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Aspects of the long-term fate of petroleum hydrocarbons in the marine environment Green, David Robin 1976

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ASPECTS OF THE LONG-TERM FATE OF PETROLEUM HYDROCARBONS IN THE MARINE ENVIRONMENT by DAVID ROBIN GREEN B. Eng., Royal M i l i t a r y College, 1970 A THESIS SUBMITTED IN THE REQUIREMENTS DOCTOR OF PARTIAL FULFILLMENT OF FOR THE DEGREE OF PHILOSOPHY i n the Faculty of Graduate Studies ( I n s t i t u t e of Oceanography) We accept t h i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 1976 <g) David Robin Green, 1976 In p r e s e n t i n g t h i s t h e s i s in p a r t i a l f u l f i l m e n t o f the r e q u i r e m e n t s f o r an advanced degree at the U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r e e that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r agree t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by the Head o f my Department o r by h i s r e p r e s e n t a t i v e s . It i s u n d e r s t o o d tha t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . Department o f OcEAnOc,gftPH1 The U n i v e r s i t y o f B r i t i s h C o l u m b i a 2075 Wesbrook Place Vancouver, Canada V6T 1W5 Date tf jL^, JUL ABSTRACT The longterm f a t e of petroleum i n four marine environments was I n v e s t i g a t e d : The f a t e of petroleum on the surface of the ocean was e l u c i d a t e d by undertaking a d e t a i l e d study of petroleum residues p o l l u t i n g the P a c i f i c Ocean. F i r s t , the extent of contamination of the P a c i f i c by petroleum residues was assessed by measuring the amounts of t a r i n 2092 neuston tows over a nine-year p e r i o d (1967-1975). The South P a c i f i c was found to be f r e e of t a r ; the Northeast P a c i f i c was s l i g h t l y p o l l u t e d , w i t h an average of 2 0.03 mg/m . The Northwest P a c i f i c , p a r t i c u l a r l y the Kuroshio current system, was the most sev e r e l y p o l l u t e d area: a l l 55 tows between 25° and 40°N i n the Northwest P a c i f i c were contaminated. The average c o n c e n t r a t i o n i n that area 2 was 2.1 mg/m , rep r e s e n t i n g a standing stock of about 25,000 met r i c tons of t a r . Chemical analyses of the t a r as w e l l as i t s d i s t r i b u t i o n p a t t e r n s t r o n g l y imply that i t o r i g i n a t e s p r i m a r i l y from tanker t r a f f i c , and from tanker sludge i n p a r t i c u l a r . The p o l l u t a n t s appear to be discharged by tanker on the very l a r g e Middle East to Japan tanker route, then become entrained i n the Kuroshio current and create a plume of contamination which extends downstream f o r 7000 ki l o m e t e r s across the P a c i f i c . I n i t i a l l y evaporation i s the most important weathering mechanism a c t i n g on the t a r , removing component up to the v o l a t i l i t y of pentadecane over a period of days or perhaps weeks. The r e a f t e r , m i c r o b i a l degradation i s dominant, probably a c t i n g f o r over a year on many p a r t i c l e s . Both of these processes increase the d e n s i t y of the res i d u e s , and t h i s e f f e c t , combined w i t h the overburden of f o u l i n g growth that develops, e v e n t u a l l y r e s u l t s i n the slow s i n k i n g of the t a r i n t o the depths of the ocean. The f a t e of petroleum i n the i n t e r t i d a l environment was s t u d i e d by f o l l o w i n g the n a t u r a l degradation of the o i l a f t e r a small (200 ton) o i l s p i l l of #5 fuel o i l . The most important weathering process was microbial degradation. Evaporation played only a minor role, while photo-oxidation and dissolution had no apparent effect. The microbal attack took approximately one year to complete the degradation of the n-paraffin fraction of the spilled o i l , leaving a thin asphaltic residue on the beach. The combined effect of microbial degradation and abrasive weathering removed roughly 95% of the o i l from the beach over the period of a year. The fate of o i l in the benthic environment was studied by treating 500 ml quantities of crude o i l with a commercial sinkant, then placing the o i l on soft sediments in about 6 meters of water. Again in the benthic environment, microbial action was the process responsible for the degra-dation of the o i l . Evaporation had no opportunity to act, dissolution was ineffective, and photo-oxidation did not occur because of the low energy and intensity of the light reaching the sediment. The benthic petroleum samples were slow to degrade: the o i l remained unchanged in chemical composition for at least 6 months, and after 16 months the n-paraffins were only partly degraded. Oil dissolved in the water column was investigated by adding a spike of #2 fuel o i l to an enclosed column of water 2 m in diameter by 15 m deep, and monitoring its fate by fluorescence spectroscopy. For water a meter or two in depth, exchange with the atmosphere played the dominant role in removing the hydrocarbons from the water column, but at 7 m and below, microbial degradation and sedimentation were the more important processes. The disappearance of the o i l approximately followed an ex-ponential decay curve. The half l i f e for a large dissolved o i l spike was about 3 days (less for a smaller spike) so that 95% removal occurred within 2 weeks. i i i TABLE OF CONTENTS Page A b s t r a c t i Table of Contents i i i L i s t of Tables vi L i s t of Figur e s v i i i Acknowledgements xi INTRODUCTION ..' 1 LITERATURE REVIEW CHAPTER 1: SUMMARY OF THE COMPOSITION OF PETROLEUM I n t r o d u c t i o n 3 The Hydrocarbons 6 The A s p h a l t i c F r a c t i o n and the Non-hydrocarbons .... 9 C h a r a c t e r i z a t i o n of Crude O i l s and Refined Products. 11 Refined Products ... 13 D i s t i n g u i s h i n g Petroleum Hydrocarbons from B i o g e n i c Hydrocarbons 15 Conclusion 15 CHAPTER 2: SOURCES OF OIL TO THE MARINE ENVIRONMENT 16 CHAPTER 3: WEATHERING OF PETROLEUM IN THE MARINE ENVIRONMENT I n t r o d u c t i o n 23 P h y s i c a l Weathering: Emulsif i c a t i o n 23 Sedimentation 26 Chemical Weathering: Evaporation 28 D i s s o l u t i o n 31 B i o l o g i c a l Degradation 39 Auto - O x i d a t i o n ...... 46 Summary of Weathering 49 RESEARCH RESULTS Page CHAPTER 4: THE WEATHERING OF PETROLEUM UNDER CONTROLLED CONDITIONS Introduction .. ^4 Method .... 54 Results 58 Discussion .. 60 Conclusions 63 CHAPTER 5: PETROLEUM RESIDUES ON THE SURFACE OF THE PACIFIC AND ARCTIC OCEANS Introduction 65 Di s t r i b u t i o n of petroleum residues on the surface of the P a c i f i c • 72 Time Series Observations of Tar Concentrations at Ocean Weather Station *P' 84 Tar D i s t r i b u t i o n i n Local Waters 87 Tar and P l a s t i c s i n the Beaufort Sea 89 V a r i a b i l i t y of Tar Concentrations 91 Size D i s t r i b u t i o n of Pelagic Tar P a r t i c l e s 96 Chemical Analyses of Tar 98 Results of Chemical Analyses 100 Discussion of Chemical Analyses 139 Source of Pelagic Tar 148 Chemical Weathering of Pelagic Tar 154 Physical Weathering and Fate of Tar ..................... 160 Ecological Effects of Pelagic Tar-.... 163 Conclusions 165 CHAPTER 6: OIL IN THE INTERTIDAL ENVIRONMENT Introduction 168 The A l e r t Bay O i l S p i l l 168 Description of the Study Area 169 Observations ...... 170 Chemical Analysis 173 Results of Chemical Analyses 177 Discussion of I n t e r t i d a l Weathering 178 Conclusions 179 CHAPTER 7: OIL IN THE BENTHIC ENVIRONMENT Page Introduction .181 Method 1 8 1 Observat ions' . . . 182 Results of Chemical Analyses . . . .183 Preservation of Heavily-Oiled Samples 187 Discussion 1^ 9 Conclusions .191 CHAPTER 8: OIL IN THE WATER COLUMN Introduction 193 Experimental Method 198 Discussion of Analyt ical Methods 201 Results 211 Discussion of Results ' 216 Conclusions 219 SUMMARY OF FINDINGS 220 CONCLUSIONS 227 BIBLIOGRAPHY 229 A P P E N D I C E S A) Some Conversion Factors and Quantities Useful in O i l Pol lut ion Research 251 B) A Literature Review of the Biological Effects of Petroleum . . . 253 C) Exchange Rates of Hydrocarbons Between Ocean and Atmosphere . . 277 D) A Personal Perspective on the O i l Pol lut ion Problem 282 E) Symposia and Books Dealing with O i l Pol lut ion 284 v i LIST OF TABLES Table Page 1. Average Composition of Crude Oils by Class of Compounds 5 2. Predominant Constituents of Petroleum 5 3. Some Characteristics of Crude O i l s ... 12 4. B o i l i n g Ranges of Petroleum Products 13 5. Average Composition of Refined Products 14 6. Budget of Petroleum Hydrocarbons Introduced into the Oceans . 17 7. Comparison of Estimates of Petroleum Hydrocarbons entering the Oceans, c i r c a 1969-1971 18 8. Melting Points, B o i l i n g Points, Vapour Pressures, arid S o l u b i l i t i e s of Selected Hydrocarbons 33 9. Effect of Photo-oxidation on Isoprenoid/Alkane Ratios i n Crude O i l 52 10. Characteristics of A r t i f i c a l l y Weathered O i l s 59 11. Tar i n the Marine Environment: A Li t e r a t u r e Summary 67 12. Chemical Analyses of Petroleum Residues: A Li t e r a t u r e Summary 70 13. Tar Concentrations Reported i n the Lite r a t u r e 71 14. Summary of the Results of Neuston Net Tows along 35°N in the P a c i f i c Ocean 73 15. Summary of Cruise Information and Average Tar Concentrations by Area i n the P a c i f i c 79 16. Summary of Weathership Time Series of Neuston Tows 85 17. V a r i a b i l i t y of Tar Concentrations i n Replicate Tows ......... 92 18. Instrumental Parameters for Gas Chromatographic Analysis .... 99 19. Summary of Chrcmatograms of Pelagic Tar 131 20. Iron and Nickel Content of Pelagic Tar Samples 136 21. Average Composition of Subclasses of Pelagic Tar 143 22. Summary of Iron Concentrations i n Pelagic Tar 147 23. Summary of Observations of the O i l S p i l l at Reserved Bay .... 171 Table Page 24. Specifications of Fuel O i l S p i l t at A l e r t Bay 173 25. Characteristics of Fuel O i l Weathering i n an I n t e r t i d a l Environment 177 26. Comparison of Refrigeration and Formalin as Methods of Preserv-ing Heavily-Oiled Samples . 187 27. Characteristics of Crude O i l Weathering i n a Benthic Environment 190 28. Reported Concentrations of Nonvolatile Hydrocarbons i n Oceanic Waters 195 29. Instrumental Parameters for Hydrocarbon Analyses of Water Samples 200 30. Results of Fluorescent Determinations of Hydrocarbons i n the CEPEX Enclosures 214 31. Percentage of Toxic Compounds i n Crude O i l 255 32. Comparison of Circumstance and Documented Damage of O i l S p i l l s 265 33. Toxic Concentrations of Crude and Refined O i l s 267 34. Theoretical Half Lives of Dissolved Hydrocarbons Exchanging with the Atmosphere 280 35. P a r t i t i o n i n e of Hydrocarbons Between Eaual Volumes of Gas and Liquid Phases 2 "1 v i i i LIST OF FIGURES Figure Page 1. D i s t r i b u t i o n of n-Paraffins i n Crude O i l 7 2. Hydrocarbon Types by Carbon Number i n a Crude O i l 8 3. Some Basic H e t e r o c y c l i c Structures i n Petroleum 10 4. O i l Seepage P o t e n t i a l of the P a c i f i c Ocean Basin 20 5. The Growth of Crude O i l Transport by Sea 21 6. Simulated Weathering of Crude O i l 29 7. Evaporative Weight Loss of Natural Seep O i l as a Function of Time f o r Open Sea Tests 29 8. Gas Chromatograms of Crude O i l Degraded by Incubation with a Mixed Population of Microorganisms 42 9. Processes Leading to the Degradation of Crude O i l at Sea 50 10. Chromatograms of A r t i f i c i a l l y Weathered Crude O i l 55 11. Chromatograms of an A r t i f i c i a l l y Weathered Heavy Fuel O i l .... 56 12. Chromatograms of A r t i f i c i a l l y Weathered D i e s e l O i l ........... 57 13. Transpac-72 Cruise Track and the Surface C i r c u l a t i o n Pattern i n the North P a c i f i c 72 14. D i s t r i b u t i o n of Tar and P l a s t i c s along 35°N i n the P a c i f i c Ocean 73 15. Temperature D i s t r i b u t i o n i n the Surface Layer along 35°N ..... 75 16. D i s t r i b u t i o n of Tar along 28°N i n the P a c i f i c Ocean 76 17. D i s t r i b u t i o n of Tar i n the P a c i f i c Ocean 78 18. Q u a l i t a t i v e Information oh Tar D i s t r i b u t i o n s i n the P a c i f i c and Indian Oceans 83 19. Location of Ocean Weather Sta t i o n P and Oceanographic Stations on Line P . .. 86 20. Locations of Neuston Tows and Beach Surveys i n L o c a l B r i t i s h Columbia Waters 88 21. Location of Neuston Tows and Beach Surveys i n the Beaufort Sea 90 i x Figure Page 22. Histograms of tar concentrations from the Western P a c i f i c along 28°N 93 2 3 . Chromatograms of Pe l a g i c Tar . . . . 101 24 . R e p r o d u c i b i l i t y of Chromatograms 140 2 5 . Pristane and Phytane i n Pe l a g i c Tar 144 2 6 . Carbon Number of F i r s t , Maximum and Last. P a r a f f i n Peaks from 82 Chromatograms of Pe l a g i c Tar 146 2 7 . Tanker Routes i n the P a c i f i c Ocean i n 1972 149 28 . Surface C i r c u l a t i o n i n the North P a c i f i c . 149 2 9 . Comparison of Chromatograms of Crude O i l , Weathered Crude, Natural Seep O i l , and Pelagic Tar 151 30. E f f e c t of Evaporation on a Crude O i l ; . . . . . 154 31. Biodegradation Index (C -18/C -19 r a t i o ) as a Function of Longitude "• 158 32. Chromatograms of a High Density Tar Lump and an Abyssal Tar Sample 161 33. Map Showing the Locale of the A l e r t Bay O i l S p i l l 170 34. Chromatograms of Fuel O i l Weathering i n an I n t e r t i d a l Environment 174 35 . Isoprenoid/Paraffin Ratios i n Fuel O i l Weathering i n an I n t e r t i d a l Environment 176 36. Chromatograms of Crude O i l Weathering i n a Benthic Environment 184 37. Isoprenoid/Paraffin Ratios i n Crude O i l Weathering i n a Benthic Environment 186 38. Chromatograms Showing the E f f e c t of Storage on Preserved O i l Samples • • • • 188 39. L i n e a r i t y of Fluorescence Response f o r Determination of Hydrocarbon Concentrations 204 40. E f f e c t of D i s t i l l a t i o n on Solvent Blanks 207 41. D i s t i l l e d Water Blank 208 42 . E f f e c t of a Preparative S i l i c a Gel Column on Gas Chromatographic Analysis 208 43. R e p l i c a t i o n of Gas Chromatographic Analyses of Water Samples • • • 209 X Figure Page 44. A Contaminated Sample from the Control Enclosure 210 45. Gas Chromatograms of #2 Fuel O i l and i t s Saturated Seawater Extract 212 46. Fluorescence Results for CEPEX Hydrocarbon Experiment 213 ACKNOWLEDGEMENTS I was l u c k y e n o u g h , d u r i n g my a d j u s t m e n t t o g r a d u a t e s c h o o l a f t e r a n u n d e r g r a d u a t e c a r e e r i n a c o m p l e t e l y d i f f e r e n t e n v i r o n m e n t , t o l a n d i n v e r y c a p a b l e h a n d s . D r . T im P a r s o n s o f U . B . C . gave me a r o a d t o f o l l o w and encou ragemen t t o f o l l o w i t ; D r . C . S . Wong, o f t h e D e p a r t m e n t o f E n v i r o n m e n t , c o n t r i b u t e d more t r u s t and o p p o r t u n i t i e s t h a n any g r a d u a t e s t u d e n t d e s e r v e s ; and D r . W a l t e r C r e t n e y , a l s o o f t he D e p a r t m e n t o f E n v i r o n m e n t , p a t i e n t l y t a u g h t and a d v i s e d me. B i l l H e a t h , a g r a d u a t e s t u d e n t a t t h e I n s t i t u t e o f O c e a n o g r a p h y , d i d a l l t h e k e y i n g and i d e n t i f i c a t i o n o f o r g a n i s m s a s s o c i a t e d w i t h t a r l u m p s . Many t a r s a m p l e s we re o b t a i n e d f r o m t h e S c r i p p s I n s t i t u t i o n o f O c e a n o g r a p h y t h r o u g h t h e k i n d c o - o p e r a t i o n o f D r . W a r r e n W o o s t e r , D r . McGowan, and D r . L a n n a C h e n g . The n e u s t o n tows i n t h e B e a u f o r t S e a w e r e p e r f o r m e d u n d e r c o n -t r a c t by Seakem O c e a n o g r a p h y L t d . o f V i c t o r i a and t h e b e a c h s u r v e y by D a v i d MacDona ld o f C a s e E x i s t o l o g i c a l L a b o r a t o r y L t d . C a r o l e Bawden , a r e s e a r c h a s s i s t a n t a t U . B . C , made t h e b i o l o g i c a l o b s e r v a t i o n s a t t h e A l e r t Bay o i l s p i l l . The method o f s i n k i n g t h e o i l u s e d i n t h e b e n t h i c e x p e r i m e n t was d e v e l o p e d by G a r y S i l v e r , a g r a d u a t e s t u d e n t a t t h e U n i v e r s i t y o f V i c t o r i a . The a s s i s t a n c e o f v a r i o u s s t a f f members a t t h e CEPEX s i t e , p a r t i c u l a r l y F r a n k W h i t n e y , i s g r a t e f u l l y a c k n o w l e d g e d . D r . R i c h a r d L e e p e r f o r m e d t h e i n f r a r e d measu remen ts and d e t e r m i n e d t h e m i c r o b i a l h y d r o c a r b o n d e g r a d a t i o n r a t e s w h i c h a r e q u o t e d i n c o n n e c t i o n w i t h t h e CEPEX e x p e r i m e n t . P h i l Montgomery and R o b e r t P u r d y w o r k e d a s s t u d e n t a s s i s t a n t s f o r p e r i o d s d u r i n g t h e summers. F i n a n c i a l s u p p o r t came f r o m a N a t i o n a l R e s e a r c h C o u n c i l C e n t e n n i a l S c i e n c e S c h o l a r s h i p ( 1 9 7 1 - 7 4 ) and a K i l l a m P r e - d o c t o r a l F e l l o w s h i p ( 1 9 7 5 ) . The Ocean C h e m i s t r y d i v i s i o n o f Ocean and A q u a t i c S c i e n c e s , D e p a r t m e n t o f E n v i r o n m e n t , p r o v i d e d r e s e a r c h f a c i l i t i e s , t r a v e l f u n d s , and s h i p t i m e . To those who wove the s o c i a l f a b r i c of my graduate student years: the g i r l who loved people; the f r i e n d from pathology;, the lady from A f r i c a ; the woman of the woods; and the r i v e r t r a v e l l e r s . INTRODUCTION In contrast to most previous work, which was done under a r t i f i c i a l laboratory conditions, t h i s t h e s i s examines the f a t e of petroleum under n a t u r a l conditions i n the marine environment - as residues on the surface of the open ocean; as an o i l s p i l l i n an i n t e r t i d a l area; as sunken o i l on the sediment i n about 6 meters of water; and as dissol v e d o i l mixed i n t o the water column. Since much of the background information required i n a d i s c u s s i o n of o i l p o l l u t i o n problems i s not common knowledge or r e a d i l y a c c e s s i b l e i n the l i t e r a t u r e , a considerable e f f o r t has been made to review the relevant aspects of o i l p o l l u t i o n research. The f i r s t two chapters summarize sub-j e c t s which provide background information f o r the re s t of the t h e s i s : the composition of petroleum, and the sources of o i l to the marine environment. Chapter 3 then thoroughly reviews the l i t e r a t u r e dealing with the weathering processes which a f f e c t o i l . ' A small preliminary experiment i s described i n Chapter 4 i n which various o i l s were weathered under c o n t r o l l e d conditions so that only evap-oration and photo-oxidation could occur. The e f f e c t of these processes on the composition of the o i l s i s assessed. Chapter 5 reports the r e s u l t s of the f i r s t major research t o p i c : p e r s i s t e n t petroleum residues i n the P a c i f i c Ocean. The d i s t r i b u t i o n of pelagic t a r on the surface of the North and South P a c i f i c and the Beaufort Sea i s reported and a map of tar contamination of the P a c i f i c i s presented. The source of the t a r i s i d e n t i f i e d from the d i s t r i b u t i o n pattern and by chemical analyses.The eventual f a t e and the prime mechanism of degradation of the petroleum residues are also i n f e r r e d from the analyses. The standing stock of tar i n the north-western P a c i f i c i s c a l c u l a t e d , and the e c o l o g i c a l e f f e c t s of the tar are discussed. In Chapter 6 the long-term fate of o i l i n the i n t e r t i d a l environment is researched. An o i l s p i l l was sampled over a year-long period, and gas chromatographic analyses were used to assess both the rate of degradation of the oi l and the prime mechanism of degradation. In Chapter 7, the same analytical technique and reasoning were used to investigate the degrada-tion of o i l sunk by treatment with a sinking agent and left to weather for an extended period (18 months) in about 6 meters of water. Finally, Chapter 8 deals with the degradation of o i l dissolved in the water column. The experiments were carried out using a trapped water column as a part of the Controlled Ecosystem Pollution Experiment. This was the most difficult of the four projects in terms of analytical method, because of the low levels at which hydrocarbons dissolve in water. The gas chromatographic investigations were not a success, for reasons that are discussed, sp the disappearance of the o i l was monitored using fluorescence. The results give an indication of the rate and the mechanisms of removal of the o i l from the water column. Five appendices are included giving some useful technical information, a review of the biological effects of petroleum, a theoretical discussion of hydrocarbon exchange rates between ocean and atmosphere, an opinion, and a li s t of symposia and books dealing with o i l pollution. The thesis concludes with an extensive bibliography of the literature relevant to o i l pollution research. CHAPTER 1 3 SUMMARY OF THE COMPOSITION OF PETROLEUM I n t r o d u c t i o n The term 'petroleum', here as elsewhere, i s used interchangeably w i t h 'mineral o i l 1 and 'crude o i l 1 . I t i s d e r i v e d from the L a t i n p e t r a , f o r rock, and oleum, f o r o i l . The f a t e of petroleum i n the marine environment depends on i t s composition, so a d i s c u s s i o n of the main chemical components i s r e q u i r e d . The complexity and v a r i a t i o n of composition i s immense, but some genera-l i z a t i o n s can be made. The elements found i n petroleum are carbon (83-87%), hydrogen (11-15%), oxygen (0-5%), s u l f u r ( 0-6%), n i t r o g e n (0-0.5%), and t r a c e amounts of metals, c h i e f l y vanadium, n i c k e l , i r o n , sodium, c a l c i u m , and copper* t o t a l l i n g 0.1 to 100 ppm (percentages are from F r a n k e n f e l d , 1973b). The main c l a s s of compounds present i s hydrocarbons, which comprise 75-98% by weight of crude o i l . The remainder i s made up of n i t r o g e n - , s u l f u r - , and oxygen- c o n t a i n i n g compounds (NSO compounds) which are g e n e r a l l y of h i g h molecular weight and complex s t r u c t u r e . No s i n g l e crude has ever been completely analysed i n t o i t s i n d i v i d u a l components. The most complete a n a l y s i s has been performed on Ponca C i t y crude o i l , under the auspices of the American Petroleum I n s t i t u t e research p r o j e c t 6, which, by 1959, had i d e n t i f i e d 169 hydrocarbons comprising 46% of the crude ( R o s s i n i and Mair, 1951, 1959). By 1967, s e v e r a l hundred hydrocarbons and two hundred s u l f u r compounds had been i d e n t i f i e d i n crude o i l s (Mair, 1965; Mair and Ronen, 1967; Hunt and O'Neal, 1967; Bestougeff, 1967). Recent ana-l y t i c a l developments, such as i n t e r f a c e d gas chromotography - mass s p e c t r o -metry and nuclear magnetic resonance spectroscopy, have g r e a t l y enlarged the number of compounds which can be i d e n t i f i e d (Coleman et a l , 1973), but complete i d e n t i f i c a t i o n of a crude o i l i s s t i l l not p o s s i b l e , nor, perhaps, worthwhile. 4 This i s not meant to imply, however, that the composition of petro-leum i s i n f i n i t e l y complex. I t appears that d e f i n i t e , regular processes have produced petroleum, with the re s u l t that the t o t a l number of isomers, although high, i s only a negl i g i b l e percentage of the t o t a l number of theo r e t i c a l structures (Bestougeff, 1967). Examples of the underlying order i n petroleum are: (a) the presence of sets of homologous series of compounds i n a l l petroleums (Bestougeff, 1951); and (b) the consistent finding that older Palaeozoic petroleums are more a l i -phatic, and newer Tertiary petroleums more c y c l i c i n composition suggesting an orderly process of ageing (Bestougeff, 1967). The sequence of events which has lead to t h i s complex but neverthe-less orderly composition of petroleum i s succinctly summarized by Ehrhardt and Blumer (1972): The geochemical processes responsible for the formation of crude o i l lead to the production of an immense number of i n d i v i d u a l hydrocarbons, including many isomers and members of dif f e r e n t homologous series. Each petroleum i s an ind i v i d u a l product whose composition r e f l e c t s the chemistry of i t s source materials. In addition, i t carries the i n d e l i b l e imprint of the geochemical subsurface processes that have lead to i t s formation. The time-temperature history and the inorganic components of the source beds af-fect the crude o i l composition i n a way that i s understood i n general terms but not i n molecular d e t a i l . Further a l t e r a t i o n of a crude o i l may take place i n a reservoir, either through thermal cracking after deep submergence or through b a c t e r i a l a l t e r a t i o n i n shallow traps. ....Many structures formed by l i v i n g organisms (four and f i v e r i n g naphthenes, porphyrins, etc.) survive i n crude o i l . Their composition i s strongly affected by the inten-s i t y of the chemical processes responsible for the formation of petroleum. Thus, the very small number of tetrapyrrole pigments may be converted by geochemical processes into thousands of d i f f e r e n t f o s s i l porphyrins whose structures are a unique r e f l e c t i o n of the subsurface conditions. Table 1 gives a very approximate summary of crude o i l composition by molecular size and molecular class. Table 2 l i s t s some of the predominant compounds i n crude o i l , and thei r percentage occurrence. Detailed compara-tive analyses of crude o i l are available (Martin et a l , 1963). TABLE 1: Average Composition of Crude O i l By Class of Compounds Bv Molecular Size: By Molecular Class: gasoline .(C5'-C10> 30% kerosine (C.--C, „) 10% 1U JLZ l i g h t d i s t i l l a t e ( C 1 2 - C 2 Q ) 15% heavy d i s t i l l a t e ( C2o~ C4(p 2 5 % r e s i d u a l ( CUQ) 20% p a r a f f i n s 15-35% o l e f i n s 0% naphthenes 30-50% aromatics 5-20% polar NSO cmpds 2-15% (From Petroleum i n the Marine En- vironment, 1975, p.43) (From Z o b e l l , 1973, p.5) TABLE 2: Predominant  Constituents of Petroleum No. Series and hydrocarbon Carbon atom number Percent of crude oil (From Bestougeff, 1967, p.80) Normal paraffins 1 Pentane 2 Hexane 3 Heptane 4 Octanc-Decane 5 Undccane-Pentadecane 6 Hexadecane and higher Isoparaffins 1 2-Mcthylpentane 2 3-Methylpentane 3 2-Methylhexane 4 3-Methylhexane 5 2-Mcthylheptane 6 3-Methylheptane 7 2-Methyloctane 8 3-Methyloctane 9 2-Methylnonane 10 3-Methylnonane 11 4-Methylnonane 12 Pristane (isoprenoid) Cycloparaffins 1 Methylcyclopentane 2 Cyclohexane 3 Methylcyclohexane 4 1, trans-2-dimethylcycIopentane 5 1, cis-3-dimethylcyclopcntane 6 1, cis-3-dimethy!cyclohcxane 7 1, cis-2-dimethylcyclohcxane 8 1,1, 3-trimethylcyclohexane Aromatics 1 Benzene 2 Toluene 3 Ethylbcnzene 4 m-Xylene 5 l-Mcthyt-3-ethylbcnzene 6 1, 2, 4-Trimethylbcnzene 7 1, 2, 3-Trimcthylbcnzcnc 8 .1.2, 3, 4-Tctramcthylbcnzcne 9 2-Mcthylnaphtalcne 10 2,6-Dimcthylnaphtalene 11 Trimethylnaphtalene Cs C« Ci Ca-Cio C l l - C l 5 d a and higher Ce C6 C 7 Ci c 8 Cs c C 9 Cio ClO Cio Gl9 d Ce C 7 C 7 Ci C 8 Cs C 9 C 6 C 7 Cs Cs Co c 9 C 9 Cio Cn Cn Cia 0.2 0.04 0.03 0 0 0 0.2 0.06 0.03 0.02 0.03 0.02 0.02 0.01 0.11 0.08: 0.25 0.05 0.04 0.01 0.03 0.01 0.02 3.2 2.6 2.5 1.8-2.0 0.8-1.5 <1.0 1.16 0.9 1.1 0.9 1.0 0.4 0.4 0.2 0.3 0.1 0.1 1.12 2.35 1.4 2.8 1.2 1.0 0.9 0.6 0.7 1.0 1.8 1.6 1.0 0.3 0.6 0.4 0.3 0.3 0.4 0.3 6 The Hydrocarbons The hydrocarbons i n crude o i l are grouped i n t o f o u r main c l a s s e s : p a r a f f i n s , o l e f i n s , naphthenes and aromatics. The p a r a f f i n s i n c l u d e a l l non-c y c l i c alkanes, ranging from f i v e up to f i f t y carbon atoms per molecule. They are of lower d e n s i t y and s o l u b i l i t y than the other c l a s s e s . Of p a r t i c u l a r prominence are the homologous s e r i e s of normal alkanes and of i s o p r e n o i d com-pounds. The d i s t r i b u t i o n of normal p a r a f f i n s i n two crude o i l s i s i l l u s t r a t e d i n F i g ure 1. C l e a r l y , the p a r a f f i n i c content v a r i e s w i d e l y (note the d i f f e r -i n g y - a x i s expansions). The i s o p r e n o i d compounds deserve s p e c i a l mention. They were f i r s t i d e n t i f i e d i n petroleum i n the e a r l y 1960's through the a p p l i c a t i o n of the new technique of gas chromatography ( B e n d o r a i t i s et a l , 1962). The d i s c o v e r y was e x c i t i n g because i t provided long-sought evidence f o r the b i o l o g i c o r i g i n of petroleum: the i s o p r e n o i d s are d i r e c t l y r e l a t e d to the b i o c h e m i c a l l y -synthesized terpenes. The most abundant of the i s o p r e n o i d s i n petroleum are p r i s t a n e (2, 6, 10, 14 - tetramethylpentadecane) and phytane (2, 6, 10, 14 -tetramethylhexadecane). Both are thought to d e r i v e from the p h y t o l group i n c h l o r o p h y l l ( B e n d o r a i t i s et a l , 1963). T h e i r c o n c e n t r a t i o n s vary from 0.05% to 0.5% of crude o i l , and g e n e r a l l y are w i t h i n a f a c t o r of 2 of the concen-t r a t i o n s of alkanes of s i m i l a r b o i l i n g p o i n t ( M a r t i n et a l , 1963). O l e f i n s , or alkenes, are found only i n t r a c e amounts i n crude o i l . A measure of the o l e f i n content i s the sometimes quoted 'bromine number' of o i l s . O l e f i n s are, however, formed i n the c r a c k i n g process at r e f i n e r i e s , and so occur to a l i m i t e d extent i n r e f i n e d products, p a r t i c u l a r l y g a s o l i n e . The naphthenes i n c l u d e a l l compounds w i t h s a t u r a t e d r i n g s t r u c t u r e s , that i s , a l l the c y c l o a l k a n e s . This broad range of compounds extends up to as many as s i x r i n g s , and i n c l u d e s enormous v a r i e t i e s of a l k y l s i d e c hains. FIGURE 1: Distribution of n-Paraffins in Crude Oil In Kawkawlin crude o i l : 15 20 CARBON NUMBER In Uinta Basin crude o i l : 15 20 CARBON NUMBER (From Martin et al, 1963, pp. 255-6) 8 Xhe aromatics i n c l u d e a l l compounds which c o n t a i n an aromatic r i n g s t r u c t u r e . Again, there i s a very r i c h v a r i e t y of compounds w i t h up to s i x aromatic r i n g s arranged i n v a r i o u s f a s h i o n s , s u b s t i t u t e d w i t h a wide a r r a y of a l k y l s i d e chains. The aromatics are the most s o l u b l e , the most dense, and the most t o x i c of the hydrocarbon c l a s s e s . Figure 2 shows the r e l a t i o n s h i p between the c l a s s e s of hydrocarbons i n crude o i l . T y p i c a l l y crudes are p a r a f f i n i c below about C-20, and become aromatic at higher carbon numbers (Martin et a l , 1963). FIGURE 2: Hydrocarbon Types by Carbon Number i n a Crude O i l T — r — i 1 1 r 0 4 S 12 16 20 24 28 CARBON NUMBER (From M a r t i n et a l , 1963, p.251. The o i l i s Kawkawlin crude.) The four groups of hydrocarbons and t h e i r permutations (eg naphthe-noaromatic) i n c l u d e a l l the p o s s i b l e hydrocarbons. However, p r a c t i c a l usage has lumped the high-molecular weight hydrocarbons of u n c e r t a i n s t r u c t u r e i n t o a p o r t i o n of crude o i l termed the a s p h a l t i c f r a c t i o n . •9 ••: The A s p h a l t i c F r a c t i o n and the Non-hydrocarbons The a s p h a l t i c p o r t i o n of crude o i l i n c l u d e s h i g h molecular weight compounds (above about 500 MW) both hydrocarbon and non-hydrocarbon. The d e t a i l e d s t r u c t u r e of the compounds i s s t i l l not known, so the d e f i n i t i o n i s based on p h y s i c a l p r o p e r t i e s r a t h e r than chemical s t r u c t u r e . The d e f i n i t i o n v a r i e s (Erdman, 1965; Witherspoon and W i n n i f o r d , 1967), a commonly-used one being the residue remaining a f t e r n o n - d e s t r u c t i v e d i s t i l l a t i o n up to 371°C (700°F). Wi t h i n the a s p h a l t i c f r a c t i o n , s e v e r a l terms are used to d e s c r i b e d i f -f e r e n t f r a c t i o n s . R e s i n s are the components s o l u b l e i n n-pentane but i n s o l u -b l e i n benzene. Asphaltenes are i n s o l u b l e i n n-pentane but s o l u b l e i n benzene. Carbenes, or coke, are the h e a v i e s t components, c o n s i s t i n g of h i g h l y condensed aromatic r i n g s t i e d together by short chains.' Carbenes are i n s o l u -b l e i n n-pentane, and only p o o r l y s o l u b l e i n benzene (Erdman, 1965). The a s p h a l t i c f r a c t i o n of petroleum contains most of the non-hydro-carbons, i . e . the s u l f u r - , , n i t r o g e n - , and oxygen- c o n t a i n i n g compounds. S u l -f u r may e x i s t as f r e e s u l f u r (from 2-30% of t o t a l S ) , but most i s i n o r g a n i c s u l f u r compounds such as s u l f i d e s and thiophenes. D i s u l f i d e s and mercaptans occur i n much lower concentrations ( C o n s t a n t i n i d e s and A r i c h , 1967). The s u l f u r compounds are d e a l t w i t h i n d e t a i l by Thompson et a l (1965). Oxygen i s present l a r g e l y as organic a c i d s . Phenols are present i n smaller amounts, u s u a l l y l e s s than 0.1%, and ketones occur only i n t r a c e s (Constantinides and A r i c h , 1967). A l l crude o i l s c o n t a i n at l e a s t traces of n i t r o g e n compounds, but never more than 1%. T h e i r d i s t r i b u t i o n i s s t r o n g l y skewed towards the h i g h e s t molecular weight f r a c t i o n of crude. Only b a s i c n i t r o g e n compounds have been completely i d e n t i f i e d s i n c e they are more e a s i l y i s o l a t e d . About 25% of 10 FIGURE 3: Some B a s i c H e t e r o c y c l i c S t r u c t u r e s i n Petroleum C-COOH C-C-COOH OH nopthenic acids phenol C-C-C-C-SH O O alkylthiol cycloalkylthiol thiophene 0 pyridine quinoline • H pyrrole metolloporphyrln indole (From A t l a s , 1972, p.22.). n i t r o g e n compounds are b a s i c , and are made up of a l k y l a t e d p y r i d i n e s , p y r r o l e s , q u i n o l i n e s , i n d o l e s and oth e r s . Another 20% of the n i t r o g e n appears as metal-porphyrin complexes (Constantinides and A r i c h , 1967). Both the oxygen and n i t r o g e n compounds are comprehensively reviewed by Lochte and Lettman (1955), a l l non-hydrocarbons by Consta n t i n i d e s and A r i c h (1967), and a s p h a l t i c s i n general by Dean and Whitehead (1963), Erdman (1965), Sergienko (1965), and Witherspoon and Winniford (1967). 11 Characterization of Crude O i l s and Refined Products Since crude o i l s and t h e i r products vary a great deal i n t h e i r com-position," various parameters are used to indicate the general nature of t h e i r density. Specific g r a v i t i e s of crude vary over the range 0.75 to 1.0. In the petroleum industry the density of o i l s i s referred to i n degrees of API gravity. The relationship to the s p e c i f i c gravity i s given by: API = 141.5 - 131.5 (at 60°F) ' Sp. Gr. API g r a v i t i e s vary from about 45 ( l i g h t , s p e c i f i c gravity 0.8) to 10 (heavy, s p e c i f i c gravity 1.0). Crudes are also c l a s s i f i e d by th e i r s u l f u r content. Low sul f u r petroleums are referred to as sweet, and high su l f u r as sour, for obvious reasons. The l i n e of demarcation i s about 1% sul f u r (Schmidt, 1969). Visc o s i t y i s a t h i r d parameter widely used for characterizing o i l s . The metric measure of v i s c o s i t y i s the poise: the r a t i o of the shearing stress 2 -1 i n dynes/cm to the rate of shear i n sec. , which i s a constant according to Newton's law. I t i s a measure of the l i q u i d ' s resistance to flow. Here, as i n other matters, the petroleum industry has gone i t s own way, and uses units based on convenience of measurement. Vi s c o s i t y i s given i n seconds required for 60 cc of o i l to flow through a standardized tube (Saybolt Universal v i s -cometer) at a d e f i n i t e temperature. More recently the kinematic v i s c o s i t y has been used. Happily, i t i s reported i n cgs unit s , the centistoke (stoke = poise -t density of f l u i d ) . A fourth parameter used i s the pour point. I t i s defined as the temperature 5°F above the point at which the o i l becomes s o l i d (approximately the temperature at which the kinematic v i s c o s i t y reaches 300,000 centistokes). The o i l congeals primarily because of the formation of wax crystals (Schmidt, 1969). 12 Crude o i l s are also c l a s s i f i e d by the chemical composition. There are nine c l a s s i f i c a t i o n s : p a r a f f i n i c , naphthenic, aromatic, asphaltic, and combinations of these. The percent composition f o r each i s spe c i f i e d (see Sachanen, 1945). Table 3 l i s t s a variety of crude o i l s and th e i r c h a r a c t e r i s t i c s . Other l i s t s are available (Dean, 1968; Fallah et a l , 1972). TABLE 3: Some Characteristics of Crude Oils Residue Residue Crude oil Specific Sulphur Kinematic Pour Wax Asphalt- Vanadium Acidity > 7 0 0 0 F > 7 o o ° F gravity content, viscosity, point, content, enes content, mg KOH/ % wt pour % wt 100 0 FcS °F % wt % wt ppm g on crude point °F Libyan 0-829 0 - 2 I 4-13 45 1 1 4 0 1 3 5 ' o-19 37-S 100 Zelten Nigerian 0-867 o-19 5 - i 6 5 8-5 9 5 5 . 0-14 35-8 110 Light Iran Light 0-854 1-33 5 6 - 5 7 - 0 0 - 7 36 0 - 0 7 4 2 - 7 8 0 . (Agha Jari) Iran Heavy 0-869 i - 5 8 8-83 10 6-7 1 9 107 o-13 4 7 - 8 80 (Gach Saran) Iraq 0-845 i - 8 8 4-75 - 3 0 6-s .''3 25 o-17 3 9 - 8 80 Kirkuk Kuwait 0 8 6 9 2-5 9 6 - 2 5 5 '5 i - 4 27 0 1 5 5i-.3 70 • Venezuela Tia Juana 0-896 i - 5 4 33-75 - 3 0 4 - 8 3-05 170 0-41 57-7 5 ° Medium (From Berridge et a l , 1968, p.49) Refined Products Several of the refined petroleum products are important from the point of view of marine pollution. The refined products most likely to reach the marine environment in large quantities are those used as fuels: gasoline, kerosine (#1 fuel o i l ) , diesel fuel (#2 fuel oil) and heavy fuel oils. The characteristic boiling ranges of each are given in Table 4. TABLE 4: Boiling Ranges of Petroleum Products Fraction Boiling Range (°C) Gasoline 30 - 200 Kerosine (#1) 150 - 250 Diesel fuel (#2) 160-400 Fuel o i l (#5 & 6) 320 - 540 The grades of fuel o i l are frequently bandied about in the petroleum pollution literature, and perhaps deserve some clarification. There are in fact five grades of fuel o i l , designated as numbers 1, 2, 4, 5 and 6 (#3 was combined with #2 by decree in 1948). Fuel oils #1 and #2 are referred to as distillate oils since they can be distilled at moderate temperatures (150° -350°C) at atmospheric pressure. Fuel o i l #1 (kerosine) is characterized by being sufficiently volatile to burn in vapourizing burners. #2 fuel o i l is familiar as diesel o i l , and less familiar as gas o i l . #4 fuel o i l is used only to a limited extent, mainly for small boilers in schools and apartments. It is not significant as a marine pollutant. Fuel oils //5 and #6 are referred to as residual oils, since they are obtained mainly from the residue left after distillation. They are characteristically heavy, black, and of complex compo-sition. Fuel o i l #6 is differentiated from #5 by the fact that i t requires 14 preheating for handling and burning (#5 may require preheating in cold c l i -mates) . XThese fuels are used on freighters where they are referred to as grades of bunker o i l . For example, bunker C is equivalent to fuel o i l #6. The composition of the various refined products most likely to reach the marine environment, and their physical properties, are summarized in Table 5. An important variable affecting the composition is the method of refinery production. Straight-run distillates are obtained directly by distillation from crude o i l , whereas cracked products are obtained by decomposing the heavy end of crude. Catalytically-cracked products have a higher aromatic and lower paraffinic content than straight-run distillates, due to dehydrogenation of the paraffinic and naphthenic compounds during cracking. The olefinic content is slightly increased. Thermally-cracked oils have s t i l l higher olefinic and aromatic content, but since they are easily oxidized to form sludge, they are not usually marketed without further processing. Further information on the fuel oils is available in Schmidt (1969) , from which most of this subsection was drawn. TABLE 5: Average Composition of Refined Products • Bunker C (#6 Fuel Oil) Diesel (#2 Fuel Oil' Kerosine Virgin Gasoline Blended Gasoline Paraffins 15% 30% 35% 50% Olefins 0 trace trace 0 0-30% Naphthenes 40% 45% 50% 40% Aromatics 25% 25% 15% 10% 20 - 30% Polar NSO Cmpds 15% 0 0 0 Specific Gravity 1.00 .825-.850 .800 .700 Viscosity (cps, 38°C) 1,000 40 1-2 <1 Pour Point (°C) 21° -20.5° Carbon Numbers C™+ C -C r c c„ c • 30 12 25 10 12 5-10 (From Petroleum in the Marine Environment, 1975, p.43) 15 D i s t i n g u i s h i n g Petroleum Hydrocarbons from B i o g e n i c Hydrocarbons Petroleum p o l l u t i o n m o n i t o r i n g , e s p e c i a l l y i n the a n a l y s i s of t i s -sue, r e q u i r e s the a n a l y s t to be aware of the c h a r a c t e r i s t i c d i f f e r e n c e s be-tween crude o i l hydrocarbons and the n a t u r a l l y - o c c u r r i n g hydrocarbons i n organisms. In g e n e r a l , petroleum contains a much more complex mixture of hydro-carbons, w i t h g r e a t e r ranges of molecular weight, than the n a t u r a l hydrocarbons found i n organisms. S p e c i f i c a l l y , the a l k y l - s u b s t i t u t e d r i n g compounds, common i n petroleum, have not been reporte d i n organisms. Examples are the s e r i e s of mono-, d i - , t r i - , and t e t r a m e t h y l benzenes, and the mono-, d i - , t r i - , and t e t r a m e t h y l naphthalenes. N e i t h e r have the naphthenoaromatic nor most of the NSO compounds pr e v a l e n t i n petroleum been found i n organisms (Petroleum i n the Marine Environment, 1975). The most o f t e n - c i t e d d i f f e r e n c e between petroleum and b i o g e n i c hydro-carbons i s , however, i n the spectrum of alkanes. Most petroleums show no pre-dominence of odd-carbon over even-carbon alkanes ( M a r t i n et a l , 1963). Organ-isms, however, o f t e n show a strong odd-carbon predominence, p a r t i c u l a r l y i n the C-15 to C-21 alkanes ( C l a r k , 1966; Blumer et a l , 1 9 7 l ) . Conclusion The foregoing d i s c u s s i o n of the composition of petroleum and i t s products provides the background i n f o r m a t i o n a g a i n s t which the m o d i f i c a t i o n and degradation of o i l s by the v a r i o u s weathering processes can be evaluated and understood. These mechanisms are discussed i n d e t a i l i n Chapter 3. How-ever, before proceeding, there i s some a d d i t i o n a l background i n f o r m a t i o n which needs to be presented. CHAPTER 2 SOURCES OF OIL TO THE MARINE ENVIRONMENT 16 The estimation of o i l reaching the oceans i s a complex and specula-t i v e matter i n which opinion plays a s i g n i f i c a n t r o l e . I t has been stated, for instance, by a B r i t i s h researcher (Victory, 1973), with reference to American figures on sources of o i l , that "...there i s one c h a r a c t e r i s t i c which can always be guaranteed: that the figures coming from the other side of the A t l a n t i c w i l l have a factor of the magnitude of 2 or 3 above those from t h i s side". Despite the opinion of Mr. Vi c t o r y , the most comprehensive and care-f u l estimates of the amounts of o i l reaching the ocean were arrived at by the U.S. National Academy of Sciences (Petroleum i n the Marine Environment, 1975). Previous estimates of petroleum inputs were reviewed, and the uncertainties and assumptions were c a r e f u l l y stated. The tables of estimates prepared by the Academy of Sciences i s presented i n Table 6. Table 7 compares the figures with estimates from two other studies. The estimates range from well-documented to undocumented. With reference to Table 6, the transportation sources are supported by years of data. However, at the other end of the spectrum, the hydrocarbon quantities contributed by the atmosphere are arrived at by cumulative black magic which involves estimating the amount of hydrocarbons l o s t to the atmosphere, the amount of reaction occurring i n the atmosphere, and the amount of p r e c i p i t a -t i o n of unreacted hydrocarbons i n t o the marine environment, none of which have much supporting data. I t i s important to r e a l i z e that the various sources introduce quite d i f f e r e n t fractions and forms of o i l i n to the oceans. The sources l i s t e d i n Table 6 as coastal r e f i n e r i e s , atmosphere, coastal wastes, and run-off pro-duce dissolved hydrocarbons and some t h i n s l i c k contamination. In contrast, natural seeps and marine o i l transport can produce thick s l i c k contamination 17 TABLE 6: Budget of petroleum Hydrocarbons Introduced Into the Oceans Source Input Rate (mta) a Best Estimate Probable Range Natural seeps 0.6 0.2 - 1.0 Offshore production 0.08 0.08 - 0.15 Transportation LOT tankers 0.31 0.15 — 0.4 Non-LOT tankers 0.77 0.65 - 1.0 Dry docking 0.25 0.2 - 0.3 Terminal operations 0.003 0.0015 - 0.005 Bilges, bunkering 0.5 0.4 - 0.7 Tanker accidents 0.2 0.12 - 0.25 Nontanker accidents 0.1 0.02 - 0.15 Coastal r e f i n e r i e s 0.2 0.2 - 0.3 Atmosphere 0.6 0.4 - 0.8 Coastal municipal wastes 0.3 Costal, Nonrefining, i n d u s t r i a l wastes 0.3 -Urban runoff 0.3 0.1 - 0.5 River runoff 1.6 -TOTAL 6.1 mta, m i l l i o n metric tons per annum (Table from Petroleum i n the Marine Environment, 1975, p.6.) TABLE 7: Comparison of Estimates of petroleum Hydrocarbons Annually Entering the Oceans, Circa 1969 - 1971 18 Authority ( M i l l i o n s of Tons per Annum) Source MIT SCEPT Report (1970) USCG Impact Statement (1973 NAS Workshop (1973) Marine transportation Offshore o i l production Coastal o i l r e f i n e r i e s I n d u s t r i a l waste Municipal waste Urban runoff River runoff 1.13 0.20 0.30 0.45 1.72 0.12 1.98 2.133 0.08 0.3 0.3 0.3 1.6 SUBTOTAL 2.08 3.82 4.913 Natural seeps Atmospheric rainout ? 