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The geochemistry and diatom assemblages of varved sediments from Saanich Inlet, B.C. Powys, Richard I. L. 1987

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THE GEOCHEMISTRY AND DIATOM ASSEMBLAGES OF VARVED SEDIMENTS FROM SAANICH INLET, B.C. by RICHARD I.L POWYS B . S c , Un ivers i ty of Wales, Swansea. 1984. A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES (OCEANOGRAPHY) We accept t h i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA August 1987 ©Richard I .L Powys, 1987 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of The University of British Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date ( A t ^ S r U ^ I ABSTRACT Varved, anoxic sediments in Saanich In le t , B r i t i s h Columbia, are formed by the annual cyc le of summer deposi t ion of diatom f rustu les and winter inputs of terr igenous material derived from land runoff . The object ive of th is study was to sample the varve record in order to develop a palaeoceanographic h is tory of the In le t . Box-cores of varved sediments were c o l l e c t e d from Fin layson Arm, Saanich In le t . The cores were quick, frozen upon recovery, to preserve the laminae, were subsequently sect ioned and X-radiographs of the sect ions prepared. The varves were i n d i v i d u a l l y sampled and analysed for the i r diatom assemblages together with carbon, carbonate, major and minor element concentrat ions and 2 1 ° P b a c t i v i t y . The chronology of a representat ive core determined by 2 l o P b was inconsis tent with that determined by varve count ing. The geochemical data indicated that the upper 15cm of the core had a d i s t i n c t elemental composition and a lower poros i ty that indicated a changed sedimentation ra te . It a lso appeared that around 20 years of sediment had been l o s t from the core - top . The upper sediment contains a carbonate increase l inked to a dust dump from a l o c a l cement plant which occurred between 1960-1963. In the lower sec t ion of the core , both the diatom and the geochemical data indicate seasonal v a r i a t i o n expected from the formation of annual i i i varves. However, a well constrained chronology cannot be obtained for th is core because of the non-steady state sedimentation. This makes the in te rpre ta t ion of in ter -varve var ia t ions in the l i g h t of regional c l i m a t i c records impossible . Nevertheless, a change in production on a cycle of approximately 10-15 years i s evident and th is study provides conclusions that w i l l be useful to future palaeoceanographic invest iga t ions on longer cores from a part of the In let where sedimentation is more constant. iv TABLE OF CONTENTS. PAGE CHAPTER 1; INTRODUCTION. 1 1.1 The study of varved sediments 1 1.2 Object ives of the study. 5 1.3 A review of the oceanography of Saanich In le t . 6 1.4 Geological summary of the Saanich In let area. 12 CHAPTER 2; METHODS 15 2.1 Core c o l l e c t i o n and sample preparat ion. 15 2.2 Geochronology using 210Pb. 21 2.3 Determination of bulk, mineralogy and the major and minor element concentrat ions by X-ray a n a l y s i s . 22 2.4 Determination of carbon, ni t rogen and carbonate. 23 2.5 Sample preparat ion and counting of diatoms. 24 CHAPTER 3; RESULTS 26 3.1 Chronology of the core by 210Pb. 26 3.1.1 C a l c u l a t i o n of sediment accumulation ra te . 32 3.1.2 Determination of the sedimentation rate using poros i ty data from Matsu-moto and Wong (1977). 35 3.1.3 C a l c u l a t i o n of porosi ty from the measured ch lor ine concentrat ions. 37 3.2 Organic carbon and the carbon:ni trogen r a t i o . 45 3.3 Carbonate. 56 3.4 Bulk mineralogy and the major elements. 63 3.4.1 Mineralogy. 63 3.4.2 Major elements. 68 3.5 The geochemistry of minor elements. 89 3.5.1 Absolute abundances of minor elements. 92 3.5.2 Ratios of minor elements to aluminium. I l l 3.6 The diatom record . 117 3.6.1 Preparat ion of a peel s l i d e of the varves. 117 3.6.2 Diatom count ing. 125 CHAPTER 4: DISCUSSION. 136 CHAPTER 5; SUMMARY AND CONCLUSIONS. 148 5.1 Summary. 148 5.2 Conclusions. 152 V PAGE BIBLIOGRAPHY. 155 APPENDIX A. Determination of 210Pb. 165 APPENDIX B. X-ray f luorescence methods. 170 APPENDIX C. Chlor ine a n a l y s i s . 185 APPENDIX D. Carbon, ni t rogen and carbonate determination. 189 APPENDIX E. Preparat ion and counting of diatoms. 195 v i LIST OF FIGURES. PAGE CHAPTER ONE. F i g . 1.2.1 Locat ion of Saanich In let showing bathymetry and ind ica t ing cor ing l o c a t i o n s . 7 F i g . 1.2.2 Saanich In let showing the main r i v e r s in f luenc ing sedimentation. 10 F i g . 1.3.1 Geological sketch map of the Saanich In let area. 13 CHAPTER THREE.  SECTION 3.1. F i g . 3.1.1 P r o f i l e of the 210Pb a c t i v i t y i n core CPIV. 29 F i g . 3.1.2 P r o f i l e of ch lor ide concentrat ions. 33 F i g . 3.1.3 Corrected depth p lot ted against excess 210Pb. 36 F i g . 3.1.4 Corrected depth (based on ch lor ide poro-s i t y ) against 210Pb. 41 SECTION 3.2. F i g . 3.2.1 P r o f i l e of organic carbon. 48 F i g . 3.2.2 P r o f i l e of the C:N r a t i o . 48 F i g . 3.2.3 P r o f i l e of the S i : A l r a t i o . 51 F i g . 3.2.4 P r o f i l e of % Opal. 51 F i g . 3.2.5 P r o f i l e of opa l - f ree organic carbon. 53 F i g . 3.2.6 D i s t r i b u t i o n of diatom counts. SECTION 3.3. F i g . 3.3.1 P r o f i l e of carbonate. 57 F i g . 3.3.2 Carbonate d i s t r i b u t i o n in the surface sediments of Saanich In le t . 58 SECTION 3.4. F i g . 3.4.1 Examples of XRD spectra . 64 F i g . 3.4.2 The q u a r t z : c h l o r i t e r a t i o . 66 F i g . 3.4.3 The quar tz : fe ldspar r a t i o . 66 F i g . 3.4.4 P r o f i l e of S i l i c o n . 70 F i g . 3.4.5 The s i l icon:a lumin ium r a t i o . <• 70 F i g . 3.4.6 P r o f i l e of Aluminium. 72 F i g . 3.4.7 P r o f i l e of Iron. 73 F i g . 3.4.8 The iron:aluminium r a t i o . 74 F i g . 3.4.9 The potassium:aluminium r a t i o . 74 F i g . 3.4.10 P r o f i l e of Potassium. 76 F i g . 3.4.11 P r o f i l e of Titanium. 77 F i g . 3.4.12 The titanium:aluminium r a t i o . 79 F i g . 3.4.13 The magnesium:aluminium r a t i o . 79 F i g . 3.4.14 P r o f i l e of Calcium. 81 F i g . 3.4.15 P r o f i l e of Magnesium. 82 F i g . 3.4.16 P r o f i l e of Phosphorus. 84 F i g . 3.4.17 The carbon:phosphorus r a t i o . 85 v i i PAGE SECTION [ 3 .5 . F i g . 3. 5. 1 P r o f i l e of Barium. 91 F i g . 3. 5. 2 The barium:potassium r a t i o . 91 F i g . 3. 5. 3 P r o f i l e of Chromium. 93 F i g . 3. 5. 4 The chromium:iron r a t i o . 93 F i g . 3. 5. 5 P r o f i l e of Copper. 96 F i g . 3. 5. 6 P r o f i l e of Manganese. 96 F i g . 3. 5. 7 P r o f i l e of Molybdenum. 97 F i g . 3. 5. 8 P r o f i l e of N i c k e l . 97 F i g . 3. 5. 9 P r o f i l e of Rubidium. 100 F i g . 3. 5. 10 P r o f i l e of Strontium. 100 F i g . 3. 5. 11 P r o f i l e of Vanadium. 103 F i g . 3. 5. 12 The vanadium:iron r a t i o . 103 F i g . 3. 5. 13 P r o f i l e of Yttr ium. 105 F i g . 3. 5. 14 P r o f i l e of Z inc . 105 F i g . 3. 5. 15 The z i n c : i r o n r a t i o . 106 F i g . 3. 5. 16 P r o f i l e of Lead. 106 F i g . 3. 5. 17 P r o f i l e of Zirconium. 108 F i g . 3. 5. 18 The barium:aluminium r a t i o . 110 F i g . 3. 5. 19 The chromium:aluminium r a t i o . 110 F i g . 3. 5. 20 The copper:aluminium r a t i o . 112 F i g . 3. 5. 21 The nickel:aluminium r a t i o . 112 F i g . 3. 5. 22 The rubidium:aluminium r a t i o . 113 F i g . 3. 5. 23 The strontium:aluminium r a t i o . 113 F i g . 3. 5. 24 The vanadium:aluminium r a t i o . 114 F i g . 3. 5. 25 The yttrium:aluminium r a t i o . 114 F i g . 3. 5. 26 The zinc:aluminium r a t i o . 116 F i g . 3. 5. 27 The lead:aluminium r a t i o . 116 SECTION f 3 .6 . F i g . 3. 6. 1 D i s t r i b u t i o n of diatom counts ( c e l l s / g ) . 126 F i g . 3. 6. 2 Relat ive abundances of diatom groups. 128 F i g . 3. 6. 3 Counts of benthic spec ies . 130 F i g . 3. 6. 4 Counts of planktonic spec ies . 130 F i g . 3. 6. 5 Counts of the Chaetoceros group. 132 F i g . 3. 6. 6 Counts of Skeletonema costatum. 132 F i g . 3. 6. 7 Counts of the T h a l a s s i o s i r a group. 134 v i i i LIST OF TABLES. PAGE TABLE I Deta i ls of recovered cores . 16 TABLE II Results of 210Pb a n a l y s i s . 27 TABLE III Comparison between 210Pb chronology and 137Cs a c t i v i t y . 31 TABLE IV Comparison between varve counts and 137Cs a c t i v i t y . 