0.6 0.6 TOTAL 11.08 6.113 SHC input from recreational boating assumed to be incorporated i n the r i v e r runoff value. ^Based upon assumed 10 percent return from the atmosphere. (Table from Petroleum i n the Marine Environment, 1975, p.6) and persistent o i l residues. I t i s these sources of persistant o i l which are most relevant to t h i s discussion. Marine o i l seepage has been reviewed by Wilson et a l (1974). The amount of natural seepage i s estimated by quantifying known seeps, then multiplying by the area i n which seepage i s l i k e l y to occur at that rate. Figure 4 shows the areas of low, moderate, and high estimated seepage i n the P a c i f i c . The number of marine o i l seeps actually observed i s very small, so that the amount of extrapolation involved i s very large. Blumer (1972) has calculated that i f o i l seepage i s on the same sort of magnitude as anthropogenic inputs, marine reservoirs of o i l would have long ago been ex-hausted. By t h i s l i n e of reasoning, the estimate by Wilson of 0.6 mta ( m i l l i o n metric tons per year) i s much too high, which points out the uncertainty i n the extimate, but does not otherwise c l a r i f y the s i t u a t i o n . FIGURE 4: O i l Seepage P o t e n t i a l of the P a c i f i c Ocean Basin «• iit* tjr iit* „^_____ or w (From Wilson et a l , 1974) The second major source of p e r s i s t e n t o i l s i s marine o i l trans-portation. In Table 6 t h i s has been broken down into s i x subsections. The f i r s t three of these can be lumped together as routine tanker operations. They contribute 1.33 mta to the marine environment, an amount that i s both large and well documented. The p o l l u t i o n occurs because of the clingage of o i l to walls of the tanks i n which i t i s carried. The clingage factor can vary anywhere between 0.1% of the cargo for refined products up to 1.5% for residual f u e l o i l s (Petroleum i n the Marine Environment, 1975). However, crude o i l i s the primary cargo of tankers (see Figure 5), and the clingage factor for crude varies from 0.3 to 0.4% (Kirby, 1968; Holdsworth, 1971). The clinging o i l becomes mixed with sea water when the tanker b a l l a s t s or cleans i t s tanks. I t i s then pumped overboard p r i o r to taking on the next cargo unless the load-on-top (LOT) procedure i s u t i l i z e d . The LOT procedure consists of allowing the oil-water mixture to separate, then pumping the water out u n t i l the oil-water interface i s reached. The o i l slops are kept on board, and the next cargo i s merely added on top. I t i s up to the refinery to deal with the problem of removing the remaining s a l t water from the cargo. The e f f i c i e n c y of LOT varies with the weather conditions (since rough weather makes separation of the o i l and water phases more d i f f i c u l t ) and with the degree of care taken i n the pumping operation. The reduction i n o i l p o l l u t i o n r e s u l t i n g from adoption of LOT procedures i s estimated to vary from 80% ( P o r r i c e l l i et a l , 1971) to 99% (Kirby, 1968; Holdsworth, 1971) depending on these parameters. About 80% of the tanker f l e e t makes use of LOT (Victory, 1973). Non-adherence occurs for several reasons: 1. Irresponsible operation. 2. The delivery of crude to smaller r e f i n e r i e s which refuse to accept salt-contaminated residues. 3. Short passages i n which there i s i n s u f f i c i e n t time f o r separation of o i l and water to occur. 4. Combination c a r r i e r s , which may carry crude followed by ore or grain. 5. Carrying of f u e l o i l cargoes, which cannot be contaminated with s a l t water since the f u e l i s not further refined before use. 6. Entering dry dock, which requires precleaning of a l l tanks. 21 FIGURE 5: The Growth of Crude Oil Transport fay Sea The graph shows the exponential increase in the amount transported by sea as well as the increase in the percentage of total o i l transported which is crude instead of refined products. The maps show changes in tanker routes. The width of the path is proportional to the amount transported. Since the closing of the Suez Canal in 1967, a substantial fraction of a l l traffic has been diverted from the Mediterranean to the Atlantic Ocean. (Figure from Butler et al, 1973, p.86.) 22 Some of these problems can be overcome by the provision of f a c i l i -t i e s i n ports for the reception of o i l residues (IMCO, 1972). For further reference to LOT and i t s problems, see Kirby (1968), Holdsworth (1971), P o r r i c e l l i et a l (1971) and Victory (1973). The international regulations are dealt with i n IMCO (1972) and IMCO (1973a). Referring again to Table 6, the next transportation source i s 'Terminal operations'. This has been estimated from two studies of the M i l -ford Haven tanker terminal i n B r i t a i n (Dudley, 1968; Dudley, 1971). I t i s too small a source to be s i g n i f i c a n t i n the context of open ocean p o l l u t i o n . The fourth source i s l i s t e d as "Bilges, bunkering'. 'Bilges' refers to, o i l which reaches ship bilges and eventually the ocean. I t i s generally of a dissolved and thin s l i c k nature which does not form persistent o i l po l l u t i o n . 'Bunkering' refers to the f u e l l i n g of ships. O i l p o l l u t i o n results from spillages when fueling, which contribute to harbour but not open ocean p o l l u t i o n . Tanker accidents contribute 0.2 mta, and a l l ship accidents contribute 0.3 mta of petroleum to the marine environment. This i s only 23% of the amount l o s t by operational discharges each year, but of course the losses are l o c a l i z e d and dramatic, and so at t r a c t p u b l i c i t y . The nature of tanker accidents has been investigated by P o r r i c e l l i et a l (1971), Keith and P o r r i c e l l i (1973), and Wardley Smith (1973). O i l s p i l l a g e i s primary due to structural f a i l u r e s (48% of t o t a l outflow), which generally occur offshore, and groundings (28% of t o t a l ) , which, not too su r p r i s i n g l y , tend to occur near shore (Keith and P o r r i c e l l i , 1973). CHAPTER 3 23 WEATHERING OF PETROLEUM IN THE MARINE ENVIRONMENT I n t r o d u c t i o n Both the chemical composition of petroleum and i t s sources to the marine environment have a l r e a d y been discussed- The long-term f a t e of t h i s petroleum depends on a v a r i e t y of environmental f a c t o r s which combine to 'weather' the o i l . The environment may a l t e r the s t a t e of the o i l p u r e l y by p h y s i c a l l y d i s t u r b i n g i t , causing . e m u l s i f i c a t i o n or s i n k i n g . This I term p h y s i c a l weathering - no change i n the chemical composition of the o i l takes place. Chemical weathering, on the other hand, r e f e r s to environmental a l t e r a t i o n of the chemical composition of the o i l , such as by evaporation, d i s s o l u t i o n , a u t o - o x i d a t i o n , and biodegradation. Each of these weathering processes and i t s e f f e c t on o i l i n the marine environment i s discussed below. P h y s i c a l Weathering: E m u l s i f i c a t i o n Two types of emulsion occur as a r e s u l t of turbulence and a g i t a t i o n of o i l at sea by wind, wave, and t i d e a c t i o n : o i l - i n - w a t e r emulsions i n which water i s the main phase, and w a t e r - i n - o i l emulsions i n which o i l i s predomin-ant. O i l - i n - w a t e r emulsions c h a r a c t e r i s t i c a l l y c o n s i s t of f i n e d r o p l e t s of o i l , 5 pm to s e v e r a l mm i n diameter ( F o r r e s t e r , 1971), d i s p e r s e d through the water column to an extent dependent on the v i o l e n c e of the turbulence. A l l o i l s w i l l form o i l - i n - w a t e r emulsions given s u f f i c i e n t a g i t a t i o n , but they are of l i m i t e d s t a b i l i t y : f i n e d i s p e r s i o n s c o n t a i n i n g about 1 ppm o i l w i l l p e r s i s t f o r s e v e r a l weeks; d i s p e r s i o n s of 30 ppm and above separate out i n a matter of h a l f an hour (Parker et a l , 1971). B a c t e r i a l growth on the o i l a i d s i n i t s e m u l s i f i c a t i o n and enhances i t s s t a b i l i t y , a pparently because the metabolic products possess p r o p e r t i e s of s u r f a c t a n t s ( Z a j i c and 24 Supplisson, 1972). In o i l s p i l l situations, detergents have been widely used (e.g. Smith, 1968); they function as emulsifying agents, and maintain the o i l in a stable emulsion (Silsby, 1968). Oil-in-water emulsions tend to be more toxic than slicks, since higher concentrations of hydrocarbons are dispersed into the water column. However, as a result of the greatly increased surface area of the o i l as an emulsion, the rate of degradation increases, ingestion and sedimentation of the fine droplets by fi l t e r feeding zooplankton can occur,"" and association of droplets with detritus results in sedimentation (Parker et al, 1971). Water-in-oil emulsions also occur. Only oils which contain the asphaltic components of crude will form such emulsions (Berridge et al, 1968), but they can form spontaneously and be extremely stable. The water content is usually about 80% (Berridge et al, 1968), with the rate of formation under similar conditions varying widely between crudes depending on their asphaltic content (Dodd, 1971). The agent causing emulsification was isolated but not fully identified by Mackay et al (1972) as a type of asphaltenic compound. Water-in-oil emulsions are extremely viscous: the viscosity of the emulsion formed by the Bunker C o i l spilled in the 'Arrow' accident was 30,000 poise (32°F) compared with 700 poise for the original o i l (Mackay et al, 1973). These stable,viscous emulsions pose intractable problems in o i l spill cleanup. The emulsion formed by the crude o i l spilt in the 'Torrey Canyon' accident became notorious and a household word as 'chocolate mousse'. Tank washing and pumping operations on tankers are ideal for the formation of water-in-oil emulsions (Holdsworth, 1970), so that tank washings are discharged as stable lumps of emulsion. This reduces the surface area drastically, since the o i l would otherwise exist as a slick. Photo-oxidation is severely limited; evaporation and dissolution are hindered. Biodegradation is the only process which is available to degrade the o i l . It proceeds because of the water available to encourage b a c t e r i a l growth within the micro-environment of the emulsion (Kinney et a l , 1969). Since the degrad ti o n by bacteria i n a nutrient-poor s i t u a t i o n i s very slow, w a t e r - i n - o i l emulsions form longlived pollutants that t r a v e l the seas as tar lumps. These w i l l be further discussed i n Chapter 5. 26 Sedimentation The specific gravity of crude oils varies from 0.75 to 1.0; and sea water from 1.024 to 1.030. Thus virtually a l l crude oils, and a l l refined products except for the heaviest of residual oils, will float at sea. However, the various weathering processes a l l act to increase the density of o i l . Water-in-oil emulsification immediately increases the density of the emulsi-fied lump to a weighted average of the o i l and seawater. Evaporation and dis-solution, preferentially remove the lighter components up to boiling points of about 370°C. The residual of crude o i l boiling above 370°C has a density about 10% greater than the original crude (see Table 5). Bacterial degrada-tion preferentially removes the paraffins (Blumer et al, 1973), which are the lightest class of compounds, and so further increases its density. The actual cell weight of the bacteria also increases the density of the oil-bacterial mass. Spooner (1971) reported that bacteria created a brew of approximately neutral buoyancy in laboratory experiments, and after several weeks found the oi l largely on the bottom, entangled with bacterial masses. Kinney et al (1969) observed the same of water-in-oil emulsions in the natural environment. Actual fouling growth on floating tar can increase its density to the point that i t sinks. The fouling community can become quite large and varied - see Chapter 5 - but is doomed by its own luxurious growth. In coastal areas the sorption of o i l onto s i l t and detritus may lead to sedimentation (Lisitzin, 1972; Spooner, 1970). Furthermore, fine grained clay minerals can absorb or adsorb dissolved hydrocarbons from the water column (Suess, 1968; Meyers, 1972). Sedimentation may also occur for indirect reasons. Filter-feeding zooplankton can injest dispersed droplets of o i l and sediment them in their feces (Parker et al, 1971; Conover, 1971). The rate at which this form of 27 sedimentation occurs depends on a variety of factors, but i s s i g n i f i c a n t and can reach 0.3 g/m /day (Parker et a l , 1971). Whatever the mechanism, sedimentation of o i l does occur. Marumo and Kamada (1973), Kinney et a l (1969), Morris (1963) among others have observed tar below the surface hovering at neutral bouyancy. Blumer and Sass (1972) documented the incorporation of o i l into the sediments a f t e r the 'Florida' s p i l l , as did Kolpack et a l (1971) after the Santa Barbara s p i l l . The sinking of o i l has received attention and some use as a method of dealing with o i l s p i l l s . A v a r i e t y of materials which are o l e o p h i l i c and dense enough to sink o i l are available. The method i s reviewed by Brown (1971) and tests of various materials are summarized and evaluated by Houston et a l (1972). 28 Chemical Weathering - Evaporation Evaporation p r e f e r e n t i a l l y removes the low-boiling components of o i l . Since the vapour pressures of hydrocarbons decrease l o g a r i t h i m i c a l l y with increasing carbon number(see Table B ) , the evaporative losses decrease rapidly for higher members of homologous series. L i t t l e or no f r a c t i o n i z a -t i o n w i l l occur between hydrocarbons of the same v o l a t i l i t y that belong to different s t r u c t u r a l families (Blumer et a l , 1973a). Simulated evaporation experiments i n the laboratory (Krieder, 1971) indicate that a l l hydrocarbons containing less than about 15 carbon atoms (boiling point 270°C) v o l a t i l i z e i n about 10 days from a 0.5 mm s l i c k . Hydrocarbons i n the C-15 to C-25 range (boi l i n g range 270°-400°C) show li m i t e d v o l a t i l i t y and are retained for the most part. Above C-25 (b o i l i n g point above 400°C) there i s very l i t t l e loss (see Figure 6). These r e s u l t s are simil a r to those obtained by Lieberman (1973), again with simulated weather-ing apparatus, who found v i r t u a l l y a l l evaporation from #4 and #5 f u e l o i l s occurred within 10 days. In the natural environment the rate of evaporation may be much fast e r , but with the same ultimate r e s u l t s : Smith and Maclntyre (1971) found greater evaporation i n s i x hours at sea than i n 40 hours i n a labora-tory bubbler apparatus, and Sivadier and Mikolaj (1973) showed that natural seep o i l l o s t the majority of i t s v o l a t i l e fractions i n 1-2 hours i n sea state four conditions. The rate of evaporation i s dependent mainly on wind speed and a i r temperature, with water temperature only a minor factor (Frankenfeld, 1973b). Whitecapping aids evaporation, producing a large loss of low-boiling compounds (Smith and Maclntyre, 1971). The rate of evapora-tion i s also increased by the spreading of an o i l s l i c k (Hoult, 1972). Whatever the rate of evaporation, there i s a clear trend for rapid i n i t i a l evaporation, and asymptotic approach to an ultimate weight loss 29 FIGURE 6: Simulated Weathering of Crude Oil 2.5r FIGURE 7: Evaporative Weight Loss of Natural Seep Oil as a Function of Time for Open Sea Tests • • (From Sivadier and Mikolaj, 1973, p. 483). 30 ( S i v a d i e r and M i k o l a j , 1973; see f i g u r e 7). A l l s t u d i e s agree t h a t evapora-t i o n i s slow to a f f e c t any hydrocarbons above C-15 ( b o i l i n g p o i n t 270°C), and t h a t , above about C-23 ( b o i l i n g p o i n t 380°C), the e f f e c t s of evaporation are i n s i g n i f i c a n t (Blumer et a l , 1973a; Brunnock et a l , 1968). The r e s u l t a n t e f f e c t of evaporation on an o i l i s thus very much dependent on i t s b o i l i n g p o i n t composition. Evaporation alone w i l l remove l e s s than 10% of a heavy r e s i d u a l o i l , up to 50% of a crude o i l , about 75% of #2 f u e l o i l , and v i r t u a l l y a l l of k e r o s i n e and g a s o l i n e (Petroleum i n the Marine Environment, 1975). In comparison w i t h other weathering processes, evaporation i s the most important process f o r the f i r s t 1-3 days when evaporation i s very r a p i d (Frankenfeld, 1973b). D i s s o l u t i o n competes d i r e c t l y w i t h evaporation, a f f e c t i n g the same compounds, but i s d e f i n i t e l y l e s s than 50% of the r a t e of evaporation, and perhaps as low as 1% (H a r r i s o n et a l , 1975). T h e o r e t i c a l treatments of evaporation have been proposed. Blokker (1964) and Hoult (1971) a r r i v e d a t p r e d i c t i v e models f o r o i l s l i c k s which gave good agreement w i t h experimental data from wind tunnel s i m u l a t o r s when the weight l o s s was grea t e r than 15%. B u t l e r (1975) has proposed a model f o r evaporative weathering of petroleum r e s i d u e s such as t a r lumps. Sem i q u a n t i t a t i v e agreement was obtained f o r crude o i l s weathered a r t i f i c i a l l y , and crude r e s i d u e s weathered on rocky shores. A p p l i c a t i o n of the model to ta r lumps r e q u i r e d that t a r be fragmented from much l a r g e r and o l d e r masses. 31 D i s s o l u t i o n The e f f e c t s of d i s s o l u t i o n on the chemical composition of o i l i s q u a l i t a t i v e l y s i m i l a r to evaporation - the l o w - b o i l i n g components, which are a l s o the most so l u b l e , are p r e f e r e n t i a l l y removed. Under n a t u r a l c o n d i t i o n s , the r a t e of evaporation i s c o n s i d e r a b l y g r e a t e r than the r a t e of d i s s o l u t i o n ( H a r rison et a l , 1975). However, d i s s o l u t i o n has importance not o n l y as a weathering process, i n which i t s r o l e i s l i m i t e d , but a l s o because i t i s the d i s s o l v e d compounds which reach marine b i o t a and are r e s p o n s i b l e f o r o i l ' s t o x i c i t y . The s o l u b i l i t i e s of hydrocarbons drop d r a s t i c a l l y w i t h i n c r e a s i n g carbon number (see Table 8 ) . For example, the s o l u b i l i t y of pentane i s 27.6 ppm and of decane i s 0.052 ppm, a decrease of about an order of magni-tude f o r each two carbon atoms added. The r e l a t i o n s h i p i s t h a t , f o r each homologous s e r i e s , the s o l u b i l i t y i n water i s a l i n e a r f u n c t i o n of the hydro-carbon molar volume ( M c A u l i f f e , 1966). For hydrocarbons w i t h the same number of carbon atoms the s o l u b i l i t y i n c r e a s e s i n the order: n-alkanes, i s o - a l k a n e s , c y c l o p a r a f f i n s , and aromatic hydrocarbons. The high-molecular weight NSO compounds which occur i n petroleum, although s u r f a c e a c t i v e , are apparently not a p p r e c i a b l y more soluble • than hydrocarbons of comparable molecular weight (Koons, 1973). The s o l u b i l i t i e s of hydrocarbons are enhanced by the presence of n a t u r a l d i s s o l v e d organic matter i n seawater (Boehm and Quinn, 1973). The competing process of evaporation and d i s s o l u t i o n l e a d to a f r a c t i o n a t i o n of the d i s s o l v i n g petroleum that cannot be p r e d i c t e d p u r e l y by s o l u b i l i t i e s . Smith and Maclntyre (1971) found that medium molecular weight aromatics, p a r t i c u l a r l y the methyl- and dimethyl-naphthalenes, com-p r i s e d the g r e a t e s t p r o p o r t i o n of the d i s s o l v e d o i l , whereas the s a t u r a t e d hydrocarbons were not d e t e c t a b l e . These r e s u l t s can be a t t r i b u t e d to the f a c t that the d i s s o l u t i o n of the low-molecular weight p a r a f f i n s and aromatics i s o f f s e t by t h e i r h i g h r a t e of evaporation, whereas the d i s s o l u t i o n of the high-molecular weight aromatics, the medium and the high-molecular weight p a r a f f i n s i s l i m i t e d by t h e i r s o l u b i l i t y . (Medium weight p a r a f f i n s are much l e s s s o l u b l e than medium weight aromatics: decane s o l u b i l i t y i s 0.052 ppm whereas the corresponding aromatic, naphthalene, i s 31.2 ppm s o l u b l e . ) Thus, of the major groups of hydrocarbons, medium molecular weight aromatics have the best combination of s o l u b i l i t y and v o l a t i l i t y f o r en t e r i n g the water column. Anderson et a l (1974) a l s o have documented the enriched aromatic content of the w a t e r - s o l u b l e f r a c t i o n of o i l . Comparing the r a t i o of aromatics to p a r a f f i n s i n the w a t e r - s o l u b l e f r a c t i o n t o the r a t i o i n the o r i g i n a l o i l , they c a l c u l a t e d 'aromatic enrichment f a c t o r s ' ranging from 15 to 125 f o r two crudes, Bunker C, and #2 f u e l o i l . Over longer time p e r i o d s , the processes of b i o d e g r a d a t i o n and photo - o x i d a t i o n begin to a f f e c t the o i l , causing o x i d a t i o n of hydrocarbons to a l c o h o l s , aldehydes, and a c i d s , a l l of which are more s o l u b l e than the parent hydrocarbons. For i n s t a n c e , n-octane ( s o l u b i l i t y 0.43 ppm) can be o x i d i z e d to<K-octanol ( s o l u b i l i t y 600 ppm; S e i d e l l , 1941), and naphthalene (31 ppm) to tvr-naphthol (740 ppm; S e i d e l l , 1941). F r a n k e n f e l d (1973 a and b ) , using a weathering s i m u l a t o r , demonstrated that d i s s o l v e d o r g a n ics i n c r e a s e w i t h weathering, and determined that the increased d i s s o l v e d o r g a n i c s were c h i e f l y oxygenated aromatics. 33 TABLE 8 : Melting Points, Boiling Points, Vapour Pressures, and Solubilities of Selected Hydrocarbons  Melting points were taken from the Handbook of Chemistry and  Physics, 55th Edition, CRC Press, 1974-75. Vapour pressures were obtained from the Handbook and from Wilhoit and Zwolinski (1971). Antoine's equation was used to determine vapour pressures at 25°C. A graph of vapour pressure as a function of carbon number is presented in Appendix A. Solubilities were obtained from a variety of sources: Sutton and Calder (1974); McAuliffe (1963, 1966, and 1974); Price (1973): and Bohcn and Claussen (1951). When more than one value appeared in the literature for solubility at 25°C, the most recent value was taken. When solubilities in sea water were available, they were quoted and indicated by an asterisk. Otherwise, values are for distilled water. Hydrocarbon solubilities in sea water are probably not more than 12 to 30% lower than those in distilled water (Harned and Owen, 1958). The information in this table was assembled by Wendy Richardson under contract to Ocean Chemistry, Ocean and Aquatic Sciences, Department of Environment, Victoria, B.C., Canada. 34 NORMAL PARAFFINS NAME FORMULA MELTING PT. (°C) BOILING PT. (°C) V.P. at 25°C (atmospheres) SOLUBILITY @25°C ppm (wt/wt) pentane C5H12 -129.7 36.1 6.75xl0-1 27.6* hexane C6H14 -95 68.9 1.99xl0-1 ,• 9.5 . heptane C7 H16 -90.6 98.4 6.03xl0~2 2.2 octane C8H18 -56.8 125.7 1.86xl0~2 .43 nonane C9 H20 -51 150.8 5.64xl0~3 .12 decane C10H22 -29.7 174.1 1.72xl0~3 .052 undecane C11H24 -25.6 195.9 3.15xl0~4 dodecane C12H26 -9.6 2.6.3 1.55xl0~4 .0029* tridecane C13H28 -5.5 235.4 4.37xl0~5 tetradecane C14H30 5.9 253.7 1.26xl0~5 .0017* pentadecane C15H32 10 270.6 3.46xl0~6 hexadecane C16H34 18.2 287 8.85xl0~7 .0004* heptadecane C17H36 22 301.8 2.67xl0~7 •octadecane C18H38 28.2 316.1 7.34xl0~8 .0008* eicosane C20H42 36.8 343 2.15xl0~9 .0008* hexacosane C26H54 56.4 412.2 -14 7.22x10 .0001* * indicates solubility in sea water, a l l others are solubilities in distilled water. 35 ISOPARAFFINS SOLUBILITY MELTING BOILING V.P. at 25°C *25°C ppm NAME FORMULA PT. (°C) PT. (°C) (atmospheres) (wt/wt) 2-methylpentane C6H14 -153. 7 60.3 2.76xl0_1 13.0 3-methylpentane C6H14 63.3 2.50X10"1 13.1 2-me thylhexane C7 H16 -118. 3 90 8.67xl0~2 2.5 3-methylhexane C7 H16 -119 92 8.10xl0~2 2.6 2-methylheptane C8H18 -109 117.7 2.71xlO"2 3-methylheptane C8H18 115.8 2.57xl0~2 • 79 4-methylheptane C9H20 -113. 2 142.4 8.91xl0~3 .11 36 CYCLOPARAFFINS SOLUBILITY MELTING BOILING V.P. at 25°C @25°C ppm NAME FORMULA PT.(°C) PT. (°C) (atmospheres) (wt/wt) cyclopentane C5 H10 -93.9 49.3 4.18x10*1 160 methylcyclopentane C6 H12 -142.4 71.8 1.81xl0_ 1 29. 2* cyclohexane C6 H12 6.55 80.7 1.28xl0_ 1 67. 5 methylcyclohexane C7 H14 -126.6 100.9 6.10xl0- 2 16 ethylcyclopentane C7 H14 -138.4 103.5 5.25xl0~2 1,trans-4-dimethylcyclohexane C8 H16 -37.0 119.3 2.98xl0- 2 3. 84 l,cis-3-dimethylcyclohexane C8 H16 -75.6 120.1 2.83xl0~2 l,cis-2-dimethylcyclohexane C8 H16 -50.1 129.7 1.90xl0~2 6. ,0 ethylcyclohexane C8 H16 -111.3 131.8 1.68xl0~2 propylcyclopentane C8 H16 -117.3 131.0 1.62xl0~2 2. .0 * indicates solubility in sea water, a l l others are solubilities in distilled water. 37 AROMATICS NAME FORMULA MELTING PT. (°C) BOILING PT. (°C) V.P. at 25°C . (atmospheres) SOLUBILITY C?25°C ppm (wt/wt) benzene w 5.5 80.1 1.25xl0_ 1 1391* toluene C7 H8 -95 110.6 3.74xl0~2 402* ethylbenzene C8 H10 -94.5 136.2 1.25xl0~2 152 p-xylene C8 H10 13.3 138.4 1.15xl0~2 157 m-xylene C8 H10 -47.9 139.1 1.09xl0~2 134 o-xylene C8 H10 -25.2 144.4 8.71xl0- 3 167 Isopropylbenzene C9 H12 -96 152.4 6.03xl0~3 48.2 n-propylbenzene C9 H12 -99.5 159.2 4.43xl0~3 l-methyl-3-ethylbenzene C9 H12 3.86xl0- 3 1,2,4-triroethylbenzene C9 H12 -43.8 169.4 2.67xl0~3 51.9 isobutylbenzene <?10H14 -51.5 172.8 2.45xl0~3 10.1 1,2,3-trimethylbenzene C9 H12 -25.4 176.1 1.96xl0~3 1,2,4,5-tetramethylbenzene C10 H14 79.2 196.8 6.50xl0- 4 3.48 naphthalene C10 H8 80.6 218 3.07xl0"4 31.2 1,2,3,4-tetramethylbenzene C10 H14 -6.2 205 4.44xl0~A biphenyl C12 H10 71 255.9 7.08 acenaphthalene C12 H10 96.2 279 3.88 fluorene C13 H10 116 293 1.90 phenanthrene C14 H10 101 340 9.56xl0~7 1.18 anthracene C14 H10 216.2 340 2.68xl0~6 .075 * indicates solubility in sea water, a l l others are solubilities in distilled water. 38 Vapour Pressures of Hydrocarbons as a Function of Carbon Number N I I l I I i i—i—<s—i—i—i—L 6 7 8 9 10 11 12 13 14 15 16 17 18 N The regression line predicts log 1 AP for normal alkanes within 95T° confidence limits of + 0.08 . (From Butler, 1975b, p. 11) 39 Biological Degradation Introduction: The literature dealing with the microbial degradation of hydrocarbons is extensive. The original interest in the problem was purely academic and scientific. It was first noticed in 1895 that bacteria degrade the supposedly inert paraffin used as a support in cultures, and over the years much work was done, usually using pure hydrocarbons under culture conditions. A large body of literature now exists dealing with the types of hydrocarbons attacked and the pathways of oxidation. This literature has been reviewed by Zobell (1946), Treccani (1965), McKenna and Kallio (1965), and Van der Linden and Thijsse (1965). A second source of interest in petroleum microbiology originated from the discovery that microbes could be used to prospect for petroleum. It was also discovered that microbes caused decomposition of petroleum and refined products, especially jet fuels, under storage conditions, and that this decomposition also led to tank and pipe corrosion. These discoveries, and the interest in establishing the genesis of petroleum, inspired an extensive investigation into petroleum microbiology by the rapidly growing petroleum industry. This body of knowledge has been reviewed by Davis (1967). Thirdly, and most recently, interest in the microbial degradation of hydrocarbons has come from increased environmental awareness and the burgeon-ing problem of o i l spills, particularly in the marine environment. Some recent literature deals specifically with this problem, using mixed cultures with crude and refined oils, and attempting to understand the microbial ecology of the hydrocarbon oxidizers in the marine environment (Zobell, 1969 and 1973; Atlas, 1972; Floodgate, 1972). 40 Hydrocarbon Degradation: I t has been e s t a b l i s h e d t h a t microbes w i l l a t t a c k the spectrum of hydrocarbons from a l i p h a t i c to aromatic (e.g. T r e c c a n i , 1965). Alkanes are p r e f e r e n t i a l l y degraded, and aromatics more r e s i s t a n t ( Z o b e l l , 1969). W i t h i n each hydrocarbon c l a s s the very l i g h t e s t components, such as C-5 to C-8 i n the p a r a f f i n s , cyclohexane, toluene, and phenol, are b a c t e r i c i d a l or b a c t e r -i o s t a t i c to most species (Klug and M a r k o v i t z , 1971; McKenna and K a l l l o , 1964).~ The medium molecular weight compounds are most e a s i l y a t t a c k e d , and the high molecular weight compounds become i n c r e a s i n g l y more r e s i s t a n t , apparently because t h e i r v e r y low s o l u b i l i t i e s present a l o g i s t i c a l problem to the micro-organisms ( Z o b e l l , 1969). H i g h l y condensed c y c l i c hydrocarbons, asphaltenes, and non-hydrocarbon NSO compounds are e s p e c i a l l y r e c a l c i t r a n t ( B a i l e y et a l , 1973). The i s o p a r a f f i n s do not f i t i n t o t h i s scheme. I t has been shown that the ease of degradation of i s o p a r a f f i n s i s v ery much dependent on the extent of branching. For i n s t a n c e , one methyl group attached to an alkane slows the r a t e of degradation. Two methyl groups on the same carbon atom, e s p e c i a l l y i f they are on the penultimate carbon atom, e s s e n t i a l l y b l o c k degradation (McKenna and K a l l i o , 1964). Thus the i s o p r e n o i d s p r i s t a n e and phytane, which each have fo u r methyl branches, are much more s l o w l y degraded than the corresponding alkanes. Indeed, i t appears that degradation of p r i s t a n e and phytane i n a mixed c u l t u r e does not occur u n t i l the alkanes have been exhausted ( B a i l e y et a l , 1973). The mechanisms of degradation have been worked out i n some d e t a i l (Van der Linden and T h i j s e , 1965; T r e c c a n i , 1965; McKenna and K a l l i o , 1965). The d e t a i l of the mechanisms i s much too voluminous to summarize here; s u f f i c e i t to say that the products of degradation are p r i m a r i l y a l c o h o l s , aldehydes, and a c i d s , but a l s o i n c l u d e hydroperoxides, ketones, and e s t e r s ( Z o b e l l , 1973). 41 Some of the degraded hydrocarbons are mineralized to carbon dioxide and water, and the remainder are assimilated to form bacterial biomass, or remain as intermediate products (Atlas and Bartha, 1972 a, b) . Figure 8 shows the effect of a mixed population of micro-organisms on a crude o i l under culture conditions. Types of Micro-organisms: Over 200 species of bacteria, yeasts, and filamentous fungi have been shown to metabolize one or more kinds of hydrocarbons. These species are diversified, being drawn from 28 genera of bacteria, 30 genera of fungi, and 12 of yeasts (Zobell, 1973). No single species of micro-organism has been found capable of attacking the f u l l range of hydrocarbons. Instead, there is a great deal of specialization, and most effective degradation of a crude o i l occurs with :.mixed cultures (Soli and Bens, 1972). The single most successful hydrocarbon-degrader which has been isolated is the fungus Cladosporium resinae (Cooney and Walker, 1973). Certain species, such as C. resinae, have constitutive enzymes for hydrocarbon degradation, but more commonly the enzymes are inducible (Zobell, 1973). Ecology of Hydrocarbon-degraders in the Marine Environment: Degradation of hydrocarbons is primarily an aerobic process. Some anaerobic degradation can occur, but the rates are apparently very slow (see Floodgate, 1972). The hydrocarbons provide a carbon and energy source for microbes. However, a great many environmental factors, and some nutritional requirements, influence the rate at which degradation will occur. Since most work of hydro-carbon degradation is done under culture conditions, which are optimal, there 42 FIGURE 8: Gas Chromatograms of Crude O i l Degraded by Incubation with a Mixed Population of Micro-organisms  IX H 1—I—I —I I I I I I I I I I I I I I 80* 80* 15 20 25 30 EQUIVALENT CARBON N U M B E R S I I I | I I I | I I I | . 160* 240* 320* OVEN TEMPERATURE °C Gas chromatograms of crude o i l at 0-time (top), a f t e r 6 hours (centre), and 26 hours (bottom) of incubation with a mixed population of micro-organisms. Note change i n attenuation i n top chromatogram. (From Mechalas et a l , 1973, p. 71)., 43 is not a great deal known about the influences of the various environmental factors, but some basic information has been obtained. Hydrocarbon-degrading microbes are common in near shore waters (Gunkel, 1973; Zobell, 1969) but the concentrations vary widely, depending primarily on the levels of contamination by hydrocarbons (Mironov, 1970b). In the open ocean, Zobell (1969) reports that only 5% of several hundred samples contained oil-oxidizing bacteria, and none contained oil-oxidizing molds or fungi. Anderes (1973) obtained hydrocarbon-utilizing bacteria in 24% of 173 samples but no molds or fungi. Despite these low concentrations in some environments, natural innoculation of o i l spills always seems to occur, with complete colonization occurring within 1-2 weeks (Pilpel, 1968). Pilpel concludes that there is l i t t l e to be gained by artificially innoculating o i l slicks. The environmental factor which most commonly limits the degradation of o i l in the marine environment is a shortage of nitrate and phosphate nutrients (Bridie and Bos, 1971; Atlas and Bartha, 1972b). These nutrients are always in short supply in the open ocean, and i t is not surprising that they limit growth in the intensive blooms of microbes which occur in o i l . A promising method of o i l s p i l l treatment is the addition to o i l slicks of an oleophilic nitrate- and phosphate-rich compound to encourage microbial degradation (Bartha, personal communication). Oxygen can theoretically be limiting to degradation since the BOD of o i l is high, especially i f i t is completely mineralized (Zobell, 1973). Oxygen does not appear to be the limiting factor in o i l slick situations where atmospheric oxygen is readily available (Friede et al, 1972). Oxygen limitation may, however, be a problem in areas of chronic o i l pollution where gas exchange is limited. Temperature also affects the rate of degradation. It has been established that o i l is degraded at a l l marine temperatures from -2°C up to as high as 70°C (Zobell, 1973). However, most species are active in the mesothermic range of 20° to 25°C, and degradation rates decrease markedly at lower temperatures. Psychrophilic bacteria oxidize o i l at -1.1°C at only 5 to 10% of the rate of mesothermic species at 25°C (Zobell, 1973). Kator et al (1971) found that oxidation of paraffins was proportional to the incubation temperature, doubling with an increase of 10°C. Increasing depth reduces microbiological activity. In fact, petro-leum residues deposited at several thousand meters depth may remain 'preserved' indefinitely (Jannasch and Eimhjellen, 1972). Finally, the concentration of dissolved petroleum may be important to the rate of its microbial oxidation. In fact, there may be a threshold concentration below which autochthonous bacteria are unable to utilize dis-solved hydrocarbons as a substrate (Jannasch, 1969). For masses of o i l , the rate of microbial oxidation is very dependent on the surface area available to microbiological attack. Various other factors influence the rate of degradation, such as: salinity; pH; turbulence; other organic matter; microbial predators; and accumulation of intermediate products. The relative effects of a l l these parameters have not been unravelled. The net result of these various environmental factors determines the rate at which o i l degrades in the marine environment. Measurements of the net degradation rate are of great interest, but are not common. The only direct observation of biological degradation is by Blumer et al (1973), who observed the partial biodegradation of stranded crude o i l in the intertidal environment over a 16 month period. Other publications, such as Blumer and Sass (1972b), give an indirect idea of the rate of degradation. It is one of the purposes of this thesis to provide information on the rates of 45 biodegradation i n the marine environment. M a c r o b i o l o g i c a l Degradation: We have so f a r ignored any r o l e which might be played by macro-organisms i n the metabolism of o i l . V arious marine organisms have been observed to take up d i s s o l v e d and p a r t i c u l a t e hydrocarbons from sea water (Lee 1972a, b, 1975; Stainken, 1975; Neff and Anderson, 1975; Conover, 1971). Lee r e p o r t s that v a r i o u s d i s s o l v e d polyaromatic hydrocarbons are taken up by zooplankton, mussels, and f i s h . I n some cases the hydrocarbons are meta-b o l i z e d , and i n other cases d i s s o l v e d hydrocarbons are merely stored»: and •,.: , rele a s e d i n t o c l e a n water (Lee, 1972a; b; Neff and Anderson, 1975). P a r t i -c u l a t e hydrocarbons appear to pass d i r e c t l y through zooplankton i n t o t h e i r feces (Conover, 1971). I t i s evident that v a r i o u s macro-organisms are capable of metabol-i z i n g v a r i o u s f r a c t i o n s of o i l . However, from the p o i n t of view of c o n t r i -b u t i n g to the o v e r a l l degradation of o i l i n the marine environment the r o l e of macro-organisms must be assumed to be s m a l l . This statement i s based l e s s on experiment than on an a p p r e c i a t i o n of the microbes, w i t h t h e i r enormous r e p r o d u c t i v e c a p a b i l i t i e s , as the primary degraders and m i n e r a l i z e r s i n the environment. 46 Auto-Oxidation Chemical weathering of o i l can occur purely by chemical reaction of o i l with atmospheric oxygen. The process can be i n i t i a t e d either thermally or by photolysis. Under the thermal regime of the oceans, thermal reaction i s extremely slow, so that, when there i s reasonable exposure of o i l to l i g h t , photolysis i s the main process. The absorption of l i g h t , or the thermal decomposition of impurities, creates free r a d i c a l s . A chain reaction follows, since the products of reactions (hydroperoxides) themselves decompose to form more free r a d i c a l s (Parker et a l , 1971). These oxidation reactions are strongly catalysed by ions of variable valence, such as vanadium. They are i n h i b i t e d by sulfur compounds due to the chain-breaking reactions of sulphoxide formation (Berridge et a l , 1968). The oxidation reactions may proceed i n two d i f f e r e n t ways. The hydroxy compounds formed by decomposition of peroxides may undergo further dehydrogenation to y i e l d aldehydes, ketones and acids. A l t e r n a t i v e l y , pro-ducts of higher molecular weight may be formed by combination, condensation, or e s t e r i f i c a t i o n (Parker et a l , 1971). The products of lower molecular weight are much more soluble than the parent hydrocarbons (see d i s s o l u t i o n section) and so are rapidly removed from the s l i c k . Products of higher molecular weight are l i k e l y to form viscous gums or tars. The chain reaction process depends on the extraction of a hydrogen atom by a r a d i c a l . Therefore, hydrocarbon compounds containing weakly-bound hydrocarbon atoms should be p r e f e r e n t i a l l y oxidized. Since hydrogen atous bound t e r t i a r y carbons are more weakly bound than those attached to secondary carbons, isoparaffins should be s e l e c t i v e l y degraded ahead of paraffins, cycloparaffins, and aromatics (Berridge et a l , 1968). This conclusion i s based on th e o r e t i c a l considerations rather than experiment. Hansen (1975), working with a l i g h t f r a c t i o n of crude o i l , found experimentally that i s o p a r a f f i n s appeared to be p r e f e r e n t i a l l y photo-oxidized r e l a t i v e to p a r a f f i n s , but that aromatics were most e f f e c t i v e l y oxidized. He d i d not venture to explain t h i s phenomenon. Hansen also found that most of the photo-oxidation products were ca r b o x y l i c acids which appeared to be r e l a t e d to t h e i r parent hydrocarbons by the r e l a t i o n : C H + 0_ — C ,H _ COOH x y 2 x-1 y-2 The rate at which o i l i s photo-oxidized depends, l i k e everything else, on a number of f a c t o r s . The most important i s probably the surface area of the o i l . O i l spread as a t h i n f i l m obviously absorbs much more radiant energy than o i l lumped i n a w a t e r - i n - o i l emulsion. The experimental work which has been performed has dealt with o i l as a t h i n s l i c k . The experiments of Freegarde and Hatchett (1970) i n d i c a t e that complete photo-oxidation of a 2.5 um s l i c k would take about 100 hours of sun l i g h t , or 1 jum per 40 hours. Hansen (1975), on the basis of h i s experiments, made an estimate of about three years continuous sunlight to degrade a 0.4 mm s l i c k , which works out to 1 um per 100 hours. Both estimates i n d i c a t e that photo-l y s i s i s slow, even under the best of circumstances. The rate of photo-oxidation i s also very much dependent on the wavelengths of the i r r a d i a t i n g l i g h t . Both Hansen (1975) and Parker et a l (1971) obtained much f a s t e r degradation using shorter wavelengths than are found i n sunlight ( i . e . l e s s than about 300 nm). Hansen could get no degrad. t i o n to occur with wavelengths longer than 340 nm, and Parker et a l also found the most e f f e c t i v e p o r t i o n of sunlight was the u l t r a v i o l e t l i g h t of wavelength 300-350 nm. U l t r a v i o l e t l i g h t has a very high e x t i n c t i o n c o e f f i c i e n t i n the ocean and does not penetrate more than a very few meters (Parsons and Takahashi, 1973), so that any o i l dispersed below about two meters i n the water column should not undergo photo-oxidation. This has not been investigated experimentally. 48 T h i r d l y , the composition of o i l may a f f e c t the rate of degradation. Since s u l f u r compounds i n h i b i t the r e a c t i o n process, i t i s to be expected that h igh-sulfur o i l s should degrade more slowly than low-sulfur o i l s . F i n a l l y , the o p t i c a l density of the o i l i n the u l t r a v i o l e t region may be an important v a r i a b l e (Petroleum i n the Marine Environment, 1975). Neither of these l a s t two f a c t o r s have been studied. 49 Summary of Weathering A l l of the s i g n i f i c a n t weathering processes have been discussed i n some d e t a i l . However, the r e l a t i v e rates and e f f e c t s of the various mech-anisms have not been drawn in t o focus, and that i s the purpose of t h i s s e c t i o n . The processes of evaporation and d i s s o l u t i o n a f f e c t the l i g h t e s t components quickly, i n a matter of a few hours under most conditions, and then t h e i r e f f e c t diminishes exponentially. Of the two, evaporation i s u s u a l l y the dominant process, but d i s s o l u t i o n i s important f o r the aromatics of medium molecular weight, and f o r the products of oxidative degradation. Photo-oxidation and biodegradation are slower processes which take a matter of months to remove s i g n i f i c a n t q u a n t i t i e s of o i l under n a t u r a l conditions. They can ox i d i z e the f u l l spectrum of petroleum compounds, but since the l i g h t components are quickly removed by evaporation and d i s s o l u t i o n , they p r i m a r i l y a f f e c t the medium and heavy molecular weight compounds. M i c r o b i a l degradation p r e f e r e n t i a l l y removes the p a r a f f i n s , whereas photo-oxidation p r e f e r e n t i a l l y removes the i s o p a r a f f i n s . Of the two processes, biodegradation i s dominant i n s i t u a t i o n s where there are reasonable conditions f o r m i c r o b i a l growth. The i n t e r r e l a t i o n s h i p s between the various weathering processes as they a f f e c t a f l o a t i n g crude o i l s l i c k are i l l u s t r a t e d i n Figure 9. The rate at which the processes act i s very much dependent on the exposed surface area of the o i l . O i l spread as a very t h i n s l i c k allows the combined degrada-t i v e processes to work to maximum e f f e c t . This i s the reason the world's oceans are not covered by a t h i n f i l m of petroleum hydrocarbons. Conversely, o i l which i s lumped i n a w a t e r - i n - o i l emulsion i s not degraded e f f i c i e n t l y by any of these processes. In s i t u a t i o n s between these two extremes, the r e l a t i v e rates of the chemical weathering processes depend on the l o c a t i o n and state of the o i l i 50 FIGURE 9: Processes Leading to the Degradation of Crude Oil at Sea EVAPORATION AS SETTLING ON HEAVY PARTICLES DEGRADATION VERY SLOW DISCHARGE (From Parker et al, 1970, p. 238) The composition of the o i l i s also of great importance to the r e l a t i v e rates. Light refined o i l s are most affected by evaporation and d i s s o l u t i o n , whereas residual o i l s must wait for the slow oxidative pro-cesses to occur. The heaviest, asphaltic portion of petroleum i s v i r t u a l l y impervious to chemical weathering, and i n fact asphaltics are formed from l i g h t e r compounds during the weathering process. The asphaltic f r a c t i o n forms a long-lived, nearly i n e r t environmental pollutant. The fate of the isoprenoids pristane and phytane can be compared with the fate of the C-17 and C-18 n-alkanes to provide an analytic t o o l which reveals the r e l a t i v e rates at which an o i l i s affected by weathering processes. The b o i l i n g points of pristane and phytane are almost i d e n t i c a l to the C-17 and C-18 n-alkanes respectively. Thus the isoprenoids can be expected to evaporate at the same rate as the paraffins. However, the low molecular weight compounds C-17 and pristane are considerably more v o l a t i l e than C-18 and phytane (vapour pressures: C-17 = 2.7 x 10 ^atm.; C-18 =7.3 x 10 ^atm @ 25°C). Evaporation w i l l p r e f e r e n t i a l l y remove the more v o l a t i l e compounds so causing a decrease i n the C-17/C-18 and pristane/phytane r a t i o s i n the weathered o i l . The s o l u b i l i t i e s of the isoprenoids are not known, but can be inferred from t h e i r p o l a r i t y . They are, i f anything, s l i g h t l y less polar than the C-17 and C-18 n-alkanes a fact which i s experimentally demonstrated by the s l i g h t l y quicker rate at which the isoprenoids elute from polar columns i n gas chromatography (e.g. Bailey et a l , 1973; Ehrhardt and Blumer, 1972). The s o l u b i l i t y of the n-alkanes i s extremely low (0.0008 ppm), so the solu-b i l i t y of the isoprenoids i s presumably lower s t i l l . Dissolution i s , there-fore, very unlikely to be a s i g n i f i c a n t weathering process for any of these compounds. 52 Photo-oxidation i s expected to oxidize the isoprenoids preferen-t i a l l y . This has been experimentally v e r i f i e d by Hansen (1975) whose re s u l t s are summarized i n Table 9. No fra c t i o n a t i o n between compounds of the same class has been observed or i s expected. TABLE 9: Effect Crude of Photo-oxidation O i l on Isoprenoid/Alkane Ratios i n Hours of Irr a d i a t i o n pr/C-17 (%) ph/C-18 (%) 0 50.5 36.2 4 50.5 34.5 53 50.0 33.0 126 49.4 32.7 170 47.9 31.8 295 46.8 30.9 462 45.4 26.7 (From Hansen, 1975, p. 187). Microbiological degradation, i n contrast to photo-oxidation, pre-f e r e n t i a l l y removes the paraffins since the methyl groups on the isoprenoids impede degradation. This has been observed by many (e.g. Bailey et a l , 1973; Blumer et a l , 1973a). Again there i s no s i g n i f i c a n t f r a c t i o n a t i o n between compounds of the same class (Mechalas et a l , 1973). Three conclusions can be reached by observing the isoprenoid/ p a r a f f i n r a t i o i n o i l undergoing chemical weathering: 1) A decrease i n the pristane/phytane or C-17/C-18 r a t i o indicates evaporation i s occurring. 53 2) A n i n c r e a s e i n t h e C - 1 7 / p r i s t a n e and C - 1 8 / p h y t a n e r a t i o i n d i c a t e s t h a t p h o t o - o x i d a t i o n i s t h e d o m i n a n t p r o c e s s . 3) A d e c r e a s e i n t h e a l k a n e / i s o p r e n o i d r a t i o i n d i c a t e s m i c r o b i a l d e g r a d a t i o n i s t h e d o m i n a n t p r o c e s s . T h e s e c o n c l u s i o n s w i l l be u t i l i z e d t h r o u g h o u t t h e e x p e r i m e n t a l i n v e s t i g a t i o n s t o a s c e r t a i n t h e mechan i sms o f p e t r o l e u m d e g r a d a t i o n i n v a r i o u s s i t u a t i o n s . 54 CHAPTER 4 THE WEATHERING OF PETROLEUM UNDER CONTROLLED CONDITIONS Introduction An experiment was conducted under controlled conditions, by weather-ing o i l i n tanks, to provide a control for comparison with the f i e l d observa-tions. Gas chromatographic analyses were used to reveal the rate and mechan-isms of chemical weathering of the o i l samples. Experimental Method Three kinds of o i l were placed i n outdoor tanks 3 meters across, and % meter deep. Tanks were f i l l e d with seawater, and 5 gallons (23 1) of o i l were poured i n each tank, giving a layer of o i l about 3mm thick, and an oil-to-water r a t i o of 1 to 156. The o i l s used were an Alberta crude o i l , an intermediate f u e l o i l (Esso f u e l 46 which i s a #5 f u e l o i l ) , and die s e l f u e l . No exchange of water was provided, so that there was no source of nutrients for microbial growth and lim i t e d opportunity for d i s s o l u t i o n - chemical weathering was thus r e s t r i c t e d to evaporation and photo-oxidation. The tanks were l e f t undisturbed, except for occasionally siphoning out rainwater, from October 1973 to January 1974. Samples were taken from the tanks p e r i o d i c a l l y over this 3% month period and analysed by gas chromatography to determine the extent of chemical weather-ing that had occurred. For these analyses about 0.3 g of sample was dissolved i n 5 ml of carbon d i s u l f i d e and injected onto a Dexsil column programmed to 400 C. The instrumental parameters are given i n Table 18 . Representative chromatograms are presented i n Figures 10, 11, and 12. 55 FIGURE 10: Chromatograms of A r t i f i c i a l l y Weathered Crude O i l l ) Original crude 2) After 2 days 3) After 1 month 4 ) After 3 i months FIGURE 11: Chromatograms of an A r t i f i c i a l l y Weathered #5 , Fuel O i l 56 1) Original fuel o i l (Esso Fuel 46) 2) After 2.days 3) After 3h months FIGURE 12: Chromatograms of A r t i f i c i a l l y Weathered Diesel O i l 57 l ) Original diesel o i l 2) After 1 week 3) After 7 weeks 4) After 9 weeks Results of the Controlled Weathering Experiment The results of the controlled weathering experiment are summarized i n Table 10. The parameters l i s t e d there are calculated from the gas chroma-tograms. They are chosen to reveal the mechanisms by which the o i l i s chemi-c a l l y weathered during i t s 3% month exposure i n experimental tanks. The f i r s t 10% 50% two parameters, C r ° and C^ °, are measures of the shape of the envelope; they are defined as the equivalent n-paraffin carbon numbers at which the unresolved envelope reaches 10% and 50%, respectively, of i t s maximum amplitude. A high value of these parameters indicates a large loss of the low-boiling components making up the envelope, which i n turn indicates the extent of weathering by the evaporation and di s s o l u t i o n . The t h i r d parameter l i s t e d i n Table 10 i s the C-17/C-18 peak height r a t i o . Since the chromatograms do not separate the isoprenoids from the normal paraffins, the C-17 peak measures the amount of n-heptadecane and pristane, while the C-18 peak measures the amount of n-octadecane and phytane. A lower-ing of the C-17/C-18 r a t i o indicates the p r e f e r e n t i a l loss of the lower-boiling homologs, and so provides a measure of the extent of evaporation and d i s s o l u t i o n occurring at the b o i l i n g points of these compounds (302°C and 316°C). The C-18/C-19 r a t i o compares the r e l a t i v e amounts of phytane and nonadecane. Photo-oxidation and biodegradation are processes which act over much wider ranges of molecular weight than evaporation and d i s s o l u t i o n , but thei r effects are very much dependent on the structure of the hydrocarbons (see Chapter 3). Under microbial attack the isoprenoids are r e s i s t a n t , and the paraffins are p r e f e r e n t i a l l y removed, res u l t i n g i n an increase i n the C-18/ C-19 r a t i o . Photo-oxidation has the opposite e f f e c t , p r e f e r e n t i a l l y removing 59 the isoprenoids and so decreasing the C-18/C-19 ratio. Some ambiguity exists since, i f both photo-oxidation and biodegradation occur, their relative effects will tend to cancel. The final parameter in Table 10, the C-18/env. ratio re-duces the ambiguity by comparing the height of the C-18 peak to the height of the envelope. If both photo-oxidation and biodegradation are occurring, sub-stantial decreases in the C-18/env. ratio should occur. TABLE 10; Characteristics of Artificially Weathered Oils Length of Exposure cio% n ,c50% n C-17/C-18 C-18/C-19 C-18/env. Crude o i l original ind. ind. 1.60 1.25 .1.88 2 days 10.0 11.2 1.56 1.24 1.78 1 month 12.5 14.0 1.57 1.29 2.12 3% months 12.7 14.3 1.51 1.30 2.18 #5 fuel o i l original 12.3 13.2 1.29 0.92 1.51 2 days 12.5 13.7 1.32 0.93 1.67 1 week 12.5 14.0 1.13 0.97 1.37 7 weeks 13.5 15.0 1.00 0.96 1.64 3h months 13.5 14.6 1.24 0.94 1.53 Diesel fuel original 11.0 15.9 1.12 1.45 2.42 2 days 11.0 16.0 1.11 1.45 3.10 1 week 11.8 16.0 1.14 1.45 3.00 7 weeks 15.5 17.0 1.16 1.44 2.42 9 weeks 16.3 17.2 0.87 1.41 2.64 Discussion of the Controlled Weathering Experiment As already discussed, the experiment was designed to eliminate the weathering effects of d i s s o l u t i o n and biodegradation, and so to concentrate on the effects of photo-oxidation and evaporation. Each of these processes w i l l be discussed i n turn. Dissolution: I t i s not possible to state, from the experimental evidence, that d i s s o l u t i o n did not act on the o i l s i n the tanks, because the effects of evaporation and disso l u t i o n overlap, and can only be resolved by comparing components of d i f f e r i n g s o l u b i l i t y but s i m i l a r v o l a t i l i t y . This involves more detailed analyses which were not performed. However, because of the very high r a t i o of o i l to water that was used, and the very low solu-b i l i t i e s of hydrocarbons (see Table 8 ) i t i s assumed that d i s s o l u t i o n did not affect the composition of the o i l s . Biodegradation and photo-oxidation: No biodegradation of the petroleum was expected because of the lack of nutrients. The C-18/C-19 r a t i o confirmed this expectation, but also revealed what was not expected: that photo-oxidation also had no.affect. There was no change i n the C-18/C-19 r a t i o , nor any change i n the C-18/Env. r a t i o (other than 'noise') i n any of the three o i l s over the 3h months of the experiment, implying that neither biodegradation nor photo-oxidation of the o i l s occurred. The experiment indicates that photo-oxidation i s not effective as a weathering mechanism for o i l spread as a layer (3mm thick) under the radiative conditions i n B r i t i s h Columbia from October to January. Evaporation: The role of evaporation i s revealed most c l e a r l y by the 10% 50% parameters which measure the shape of the unresolved envelope: C^ ° and C^ °. A l l three o i l s show s i g n i f i c a n t increases i n these parameters. Crude o i l , i n p a r t i c u l a r , undergoes rapid i n i t i a l removal of the l i g h t e s t components, with a large portion of the evaporation occurring i n the f i r s t two days. This was 61 FIGURE 30 (copy): Effect of Evaporation on a Thin Film of Crude Oil A glass rod was dipped in Prudhoe Bay crude o i l , then placed i n a fume hood for 25 hours, with the following results: #1 Prudhoe Bay crude o i l #2 Thin film of Prudhoe Bay crude o i l exposed for 25 hours. also the period i n which the crude l o s t i t s pronounced odour. After about a month, the chromatograms indicate that s t a b i l i z a t i o n occurred, with v i r t u a l l y no loss of additional components over the next 2*5 months of exposure. No s i g n i f i c a n t change i n the C-17/C-18 r a t i o occured over the 3*2 months of expo-sure, implying that evaporation did not affect components b o i l i n g above 300°C. During the course of the experiment the crude o i l did not change i n general appearance, but i t became noticeably more viscous. No formation of tar lumps or sinking of the crude o i l occurred. The importance of the surface area i n determining the rate and extent of evaporation i s demonstrated by a comparison of Figure 10, which depicts crude undergoing evaporation i n a 3mm thick layer, and Figure 30 which shows evapora-tion from a thin f i l m . The following values are taken from these two Figures. O i l as 3mm layer O i l as a thin f i l m Time of Exposure 3h months 25 hours C." 10% 12.7 14.2 ,50% n 14.6 16.0 C-17/C-18 1.6 -» 1.5 1.4 •* 1.1 A l l three indices indicate that very much more evaporative weathering occurs i n 25 hours from a t h i n f i l m than occurs i n 3% months from a 3mm layer. The rate enhancement appears to be about 3 orders of magnitude, although i t i s not clear that evaporation would ever remove as much of the o i l from a layer as i t did i n 25 hours from a f i l m , since the layer appears to s t a b i l i z e after about a month. The intermediate f u e l o i l contained far less of the lower b o i l i n g components than crude o i l , and so was less effected by evaporation. Neither i t s appearance nor i t s v i s c o s i t y changed noticeably during the course of the experiment. Evaporation, as revealed by the gas chromatograms, was not evident i n the i n i t i a l week, and s t a b i l i z a t i o n occurred after 7 weeks, with no detectable 63 change occurring thereafter. Again, no evaporation was detected by the C-17/C-18 r a t i o throughout the experiment. the d i e s e l f u e l showed a markedly dif f e r e n t weathering pattern from 10% the other two o i l s . No s t a b i l i z a t i o n of the o i l occurred; instead, the C ' ' n 50% and C n ° values showed a steady r i s e with continued exposure. After 9 weeks the effect of evaporation had extended through almost the complete spectrum of alkanes, the C-17/C-18 r a t i o was 'feeling' the effect of evaporation, and the layer of d i e s e l o i l on the surface of the tank had been depleted to a thi n scum. A large amount of o i l was emulsified and dissolved i n the tank water, and the remainder had apparently evaporated. The very di f f e r e n t behavior of the d i e s e l from the other two o i l s i s not understood, but apparently i s a r e f l e c t i o n of the presence of emulsifying agents i n the d i e s e l f u e l , and the lack of high-boiling components to r e t a i n the lower-boiling fr a c t i o n s . Conclusions 1. Photo-oxidation i s not an e f f e c t i v e weathering mechanism for o i l i n a moderately thick layer. 2. The rate of evaporation from a layer of o i l i s very much dependent on the surface volume r a t i o , varying over at least 3 orders of magnitude from a thin f i l m to a 3 mm layer. I t appears that reduced surface area may r e s u l t i n less absolute l o s s , no matter how long the o i l i s exposed. 3. Evaporation has a l i m i t e d effect on heavier o i l s , reaching a point where s t a b i l i z a t i o n occurs and further evaporation i s n e g l i g i b l e , but t h i s s t a b i l i z a t i o n does not occur for l i g h t e r o i l such as d i e s e l f u e l . 4. Evaporation alone i s not s u f f i c i e n t to produce tar lumps and cause sinking of crude o i l . In a s i m i l a r experiment performed by Ohya et a l (1973) crude o i l formed tar lumps and sunk after 200 days of exposure i n a 64 tank. The d i f f e r e n c e was that continuous c i r c u l a t i o n was provided, so that s u f f i c i e n t nutrients f o r m i c r o b i a l growth were supplied. Apparently micro-b i a l degradation i s c r u c i a l f o r the formation of t a r lumps and eventual s i n k i n g of crude o i l . CHAPTER 5 65 PETROLEUM RESIDUES ON THE SURFACE OF THE PACIFIC AND ARCTIC OCEANS Introduction The first quantitative report of petroleum residues in the marine environment was the result of a study commissioned by the American Petroleum Institute in 1958 (Dennis, 1959). A year-long measurement was made of o i l coming ashore at three locations near Miami, Florida. Oil came ashore on 341 days out of 355, and i t appeared that the o i l was always present offshore, since east winds always brought i t in. ' The presence of pelagic petroleum residues was first reported by P.M. David in 1965, although he had casually observed them since 1954 in the Mediterranean Sea and in the Atlantic and Indian Oceans (Horn et al, 1970). In 1970, Horn et al published the first quantitative information on pelagic tar, giving the concentrations observed on a cruise in the Mediterranean and adjacent Atlantic. It was, however, Thor Heyerdahl on his 'Ra' expeditions in 1969 and 1970 who dramatically focussed public attention on marine pollution, and par-ticularly on the presence of tar in the Atlantic. Heyerdahl published a book, popular articles, two scientific papers (see Heyerdahl, 1971), and received widespread coverage of his voyages in the mass media. He persistently stressed the shocking, virtually continuous o i l pollution he had observed on his two journeys. A considerable amount of scientific work followed on the heels of Heyerdahl's observations. A chronological summary of the literature dealing with the distribution of tar in the marine environment is presented in Table 11. The concentrations reported in these papers are summarized in Table 13. Also, the chemical composition of tar has attracted attention in an effort to determine its source. The papers dealing with chemical composition are briefly reviewed in Table 12. A quick scan of the literature cited in the above tables shows the 66 heavy emphasis which the Western Atlantic and the Mediterranean have received. At the time this project was instigated, in 1972, there was no information available on petroleum pollution in the PacificOcean. This dearth of research presumably stemmed from the fact that tar pollution of recreational beaches was riot a problem in the Pacific, so that the impetus for investigation was not great. At the time of writing (Dec, 1975) there are three papers dealing with o i l pollution in the Pacific, a l l in Japanese. Two of these deal with the waters in the immediate vicinity of Japan, and the third presents a great deal of data on the Western Pacific (see Figure 18), but a l l of i t is of a qualita-tive nature. No chemical analyses nor source determinations of tar in the Pacific have been made. The research presented in this chapter addresses these problems. With respect to the Arctic Ocean, no information exists other than that reported here. TABLE 11: Tar in the Marine Environment: A Literature Summary 67 Author and Date Dennis, 1959 Dennis, 1959 Horn et al, 1970 Oren, 1970 Heyerdahl, 1971 Morris, 1971 Polekarpo et al, 1971 Anon, 1971 Wellman, 1973 Morris and Butler, 1973 Finnerty et al, 1973 Butler et al, 1973 Location Beaches in Miami, Florida U.S. Eastern seaboard beaches Mediterranean and adjacent Atlantic Israel and Levant Basin North Atlantic crossing (between 15° and 30° N.) Northwestern Atlantic near Canada Mediterranean Mediterranean North Atlantic crossing(40°-60°N) Northwestern Atlantic and Sargasso Sea North Atlantic, especially Sargasso Sea Observations Oil came ashore whenever there was an east wind on 341 days out of 355. Generally free of o i l except for shorelines in the vicinity of major harbours. Tar was present in 75% of 734 neuston tows. Associated biota: bacterial film, isopod Idotea  metallica, & Lepas barnacles. Hardness was measured. Age was estimated to be at least 2 months for some. Beach pollution was severe. Visible tar pollution on 40 of first 43 days on Ra 11 expedition. Tar cone, in 20 tows. Estimated total tar in Atlantic at 27,000 tons. Associated biota: blue-green algae, diatoms, isopods, (I.metal- lica) , crabs, shrimp, & Lepas barnacles. Size classification of tar. Patchiness. Beach pollution severe, especially in Italy. Tar in each of 18 tows. Time series near Bermuda and on Bermuda beaches. Standing stock in Atlantic estimated at 85,000 tons. Degradation probably takes years. Electron micrographs of bacteria growing on tar lumps. Reviewed information on Atlantic. History of beach tar pollution in Bermuda. 6 8 3 (Table 11: Tar in the Marine Environment: A Literature Summary, continued) Author and Date Location Observations Marumo & Kamada, Pacific near 1973(in Japanese) Japan Ohya et al, 1973 Pacific near (in Japanese) Japan First to report tar quantities in subsurface tows. Made series of tows at lm. depth intervals, to 8m. Most tar in top 4 m .Associ-ated biota: blue-green algae, stony corals, bryozoa, copepods, and Lepas barnacles. 389 neuston tows. Tar cone, cor-related with oceanographic condi-tions. Artificially weathered crude o i l : after 200 days tar lumps had formed, and 70% had sunk. Butler & Morris, 1974 Sargasso Sea Patchiness of tar: despite efforts to cancel out effects of Langmuir circulation, tar varied up to lOx between successive tows. Jeffrey et al, 1974 Dwivedi and Parulekar, 1974 Saner & Curtis, 1974 Gulf of Mexico and Caribbean Indian coastline Florida beaches Tar from 104 neuston tows. Analyses of beach, pelagic and abyssal tar. 57 of 59 beaches investigated were polluted with tar; cone, ranged up to 4.5 kg/rn^. 1 yr. study of tar coming ashore. McGowan et al, 1974 North Atlantic 214 neuston tows made at ocean weather stations B,C,D, and E. High variability, but concentra-tions were definitely higher to the south in the Sargasso Sea. Sherman et al, 1974 Gulf Stream 379 tows. Sleeter et al, 1974 N.E. Atlantic 14 tows. Observed occasional long windrows of tar. Sleeter et al, 1974 West Sargasso Sea. 15 tows. Wade & Quinn, 1975 Sargasso Sea Suggested h.c. in the water column and surface microlayer were par-ticles of weathered tar sized 0.3 ;um to 1.0 mm. 69 (Table 11: Tar in the Marine Environment: A Literature Summary, continued) Author and Date Location Observations Nasu et al, 1975 (in Japanese) Butler, 1975 Morris et al, 1975 Western Pacific & Indian Oceans Mediterranean Results of 3 yrs.(1971-73) of neuston tows for tuna fisheries re-search program. Not quantitative: tar given as not present, present, or abundant. General review of pelagic tar for Scientific American. 48 tows. Compared results with Horn et al(1970). Source: tanker traffic. Ehrhardt & Derenbach, 1975 -N.E. Atlantic Used high speed catamaran neuston net. Analyzed 49 samples by G.C. No correlation of comp. with location. Microbial degradation minimal. Evaporation minimal, apparently limited by diffusion rate from tar ball nucleus. Morris et al, 1976 Sleeter et al, 1976 Sargasso Sea Caribbean Observed tar specks in the water column. Estimated 4 times as much tar in the water column (0-100m) as at surface. 61 tows made. Beaches contamin-ated on windward shores. High pelagic tar. Canary current Equatorial Atlantic Low levels of pelagic tar. 70 TABLE 12: Chemical Analyses of Petroleum Residues: A Literature Summary Reference Observations Drunnock et al, 1968 Analyzed two English beach tar samples and one pelagic tar sample. Noted high wax content. Gas chromatograms had bimodal distribution of paraffins typical of crude o i l sludges from tankers. Also determined S, viscosity, and specific gravity. Adlard, 1972 Reviewed the analytical techniques which could be applied to analysing persistent hydrocarbon pollutants. Butler et al, 1973 Published large number of gas chromatograms of tar from the Sargasso Sea. Attaway, et al, 1973 Anomalously high iron cone, greater than 0.1%, in 67% of 35 tar samples from the western North Atlantic. Suggested this indicated an anthropogenic source. Jeffrey et al, 1974 Determined S, asphaltenes, and did gas chromatography of beach, pelagic, and abyssal tar from the South of Mexico and the Caribbean. Feldman and Cawlfield, 1974 Used neutron activation analysis to measure V, Mn, Na, and Co in tar for use in identifying the specific source o i l . McGowan et al, 1974 Water content of tar samples from the North Atlantic ranged from 0-51%, average 21%. Butler & Harris, 1975 Published normal paraffin profiles of tar from North Atlantic, and concluded i t was mainly residues of waxy, paraffinic crude o i l . Mommessin and Raia, 1.975 Used infrared, S content, & gas chromatography to cate-gorize tar from the western North Atlantic. 71 TABLE 13: Tar Concentrations Reported in the Literature All reported concentrations have come from the North Atlantic. They are listed here by geographical location beginning roughly in the central northern area, proceeding clockwise right around the North Atlantic, and concluding with the centre, the Sargasso Sea. Location Ocean Station B (56°N, 51°W) C (53°N, 35°W) D (44°N, 41°W) N.E. Atlantic Mediterranean Canary Current Equatorial Atlantic Concentration (mg/m2) 0.00 0.1 1.2 6. 37. 9.7 2.0 3.9 0.1 No.of tows Reference 50 50 50 14 41 48 9 ? 22 McGowan et al, 1974 McGowan et al, 1974 McGowan et al, 1974 Sleeter et al, 1974 Horn et al, 1970 Morris et al, 1975 Sleeter et al , 1976 Polekarpov etal,1971 Sleeter et al, 1976 Caribbean Gulf of Mexico N.Antilles & Bahamas N.C.-Florida Va. to Cape Cod Gulf Stream 0.7 1.4 1.2 4.4 0.8 0.5 2.2 20 61 84 86 80 157 16 Jeffrey et al, 1974 Sleeter et al, 1976 Jeffrey et al, 1974 Sherman et al, 1974 Sherman et' al, 1974 Sherman et al, 1974 Butler et al, 1973 Sargasso Sea Northern Sargasso Sea (35°N, 48°W) 9.4 16. 2.6 34 15 50 Butler et al, 1973 Sleeter et al, 1974 Sherman et al, 1974 D i s t r i b u t i o n of Petroleum Residues on the Surface of the P a c i f i c 72 The i n v e s t i g a t i o n began w i t h a t r a n s - P a c i f i c c r u i s e from Tokyo to V i c t o r i a , B.C., Canada, i n 1972. Surface tows were made at 37 s t a t i o n s along the c r u i s e t r a c k using a f l o a t i n g net w i t h dimensions of 80cm x 30.5cm mouth and a mesh s i z e of 150 um. The net was r i g g e d so t h a t i t would tow o f f to the s i d e of the ship through water undisturbed by the ship's wake. The research s h i p , CSS P a r i z e a u , l e f t Tokyo on 10 October, 1972, proceeded east along 35°N to near the C a l i f o r n i a coast, then turned n o r t h along 125°W to reach V i c t o r i a , B.C. on 2 November, 1972. . The c r u i s e t r a c k i s shown i n Figure 13. FIGURE 18: Transpac-72. Cr u i s e Track and the Surface C i r c u l a t i o n P a t t e r n i n the North P a c i f i c . c r u i s e t r a c k **— warm surface c u r r e n t s tanker route to Japan c o l d c u r r e n t s Tar was present i n t h i r t y of t h i r t y - t h r e e tows along 35°N as b l a c k or brownish b l a c k lumps up to 3cm i n diameter. I t s c o n c e n t r a t i o n was c o n s i s --2 t e n t l y higher i n the Western P a c i f i c w i t h a maximum of 14 mg m wet weight, -2 and an average of 3.8 mg m . The c o n c e n t r a t i o n i n the Eastern P a c i f i c was an order of magnitude lower on the average. No t a r was found on the f i n a l l e g of the c r u i s e up the coast of North America along 125°W. The tar distribution is shown in Figure 14 and summarized in Table 14. FIGURE 14: Distribution of Tar and Plastics Along 35°N in the Pacific Ocean tar distribution plastic distribution Tows covered an area of 1,800 ± 300 m2. 140 E 150 160 170 180 170 160 150 140 130 W Position along 35 N TABLE 14: Summary of the Results of Neuston Net Tows Along 35°N Latitude Material found in neuston net tows Northwest Pacific (West of 172.5°W) Northeast Pacific (East of 172.5°W) tar in a l l tows in 15 of 18 tows plastics in 9 of 15 tows in 13 of 18 tows average wet weight cone.of tar(mg/m2) 3.8 0.4 average cone. of plastics(mg/m2) 0.2 0.3 average wet weight cone.of organisms (mg/m2) 4.7 11.2 (No contaminants of any sort were present in the final 4 tows on the line north up 125°W.) 74 The tar aggregates were often colonized by a biological fouling community which included a bacterial film, blue-green algae, bryozoa. , goose, barnacles (Lepas sp), and the eggs of Halobates, the marine water strider. Crabs, mostly s t i l l in the megalops stage, and, more frequently, the isopod Ideotea metallica were present on the lumps. The amount of plastic in the tows was also recorded, and is indi-cated in Figure 14 and Table 14. Plastic was present in 21 of 33 tows along 35°N a_s small (1-3 mm diameter^ round, colourless pellets weighing 20-50 mg each. In contrast to tar, the maximum concentration of plastic was found in the -2 Eastern Pacific (3.5 mg m ). The maximum number of pieces observed was 62, -2 corresponding to 34,000 pieces km . Smaller plastic pieces did not support a fouling community, although the larger ones had similar organisms to tar lumps. ' * Some paper, elastic bands, and wood were found in the first few tows off Japan (up to 500 miles from Tokyo). None were found in the remaining 9,000 kilometer journey. The oceanographic data collected on the cruise provided some insight into the reasons for the tar distribution pattern shown in Figure 14. The surface layer (0-300m) temperatures are plotted in Figure 15, together with the locations of the tar peaks. The zones of apparent influx of colder sub-arctic water from the north are indicated by the letters. It appears that the tar is associated with the warmer subtropical water of the North Pacific current (the extension of the Kuroshio current). Where intrusions of colder, subarctic water occur, the tar concentrations decline, which suggests that subarctic water is not polluted by tar, and that, when i t mixes with the pol-luted water of the Kuroshio system, i t causes a drop in tar concentrations. More recent experience has shown that tar is very patchy, so that re-peated tows in the same area may give tar concentrations that vary over an FIGURE 15: Temperaturer-Distribution i n the Surface Layer Along 35°N 75 Position along 35°N The temperatures are i n °C. The zones of i n f l u x of colder subarct ic water (A, B, C, D) and the locat ions of the peak concentrations of tar are indica ted . order of magnitude. Therefore the de ta i led pattern of peaks i n Figure 14 may have l i t t l e meaning, and the co r re l a t ion wi th the cold water in t rus ions i n Figure 15 may be co inc iden ta l . However, further data, which i s presented below, has indicated that the basic premise i s correc t : the tar i s associated with the Kuroshio current system, and the subarct ic water i s e s s en t i a l l y free of contamination. The resul ts from the Transpac cruise pointed out that there was s ign i f i can t contamination of the P a c i f i c Ocean by petroleum, which had gone unnoticed amidst the p r o l i f e r a t i o n of information on the A t l a n t i c Ocean (Table 11). The decis ion was made to pursue the inves t iga t ion to determine the extent of the tar contamination of the P a c i f i c , i t s source and fa te . A second cruise was undertaken i n mid-summer, 1973, to perform another transect of the P a c i f i c . The c ru i se , which was a part of the research program of Dr. McGowan at Scripps I n s t i t u t i o n of Oceanography, was chosen be-cause the c ru i se . t rack passed through the centre of the P a c i f i c subt ropica l gyre. 76 In the North Atlantic, tar and Sargassum accumulate in the sub-tropical anticyclonic gyre (the Sargasso Sea) apparently because of the down-welling that occurs at its centre (Butler et al, 1973). In order to determine if.'the same concentrating effects occur in the corresponding oceanic feature of the Pacific, a second cruise, Tasaday-3, was undertaken in mid-summer, 1973. The Tasaday-3 cruise, which was a part of the research program of Dr. McGowan at Scripps Institution of Oceanography, crossed the Northwest Pacific along 28°N, (Honolulu to Tokyo) passing directly through the centre of the subtropical gyre in the North Pacific. The results of the cruise are summarized in Figure 16. FIGURE 16: Distribution of Tar Along 28°N in the Pacific Ocean POSITION ALONG 2 8 ° N Other than the anomaly at 177WE, i t is clear that the values are lower than were found on the more northerly transect (Figure 11). The averag value obtained along 28°N (west of 172.5°W) was 1.4 mg m \ which compared 2 o with the average of 3.8 mg m obtained along 35 N. As for the higher values at the westernmost stations in Figure 16, one is in the Kuroshio current, and the other is nearby, which indicates that i t is the Kuroshio current which is most contaminated with tar. Thus the concentrating effect observed in the Sargasso Sea is not observed in the Pacific. This can be attributed to the fact that the gyre effect is much weaker in the larger Pacific Ocean than in the Atlantic. Presumably this is also the explanation for the lack of a characteristic Sargassuro community in the Pacific. To further clarify the extent of contamination of the Pacific by petroleum residues, permission was obtained to look through the extensive col lection of neuston samples at the Scripps Institution of Oceanography (see acknowledgements). 1944 tows were examined, and any tar present was removed, weighed, and kept for analysis. Concentrations were obtained by dividing the wet weight of the tar by the area covered during the tow (obtained from the record of the ship's speed, the time towed, and the dimension of the net) 2 For the Scripps samples^ , tows covered an average area of roughly 2,000 m , and 2 ranged from 1,000 to 28,500 m . Mesh sizes varied from 150-505 jim. The info mation obtained from a l l these samples has been condensed into Figure 1 7 , which indicates the amount of tar by a letter symbol, and the number of tows made in that location by the sides of a box. Table 15 summarizes the informa tion from the various cruises, and indicates the average concentrations from the various regions. The f u l l record is on f i l e at the Ocean Chemistry Divi-sion, Ocean and Aquatic Sciences, D.O.E. On the basis of the information available, which includes cruises from 1967 to 1972, the South Pacific.contains virtually.no tar. When i t was FIGURE 17: Distribution of Tar in the Pacific Ocean LEGEND: A letter indicates the concentration of tar in a given location. The sides of the box around the letter indicate the number of tows which have been averaged to give that concentration. The meaning of the symbols is as follows: Concentration 0 T M H X zero trace, less than 0.1 mg/m" 2 medium, 0.1 to 1 mg/m 2 heavy, 1 to 5 mg/m extra-heavy, greater than 5 mg/m (Y T JT |T I f 3 Number of Tows trace, one tow trace, average of 2-4 tows trace, average of 5-9 tows trace, average of 10-20 tows trace, average of > 20 tows The table summarizes information from cruises made during the period 1967-1974 (see Table 15 for summary of cruises). 79 TABLE 15: Summary of Cruise Information and Average Tar Concentrations By Area in the Pacific NORTHEAST PACIFIC (North of Equator , east of 160 W) Identification Year 0 T M H X Total Tows Alaminos 14 1967 39 - - - 39 Oceanographer 1967 17 - - - - 17 Jordan 20 1967 72 37 1 110 Jordan 30 1967 86 20 - - - 106 Washington 45 1967 54 11 - - - 65 Rockaway 47 1967 64 - - 1 - 65 Argo 11 1967 45 8 2 - - 55 Jordan 12 1967 53 13 2 - - 68 Rockaway 13 1967 71 4 1 - - 76 Jordan 50 1967 95 14 - - - 109 Rockaway 77 1967 66 1 - - - 67 Jordan 60 1968 82 16 - - - 98 Washington 75 1968 55 - - 55 Jordan 76 1968 58 1 - - ' - 59 Townsend Cromwell 1970 5 - - - - "5 Aries 1 1970 4 - - - '4 Jordan 57 1970 18 - - - - 18 Jordan 65 1971 8 • - - - - 8 Jordan 65A 1971 8 1 - - 9 Jordan 60 1971 21 - - - - 21 Transpac-72 1972 7 6 4 1 - 18 CALC0FI . 