31 TABLE V Sediment accumulation rates in Saanich In le t . 37 TABLE VI C a l c u l a t i o n of porosi ty based on ch lor ide data. 38 TABLE VII Carbon, carbonate, n i t rogen , carbon: ni trogen r a t i o and %opal r e s u l t s . 47 TABLE VIII Summary of major element concentrat ions. 69 TABLE IX Summary of minor element concentrat ions. 87 TABLE X Summary of diatom counts. 124 ix APPENDIX TABLES. APPENDIX A. TABLE Al APPENDIX B. TABLE BI TABLE BII TABLE B i l l TABLE BIV TABLE BV TABLE BVI TABLE BVII TABLE BVIII TABLE BIX TABLE BX TABLE BXI TABLE BXII APPENDIX C. TABLE CI APPENDIX D. TABLE DI TABLE DII TABLE D i l i APPENDIX E. TABLE EI PAGE Estimate of Ortec instrument p r e c i s i o n . 169 XRF instrument cond i t ions . 176 Standards used in c a l i b r a t i o n of major elements. 177 Standards run as unknowns during major element a n a l y s i s . 178 Estimate of instrument p r e c i s i o n for the major elements. 179 Between sample p r e c i s i o n estimate for the major elements. 179 Comparison between minor element contents of 0.5 and l .Og p e l l e t s and estimate of instrument p r e c i s i o n . 180 Standards used in the c a l i b r a t i o n of the minor elements. 181 Standards run as unknowns during minor element a n a l y s i s . 182 C a l i b r a t i o n standards for sulphur. 183 Standards run as unknowns for sulphur. 183 C a l i b r a t i o n standards for molybdenum. 184 Standards run as nuknowns for molybdenum. 184 Chlor ide c a l c u l a t i o n s . 188 Estimate of p r e c i s i o n for the ana lys is of carbon and n i t rogen. 192 Results of ni t rogen a n a l y s i s . 193 Results of carbon and carbonate a n a l y s i s . 194 Species l i s t of observed diatoms 198 X LIST OF PLATES. PAGE PLATE I X-radiographs of the sampled cores . 18 PLATE II An example of a dark lamina. 118 PLATE III An example of a dark lamina containing some c e n t r i c diatoms. 118 PLATE IV . The junct ion between a dark and a l i g h t lamina. 120 PLATE V An example of a d i s t i n c t bloom of S.costatum. 120 PLATE VI An example of a poorly defined bloom of S.costatum. 121 PLATE VII The c h a r a c t e r i s t i c assemblage of a l i g h t lamina. 121 PLATE VIII Junct ion between a l i g h t and a dark lamina showing Chaetoceros spores. 123 PLATE IX Showing a bloom of the s i l i c o f l a g e l l a t e Distephanus speculum. 123 1 CHAPTER 1: INTRODUCTION. 1.1 The study o f varved sediments. During the past 20 yea r s , there have been a number of s t u d i e s o f diatomaceous sediments which accumulate i n anoxi c bottom waters along the west c o a s t o f North America (Gross and Gucluer, 1963; Calvert, 1964,1966a,1966b; Gucluer and Gross, 1964; Soutar, 1966; Soutar and Isaacs, 1974; Soutar and Crill, 1977; Donegan and Schrader, 1982; Schrader and Baumgartner, 1983; Heusser, 1983 and Baumgartner et al. 1985). Since anoxic bottom waters, d e f i n e d here as waters c o n t a i n i n g l e s s than O.lml./L. oxygen, r e q u i r e s p e c i a l oceanographic and/or g e o l o g i c a l c o n d i t i o n s , t h e i r occurrence i s l i m i t e d to a small number o f l o c a l i t i e s . The s t u d i e s r e -f e r r e d to c o n c e n t r a t e on three such environments: 1: The G u l f o f C a l i f o r n i a ; p a r t i c u l a r l y the Guay-mas b a s i n (Calvert, 1964,1966a,1966b; Donegan and Schrader,1982; Schrader and Baumgartner, 1983; Baumgartner et al. 1985.) 2: B l o c k - f a u l t e d b a s i n s on the c o n t i n e n t a l margin o f southern C a l i f o r n i a (Bruland et al., 1974), p a r t i c u l a r l y the Santa Barbara b a s i n (Soutar, 1966; Soutar and Isaacs, 1974; Soutar and Crill, 1977). 2 3: Saanich I n l e t , B r i t i s h Columbia (Gross and Gu-cluer, 1963; Gucluer and Gross, 1964; Gross, 1967; Heusser, 1983). A l l these s t u d i e s have r e c o g n i s e d t h a t where ben-t h i c macrofauna are excluded by the anox i c nature o f the bottom waters and, hence, b i o t u r b a t i o n i s absent, the sediments c o n t a i n a r e c o r d o f d e p o s i t i o n i n l a y e r s t h a t conform to the d e f i n i t i o n o f varves f i r s t proposed by De Geer (1912), namely d i s t i n c t l y marked annual d e p o s i t s . Furthermore, these s t u d i e s showed t h a t the varves c o n s i s t e d of a l t e r n a t i n g l i g h t and dark l a m i n a t i o n s and t h a t the l i g h t l a y e r s c o n s i s t e d mainly o f biogenous s i l i c a , and thus r e p r e s e n t e d a r e c o r d o f seasonal p r o d u c t i o n by phytoplankton i n the s u r f a c e waters, while the dark l a y e r s c o n t a i n e d more li t h o g e n o u s m a t e r i a l d e r i v e d from t e r r e s t r i a l r u n o f f d u r i n g the season o f high r a i n f a l l . In the c e n t r a l G u l f o f C a l i f o r n i a , p r o d u c t i o n ap-pears to be almost continuous throughout the year, although l o c a l p a t t e r n s are com p l i c a t e d by wind-driven u p w e l l i n g . The season o f h i g h r a i n f a l l o ccurs d u r i n g the summer. V a r i a t i o n s i n the r a i n f a l l , and hence t e r r e s t r i a l r u n o f f , were o r i g i -n a l l y thought to produce the varves (Calvert, 1966b); how-ever, Donegan and Schrader (1982) have s i n c e shown t h a t the diatom f r u s t u l e s which they c o n t a i n r e f l e c t seasonal v a r i a -t i o n i n primary p r o d u c t i o n i n a d d i t i o n to the t e r r e s t r i a l i n p u t . 3 I n the C a l i f o r n i a b a s i n s and Saanich I n l e t , on the other hand, b i o l o g i c a l p r o d u c t i o n and p e r i o d s o f hig h r a i n -f a l l are c l e a r l y s e a s o n a l l y d e f i n e d . Here the peak i n phyto-p l a n k t o n p r o d u c t i o n occurs i n the spring/summer, while the h i g h e s t r a i n f a l l o ccurs i n the winter. I n Saanich I n l e t , there i s an a d d i t i o n a l i n p u t o f t e r r e s t r i a l m a t e r i a l d u r i n g the e a r l y summer which i s d e r i v e d from the F r a s e r R i v e r f r e s h e t , a t i t s maximum i n June. In these two l o c a t i o n s the l i g h t and dark l a y e r s i n the varves have been a s s o c i a t e d with summer and winter d e p o s i t i o n , r e s p e c t i v e l y (Gross and Gucluer, 1963; Soutar and Crill, 1977). A review o f the d e p o s i t i o n a l s e t t i n g s and the oceanography o f these areas i s pro v i d e d by Soutar et al. (1981). S c i e n t i f i c i n t e r e s t i n these sediments has been s t i m u l a t e d by two o b s e r v a t i o n s . F i r s t l y , the sediments r e p -r e s e n t modern analogues o f the diatomaceous Honterey Forma-t i o n o f C a l i f o r n i a and thereby p r o v i d e modern e q u i v a l e n t s o f the source r o c k s f o r the e x t e n s i v e o i l r e s e r v e s o f C a l i f o r -n i a (Donegan and Schrader,1981; Ingle, 1981). Secondly, and of f a r g r e a t e r i n t e r e s t to the new d i s c i p l i n e o f p a l a e o -ceanography, the seasonal and annual r e c o r d r e p r e s e n t e d by the varves p r o v i d e s both a convenient sediment chronology and a r e c o r d o f c l i m a t i c and oceanographic changes t h a t have o c c u r r e d i n the pas t . Lamina t h i c k n e s s has been c o r r e l a t e d with v a r i a t i o n s i n r a i n f a l l (Soutar and Crill, 1977) making them analogous to t r e e - r i n g s , as p r e d i c t e d by Calvert (1966b). In a d d i t i o n , i n t e r - l a y e r d i f f e r e n c e s i n the diatom 4 assemblages preserved i n such sediments have been c o r r e l a t e d with oceanographic changes, e s p e c i a l l y the E l Nino/Southern O s c i l l a t i o n (ENSO) by Baumgartner et al (1985), while i n the G u l f o f C a l i f o r n i a Murray and Schrader (1982/83) have c o r r e -l a t e d the s i l i c o f l a g e l l a t e r e c o r d with changes i n the oceanographic regime o f t h a t area. The r e c o r d o b t a i n a b l e from such sediments, e p i t o m i z e d by the 152m. h y d r a u l i c p i s -ton core c o l l e c t e d by the Deep Sea D r i l l i n g P r o j e c t a t S i t e 480 i n the G u l f o f C a l i f o r n i a (Curray and Moore, 1982), has been regarded as a s i g n i f i c a n t t o o l f o r the study o f p a l a e o -ceanography. In a d d i t i o n to work on the diatom assemblages o f these sediments, Soutar (1966) and Sootar and Isaacs (1974) have s t u d i e d the