1972 81 87 5 1 1 125 Tasaday 1 1973 - 5 4 1 - 10 SOTW-13 1973 - 18 8 2 - 28 Weathership 1973-74 28 4 1 - • - 33 TOTALS 1037 196 28 6 1 1268 PERCENTAGES 81.8% 15.5%. 2.2% 0.4% 0.1% AVERAGE 0.03 mg/m „ . —l 80 TABLE 15: (Continued) NORTHWEST PACIFIC KUROSHIO AREA (25°N to 40°N, 140°E to 160°W) Identification Year 0 T M H X Total Tows Transpac-72 1972 - 1 6 8 4 19 Tasaday 3 1973 • - i o 19 4 3 36 TOTALS - 11 25 12 7 55 PERCENTAGES 0% 20% 45% 22% 13% AVERAGE 2 .1 mg/rn^  REMAINDER Identification Year 0 T M H X Total Tows Antipode 1970 3 4 - - - 7 Hakuho Maru 1971 4 5 4 1 1 15 S'OTW 1972 - 2 - - - 2 TOTALS 7 11 4 1 1 24 PERCENTAGES 29% 46% 17% 4% 4% AVERAGE 2 0 . 4 mg/m 81 TABLE 15: (Continued) SOUTH PACIFIC Identification Year 0 T M H X Total Tows Argo 11 1967 13 - - - - 13 Jordan 12 1967 48 - - ' - - 48 Rockaway 13 1967 63 2 - - - 65 Jordan 30 1967 19 2 — - - 21 Washington 45 1967 24 1 - - - 25 Rockaway 47 1967 89 1 1 - - 91 Alaminos 14 1967 57 2 - r- - 59 Oceanographer 1967 32 - - - - 32 Jordan 20 1967 18 - - - - 18 Jordan 50 1967 10 1 - - - 11 Jordan 60 1968 13 1 - - 14 Jordan 76 1968 41 1 - - - 42 Washington 75 1968 69 1 - - - 70 Rockaway 77 1968 87 3 - - - ' 90 Piquero 1969 14 - - - 14 Townsend Cromwell 1970 13 - - - 13 Antipode 1970 4 - - - - 4 Aries 1 1970 32 - - - - . 32 Aries 3 1971 22 2 - • ' - - 24 Jordan 60 1971 3 - - - 3 Jordan 65 1971 28 - - - 28 S0TW-3:etc 1972 10 - - - - 10 Cato 2 1972 16 2 - - - 18 TOTALS 725 19 1 - ' - 745 PERCENTAGE 97.3% 2.6% 0.1% - -AVERAGE 0.0003 mj ! , 2 j/m found i n the preserved samples, the tar was present i n very minute quantities only (about 1 mg per sample) and may have been contamination from the research ship. In the Northeast P a c i f i c , obvious cases of polluted samples occur, mainly offshore between 25 and 40 N. The concentrations decline to the south (occasional traces of tar) and to the north (traces of tar i n 5 of 33 tows at ocean weather st a t i o n P: 50°N, 145°W). The area of heavy contamination i s i n the Northwest P a c i f i c , par-t i c u l a r l y between 25°and 40°N. A l l 55 tows i n th i s area (made during 1972-73) contained t a r , many containing more tar than b i o l o g i c a l material (maximum -2 catch: 50.5 g tar i n a 40 minute tow, or 16.3 mg m ). There i s i n s u f f i c i e n t data to c l e a r l y delineate the northern and southern l i m i t s of contamination, but the qu a l i t a t i v e information reported by Nasu and Ueyanagi (1974) (see Figure 18) indicates that the frequency of tar i n the Western P a c i f i c decreases markedly below 20°N, and i s hardly ever present i n tows south of 5°N. The area of heavy contamination corresponds to the area d i r e c t l y affected by the Kuroshio current and i t s extension, the North P a c i f i c current. Summary of Di s t r i b u t i o n of P a c i f i c Tar (from Table 15)  Area Number of Tows South P a c i f i c Northeast P a c i f i c Northwest P a c i f i c : Outside Kuroshio area ( 2 5 ° - 4 0 O N , 140°E-160°W) Kuroshio area Total Tows 745 1,268 24 55 2,092 Average Concentration 0.0003 0.03 0.4 2.1 83 FIGURE 18: Q u a l i t a t i v e I n f o r m a t i o n on Tar D i s t r i b u t i o n s i n the P a c i f i c and I n d i a n Oceans a) October, 1970, t o September, 1971. b) October, 1972, t o September, 1973. (From Nasu and Ueyanagi, 1974, p. 17 and 19) 84 Time Series Observations of Tar Concentrations at Ocean Weather Station 'P* A regular oceanographic program i s funded by the Canadian government on the weather-ships manning ocean weather station 'P' (50°N, 145°W) i n the Northeastern P a c i f i c . Beginning i n 1973> neuston tows were made a part of the weathership program i n order to investigate surface pollution i n the waters off the west coast of Canada, and to establish a baseline before tankers begin plying the route from Alaska down the coast. Since 1973 tows have been conducted on a recurring (but not regular) basis on the line out to the weather station, and on station (see Figure 19 for locations). Because of the large size of the weatherships, and the very high distance from the water at which one i s obliged to work, the conventional floating neuston net i s not very handy. Another net was used based on the design of Sameoto and Jaroszynski (1969)• This net rides up on adjustable fins, angles away from the ship automatically, and can be towed somewhat faster than the conventional floating neuston nets. Six of these nets were built out of aluminum and used for the weathership program. From the beginning of 1973 to September, 1975, 113 tows were performed. Of these, 31 contained tar, usually i n minute amounts, and 5 contained p l a s t i c . 2 The average concentration of tar was 0.04 mg/m , with a range from 0 to 1.9 mg/m . The results are summarized i n Table 16. There i s no evidence that any particular trend i s occurring with time. Further information on baseline levels of ta r i n the waters off the British Columbia coast was obtained from the Superintendent of the Pacific Rim National Park on the west coast of Vancouver Island (49°00'N, 125 45'W). The park has about 20 miles of sand beaches directly exposed to the open Pa c i f i c . In 1971 the Ocean Chemistry Division, Department of Environment, visited Long Beach at the park to investigate very large tar balls up to 40 cm i n diameter which had appeared on the beach. In October, 19731 a l e t t e r was TABLE 16: Summary of Weathership Time Series of Neuston Tows 85 Cruise Dates No.Tows # Tows c Tar Ave. Tar # Tows c Plastic 73-001 73-003 73-004 73-006 73-007 73-009 1973 Jan.-Feb. Mar.-Apr. May-June Aug.-Sep t. Nov. Dec.-Jan. 6 9 7 6 1 6 3 0 0 0 0 2 .03 0 0 0 0 0.2 1 0 0 0 0 0 74-002 74-005 74-007 74-008 1974 Feb.-Mar. May-June Aug.-Sept. Nov. 17 7 6 3 11 2 3 1 .09 .04 .01 .01 1 0 1 0 75-003 75-004 75-005 75-007 1975 Apr.-May May-June July Sept. TOTALS 10 18 13 4 113 Summary of Tows by Quantity: Quantity : (mg/m2) No. of tows: Zero 82 Trace « . D 26 2 7 0 0 31 Medium (.1-1) .001 .007 0 0 Heavy (1-5) 1 1 0 0 Extra 0 5 ) Average Tow Area: 800 m Average Concentration of Tar: 0.04 mg/m Range: 0 to 1.9 mg/m per tow 86 written to the Superdntendent of the park asking i f any further such incidences had occurred, and requesting that a log of o i l and tar contamination of the beach be maintained. The Superintendent replied that he was not aware of any problem of contamination, but that a log would be maintained. By June, 1974, only two incidents of o i l pollution had been reported, and no tar. A further letter to the Superintendent in July, 1975, failed to e l i c i t a response. The tentative conclusion which can be reached from this correspondence, and by casual examination of the beach by the author, i s that noticeable tar contam-ination is not occurring on a regular basis. Sporadic or low-level tar pollution may be occurring. The levels of tar and plastic contamination will continue to be monitored as tanker traffic begins to move down the coast from Alaska to 'determine i f changes occur. FIGURE 19- Location of Ocean Weather Station P and Oceanographic Stations on Line P • ' 150* 14C* 130* 120* Tar Distribution in Local Waters The inshore waters of British Columbia were not travelled by crude o i l tanker traffic in 1972. However, there is heavy urbanization and indus-trialization in the Strait of Georgia, three refineries in Burrard Inlet, and a great deal of commercial and pleasure boat traffic. In addition, large quantities of refined products are shipped by barge and small tankers. The lack of crude o i l tanker traffic, the presence of many other possible sources of petroleum contamination, and the impending tanker route from Alaska through these waters, made i t worthwhile to investigate the local waters for tar con-tamination. Neuston tows were made in the Straits of Juan de Fuca, the Strait of Georgia, and in Burrard Inlet directly past the refinery operations, during a three day cruise of the research vessel C.S.S. Vector, 28-30 November, 1972.Of 36 tows,32 contained no tar, and the remaining four had minute traces too small to qualify.The locations of the tows are indicated in Figure 20. The absence of tar in the neuston tows left open the possibility that tar was being quickly deposited on the extensive shorelines in this enclosed area, leaving the surface waters virtually uncontaminated. A study was there-fore commissioned by the Ocean Chemistry Division, Department of Environment, fo We Healdath Consultants to investigate the local beaches. Nine beaches on Vancouver Island were checked once by a transect down the beach, and twice by walking the beach, during June and July of 1973. The location of these beaches is indicated in Figure 20. No tar was found on the surveyed beaches, although incidental occurences of o i l pollution and very occasional tar pollution were observed by the contractor in other locations. Specifically, tar was noted on one occasion adhering to logs and on two occasions adhering to rocks in the Gulf Islands. The very low incidence of tar on the shorelines, and the lack of tar in the surface waters indicates that virtually no tar pollution of the inshore waters is occurring. 88 The s i g n i f i c a n c e of t h i s f i n d i n g i n r e l a t i o n to the i d e n t i f i c a t i o n of the source of the tar found i n the open P a c i f i c w i l l be discussed i n a l a t e r s e c t i o n . FIGURE 20 : Locations of Neuston Tows and Beach Surveys in Local British Columbia Waters • ; 89 Tar and P l a s t i c s l n the Beaufort Sea During the summer of 1974 and 1975 the Ocean Chemistry Di v i s i o n made two cruises to the Beaufort Sea i n the A r c t i c Ocean to perform environ-mental baseline studies. As a part of this program, neuston tows were made to investigate surface p o l l u t i o n : i n 1974, four one hour tows were made; i n 1975, 17 tows were made. The locations of the tows are shown i n Figure 21. No tar or p l a s t i c s were found i n the 1974 investigation. In 1975, a piece of stryafoam was found i n one tow, and very small black pieces 0.1 to 2mm i n diameter occurred i n 11 of the 17 tows. The number of p a r t i c l e s varied from about ten up to several hundred per sample. These black p a r t i c l e s con-sisted of seeds, ash, dark t e r r e s t i a l detritus such as fragments of bark, f l y i n g insects caught i n tows, and occasionally what appeared to be tar specks. However, the t a r - l i k e material would not dissolve i n carbon d i s u l f i d e , and so was probably t e r r e s t i a l d e t r i t u s from the Mackenzie River run-off, which i s a dominant oceanographic feature of the Beaufort Sea. Beaches i n the Beaufort Sea were also surveyed for tar and p l a s t i c pollutants i n 1974 under a contract from the Department of Environment (see acknowledgements). 26.4 km of beach were surveyed i n the locations indicated i n Figure 21. No tar contamination was found, but p l a s t i c s were a common contaminant. I r o n i c a l l y , most of the p l a s t i c was related to o i l exploration, such as surveying flagging and p l a s t i c containers used for explosives i n marine seismic work (Wong et a l , 1974). ( I t : should be noted that many of the A r c t i c beaches are composed of coarse-grained material, so i t i s impossible to see small p a r t i c l e s of tar.) 90 In conclusion, the Beaufort Sea is more severely contaminated with plastic than with tar. The plastic is found mainly on the beach, rather than in neuston tows and so must be rapidly blown ashore. Tar may be present as very minute particles in surface tows, but the concentration is definitely 2 less than 0.001 mg/m and may be zero. Tar has not been observed on the beaches. FIGURE 21: L o c a t i o n of Neuston Tows and Beach Surveys i n the Beaufort Sea 15 e , . , 13 Unnumbered dots i n d i c a t e tows made d u r i n g the summer of 1974. Numbered tows tows were made i n 1975. Cross-hatching i n d i c a t e s beaches surveyed d u r i n g 1974. 91 V a r i a b i l i t y of Tar Concentrations Spatial Variations: The v a r i a t i o n that i s obtained i n tar concentrations when re p l i c a t e neuston tows are made i s very large. Table 17 shows the results of r e p l i c a t e tows made on the Tasaday-3 cruise. The concentrations vary over as much as an order of magnitude, a res u l t which has been observed i n other locations (Butler and Morris, 1974). These variations are not random i n nature. This i s demon-strated by the data from the Tasaday-3 cruise which i s plotted as a histogram i n Figure 22a. I f we assume that the Western P a c i f i c along 28°N i s randomly contaminated with t a r , then the frequency d i s t r i b u t i o n of concentrations should follow a Poisson distribution.curve. I t i s clear from Figure 22a that the Pois-son d i s t r i b u t i o n and the observed d i s t r i b u t i o n d i f f e r markedly, p a r t i c u l a r l y i n the f i r s t frequency class, and i n fact the goodness of f i t i s unacceptable 2 ( pQ(_ ) .005). The discrepancy i n the f i r s t frequency class indicates that the tar concentrations are clumped rather than being randomly di s t r i b u t e d (Archibald, 1948). The d i s t r i b u t i o n may follow Neymann's contagious d i s t r i b u t i o n , more closely. Neymann's d i s t r i b u t i o n assumes that i f one i n d i v i d u a l (a tar lump i n this case) i s present this increases the p r o b a b i l i t y of other individuals being present (Neymann, 1939). Neymann was dealing with larvae hatching from clumps of eggs and gradually spreading out from the location of the eggs. He assumed that the egg clumps were randomly d i s t r i b u t e d , and that the number of eggs per clump was a random variable. The analogy i s that the egg clumps are patches of tar lumps l e f t behind by tankers cleaning the i r tanks (see section on sources of t a r ) . The surface turbulence then distributes the tar i n a manner s i m i l a r to the movements of larvae away from egg clumps. Unfortunately there i s i n s u f f i -cient data to ascertain the two parameters required to calculate the Neymann d i s t r i b u t i o n : the mean number of patches per unit area; and the mean concentration per patch. 92 TABLE 17: Variability of Tar Concentrations in Replicate Tows Location Area of Tow (m ) Tar Concentration (mg/m2) Variation Factor /highest concA \lowest cone. / 28°N, 160°E 4800 6800 3100 8100 5600 3600 4000 6700 5800 3400 0.81 0.93 0.26 0.22 0.18 0.81 0.38 0.49 0.48 0.73 5.2 28°N, 170°W 1900 3300 0.01 0.01 1.0 28°N, 175°W 1600 2300 0.26 0.48 1.8 28°N, 170°E 1600 2300 0.07 0.10 1.4 28°N, L46°E 3600 3700 0.17 0.41 2.4 30°N, 143°E 3100 3600 16.3 1.3 12.5 34°N, 140°E 1900 2200 5.6 1.3 4.3 (Data are from the Tasaday-3 cruise.) 93 FIGURE 22 : Histograms of Tar Concentrations from the Western Pacific along 28 N a) Histogram of Tar Concentrations and the Poisson Distribution TAR CONCENTRATION (mg/m2) b) Histogram of the Log of Tar Concentrations and the Normal Distribution 8 6 2 0 LOG TAR CONCENTRATION 94 Langmuir c i r c u l a t i o n may also affect the d i s t r i b u t i o n and patchiness of tar. I t w i l l tend to regroup tar into windrows spaced from 10 to 50 m apart. Butler and Morris (1974) eliminated t h i s effect by making tows i n a c i r c l e of about 1 km diameter, but tar concentrations i n rep l i c a t e tows s t i l l varied over an order of magnitude. This indicates that Langmuir c i r c u l a t i o n i s not the prime factor influencing the patchiness of ta r . Polekarpov et a l (1971), work-ing i n the Northeast A t l a n t i c and using a s t a t i s t i c a l method which i s not cle a r l y described i n the translation of their paper, estimated that tar was d i s -2 tributed i n patches of about 200 to 3000 m area. The combined evidence suggests that Neymann's model of dispersal from random point sources may be appropriate. Those who have considered the d i s t r i b u t i o n of tar i n the l i t e r a t u r e have concluded that the d i s t r i b u t i o n i s close to log normal (Morris, 1971; Polekarpov, 1971; Morris et a l , 1975). This route i s simpler mathematically than attempting to deal with Neymann's d i s t r i b u t i o n , but reveals less of the nature of the processes occurring. I t i s useful primarily for establishing the confidence l i m i t s of mean concentrations, and for determining i f d i f f e r e n t oceanic areas have s t a t i s t i c a l l y d i f f e r e n t concentrations of ta r . For example, Figure 22b displays the data from 22a as frequency classes of the log of tar concentration. The d i s t r i b u t i o n i s approximately log normal, and has a geometric 2 2 mean of 0.25 mg/m with 66% confidence l i m i t s of .05 to 1.15 mg/m . The a r i t h -2 o metic mean i s 1.2 mg/m . Further north i n the Western P a c i f i c along 35 N 2 (Transpac-72 cr u i s e ) , the arithmetic mean concentration of tar i s 4.6 mg/m , 2 and the geometric mean i s 2.9 mg/m with 66% confidence l i m i t s of 1.0 to 8.5 2 mg/m . Thus the mean concentration i s s i g n i f i c a n t l y higher (66% confidence level) along 35°N than along 28°N. The geometric mean provides a measure of central tendancy. I t s uncer-tainty can be decreased by increasing either the length or the number of neuston tows. The arithmetic mean i s not a s t a t i s t i c of a log normal d i s t r i b u t i o n and P° 95 confidence limits cannot be calculated directly from the variance. Neverthe-less the arithmetic mean is the appropriate statistic for estimates of absolute abundance, and so i t is used throughout this chapter. Temporal Variations: The variation of tar concentrations with time at the same location has been investigated by Butler and Morris (1974) using time series data from station S (32°10'N, 64°30'W) in the Sargasso Sea. Spectral analysis indicated a cycle of 10 weeks duration which they attributed to an unknown feature of ocean circulation. The time series data from station P presented in a previous section is too irregular for application of spectral analysis. No cycle of any significance is apparent from a perusal of the data. 9 6 Size Distribution of Pelagic Tar Particles Tar particles ranged in size from a few tenths of a millimeter in diameter up to five centimeters (34 g). The spectrum was presumably curtailed on the small end by the mesh of the neuston nets, which varied between 150 and 505 um depending on the cruise. The tar obtained on the Transpac-72 cruise was size classed, and the following distribution was found (150 um mesh net): Largest Dimension No. of Particles (mm) <1 237 1-5 442 5-10 345 >W 106 Most particles were in the 1-5 mm range, and most of the mass in the 5-10 mm range. The size distribution was apparently consistent across the Pacific with no significant tendency for smaller particles to occur either in the east or the west. Polekarpov et al (1971), working in the central Atlantic, found a sim-ilar size distribution of particles (most particles in 4-8 mm size range), al -though larger pieces were more common in that location than in the Pacific. They explained the size distribution by postulating that tiny particles of tar 'snow-ball' to form larger pieces until a dynamic equilibrium is reached (in the 4-8 mm range) where the disruptive forces of wave action equal the cohesive forces of the tar pieces. This explanation is not very satisfactory because tar does not conglomerate in the laboratory purely by colliding. Morris et al (1976) found tiny particles of tar in the water column, and theorized that tar lumps eventually disintegrate under the weathering process to produce very fine particles. If such a process were occurring in the Pacific, small particles would be expected to be more common in the eastern regions remote from the main source (see section on sources), and i n the Western P a c i f i c near the source tar pieces should be fresher and l a r g e r . No such pattern of s i z e d i s t r i b u t i o n i s evident i n the data. The theory presented here i s that t a r neither d i s i n t e g r a t e s nor snow b a l l s , but i s produced at the source i n roughly the same s i z e d i s t r i b u t i o n as i t i s found i n the ocean, and i s removed by sinki n g i n a manner which i s not si z e s e l e c t i v e (see section on p h y s i c a l fate of t a r ) . 98 Chemical Analysis of Tar Determination of Water Content: Nine tar samples from the Transpac-72 cruise were dried by placing each tar sample in an evacuated chamber together with molecular sieves for several days. The molecular sieves trapped water vapour, but not volatile hydrocarbons because of size exclusion. In this manner i t was possible to dry the tar without removing any volatile hydrocarbons. Analysis by Gas Chromatography: The tar samples (0.2-0.5g) were dissolved by vigorous shaking in 5ml of carbon disulfide, centrifuged, and stored in glass vials with teflon sep-tums in a refrigerator. The samples underwent two different gas chromatographic analyses. 84 samples were run on a Dexsil column. Dexsil 300 is a non-polar, high-temperature packing which can be programmed up to 400°C with very l i t t l e bleed. This gave a 'fu l l ' chromatogram of the o i l on a stable baseline. Secondly, some of the samples were run on a polar FFAP column to separate isoprenoid peaks (pristane and phytane) from the corresponding paraf-fin peaks (C-17 and C-18). FFAP is not very temperature-stable, so that the chromatograph could only be programmed up to 250°C, giving a 'partial' chromatogram. The detailed instrumental parameters used in the analyses are given in Table 18. 99 TABLE 18: Instrumental Parameters for Gas Chromatographic Analyses Full (high-temperature) chromatograms: A Varian Aerograph 1400 gas chromatograph was used. The working parameters were as follows: Sample size: 5 to 40 ,,1 Carrier gas: N,, Column: length 10' by 1/8" diameter 3% Dexsil 300 on 100/120 mesh Chromosorb W (acid-washed) ml/min: Carrier 20 H 2 50 Air 350 " Inj. port: 300°C Detector: 400°C Column Conditions: Programmed Initial temp: 70°C> for two minutes Final temp: 400°C> hold Program rate: 8°/min Chart speed: 0.5 IPM Detector: FID Sensitivity: variable within 10 ^  range Chromatograms for isoprenoid/paraffin ratios: The same parameters were used except for the column and the temperature programming: Column: length 10' x 1/8" diameter 12.5% FFAP on 80/100 mesh Chromosorb G (acid-washed, DMCS treated) Column Conditions: programmed Initial temp: 100°C for 2 minutes Final temp: 250°C Analysis by Flame Atomic Absorption Spectophotometry: • 104 tar samples were analysed for their iron and nickel content using flame atomic absorption spectrophotometry. 0.2 to 0.5g of tar were digested in a mixture of 75% HNO^  and 25% HCIO^  for approximately 2 hrs. at 150°c using teflon-lined digestion bombs. The dissolved metals were then made up to 50 ml in 4N HN03> and the solution was analysed for Fe and Ni on a Jarrell-Ash model 810 atomic absorption spectrophotometer. 100 Results of Chemical Analysis Water Content: For the nine tar samples dried by the use of molecular sieves, water was found to represent an average of 22% of the weight of the tar, and varied from 13% to 29%. Gas Chromatograms: The 84 f u l l chromatograms are presented in Figure 23. The most important parameters from these chromatograms are summarized in Table 19. The partial chromatograms for isoprenoid/paraffin ratios are pre-sented in the discussion. Iron and Nickel Content: The results of the analysis by atomic absorption spectrophotometry are listed in Table 20. 101 FIGURE 23: Chromatograms of Pelagic Tar Chromatograms of 84 pelagic tar samples are presented on the following pages. They are organized by cruise, and within the cruise, i n chronological order by the date on which the neuston tow was made. The chromatograms are numbered for reference purposes, and next to the number i s a line of information about the sample. The information i s l i s t e d as follows: cruise; tow identification; location of tow; date of tow; method of storage of sample; date of analysis; chromatogram run number. Below this line of information i s a description of the sample i f one was noted when the sample was prepared. The dashed lines indicate the baseline. The instrumental parameters used to obtain the chromatograms are given i n Table 18. The chromatograms are summarized i n Table 19. 102 Transpac-72; Tow 1; 35N, 140E; 10/10/72; frozen; 8/4/74. (several fresh lumps) Transpac-72; Tow 2; 35N, 141E; 10/10/72; frozen; 18/8/75; 178. (middle, mostly interior, section of largest lump, partly encrusted) 40 Transpac-72; Tow 3; 35N, 142E; 10/10/72; frozen; 18/8/75; 179. (inside of largest lump, partly encrusted with bryozoa) 1 0 3 4. Transpac-72; Tow 4; 35N, 143E; 10/10/72; frozen; 20/8/75; 194. (half of medium lump, appears fresh) lA/J 25 30 I-35 40 45 5. Transpac-72; Tow 5; 35N, 145E; 11/10/72; frozen; 20/8/75; 195. (one lump) 17 18 25 20 30 1-1-35 — - 4.5 40 VJ 6. Transpac-72; Tow 6; 35N, 150E; 12/10/72; frozen; 20/8/75; 196. (one lump from a large sample) 104 7. Transpac-72; Tow 7; 35N, 155E; 13/10/72; frozen; 20/8/75; 197. (piece of a compacted mass) 8. Transpac-72; Tow 8; 35N, 160E; 14/10/72; frozen; 20/8/75; 198. (one wet lump) 45 9. Transpac-72; Tow 9; 35N, 165E; 15/10/72; frozen; ?/3/74. - • 1 : i 1 : ' 1 ' ' - • l - l - r 4 --4 - _L _L:L 4„ 4- - : i 1 ' 14 --_ 4-4 - _j_L 4_ - - i - A \ 0 t 1 : | - - r i - - - - -- -!•- - - - - ; - -f-- - ; - \Jr : - -i- j : - - r i - 4~ -\ '; 4 - - - - -_ 4- • -4\-: - | - - | - | - 3 0 t 1 •-14--— r 7 —WT'-.— - „ ; _ - - --!-- ; 8 : 2 \4iy_ - - i I •hi- -._ -...L 15 j AA -----i 7 : 2 5 - - - -• ' j- 4 - 4- - 4 r -- - -- -4-4- - - -- _.u -- - - : -rttn-h r r i r 1; i | | | 7 -iv ! i - j- F T 105 10. Tranpac-72; Tow 9; 35N, 165E; 15/10/72; frozen; 11/7/75; 60. (outside section of a large brown ball) •. • • i l ! f | " T ! i ; T " ; I"' T 1 ! . . i 1 i i i i ! T T — • ' i i ! , *~ l i ! \ i - - ! • - ^ j " • ; i : 1 i • ; L i i 1 • •: i ' i , i P l . : ' i : T " i . | i i : , 'j : — t . . j _ . . : L L J i I : 1 ' • ; i : . . . : ~ T J i T " f T l - T7" ~ ' ~ Jl -u l T r . . T ! i i. :-^L.^L I J i _ ! ' • ' ' ! 1: . ! ! M i • : i : • •. •. : • i : ! i i i !!:!!•'.-•; i i ! 1 , • i • i i ':': : •: • 1 I;I 1 i • ; ! ! U , ' ' i • : ! '• ; ; • i • i V l t - T ; : ; ! ' : ' ; ' • ! : i i r i r r : ' ; j * ! ' 1 j • 4-0 1 ; * ! i ! • : : ' i ; : : : ( i : ' i i , - p i t •:,: 0' « • i i ! ; ! : ! ' ~'f i r i - h ^ - t r '» J j . ; | : i : :"! ;! i ! : i • i ! -j i = 7 - - ^ . M i l i ~ H 1 i.r Vrr - 4 — - - 1 i 1 .! i ! j i 11. T r a n s p a c - 7 2 ; Tow 10; 35N, 170E; 16/10/72;. f r o z e n ; 7/2/74. ( f i r s t sample) 12. Transpac-72; Tow 10; 35N, 170E; 16/10/72; frozen; 20/2/74. (second sample) 106 13. Transpac-72; Tow 10; 35N, 170E; 16/10/72; frozen; 10/7/75; 56. (outside section of large black lump, no growth except small barnacles) 14. Transpac-72; Tow 11; 35N, 175E; 17/10/72; frozen; 5/3/74. (twelve lumps, lots of growth) 15. Transpac-72; Tow 12; 35N, 180; 18/10/72; frozen; 1/7/75; 64. (one black lump) I 2.5 j '15 20; W ...L._..L....k:,i: 107 16. Transpac-72; Tow 13; 35N, 178W; 18/10/72; frozen; 6/3/74. (first sample, ten lumps with l i t t l e growth) - : - "T~~ ' ... .. . ....... - - • -. 4 - . ; ...... Jl !._ -. •-• --i 30 1 7 .-• _.T_ — -- 18 0 - -T 4 - : - -- -• -- -- -1 -i I 35 - _L_ ... -- - -• - - - : - 4 - ----- -15 1 1 ... t J J 1 In pr r A, l i 41 ) - - - - ; - -- - J II - - j - -• - :-• - •-:- : 1 17. Transpac-72; Tow 13; 35N, 178W; 18/10/72; frozen; 9/4/74. (second sample, numerous tiny lumps) 30 18. Transpac-72; Tow 13; 35N, 178W; 18/10/72; frozen; 10/7/75; 57. (third sample, end section of large brown lump) 108 19. Transpac-72; Tow 14; 35N, 175W; 19/10/72; frozen; 18/8/75; 177. (one lump, heavily encrusted, appears old) 20. Transpac-72; Tow 24; 35N, 148W; 24/10/72; frozen; 29/3/74. (encr. lumps) 21. Transpac-72; Tow 26; 35N, 142W; 25/10/72; frozen; 21/8/75; 200. (one dry lump) 22. Transpac-72; Tow 28; 35N, 138W; 26/10/72; frozen;21/8/75; 201. (two partly encrusted lumps) 23. TSDY 3; Tow 1; 28N, 163W; 22/7/73; frozen; 16/8/75; 161. 109 25 17 15 -18 20 v. l/w IN 3Q 35 40 24. TSDY 3; Tow 2; 28n, 165W; 22/7/73; frozen; 15/8/75; 158. ..25.. 17 18 20 JJ/u 30 WW -35,.. 25. TSDY 3; Tow 3; 28N, 168W; 23/7/73; frozen; 15/8/75; 159. 125. 18 " 20 IN IM 30 110 26. TSDY 3; Tow 10; 28N, 178E; 28/7/73; frozen; 28/2/74. (outside scraping of a large (34g) lump) i 1 i : i s 1 ! • 1 i • _ _ L 44- -44 - hi- : 7 : t : _.:..: - 4-4- -f4~ - H ~ - ! - _~ i .... 4-- i — - - - 4 - h i - i - ' , ----- .20 4 — - -. 3C - - 4 ^r"i..—-- i 15 •-: r - i - -:—' . --' - . .:. .. - 4- 4 - : ; - ! - • - . .;. - • - - - -4 - i -j- --j -4- -;- -• - 4 - h r ! {• --35 - 4 - 4 "ip-h : it fit to " 10 XX 4- - i so 4! \ A WXi — — . XT* u -r-r - :~ -•-'[- „: ! 4 - ; : . ' . : ... .. . . .Li . . - i - i__ 27. TSDY 3; Tow 10; 28N, 178E; 28/7/73; frozen; 19/8/75; 187. (outside of same lump) =35--17 I 28. TSDY 3; Tow 10; 28N, 178E; 28/7/73; frozen; 19/8/75; 185. (inside of lump) --, 17 -. £p-r I l l 29. TSDY 3; Tow 10; 28N, 178E; 28/7/73; frozen; 27/2/74. (five lumps, no growth) k k - ™ ~ j - • - „:....:.._ 4-: - j 4- 5 i ••!- -ki- _ ! _ ! _ .-pp. 4~k - .... -- r •• • — — • 7—!-. - - - ... — -rk . „:. 44 — 'II 20 i — | — 4 — -— •• :k~ .... .... :- - - - -- — . . . -:- r -k i 44 ~ r 4 -|-r- • — — — - .._ - • — 4 - ; \- - -:4 ' - - i - -- r i - -;-k 4- - -r- H 4 - 4 - i l 4- - -4k 4 rk - - ! - -4 - 44-i s ; _L. r - 4- - - :l 1 4- - - - - c-M b 4~k . 11 1 h In w W ta LJ IA AAJ 44 J 4-j- -r r — r - -31. TSDY 3; Tow 12; 28N, 175E; 28/7/73; frozen; 27/2/74. (1/3 of largest lump, bacterial covering) 112 32. TSDY 3; Tow 12; 28N, 175E; 28/7/73; frozen; 21/8/75; 203. 33. TSDY 3; Tow 13; 28N, 172E; 29/7/73; frozen; 21/8/75; 204. (four very small lumps, one h a l f encrusted with bryozoan) 25 30 35 40 4.5(\ A> „ 50 34. TSDY 3; Tow 17; 28N, 165E; 31/7/73; frozen; 21/8/75; 205. (two pieces, appear fresh) 113 35. TSDY 3; Tow 18; 28N, 160E; 1/8/73; frozen; 21/8/75; 206. (one wet lump) 17 18 15 30 U l 25 I N u U 35 40 36. TSDY 3; Tow 19; 28N, 160E; 1/8/73; frozen; 28/3/74.(several.fresh'lumps) 35 17 18 20 25 30 40 37. TSDY 3; Tow 23; 28N, 160E; 1/8/73; frozen; 21/8/75; 207. (one lump, no growth, appears fresh) 35 40 45 50 114 38. TSDY 3; Tow 25; 28N, 160E; 1/8/73; frozen; 21/8/75; 208. (a piece of compacted tar) 39. TSDY 3; Tow 26; 28N, 160E; 1/8/73; frozen; 16/8/75; 164. 40. TSDY 3; Tow 28; 28N, 155E; 3/8/73; frozen; 22/8/75; 210. (two pieces, no growth) 115 42. TSDY 3; Tow 33; 28N, 146E; 5/8/73; frozen; 22/8/75; 212. (piece of l a r g e s t lump, b a c t e r i a l covering, otherwise no growth) . TSDY 3; Tow 34; 31N, 143E; 5/8/73; frozen; 28/3/74. (second sample) S fi... 6 - B . . . . . . . . . . f i 45. TSDY 3; Tow 34; 31N, 143E; 5/8/73; frozen; 21/2/74. (third sample) 46. TSDY 3; Tow 35; 31N, 143E; 5/8/73; frozen; 25/8/75; 249 (three pieces, fresh-looking, no growth) 25 u _ UUWU 30 35 40 117 47. TSDY 3; Tow 36; 34N, 140E; 6/8/73; frozen; 27/3/74. (one lump, fresh) i ' 25 48. TSDY 3; Tow 37; 34N, 140E; 6/8/73; frozen; 10/7/75; 57. - • - . . i 118 49. Weathership 73-001?; Stn P; 14/1/73; frozen; 8/7/75; 48. (l/8th inch diam. ball) .:. !--;:. | .1.-1.:. I -r_ - i " — (—-•—' :— =j—J=|H|Hlr= = zz =|= = =\= = = i f = } j S I J j | = i H -;-7r Ivjvi ^ !"-U-;!-;;-" --"! -•: "-j iii i j — j = i i -. •- 4 i f j i i j i i [ . i i j i i i zz —: -|= ir. =g .1— r r rE ii'jiij'ii'|'iii!ii ;r. I"? i — l~z\iirii i f —{4—:—) —!— =!== o 4 f f i f - - —: H i ™ _m =j-. ~ iii .= rii i i t i i l i i f i i i . i d i i i i - i i i i i i f i i i i i 4 ;-.-i=i=i=ii-l~isi?! ii; i i r f i ' j S S j i i l l ~z ~ i— iz: ii.- iii i i ~ i i i lzi i i i i 4 f - - " H r f - f i f - f - ••IT i f iiiii i.n i.ii! -i - i - -r J : | ; ': : i ' ; • rr 1 :i:. - i r i i i i 3 £ i i . i i - i i — i i 4 f i f i =jrrj='fr =j ir : = =. z. T.I-sS^i - i^ j— f — i -f i f IH I ! 4 4 -ii."ull : f ip • "ii f i i j i 1 ; - ! : ; - i : } i i i". i .: : • : i .. ! " ;! i 5i i'-i '• '• i:.; S p S S =!=•——!=!=• n \\\zz\z^\zAzz —i.iiiiiH- - - z i i i p - ~ i : -• : : i *7i:~-: -i . & : i^:iii^ ; 4 ^ : i i i i i i 4 V : 4 f = — ! = j = i ^ i E : ! = f i f 4 4 - i 4 f = i = J S ~ rr.: ~ ii: i i i i i i - iiiiii. i - r i i i i l i i .1 .- : 4 |4ii:ii EE: "iii iii:i-:ir Ez ii-rr:: . : : - . 4 4 - 4 :k!~ 1 .• v'i -]=; - f - f i i i i =!=;=!=!= i = ~ ; i i i iiii zz -: : ;: - ;-1 1 ! iiiiiiiiiii iii iiiiii iiiiii iii 4 •- e|=j H;i^ '3=is;=::!= HJril=: = = : — :. - 4 f 4 1 4 4 1 iii ~ i 4 - i f 4 f f 4 f i s i i f i f f i f 4 f 4 i ; 3 4 =: j ^ 1 j — j : ~ | - - (—! i^ j — : . . . i • : . 1 4 f f ii: -i - - : • Jt . f f i i s k f i — ^ i i i H ! i 4 f f = ! = f f = 111!:=:}—:.— :zz: ~z: n •—r.:z.T i ^ i i i 4 iiiiii ii.!4iiii4iii i i i i i b - i i f i i p E S E i j i i j i i i 4 i = j f i ^ i |= i -iB, =iii=l—j— = ii:ii.iii:ii:-i:!."--: P _w: ^  T!=M- = f i f i S i i i = ! H ! 4 : i = ! H 4 ! i i ^ - r — : — »=rn^i=-Ja-!—i -•)—*— --' -f-i—i—IT r 1 I i t f t 1 • = i ~ | : = j f i f !— 50. Weathership 73-009; Stn 4; 8/12/73; frozen; 6/3/74. (very fresh oil) i i . i . 1 ;: -r.-j i i " 1 i : f: : ° k- ! i : : -i-- - - - - -- - 4 - - 4 4 - -_ _ — — -18 , . : — — - - - S -' — — - — - 4-i- — — - 4 - - 4 - •4-r- - - - - -- - i - i - H - - ; -h - - - - 4 4 4 - 4 - H -70 i i i ; t - • i - -4-iiiiii- . : . T: "•!" = i i I - ft" i - f -r-- - .1 I i 2 5| i —: ' i -~ 3 0 ~ - 4 4 4-- 4 4 - / i — -'— ' : 1 5 \ .{ 1 ri VJU IL L. . =• t J L - : ----- ;i : 1 ----. , 1 : . . .• r. . 1 i i - 1'":' : 51. Weathership 74-00.2; Stn 12 out; 18/2/74; frozen; 11/8/75; 139. 35 119 52. Weathership 74-002; Stn 9; 17/2/74; frozen; 10/4/74. (first sample, a l l of tar similar in appearance, five lumps, no growth) 53. Weathership 74-002; Stn 9; 17/2/74; frozen; 25/8/75; 245. (second sample) 35 40 45 . 54. Weathership 74-007; Stn 11 out; 4/8/74; frozen; 12/8/75; 142. 17 18 20 25 1/w u 120 .55. Weathership 74-007; Stn P; 12/8/74; frozen; 13/8/75; 149. 1.8 56. Weathership 74-007; StnP; 23/8/74; frozen; 13/8/75; 150. 57. Weathership 74-007; Stn P; W M ; frozen; 12/8/75; 146 35 30 18 / 17 25 U U u 40 . 45 121 58. Weathership 74-007; Stn 4; 17/9/74; frozen; 13/8/75; 151. 35 59. Weathership; Bowie Seamount; 53N, 136W; 19/11/74; frozen; 13/8/75; 154. 122 60. TSDY 1; A1NR16; 28N, 155W; 18/6/73; formalin; 24/8/75; 238, (first sample - one encrusted lump) 25 2 0 17 15 18 u 30 U 35 40 61. TSDY 1; Al NR16; 28N, 155W; 18/6/73; formalin; 24/8/75; 181. (second sample - one black lump) 35 17 15 18 20 25 30 \45 62. TSDY 1; A2 NR28; 28N, 155W; 20/6/73; formalin; 28/3/74. (one piece from a loose conglomerate) 25 17 15 4 W 18 20 v 30 35 40 45 123 63. TSDY 1; A3 NR41; 28N, 155W; 22/6/73; formalin; 9/8/75; 183. 64. TSDY 1; A4 53; 28N, 155W; 24/6/73; formalin; 25/8/75; 243. 124 65. TSDY 1; A5 63; 28N, 155W; 26/6/73; formalin; 23/8/75; 219. (first sample - one piece, barren and sticky) 66. TSDY 1; A5 63; 28N, 155W; 26/6/73; formalin; 23/8/75; 221. (second sample - one piece 75% ecrusted) 2& 67. TSDY 1; A6 75; 28N, 155W; 28/6/73; formalin; 22/8/75; 216. • (largest lump in sample, 75% encrusted) 125 68. SOTW 13; Stn A2; 28N, 155W; 30/1/73; formalin; 24/8/75; 239. (first sample - half of encrusted lump) 30 69. SOTW 13; Stn A2; 28N, 155W; 30/1/73; formalin; 23/8/75; 224. (second sample - non-encrusted lump) 35 ' i n , 40 18 17 15 20 30 25 I IN H5 i I: 70. SOTW 13, Stn A2; 28N, 155W; 30/1/73; formalin; 23/8/75; 225, (third sample - part of large lump) 126 71. SOTW 13; Stn A2, tow 14; 28N, 155W; 31/1/73; formalin; 18/8/75; 173. (one medium lump) 3.5 . 72. SOTW 13; A3; 28N, 155W; 31/1/73; formalin; 25/8/75; 250. 35 73. SOTW 13; A3-20; 28N, 155W; 1/2/73; formalin; 18/8/75; 175. (one lump, not encrusted) 127 74. SOTW 13; Stn 4; 28N, 155W; 1/2/73; formalin; 18/8/75; 174. (one lump, not encrusted) 35 I7 18 15 20 30 25 40 75. SOTW 13; 5 tow 61; 28N, 155W; 6/2/73; formalin; 23/8/75, 227. (ten small pieces) 25 17 18 20 I 15 u u u u u 30 3 5 45 40 4 & ' 76. SOTW 13; Stn 18, tow 103; 31N, 137W; 16/2/73; formalin; 24/8/75; 236. (many small pieces, a l l with bacterial covering) 25 17 18 15 20 30 35 40 45 128 77. SOTW 13; Stn 22, tow 106(?); 32N, 124W; 19/2/73; form.; 23/8/75; 229. (three pieces with small amount encrusting) 78. SOTW 13; Stn 24, tow 106; 32N, 124W; 19/2/73; form.; 23/8/75; 226. (several small pieces, no growth) I 129 79. CALCOFI 7210; 39-145; 39N, 145W; 20/10/72; formalin; 20/8/75; 193. (first sample - half of a very brown, encrusted lump which sank in fresh water) 80. CALCOFI 7210; 39-145; 39N, 145W; 20/10/72; formalin; 25/8/75; 240 (second sample - a brown lump with bacterial covering) 81. CALCOFI 7210; 39-145; 39N, 145W; 20/10/72; formalin, 24/8/75; 235. (third sample - a black lump with no apparent bacterial covering) 35 40 130 •82? CALCOFI 7210; 30-80; 42N, 129W; 7/10/72; formalin; 11/7/75; 65. (a black ball, no growth) 35 83. CALCOFI 7210; incomplete identification; formalin; 29/3/74. (two lumps, l i t t l e growth) 84. Rockaway; 47-507; 7N, 95W; 20/9/67; formalin; 2/4/74. (one lump with bacterial covering) 131 TABLE 19: Summary of Chromatograms of P e l a g i c Tar This t a b l e summarizes key parameters of the chromatograms presented i n F i gure 23. The i n f o r m a t i o n i s l i s t e d i n mine columns which f o l l o w t h i s format: Column 1: #. Gives the number of the chromatogram i n F i g u r e 23 t h a t i s being summarized. Brackets i n d i c a t e samples from the same tow, and a s t e r i s k s i n d i c a t e samples from the same t a r lump. Column 2; ' D e s c r i p t i o n ' . Summarizes the d e s c r i p t i o n of the sample which was noted at the time of sample p r e p a r a t i o n . The f o l l o w i n g terms are used -: f r e s h : no growth o r b a c t e r i a l c o v e r i n g , s o f t , and s t i c k y b l a c k : no growth o r b a c t e r i a l c o v e r i n g , but hard brown: covered w i t h a t h i c k b a c t e r i a l l a y e r no g r . : no growth. May or may not have b a c t e r i a l c o v e r i n g , but not encrusted or otherwise overgrown p. encr.: p a r t i a l l y encrusted w i t h bryozoa encr.: completely encrusted w i t h bryozoa i n s . : i n s i d e of t a r lump outs.: outside s c r a p i n g o f a t a r lump f r a g . : fragment taken i n d i s c r i m i n a t e l y from a l a r g e r mass h a l f ; one; two; e t c . : the number of lumps used t o make up the sample Column 3: C-17/C-13. The height of the C-17 peak d i v i d e d by the h e i g h t of the C-18 peak. A r a t i o s u b s t a n t i a l l y l e s s than one i s an i n d i c a t i o n of evaporation. Column 4: C-18/C-19. A l a r g e r a t i o of these peak h e i g h t s (above 2.0) i n d i c a t e s t h a t biodegradation i s o c c u r r i n g . Column 5: ^ f i r s t * ^ e :i'^rs't' c l e a r l y i d e n t i f i a b l e peak i n the chromatogram. Column 6: C m a x » The highest p a r a f f i n peak measuring from the envelope up. Column 7? C e n (^. The l a s t c l e a r l y i d e n t i f i a b l e p a r a f f i n peak. Column 8: 'Lo c a t i o n ' . The p o s i t i o n of the neuston tow from which the sample was obtained. A bracket i n d i c a t e s samples are from the same tow. Column 9: 'Comment'. Used t o i n d i c a t e samples t h a t may be from n a t u r a l seeps, a n a l y s i s dates of samples from the same lump, and i f the sample s i n k s i n f r e s h water. 132 TABLE 1?: continued # Description Transpac-72 C-17 C-18 C-18 C-19 '"'first ^max 'end Location Comment (35° N) 1. several, fresh 1.18 2.5 15 38 46 140"E 2. i n s . , p. encr. .74 0 0 17 38 47 141° E 3 . i n s . , p. encr. .57 17 37 43 142°E 4. h a l f , fresh 1.04 1.6 13 36 48 143° E 5. one 1.06 1.5 16 29 50 145°E 6. one 1.67 4. 17 29 50 150°E 7. fragment 1.08 2.2 17 33 51 155°E 8. one .86 7. 17 44 53 160C'E 9. .45 1.6 17 38 n ) 165°E 10. outside 1.13 ' 1.3 15 17 44 J 11. 1.50 . 1 . 3 16 27 47/) 12. 1.39 1.1 14 17 170" E 13. outs., black 1.26 1.2 15 37 48 J 14. twelve,'encr. 1.29 6. 17 17 51 175° E 15. one, black 1.15 .96 14 27 41 180* 16. ten, p. encr. 1.30 1.1 14 27 41 7 17. numerous 1.21 1.1 14 17 36 178°W 18. end, brown 1.0 6. 17 42 53 j 19. one, encr. .86 5.8 17 18 47 175°W 20. several, encr. 1.31 1.1 15 27 51 148° W 21. one 1.11 4.3 13 37 47 142°W 22. two, p. encr. .75 1.0 15 33 49 138° W 133 TABLE 19: continued # Description Tasaday-3 C-17 C-18 •C-18 C-19 C„. . G f i r s t max end Location Comment ( 28°N ) 23. 1.13 1.0 15 27 42 163"W 24. 1.33 1.1 16 27 38 165*W 25. 1.30 1.1 16 27 38 l68"w *26. outside 1.32 1.1 12 .. 27 49 *27. *28. outside inside 1.29 1.27 1.1 1.1 12 . 12 27 27 45 45 > 178°E 29. f i v e , no gr. 1.33 1.0 12 27 48 J 1 30. two, no gr. 1.33 2.0 17 27 35 175 "E 31. l / 3 , brown 1.32 1.2 15 32 50 | 175"E 32. .83 10. 17 44 . 50 . 33. four, p. encr. 1.0 1.6 17 27 48 172"E 34. two, fresh .89 2.3 17 34 . 50 165"E 35. one .95 1.3 15 34 48 l60°E 36. several, fresh 1.05 1.3 15 37 49 II 37. one, fresh .71 2.6 17 37 49 tl 38. fragment .98 1.4 15 42 49 II 39. .95 2.3 16 37 ^ II 40. two, no gr. i n . i n . 35 39 49 155°E 41. 1.62 C O 17 36 44 148°E 42. frag., brown .64 0 0 17 36 46 146°E 43. two 1.42 1.2 13 17 35 > 1 .44. 1.06 1.0 15 27 47 > 31N,143E 45. 1.00 3. 17 37 49 j 46. three, fresh 1.07 1.1 16 27 40 11 n 47. one, fresh .91 0.9 17 27 43 34N,140E 48. 1.59 1.4 17 27 36 ti it an. 2/74 an. 8/75 an. 8/75 an. 2/74 seep? 134 TABLE 19: continued # Descr ip t ion C-17 C-18 C-18 C-19 Weathership 49. one . 6 5 2.7 5 0 . v . fresh 1 . 3 7 1.5 51. 1 . 0 0 5. 52. f i v e , no g r . 1 . 0 9 2 . 0 53. . 7 5 3 . 2 54. 1 . 4 6 2.4 55. - . 6 0 CO 5 6 . . 4 3 57. . 5 0 CO 5 8 . 1 . 1 4 1 . 8 5 9 . . 9 6 1.5 Tasaday-1 6 0 . one, encr. 1 . 0 4 1 . 0 6 1 . one, black 1 . 1 7 1 . 2 6 2 . fragment 1 . 2 6 1 . 1 6 3 . 1 . 1 1 1.4 6 4 . . 5 7 6 5 . one, fresh 1 . 1 7 1 . 2 66, one, p . encr. 1 . 3 2 1 . 1 6 7 . one, p . encr. 1 . 2 2 1 . 1 Southtow-13 68. ha l f , encr. 1 . 0 2 0 . 9 5 6 9 . one, no g r . . 9 6 1.4 7 0 . fragment . 9 1 1.6 7 1 . one 1 . 0 9 L 5 7 2 . . 9 0 1.4 7 3 . one, no g r . 1 . 0 7 1.4 7 4 . one, no g r . 1 . 0 6 1.4 7 5 . ten . 9 5 1 . 0 7 6 . many, brown 1 . 0 0 1.3 77. three, p . encr. 1.08 1 . 0 7 8 . some, no g r . 1 . 1 9 1 . 1 ! f i r s t C max l a s t Locat ion Comment 17 26 3 2 Stn P seep? ! 5 17 3 1 Stn 4 seep? 17 3 2 3 8 Stn 12 13 1 7 3 1 3 2 4 6 } 4 8 J f Stn 9 16 1 7 3 8 Stn 1 1 1 8 3 7 4 6 Stn P subsur. 18 3 7 4 2 tt subsur. 17 3 7 4 5 it subsur. 14 3 5 4 6 , Stn 4 16 18 3 4 53N,136W seep? 15 15 27 3 6 4 0 1 4 4 J . 28N,155W 1 4 27 4 5 it ti 14 1 7 27 II it seep? 17 3 8 4 8 tt II 15 15 4 0 27 50 ] 4 5 J 28N,155W 15 3 1 4 5 it tt 15 27 3 5 I ) 14 3 5 49 / > 28N,155W 15 3 8 4 8 J 14 3 5 4 5 n ti 15 3 6 4 8 it II 14 3 6 4 5 ti ti 14 3 4 4 0 II tt 16 27 4 5 tt ti 15 27 4 5 31N,137W 15 26 3 5 32N.124W seep? 15 17. 4 7 tt ti seep? 135 TABLE 19: continued # Description C-17 C-18 C-18 C-19 C f i r s t C max 0 J end Location CALCOFI 7210 79. h a l f , encr. 1.11 1.7 14 35 47 1 80. one, brown •95 1-5 15 38 45 | • 39N,145W 81. one, black .94 2 .2 15 38 47 J 82. one, black 1.08 1.3 1 3 . 35 48 42N,129W 8 3 . two, p. encr. 1.25 1.2 13 36 52 ? Rockaway 47-507 8 4 . one, brown .42 0 . 8 17 22 35 7N,95W Comment. sank 136 TABLE 20: Iron and Nickel Content of Tar Samples Note: When more than one sample has been analyzed from the same tow, the results are listed consecutively. SAMPLE IRON CONC. (ppt) NICKEL CONC. (ppt) Natural seep 0.2 0.1 0.30 0 0 0.09 Prudhoe Bay crude 0 0.01 .14 0 Aries 9 Queer 2.3 0 Aries 9 Quit 2.1 0 TSDY 1 Al NR 16 1.4 3.1 0 0 TSDY 1 A2 #30 6.9 0 TSDY 1 A3 8.2 0 TSDY 1 A3 #43 12.0 0 TSDY 1 A4 53 1.3 0.5 0 0 TSDY 1 A5 #63 0.6 32.6 0 0 TSDY 1 A5 NR 28 1.3 6.0 0 . 0 TSDY 1 A6 NR 73 6.9 0 TSDY 1 A6 #75 0.8 0.3 0 0 TSDY 1 A3 NR 41 0.8 0.9 •17 0 CALCOFI 7210 39.145 1.1 0.5 0 o CALCOFI 7210 31.145 13.1 0 CALCOFI 27.141 0.1 2.6 0 0 CALCOFI 35.133 1.5 0.4 0 0 CALCOFI 31.137 0.5 0.4 0 0 SOTW 13 Stn 22, 106 1.3 0 SOTW 13 #88 7.0 0 SOTW 13 #89 2.1 0 SOTW 13 Dipnet 0 0 0 .06 SOTW 13 Stn 22, 105 0.7 1.1 0 0 SOTW 13, 7, #83 0.5 0 ARGO 11 11-044 0.8 0 137 TABLE 20: (Continued) SAMPLE IRON CONC. (ppt) NICKEL CONC. (ppt) TASADAY 3 -Tow 2 1.2 0 -Tow 3 0 .9 0 -Tow 5 12 .6 0 -Tow 7 4 .6 0 .01 -Tow 10 7.1 0.6 6 .3 0 0 0 -Tow 11 2.7 0.1 -Tow 12 3.5 0 -Tow 14 10 .4 0 .01 -Tow 15 13 .5 0 -Tow 17 1.8 2.3 0 0 -Tow 18 0 0 .5 o 0 -Tow 19 13.6 4 .1 0 0 -Tow 20 9.4 0 -Tow 21 5.4 0 .01 -Tow 22 8.6 0 .02 -Tow 23 7.0 18 .6 0 0 -Tow 24 5.6 0 .01 -Tow 25 2.9 0 .01 -Tow 26 8.0 0 -Tow 27 4 . 2 0 -Tow 28 4 . 0 0 -Tow 29 27.6 1.3 -Tow 30 5.7 0 -Tow 31 5.3 3.7 0 0 -Tow 32 5.8 0 .01 -Tow 33 13 . 0 13 .5 0 0 -Tow 34 13.9 0 -Tow 35 0 .2 2.4 0 0 -Tow 36 7.1 0 -Tow 37 1-4 0 138 TABLE 20: (Continued) SAMPLE IRON CONC. (ppt) NICKEL CONC. (ppt) Transpac 1 15.8 0 3 49.4 o 4 3 7.5 n 0.3 5 4 0.4 n 0 6 13 27 5 n n 0 7 37.9 0 8 9.8 1-7 n 0 9 4.9 0 10 4 2.2 n 0 11 3.2 0 12 2 15.0 n 0 13 6 0 n 0 14 11.5 0.03 16 5.7 0 17 4.4 0 18 0.6 0 23 10 3.3 n 0 25 23.2 0 26 6 2.3 n n = not determined 139 Discussion of Chemical Analyses  Water Content: The water content of the nine tar samples is considerably less than the typical percentage of water in a fresh water-in-oil emulsion, which is about 80% (Berridge et al, 1968). However, the average value of 22% agrees well with the amount found by McGowan et al (1974) of 21% (range 0-51%) in tar samples from the Atlantic. Gas Chromatograms; Residue. The tar would not completely dissolve in carbon disulfide. The residue in six samples averaged 15% of the weight of the tar, and ranged from 5 to 24%. Residues were obviously organic in nature, and were similar in appearance to the original tar. They seemed to be composed of high molecular weight asphaltic compounds. Reproducibility of Chromatograms. The reproducibility of chromatograms from day to day, with different operators, and with different Dexsil columns was excellent. Although the attenu-ation varied, the pattern of peaks was always clearly reproduced. An example is shown in Figure 24 . A second and more impressive example is to be found in chromatograms 26 and 27 (Figure 23 ) of different samples from the same lump. The analyses were performed by different operators one and a half years apart on different Dexsil columns. The chromatograms are identical as nearly as the eye can see. The general observation over fifty-odd duplicate runs was that the reproducibility was excellent over the carbon number range of about C-12 to C-40; below and above this range the relative peak heights sometimes changed. The 140 FIGURE 2.4: Reproducibility of Chromatograms CALCOFI 7210; 39-L45; 39N, 145W; 20/10/72; formalin; 25/8/75. a) Run #241 25 17 18 2 0 u u b) Run #248 17 18 Two chromatograms of the same sample run on the same day with the same instrument. Six other samples were analyzed between the two runs. Note the excellent reproducibility of the pattern and relative heights of the peaks. 141 position of peaks eluting from the column near the very beginning of the pro-gram (before C-12) also was variable, apparently because of the instability of the thermal regime of the gas chromatograph in this region. However, this was not a problem with tar lumps, which seldom contained paraffins less than C-12 in carbon number. Limitations of the Method. It should be understood that the method has two distinct limitations. It is limited at high carbon numbers because of the upper limit to which the chromatograph can be programmed, and because the high molecular weight com-pounds have a limited solubility in the solvent, carbon disulphide. Secondly, the column provides only low resolution. All the aromatics, cyclo-paraffins, and heterocycles appear as a broad envelope onto which the paraffins are added. The resolution is not sufficient to distinguish the isoprenoids from the paraf-fins, so that pristane and phytane appear lumped in the same peaks with C-17 and C-18 respectively. Despite these limitations the chromatograms do provide a great deal of information on the tar samples, particularly on their paraffin content. Storage of Samples. Tar samples were stored by refrigeration and in formalin. Both appeared to be entirely satisfactory. Chromatograms 26 and 27 (Figure 23) show that refrig-erated tar does not change detectably over a year and a half of storage. Simi-larly there is no indication of any systematic change occurring in the samples stored in formalin. Contamination of samples by trace hydrocarbons in the formalin, although a potential problem in trace tissue analysis, does not affect the analysis of the tar because of the great excess of tar hydrocarbons. 142 Characterization of Tar Chromatograms. From the information revealed in the gas chromatograms five parameters have been chosen as being especially informative. These parameters have been listed in Table 19. They are: the C-17/C-18 ratio; C-. , the carbon number first of the first clearly identifiable peak; C x> the largest paraffin peak; and ^end ' t* i e ^ a s t clearly identifiable peak. A description of the sample and the location of the neuston tow are also listed. Other authors have used other parameters to characterize chromatograms. For instance, Blumer, Erhardt, and Jones (1973) characterized repeated chroma-tograms of stranded crude o i l with six ratios as well as the carbon numbers at which the envelope reached 10% and 50% of its maximum value. The parameters used here were chosen to reveal the weathering of the o i l by biodegradation (C-18/C019), and by evaporation (C-17/C-18 and c f i r s t ) > a n d t o distinguish natural seeps from tanker residues (C and C ,). In general the envelope r max end ° shape was not found to be useful in making these distinctions. The mean values of the five parameters for various subclasses of tar samples are listed in Table 21 . C-17/C-18: The average ratio for the 82 tar lump samples was 1.05 ± .27, which compares with the average found by Martin et al (1963) for seven-teen crude oils of 1.25. Although the difference is not statistically signifi-cant, the lower ratio in the tar samples may reflect the preferential loss of the lower boiling heptadecane and pristane by evaporation. Some support for this interpretation comes from the correlation between the C-17/C-18 ratio and spe-cific subclasses of tar. The subclasses listed in Table 21 that consist of older tar have lower C-17/C-18 ratios, suggesting that the removal of the C-17 peak occurs with prolonged exposure. Specifically the ratio is lower for Cf^rst = 17 than for C^ . =15, and for C = 36-38 than for C =27. Similarly, tar first max max which is extensively degraded by bacteria (C-18/C-19 = «>.) has a low ratio. TABLE 21 : Average Composition of Subclasses of P e l a g i c Tar D e s c r i p t i o n of Subclass .No. of Samples C-17 C-18 C-18 C-19 C f i r s t C max C . end L o c a t i o n (long.) Average of a l l t a r 82 1.05 + .27 2.9 15.7 +2.6 31 ±7 44 +6 170° W +32 .. C f i r s t " 1 5 25 1.10 + .16 1«3. 15 31 ±7 45 +5 164° W +29 C f i r s t - = 1 7 25 0.92 ±•35 5.1 17 33 ±7 46 +6 174°E +33 C = 27 max 21 1.18 + .17 1.2 15.2 +1.4 27 43 ±5 177°W +25 C = 36-38 max 24 0.90 + .30 4.6 15.8 +1.5 37.0 47 +2 173°E +32 C-18 = 0 3 C-19 8 0.71 + .38 oo 17.3 + .5 37.0 + .8 45 +2 178°E ±37 N a t u r a l seeps 10 1.08 + .33 1.3 15.0 +1.3 19 35 ±5 142°W +28 Weathership (without seeps) 8 0.87 + .36 5.6 16.3 +1.8 32 ±7 44 ±4 140°W ±6 Western P a c i f i c (west of 172*E) 29 1.06 + .31 3.3 16.6 +3.8 32 ±7 39 ±9 153°E +11 f r e s h , black 14 1.07 + .17 1.6 15.1 +1.3 33 +6 45 ±5 178°E ±34 brown, p. encr., encr. 20 : 1.01 + .27 3.2 15.6 +1.3 30 +7 45 +6 170°W ±34 s m a l l p i e c e s ,(< o . i g) 14 1.15 + .13 1.7 14.9 +1.4 27 +6 45 ±5 l a r g e pieces (> 0.5 g) 15 1.02 + .23 3.4 15.2 +1.6 34 ±7 47 +4 FIGURE 25 : P r i s t a n e and Phytane i n P e l a g i c Tar 144 a) TSDY 3, Tow 10; 28N, 178E; 28/7/73; f o r m a l i n ; 1/8/75; 127. (Compare w i t h chromatograms 26, 27, and 28 i n F i g u r e 23) 115 1 8 - 2 , 0 17 . 1 "BI" -Ms— b) TSDY 3, Tow 19; 28N, 160E; 1/8/73; f o r m a l i n ; 7/8/75; 131. (Compare w i t h chromatogram 36, F i g u r e 23) c) Weathership 74-002; 50N, 143W; 18/2/74; f r o z e n ; 8/8/75; 135. (Compare w i t h chromatogram 51i Figu r e 23) 145 C-18/C-19: This ratio (henceforth termed the biodegradation index) is a measure of the extent to which microbial action has degraded the tar sample. The C-18 peak reflects both the amount of octadecane and the amount of phytane, whereas the C-19 peak reflects only the amount of nonadecane. Since the paraf-fins are more easily degraded than the isoprenoids(see Chapter 2), the C-19 peak may be reduced to zero by microbial action, while for the C-18 peak only the octadecane is removed and the phytane remains. Thus a high value of the biode-gradation index is an indication that microbial degradation is occurring. The partial chromatograms in Figure 25 illustrate this effect by separating the iso-prenoids from the paraffins. Chromatogram (a) shows fresh tar in which the par-affins have not been degraded, and chromatogram (c) shows a tar sample which has undergone extensive microbial degradation leaving only the isoprenoids. The average value of the biodegradation index for seventeen crude oils was 1.5 (cal-culated from data in Martin et al, 1963)^ , whereas for the tar samples the aver-age value was 2.9. Of the 82 tar samples, 33% had values greater than 2, indi-cating that microbial degradation is an important factor in the degradation of tar at sea. C... : The frequency of occurrence of the carbon numbers of the first n J first identifiable peaks are shown in Figure 26 . The first peak varies from dodecane (C-12) to C-35. The two most common paraffins forming the first peak were pentadecane (C-15) and heptadecane (C-17). These two i n i t i a l peaks distin-guish two-quite different subclasses of tar samples: C-15 indicates a 'younger', less degraded sample; C-17 an older, degraded sample. C : The carbon numbers of the largest peaks are also shown in max Figure 26 . They vary from hexadecane (C-16) to C-45. Most commonly C-27 is the largest peak, particularly in tar samples with l i t t l e microbial degradation while C-36 to C-38 occur as the largest peaks in chromatograms of extensively degraded tar. * see Appendix A. 146 C e n d : T h e c a r b o n numbers of the l a s t c l e a r l y i n d e n t i f i a b l e peaks are a l s o shown In Figure 26. They range between C-27 and C-54, with an average of C-44. The upper l i m i t i s probably imposed by the a n a l y t i c a l method as already discussed. FIGURE 26: Carbon Numbers of F i r s t , Maximum, and Last P a r a f f i n Peaks from Eighty-Two (82) Chromatograms of Pelagic Tar V] - • - a — C . . . f i rst 7 ''max • — © • c e n d 1 * 1 1 1 1. 1 f " . i ' 1 ' T ^ l\ 1 - B r r - * \ . i T \ J-W • 15 , ' r . V c / \ I \ Q \ 1 \ 1 I / \ f \ 1 \ 1 O / , °\ ; / \ / ' > / ,1 Q , CD . © JK f ^ ' $ ' l\ / ® -fco'x » » ^ — ^ ^ , n r T V V \ . . ^ _ 40 45 50 55 C A R B O N NUMBER 147 Metal Analyses of Tar Of the 104 tar samples analysed for iron, 77% had concentrations of iron greater than 1 part per thousand in wet weight of tar. In contrast, crude oils have less than 0.1 ppt (International Petroleum Encyclopedia, 1974). The concentration of Ni in 94 of the 104 samples was also determined to indicate i f general metal enrichment was occurring in the tar by scavenging of metals from the sea water or by concentration of the metals in the original o i l during the weathering process. In 90 of 94 samples the nickel was below the detection limit of 0.01 ppt, and in the other four samples the highest amount obtained was 0.17 ppt. Ni concentrations in crude o i l are in the range of 1 to 100 ppm (International Petroleum Encyclopedia, 1974; Brunnock, 1968). These consistently low values for Ni indicate that general metal enrichment was not occurring. TABLE 22: Summary of Fe Concentrations in Pelagic Tar Fe Concentrations (wt. Fe/wet wt.tar) > 10 ppt 1-10 ppt <1 ppt No. of samples 21 59 24 % of samples 20% 57% 23% 148 Source of Pelagic Tar In Chapter 1 the sources of petroleum to the marine environment were reviewed. The three major sources from which tar residues could originate are tanker t r a f f i c , natural seepage, and land run-off. Run-off from land sources i s least l i k e l y to result i n tar formation since there i s no obvious mechanism by which formation of tar can occur from the dissolved or s l i c k contamination c h a r a c t e r i s t i c of land sources. Local tows made i n Vancouver harbour near a heavily i n d u s t r i a l i z e d area with three r e f i n e r -ies contained no tar (Figure 20 ) and tows off the heavily populated Los Angeles area of C a l i f o r n i a (Figure 17 ) also gave low values, evidencing that land sources do not lead to tar formation. The remaining l i k e l y sources are tanker t r a f f i c and natural seepage. The major tanker lane i n the P a c i f i c i s the massive Middle-East to Japan route (Figure 27 - 5,570 thousand barrels or 758,000 metric tons per day i n 1972). The area of heavy tar contamination i n the P a c i f i c (shaded i n Figure 17 ) can be ex-plained by assuming tar wastes are discharged by tankers south of Japan, become entrained i n the Kuroshio current (Figure 28 ) and create a plume of contamination which extends downstream across the P a c i f i c . The decreasing quantities of tar found to the east can be attributed to the gradual dispersal, degradation, and eventual sinking of the tar. The absence of tar from the South P a c i f i c and the A r c t i c correspond with the absence of crude o i l tanker t r a f f i c i n these areas. Natural seepage, on the other hand, i s of the same order of magnitude i n the North and South Paci-f i c (see Figure 4) and also occurs i n the A r c t i c , so the tar d i s t r i b u t i o n does not correlate with the areas of natural seepage. The gas chromatographic analyses provide a second i n d i c a t i o n that tanker t r a f f i c and not natural seepage i s responsible for the pelagic tar contamination i n the P a c i f i c . Of the 82 tar samples analysed, 72 contained long-chain, waxy FIGURE 27: Tanker Routes i n the P a c i f i c Ocean i n 1972 149 Numbers i n d i c a t e the q u a n t i t i e s of crude o i l t r a n s p o r t e d i n thousands of b a r r e l s b a r r e l s per day ( l b a r r e l = 0.137 m e t r i c t o n s ) . (Rearranged from I n t e r n a t i o n a l Petroleum En c y c l o p e d i a , 1973) FIGURE 28: Surface C i r c u l a t i o n i n the North P a c i f i c Ocean Continuous arrows i n d i c a t e the tanker route t o Japan. S o l i d l i n e s i n d i c a t e warm surface c u r r e n t s . Dashed l i n e s i n d i c a t e c o l d surface c u r r e n t s . 150 paraffins (higher carbon number than C-25) in much greater abundance than they are normally found in crude o i l . This high wax content is typical of tanker residues. The precipitate or sludge remaining in the tanks of crude o i l carriers after unloading normally has an enriched wax content of 20-30% above that of the crude cargo (Holdsworth, 1970), the amount of wax coming out of solution depending on the wax content of the crude and the length and temperature condi-tions of the loaded voyage. Typically the residues amount to about 0.4% of the cargo carried (Holdsworth, 1970), and they are discharged overboard during the deballasting and tank-washing procedures on tankers that do not employ the load-on-top (LOT) technique. The waxy sludge has a great propensity to form a tight water-in-oil emulsion under the action of the washing jets and subsequent pumping, and so is ideal for the formation of pelagic tar lumps. Figure 29 illustrates the evidence provided by. the chromatograms that tanker residues are the major source of pelagic tar. The first chromato-gram is of Prudhoe Bay crude o i l . Like most other crudes, i t has l i t t l e paraf-fin content above C-25. The second chromatogram shows the same crude o i l after it has been exposed for 25 hours. Note that the paraffins up to C-15 have eva-porated, but above C-17 the spectrum is unchanged. The third chromatogram is of a sample that apparently came from a natural seep (the sample was dip-netted near Santa Barbara, an area of extensive natural seepage). The trace is very similar to that of evaporated crude o i l , except that microbial degradation has removed most of the paraffins, leaving only the isoprenoids at C-17 and C-18. No long-chain paraffins are evident. The fourth chromatogram is of a typical tar lump, and shows an abundance of long-chain paraffins. The contrast at high carbon numbers with both the crude and the natural seep o i l is very clear. Of the 82 tar samples analysed, 12% looked akin to chromatogram #3 and may have come from natural seeps, while 88% were comparable to chromatogram #4 and presumably originated from tanker residues. Thus the presence of long-chain, waxy paraffins 151 FIGURE 29: Comparison of Chromatograms of Crude O i l , Weathered Crude, Natural Seep O i l , and Pelagic Tar  #1 Prudhoe Bay crude #2 Prudhoe Bay crude exposed f o r 25 hr. #3 Weathered Natural Seep O i l #4 Typical sample of pelagic t a r 3 5 I I . <0 I UVJU 152 points to tanker sludge as the usual source of pelagic tar. The metal analyses of 104 tar samples also indicate that tankers, and not natural seepage, are responsible for most of the pelagic tar. 77% of the samples contained greater than 1 part per thousand of iron. This represents an enrichment of at least one order of magnitude over the levels of iron in crude o i l (20% of the samples showed at least two orders of magnitude enrichment). In contrast, the nickel concentrations were not detectably above the levels In crude o i l , indicating that general metal enrichment was*not occurring in the tar due to scavenging of metals from sea water or concentration of metals during the weathering process. The alternative is that the iron has an anthropogenic source. Specifically, i t is likely that i t originates from the pickup of rust particles from tankers during the tank-washing process when the sludge is peeled off with high-pressure water jets (Butterworthing). Tar with low iron and wax contents may originate either from natural seeps or from spilt crude o i l . The formation of tar from both these sources has been observed: around the Santa Barbara o i l seeps tar is common on the beaches (eg. Coal Oil Point); and O'Sullivan (1971), among others, has observed the formation of tar lumps after a crude o i l s p i l l . It is not possible to dis-tinguish between these two sources using the analytical techniques described here, and no attempt has been made to do so. In Tables 19 and 21, the o i l industry has been given the benefit of the doubt, and tar with low wax content (12% of the samples) has been tentatively attributed to natural seeps. In summary, the correlation of tanker traffic to tar presence in the Pacific, the presence of long-chain paraffins, and the high concentration of iron in many of the samples a l l indicate that pelagic tar contamination in the Pacific originates primarily from tanker traffic, and from tanker sludge in particular. The standing stock of tar in the Kuroshio current system is, very -2 approximately, 25,000 metric tons, assuming 2.1 mg m average contamination 153 over the area bounded by 20°-40°N, 140°E-160°W. The residence time of the tar in this area, assuming a drift eastwards of 15 km/day (Dodimead et al, 1962), is about one year. Thus the yearly input to the area must be on the order of 25,000 metric tons. This'amounts to only 0.01% of the annual volume of crude o i l travelling the tanker route to Japan. That such a small percentage of the transported o i l should reach the ocean is not unlikely: 0.4% of crude cargoes in non-LOT tankers and 0.02% in LOT tankers are estimated lost during deballast-ing and tank-washing (Anon, 1971b). However, given the vast quantities being transported and the persistence of the tarry fraction, even a very small percen-tage loss results in significant contamination of the surface waters. 154 Chemical Weathering of Pelagic Tar Evaporation: Evaporation removes the lower-molecular weight components from pela-gic tar up to about pentadecane quite rapidly (probably over a period of several days for small particles, longer for larger masses) and reduces the amount of components up to the volatility of heptadecane (C-17). Figure 30 illustrates the effect of evaporation on a sample of crude o i l exposed to the atmosphere in a fume hood at room temperature. The exposure increased C... from less first than nonane (C-9) to pentadecane (C-15), and reduced the C-17/C-18 ratio from 1.4 to 1.1, indicating that these parameters are indeed measures of the effect of evaporation (the biodegradation index remained unchanged at 1.5). FIGURE 30: The Effect of Evaporation on the Composition of a Crude Oil #1 Prudhoe Bay crude o i l #2 Prudhoe Bay crude o i l 155 The chromatograms i n Figure 23 reveal the effect of evaporation on pelagic tar. The l i g h t e s t p a r a f f i n compound i n any tar sample was dodecane (C-12) which was found i n a large lump and a smaller piece i n the middle of the North P a c i f i c (28 N, 178 E). The most common f i r s t peaks i n the chromatograms were C-15 and C-17. Apparently the components up to C-15 are removed quite quickly, since no biodegradation i s evident i n samples with ^f^TSt= 15- (aver-age biodegradation index of 1.3). The loss of paraffins above C-15 does occur purely due to evaporation i n some samples, but more commonly an i n i t i a l peak of C-17 i s associated with extensive microbial degradation. Cle a r l y , the loss by evaporation of components above C-15 i s slow, and the process i s usually overtaken by microbial attack. I t i s curious that small p a r t i c l e s show no greater effect of evapor-ation than larger p a r t i c l e s . In f a c t , the C-17/C-18 r a t i o indicates less evapor-ation, i f anything, for small p a r t i c l e s (see Table 21 ). Furthermore, the analyses of samples from inside and outside a large lump f a i l e d to show the expected gradient of l i g h t e r compounds. I t was expected that more l i g h t compounds would be found i n the centre of the lump than i n the exter i o r , but no difference i n the composition could be distinguished. (See chromatograms 26, 27, and 28 i n Figure 23. ) Several observations made here contradict the model for evaporative weathering of pelagic tar proposed by Butler (1975). For the purpose of further discussion, the contradictions w i l l be noted. Butler's model assumes that the evaporation rate i s proportional to the equilibrium vapor pressure P of each compound and to the fra c t i o n of that compound remaining: dx , , v where x i s the o r i g i n a l amount — = -kP(x/x o) o x i s amount remaining at time t k i s an empirical rate c o e f f i c i e n t that varies with a variety of factors, including the size of the tar lump. 156 Such a model, when applied to the small particles of pelagic tar, requires either that they be very fresh, or that they have recently broken off larger, older lumps. The small particles cannot a l l be fresh, so Butler is forced to assume that they have broken off larger crude o i l masses with a median 3 size of 1000 cm . He concludes that the principal weathering processes are a combination of evaporative weathering and physical fragmentation to particles thousands of times smaller than the original o i l mass. Neither the extensive evaporative weathering nor the physical frag-mentation is evident from the data collected here: evaporation appears to con-sistently remove paraffins up to C-15 over a period of time, but beyond this the effect is minimal, and is overshadowed by the effects of microbial degradation. Similarly, the size distribution of particles does not indicate that physical fragmentation is occurring as the tar gets older. Furthermore, small particles do not show the effect of greater evaporative weathering that is predicted, and the expected diffusion gradient in the large tar lump is missing. Since pelagic tar is almost completely submerged in water at sea, and since i t has a very small surface area, i t may be that the rates of evaporation are very much reduced, leaving microbial degradation as the prime mechanism for long-term weathering. 157 Dissolution: The effect of d i s s o l u t i o n has not been distinguished from that of evaporation since the two processes affect the same components of petroleum. Evaporation has been shown to be the more eff e c t i v e process f o r weathering sur-face s l i c k s (Harrison et a l , see Chapter3 ), but this may not be the case for tar lumps. In the absence of any information to the contrary, i t has been as-sumed that evaporation i s predominant. Hence, i n the previous section, the removal of the l i g h t e s t components from pelagic tar has been attributed to evaporation rather than d i s s o l u t i o n , whereas i n fact some p a r t i t i o n i n g probably occurs. Photo-oxidation: As described i n Chapter 3:, photo-oxidation removes the isoprenoids from petroleum before the p a r a f f i n s , r e s u l t i n g i n the values for the C-18/C-19 rati o being decreased below the values found i n crude o i l . This effect i s not evident i n any of the tar samples analysed; instead, the r a t i o i s often substan-t i a l l y increased by the e f f e c t of microbial degradation. Thus the chromatograms indicate that photo-oxidation does not play a s i g n i f i c a n t role i n the degradation of pelagic t a r . This r e s u l t i s not surprising i n view of the very l i m i t e d surface area which i s available for absorption of l i g h t , and the opaque nature of the t a r , which prevents l i g h t from a f f e c t i n g anything but the surface layer of the p a r t i c l e s . Biodegradation: The C-18/C-19 r a t i o from the chromatograms provides clear evidence that microbial degradation i s important i n the weathering of pelagic t a r . The average value of the r a t i o for seventeen crude o i l s was 1.5 (based on data from Martin et a l , 1963), whereas the average r a t i o for the pelagic tar samples was 2.9 (33% of the samples had indices above 2). The average value of the index at the weather-158 ship, far from the probable source in the Western Pacific, is 5.6 indicating that by the time the tar reaches this portion of the Pacific, extensive degrada-tion has occurred. Unfortunately, the index is not a clear function of the longtitude as one would expect i f a l l the tar originated from the tanker route near Japan and was carried eastward by the prevailing currents. Figure 31 shows a plot of the index versus the longtitude at which the sample was obtained. Highly degraded tar is found in the western Pacific near the postulated source, FIGURE 31: Biodegradation Index (C-18/C-19 ratio) as a Function of Longtitude 8J, o 3 IT TT AA A A .5 10 t A A A A A A 2* A * * A , • A A £ A A i • 2* A 1 A3 A A I3(R R 0 ° 150° 160° 170° g(F i F iio° i60° 140s iJcFW l O N G T f T U D E O F N E U S T O N T O W S Dots indicate samples which appear to be natural seeps. Triangles indicate regular tar samples. Numbers indicate more than one sample from same location with same biodegradation index. 159 as well as in the eastern Pacific. This very weathered western tar may have originated in the Indian Ocean, or have travelled around the gyre in the western Pacific. The most degraded tar, with an index of has a remarkable consis-tency of composition (see Table 21). A l l eight samples were very similar despite coming from widely differing locations. Typically these samples have a C-17/C-18 ratio well below 1 (indicating the effect of prolonged evaporation); the first peak is 17; the maximum occurs at C-37, and the final peak is C-45. Tar which visually appears older, being brown or encrusted, has a significantly higher degradation index than tar which is black and fresh-looking. Thus the visual appearance does correlate to some extent with the chemical weathering. Interestingly enough, small particles of tar are usually less de-graded than larger pieces. Small pieces less than 0.1 g have an average index of 1.7, whereas pieces larger than 0.5 have an average index of 3.4. The reason for this phenomenon is not known. 160 Physical Weathering and Fate of Tar Tar pollution of the Atlantic and Mediterranean has resulted in ex-tensive contamination of beaches in some areas. It appears that the final rest-ing place of much of the pelagic tar in those locations is in the sand on beaches. In the Pacific, however, tar pollution of beaches is not common. Thus i t is not satisfactory to assume that the tar floats until i t is washed ashore. An experiment was conducted to determine the density of tar as a function of its apparent age and chemical composition. Tar samples were placed in beakers of fresh water to determine which lumps would sink. It was possible to observe definite classes of tar. Some was exceedingly bouyant, some was mar-ginal, and 4% of the particles sank. Although not a l l of the bouyant lumps appeared fresh, a l l of the samples which sank were very weathered. There was no size selection in the sunken tar, some particles being large and some small. A chromatogram of sunken tar is shown in Figure 32: i t reveals an advanced stage of decomposition. Also shown is a sample of abyssal tar dredged from the bottom of the western Gulf of Mexico (collected by Dr. Jeffrey of Texas A&M University). The abyssal tar is extensively degraded, having lost virtually a l l its paraffin components so that only the unresolved envelope remains. Since the paraffins are the lightest class of compounds in petroleum, their loss (by microbial action) increases the density of the tar lumps. In the case of the abyssal tar sample, the loss of the paraffins apparently resulted in the sinking of the tar. Chroma-togram 79 in Figure 23 shows the composition of a second tar sample which sank in fresh water. It shows some degradation, but is not as degraded as the sample in Figure 32; however, the lump was heavily encrusted with fouling organisms. Three samples obtained at ocean weather station P were obtained from tows made just below the surface. The chromatograms (#56, 57 and 58 in Figure23 ) indicate that a l l three samples were in a state of advanced decomposition: presumably they had a near neutral bouyancy, and were mixed below the surface by turbulence. The 161 FIGURE 32 : Chromatograms of a P e l a g i c Tar Sample w i t h High S p e c i f i c G r a v i t y and of an Ab y s s a l Tar Sample  TSDY 1; A4 53; 28N, 155W; 24 /6/73; f o r m a l i n ; 20/8 /75; 191 ( p o r t i o n of brown, p a r t i a l l y encrusted lump which sank i n f r e s h water) Abyssal t a r obtained by dredge from the western Gulf of Mexico (sample courtesy of Dr. L.M. J e f f r e y , Texas AM U n i v e r s i t y ) 162 actual increase i n density required to sink pelagic tar i s not large: the aver-age s p e c i f i c gravity of crude o i l s i s about 0.85 (tanker residues are probably s l i g h t l y denser), while the s p e c i f i c gravity of oceanic surface water i s about 1.025. Therefore an increase i n density of approximately 20% i s required for pelagic tar to a t t a i n a negative bouyancy. Some supporting observations exist i n the l i t e r a t u r e to suggest that the ultimate fate of pelagic tar i s sinking: Kinney et a l (1969) observed that a w a t e r - i n - o i l emulsion eventually became heavier than water due to b a c t e r i a l action; Spooner (1971), i n a laboratory experiment, found that bacteria sank crude o i l masses after several weeks; Heyerdahl (1971) observed tar as far below the surface as he could see during the Ra I I expedition; and Marumo and Kamada (1973) repeatedly found tar i n tows made at a few meters depth. In conclusion, the preliminary evidence indicates that the ultimate fate of pelagic tar i s to sink due to the gradual removal of the l i g h t e r compon-ents of the tar by the weathering processes, and the accumulation of an overburden of fouling organisms. The time required for sinking to occur i s presumably a function of the density and composition of the o r i g i n a l o i l , the time of innocu-l a t i o n of the tar with appropriate micro-organisms, and the fouling growth that develops. Judging from the d i s t r i b u t i o n pattern of the pelagic t a r , some p a r t i c l e s must d r i f t for periods on the order of years before eventually sinking. 163 Ecological Effects of Pelagic Tar The extensive contamination of the surface waters of the oceans by tar residues raises the question of the environmental impact that the residues have on the ocean ecosystem. Although no research on this matter was pursued during the course of this degree program, some comments can be made on the basis of general observations and information that has accrued in the literature. From observations made on the tar lumps collected in the Pacific, i t is evident that tar lumps enrich the biota of the surface layer by providing a substrate on which organisms can live and reproduce. The colonizing community typically includes bacteria and other micro-organisms (especially blue-green algae), chlorophyta, byrozoa, and Lepas barnacles. Isopods (Idotea metallica) are commonly found on tar lumps, and their colouring suggests that they may have adapted to this environment. Crabs are also found. They are usually s t i l l in the megalops stage, suggesting that they do not grow to maturity in their pre-carious habitats. Filially, the eggs of the oceanic water strider Halobates occur on about 2% of the tar lumps, so the tar apparently encourages this species as well. Beyond this superficial observation of the substrate role of tar, some more negative aspects must be considered. It is possible that organisms living on tar are not healthy, but suffer from sublethal effects that are not immediately evident. Some support for this proposition can be drawn from the observation of hyperplasia in bryozoa growing near coal tar (Powell et al, 1970). However, Morris (1973) found that barnacles growing on tar were not severely contam-inated by hydrocarbons. A second consideration is that tar may be injested by surface feeding organisms. This has been observed with copepods after an o i l sp i l l (Conover, 1971) and could result either in sedimentation of the tar in the feces, or passage up the food chain. The second possibility has not been documented. More directly relevant to the human condition is the occurrence of tar on the beaches over large portions of the globe. Tar is a pollutant around most 164 of the coastline of the Mediterranean (Anon, 1971), i n southern A f r i c a (personal documentation), the Caribbean (Sleeter et a l , 1976), Bermuda (Butler et a l , 1973), Florida (Dennis, 1959), B r a z i l (personal documentation) and around the entire coastline of India (Dwivedi and Parulekar, 1974). Many of these areas have very substantial t o u r i s t industries, for the seashore i s perhaps the favorite play-ground of the human race. The presence of tar reduces the recreational potential of beaches severely: highly contaminated beaches are not pleasant to walk along even i n shoes because of the heavy accumulation of tar which occurs; towels cannot be l a i d on the beach ; playing i n the sand r e s u l t s i n hands covered with tar , presenting an intractable cleaning problem without the use of organic s o l -vents; resort owners i n many locations provide solvents for t h e i r guests to clean thei r feet after venturing on the beach. Clearly the presence of tar damages the esthetic appeal and recreational value of a treasured environment. A f i n a l consideration i s that the presence of tar must be taken as an indication of hydrocarbons entering the water column. Although the p a r t i t i o n c o e f f f i c i e n t between crude residues forming tar and components entering the water column i s unknown, the presence of high concentrations of tar probably indicates that sizeable quantities of hydrocarbons are entering the water column. The b i o l o g i c a l effects of soluble hydrocarbons are considerably more serious than those of the non-soluble tar (see Appendix B), "The presence of tar may signal that hydrocarbons are entering the water column i n s u f f i c i e n t quantities to d i s -turb the balance of species and a l t e r the food chain dynamics (Parsons et a l , 1975; Fisher, 1976: see Appendix B). Conclusions 1. On the basis of 2092 surface tows between 1967 and 1975 the following conclusions were reached about the distribution of tar in the Pacific: a) Petroleum residues are not a significant pollutant in the surface waters of the South Pacific. b) In the Northeast Pacific occasional contamination of ^ surface tows occurs (average concentration is 0.03 mg/m ). c) The Northwest Pacific is the most contaminated area, particularly in the Kuroshio current system between 25° and 40°N. The average concentration in this area is 2.1 mg/m^ , which represents a standing stock of 25,000 metric tons of tar. 2. Plastic is a widespread contaminant on the North Pacific Ocean, but generally in lower quantities than tar. It usually occurs as round, colourless pellets weighing 20-50 mg each. 3. The Beaufort Sea in the Arctic Ocean is not contaminated by tar. Plastic, however, is a common contaminant on the beaches. 4. The distribution of the tar in contaminated areas is patchy, so that replicate tows catch widely varying quantities of tar which approxi-mately follow a log normal distribution. This patchiness cannot be explained on the basis of windrows, and probably is a result of the tar gradually spread-ing out from point sources. The tar distribution may be best represented mathematically by Newmann's contagious distribution. 5. Most tar particles were in the 1-5 mm range, but most of the tar mass was in particles in the 5-10 mm range. The largest tar lump was 5 cm in diameter and weighed 34 g. 6. The average water content of the tar was 22% by weight, which is considerably less than the amount of water in a fresh water-in-oil emulsion (80%). 7. Tar samples stored for a year and a half by refrigeration 166 or in formalin did not show any detectable change in composition. 8. Surface tows and beach surveys made in local British Columbia waters in an area of heavy urban and industrial development (including three o i l refineries).detected no petroleum residues, implying that the source of tar is not from run-off or refinery outfalls. 9. High iron concentrations of greater than 1 ppt were found in 77% of the 104 tar samples analysed (iron in crude o i l does not exceed 0.1 ppt). Nickel concentrations, however, were not detectable above those in crude o i l , so general metal enrichment did not occur. The anomalously high levels of iron strongly imply an anthropogenic source of the tar. 10. Gas chromatographic analyses provided a second and more pre-cise indication of the source of the tar. 88% of the 82 samples analysed con-tained long-chain, waxy paraffins of higher carbon number than C-25 in much greater abundance than they are normally found in crude o i l . These long-chain paraffins are typical of the sludge discharged by tankers when they clean their tanks after carrying crude o i l . This tanker sludge is probably the source of most of the pelagic tar in the Pacific. 11. The chemical analyses, combined with the distribution pattern of the tar, imply that most of the pelagic tar contamination in the Pacific originates from tankers on the very large Middle East to Japan tanker route, then becomes entrained in the Kuroshio current south of Japan and creates a plume of contamination which extends downstream for 7000 kilometers across the Pacific. 12. The standing stock of tar in the Northwest Pacific (25,000 metric tons) represents a loss of only about 0.01% of the o i l carried on the Japanese tanker route. However, because of the vast quantities being trans-ported and the persistance of the tarry fraction, even a very small percentage 167 loss results in significant contamination of the surface waters. 13. Photo-oxidation does not detectably contribute to the degrada-tion of tar. The role of dissolution is uncertain, but from theoretical con-siderations is presumed to be small. 