occurrence o f f i s h s c a l e s i n the Santa Bar-bara b a s i n varves and have r e l a t e d t h e i r v a r i a t i o n s to changes i n the flow o f the C a l i f o r n i a C u r r ent system and to annual f l u c t u a t i o n s i n commercial f i s h s t o c k s , e s p e c i a l l y the P a c i f i c hake M e r l u c c i u s productus and the P a c i f i c s a r -dine Sardlnops c a e r u l e a . P a l y n o l o g i c a l s t u d i e s o f the s e d i -ments o f Saanich I n l e t have focused on v e g e t a t i o n and c l i -matic changes s i n c e the r e t r e a t o f g l a c i a l i c e some 12,000 years ago and on r e c e n t changes i n l a n d use (Heusser, 1983). L i m i t e d s t u d i e s o f the geochemistry o f the lamina-t i o n s w i t h i n such sediments have been r e p o r t e d by Cucluer and Gross (1964) and Gross (1967) i n Saanich I n l e t , and by Calvert (1966a) and Donegan and Schrader (1982) i n the G u l f o f C a l i f o r n i a . However, these geochemical s t u d i e s o f t e n 5 looked o n l y a t s h o r t s e c t i o n s o f the laminated sediment r e c o r d s . No study has r e p o r t e d r e s u l t s from a complete core analysed varve by varve s t a r t i n g a t the sediment/water i n -t e r f a c e , and o n l y Donegan and Schrader (1982), r e p o r t i n g work i n the G u l f o f C a l i f o r n i a , have attempted to l i n k geo-chemical v a r i a t i o n s from a d e t a i l e d study o f s h o r t varved s e c t i o n s to s i g n a l s o f c l i m a t i c or oceanographic change. 1.2 O b j e c t i v e s o f the study. The o r i g i n a l aim o f t h i s study was to c o n s t r u c t a palaeoceanographic and p a l a e o c l i m a t i c r e c o r d f o r the area by sampling a varved box core from Saanich I n l e t . The i n t e n t i o n was to sample each varve lamina by lamina and perform a f u l l geochemical and diatom a n a l y s i s on the samples c o l l e c t e d and to compare these data with a v a i l a b l e c l i m a t i c and oceano-g r a p h i c r e c o r d s . Such a study would: 1: I d e n t i f y an e a s i l y measured geochemical v a r i -a ble which might be l i n k e d to c l i m a t i c or oceanographic v a r i a t i o n s i n the r e g i o n . 2: Provide a r e c o r d o f the e f f e c t s o f ENSO events on the S t r a i t o f Georgia system by determining the o c c u r -rence o f warm water diatoms (eg: P l a n k t o n i e l l a s o l and Pseu-doeunotia d o l l o l u s ) c a r r i e d n o r t h along the west c o a s t o f North America and i n t o Saanich I n l e t . 3: Provide an i n d i c a t i o n o f past changes i n the primary p r o d u c t i o n o f Saanich I n l e t . 6 4: Corroborate the assumption t h a t the laminae and varves found i n the I n l e t do indeed r e p r e s e n t annual d e p o s i -t i o n . These o b j e c t i v e s depended on the es t a b l i s h m e n t o f a sound chronology f o r the co r e . I t was e s s e n t i a l t h a t any trends observed c o u l d be dated and thus r e l a t e d to c l i m a t i c i n f o r m a t i o n a v a i l a b l e f o r the area. I t was hoped t h a t the varves, i n c o n j u n c t i o n with the measurement o f * 1 0Pb, would p r o v i d e such a chronology. However, a comparison o f varve counts i n the top o f the core s t u d i e d and a*°Pb data r e -ve a l e d a major d i s c r e p a n c y i n ages a s s i g n e d to the c o l l e c t e d samples. Because o f the observed d i s c r e p a n c y i n the i n i t i a l chronology, the emphasis o f the study was changed so t h a t the cause o f these c h r o n o l o g i c a l d i f f e r e n c e s and the mecha-nism o f varve g e n e r a t i o n i n Saanich I n l e t c o u l d be s t u d i e d . To do t h i s , the data c o l l e c t e d on the geochemistry and d i -atom assemblages w i t h i n varves from the top 32.5cm o f a core from F i n l a y s o n Arm are presented i n order to determine the sedimentary h i s t o r y o f t h i s p a r t o f Saanich I n l e t . 1.3 A Review of the oceanography o f Saanich I n l e t . Saanich I n l e t i s a f j o r d on the so u t h e a s t e r n c o a s t of Vancouver I s l a n d approximately 24km. long and 7.2km. wide a t i t s widest p o i n t . The bathymetry o f the i n l e t i s c h a r a c -t e r i z e d by a c e n t r a l b a s i n , with a maximum depth o f 234m, and a s i l l a t the mouth r i s i n g to a depth o f 65-75m Fig: 1.2.1 Location of Saanich Inlet showing its bathymetry and indicating coring locations. (adapted from Anderson&Devol.l973) 8 (Fig.1.2.1). The I n l e t has been e x t e n s i v e l y s t u d i e d i n the past, and the f o l l o w i n g short review of i t s oceanography i s based on work published by Herlinveaux (1962), Anderson and Devol (1973), and Hobson (1981). As i s t y p i c a l of f j o r d s i n g e n e r a l , the water c o l -umn of Saanich I n l e t i s c h a r a c t e r i z e d by a surface l a y e r , where seawater i s d i l u t e d by freshwater r u n o f f , separated by a h a l o c l i n e from higher s a l i n i t y water below. However, t h i s I n l e t i s somewhat unusual i n that the major source of the f r e s h water i n the surface l a y e r i s not at the head of the I n l e t , as i s g e n e r a l l y the case i n f j o r d s , but outside the mouth, namely the Cowichan and Fraser R i v e r s (Fig.1.2.2). Since the input of f r e s h water from the Goldstream River a t the head of the I n l e t i s r a t h e r s m a l l , flow i n the surface waters i s only weakly e s t u a r i n e and l a r g e l y d r i v e n by the wind. This c i r c u l a t i o n r e s u l t s i n a net flow out of the I n l e t i n the surface which i s balanced by an i n f l o w o f water from the S t r a i t of Georgia at s i l l depth. This weak c i r c u l a t i o n r e s u l t s i n f u r t h e r s t r a t i f i c a t i o n of the deeper waters i n the c e n t r a l b a s i n and a secondary h a l o c l i n e e x i s t s at or below s i l l depth below which the deep waters are e f f e c t i v e l y i s o l a t e d . The d i s s o l v e d oxygen content of the deep waters i s t h e r e f o r e depleted because the consumption of oxygen by the o x i d a t i o n of organic d e t r i t u s d e r i v e d from primary production near the surface exceeds oxygen r e -plenishment by the c i r c u l a t i o n . The deep waters of the i n l e t 9 consequently contain hydrogen sulphide throughout most of the year. The deep waters are, however, subject to renewal i n so c a l l e d x f l u s h i n g events'. Evidence i s presented i n the l i t e r a t u r e that t h i s occurs annually (Anderson and Devol, 1973). Although no data series longer than 2-3 consecutive years i s avail a b l e , i t i s recognised that the flushing oc-curs c h a r a c t e r i s t i c a l l y during the autumn. C i r c u l a t i o n i n Haro S t r a i t (see F i g . 1.2.1), mixes surface and intermediate waters of the S t r a i t of Georgia with colder, dense water that i s ca r r i e d i n from the upwelling region i n the mouth of the S t r a i t of Juan de Fuca. This produces dense, oxygenated water which moves through Haro S t r a i t following a channel (Fig. 1.2.1) and cascades over the s i l l of the i n l e t . This dense water displaces the bottom water i n the central basin causing i t to r i s e and mix with the surface waters of the i n l e t . Available estimates of the volume of flushing water range from 18-33% of the deep water volume of the i n l e t (Anderson and Devol, 1973). Runoff into the i n l e t i s at a maximum during the winter months following the annual r a i n f a l l pattern of the region. Annual averages at P a t r i c i a Bay on Saanich Inlet are around 81.5cm and maximum monthly r a i n f a l l (around 14 cm.) generally occurs i n December (Herlinveaux, 1962). Freshwater runoff i s derived from three sources. The smallest flow i s from the Goldstream River entering F i n -layson Arm. The largest input comes from the Cowichan River Fig: 1.2.2 Saanich Inlet showing the main rivers, Bamberton and Flnlayson Arm. (after Francois, 1987) 124'W 1 23*W 11 d i s c h a r g i n g i n t o Cowichan Bay 6km no r t h o f the mouth o f the i n l e t and i s a t a maximum i n December. The F r a s e r R i v e r p r o -v i d e s water and sediment d u r i n g i t s % f r e s h e t ' flow, d e r i v e d from snow-melt i n the r i v e r ' s watershed, which i s a t i t s maximum i n June. There are r e p o r t s o f white, s i l t - l a d e n wa-t e r e n t e r i n g the i n l e t a t t h i s time (Herlinveaux, 1962; Francois, 1987) but the r e l a t i v e importance o f t h i s source to the sediments o f the i n l e t has not been c l e a r l y d e f i n e d . T i d e s w i t h i n the i n l e t are q u i t e s m a l l , with an average annual range o f around 1.5m.; however, t i d a l flow over the s i l l i s o f t e n s u f f i c i e n t l y s t r o n g to generate a f r o n t which i s c h a r a c t e r i s e d by hig h b i o l o g i c a l p r o d u c t i o n i n response to mixing and consequent replenishment o f n u t r i -ents i n the s u r f a c e l a y e r (Parsons et al., 1983). B i o l o g i c a l p r o d u c t i o n i n the I n l e t f o l l o w s the b i -modal p a t t e r n common i n temperate and h i g h l a t i t u d e waters, t h a t i s an i n t e n s e s p r i n g bloom f o l l o w e d by a s m a l l e r bloom i n the autumn. Diatoms are the main component o f the phytoplankton throughout most o f the year although f l a g e l l a t e s may dominate d u r i n g the l i g h t - l i m i t e d winter months (Takahashl et al., 1978). The s p r i n g bloom has been shown by Huntley and Hobson (1978) to c o n s i s t o f two d i s t i n c t peaks. The f i r s t bloom c o n s i s t s o f T h a l a s s i o s i r a S P P . . mainly T.nordensWiLflj,!* T . a e s t i v a l i s and T . p a c i f i c a . and i t i s r e -duced by zooplankton g r a z i n g which both decreases the popu-l a t i o n and r e l e a s e s n u t r i e n t s i n t o the water. T h i s a l l o w s a 12 second bloom to occur which i s dominated by Chaetoceros S P P - . mainly C tdidvmus and C.radicans. and by Skeletonema costatum. This second bloom i s protected from g r a z i n g be-cause the herbivore p o p u l a t i o n i s now subject to predation by the medusa P h l a l i d l u m areaarium. Primary production i s g e n e r a l l y confined to the surface 5-15m. because of s t r a t i f i c a t i o n of the water c o l -umn. However, Takahashi et al. (1977) have shown th a t d i s -r u p t i o n of the s t r a t i f i c a t i o n by wind-driven upwelling i n -troduces n u t r i e n t s i n t o the surface r e s u l t i n g i n short blooms of phytoplankton during the summer months. These oc-c a s i o n a l summer blooms f o l l o w the general species succession, although f a l g e l l a t e s may dominate some of the l a t e summer blooms. Resting spores, e s p e c i a l l y those of the Chaeto- ceros group, are a common feature of the phytoplankton and sediments (Harrison, 1983). Their germination r a t e i n s h a l -low waters i s high and they probably seed the summer blooms (Hollibaugh et al., 1981). 1 .4 G e o l o g i c a l summary of the Saanich I n l e t area. The f o l l o w i n g summary i s based on Clapp (1912; 1913) and / f u l l e r (1980). F i g . 1.3.1 shows a sketch map of the main g e o l o g i c a l features of the area. The o l d e s t rocks outcropping i n the area belong to the pre-Permian S i c k e r Group. This c o n s i s t s of flow and ex-p l o s i v e v o l c a n i c rocks, i n t r u s i v e m i c r o d i o r i t e s and sedimen-13 Fig: 1.3.1 Geological sketch map of Saanich Inlet. 14 t a r y r o c k s which have a l l been e x t e n s i v e l y metamorphosed to s c h i s t grade. The v o l c a n i c rocks are mostly a n d e s i t e s and the sediments were probably o r i g i n a l l y t u f f s . The i n t r u s i v e rocks are q u a r t z f e l d s p a r porphyry and g r a n o d i o r i t e bodies. The T r i a s s i c Karmutsen v o l c a n i c s , o r i g i n a l l y c a l l e d the Vancouver V o l c a n i c s , are b a s i c a n d e s i t e s and have a l s o been h i g h l y metamorphosed. In the v i c i n i t y o f Saanich I n l e t , a b r e c c i a t e d form occurs which has a higher f e l d s p a r content and a l s o c o n t a i n s k a o l i n i t e . The J u r a s s i c ^metamorphic complex' c o n s i s t s o f a d i o r i t e / q u a r t z d i o r i t e g n e i s s b a t h o l i t h . I t c o n t a i n s ande-s i n e and hornblende, with a c c e s s o r y q u a r t z , magnetite and t i t a n i t e . Above these are the I s l a n d I n t r u s i v e s , the p r i n c i -p a l i n t r u s i v e rock o f southern Vancouver I s l a n d , and t h i s group i s r e p r e s e n t e d here by the Saanich g r a n o d i o r i t e . I t c o n t a i n s p l a g i o c l a s e , o r t h o c l a s e , some hornblende and mi-c r o p e r t h i t e with a c c e s s o r y b i o t i t e , magnetite, t i t a n i t e , k a o l i n i t e and p y r i t e . The youngest bedrock o f the area c o n s i s t s o f the Cretaceous r o c k s o f the Nanaimo Group, comprising o f con-glomerates, sandstones and s h a l e s . The topography o f the western s i d e o f Saanich I n -l e t i s steeper and bedrock outcrops are common. In c o n t r a s t , the e a s t e r n s i d e o f the I n l e t i s more subdued and the bedrock o f the Saanich p e n i n s u l a r i s g e n e r a l l y covered by g l a c i a l d r i f t . 15 CHAPTER 2; METHODS. 2.1 Core C o l l e c t i o n and sample p r e p a r a t i o n . The sediments of the c e n t r a l b a s i n of Saanich I n -l e t are g e n e r a l l y r e f e r r e d to as b l a c k , varved, diatomaceous c l a y e y - s i l t s (Matsumoto and Wong, 1977), an xodious ooze' reported by Clapp (1913). In a d d i t i o n , the l a c k of s i g n i f i -cant b i o t u r b a t i o n because of the anoxic nature of the s t i l l bottom waters, and the d i a t o m - r i c h and o r g a n i c - r i c h nature of the d e p o s i t s , causes the sediments to be very f l u i d u n t i l depths are reached where compaction has a s i g n i f i c a n t e f f e c t upon c o n s o l i d a t i o n . These were important c o n s i d e r a t i o n s i n planning the sampling, s i n c e the development of a chronology, b a s i c to the i n t e r p r e t a t i o n of any geochemical or f o s s i l trends, r e q u i r e d t h a t the sediment/water i n t e r f a c e be c o l l e c t e d . In order to preserve the i n t e r f a c e , c o r i n g was c a r r i e d out us-ing a lm.x lBcm.xl5cm. f r e e l y - v e n t e d Hasten Box c o r e r . Pre-vious s t u d i e s i n Saanich I n l e t by U.B.C personnel had ob-t a i n e d a sediment i n t e r f a c e s u c c e s s f u l l y with t h i s equip-ment. Coring was c a r r i e d out i n F i n l a y s o n Arm,(see F i g . 1.2.1 f o r l o c a t i o n s of CPIII and CPIV), an area of the i n l e t expected to be minimally d i s t u r b e d by previous bottom 16 sampling. One core was a l s o c o l l e c t e d o f f the Bamberton cement works i n the hope t h a t a carbonate i n c r e a s e might p r o v i d e a time marker c o i n c i d e n t with the begin n i n g o f q u a r r y i n g a c t i v i t y , but t h i s core has not been sampled. A t o t a l o f seven box cores were c o l l e c t e d . Table I D e t a i l s o f Recovered Cores. DATE CORE NO. RECOVERED LENGTH DEPTH POSITION 9/8/85 102 cm 208 m 123 32 17W CPI 48 31 40N 8/10/85 107 cm 204 m 123 32 16W C P U 48 31 40N 10/10/85 69 cm 203 m 123 32 18W CPI I I 48 31 32N 4/11/85 54 cm 202 m 123 32 48W CPIV 48 32 40N 7/11/85 74 cm 208 m 123 32 44W CPV 48 31 48N 16/12/85 86 cm 224 m 123 30 46tf CPVI 48 35 24N 18/12/85 41 cm 203 m 123 32 42W CPVI I 48 32 42N C o r i n g was c a r r i e d out from Vector and the core s were f r o z e n on board. F r e e z i n g was achieved by p l a c i n g the c o r e r u p r i g h t i n a t a l l b a r r e l c o n t a i n i n g 300 l i t r e s o f i s o p r o p y l a l c o h o l c o o l e d to around -60°C by the a d d i t i o n o f 100 kg. o f dry i c e . The core was allowed to f r e e z e f o r 3-4hrs. a f t e r which time both ends o f the c o r e r were removed and the box s e c t i o n warmed with hot water. T h i s thawed the o u t s i d e o f the sediments and allowed the f r o z e n core to be removed. The cores were wrapped i n p l a s t i c and t r a n s p o r t e d to Vancouver i n an i n s u l a t e d box. In Vancouver they were s t o r e d i n a c h e s t f r e e z e r a t -10 <>C. Only cores CPIII and CPIV were sampled. In cores CPI-CPIII the recovered i n t e r f a c e was l o s t because o f expan-s i o n on f r e e z i n g or i n s u f f i c i e n t a l c o h o l - d r y i c e mixture; however, core CPIII was sampled because a prominent