14. Evaporation removes compounds up to the volatility of pentade-cane (C-15) from the tar: 73% of the 82 samples analysed had lost a l l n-alkanes up to C-15. Above C-15 the evaporative losses become very slow and the process is usually overtaken by microbial attack. 15. At least 33% of the tar samples analysed by gas chromatography showed clear evidence of microbial degradation. 16. Small particles of tar did not show any tendency to be further affected by evaporation or microbial attack than larger lumps. No gradient of lighter compounds between the inside and outside of a large tar lump could be detected, indicating that evaporation is not diffusion-limited. 17. Both evaporation and microbial degradation increase the density of the tar particles, and this effect combined with the weight of the fouling community that develops, results in the eventual sinking of the tar into the depths of the ocean. 18. Tar particles provide the biota of the surface of the ocean with a substrate on which they can live and reproduce. 19. Tar occurs as a pollutant on a very large portion of the world's beaches, including nearly a l l of the popular seaside resort areas. The pre-sence of the tar severely reduces the recreational and esthetic value of sandy beaches. CHAPTER 6 168 OIL IN THE INTERTIDAL ENVIRONMENT Introduction Although contamination of the intertidal environment by o i l has re-ceived a great deal of attention during and after various o i l s p i l l calamities, the scientific investigations are usually biological in nature and attempt to assess the biological damage. The number of chemical studies is far fewer: Blumer, Ehrhardt, and Jones (1973) followed the fate of stranded masses of petroleum in Massachussetts and Bermuda; Betancourt and McLean (1973) studied the weathering of intertidal o i l left after the Arrow s p i l l (the method of analysis - vanadium and nickel concentrations - did not allow them to determine the mechanisms of weathering). These are the only two studies which deal spe-cifically with the chemical weathering of intertidal o i l . The purpose of this research was to determine the rate and mechanisms of o i l degradation in the intertidal environment under local conditions, so as to provide some relevant information for the conduct of clean-up operations, and for the design of means for enhancing the natural degradation of o i l . The Alert Bay Oil Spill The study of the weathering of intertidal o i l was conducted by exam-ining the degradation of fuel o i l spilled by a freighter which grounded near the northern end of Vancouver Island, British Columbia. The accident occurred late on 24 January, 1973, when the freighter Irish Stardust ran aground near Haddington Island and spilled roughly 200 tons of heavy fuel o i l into Broughton Strait (see Figure 33). The majority of this o i l was deposited along the shores to the east by the receding high tide on the morning of 25 January (high tide of 14.6'). The town of Alert Bay on Cormorant Island was the community most affected.. Major clean-up operations were conducted on the beaches of Cormorant Island and other islands further to the east. However, one of the contaminated 169 bays was s u f f i c i e n t l y i s o l a t e d that i t could be l e f t undisturbed for s c i e n t i f i c study. This bay was code-named Reserved Bay, and f i v e v i s i t s were made to i t over the period of a year to obtain chemical samples and observe the n a t u r a l degradation of the heavy f u e l o i l . Description of the Study Area Reserved Bay i s a semi-exposed bay situated on the west side of the largest i s l a n d of the Pearse .group. The north and south sides of the bay are bounded by v e r t i c a l . r o c k faces f i v e to ten feet i n height. Its head i s bordered by a lowland of meadow and marsh grasses. A small stream flows onto the south end of the beach. The low-tide zone consists of a clay-based mudflat; the mid-tide zone of stone, sand, and pebble areas; and the high-tide zone of rock faces and patches of sand, stone, and pebbles. The area surrounding the stream i s mostly a sand-clay mixture. Rockweed (Fucus d i s t i c h u s ) extends from high to m i d - t i d a l areas. The low-tide mudflat harbours eelgrass beds (Zostera marina). Brown algae ( A l a r i a  marginata and Laminaira sp.) grow on logs which are p a r t i a l l y embedded i n the mud. Mud holes suggest the presence of clams, polychaete worms, and/or shrimp. Barnacles (Balanus glandulus), shore crabs (Hemigrapsus nudus and H. oregonensis), amphipods (Orchestia sp), periwinkles ( L i t t o r i n a sitkana and L. s c u t u l a t e ) , and turban s n a i l s (Calliostoma sp.) frequent m i d - t i d a l areas; while the l a t t e r three and the limpets (Acmaea spp.) are the prominent fauna i n the higher t i d a l zones. A p e c u l i a r c h a r a c t e r i s t i c of the bay i s the absence of the t y p i c a l s c a t t e r i n g of barnacles at the higher t i d a l l e v e l s . In general, this species composition i s t y p i c a l of i n t e r t i d a l l i f e i n a B r i t i s h Columbia semi-exposed h a b i t a t . Also, the p h y s i c a l c h a r a c t e r i s t i c s of the bay are common to thousands of i n l e t s and bays along the complex c o a s t l i n e of B r i t i s h Columbia and Alaska. Reserved Bay, then, provides a good 'case study' 170 of the environment which would be affe c t e d by an o i l s p i l l on the west coast. FIGURE 33: Locale of the A l e r t Bay O i l S p i l l Observations Reserved Bay was v i s i t e d f i v e times over a one year period to c o l l e c t samples f o r chemical a n a l y s i s . On each v i s i t the extent of o i l contamination and the appearance of the o i l were recorded, and a log of the more obvious b i o l o g i c a l events was kept. These observations are summarized i n Table 23. TABLE 23; Summary ot Observations, Q f the Oil Spill at Reserved Bay Date 30 Jan.73 (5 days after spill) Observations of Oil An oily sheen was on the surface waters of the cove; oil-soaked material and thick black patches of o i l floated near the beach. A band of o i l covered a vertical height of approxi-mately 2 meters downwards from the high tide mark. Coverage was continuous over rocks,rock faces, logs and seaweed, with a coating 1 to 5mm thick. The sand was oily but not coated. A thick bed of detached, heavily-oiled rock-weed (Fucus distichus)covered the high tidal area. Below the band of contamination the beach appeared to be totally oil-free. Observations of Biota 9 Mar.73 (6 weeks after spill) 5 Jun.73 (4% months after spill) 28 Aug.73 The areas of beach and rock contaminated by o i l were unchanged from the first v i s i t . No migration of o i l down the beach or to adja-cent unoil-Jareas had taken place. In general appearance the o i l looked remark-ably similar to the first v i s i t , except for being slightly less glossy and sticky. The location of o i l contamination was un-changed. The o i l had a dull,black, asphalt-like appearance, but s t i l l stuck to one's feet, leached a film of o i l into the water, and appeared fresh in crannies and under rocks. Oil was s t i l l very evident on rock and gravel portions of the beach. It was no longer noticeable in the sand. Exposed o i l was as-phalt-like in appearance. However, an o i l slick was s t i l l leached onto the advancing tide wherever the beach was disturbed. Smothering had killed many limpets (Acmaea spp.) on the heavily-oiled rockfaces (42 dead limpets were found at the base of a rockface 1 m2 in area. Many oil-covered amphipods (Orchestia sp.) were found. Most were alive but exhibited slow re-strained movements. Periwinkles (Littorina spp.) among the oiled rocks were lying free on the ground with their opercula tightly in position. Marsh grasses at head of beach were heavily oiled. The fauna and flora of the unoiled portions of the beach appeared to be unaffected. Nearly a l l limpets had died and fallen off heavily-oiled rockfaces. A few appeared to be success-fully grazing on the oiled rock. Meiofauna popu-lations in the sand were of normal diversity. Oil coverage of marsh grass was more weathered, and plants no longer stuck together in clumps. In spite of a sticky, oiled substrates, very high densities of amphipods were found ( 1000/m2). No recolonization of rockfaces by limpets or littorinids was evident. M Date Observations of O i l 26 Jan.74 S u p e r f i c i a l l y , the o i l had disappeared. It was no longer evident on the small (1 year , 1 stones of the beach, and on the rock af ter J - I - I N walls the dark s t a i n s of o i l were nearly S ^ gone. No o i l was evident i n the sand, and the o i l e d rockweed at the top of the beach had disappeared. Rocks and gr a v e l could be handled without the need f o r p l a s t i c gloves, although an unobtrusive t h i n black coating of o i l was s t i l l present on rocks i n some places. A few portions of the gravel beach were s t i l l immobilized by weathered, coagu-l a t e d o i l . O i l s t i l l leached into the water when the beach was disturbed. Observations of Biota The o i l e d marsh grass was reduced i n height r e l a t i v e to unaffected stands, but was s t i l l a l i v e . Limpets were beginning to r e c o l o n i z e portions of the rockfaces. Periwinkles were found i n areas previously devoid of them. 173 Chemical Analysis Oil samples from each visit to Alert Bay were analysed by gas chroma-tography to determine the chemical changes that occurred in the o i l due to the effects of weathering. Roughly one gram of material was weighed out from each sample into a centrifuge tube. Five milliliters of carbon disulfide were added and vigorously shaken to dissolve the o i l . The tube was centrifuged to remove sand and other particulate material, then the CS2 solution was decanted into a glass vial and refrigerated until analysed. The samples were run on two different columns: f u l l chromatograms were obtained using Dexsil 300 - a non-polar, high-temperature packing which can be programmed up to 400°C with very l i t t l e bleed; separation of isoprenoid compounds from paraffins was accomplished on FFAP, a polar packing. The ana-lytical parameters were the same as those used for pelagic tar analyses (see Table 18) . Table 24 gives the specifications of the fuel o i l of the Irish Stardust, as obtained from the fuelling report. TABLE 24: Specifications of Fuel Oil Spilt at Alert Bay Specific gravity at 15°C 0 .9412 Vis. R.W. No.l 465 Carbon 9.0% Flash Point Pour Point 10°C Sulfur 2.41% (Above information is from the fuelling report, Osaka, Japan. The fuel falls into the classification of No.5 fuel oil.) 174 FIGURE 34: Chromatograms of Fuel Oil Weathering in an Intertidal Environment l) Original o i l (taken directly from the fuel tanks of the Irish Stardust) 1 8 -* i 2 0 "l 2) After 5 days (thick slick floating near the beach). - i I I | : 1 ; : | : i | ! i 1 j l / : 3- --r- 4 4-4 -- -- -! : j T.i i i i 8 I -- - - i ; j 4 - - - - -j- 4 - --- 'T 14 --! -- - - - - 4 - - 4 -4 I i ! 1 > ! I - - - 44 - 4 4 - - 4 4-- •4--4 _ - - - - - H - - - - - 4-4-4-- 4- - --- -- - - - 4-4 - 4- - - 2 5 4 -!- - 4- - -- - ----- -_!_ - - - - i P w to - - -4 ~±. -- - -- - i ~ - - - ... %. • • i ' r -u 1 3 )" 4- --• - - - 4- - •- -- W -4~ 4-- -4- 4 -f — " 10 V : -i : -i — 4 44- 4--1- -4 - -I ; . i .-• I.:.: l . . I ; : I . . I :- . I • . I : . I 3) After 6 weeks (thick o i l between the rocks) 175 5) After 8 months (oiled surface gravel) 6) After 1 year (oiled surface gravel) sample 1 sample 2 1 76 FIGURE 35: Isoprenoid/Paraffin Ratios in Fuel Oil Weathering in an Intertidal Environment 177 Results of Chemical Analyses c Representative chromatograms from each visit to Reserved Bay are pre-sented in Figures 34 and 35. The parameters which indicate the effect of the various weathering mechanisms were calculated from these chromatograms and are listed in Table 25. TABLE 25: Characteristics of Fuel Oil Weathering in an Intertidal Environment From Figure 34 From Figure 35 Length of Exposure cio% n c50% n 17/env 25/env 17/Pr 18/Ph Pr/Ph Original 11.6 16.5 4.7 1.0 1.9 2.2 1.3 5 days 11.0 16.3 4.6 1.4 1.9 2.2 1.3 6 weeks 11.6 16.3 4,1 1.3 1.7 1.8 1.0 4^  months 14.8 18.0 3.0 3.1 1.2 1.2 .9 8 months 14.2 17.0 1.6 .1 .3 .2 .8 1 year,#l 14.3 17.2 1.7 .2 .3 .2 .8 1 year,#2 14.0 17.1 1.5 1.0 .2 .3 .8 Note: 107 507 C and C refer to the equivalent n-paraffin carbon numbers at which the n n unresolved envelope reaches 10% and 50% respectively of its maximum amplitude. 178 Discussion of Intertidal Weathering The chromatogram of o i l from the tanks of the Irish Stardust is vir-tually identical to that obtained 5 days later near the beach at Reserved Bay. If the source of the polluting o i l had been in doubt, these two chromatograms would have provided convincing evidence that the o i l came from the Irish Star-dust. Virtually no evaporation or dissolution occurred over the first 6 weeks, 10% 50% the C ° and C ° values remained unchanged. Between 6 weeks and months n n the values suddenly increased. This coincides with the summer season, and is perhaps due to the increased temperatures in the sun-heated o i l , causing in-creased evaporation. After 4^  months no further evaporation or dissolution is evident. The ratio of paraffins to isoprenoids began to decline after 6 weeks and dropped markedly between 4^  months and 8 months, indicating the pronounced effect of microbial degradation. If any photo-oxidation occurred, its effect on the paraffin/isoprenoid ratios was competely masked by microbial degradation. The chromatograms show the steady advance of degradation until, after about a year, the paraffins were completely degraded, leaving an unresolved envelope. By comparison, bacteria under culture conditions can completely remove paraffins from o i l within 24 hours (see Figure 8). Blumer, Erhardt, and Jones (1973) found that the alkanes were depleted from intertidal crude o i l within 4 months when nutrients were available (from decaying plant material) but were not degraded during the 16 months of the study for samples on rock. The two chromatograms of one year samples (Figure 34, #6) also show some variations by locale. Both are samples from oiled gravel, but one is considerably more degraded than the other (25/env ratios: 0.2 vs. 1.0), which presumably is a result of differing surface areas or availability of nutrients. The chromatogram of the 4^  month sample (Figure 34, #4) has an inter-179 esting anomaly - there is an enrichment of the longer-chain paraffins relative to the original sample (the 25/env ratio has tripled). There is no known weathering mechanism which cause polymerization of alkanes, so this sample apparently had an inclusion of wax resulting from wax precipitation either in the tanks of the Irish Stardust or after the s p i l l . Conclusions 1. Microbial degradation was.responsible for the chemical weathering of the spilt o i l at Reserved Bay. Evaporation played only a minor role; photo-oxidation and dissolution did not appear to have any effect. 2. Microbial attack took approximately 1 year to complete the degradation of the paraffins in the spilled o i l , leaving an asphalt-like residue on the stones of the beach. The asphaltic residue was apparently more susceptible to physical weathering than the original o i l . 3. The combined effects of chemical and physical weathering removed about 95% of the spilled o i l from the cove over the period of one year. Several factors must be considered in applying this measurement of the degradation rate to other situations: a) Since microbial action is the prime mechanism for degrading intertidal o i l , a source of nutrients is essential. In Reserved Bay an ample supply was available from the decaying rockweed at the head of the beach. Bare rock is the poorest environment for nutrient supply. There i t may be most e f f i -cient to add nutrients in the form of an oleophilic solution to encourage degradation, rather than attempt financially and ecologically expensive clean-up procedures such as sand-blasting, steam-cleaning, or the applica-tion of detergents. b) The rate of degradation is very much a function of the amount of o i l spilled per unit area. The time required for degradation does not appear to vary 180 linearly with increasing o i l contamination, but exponentially, partly be-cause of the decreased surface area per unit volume for evaporation and microbial attack, but also because heavy contamination may result in 'immobilization' of the beach. Immobilization occurs when the asphaltic residue from spilled o i l effectively paves the intertidal area, preventing natural beach overturn and so eliminating most of the physical weathering. Several beaches were immobilized by the Arrow sp i l l (Task Force - Operation Oil): a measurement of the extent of weathering by Betancourt and McLean (1973) indicated that about 20% loss of material occurred over a one year period, after which chemical weathering appeared to have stopped. The rate of natural degradation is dependent on the type of o i l spilled. Light petroleum products such as diesel fuel disappear more quickly because of the increased importance of evaporation and dissolution, but have more severe biological effects. The rate of weathering depends on the exposure of the beach. Intertidal areas with open ocean exposure should purge themselves of o i l contamination considerably more quickly than the semi-exposed location at Reserved Bay: the greater energy of the beach leads to increased physical weathering, thereby increasing the surface area of the o i l and the rate of chemical weathering. CHAPTER 7 181 OIL IN THE BENTHIC ENVIRONMENT Introduction There have been a number of publications dealing with sinking agents as a method of treating o i l s p i l l s (Houston et a l , 1972; Arthur D. L i t t l e , Inc., 1969; Warren Spring Laboratory, 1972; Water Quality Laboratory, 1969; Brown, 1971). These publications compare the effectiveness of various sinking agents, and evaluate the general effectiveness of the method i n comparison with other o i l treatment procedures. Several of these publications indicate the need to know something of the rate of degradation of o i l which has been a r t i f i c i a l l y sunk, but nothing has appeared i n l i t e r a t u r e to date dealing with t h i s problem. The information i s necessary to establish the propriety of using sinking agents, and i t also provides further insight into the manner i n which the natural environment deals with the sudden in t r u s i o n of petroleum chemicals. The purpose of the experiment described i n t h i s chapter was to determine the rate at which crude o i l degradation took place under i d e a l conditions i n a previously p r i s t i n e environment, and to est a b l i s h the mechanisms of degradation. Method Two l i t e r s of seawater were placed i n a four l i t e r container l i n e d with a p l a s t i c bag. 500 ml of Peace River crude o i l were added, giving a surface s l i c k 2 cm thick. 1000 - 2000 ml of sinking agent - a dried, untreated volcanic • ash - were added to the container, sinking the o i l . The water was poured o f f , and the bag ti e d closed. Four samples were prepared i n this manner. The four bags of sunken o i l were taken to Dodger's Cove, i n Barkley Sound, a shallow (5-7 m) s i l t y area with currents of up to 1 knot. The contents 2 of each bag were spread by divers over i n d i v i d u a l quadrats of about 0.25 m , and covered with h inch mesh f i s h netting which was staked into the s i l t to prevent d r i f t i n g and to mark the s i t e . 182 The sites were sampled according to the following schedule: r • • " - Time after Commencement Commencement of experiment: 9 Feb. 1974 First sampling: 7 Mar. 1974 1 month Second sampling: 25 Jul. 1974 5% months Third sampling: 7 Jun. 1975 16 months o Samples were preserved both with formalin and by refrigeration (-18 C). The samples were analyzed by gas chromatography. About 0.5 g of sample were shaken with CS^, centrifuged, and 5-40 ul were injected into a Varian Aero-graph 1400 gas chromatograph. Two columns were used, a high-temperature Dexsil column for obtaining a f u l l chromatogram, and a polar FFAP column for separating the isoprenoid compounds from the alkanes. The technical data is the same as for the analyses performed on pelagic tar as detailed in Table 18-Observations When the o i l was released from its bag on the bottom and spread over the quadrat, some of the o i l escaped and bubbled to the surface. The percentage loss is hard to estimate, but was probably in the neighbourhood of 5-10%. One month later, a l l four quadrats bubbled o i l to the surface when disturbed. After 5h months, at the time of the second sampling, one quadrat bubbled o i l , and a l l showed obvious o i l contamination which appeared fresh. By the time of the third sampling, 16 months after contamination, a l l quadrats were covered with about a centimeter of s i l t . The o i l contamination was no longer obvious, and no o i l es-caped to the surface when the sediment was disturbed. It was difficult to t e l l what to sample when diving, and upon reaching the surface, the only way of determ-ining i f oiled sediment had been obtained was by the smell of the o i l . The odour of o i l was s t i l l clearly evident in the sediment samples. 183 Results of Chemical Analyses The ful l gas chromatograms obtained from the samples are shown in Figure 36, and the chromatograms obtained with the polar FFAP column are shown in Figure 37. The parameters calculated from, these chromatograms are tabulated in Table 27. It was discovered during this investigation that formalin preserves heavily-oiled samples more effectively than refrigeration. The evidence for this conclusion, is presented in Figure 38. (All chromatograms in Figure 36 and 37 were of samples preserved in formalin.) 184 FIGURE 36: Chromatograms of Crude Oil Weathering in a Benthic Environment l) The original o i l : an Alberta crude (anal. 1 7 / 8 / 7 5 ; £L66) • li 17 10 15 18 20 I 2.5 J 2) After 1 month (sampled 7 / 3 / 7 4 ; formalin; anal. 1 7 / 8 / 7 5 ; #169) 10 17 15 18 20 U 25 30 35 3) After 5g- months (sampled 2 5 / 7 / 7 4 ; formalin; anal. 6 / 6 / 7 5 ; #L3) 185 FIGURE 36: continued 4) After 16 months, sample 1 (sampled 7/6/75; formalin; anal. 4/7/75; #42) ' i 1 1 ! ! 1 r 1 ' • — 1 i .! i ! ! > i : . i ! i . •........ . i-4— M U M I • : _ ; _ — . — •j. ! M M M ! ! 1 ; | ; i ' ' ' ! | ' I : — 1 1 i ! i ! ! M i | • : ; I ! ! M ' ! i -1 ! - --•- .... ! ' •' - 1 — L i : 3C ) " ™ ; ~ 1 J ! j M : 1 J . — - OR - .. : ! i i ! !' i ! i ; 15 I ! ! i ! 1 | j i I: -ll 20- - .14-- - ! I -• 135 "YVWAv40 — i 1 1 1 1 ! 1 : i 1  I M M M M f1' ii / W r m w M M M M —A 1 ; t i i M f\ ! 1 1 M i • I I i ! 1 ! i 10 \ir . j j j • • ! : | 'j I ! j I r "i—f— r— W-* Ni .. 1 1 • ! ! ! : • i i • | ; : ; — -'M i M U / I i I-" M M : - L i : I • i j • : M " i M • : i - ' l M • i i M - M . : - . - J . - J . - M i . !. i • - \ --! -i I- 1 1 5~l ..!.. J. 5) After 16 months, sample 2 (sampled 7/6/75; formalin; anal. 7/7/75; #45) 15 186 FIGURE 37: Isoprenoid/Paraffin Ratios in Crude Oil Weathering in a Benthic Environment l) Original o i l (Alberta crude) 20 2) After 5g- months 3) After 16 months 187 Preservation of Heavily-Oiled Samples To check on the integrity of the methods of storage of o i l samples, duplicate samples of heavily-oiled sediment from the benthic experiment were stored in formalin and by freezing for 10% months, analysed in the usual manner, and the chromatograms compared with an analysis made on the fresh sample. The chromatograms of the samples stored by the two methods are compared in Figure 38, and summarized in Table 26. It is immediately clear that the frozen sample lost some of its volatile .components over the period of storage despite the cold temperatures and screw-top glass container in which it. was kept - three-quarters of the C-9 and C-10 peaks were lost relative to C-17, and the effects of evapor-ation extended up to and included C-13. The sample preserved in formalin, how-ever, did not change in composition. Thus, although formalin may contain trace hydrocarbons that make i t unsuitable for preserving sediment and tissue for trace analysis, it is sufficiently pure for preserving heavily-oiled samples, and very effectively eliminates evaporative losses. TABLE 26: Comparison of Refrigeration and Formalin as Methods of Preserving Heavily-Oiled Samples  Storage Peak Heights Relative to C-17 9/17 10/17 11/17 12/17 13/17 14/17 15/17 None .82 .81 .88 .93 .96 .94 .84 10% months in formalin .85 .76 .98 1.02 1.00 .99 .89 10% months frozen .26 .27 .65 .79 .88 .93 .86 188 FIGURE 38: Chromatograms showing the E f f e c t of Storage on Preserved O i l Samples . l ) Sample preserved f o r eleven months i n formalin (sampled 25/7/74; formalin; anal. 12/6/75; #25 - no change from o r i g i n a l chromatogram) 2) Sample preserved f o r eleven months by refrigeration at -18 C (sampled 25/7/74; freezing; anal. 12/6/75; #23 - note loss of lower-boiling components) i r __ 11. • 189 Discussion None of the four quadrats of sunken o i l underwent any change i n chem-i c a l composition during 5% months of exposure on the bottom of Dodger's Cove. The rate of degradation was so slow that the quadrats were not sampled again for nearly a year. After 16 months the o i l had begun to degrade. Chromato-grams #4 and #5 (Figure 36) show the range of degradation which had occurred. In sample 1, alkanes up to about C-20 were removed and p a r t i a l losses occurred up to C-25 (see Table 27) . The degradation of the sample i s c l e a r l y caused by microbial attack, since the paraffin/isoprenoid r a t i o s drop d r a s t i c a l l y for this sample (17/Pr from 1.4 to 0.1; 18/Ph from 1.6 to 0.3). As i n one sample from the i n t e r t i d a l experiment, this sample shows a mysterious.enrichment of the long-chain paraffins between C-25 and C-35 (C-30 r a t i o double the o r i g i n a l o i l sample r a t i o - see Table 27). Again, this must represent some sort of wax inclusion caused by p r e c i p i t a t i o n of waxes. The second chromatogram of a 16 month sample i s from the least degraded of the quadrats. In this sample the alkanes had only been reduced up to about C-20, but again there i s clear evidence that microbial attack i s responsible. The degradation process was slower i n the benthic environment than i n the i n t e r t i d a l s i t u a t i o n already discussed. The reason may be that, i n the benthic environment, evaporation has no opportunity to remove the toxic short chain components (C-5 to C-8) which are b a c t e r i c i d a l to many species of microbes (Button, 1971). Dissolution did not appear to be effe c t i v e i n removing these v o l a t i l e components: for 5% months the composition of the o i l did not change - i f no disso l u t i o n occurred over this long period, i t i s u n l i k e l y that i t occurred at a l l . More l i k e l y , the toxic components were eventually removed by microbial action. Since only a few species are capable of degrading the l i g h t -est components of petroleum, the seeding time i s long and the degradation slow. Once the l i g h t e s t components are degraded, seeding of the o i l by many other 190 TABLE 27: Characteristics of Crude Oil Weathering in a Benthic Environment a) From ful l chromatograms (Figure 36): Length of Exposure 11 15 17 20 25 30 Original .89 .87 1.03 .31 .20 .07 1 month .95 .88 1.00 .31 .21 .08 5h months .88 .78 .89 .35 .14 .05 16 months - sample 1 .05 .10 .39 .05 .12 .16 - sample 2 .11 .34 .63 .22 .20 .09 (for each chromatogram, peak heights have been normalized by dividing by 4 times the height of the envelope at C-17.) b) From partial chromatograms (Figure 37): Length of Exposure 17/Pr 18 /Ph Pr/Ph Pr/env Ph/env Original 1.43 1.63 1.48 .83 .56 5h months 1.38 1.64 1.47 .90 .58 16 months .14 .29 1.62 1.07 .59 191 strains of bacteria, fungi, and mold can occur, and microbial attack can begin in earnest. Thus the slow degradation of the benthic o i l can be explained as an i n i t i a l delay followed by the same process of microbial degradation as oc-curred in the intertidal environment, probably at about the same rate (1 year to remove the paraffins). It will be noted that photo-oxidation has not been mentioned as a weathering process in this discussion. The paraffin/isoprenoid ratios show clearly that microbial degradation is -the dominant process, and any photo-oxi-dative effects are completely masked. Since light of the correct wavelength (less than 300 nm) will only penetrate a few meters into the ocean, i t is un-likely that any photo-oxidation of the petroleum occurred. Finally, i t should be noted that pristane occurs widely in sediments (Blumer and Sass, 1972b). Caution must be exercized, therefore, in assuming that the pristane quantities in the benthic o i l samples are conservative. The pristane/envelope ratio (Table 27) increased by about 29% over the period of the experiment. Since the phytane/envelope ratio did not change, some enrich-ment of the samples by pristane from the sediment is indicated. Conclusions 1) Heavily-oiled samples should be preserved in formalin i f they are to be stored for any length of time prior to analysis, since the formalin not only prevents bacterial alteration, but also eliminates evaporative losses which can occur i f the samples are stored by refrigeration. 2) The degradation of the benthic crude o i l resulted almost entirely from micro-bial action. Evaporation had no opportunity to act; dissolution was ineffec-tive; and photo-oxidation was not possible because of the low energy and intensity of the light reaching the sediment. 192 3) The benthic petroleum samples were slow to degrade: the o i l remained un-changed in chemical composition for at least six months; even after 16 months the paraffins, which are the fraction most susceptible to attack, were only partially degraded. 4) The pattern of degradation appeared to consist of an i n i t i a l delay while bactericidal components were dealt with, followed by microbial degradation of the remaining o i l at roughly the same rate as in the intertidal experi-ment - one year to remove the paraffin components. The following factors limit the generality of the measured rate of degradation of the o i l in this experiment: a) The conditions in Dodger's Cove are ideal for microbial growth. The sedi-ment is thick, soft, and aerobic, with an abundant supply of detritus. A gentle tidal current maintains flushing and a supply of nutrients. In other situations, such as at great depth or in areas of nutrient limitation, the conditions for microbial growth may be less suitable, and result in slower degradation. b) The sunken o i l was a fresh crude, and so contained a high percentage of light components in the C-5 to C-8 carbon number range. These compounds are toxic for most species of microbes, and so greatly inhibit microbial degradation. If the sunken o i l had been a heavy fuel o i l or a weathered crude, then the bactericidal components would not have been present, and bacterial degrada-tion would have proceeded more efficiently. c) Dodger's Cove is in a pristine area distant from any industrial or urban centre, so there is no adaption of the bacterial fauna to petroleum degrad-ation. In areas chronically polluted by petroleum, seeding and consequent bacterial degradation should be considerably more rapid. 193 CHAPTER 8 OIL IN THE WATER COLUMN Introduction The purpose of the experiment described in this chapter was to deter-mine the fate of hydrocarbons that enter the water column, and to test in a controlled situation the validity of the analytical methods that are employed in hydrocarbon determinations. The determination of the quantities and composition of hydrocarbons in the water column is a difficult analytical problem because of the immense diversity of the hydrocarbons, the very low levels at which they dissolve, and the complex matrix of organic compounds from which they must be separated.. Sampling oceanic waters for hydrocarbons requires a degree of caution which has frequently not been exercised in reported studies. Gordon et al (1974), in a classic demonstration of the hazards of hydrocarbon sampling, found that they obtained the same concentrations of hydrocarbons whether or not they actually collected water samples with their Knudsen bottles. They recommended that the surface of the sampler not come in contact with any water except that being sampled, and that the sampler be rinsed with solvent after sampling to recover hydrocarbons adsorbed on the walls. The rinsing of the sampler with solvent precludes the use of plastic containers because of the danger of contamination by plasticizers. The most common analytical methods for the detection of hydrocarbons in seawater are: infrared absorbance (Brown, 1973, 1975; Monaghan, 1973); fluorescence spectroscopy (Levy, 1971, 1972; Gordon et al, 1974; Cretney and Wong, 1974); and gas chromatography (Barbier et al, 1973; Hardy et al, 1975). Of the three methods, fluorescence is the most sensitive, but responds only to very specific polyaromatic compounds, gives l i t t l e information on composi-tion, and is prone to interference from non-hydrocarbons such as chlorophyll. 194 Infrared spectroscopy detects a broad spectrum of hydrocarbons in a single signal (CH 3- or CH 2~ groups) but again gives l i t t l e information on composi-tion and is prone to interference from non-hydrocarbons. Both the infrared and the fluorescence method require the use of an arbitrary calibration standard to convert instrument response into concentrations. Gas chromatography can reveal much information on the composition of the hydro-carbon extract, but thereby sacrifices sensitivity and requires more time and s k i l l for analyses. The problems of interference can be overcome by using column chromatography (Cretney and Wong, 1974; Brown et al, ly73, 1975) or thin.layer chromatography (Barbier et al, 1973); sensitivity can be enhanced by extracting larger quantities of water (Barbier et al extracted approximately 100 1 using 9 liters of solvent I). However, the preparative methods and the increased volumes of water increase the ever-present risk of contamination. The utmost caution is required: solvents often are not sufficiently pure even after multiple distillation; atmospheric hydrocarbons may contaminate samples left open; glassware must be meticulously cleaned and transfers minimized; plastics must be scrupulously avoided; and a l l chemicals must be soxhlet-extracted before use. Filtration can have pronounced effects on the results because much of the 'dissolved' hydrocarbon material occurs adsorbed on s i l t and other particulate material. Furthermore, adsorption on the f i l t e r may occur. Finally, the samples must be guarded against microbial degradation and evaporation (especially during roto-evaporation of solvents). In general, the sampling and analytical methods require very meticulous attention, and i t may be that many of the values reported in the literature are unreliable (Gordon et al, 1974). The methods and results of some of the more prominent investigations of hydrocarbons in the water column are summarized in Table 28. There has been a tendency for values to decline with later publications (Gordon et al, TABLE 28: Reported Concentrations of Nonvolatile Hydrocarbons in Oceanic Waters Reference Location Depth Concentration (ug/liter) No. of Samples Extraction Solvent Analytical Method Column Filtra-tion? Sampling Method Barbier et al, 1973 European coast & off West Africa 0 to 4500m 10-137 (8) CHCL3 (9 Litres) g.c. t.l.c. (silicic acid) yes 130 liter teflon bottle Hardy et al, 1975 North Sea & U.K. coast-al waters surface film 1 m 34 ± 28 ug/m2 2. + 2.0 (40) (85) pentane g.c. (alkanes only) s i l i c i c acid yes s. s. screen bucket Levy, 1972 Nova Scotia coast 2 and 10 m 1.7 + .7 (24) CC1. 4 fluor. (Bunker C standard) none no oceano-graphic bottles Gordon et al, 1974 Halifax-B^ermuda section 0-3 mm 1 m 5 m 20 ± 61 0.8 ± 1.3 0.4 + 0.5 (43) (24) (24) CH2C12 fluor. (Venezuelan crude standard) none no special device Cretney & Wong, 1974 Northeast" Pacific 0 m .018 ± .006 (9) CH2C12 HPLC- fluor. (chrysene standard) silica gel no bucket Brown et al, 1973 Venezuelan tanker routes 0 m 10 m 8.9 * 9.6 3.9 ± 3.6 (33) (25) CC1. 4 i. r . (crude o i l standard) silica gel no bucket sea water line (from tankers) Brown et al, 1975 Mediterr. Mediterr. Deep Sea profile (nr Bermuda) 0 m 10 m 0-30 m 50-2500m 27 db 54 3.6 + 2.0 3.8 ± 1.4 0.8 + 0.8 (19) (15) (7) (16) CC1. 4 i. r . (crude o i l standard) silica gel no bucket sea water line 30 1 Niskin 30 1 Niskin «5 ' Ln 196 1974) and this trend may continue. I t has been established, however, that there i s a surface f i l m high i n hydrocarbons (Duce et a l , . 1972), that surface waters from 0 to 10 m are r e l a t i v e l y high i n hydrocarbons (0.5 to 30 ug/1 depending on location and method), and that deep waters are r e l a t i v e l y low i n hydrocarbons «1 ug/1, often below the detection l i m i t ) . A calculation can be made of the standing stock of hydrocarbons i n oceanic waters based on these estimates of hydrocarbon concentrations. The following concentration p r o f i l e i s assumed: 0 m - 6 ug/1 10 m = 3 ug/1 1000 m = 1 ug/1 2000 m = 0 ug/1 (t o t a l volume of ocean - 1.37 x 1 0 ^ l i t e r s ) . Integration of th i s p r o f i l e gives an estimate for t o t a l hydrocarbons i n the oceans of about 400 m i l l i o n metric tons. Petroleum input has been estimated at 6 mta (chapter 1) and biogenic hydrocarbon production at 3 mta (Revelle et a l , 1971) to 10 mta (Button, 1971). These figures imply that the residence time of hydrocarbons i n the water column i s about 10 to 100 years. The most important measurement required for environmental manage-ment i s the d i s t i n c t i o n between biogenic and petroleum hydrocarbons. Direct d i f f e r e n t i a t i o n i s not possible at the present state of the a r t , but in d i r e c t inferences have been made. Two i n d i r e c t approaches i n p a r t i c u l a r have been attempted. Monaghan et a l (1974) and Brown and Huffman (1976) r e l i e d on the determination of the hydrocarbon/lipid r a t i o i n a clean environment (about 0.2), then attributed increases i n the r a t i o to petroleum p o l l u t i o n . Barbier et a l (1973) compared the spectrum of hydrocarbons i n the water column to those i n phytoplankton, a t t r i b u t i n g differences to the presence of petroleum hydrocarbons. Clearly both methods have many unknowns, and di f f e r e n t conclu-sions have been reached. Brown and Huffman (1976) f e l t that most of the hydro-carbons they measured were anthropogenic, while Barbier et a l noted the simi-l a r i t y i n hydrocarbon composition of seawater and algae, and hypothesized that most oceanic hydrocarbons are natural products. The issue remains 197 unresolved. , Zsolnay (1973c and 1974b) has noted a correl a t i o n between chlorophyll and hydrocarbon concentration, suggesting that a portion of the regional differences i n hydrocarbon concentrations i s due to differences i n photoplank-ton populations, rather than purely due to anthropogenic input. Boehm and Quinn (1973) have noticed that dissolved organic compounds i n the seawater increase the s o l u b i l i t y of alkanes but not aromatics. Anderson et a l (1974) have shown that the spectrum of dissolved hydrocarbons present i n the water column d i f f e r s from the p o l l u t i n g o i l by being enriched i n aromatics r e l a t i v e to p a r a f f i n s . Brown and Huffman (1976) speculate that, of hydrocarbons enter-ing the water column, cycloalkanes are the most persistent, and aromatics the least (alkanes not considered). A l l of these considerations complicate the determination of the source and fate of dissolved hydrocarbons i n the environment. 198 Experimental Method The experiment was conducted in floating polyethylene enclosures 2 m in diameter and 15 m deep, fi l l e d with about 60 tons (60,000 1) of seawater. These large bags were available as a part of the Controlled Ecosystem Pollution Experiment (CEPEX) which is being conducted in Saanich Inlet. They are termed Controlled Ecosystem Enclosures (CEE's) and have been described by Parsons (1974) and Takahashi et al (1975). Two columns were used in this experiment, one of which was treated with o i l ('G'), and the other kept as a control ('F'). Oil was added to enclosure G in the following manner: carboys con-taining 17 liters of seawater from the CEPEX site were stirred for 24 hours with 35 ml of #2 fuel o i l (American Petroleum Institute standard); the phases were allowed to separate for 12 hours; then the water extract from each of 10 carboys was pumped through a diffusion ring into the water column of the enclo-sure. No surface slick resulted from this addition, indicating that the petroleum hydrocarbons remained dissolved. The date of addition was 11 June, 1975. A second addition of fuel o i l was made a week later (20 June) following the same procedure except that 10% ethanol in seawater was used to increase the solubility of the o i l , and so to decrease the volume of addition required. Al l of the oil.was added at 8 meters using the diffusion ring; in this case a small amount of o i l came to the surface as a slick, which disappeared in a few minutes. Sampling: Prior to the addition of the spike of fuel o i l , sampling was conducted to establish the background levels. After the addition, both the control bag and the polluted bag were sampled on a regular basis at 1, 7, and 13 m depth. The program of sampling was repeated for the second spike of fuel o i l . Samples were obtained by hand-lowering a Niskin bottle into the CEE's. The water samples were drained into 4 liter glass bottles with teflon-lined screw caps, 199 preserved w i t h ca. 100 mgmercuric c h l o r i d e , and stored i n a c o o l e r a t 5°C. ( P r i o r to use, the four l i t e r b o t t l e s had been r i g o u r o u s l y cleaned w i t h chromic a c i d , d i s t i l l e d water, methanol, and pentane.) A l a r g e r volume of sample was d e s i r e d f o r the gas chromatographic analyses. 