l a y e r near i t s top appeared to correspond with a l a y e r a t the base of CPIV. CPV c o n t a i n e d a preserved i n t e r f a c e , but X - r a d i o g -raphy o f t h i s core showed t h a t the laminae were d i s t u r b e d and i t i s thought t h a t t h i s was caused by the c o r e r doors. Cores CPVI, c o l l e c t e d o f f the cement works a t Bamberton, and CPVII both have preserved i n t e r f a c e s but were not sampled. The c o r e s were s e c t i o n e d , u s i n g a stone-masons band saw a t Chandler Memorials, Vancouver, such t h a t the outer edges o f the core were removed and the c e n t r a l s e c t i o n p r eserved f o r sampling. The c e n t r a l s e c t i o n s measured ap-p r o x i m a t e l y 14cm x 7cm x r e c o v e r e d l e n g t h o f the core. X-radiographs were made of these s e c t i o n s i n order to determine t h e i r i n t e r n a l s t r u c t u r e s and to allow the X-r a y p l a t e s to be used as a guide d u r i n g sampling. The s e c -t i o n s were p l a c e d on top o f EKC "AA" f i l m p l a t e s (16x20") and exposed to 180 Kv X-rays a t a d i s t a n c e o f 170 cm f o r 90 seconds. Fig.2.1.2 shows reduced X-ray images taken of the P L A T E I x * r a d i o g r a p h of the s a m p l e d c o r e s . -rtvo - — -18 t o li-tl m 5.J-two sampled c o r e s . X - r a y i n g was performed by I n d u s t r i a l Non-d e s t r u c t i v e T e s t i n g L t d . i n Vancouver. On the b a s i s o f the X-ray images obt a i n e d , f u r t h e r work, was c o n c e n t r a t e d on cores CPIII and CPIV. Although the i n t e r f a c e o f core CPIII had been l o s t , the p a t t e r n o f the varves a t the top of the r ecovered s e c t i o n appeared to match t h a t a t the base o f core CPIV, a core with the s e d i -ment/water i n t e r f a c e i n t a c t . I t was hoped t h a t sampling both would al l o w an extended time p e r i o d to be s t u d i e d . Subsequent s t u d i e s o f the diatom f l o r a o f some prominent l a y e r s i n both c o r e s showed t h a t they were not, i n f a c t , the same l a y e r s and, consequently, t h a t i t was not p o s s i b l e to c o n s t r u c t a longer r e c o r d . The study r e p o r t e d here c o n c e n t r a t e s on core CPIV. An 2.5cm wide s t r i p down the l e n g t h o f the c e n t r a l s e c t i o n was p reserved f r o z e n as a r c h i v e m a t e r i a l . The r e -maining p a r t o f the c e n t r a l s e c t i o n was sampled l a y e r by l a y e r i n a w a l k - i n f r e e z e r a t the I n s t i t u t e o f Ocean S c i -ences, P a t r i c i a Bay, B.C. Sampling was s t a r t e d a t the bottom of the p r e s e r v e d s e c t i o n s and the l a y e r s were scraped u s i n g g l a s s microscope s l i d e s with the s c r a p i n g s being caught on a c l e a n g l a s s p l a t e . The s c r a p i n g s were s t o r e d f r o z e n i n p l a s -t i c p o t s . Every care was taken to f o l l o w the l a y e r s as c l o s e l y as p o s s i b l e . I t was found t h a t the l a y e r s c o u l d be d i s t i n g u i s h e d both from t h e i r c o l o u r and by t h e i r f r o z e n t e x t u r e . I t was a l s o noted t h a t the dark l a y e r s i s s u e d a 20 s t r o n g s m e l l o f hydrogen s u l p h i d e . R e c o g n i t i o n o f these c h a r a c t e r i s t i c s allowed sampling i n the top 15 cm. of the core although the X-ray images showed i n d i s t i n c t l a y e r s . In core CPIV, notes taken d u r i n g sampling i n d i c a t e t h a t the laminae were becoming i n d i s t i n c t and thus harder to f o l l o w from sample 70 upwards to the preserved i n t e r f a c e . During sampling, an attempt was made to d i s c a r d the i n t e r f a c e be-tween l a y e r s so t h a t the samples c o l l e c t e d r e p r e s e n t e d the tr u e c h a r a c t e r i s t i c s o f each i d e n t i f i e d l a y e r . Measurements were taken down the c e n t r e o f the core before and a f t e r each l a y e r was scraped to al l o w each sample to be matched with a p a r t i c u l a r l a y e r on the X-ray p l a t e s . Before each l a y e r was scraped, a small p l u g o f the sediment was removed u s i n g a N c o r k - b o r e r T h e s e samples were c a r e f u l l y c l e a n e d so t h a t they were r e p r e s e n t a t i v e o f o n l y one l a y e r and were c o l l e c t e d so t h a t the diatom assemblage c o u l d be s t u d i e d . They were kept f r o z e n i n g l a s s v i a l s u n t i l prepared i n the l a b o r a t o r y . In Vancouver, the s c r a p i n g s were allowed to a i r -dry and were then ground by hand i n agate and weighed. Any l a r g e wood fragments were removed to a v o i d erroneous v a l u e s i n the d e t e r m i n a t i o n o f o r g a n i c carbon. The d r i e d samples ranged i n weight from 10.5 g. to 2.2 g. with a mean o f 3.5 9-21 2.2 Geochronoloav u s i n g a»°Pb. Dating was c a r r i e d out by determining the a i o P o a c t i v i t y o f the sediments by alpha-spectrometry and assuming e q u i l i b r i u m with a l o P b (ttt= 22.2yrs.). An e x t e n s i v e review of geochronology u s i n g a i o P b i s found i n Robbins (1978). Sample p r e p a r a t i o n c o n s i s t e d o f d i g e s t i n g the sediments i n h y d r o f l u o r i c and n i t r i c a c i d s together with a y i e l d t r a c e r o f a o B P o , p l a t i n g the a*°Po onto n i c k e l d i s c s i n an a c i d i c s o l u t i o n (HC1), and cou n t i n g the d i s c s by «-spectrometry. The method used i s d e s c r i b e d by Smith and Mai ton (1980) and i s based on t h a t p u b l i s h e d by Flynn (1968). The on l y d i f f e r e n c e between the p u b l i s h e d methods and those used i n t h i s study i s the s u b s t i t u t i o n o f n i c k e l f o r s i l v e r d i s c s . N i c k e l has been found to have very s i m i l a r p l a t i n g e f f i c i e n c i e s to s i l v e r and i s c o n s i d e r a b l y cheaper (J.N Smith, p e r s . comm.). Counting o f a*°Po and a o e P o a c t i v i t i e s was p e r -formed on an ORTEC 567a Alpha spectrometer u s i n g ORTEC s u r f a c e b a r r i e r d e t e c t o r s with an area o f 450mma. Samples were counted f o r 24hrs. An extended d e s c r i p t i o n o f the method used and an estimate o f p r e c i s i o n (± 6.33% RSD 2a) can be found i n Appendix A. 22 2.3 Determination o f bulk mineralogy and the major and minor element c o n c e n t r a t i o n s bv X-rav a n a l y s i s . The bulk mineralogy o f the samples was determined q u a l i t a t i v e l y u s i n g X-ray d i f f r a c t i o n on a P h i l i p s PW 1729 generator/goniometer and a P h i l i p s PW 1710 d i f f r a c t o m e t e r c o n t r o l u n i t . Raw sediment samples were pressed i n t o d i s c s with a backing o f i n s t a n t c o f f e e and were scanned from 3.0-35.0 °26 a t a scanning speed of 0.01 °26/s. and a time con-s t a n t o f 3 seconds. The elemental composition o f the samples was de-termined by X-ray f l o u r e s c e n c e u s i n g a P h i l i p s PW 1400 spec-trometer. Determinations were made o f the major elements: S i , A l , Fe, Mg, Ca, K, P, T i and S, and the minor elements Ba, Cu, Cr, Mo, N i , Pb, Sr, Rb, V, Y, Zn, and Zr. Mn and Na are determined i n both the major and minor element a n a l y t i -c a l programs s i n c e some sodium i s l o s t as v o l a t i l e s d u r i n g the f u s i o n process used i n sample p r e p a r a t i o n f o r major e l e -ment a n a l y s i s , and s i n c e manganese i s p r e s e n t i n a n o x i c s e d -iments i n such low c o n c e n t r a t i o n s , t y p i c a l l y around 500-600 ppm. The v a l u e s f o r these elements r e p o r t e d i n t h i s study are those d e r i v e d from the minor element a n a l y s i s program. Sulphur and Mo were determined u s i n g separate programs be-cause the i n t e r n a t i o n a l rock standards used f o r c a l i b r a t i o n have low c o n c e n t r a t i o n s o f these elements and t h i s r e q u i r e d t h a t s y n t h e t i c standards be made. Co b a l t and Pb were a l s o measured i n the minor e l e -ment measuring program; t h e i r c o n c e n t r a t i o n s were very low 23 (5-15ppm) and the f a c t t h a t the Co Ka l i n e i s very c l o s e to the Fe KB l i n e and t h a t the Pb LJ3 l i n e i s o f low i n t e n s i t y rendered the d e t e r m i n a t i o n s o f these elements somewhat un-c e r t a i n . The r e s u l t s o b t a i n e d f o r Co are not r e p o r t e d ; how-ever, the Pb r e s u l t s are r e p o r t e d i n Chapter 3 i n conjunc-t i o n with the carbonate data. The major elements were determined u s i n g fused g l a s s d i s c s and the t r a c e and minor elements were determined on pressed powder p e l l e t s . A f u l l d e s c r i p t i o n o f the methods used i n sample p r e p a r a t i o n and a n a l y s i s , together with e s t i -mates o f p r e c i s i o n , are p r o v i d e d i n Appendix B. S a l t c o r r e c t i o n s were d e r i v e d from the c h l o r i n e c o n c e n t r a t i o n s o f the samples as determined by d i s s o l v i n g the s a l t i n d i s t i l l e d water and t i t r a t i n g the c h l o r i d e a g a i n s t s i l v e r n i t r a t e . A f u l l d e s c r i p t i o n o f the method used i s p r o v i d e d i n Appendix C together with the f a c t o r s used to c o r r e c t the element c o n c e n t r a t i o n s . 2.4 Determinations o f carbon, n i t r o g e n and carbonate. T o t a l carbon and n i t r o g e n d e t e r m i n a t i o n s were done u s i n g an automated C a r l o - E r b a CHN a n a l y s e r which measures Na, COa and HaO produced by combustion gas chromatography. A f u l l d e s c r i p t i o n of the method used and a p r e c i s i o n estimate (±0.73% f o r carbon and ±2.6% f o r n i t r o g e n , RSD,2o) are r e -ported i n Appendix D. 24 Carbonate carbon was determined by coulometry a f -t e r d i g e s t i o n i n 10% HCl. A f u l l d e s c r i p t i o n o f t h i s method i s a l s o found i n Appendix D. 2.5 Sample p r e p a r a t i o n and c o u n t i n g o f diatom f r u s -t u l e s . The o r i g i n a l i n t e n t i o n o f t h i s work r e q u i r e d an a n a l y s i s o f the diatom and s i l i c o f l a g e l l a t e f o s s i l s p r e -served i n the sediments. I t was hoped t h a t any trends which might be d i s c o v e r e d i n the assemblage c o u l d be dated and c o r r e l a t e d with h i s t o r i c a l r e c o r d s of c l i m a t i c and oceano-g r a p h i c data. The problems encountered with the d a t i n g meant t h a t the diatom f l o r a needed to be counted f o r another r e a -son. I t was necessary to determine i f the varves were indeed seasonal and whether the samples c o l l e c t e d from the top o f the core r e f l e c t e d the seasonal d e p o s i t i o n . To t h i s end samples were c o l l e c t e d as p r e v i o u s l y d e s c r i b e d and they were cl e a n e d , mounted on microscope s l i d e s and counted u s i n g methods d e s c r i b e d i n Appendix E. I t was decided to count groups o f diatoms which should show a d i s t i n c t seasonal s i g n a l : T h a l a s s l o s l r a S P P . . Chaetoceros S P P . and Skeletonema costatum r e p r e s e n t i n g the s p r i n g bloom and summer p r o d u c t i o n , while b e n t h i c s p e c i e s , such as P a r a l i a s u l c a t a , and pennates w i t h i n the N a v i c u l a . N l t z c h i a and Grammatophora genera were counted as a group which might r e p r e s e n t r u n - o f f and r e s u s p e n s i o n a c t i v i t y which i s thought to be c h a r a c t e r i s t i c o f the winter. These groups were s e l e c t e d from s t u d i e s o f diatom m a t e r i a l r ecovered from sediment t r a p s moored i n Saanich I n -l e t as p a r t o f an ongoing UBC study. Some o f the r e s u l t s o f the diatom r e c o r d f o r 1984-1985 t r a p m a t e r i a l are g i v e n by Sancetta and Calvert (1987, i n p r e s s ) . 26 CHAPTER 3; RESULT?. A c e r t a i n p r o t o c o l i s f o l l o w e d i n the p r e s e n t a t i o n of the r e s u l t s i n t h i s chapter. Since the core was c o l l e c t e d i n e a r l y November 1985 i t was assumed t h a t the sample taken from the sediment/water i n t e r f a c e (No:86) r e p r e s e n t s summer p r o d u c t i o n . However, i t w i l l be shown i n t h i s chapter t h a t the i n t e r f a c e recovered i n t h i s core may not be the t r u e sediment/water i n t e r f a c e , t h a t the uppermost p a r t o f the sediment column may have been l o s t and t h a t the sampled s e c -t i o n c o n t a i n s two d i s t i n c t sediment types. The core was sampled from the base upwards and t h i s l e d to the l i g h t l a y e r s being g i v e n EVEN numbers and to the dark l a y e r s being g i v e n ODD numbers. The topmost sample, number 86, was thought to be a l i g h t l a y e r d e p o s i t e d i n summer 1985. An annual varve i s taken to be a l i g h t l a y e r and the dark l a y e r above i t . The element p r o f i l e s presented i n t h i s chapter are annotated with an estimate o f p r e c i s i o n as the 2a RSD e r r o r a s s o c i a t e d with the mean value and the l i g h t and dark sam-p l e s are i n d i c a t e d . Ixi Chronology of the core bv *»QPb. Table I I p r e s e n t s the a i ° Pb a c t i v i t i e s found i n core CPIV. The measured v a l u e s a t the top of t h i s core are s l i g h t l y lower than those recorded i n the I n l e t by p r e v i o u s workers . For example, Bruland (1974), u s i n g beta c o u n t i n g Table I I R e s u l t s o f 210 Pb. A n a l y s i s . Core CPIV. CORRECTED DPM/G. SAMPLE WEIGHT(g) DEPTH(cm) DEPTH* 210 Pb# 86 1.004 0 0 10.1+.29 85 1.001 3.8 6.2 12.1+.37 83 1.000 7.5 15.4 8.6+.29 81 1.005 7.7 15.6 5.7+.2 79 1.001 9.8 22.1 4.2+.11 75 1.007 11.8 28. 2 3.8+.17 73 1.004 13.3 33.3 2.9+.15 71 1.001 15.4 41.0 1.7+.13 68 1.001 18. 3 51.4 1.6+.12 63 1.005 19.9 57.5 1.1+.12 57 1.006 24. 3 74.8 1.3+.13 53 1.009 29.7 96. 3 1.2+.13 49 1.001 32.9 107.7 1.1+.22 * Depth c o r r e c t e d f o r compaction u s i n g p o r o s i t y data from Matsumoto & Hong (1977). # dpm/g. EXCESS 210Pb. 1.2dpm/g s u b t r a c t e d , Bruland (1974). Values are S a l t Corrected.+ 2 sigma. E r r o r e s t i m a t e s are c a l c u l a t e d from ORTEC output and i n c l u d e c o r r e c t i o n f o r y i e l d . of a i o B i , found v a l u e s o f 14.9-15.9 dpm/g i n the s u r f a c e sediments, while Matsumoto and Wong (1977), a l s o u s i n g the a*°Bi method, found v a l u e s o f 15.7-21.7dpm/g i n the top 7cm of a core from S q u a l l y Reach. T h i s o b s e r v a t i o n might be e x p l a i n e d by d i f f e r e n t s e d i m e n t a t i o n r a t e s a t the d i f f e r e n t c o r i n g l o c a t i o n s , or i t might i n d i c a t e the l o s s of sediment from the top o f t h i s c o r e . Carpenter and Beasley (1981), u s i n g the same method as t h a t used i n t h i s study, r e p o r t a s u r f a c e value o f 10.7dpm/g a t a s t a t i o n i n F i n l a y s o n Arm; however, they a t t r i b u t e the low v a l u e s to incomplete i s o t o p e p r o f i l e s . I t w i l l be shown i n s e c t i o n 3.3 t h a t the carbonate data f o r t h i s core a l s o i n d i c a t e s t h a t sediment has been l o s t from the top o f t h i s c o r e . Fig.3.1.1 p r e s e n t s the a i o P b data i n g r a p h i c a l form; i t i n c l u d e s an i n d i c a t i o n of the 22.2yr. h a l f l i f e o f a i o P b , and the dates o b t a i n e d by varve c o u n t i n g assuming the preserved i n t e r f a c e to be 1985. I t w i l l be shown i n s e c t i o n 3.3 t h a t t h i s assumption i s probably f a l s e , t h a t the t r u e i n t e r f a c e has been l o s t and t h a t the core top appears to be sediments which accumulated between 1960-1963. However, i n both cases there i s c l e a r l y a major d i s c r e p a n c y between dates determined from the a i o P b a c t i v i t y and those from varve counts. The a*°Pb p r o f i l e (Fig.3.1.1) shows no i n d i c a t i o n o f mixing or d i s t u r b a n c e o f the sediment column; however, o b s e r v a t i o n s d e r i v e d from the major element chemistry ( s e c t i o n 3.4) i n d i c a t e t h a t there i s a d i f f e r e n t sediment type i n the top 15cm o f the core and i t w i l l be 29 Fig:3.1.1 Profile of 210Pb activity Excess 210 Pb. ( d p m / g . ) 0.00 5.00 10.00 0.0 10.0 H o CD ro o 20.0 H > 30.0 i i i i i i i i I i i i i i i i i i L i i i 81:1982 > CO l _ >» C M C M C M . CL o * C M >/ 71:1977 CORE CPIV. COLLECTED 11/4/85. Flnlayson Arm, Saanich Inlet. x D a t e s are derived from varve counts A > 49:1966 30 shown i n t h i s s e c t i o n t h a t t h i s change i n sediment i s probably accompanied by a change i n sedimentation