20 l i t e r carboys were f i l l e d u s i n g a diaphragm pump, preserved w i t h EgCl^t and stored i n a c o o l e r . Sediment samples were c o l l e c t e d from the bottom of the CEE's every three days f o r hydro-carbon analyses, so that the extent of hydrocarbon sedimentation could be a s c e r t a i n e d . F i n a l l y , an extensive program of b i o l o g i c a l and n u t r i e n t sampling was conducted by the s t a f f of the CEPEX experiment. The parameters measured i n c l u d e d : composition and abundance of major phytoplankton and zooplankton po p u l a t i o n s ; n i t r a t e , phosphate, and c h l o r o p h y l l determinations. Hydrocarbon Analyses: Fluorescence analyses were conducted on the 4 l i t e r samples c o l l e c t e d w i t h N i s k i n b o t t l e s . The samples were analysed by e x t r a c t i n g 1.5 l i t e r s of water w i t h 90 + 60 ml of methylene c h l o r i d e i n a separatory f u n n e l . The e x t r a c t was rotoevaporated to dryness, the r e s i d u e taken up i n 1 ml of hexane, and 0.5 ml i n j e c t e d i n t o a high-pressure l i q u i d chromatograph w i t h a s i l i c a g e l column (see Table 29 f o r o p e r a t i o n a l parameters). The f u n c t i o n of the column was to s t r i p p o l a r m a t e r i a l , such as c h l o r o p h y l l and other pigments, from the sample and pass only the hydrocarbons. The e l u t a n t from the column passed through an u l t r a v i o l e t detector which measured absorbance at 263 nm, and through a f l u o r e s c e n c e detector which e x c i t e d at 308 nm and measured the emitted l i g h t at 383 nm. (The f l u o r e s c e n c e wavelengths are optimum f o r chrysene and s u i t a b l e f o r the d e t e c t i o n of most o i l s - Johnson et a l , 1973.) The f l u o r e s c e n t response was recorded on a Honeywell r e c o r d e r , and q u a n t i f i e d by c a l c u l a t i n g the peak area and comparing to a chrysene standard. The samples f o r gas chromatographic a n a l y s i s were e x t r a c t e d w i t h pentane i n a continuous l i q u i d - l i q u i d e x t r a c t o r which allowed l a r g e volumes to be e x t r a c t e d using moderate amounts of s o l v e n t ( f o r a d e s c r i p t i o n of the 200 TABLE 29: Instrumental Parameters for Hydrocarbon Analysis of Seawater Fluorescence Analyses Instrument: Column: Solvent: Flow rate: Pressure: Chart speed: Fluorescence Waters Associates model 202/401 liquid chromatograph inter-faced with a Perkin-Elmer model 204 fluorescence spectro-photometer by a flow-through cell (0.1 ml internal volume) 150 mm x 1.8 mm column packed with 5 micron silica gel (LiChrosorb Si-60, E. Merck Co.) hexane 1.2 ml/min Approx. 2000 psi 0.5 inch/min (Honeywell recorder) spectrophotometer settings: exciter wavelength 308 nm analyser wavelength 383 nm Gas Chromatographic Analyses Instrument: Hewlett-Packard model 5710A Column: 7' x 1/8" 2% OV-7 on 80/100 mesh Chromosorb W (HP) Carrier gas: He Temperature programming: i n i t i a l 100°C (2 min) final 270-C (4 min) rate 8°C/min Chart speed: 0.5 inch/min Detector: FID Sensitivity: variable 201 extractor see Werner and Waldichuk, 1962). For each carboy sample, two 5-7 liter subsamples were extracted with 300 ml pentane, the pentane rotoevaporated to dryness, and the residue taken up in 1 ml of hexane. 0.5 ml was then injected into the high-pressure liquid chromatograph with the same operating parameters and column used for the fluorescence analyses. The elutant from the liquid chromatograph was collected, rotoevaporated, the residue taken up in 500 ul of CS2, and 100 ul injected into the gas chromatograph (operating parameters as given in Table 29). Peaks in the gas chromatograms were identi-fied by retention times, and quantified by peak heights relative to an internal standard. Finally, a few infrared measurements were made to determine total nonvolatile hydrocarbons in a manner similar to that described by Brown et al (1973). Four liters of seawater were extracted with spectrograde CCl^; the extract was concentrated to 1 ml and treated with activated F l o r i s i l to remove nonhydrocarbon material. Measurements were made on a Perkin-Elmer infrared spectrophotometer (Model 467) at 2930 cm which gave a measure of the a l i -phatic hydrocarbons present. The response was compared with fuel o i l standards to give a measure of total hydrocarbons. Discussion of Analytical Methods One of the purposes of this investigation was to test the validity of the most common analytical methods for determining hydrocarbons under con-trolled conditions. The fluorescent and gas chromatographic methods were scrutinized to determine their reliability and to identify weaknesses and pro-blems that occur in their practical application. Fluorescent Method: 1) Sampling: Gordon et al (1974-) found that open Knudsen samplers were not suitable for hydrocarbon sampling, since they got the same fluorescent values whether or not they tripped the bottles. Undoubtedly some hydrocarbon 202 material adsorbed on the walls of the containers when they passed through the surface film. The remaining fluorescence probably was due to plasticizers extracted from the bottles when they were rinsed with solvent. In this exper-iment an ordinary 5 liter Niskin bottle was used to obtain samples as per Gordon et al, but the bottle was not rinsed with solvent after obtaining a sample. The data indicates that no significant contamination occurred during sampling. This can be seen from the background samples, which are uniformly low, and from the surface samples taken after the second spike (see Figure 46). The surface samples are a l l low in hydrocarbons, while deeper samples have much higher values. This result would not be possible if contamination of the bottle was occurring as i t passed through the surface film. Two factors pro-bably contributed to the successful use of the Niskin sampler in this experi-ment: the levels of hydrocarbons tended to be high compared to those being measured by Gordon et al, due to the spike of o i l added; and the sampler was not rinsed with solvent, which minimized contamination by plasticizers in the P.V.C. plastic. 2) Temperature of extraction: some preliminary observations indi-cated that the temperature of extraction influenced the extraction efficiency. Although this relationship was not rigorously investigated, a l l samples were extracted at 5°C to eliminate this variable and improve the precision of the results. 3) Formation of emulsions: the extraction of samples of CEPEX water resulted in the formation of a water-in-solvent emulsion which would not separ-ate despite prolonged standing in a separatory funnel. These emulsions apparently result from natural emulsifiers which are present in the water column in biologically productive areas (the effect does not occur in off-shore samples). A glass wool plug was placed in the spout of the separatory funnel to physically break the emulsion. Some water was s t i l l present in the eluted dichloromethane, and this was merely left in the roundbottom flask after 203 rotoevaporation, where apparently i t did not i n t e r f e r e with the analyses. 4) Use of heat gun: water from the emulsion described above was l e f t i n the roundbottom f l a s k after rotoevaporation, together with the residue of the extracted material. This water was driven off with a heat gun u n t i l i t was found that the heat gun had a d r a s t i c effect on the fluorescent material. 90 seconds exposure to the heat gun reduced the fluorescence to 2% of i t s o r i g i n a l value. The use of the heat gun was discontinued, a l l the analyses were repeated, and water was allowed to remain i n the roundbottom f l a s k after rotoevaporation. Apparently i t did not i n t e r f e r e with analyses. Time of Exposure Fluorescence to heat gun (ng/1 chrysene equiv.) 0 561 45 sec 101 90 sec 13 5) Solvents: Low blanks for dichloromethane (residue of 150 ml) were consistently d i f f i c u l t to obtain. Repeated d i s t i l l a t i o n often resulted i n increasing contamination of the solvent with fluorescing material. Event-u a l l y , Caledon g l a s s - d i s t i l l e d solvents were purchased, and these gave low blanks without requiring d i s t i l l a t i o n . 6) Glassware: glassware was cleaned i n chromic acid, rinsed with d i s t i l l e d water, and washed with high grade acetone. Before use, i t was rinsed once with spectrograde hexane. Leaving out any of these steps resulted i n con-tamination problems. The ground-glass area was the prime source of contamina-ti o n . 7) Syringe carryover: a 1 ml syringe was used to i n j e c t into a high-pressure l i q u i d chromatograph. Contamination from a syringe previously used on a concentrated sample can carry over for up to 10 i n j e c t i o n s . A single syringe contamination resulted i n erroneously high values for 5 CEPEX samples, and possible contamination of s i x more, a l l of which had to be repeated. Great care must be taken i n syringe handling and cleaning. 204 8) Linearity of response: during these analyses a great deal of information was lost because of a non-linearity in the slide wire driving the recorder pen. As a result of this problem, a careful check of the linearity of the instrumental response was made. Figure 39 shows the response as a function of the chrysene concentration injected: the response was very linear on the two sensitivities checked. Peak area, but not peak heights, were con-served when switching from one range to the other. FIGURE 39: Linearity of Fluorescence Response for Determination of Hydrocarbon Concentrations BjCIOtM) 7XC0(»n»l 8 10 15 CONCENTRATION (Pfl^l) Solid lines indicate peak heights, and dashed lines indicate peak areas. Two ranges were checked for linearity (8 x 10 is twice as sensitive as 7 x 10). 205 9) Precision of r e s u l t s : Figure 39 implies good precision of response, but over periods of time longer than a few hours the precision of the fluorescence method was not p a r t i c u l a r l y good. The standard concentration of chrysene used to ca l i b r a t e the CEPEX measurements gave disc integrator response that varied between 14.3 and 17.8 over the nine days i n which the measurements were performed. The largest v a r i a t i o n for a single day was almost as large: 14.9 to 17.8. The mean and standard deviation for 10 determinations over 9 days was 16.2 + 1.2. Some of the uncertainty may have resulted from variations i n the volume injected by the syringe, but the most l i k e l y source of v a r i a t i o n i s the l i g h t source. I t i s possible that a double beam i n s t r u -ment would be required to improve the precision of the r e s u l t s . 10) Column performance: from time to time the column interacted with samples i n such a manner that delayed peaks were detected 5 to 15 minutes after the main fluorescent peak. The area of the secondary peaks was sometimes substantial, and interfered with subsequent analyses. The secondary peaks complicate the analyses, and rai s e the question whether or not the f i r s t peak i s the only one which should be quantified. Further work i s required to c l a r i f y t h i s matter. 11) Chrysene standard: a l l measurements of o i l i n the CEPEX bags were made i n terms of chrysene equivalents. Chrysene was used as a standard because i t was i n general use at the laboratory as a standard for a l l oceanic determinations of hydrocarbons. I t was o r i g i n a l l y chosen as a standard for several reasons: a pure organic compound - available i n unlimited supply and exhibiting an unaltering fluorescent spectrum - was desirable to f a c i l i t a t e comparisons of o i l concentrations. Since heavy o i l s generally show a f l u o r -escence excitation maximum i n the region 290-330 nm and an emission maximum i n the region 360-400 nm, the standard was chosen to have a si m i l a r response. Chrysene fluoresces i n the right range and i s readily available at low cost 206 in high purity, so i t was chosen as a standard. 1 ng/1 chrysene is the fluorescent equivalent of 118 + 3 ng/1 of #2 fuel o i l . 12) Simultaneous U.V. detection: the elutant from the liquid chromatograph passed through an ultraviolet as well as a fluorescent detector. The ultraviolet response was monitored, but i t was difficult to get good blanks for both the U.V. and the fluorescent detectors. The results were not consistent and are not presented here. However, with some development, both detectors could be used simultaneously. Gas Chromatographic Analyses: The problems with the gas chromatographic analyses were never fully resolved, and the results obtained were without pattern or significance. The reasons for this dismal performance are discussed below. 1) Extraction: in order to perform extractions on large quantities of water without using correspondingly large concentrations of solvent, a con-tinuous extraction apparatus was constructed similar to that described by Werner and Waldichuk, 1962. The apparatus required about 300 ml of solvent which was refluxed through a steady flow of sample water (counter current extraction). Although the published efficiencies of the extractor were quite high (44% - 75% depending on conditions) i t was found that the extraction efficiencies for the particular parameters used in this experiment were very low - about 5%. This low extraction efficiency, which was not noticed until most of the analyses had been performed, presumably was a major factor in the poor results obtained. 2) Solvent purity: 300 ml of pentane were used in the extractions. The chromatogram of an undistilled pentane blank is shown in Figure 40. A large contaminating peak eluting at 252°C is evident (labelled 'S'). Di s t i l -lation of the pentane did not improve its purity, but instead increased the contamination, adding several more peaks and increasing the size of the 'S' contaminant. Distillation was abandoned, and undistilled pentane was used 207 in the extractions. The ' S' peak was removed by the silica gel column (see Figure 4Z) indicating that i t was not a hydrocarbon. FIGURE 40: Effect of Distillation on Solvent Blanks Pentane blank (residue of 300 ml): a) prior to distillation i S •I b) after distillation it 3) Distilled water blank: using the extraction apparatus to extract distilled water gave the chromatogram in Figure 41. The solvent peak 'S' is again apparent, as well as two additional peaks. One was apparently present in the distilled water, while the other (labelled 'R') was a contaminant either from the atmosphere or the apparatus, and appeared in a l l extracted samples. 208 FIGURE 41: Distilled Water Blank 4) Effect of column pretreatment: Figure 42 shows the effect of first injecting the sample into the high-pressure liquid chromagraph (silica gel column) as opposed to direct injection into the gas chromatograph. The column removes the contaminating peaks R and S, and enhances the aliphatics relative to the envelope. FIGURE 42: Effect of a Preparative Silica Gel Column on Gas Chromatographic Analyses  CEPEX carboy sample #4B: a) without silica gel column preparative step b) with silica gel col umn 209 5) R e p l i c a t i o n of analyses: Figure 43 shows dup l i c a t e analyses of a CEPEX water sample. Despite the most c a r e f u l a t t e n t i o n to p o s s i b l e sources of contamination, the chromatograms are w i l d l y d i f f e r e n t . Use of the prepara-t i v e HPLC step reduced the v a r i a t i o n s by removing some contaminants, but nevertheless there was never, i n eleven sets of dup l i c a t e analyses, a c l e a r s i m i l a r i t y between chromatograms. The reasons f o r these rather spectacular v a r i a t i o n s i n r e s u l t s are not understood. FIGURE 43: R e p l i c a t i o n of Gas Chromatographic Analyses of Water Samples a) Subsample A, CEPEX carboy #2. R S b) Subsample B, CEPEX carboy #2. 5 210 6) Contamination: the c r u d e s t i n s u l t came from the f i n a l sample analysed, which was from the control enclosure F. This sample, which was sup-posed to be hydrocarbon-free, gave a clearer alkane spectrum than any of the samples taken from the polluted enclosure. The source of th i s contamination, which found i t s way to the sample despite the most scrupulous clean-room conditions, i s indeed perplexing. FIGURE 44: A Contaminated Sample from the Control Enclosure This experience with gas chromatographic analyses emphasizes the d i f f i c u l t i e s of analysing water samples. Some of the problems undoubtedly re s u l t from the extraction apparatus, which was not very successful. The very irre g u l a r nature of the r e s u l t s , and the constant contamination problems cannot be accounted f o r purely by the extraction apparatus, however. Some possible contributing factors are: the sampling procedure, which involved pumping the water to the surface using a diaphragm pump; rotoevaporation, which may have caused varying losses of l i g h t e r components; and contamination from the atmos-phere during the continuous extraction procedure. Beyond these three explana-tions, i t i s d i f f i c u l t to see how so much contamination and v a r i a b i l i t y occurred, since a l l glassware was thoroughly cleaned, and a l l manipulations and transfers were c a r e f u l l y performed i n a 'clean room'. 211 Results A gas chromatogram of the #2 fuel o i l used in the experiment is given in Figure 45, together with a chromatogram of the seawater extract of the o i l which was added to CEPEX enclosure. The results of the fluorescent analyses are presented in Figure 46, and in Table 30. 212 FIGURE 45: Gas Chromatograms of //2 Fuel Oil and its Saturated Seawater Extract #2 Fuel o i l : a L3 _15. Oil-saturated seawater: MN = methylnapthalene. Identification of peaks is based on retention times and is tentative. Note enrichment of napthalene compounds relative to paraffins in the seawater extract. FIGURE 46: Fluorescence Results for CEPEX Hydrocarbon Experiment a) First addition of #2 fuel o i l : (all measurements at 7 m) 600 500 > 4 0 0 •*3oo 2oo loo TIME (days) b) Second addition of #2 fuel o i l : 2-*xH £2oooJ < I 6 0 0 ' B00A I m 7 m'. 13 m TIME (days) 214 TABLE 30: Results of Fluorescent Determinations of Hydrocarbons i n the CEPEX Enclosures F i r s t Experiment Location Depth Time after Contamination Value ! (ng/l chrysene G 7 m before 15 min l i hr 3i hr 7 hr 15£hr 25 hr 80.5 586 452 418 356, 339 198, 306 173 4 days 117 G 13 m 25 hr 29.7 outside CEE 7 m 5 days 17.7 Second Experiment Location Depth Time af t e r Contamination Value | (ng/l chrysene G 1 m 4 hr 283 21 hr 114 36 hr 115 55 hr 119 3 days 3 hrs 120 7 days 5 hrs 70 G 7 m before 117 0 hr 1898 4 hr 1990 11 hr 2680 21 hr 1325} 1708 36 hr 1375 55 hr 1213 5 days 684, 737; 561 7 days, 5 hr 550, 476 215 TABLE 30 continued: Second Experiment (continued) Location control outside Depth 13 m 7 m 1 m 7 m Time after Contamination 4 hr 21 hr 36 hr 55 hr 3 days 3 hr 4 hr 7 days 5 hr 7 days 5 hr Value I (ng/l chrysene equiv.) 246 1710 1115 1798 802 72 41 33 #2 Fuel Oil Equivalent Determination # Conversion factor for #2 fuel o i l in hexane 1 118.6 disc response chrysene 2 115.5 disc response fuel o i l 11 3 113.7 11 4 120.8 11 Average: Chrysene fluoresces 118 + 3 times as much as the same concentration of fuel o i l , when both are dissolved in hexane. 216 Discussion of Results The chromatograms i n Figure 45 show a pronounced enrichment of aromatics relative to alkanes i n the water extracts of the #2 fuel o i l . In particular, the ratio of methylnapthalenes to C-13 and C-14 alkanes increased from 0.80 i n the fuel o i l to 3»5 i n the water-soluble fraction, an increase of 440$-(this aromatic enrichment i n the soluble fraction has been reported by others — see Chapter 3). The gas chromatographic analyses of CEPEX water samples were too unreliable to provide further information. The background level of fluorescence i n Saanich Inlet was 49 + 27 ng/l chrysene equivalents, which compares with 18 + 6 ng/l i n the open Pacific (see Table 28). The spike of o i l clearly shows i n Figure 46: the maximum value obtained after the f i r s t addition was 586 ng/l chrysene equivalents, which cor-responds to 69 ug/l of #2 fuel o i l (the infrared method indicated a t o t a l of 50 ug/l of fuel o i l ) . The hydrocarbons disappeared exponential1y, and the curve can be parameterized by the following relation: y = 452 e""*^^ where y i s the fluorescence response i n ng/l above background, and t i s the time after contamination in hours. The coefficient of determination for this curve f i t i s 0-83 . The ' h a l f - l i f e ' of the hydrocarbon spike was about 13 hours. For the second addition of hydrocarbons, ethanol was used to increase the s o l u b i l i t y of the o i l , so that the added spike was about 100 times as concentrated as the f i r s t spike. The addition was made entirely at 8 m using a diffusing ring. The maximum concentration, 2680 ng/l chrysene equivalents, was not observed at 7 m u n t i l 11 hours after addition, presumably because of the delay i n the o i l niixlng upwards- (on the basis of equal distribution of the added o i l throughout the water column of the enclosure, a peak value of 1370 ng/l i s expected). Again the disappearance of the hydrocarbons was approximately exponential, following the relation: 217 y = 2050 e (symbols as before) The coefficient of determination for this curve f i t was 0.90. The 'half-life' of the peak was 63 hours. The consistently low concentrations of hydrocarbons at 1 m after the second addition pose an interesting question: since a l l the o i l was added at 8 m, i t is possible that no o i l was advected or diffused into the uppermost waters of the enclosure; alternatively, o i l may have been evaporating as quickly as i t reached the surface waters. On the basis of this data alone, i t is not possible to distinguish between the two possibilities. However, using the model of gas exchange between ocean and atmosphere developed by Liss and Slater (L974) i t is possible to get an estimate of the residence times of dissolved hydrocarbons (see Appendix C for f u l l discussion). The half lives of poly-aromatic fluorescing compounds at 1 m depth at the temperature of the water in the bags (about 20°C) would be about 1 day. (See Table 34 in Appendix C). This rate of exchange with the atmosphere is probably sufficient to keep the hydrocarbons which advect to the surface of the bag at a consistently low level. The half l i f e increases linearly with depth (see Appendix C) so at 7 m the half l i f e is about 7 days. Since the half l i f e of the hydrocarbon spike was 3 days, other processes must have contributed to the removal of the o i l . The hydro-carbon levels at 13 m remained low for least five hours after addition of the o i l , but after 21 hours, had increased above the levels at 7 m. This result suggests that sedimentation of hydrocarbons was occurring. Ultraviolet exam-ination of the sediment by Dr. R. Lee (see Lee et al, 1975) detected milligram quantities of naphthalenes after 4 days, whereas no naphthalenes were detected in the control bag sediment, thereby providing clear evidence that significant rates of sedimentation were occurring. Fluorescent analyses of the sediment gave high values in both the control and the hydrocarbon enclosures, so that the 218 degree of sedimentation of hydrocarbons could not be ascertained effectively in this manner. To determine the extent of microbial activity, water samples were taken, and microbial degradation rates were measured using radiolabeled hydro-carbons. (This work was performed by Dr. Lee - see acknowledgements). After the addition of oil,' degradation rates increased dramatically for most of the lighter hydrocarbons. For example, the napthalene degradation rate jumped from 0.1 to 2.5 ug/l/day. For the large polyaromatic compounds the change was not so pronounced. Fluorene and benzopyrene were not degraded before addition of the o i l ; after additon, degradation of benzopyrene, but not fluorene, was detectable. The chrysene degradation rates were not determined, but probably were also low. Microbial degradation, therefore, was important in the overall removal of the hydrocarbons, but its importance in the degradation of the polyaromatic compounds detected by the fluorescence method is less clear. It is possible that larger organisms *iuch as zooplankton may have played a role in the degradation of these compounds (Lee, 1975)* Conclusions 1. High pressure liquid chromatography combined with a fluores-cence detecter provides a reliable method of determining the concentrations of fluorescing hydrocarbons in seawater as long as stringent precautions are taken to guard against contamination. 2. Although there is some ambiguity in the data, i t appears that exchange with the atmosphere was the dominant process in the removal of dissolved hydrocarbons from the uppermost meter or two of the water column, while in the deeper water microbial degradation and sedimentation were the most important processes. 3. The disappearance of the o i l approximately followed an exponen-t i a l decay curve: the half-life for a large dissolved o i l spike was about 3 days (less for a smaller spike) so that 95% removal occurred within 2 weeks. SUMMARY OF FINDINGS 220 Controlled Weathering Experiment: 1. Photo-oxidation i s not an e f f e c t i v e weathering mechanism for o i l i n a moderately thick (3 mm) layer. 2. The rate of evaporation of v o l a t i l e components from a layer of o i l i s very strongly dependent on the surface/volume r a t i o , varying over at least 3 orders of magnitude from a thin f i l m to a 3 mm layer. Apparently, reduced surface area may result i n less absolute loss no matter how long the o i l i s exposed. 3. The effect of evaporation alone i s not s u f f i c i e n t to produce tar lumps and cause sinking of crude o i l - microbial degradation i s required. Pelagic Petroleum Residues: 4. On the basis of 2092 surface tows between 1967 and 1975 the following conclusions were reached about the d i s t r i b u t i o n of tar i n the P a c i f i c : a) Petroleum residues are not a s i g n i f i c a n t pollutant i n the surface waters of the South P a c i f i c . b) In the Northeast P a c i f i c occasional contamination of ^ surface tows occurs (average concentration i s 0.03 mg/m ). c) The Northwest P a c i f i c i s the most contaminated area, p a r t i c u l a r l y i n the Kuroshio current system between 25° and 40°N. The average concentration i n t h i s area i s 2.1 mg/m2, which represents a standing stock of 25,000 metric tons of t a r . 5. P l a s t i c i s a widespread contaminant on the North P a c i f i c Ocean, but generally i n lower quantities than t a r . I t usually occurs as round, colourless p e l l e t s weighing 20-50 mg each. 6. The Beaufort Sea i n the A r c t i c Ocean i s not contaminated by tar. P l a s t i c , however, i s a common contaminant on the beaches. 7. The d i s t r i b u t i o n of the tar i n contaminated areas i s patchy, so that r e p l i c a t e tows catch widely varying quantities of tar which approxi-221 mately follow a log normal d is t r ibut ion . This patchiness cannot be explained on the basis of windrows, and probably i s a result of the tar gradually spread-ing out from point sources. The tar d istr ibut ion may be best represented mathematically by Newmann's contagious d is t r ibu t ion . 8. Most tar part ic les were in the 1-5 mm range, but most of the tar mass was in part ic les in the 5-10 mm range. The largest tar lump was 5 cm in diameter and weighed 34 g. 9. The average water content of the tar was 22% by weight, which i s considerably less than the amount of water in a fresh water - in -o i l emulsion (80%). 10. Tar samples stored for a year and a hal f by refr igerat ion or i n formalin did not show any detectable change i n composition. 11. Surface tows and beach surveys made in l o c a l B r i t i s h Columbia waters in an area of heavy urban and industr ia l development (including three o i l ref ineries) detected no petroleum residues, implying that the source of tar is not from run-off or refinery o u t f a l l s . ! - • High iron concentrations of greater than 1 ppt were found in 77% of the 104 tar samples analysed (iron in crude o i l does not exceed 0.1 ppt) . .N ickel concentrations, however, were not detectably above those in crude o i l , so general metal enrichment did not occur. The anomalously high levels of i ron strongly imply an anthropogenic source of the tar . 13. Gas chromatographic analyses provided a second and more pre-cise indication of the source of the tar . 88% of the 82 samples analysed con-tained long-chain, waxy paraffins of higher carbon number than C-25 in much greater abundance than they are normally found in crude o i l . These long-chain paraffins are typical of the sludge discharged by tankers when they clean their tanks after carrying crude o i l . This tanker sludge i s probably the source of most of the pelagic tar in the P a c i f i c . 222 14. The chemical analyses, combined with the d i s t r i b u t i o n pattern of the t a r , imply that most of the pelagic tar contamination i n the P a c i f i c originates from tankers on the very large Middle East to Japan tanker route, then becomes entrained i n the Kuroshio current south of Japan and creates a plume of contamination which extends downstream for 7000 kilometers across the P a c i f i c . 15. The standing stock of tar i n the Northwest P a c i f i c (25,000 metric tons)•represents a loss Of only about 0.01% of the o i l carried on the Japanese tanker route. However, because of the vast quantities being trans-ported and the persistance of the tarry f r a c t i o n , even a very small percentage loss results i n s i g n i f i c a n t contamination of the surface waters. 16- Photo-oxidation does not detectably contribute to the degrada-ti o n of tar. The role of d i s s o l u t i o n i s uncertain, but from t h e o r e t i c a l con-siderations i s presumed to be small. 17. Evaporation removes compounds up to the v o l a t i l i t y of pentade-cane (C-15) from the t a r : 73% of the 82 samples analysed had l o s t a l l n-alkanes up to C-15. Above C-15 the evaporative losses become very slow and the process i s usually overtaken by microbial attack. 18. At l e a s t 33% of the tar samples analysed by gas chromatography showed clear evidence of microbial degradation. 19. Small p a r t i c l e s of tar did not show any tendency to be further affected by evaporation or microbial attack than larger lumps. No gradient of l i g h t e r compounds between the inside and outside of a large tar lump could be detected, in d i c a t i n g that evaporation i s not d i f f u s i o n - l i m i t e d . 20. Both evaporation and microbial degradation increase the density of the tar p a r t i c l e s , and this e f f e c t combined with the weight of the fouling community that develops, re s u l t s i n the eventual sinking of the tar into the depths of the ocean. 223 21. Tar particles provide the biota of the surface of the ocean with a substrate on which they can live and reproduce. 22. Tar occurs as a pollutant on a very large portion of the world's beaches, including nearly a l l of the popular seaside resort areas. The pre-sence of the tar severely reduces the recreational and esthetic value of sandy beaches. Intertidal Oil: 23. Microbial degradation was responsible for the chemical weathering of the spilt o i l at Reserved Bay. Evaporation played only a minor role; photo-oxidation and dissolution did not appear to have any effect. 24. Microbial attack took approximately 1 year to complete the degra-dation of the paraffins in the spilled o i l , leaving an asphalt-like residue on the stones of the beach. The asphaltic residue was apparently more susceptible to physical weathering than the original o i l . 25. The combined effects of chemical and physical weathering removed about 95% of the spilled o i l from the cove over the period of one year. Benthic Oil: 26. Heavily-oiled samples should be preserved in formalin i f they are to be stored for any length of time prior to analysis, since the formalin not only prevents bacterial alteration, but also eliminates evaporative losses which can occur i f the samples are stored by refrigeration. 224 27. The degradation of the benthic crude o i l resulted almost en-t i r e l y from microbial action. Evaporation had no opportunity to act; d i s s o l u t i o n was i n e f f e c t i v e ; and photo-oxidation was not possible because of the low energy and i n t e n s i t y of the l i g h t reaching the sediment. 28. The benthic petroleum samples were slow to degrade: the o i l remained unchanged i n chemical composition for at least s i x months. £ven af t e r 16 months the p a r a f f i n s , which are the f r a c t i o n most susceptible to attack, were only p a r t i a l l y degraded. 29. The pattern of degradation appeared to consist of an i n i t i a l delay while b a c t e r i c i d a l components were dealt with, followed by microbial degradation of the reamining o i l " a t roughly the same rate as i n the i n t e r t i d a l experiment - one year to remove the p a r a f f i n components. O i l i n the Water Column: 30. High pressure l i q u i d chromatography combined with a fluorescence detector provides a r e l i a b l e method of determining the concen-t r a t i o n of the fluorescing hydrocarbon compounds i n seawater, provided stringent precautions are taken to guard against contamination. 31. I t appears that exchange with the atmosphere was the dominant process i n the removal of fluorescing hydrocarbons from the uppermost meter or two of the water column, while i n the deeper water (below 7 m) microbial degradation and sedimentation were the most important processes. 32. The disappearance of the o i l approximately followed an ex-ponential decay curve: the h a l f - l i f e for a large dissolved o i l spike was about 3 days (less for a smaller spike) so that 95% removal occurred within 2 weeks. LEAVES 225 AND 226 OMITTED IN PAGE NUMBERING. 227 CONCLUSIONS The research presented i n this thesis provides some f i r s t order approximations of the rate at which, and the mechanisms by which, petroleum degrades i n various marine environments under natural conditions. For the pelagic environment, the study of floating petroleum residues i n the Pacific i s revealing because, i n contrast, to the Atlantic, there i s only one plausible source for most of the t a r . This considerably simplifies the situation. Because of the very large size of the Pacific, proportionately less of the tar ends up on beaches, and therefore the evidence of microbial attack and eventual siiiking i s clearer.than i n other areas. The rate of rnicrobial attack was not directly determined, but from the distribution pattern i t i s evident that some of the tar must remain afloat f o r periods on the order of one to two years. Thus the mechanism by which the pelagic environ-ment deals with petroleum residues i s a rather slow process, so that even a small percentage loss of petroleum cargoes results i n significant and widespread contamination of the surface waters. The study of o i l i n the i n t e r t i d a l environment was a unique opportunity to observe the degradation of a reasonably large (by experimental standards) quantity of o i l under natural conditions. The opportunity was unusual since, i n most areas, public use of the beach areas requires immediate clean-up of o i l s p i l l s . At Reserved Bay the area i s su f f i c i e n t l y uninhabited that the o i l remained undisturbed by clean-up crews and the general public. The samples from the bay show very clearly the advance of microbial N grazing' of the paraffin compounds i n the fuel o i l . The combined action of the microbes and abrasive weathering removed 95$ of the o i l on the beach over a period of a year, leaving an unobtrusive and essentially inert residue of asphalt on the stones of the 228 beach. Even though there are a great many variables to be considered, this f i r s t order . measurement of natural rate of o i l removal is useful in determimng the extent of clean-up that is required after an o i l s p i l l . The measurements in the benthic environment of the rate and means of the degradation of petroleum are the f i r s t measurements of any sort to be published. The results are important primarily in assessing the propriety ' of using sinking agents to treat o i l spill s . The experiment shows that the degradation on the bottom, even under good conditions for microbial growth, is very slow to begin, with virtually no change in the composition of the o i l occurring oyer a 6 month period .. Such a slow commencement of the degradation process, i f i t is of general occurrence, would certainly weigh against the use of sinking agents. The study of o i l in the water column, while not as definitive a study as was hoped because of instrument difficulties and contamination problems, s t i l l did provide some indication of the rate at which, and mechanisms by which, hydrocarbons are removed from the water column. The relatively short l i f e of a dissolved hydrocarbon spike in the water - a matter of one to two weeks for even the most persistent of the dissolved compounds - i s in part a reflection of the very low levels at which hydrocarbons are soluble, and their preference to leave the water phase in favor of the atmosphere or adsoption on detritus. 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The s t a t e d conversions are f o r o i l of s p e c i f i c g r a v i t y 0.86 . 1 b a r r e l = 42 U.S. g a l l o n s = 35 I m p e r i a l g a l l o n s = 159 l i t e r s 1 n a u t i c a l m i l e = 1854*4 m 1 knot = 0.514 m/sec 1 mg/m = 5«7 l b / s q . m i l e = 0.14 ounces/acre U s e f u l Q u a n t i t i e s P r i s t a n e and phytane r a t i o s i n v a r i o u s crude o i l s : Crude oil pristane j phytane n-heptadecane/pristane n-heptadecanejbackgr. N Kuwait 0-48 ± 001 5-75 4- 007 2-87 006 6 Boscan 0-53 ± 003 1-18 4- 002 0-80 007 5 West Texas (high sulphur) 0-88 ± 001 1-65 ± 003 1-76 ± 002 4 La Rosa 0-89 ± 002 1-44 _1_ 003 090 ± 002 5 Wilmington 1-37 ± 002 0-31 4_ 001 0-34 4- 002 5 East Texas 1-41 ± 002 1-61 = 004 3-80 4- 006 7 South Louisiana 1-54 ± 004 1-48 004 2-13 ± 006 6 Lagunillas 1-54 ± 006 0-81 ± 002 0-28 ± 002 10 N = number of gas chromatograms. (from Ehrhardt and Blumer, 1972) APPENDIX A continued: P r i s t a n e and phytane i n v a r i o u s crude o i l s (% by volume): n-C 1 7 Pristane n-Cis Phytane 0.20 0.40 0.20 0.60 0.20 0.55 0.15 0.10 0.50 0.15 0.45 0.55 0.40 1.10 0.45 0.75 0.30 0.05 0.10 0.05 0.10 0.35 0.10 0.20 0.50 0.35 0.50 0.35 0.45 0.50 0.55 0.25 0.85 0.40 0.55 0.20 0.50 0.45 0.35 0.60 0.55 0.55 0.25 0.40 0.40 0.30 0.50 0.75 0.45 0.10 0.15 0.25 0.15 0.20 AVERAGE 0 .58+.35 0.32+.18 0.47+.18 0.25+.12 (from M a r t i n et a l , 1963) 253 APPENDIX B: BIOLOGICAL EFFECTS OF OIL POLLUTANTS The chemical complexity of o i l and the b i o l o g i c a l complexity of mar-ine ecosystems combine to make the study of o i l p o l l u t i o n e f f e c t s something of an experimental j u n g l e . O i l composition, as has already been d i s c u s s e d , v a r i e s w i d e l y , both w i t h i n the crude o i l s and between types of r e f i n e d pro-ducts. Bioassay experiments, the most s t r a i g h t f o r w a r d way of s t u d y i n g b i o -l o g i c a l e f f e c t s , are i n f l u e n c e d by d i f f e r e n c e s between i n d i v i d u a l s i n the same spec i e s , seasonal c y c l e s of organisms, l i f e s t a g e , and d i f f e r e n c e s between species. Furthermore, bioassay techniques are not w e l l standardized so that r e s u l t s may vary w i d e l y from one researcher to another. I n v e s t i g a t i o n s i n t o the more e l u s i v e s u b - l e t h a l e f f e c t s must a l s o account f o r n a r c o t i c , c a r c i n o g e n i c , and hormonal mechanisms. E c o l o g i c a l s t u d i e s must deal w i t h even more complex f a c t o r s , such as r e l a t i v e e f f e c t s of o i l on competing s p e c i e s , e f f e c t s of food chain dynamics, and s t i m u l a t i o n as w e l l as i n h i b i t i o n of p r o d u c t i v i t y . Research i n t o the e f f e c t s of petroleum began i n the nineteenth cen-tury (Macadam, 1866), became more common i n the 1920's, and blossomed a f t e r the Torrey Canyon o i l s p i l l i n 1967. Much of the e a r l i e r l i t e r a t u r e c o n s i s t e d of bioassays w i t h poor determination of c o n c e n t r a t i o n , s t a t e ( d i s s o l v e d , emul-s i o n , or s l i c k ) , and composition of the o i l used. The i n v e s t i g a t i o n s have become i n c r e a s i n g l y s o p h i s t i c a t e d , and now deal w i t h complex s u b l e t h a l e f f e c t s such as i n t e r f e r e n c e w i t h pheromone communication at concentrations i n the parts per b i l l i o n (ppb) range. I t i s not the purpose of t h i s review to summarize the very l a r g e amount of i n f o r m a t i o n a v a i l a b l e , but r a t h e r to present some g e n e r a l i z a t i o n s which have been reached as a r e s u l t of the accumulation of t h i s broad spectrum of i n f o r m a t i o n . The Relative Toxicities of Petroleum Compounds 254 The following generalizations have been made specifically for plants (see summary in Baker, 1971), but the same trends should also apply to animals because the mechanisms of toxicity are similar at the cellular level. 1) Toxicity increases'with unsaturation, increasing from paraffins to naphthenes and olefins to aromatics (Havis, 1950). For example, 12-carbon paraffins are nearly non-toxic, 12-carbon olefins are quite toxic, and 12-carbon aromatics are more toxic (van Overbeek and Blondeau, 1954). Similarly, toxicity of vapours to barley and carrot increases along the series hexane, hexene, cyclohexane, cyloxhexene, benzene (Currier and Peoples, 1954). 