r a t e . The d i s c r e p a n c y between the 2 1 ° P b p r o f i l e and the varve counts made i t necessary to check the v a l i d i t y o f the a i o P b p r o f i l e . To do t h i s some samples were analysed f o r 1 3 T C s a t the Lamont Doherty G e o l o g i c a l Observatory. These samples were measured by gamma spectrometry u s i n g an ORTEC GWL-90210 spectrometer with w e l l - t y p e i n t r i n s i c germanium d e t e c t o r s ; d e t a i l s o f the sample p r e p a r a t i o n , c a l i b r a t i o n and e s t i m a t e s o f accuracy are not a v a i l a b l e . Samples were s e l e c t e d based on both the a*°Pb chronology and on the varve c o u n t i n g and assuming the i n t e r -face to be 1985. The aim o f t h i s s e l e c t i o n was to d e f i n e the 1963 peak o f xbomb» caesium (Robbins and Edglngton, 1975). The r e s u l t s are presented i n Tables I I I and IV. 31 Table I I I Comparison between a i o P b Chronology and xmrCs A c t i v i t y . SAMPLE NO. &DEPTH "<>Pb DATE l s r rCs ACTIVITY 83 6.4cm 80 9.5cm 78 10.9cm 76 11.5cm 1968 1963 1958 1953 190±50 dpm/kg. 150±50 dpm/kg. <20±50 dpm/kg. <20±50 dpm/kg. Table IV Comparison between Varve Count dates and i a T C s A c t i v i t y . SAMPLE NO. &DEPTH VARVE DATE *» TCs ACTIVITY 50 32.2cm. 40 35.7cm. 30 40.0cm. 1968 1963 1958 <20±50 dpm/kg. 86±56 dpm/kg. 67±55 dpm/kg, The * 3 TCs a c t i v i t i e s seem to be c o n s i s t e n t with the a i o P b chronology r a t h e r than with the varve counts. However, i t does appear t h a t the peak o f * a rCs a s s o c i a t e d with 1963 was not c l e a r l y d e f i n e d . Carpenter and Beasley (1981) r e p o r t s u r f a c e 1 S 9 TCs v a l u e s o f 412dpm/kg i n F i n l a y s o n Arm which r i s e to 800dpm/kg a t 2-4cm. Robbins and Edgington (1975) r e p o r t v a l u e s o f around 370dpm/kg f o r the 1963 peak i n Lake Michigan. The sample (sample 83) thought to r e p r e s e n t 1968 by a i o P b chronology has more i a T C s than t h a t g i v e n the a*°Pb date o f 1963. T h i s o b s e r v a t i o n l e a d s to the 32 c o n c l u s i o n t h a t the top o f the co r e , assumed to be the sediment/water i n t e r f a c e i n order to d e r i v e the a i o P b dates, i s not the i n t e r f a c e , and can o n l y mean t h a t some sediment has been l o s t from the core top. T h i s c o n c l u s i o n i s supported by the lower a i o P b a c t i v i t y compared to other data from Saanich I n l e t and by carbonate data presented i n s e c t i o n 3.3. More d e t a i l e d sampling would be r e q u i r e d to de-termine the s i g n i f i c a n c e o f the s l i g h t i n c r e a s e i n l a , TCs a c t i v i t y lower i n the core (Table I V ) . Since the o b j e c t i v e s o f t h i s study r e q u i r e d an a c -cu r a t e chronology, the study was r e f o c u s e d on the cause o f the d i s c r e p a n c y between the a i o P b chronology and t h a t o f the varve counts. D e t a i l e d geochemical analyses and counts o f the major diatom groups were c a r r i e d out on the top of core CPIV. The data r e p o r t e d are the r e s u l t s o f work on samples 86 (the sediment/water i n t e r f a c e ) to 50 (32.2cm), with the e x c e p t i o n o f the * B TCs samples based on varve counts which were taken from lower i n the core (see Table I V). 3.1.1 C a l c u l a t i o n o f sediment accumulation r a t e . The c a l c u l a t i o n o f both the sedime n t a t i o n r a t e (cm/year) and the sediment accumulation r a t e (g/cm*/year) r e q u i r e p o r o s i t y data i n order to take account o f compaction to d e r i v e a c o r r e c t e d depth. P r e c i s e d e t e r m i n a t i o n o f p o r o s i t y r e q u i r e s the c a r e f u l measurement o f pore water volume and t h i s was not p o s s i b l e on t h i s core because o f the n e c e s s i t y to f r e e z e i t on r e c o v e r y i n order to preserve the 33 F i g : 3.1.2 CHLORIDE CONTENT. A n n o t a t i o n s s h o w w a t e r c o n t e n t s . 86.8 p 1 | | U 1 1 1 1 1 11 13 15 17 19 21 % CHLORIDE * N u m b e r s r e p r e s e n t wa te r c o n t e n t s c a l c u l a t e d for a b o t t o m wate r s a l i n i t y of 3 17... 34 varves. However, the c h l o r i n e content of the d r i e d samples c o u l d be used to determine the amount o f seawater i n a g i v e n sample and thus a l l o w the c a l c u l a t i o n o f p o r o s i t y . The c h l o -r i n e p r o f i l e o b t a i n e d i s presented i n Fig.3.1.2. Two i n t e r p r e t a t i o n s o f t h i s p r o f i l e are p o s s i b l e . F i r s t l y , i t c o u l d i n d i c a t e a m i g r a t i o n o f water i n t o the c e n t r a l s e c t i o n o f the core as a r e s u l t o f dewatering a t the s u r f a c e b e f o r e f r e e z i n g . Since the sediments are known to be very f l u i d , t h i s seemed a reasonable assumption s i n c e the f r e e z i n g process c o u l d i n f l u e n c e the p o r o s i t y o f the sediments. T h i s i n t e r p r e t a t i o n meant t h a t the c h l o r i n e p r o f i l e c o u l d not be used to c a l c u l a t e p o r o s i t y and e s t i m a t e s o f the s e d i m e n t a t i o n and accumulation r a t e s were ob t a i n e d u s i n g the p o r o s i t y data i n Saanich I n l e t r e p o r t e d by Matsumoto and Hong (1977). However, once the data on the major element chem-i s t r y became a v a i l a b l e and i t appeared t h a t there was a d i f -f e r e n t sediment type i n the top 15cm o f the core (see s e c -t i o n 3 . 4 ) , i t became a p o s s i b l i t y t h a t the c h l o r i n e p r o f i l e d i d , i n f a c t , r e f l e c t the t r u e p o r o s i t y o f these sediments. The decreased c h l o r i n e c ontents a t the top o f the core were c o i n c i d e n t with a d i s t i n c t sediment type, c o n t a i n i n g higher Fe and T i f o r example, and probably has a d i f f e r e n t p o r o s i t y . T h i s i n t e r p r e t a t i o n i s supported by the marked d i f f e r e n c e s i n the c h l o r i n e content between the l i g h t and dark samples lower i n the core which i m p l i e s t h a t the water contents o f d i s c r e t e l a y e r s have been preserved. I t i s t h e r e f o r e u n l i k e l y t h a t a s i g n i f i c a n t amount o f water m i g r a t i o n has occ u r r e d . Hence, the sample water contents can be used to determine p o r o s i t y . Estimates o f sedimentation r a t e s are made u s i n g the two methods. 3.1.2 Determination o f the sedimentation r a t e u s i n g o o r o s l t v data from Matsamoto and Vona (1977). In order to- estimate the mass accumulation r a t e , the p o r o s i t y data from Matsumoto and Wong (1977) have been used. The method f o r c a l c u l a t i n g the sedimen t a t i o n r a t e and the accumulation r a t e can be found i n Bobbins and Edgington (1975) and Matsamoto and Wong (1977). The data used come from a core a t t h e i r s t a t i o n SI-3, s i t u a t e d j u s t to the nort h o f core CPIV i n S q u a l l y Reach, (see Fig.1.2.1) The sample depth was f i r s t c o r r e c t e d f o r com-p a c t i o n u s i n g ; f z = _1 [ z ( l - * ' ) + ( * z z * o j l (1) L J3 J where *=. = i n t e r f a c e p o r o s i t y = 0.984 #• = estimated p o r o s i t y a t f i n a l compaction^.933. £ = cons t a n t = 0.109 z = depth #« = (*=,-*• )e~*" +••«= p o r o s i t y a t depth z The p l o t o f c o r r e c t e d depth a g a i n s t excess a i o P b (Fig.3.1.3) g i v e s the sedimentation r a t e by the slope o f the r e g r e s s i o n l i n e . The r a t e o b t a i n e d f o r core CPIV i s 1.55  cm/vear. T h i s s e d i m e n t a t i o n r a t e can then be used to c a l c u l a t e an accumulation r a t e as f o l l o w s ; Fig:3.1.3 Cor rec ted depth against e x c e s s 210Pb 10 q Q _ 3 r o 0 1 0 TJ cr 10 -2 . 0. CORE CPIV. COLLECTED 11/4/85 FinloyBon Arm, Saanich Inlet. R=0.90 Gradient = - 0 . 0 2 . 