2) Within each class of hydrocarbons, the smaller molecules are more toxic than the larger. For example, within the paraffins, octane (C-8) and decane (C-10) are very toxic, while dodecane (C-12) and higher paraffins are nearly non-toxic (van Overbeek and Blondeau, 1954). As a consequence, refined products which tend to concentrate the lighter portions of crude o i l (gasoline, light fuel oils) tend to be more toxic than crude o i l . Conversely, petroleum products consisting of the residual heavy components of crude o i l (fuel o i l #5 and 6) are generally less toxic than crude o i l ; and weathered crude, which has lost its lighter, more volatile components, is generally less toxic than fresh crude o i l . There are exceptions. Specifically, aromatics apparently increase in toxicity along the series benzene, toluene, xylene, trimethylbenzene, apparently because the increase in methyl groups promotes cell penetration (Currier, 1951). However, beyond this point increasing molecular size of aromatics results in decreased toxicity. 3) Within crude oils there is a correlation between the toxicity of the o i l and the concentration of monocyclic aromatics that i t contains (Ottway, 1971). Other compounds which have-been implicated in the toxicity of crude o i l are: acids and phenols, sulphur compounds (thiols, sulphides and thio-phenes), and the carcinogenic polynuclear aromatic hydrocarbons (3,4-benz-pyrene, 1,2-benzanthracene, chrysene, fluorene, phenanthrene, and dibenz-thiophene). The concentrations of these toxic compounds i n crude o i l are given i n Table 31. TABLE 31: Percentage of Toxic Compounds i n Crude O i l s (1) Low molecular weight aromatics (2) Phenols (3) A c i d s (4) Sulphur compounds (5) P o l y n u c l e a r aromatic hydrocarbons 0 0 0 0 0 - 0 . 1 % - 2% - 0.1% - 4 0 % - 8% 256 Effects at the C e l l u l a r Level The f i r s t work on the effect of petroleum compounds on c e l l s was done as a part of investigations into using o i l s as herbicides, fungicides, and i n s e c t i c i d e s . These investigations established that, i n acute o i l t o x i -c i t y , increased permeability of the plasma membrane i s involved (van Overbeek and Blondeau, 1954). Apparently, hydrocarbon molecules of lower molecular weight are soluble i n the membrane lipoproteins and cause swelling and d i s -ruption of the membrane. Increased permeability may resu l t i n increased up-take of water, or, i n the extreme, may allow organic molecules to leak out of c e l l , causing collapse and death. The larger the size of the hydrocarbon mole-cules, the slower i s the penetration into the membrane (van Overbeek and Blondeau, 1954). Because of the wide variety of compounds i n petroleum, i t i s not surprising that membrane disruption i s not the only pathological e f f e c t . Man-well and Baker (1967) have demonstrated that crude o i l interferes with the a c t i v i t y of enzyme systems from a wide variety of marine plants and animals. Powell et a l (1970) observed hyperplasia i n an estuarine bryozoan attributable to coal tar derivatives. Uncontrolled growth i n o v i c e l l s apparently resulted from a carcinogen i n coal tar. Goldacre (1968) reviewed work on the natcotic effect of the lower molecular weight paraffins on various c e l l s , and suggested this was a result of interference with the c e l l membrane. He also speculated that hydrocarbon carcinogens cause permanent changes i n the c e l l membrane leading to a breakdown i n c e l l - c e l l communication and to cancer. Finnerty et a l (1973), using electron micrographs, have shown that i n c l u s i o n bodies or 'pools' of hydrocarbon are formed i n the cytoplasm of bacteria, yeast, and fungi grown on pure hydrocarbons. The bacteria also undergo morphological transformations, s p e c i f i c a l l y intracytoplasmic membrane synthesis and irregu-l a r formation of giant c e l l s . The reasons for these bizarre effects are not known. i In summary, the e f f e c t s of hydrocarbons on c e l l s are not w e l l understood, but most seem to be manifestations of interference with the membranes of the c e l l . 258 Effects at the Organism Level The l i t e r a t u r e dealing with the effects of o i l s on various organisms i s extensive. Papers deal with a l l forms of marine organisms from plankton to f i sh and b i r d s , and with a var ie ty of types of o i l s . However, the resu l t s sometimes are contradictory, and frequently are not comparable with one another because of d i f f e r i n g test condition's. No attempt to completely survey th is l i t e r a t u r e i s made here. L i te ra ture reviews are ava i l ab le : Nelson-Smith (1970), Nelson-Smith (1972), and Butler et a l (1974). Table 33 l i s t s some of the numerical resul ts which have been obtained by the authors reviewed i n these l i t e r a t u r e surveys, to give some idea of va r i e ty and extent of the re -search. This table has been updated with some more recent r e s u l t s , but does not purport to summarize a l l the information ava i l ab l e , much of which does not f i t in to a numerical or tabular format. The effects of o i l on organisms can be grouped under a few mechan-isms. Each of these w i l l be b r i e f l y reviewed. Smothering and Mechanical Damage: Damage from crude and res idua l o i l s i s p r imar i ly due to mechanical interference and smothering of organisms. Smothering mainly affects sedentary i n t e r t i d a l organisms such as macroalgae, barnacles, l impets , and mussels (see, for example, Chan, 1973 and 1975). B i rd s , p a r t i c u l a r l y d iv ing b i rds such as auks, suffer from mechanical damage. Their plumage i s o l e o p h i l i c , and, once contaminated, i t loses i t s i n su la t ive proper t ies . Death occurs p r imar i ly from exposure. The d iv ing bi rds have very low reproductive ra tes , wi th the resu l t that the i r populations have been severely depleted i n some areas of the world (Clark, 1968; Bourne, 1968). Poisoning: Dissolved and emulsified hydrocarbons are tox ic to a wide var ie ty of 259 marine organisms. Toxicity is a function of composition as has been dis-cussed: for example, high concentrations of low boiling aromatics are lethal to almost every species, whereas the high boiling paraffins are essentially non-toxic. Quantitative investigations of the poisonous levels of o i l have usually taken the form of bioassay experiments, many of which are summarized in Table 33. These bioassay experiments suffer from several chronic problems. Firstly, the experimental techniques frequently vary widely, making comparison of results difficult or impossible. Typical differences in experimental tech-nique involve the method of measuring the concentrations of the o i l , the method of exposing the organisms to the o i l (surface slick, emulsion, dissolved) and the environmental conditions of exposure (running sea water, static water, nutrients added, temperature, etc.). Secondly, the concentration of the o i l to which the organism is actually exposed is frequently not determined, and instead only the amount of o i l added is given. Thirdly, the o i l composition is frequently not characterized beyond 'crude' or 'no. 2 fuel o i l ' , so that the nature of the o i l components affecting the organisms is unknown. The reason for the last two problems is the difficulty of performing the necessary chemical analyses, which demand more s k i l l and equipment than the actual bio-assay experiment. Two papers which present bioassay results with thorough chemical analyses are Battelle (1973) and Anderson et al (1974). Within the limitations imposed by these problems, the various median tolerance limits given in Table 33 are indications of the levels at which various organisms are poisoned by petroleum compounds. In general, concentra-tions of greater than 100 ppm of dissolved or emulsified crude o i l are required for lethal effects, although the more sensitive species and lifestages (especially eggs) may be killed by concentrations of 10 ppm and (rarely) less. Most sublethal effects have been observed over a concentration range of 0.01 260 to 10 ppm. Refined products vary in toxicity roughly in accordance with their low-molecular weight aromatic content. For example, Anderson et al (1974) notes that, for six test species, dispersions of #2 fuel o i l ; which is rich in aromatics, were two orders of magnitude more toxic than dispersions of crude o i l . Sub-lethal Effects: The sub-lethal effect first observed was the narcotic effect of dissolved hydrocarbons. Organisms show markedly reduced activity levels, an effect which is usually reversible when the organism is placed in clean water (Marsland, 1933). Of greater concern, because i t occurs at much lower concentrations, is the interference of mineral hydrocarbons with chemical communication in the oceans. Hydrocarbons have been shown to interfere with chemoreception in crabs (Takahashi and Kittredge, 1973), with the feeding behavior of lobster (Atema and Stein, 1972), with chemotaxis in snails (Jacobson and Boylan, 1973), with bacterial chemoreception (Mitchell et al, 1972), and to cause avoidance behaviour in salmon (Rice, 1973). Marine animals make wide use of 'smell' or chemoreception for mating, feeding, and navigation (Lucas, 1947), so that the effect of adding the spectrum of hydrocarbons from crude oi l to the natural environment, even at ppb levels, could have widespread insidious effects. The presence of carcinogenic hydrocarbons in crude o i l has been verified by analysis, and by the unfortunate experience of machine operators who have suffered skin cancer from lubricating oils (Bingham et al, 1965). Most knowledge of the carcinogenic effects of various hydrocarbons has been gained from investigations of the health hazard of smoking. However, hyper-plasia, apparently caused by a dissolved petroleum carcinogen, has been observed in bryozoans growing near coal tar (Powell et al, 1970). The prime concern to anthropocentric scientists is human cancer through eating petroleum-contaminated sea foods. The threat is moderated by the wide occur-ence of the same carcinogenic hydrocarbons from natural sources, mainly natural fires (Zobell, 1971; Youngblood and Blumer, 1975), and by the fact that a good many species of animals and most aquatic bacterial populations can metabolize and degrade carginogenic hydrocarbons (Zobell, 1971). Many other sublethal effects on organisms are possible, such as those affecting reproduction, growth, metabolism, and behaviour. Generally, the findings are too few and scattered to be worth summarizing here. More complete reviews of sublethal effects are available in Nelson-Smith (1970b), Nelson-Smith (1972), and Butler et al (1974). E c o l o g i c a l E f f e c t s A l l the i n v e s t i g a t i o n s of o i l and organisms already discussed have implications at the e c o l o g i c a l , or community l e v e l . However, d i r e c t observa-tions of the e f f e c t s of o i l on communities are necessary to understand these implications and unravel the consequences f o r competing species that l i v e i n a complex and balanced web of l i f e . O i l damage to a species i s akin to a t r a f f i c accident at rush hour: i n ad d i t i o n to being t r a g i c i n i t s own r i g h t , i t has consequences that reverberate through the transportation system. Most knowledge of the broad scale e c o l o g i c a l e f f e c t s of o i l p o l l u -t i o n has come from experience with o i l s p i l l s . Table32 l i s t s f i v e of the major o i l s p i l l s with a quick sketch of the b i o l o g i c a l damage that r e s u l t e d from each. More complete discussions are a v a i l a b l e i n the o r i g i n a l references. O i l s p i l l studies usually s u f f e r from poor baseline information and lack of cont r o l s . / An exception i s the M i l f o r d Haven o i l port i n B r i t a i n (Cowell, 1971)/• Also, they generally deal with the i n t e r t i d a l and perhaps the benthic environment; the pelagic environment i s neglected, being too d i f f i c u l t to study i n an o i l s p i l l - s i t u a t i o n . The b i o l o g i c a l damage mentioned i n Table32 ranges from short-term e f f e c t s on a few species (Arrow) to long-term e f f e c t s on v i r t u a l l y a l l spe-cies ( F l o r i d a ) . The key v a r i a b l e i s the composition of the s p i l t o i l , a matter we have already discussed. The e c o l o g i c a l changes vary from k i l l , recruitment, and recovery (Santa Barbara); to the rather complex sequence of events that took place at the Tampico Maru s p i l l . Here there was an immediate severe k i l l of most species. Two or three months a f t e r the i n i t i a l damage, young kelp plants began to appear,and grew at an alarming r a t e , eventually choking the e n t i r e bay. The explosive growth was the r e s u l t of el i m i n a t i o n by the o i l of the sea urchins and 'abalones which feed on young kelp,and of 263 the filter-feeding mussels and scallops which feed on the spores. The grazers and their predator, a star fish, gradually repopulated the area, and a balance was once again established after about six years (North et al, 1965). The reduction in species and the proliferation of some resistant types is typical of polluted areas, particularly those suffering from chronic pollution. The pelagic environment is best investigated by the use of captive ecosystems, since in open ocean situations i t is very difficult to follow a specific water mass. The difficulties of maintaining a captive ecosystem are formidable, but the facilities exist as a part of the International Decade of Ocean Exploration project CEPEX (Controlled Ecosystem Pollution Experiment) (Parsons, 1974). Investigations of the effects of hydrocarbons at the parts per billion level have shown stimulation of microflagellates at the expense of diatoms (Parsons et al, 1975). Diatoms are large, and lead to a short, efficient food chain, whereas the smaller microflagellates lead to a long food chain of low efficiency (Ryther, 1969). Broad scale low level pollu-tion by petroleum could result in a shift'towards a microflagellate-based food chain with severe consequences for pelagic fisheries. There are some indications that this process has begun to occur in the North Sea (Fisher, 1976; Reid, 1975). In addition to the disturbance of the balance of species, the dyna-mics of hydrocarbons in the food chain must be considered. It has been demonstrated that chlorinated hydrocarbons (such as DDT), which are widely used as insecticides, are concentrated as they are passed up the food chain (Risebrough et al, 1967). For mineral hydrocarbons i t has been shown that they are sequestered by bacteria (Finnerty et al, 1973), that they can be found in the gut of zooplankton (Conover, 1971), and that they are incorpor-ated into the tissues of f i l t e r feeders (Stainken, 1975; Lee, 1975; Neff and Anderson, 1975). However, passage of hydrocarbons up the food chain is less 264 well-documented. Blumer et al (1970) state that hydrocarbons, once incorpor-ated into a particular marine organism, are stable and may pass through many members of the food chain without alteration. They speculate that poisonous hydrocarbons may be concentrated by the food chain with harmful results for animals at the top (humans). However, no one has been able to document either concentration up the food chain, or resulting harmful effects. For example, Scarrat and Zitko (1972) found evidence of o i l in benthic species after the Arrow s p i l l , but could not detect concentration of the o i l by the food chain. TABLE 32: COMPARISON OF CIRCUMSTANCE AND DOCUMENTED DAMAGE OF OIL SPILLS Spill Locality Date Oil Spilled Detergent Used Damage Tampico Maru (North et al, 1965) Torrey Canyon (Bellamy et al, 1967) (Smith, 1968) Florida (Blumer et a l , 1970) Baja California, Mexico Isles of Scilly off Cornwall, England Falmouth, Mass., USA March 29, 1957 March 18, 1967 September 16, 1969 Diesel, total 9380 m3 (1/3 lost on stranding) 96,000 m3 Kuwait crude None 650-700 mJ No. 2 fuel o i l 2\ million gallons None Very high mortality recorded one month after s p i l l . Six years later recovery almost complete. Rocky cove \ mile 3/4 cove blocked. Damage greatly increased where detergent was used. Subtidal damage blamed on detergent. Detergent on approx. 140 miles English beaches, 75 mi. French. 95-100% mortality in inter-tidal and subtidal areas to 10 meters. June 1970, inter-tidal marsh grass s t i l l dead and no sign of recovery in intertidal areas. Oil Rig (Straughan, 1971) Santa Barbara Channel, USA January 28, 1969 Santa Barbara Crude Oil 43,010 gallons over 13 months at sea Mortality patchy in inter-tidal and confined to areas covered with thick o i l . Recovery of algae and sea-grasses and resettlement of barnacles commenced in 1969. Oil smothering rather than toxic. Con't. Spill Locality Date Oil Spilled Arrow Chedabucto February 10,000 nv (Thomas, 1973) Bay N.S. A, 1970 Bunker C Canada Detergent Used Damage None Fisheries, oyster harvest, algae, eelgrass, a l l apparently unaffected. Clams suffered approx. 20% mortality and beds were closed as a safety measure. Several thousand birds apparently killed. Oil smothering rather than toxic. Much asthetic damage and nuisance - some beaches immobilized for years. TABLE 33: TOXIC CONCENTRATIONS OF CRUDE AND REFINED OILS Definitions M. T. L. (Median tolerance limit): the concentration of toxic material in the r water which is lethal to 50% of its occupants over a specified time (usually 24, 48 or 96 hours). ppm (parts per million): this is an ambiguous measure which indicates different concentrations depending on whether i t refers to parts by weight, parts by volume, or a combination of the two. However, the density of most oils is within about 20% of that of sea water, which is generally less than the experimental error in the measurement of concentrations, so ppm is used throughout to facilitate comparison and may refer to either wt/wt, vol/vol, or mg/1, depending on the original literature source. * indicates the reference is taken from the extensive literature review in Oil Pollution and Marine Ecology by Nelson-Smith, and is not listed separately in this bibliography. Notes 1) Some of the o i l concentration values given in this table have l i t t l e meaning. Crude and residual oils are no more than 100 - 500 ppm soluable in seawater (Anderson et al, 1974), so any concentrations greater than this must refer to emulsions, or to test arrangements in which slicks occur on top of the water phase. 2) When authors present a spectrum of results, the lowest concentration with toxic effects is quoted. 268 CRUDE OIL Concentration (ppm) .01-.03 0.01 0.01 0.05 0.1 0.1-1 0.73 1.6 (Prudhoe) (Middle East) 5 (Venezuelan) 6 Toxic Effect stimulates photosynthesis about 10% Rhombus (fish) eggs survived to hatching, but this was irregular and took longer than usual can impart oily taste to oyster Crassostrea virginica. The taint may persist for six months after heavier doses. water soluable components had no effect on the lobster Homarus  americanus M. T. L. (48 hours) for Rhombus eggs effects on five species of diatoms ranged from stimulation to no effect decreased growth of alevin fry after 10 day exposure causes decrease in net carbon balance of mussels l i t t l e effect on 5 species of zooplankton avoidance threshold (95% con-fidence level) for salmon fry in August herring eggs and fry recorded mortalities of 70% to 100% within the first 3 or 4 days herring larvae normally hatched and transferred to polluted water died within three days thicker Venezuelan crude took 12 days to k i l l herring larvae M. T. L. (96 hours) of pink salmon fry Reference Gordon & Prouse (1973) Mironov (1971) Menzel (1948)* Blumer et al (1973b) Mironov (1971) Prouse et al (1975) 'Rice et al (1975) Gilfillan (1973) Mironov (1971) Rice (1973) Kuhnhold (1971)* Kuhnhold (1971)* Kuhnhold (1971)* Rice et al (1975) 269 CRUDE OIL (Continued) Concentration (ppm) Toxic Effect Reference 8.2 10 (slick) 10 15 10 - 100 16.5 30 - 40 72 100 100 100 100 M. T. L. (24 hours) for the mysid Mysidopsis using water soluable fraction of Kuwait crude effected behaviour and feeding time of the lobster Homarus  americanus reduces feeding of most sensitive form of coral (Madracis asperula) - no recovery M. T. L. (96 hours) for juvenile shiner perch cause larvae of a species of the barnacle Balanus and larvae of crab Pachygrapsus to develop abnormally. M. T. L. (48 hours) for mummichog Fundulus M. T. L. (50 hours) for newly fertilized Black Sea turbot eggs M. T. L. (24 hours) for the mysid Mysidopis using oil-in-water dispersion of Kuwait crude no immediate effect on nauplius larvae of the barnacle Eliminius after several hours exposure 50% k i l l of nauplius larvae of the barnacle Eliminius modestus (contrasts with results of Smith) kill s 5 species of zooplankton within 24 hours 100% mortality to Black Sea turbot eggs within 2 days Anderson et al (1974) Blumer et al (1973b) Lewis (1971) Battelle (1973) Mironov (1971) LaRoche, Eisler & Tarzwell (1970)* Mironov (1967) Anderson et al (1974) Smith (1968)* Spooner (1968)* Mironov (1971) Mironov (1971) 100-500 fresh crude harmed four species of coral Lewis (1971) 270 CRUDE OIL (Continued) Concentration (ppm) Toxic Effect Reference 110 250 400 800-30,000 1,000 (Iranian & Kuwait) 1,000 (Russian) 1,000 (Iranian) 1,000 1,000 7,000 10,000 (Kuwait) >10,000 25,000 extracts from 50,000 M. T. L. (96 hours) for salmon fry at 11.5°C in August (most sensitive time) 3 species of fish - Sargus, wrasse, and mullet remained normally active for several days 'marked toxicity' to small carp M. T. L. (168 hours) for repre-sentative groups of Red Sea macro fauna no effect noticed on guppies within a test period of 15 days causes a 50% mortality to Black Sea topshells within 6-18 days does not k i l l brown shrimp, prawns or brine-shrimp 20% mortality in hydroids (Tubularia) accelerates death of ragworms (Nereis) in sediment M. T. L. (96 hours) Sculpin in sea water causes a depression in the growth rate of the diatom Rhaeodactylum tricornutum M. T. L. (96 hours) Coho fry in fresh water retards multiplication of diatom Nitzschia closterium. Lower levels have a slight stimulatory effect. rapidly toxic to a variety of American fresh water fish Rice (1973) Mironov (1971) Veselov (1948)* Eisler (1975) Capart (1968)* Mironov (1970)* Nelson-Smith (1968) Capart (1968)* Chipman & Galtsoff (1949)* Mironov (1970)* Hebert, Kussat (1972) Lacaze (1967)* Hebert, Kussat (1972) Galtsoff et al (1935)* Wiebe (1935)* CRUDE OIL (Continued) Cone en tra t ion (ppm) Toxic Effect Reference 50,000 complete k i l l of hydroids (Tubularia) within 24 hours Chipman & Galtsoff (1949)' Submergence in 20 different crude oils for one hour duck eggs treated with between 2mg and 36mg of medicinal 'paraffin' o i l showed an aver-age hatch of 20% against 90% in controls underside of ducks smeared with 4-5 ml of o i l before sitting resulted in no eggs hatching mortalities in the snail Littorina littoralis over the 5 days following exposure varied from 1% to 89% at 16°C Hartung (1965)* Hartung (1965)* Ottway (1973)* GASOLINE Concentration (ppm) Toxic Effect Reference 91 60-180 M.T.L. (48 hours) for shad (fish) lethal threshold for trout Tagatz (1961)* Zahner (1962)* KEROSINE 0.1 38 57 100 188 300 10,000 retards the rate of cell divi-sion for the most sensitive species of diatom (Ditylum); other species much more resistant. appreciably depresses growth rate of micro-algae after exposure for several days appreciably decreases growth rate of diatom Asterionella  japonica toxic threshold for diatom (Asterionella japonica) ki l l s diatoms within 24 hours (3 species) toxic threshold to unspecified micro-algae unable to detect toxic effect to goldfish some species of diatoms can tolerate up to this level for 24 hours Mironov (1971) Aubert, Charra, Malara (1969)* Aubert, Charra, Malara (1969)* Aubert, Charra, Malara (1969)* Mironov (1971) Aubert, Charra, Malara (1969)* Aubert, Charra, Malara (1969)* Mironov (1971) 273 DIESEL OIL (No. 2 fuel oil) Concentration (ppm) Toxic Effect Reference 0.04-0.4 .05 .1 - .2 >0.3 1.6 2.6 7.5 100 (emulsion) 100 (emulsion) 167 300-4000 525 (-50°C pour point) stimulates diatom Fragilaria no effect on diatom Durialiella stimulates the growth of the flagellate Chrysochromulina  kappa in a controlled ecosystem enclosure depressed photosynthesis to approximately 60% of controls can significantly inhibit marine bacterial activity, although lower concentrations can enhance i t M.T.L. (24 hours) for the mysid Mysidopsis using water-soluable fraction M.T.L. (24 hours) for Mysidopsis using oil-in-water dispersions M.T.L. (96 hours) for adult shiner perch using dispersed o i l brief exposure irreversibly inhibits photosynthesis in California giant kelp. Effect appears after 7 days. inactivates the tube-feet by which urchins move around. Exposure for more than an hour causes death. M.T.L. (48 hours) for shad (fish) 'lethal threshold' for trout M.T.L. (96 hours) for sculpin in sea water Prouse et al (1975) Parsons et al (1975 Gordon & Prouse (1973) Hodson et al (1975) Anderson et al (1974) Anderson et al (1974) Battelle (1973) North, Neushul, & Clendenning (1964)* North* Tagatz (1961)* Zahner (1962)* Herbert & Kussat (1972) 274 BUNKER C (No . 6 f u e l o i l ) C o n c e n t r a t i o n (ppm) 6.3 780 4 , 8 0 0 2 ,417 1 0 , 0 0 0 1 0 , 0 0 0 1 0 , 0 0 0 1 0 , 0 0 0 T o x i c E f f e c t M . T . L . f o r t he m y s i d M y s i d o p s i s u s i n g o i l - i n - w a t e r d i s p e r s i o n M . T . L . (96 h o u r s ) f o r Coho f r y i n f r e s h w a t e r M . T . L . (96 h o u r s ) f o r s c u l p i n i n s e a w a t e r M . T . L . (48 h o u r s ) f o r shad M . T . L . f o r s a l m o n a t 15°C M . T . L . f o r s a l m o n a t 5°C M . T . L . f o r f l o u n d e r a t 5°C M . T . L . f o r l o b s t e r a t 5°C R e f e r e n c e A n d e r s o n e t a l (1974) H e r b e r t , K u s s a t (1972) H e r b e r t , K u s s a t (1972) T a g a t z ( 1 9 6 1 ) * T a s k F o r c e -O p e r a t i o n O i l (1970) WEATHERED TANK SLUDGE c l o s e p r o x i m i t y t o c o a l t a r d e r i v a t i v e s c u l t u r e s o f m a r i n e p r o t o z o a n s k e p t i n c o n t a c t w i t h w e a t h e r e d s l u d g e showed no i l l e f f e c t s s e a - u r c h i n and s e a s t a r l a r v a e showed a b n o r m a l i t i e s i n d e v e l -opment when k e p t i n s e a w a t e r o v e r w e a t h e r e d s l u d g e h y p e r p l a s m i a i n d u c e d i n t h e e s t u a r i n e h y o z o a n S c h i z o p o r e l l a a t t r i b u t e d t o c a r c i n o g e n s i n t h e p e t r o c h e m i c a l s E l m h i r s t ( 1 9 2 2 ) * E l m h i r s t ( 1 9 2 2 ) * P o w e l l e t a l (1970) 275 AROMATICS Because the aromatic fraction of o i l is generally considered to be the most toxic, the individual aromatic compounds have been studied more closely than other fractions. Concentration (ppm) Benzene 6.6-15.6 10 10 10 20 35-37 100 386-395 1,744 Toxic Effect Reference M.T.L. for pond-snails affects respiratory rate and induces a narcotic effect with prolonged exposure Cairns & Scheier (1962)* Brocksen and Bailey (1973) lethal to roach (fresh water fish) Hubault (1936)* barbel (fish) survive almost indefinitely lethal to sunfish (fresh water) lethal to sunfish (fresh water) barbel (fish) survive for 24 hours lethal to mosquitofish (fresh water) possessed sufficient acute toxicity, despite rapid rates of volatization, to be lethal to Chlorella (algal) cells Toman & Stota (1959)* Turnbull, DeMann & Weston (1954)* Shelford (1917)* Toman & Stota (1959)* from Wallen in McKee (1956)* Kauss et al (1973) Naphthalene .001 30 150-220 threshold of interference with chemoreception in crab Pachygrapsus 2 hours exposure reduces algal cells (Chlamydomonas) ability to photosynthesize to 11% of normal (fresh water) lethal to mosquito fish Kittredge (1973) Kauss et al (1973) from Wallen in McKee (1956)* AROMATICS (Continued) Concentration (ppm) Toxic Effect Reference Toluene 61-65 505 lethal to sunfish sufficient acute toxicity, despite rapid rates of vola-tization, to be lethal to Chlorella (algal) cells Shelford (1917)* Kauss et al (1973) Xylene 47-48 171 lethal to sunfish sufficient acute toxicity, despite rapid rates of vola-tization, to be lethal to Chlorella (algal) cells Shelford (1917)* Kauss et al (1973) Cresols and Phenols 5-10 17 19 72 causes 50% inactivation of kelp photosynthesis in four days toxic to minnows toxic to sunfish toxic to mosquitofish Clendenning and North (1960) Schaut (1939)* Turnbull, DeMann & Weston (1954)* from Wallen in McKee (1956)* 277 APPENDIX C: EXCHANGE RATES OF HYDROCARBONS BETWEEN OCEAN AND ATMOSPHERE (The following discussion i s drawn from the Beaufort Sea Report, 1976, Ocean and Aquatic Sciences, Department of Environment, Canada, by CS. Wong, R.W. MacDonald, W.J. Cretney, and P. Christensen). The best treatment to date of gas exchange between the ocean and atmosphere has been given by L i s s and Slater (1974). Using the i r model, i t i s possible to get an estimate of the residence times of various dissolved hydrocarbons. Consider that the exchange process i s controlled by a two layer interface. The bulk atmosphere and bulk water column are considered to be we l l mixed with a homogeneous concentration of the d i f f u s i n g compound. At steady state F = (C ? - C^ >=k^(Csf - Cp mole/m2hr (1) where F i s f l u x out of the water, k^ and k^  are exchange constants (m/hr). The concentration of hydrocarbon i s expressed as C where C^  refers to the atmosphere, C^  refers to the bulk l i q u i d , and C s and Cs£ refer to the con-centration at the atmosphere and l i q u i d side of the interface respectively. Defining (the o v e r a l l l i q u i d exchange co e f f i c i e n t ) as 1 = 1 + RT where R i s the gas constant, T i s the absolute temperature, and H i s Henry's Law constant, then the f l u x across the atmosphere-ocean boundary can be expressed as 2 F = K ( " — * m o l e ^ m h r where P i s the p a r t i a l (3) ^ pressure of the hydrocarbon i n atm. If i t i s assumed that the atmospheric concentration of the hydrocarbon i s negligible (a v a l i d assumption with the exception of methane), then F - YL.CL mole/m2 hr (4) The f l u x can also be expressed as F = dN = -dC Z mole/m 2 hr (5) dt dt 278 where B i s the depth of the water column considered to be exchanging with the atmosphere. Combining Equation 4 and 5 and integrating gives C - C exp -K. Q t ( 6 ) ° 'g * so the half l i f e of a spike of a hydrocarbon i n the water column i s given by t, = Z In 2 (7) Li s s and Slater have given t y p i c a l oceanic values of the exchange constants as .02 m/hr for k„ and 3.0 m/hr for k at 25°C. Using these values corrected I g for molecular weight and setting the depth to 1 m, the and t ^ values can be calculated. These are presented i n Table 34 along with the values at 0°C. The lower temperature constants were calculated by assuming k^  and k^  were assoc-iated with activation energies of about 5 kcal/mole. The data of Schooley (1969) shows that t h i s i s a f a i r approximation. From Table 34 i t i s apparent that the half l i v e s of hydrocarbons i n the water increase by a factor of about 2 for most hydrocarbons on going from 25°C to 0°C. The polynuclear aromatics are extremely slow i n being removed, for phenanthrene being 248 hours. I t has been shown that the exchange constants k. and k are influenced by wind v e l o c i t y . There i s a l i n e a r increase i n k with wind v e l o c i t y , while .9 k^ increases as the square of wind v e l o c i t y (Liss and Sla t e r , 1974). As a r e s u l t , hydrocarbons w i l l be removed by exchange faster at a high wind v e l o c i t y . I f bubbles are injected by turbulence down into the water column, they can e f f e c t i v e l y s t r i p some dissolved hydrocarbons from the water. Perhaps the easiest way to v i s u a l i z e t h i s process i s to examine the p a r t i t i o n i n g of various hydrocarbons between the gas and l i q u i d phase when equal volumes of both phases are equilibrated. Table 35 presents this information f o r selected hydrocarbons at 0°C and 25°C. The v o l a t i l e alkanes can be e f f i c i e n t l y removed 279 from the water by bubbles, but the aromatics do not s t r i p out very w e l l and the higher molecular weight hydrocarbons cannot be removed at a l l well by this mechanism. 280 TABLE 34: Theoretical Half Lives of Dissolved Hydrocarbons Exchanging with the Atmosphere , Hydrocarbon 0°C i t, (hours) 25°C h t, (hours) "2 Hexane .066 10.5 .143 4.82 Octane .057 12.0 .124 5.56 Decane .051 13.5 .111 6.22 Dodecane .047 14.7 .102 6.76 Tetradecane .044 15.9 .094 7.34 Hexadecane .041 17.0 .0088 7.80 Cyclohexane .067 10.3 .145 4.75 Benzene .064 10.8 .143 4.82 Toluene .061 11.3 .133 5.18 Ethyl Benzene .068 12.0 .126 5.48 Cumene .055 12.6 .119 5.80 Naphthalene .0046 151. .069 9.98 Biphenyl .015 46.6 .077 9.01 Fluorene .0049 137 .049 14.0 Anthracene .0036 194 .086 8.1 Phenanthrene .0028 248 .037 18.9 TABLE 35: Partitioning of Hydrocarbons Between Equal Volumes of Gas and Liquid Phases  % in gas % in gas Hydrocarbon phase 0°C phase 25°C n-hexane 97.7 98.7 m-octane 98.3 99.5 n-decane 99.4 99.5 n-dbdecane 99.4 99.7 n-hexadecane 99.3 90.1 Cyclohexane 67.2 86.9 Benzene 11.2 8.6 Toluene 17.8 20.3 Ethyl Benzene 24.5 29.2 o-xylene. 15.1 18.5 Durene 33.5 50.6 Naphthalene 0.10 1.71 Biphenzyl 0.44 ^ 2.54 Fluorene 0.12 0.95 Anthracene 0.08 6.32 Phenanthrene 0.07 0.60 APPENDIX D: A Personal Perspective on the O i l P o l l u t i o n Problem 282 Petroleum i s a natural product which has undergone chemical r e s t r u c -turing due to g e o l o g i c a l pressures, temperatures, and time sc a l e s . Many of the components of o i l are analogs of present-day n a t u r a l products, and are e a s i l y assimilated by the b i o l o g i c a l system, providing both an energy and a carbon source. Other components of o i l are les s f a m i l i a r and more r e f r a c t o r y . However, no'component of o i l has yet been i s o l a t e d which cannot be degraded by some form of microorganism. Degradation of petroleum has been demonstrated to occur i n a v a r i e t y of marine environments i n t h i s t h e s i s , a l b i e t sometimes at slow rates. My personal synthesis of a l l the masses of published work on the b i o l o g i c a l e f f e c t s of o i l p o l l u t i o n suggests to me the following: v i o l e n t d i s r u p t i o n of the environment by large o i l s p i l l s from supertankers w i l l con-tinue to occur from time to time. The l o c a l f l o r a and fauna (including humans) w i l l be d r a s t i c a l l y e f f e c t e d , but the e f f e c t s w i l l be l i m i t e d to the area re c e i v i n g the s p i l l , and recovery w i l l occur over a period of years. Chronic p o l l u t i o n of near-shore waters w i l l r e s u l t i n decreased d i v e r s i t y and product-i v i t y there. Unusually s e n s i t i v e species may be severely a f f e c t e d by low l e v e l s of petroleum hydrocarbons, and be eliminated from areas of t h e i r range. However, the g l o b a l marine ecosystem, which i s a vast and stable s t r u c t u r e , w i l l probably not be noticeably perturbed by petroleum p o l l u t i o n . The main impact of petroleum on the environment w i l l , I think, come i n quite another d i r e c t i o n . The increasing use of petroleum over the l a s t century has seen i t become an i n t e g r a l part of our d a i l y l i v e s as a f u e l , as chemicals, pharmaceuticals, p l a s t i c s , synthetics of a l l d e s c r i p t i o n s . Our population and our expectations have r i s e n exponentially with the exponential r i s e i n the e x p l o i t a t i o n of o i l . We have committed ourselves i r r e v o c a b l y to a dependence on a continued supply. The r a m i f i c a t i o n s of our dependence have 283 been c l e a r l y f e l t over the l a s t few years, r e q u i r i n g i n t e r n a t i o n a l co-operation on a scale never before seen. The network of petroleum production and u t i l i z a -t i o n i s so vast, i n t e g r a t i n g such a myriad of governments, i n t e r n a t i o n a l cor-porations, and s o c i a l systems that the complexities have become well-nigh unmanageable. This complex balance of power w i l l be s e r i o u s l y s t r a i n e d as supplies become harder and harder to obtain. Governments, caught between a populace angry at t h e i r f a l l i n g standard of l i v i n g , and an i n t e r n a t i o n a l s i t u a t i o n i n which they are powerless to act except by force, w i l l have l i t t l e option except to protect t h e i r own i n t e r e s t s . The importance of petroleum as a source of i n t e r n a t i o n a l tension and c o n f l i c t cannot be underestimated, and the spectre of war over petroleum supplies i s very r e a l . Modern warfare with the use of nuclear, chemical, b i o l o g i c a l and powerful conventional weapons i s the ultimate environmental hazard on a scale orders of magnitude above the prosaic problems of hydro-carbon p o l l u t i o n . I argue that petroleum p o l l u t i o n i s not and w i l l not be, one of man's c r u c i a l problems. Instead, i t i s the e f f e c t on our s o c i a l ecosystem, and the r e s u l t i n g p o t e n t i a l f o r warfare, that i s the c r u c i a l environmental problem posed by petroleum. APPENDIX E : S y m p o s i a and Books D e a l i n g w i t h O i l P o l l u t i o n 2 8 4 A h e a r n , D . G . ; and S . P . M e y e r s ( e d s . ) . 1 9 7 3 . The M i c r o b i a l D e g r a d a t i o n o f O i l  P o l l u t a n t s . Workshop h e l d a t G e o r g i a S t a t e U n i v e r s i t y , A t l a n t a , i n December 1 9 7 2 . L o u s i a n a S t a t e U n i v e r s i t y p u b l i c a t i o n n o . L S U - S G - 7 3 - 0 1 . C a r t h y , J . D . and D . R . A r t h u r ( e d s . ) , 1 9 6 8 . The B i o l o g i c a l E f f e c t s o f O i l  P o l l u t i o n on L i t t o r a l C o m m u n i t i e s . P r o c e e d i n g s o f a sympos ium h e l d a t O r i e l t o n F i e l d C e n t r e , P e n b r o k e W a t e r s , 1 7 - 1 9 F e b r u a r y , 1 9 6 8 . F i e l d S t u d i e s _2 ( s u p p l e m e n t ) . A l c a n S h i p p i n g S e r v i c e s L t d . , 1 9 7 1 . P o l l u t i o n and t he M a r i t i m e I n d u s t r y . 3 v o l u m e s . P r e p a r e d unde r c o n t r a c t t o U . S . D e p t . o f T r a n s p o r t . C o w e l l , E . B . ( e d . ) . 1 9 7 1 . The E c o l o g i c a l E f f e c t s o f O i l P o l l u t i o n on  L i t t o r a l C o m m u n i t i e s . P r o c e e d i n g s o f a sympos ium h e l d 30 November t o 1 December , 1 9 7 0 . I n s t i t u t e o f P e t r o l e u m , L o n d o n . H e p p l e , P . ( e d . ) . 1 9 6 8 . S c i e n t i f i c A s p e c t s o f P o l l u t i o n o f t h e Sea by O i l . P r o c e e d i n g s o f a sympos ium h e l d 2 O c t o b e r , 1 9 6 8 . I n s t i t u t e o f P e t r o l e u m , L o n d o n . H e p p l e , P . ( e d . ) . 1 9 7 1 . Wa te r P o l l u t i o n by O i l . P r o c e e d i n g s o f a s e m i n a r h e l d a t A v i e m o r e , S c o t l a n d , 4 -8 May , 1 9 7 0 . A p p l i e d S c i e n c e , E s s e x , E n g l a n d . H o u l t , D . P . ( e d . ) . 1 9 6 9 . O i l on t h e S e a . P r o c e e d i n g s o f a sympos ium h e l d a t C a m b r i d g e , M a s s a c h u s e t t s , 16 M a y , 1 9 6 9 . P l enum P r e s s , New Y o r k . IMCO, 1 9 7 3 . The E n v i r o n m e n t a l and F i n a n c i a l C o n s e q u e n c e s o f O i l P o l l u t i o n  f r o m S h i p s . R e p o r t o f s t u d y n o . V I , s u b m i t t e d by t h e U . K . t o t h e 1973 I n t e r g o v e r n m e n t a l M a r i n e P o l l u t i o n C o n f e r e n c e . M a r i n e P o l l u t i o n M o n i t o r i n g ( P e t r o l e u m ) . 1 9 7 4 . P r o c e e d i n g s o f a sympos ium and workshop h e l d a t t h e N a t i o n a l B u r e a u o f S t a n d a r d s , G a i t h e r s b u r g , M d . , 13 -17 M a y , 1 9 7 4 . N a t i o n a l B u r e a u o f S t a n d a r d s S p e c i a l P u b l i c a t i o n 4 0 9 , W a s h i n g t o n , B . C . N e l s o n - S m i t h , A . 1 9 7 2 . O i l P o l l u t i o n and M a r i n e E c o l o g y . E l e k S c i e n c e , L o n d o n . O i l P o l l u t i o n of the S e a . 1 9 6 8 . R e p o r t o f p r o c e e d i n g s o f an i n t e r n a t i o n a l c o n f e r e n c e h e l d i n Rome, 7 -9 O c t o b e r , 1 9 6 8 . Wykeham P r e s s , E n g l a n d . 285 P r e v e n t i o n and C o n t r o l of O i l S p i l l s . 1969. Proceedings of a j o i n t conference on 15-17 December, 1969, i n New York. American Petroleum I n s t i t u t e , New York. Pre v e n t i o n and C o n t r o l of O i l S p i l l s . 1971. Proceedings of a j o i n t conference on 15-17 June, 1971, i n Washington, D.C. American Petroleum I n s t i t u t e , Washington. Prevention and C o n t r o l of O i l S p i l l s . 1973. Proceedings of a j o i n t conference on 13-15 March, 1973, i n Washington, D.C. American Petroleum I n s t i t u t e , Washington. Prevention and C o n t r o l of O i l P o l l u t i o n . 1975 Proceedings of a conference on 25-27 March, 1975, i n San F r a n s i s c o , C a l i f o r n i a . American Petroleum I n s t i t u t e , Washington. Ruivo, M. (ed.). 1972. Marine P o l l u t i o n and Sea L i f e . Proceedings of the Food and A g r i c u l t u r e O r g a n i z a t i o n of the United Nations t e c h n i c a l conference on marine p o l l u t i o n and i t s e f f e c t s on l i v i n g resources and f i s h i n g , h e l d 9-18 December, 1970, at FAO Headquarters, Rome. F i s h i n g News (Books) l t d . London. Smith, J.E. (ed.). 1968. 'Torrey Canyon' P o l l u t i o n and Marine L i f e . A r e p o r t by the Plymouth Laboratory of the Marine B i o l o g i c a l A s s o c i a t i o n of the United Kingdom. U n i v e r s i t y P r e s s , Cambridge. Study of C r i t i c a l Environmental P r o p e r t i e s (SCEP). 1970. Man's impact on the g l o b a l environment. Assessment and recommendations f o r a c t i o n . MIT P r e s s , Cambridge, Mass. Symposium on Marine P o l l u t i o n . 1973. Proceedings of a symposium h e l d at the at the N a t i o n a l P h y s i c a l Laboratory, Teddington, 27-28 February, 1973. Royal I n s t i t u t i o n of Naval A r c h i t e c t s , London. Task Force - Operation O i l . 1970. Report of the clean-up of the Arrow o i l s p i l l i n Chedabucto Bay, Nova S c o t i a , Canada. 3 volumes. Information Canada, Ottawa. 

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