1,55 cm/y r S . d l m . n t a t l o n Rt t*e~ 210Pb dacay c o n t l a n l • 0.03 1 1 I I I I I I I I I | I I I I I I I I I | I 1 0 50.0 100.0 Corrected Depth, (cm) 37 w = S„(l - *o)p- (2) where p, = g r a i n d e n s i t y = 2.06±0.05 g/cm 3 *o = s u r f a c e p o r o s i t y = 0.984 So = sedimentation r a t e a t s u r f a c e = 1.55 cm/yr. An accumulation r a t e o f 51 ma/cm«/vr-l was ob-t a i n e d . T h i s value agrees with other r a t e s i n the l i t e r a t u r e f o r Saanich I n l e t , and i t confirms the t r e n d o f a de c r e a s i n g r a t e from the mouth to the head o f the i n l e t . Table V Sediment Accumulation Rates i n Saanich I n l e t . STATION Accum.Rate REFERENCE NUMBER mg/cm«/yr-l SI-9 257 R.Francois (pers. comm.) SI-7 270 Matsumoto and Wong (1977) G 144 Carpenter and Beasley (1981) I 90 Carpenter and Beasley (1981) SI-3 94 Matsumoto and Wong (1977) SN 0.8 95 R.Francois (pers.comm) CPIV 51 T h i s Study 3.1.3 C a l c u l a t i o n o f p o r o s i t y from the measured c h l o -r i n e c o n c e n t r a t i o n s . The r e s u l t s o f the c h l o r i d e d e t e r m i n a t i o n , p e r -formed by t i t r a t i o n a g a i n s t AgNOa, were converted to a weight % water content t a k i n g 314a. as the s a l i n i t y o f the bottom water i n Saanich I n l e t (M.Soon pers.comm; Matsumoto 38 Table VI Results of Ca lcu la t ions using Chlor ide as an ind ica tor of true poros i ty . SAMPLE DEPTH WATER SEDIMENT WEIGHT (wt.%) DRY WT (g)WATER (g) POROSITY 86 0 86. 8 1.004 6.602 0.93 85 3.8 86. 6 1.001 6.469 0.93 83 7.5 86.7 1.000 6.519 0.93 81 7.7 88. 1 1.005 7. 440 0.94 79 9.8 89. 1 1.001 8. 182 0 . 94 75 11.8 89.4 1.007 8.493 0.94 73 13.3 90.5 1.004 9. 564 0.95 71 15.4 90.0 1.001 9.009 0. 95 68 18. 3 92. 2 1.001 11.832 0.96 63 19.9 90.5 1.005 9.574 0.95 57 24. 3 89. 0 1.006 8. 139 0.94 53 29.7 88.4 1.009 7. 689 0.94 Weight of Water and Porosi ty ca lcu la ted using a Saanich bottom water densi ty o f : 1.02 g/cm3 and a sediment gra in density o f : 2.06 g/cm3. Both values are given by Matsumoto and Wong (1977). 39 and Wong, 1977). These values are shown on Fig.3.1.2. From the water contents i t i s p o s s i b l e to c a l c u l a t e the weight of water t h a t would be a s s o c i a t e d with the mass o f dry sediment used to determine the 2 l o P b a c t i v i t y and, u s i n g a d e n s i t y o f Saanich I n l e t bottom water o f 1.02 g/cm a and a g r a i n d e n s i t y f o r Saanich I n l e t c e n t r a l b a s i n sediments o f 2.06±0.05 g/cm 3 (both v a l u e s g i v e n by Mat sumo to and Wong, 1977), p o r o s i t y can be c a l c u l a t e d from: P o r o s i t y = water volume water vol.+ sediment v o l . where; Water volume = Weight of water/water den-s i t y and Sediment volume = Weight o f dry sediment/sediment g r a i n d e n s i t y . The r e s u l t s o f t h i s c a l c u l a t i o n are shown i n Table VI. There i s a d i s t i n c t change i n p o r o s i t y between samples 68-71. Sample 68 i s seen to have the h i g h e s t p oros-i t y (0.9598) i n t h i s s e c t i o n . Above t h i s l e v e l , p o r o s i t y de-cre a s e s to a value a t the co r e - t o p o f 0.930, a value which i s lower than the p o r o s i t y a t f i n a l compaction estimated by Matsumoto and Wong (1977). P o r o s i t y i s a l s o seen to decrease below sample 68. These data imply t h a t there has been a change i n sedimen t a t i o n w i t h i n F i n l a y s o n Arm and t h a t the sediment a t the top o f t h i s c o r e , above 15cm depth, i s d i s t i n c t from t h a t i n the lower p a r t . Support f o r t h i s o b s e r v a t i o n i s p r o -40 v i d e d by the data on major element geochemistry i n s e c t i o n 3.4. Using the formula o f Robbins and Edgington (1975), the sample depths must be c o r r e c t e d f o r compaction assuming s t e a d y - s t a t e sedimentation. Because o f the non-steady-state i m p l i e d by these data, the s e d i m e n t a t i o n r a t e cannot be estimated. V a r i a t i o n s i n the s e d i m e n t a t i o n r a t e might r e s u l t i n v a r i a t i o n of the f l u x o f a i o P b to the sediment s u r f a c e . Hence, observed decreases i n a i o P b a c t i v i t y cannot be d i r e c t l y used to d e r i v e a s e d i m e n t a t i o n r a t e from the h a l f -l i f e o f the i s o t o p e (22.2 y r s ) . T h i s , i n t u r n , means t h a t i t i s not p o s s i b l e to determine a chronology f o r core CPIV. In an attempt to v e r i f y the change i n se d i m e n t a t i o n w i t h i n the top 15cm o f the c o r e , the c a l c u l a t e d p o r o s i t y f o r the s u r f a c e was taken to be s u r f a c e p o r o s i t y and the p o r o s i t y a t f i n a l compaction was assumed to be 0.929, a value c l o s e to t h a t of Matsumoto and Hong (1977). T h i s avoids the problem o f the p o r o s i t y a t f i n a l compaction being g r e a t e r than the s u r f a c e p o r o s i t y . The r e s u l t s o f these c a l c u l a t i o n s are shown i n Fig.3.1.4. Although t h i s c a l c u l a t i o n i s somewhat q u e s t i o n a b l e , the r e s u l t s show t h a t there i s a d i s t i n c t change i n sedimentation a t around sample 70, with the upper s e c t i o n having a lower r a t e . Above sample 70 a r a t e o f 0.3cm/y i s c a l c u l a t e d while below t h a t sample the s e d i m e n t a t i o n r a t e i n c r e a s e s to 1.03cm/y. Carpenter and Beasley (1981) found 41 Fig:3.1.4 Correc ted depth (based on porosity ca lculated from chloride) against exceaa 210Pb Q _ 10 ro 3 2 _ KD ho CT 0. Sad iman la l lon R a l a s ' » gradient:0.01 0.31 cm/yr . 210Pb d . c a y constant =0.031 1 gradient :0.03 1.03 cm/yr I I I I I I I I I | I I I M I I I I | I I I I I I I I I | 0 10.0 20.0 30.0 Corrected Depth, ( cm) e r r a t i c a i o P b p r o f i l e s i n cores from F i n l a y s o n Arm and a t t r i b u t e d t h i s to e p i s o d i c or d i s c o n t i n u o u s sedimentation at t h a t s i t e . Another example o f d i s c o n t i n u o u s sedimentation has been r e p o r t e d by Smith and Walton (1980) i n the Saguenay f j o r d , Quebec. They observed l a y e r s o f sandy mud i n t e r c a l a t e d i n the normal f i n e - g r a i n e d sediments of the f j o r d with very low a*°Pb a c t i v i t i e s ; these sandy l a y e r s were i n t e r p r e t e d as t u r b i d i t e s c o n t a i n i n g a i o P b - d e p l e t e d t e r r e s t r i a l m a t e r i a l . They avoided the problems a s s o c i a t e d with non s t e a d y - s t a t e sedimentation by assuming t h a t these l a y e r s were d e p o s i t e d q u i c k l y and t h a t the a c t i v i t y p r o f i l e o f the i s o t o p e i n the f i n e - g r a i n e d sediments had not been d i s t u r b e d , so t h a t s e d i m e n t a t i o n r a t e s c o u l d s t i l l be estimated. In core CPIV, i t appears t h a t l a y e r s i n the bottom h a l f o f the s e c t i o n are t r u e varves and r e p r e s e n t seasonal d e p o s i t i o n (see s e c t i o n s 3 .4 and 3.5), while the top of the core c o n t a i n s sediments i n which the seasonal s i g n a l i s s e v e r e l y reduced. T h i s sediment does not, however, have the low a t o P b a c t i v i t i e s t h a t c h a r a c t e r i z e the r a p i d l y d e p o s i t e d t e r r e s t r i a l l a y e r s d e s c r i b e d by Smith and Walton (1980) and a i o P b a c t i v i t i e s appear to be c o n s i s t e n t with other s u r f a c e or n e a r - s u r f a c e v a l u e s found i n Saanich I n l e t . There i s a l s o some i n d i c a t i o n from the S i , Ba and diatom data t h a t there i s a change i n p r o d u c t i o n a s s o c i a t e d with t h i s change i n sedimentation. The geochemical data, e s p e c i a l l y Sr and V, and many o f the major elements, show l i g h t / d a r k v a r i a t i o n i n the p a r t of the core below sample 70 i n d i c a t i n g p u l s e s of l i t h o g e n o u s i n p u t to F i n l a y s o n Arm, which can o n l y be a t t r i b u t e d to seasonal v a r i a t i o n s i n r u n o f f . Notes taken d u r i n g the s c r a p i n g o f the samples show t h a t the laminae became i n d i s t i n c t and hard to f o l l o w around sample 70 and continued to be so up to the top o f the c o r e . I t i s d i f f i c u l t to r e c o n c i l e the p r e s e r v a t i o n of seasonal s i g n a l s i n the geochemical (see s e c t i o n 3.4 and 3.5) and the diatom data (see s e c t i o n 3.6), with the observed decrease i n a*°Pb a c t i v i t y . The decrease i n a c t i v i t y means t h a t there are approximately 3 h a l f - l i v e s (67 y r s ) w i t h i n the s e c t i o n s t u d i e d , while the varve counts i n d i c a t e o n l y 18 years o f d e p o s i t i o n . One e x p l a n a t i o n f o r t h i s i s t h a t l a r g e , n a t u r a l l y - i n d u c e d f l u c t u a t i o n s i n the s e d i m e n t a t i o n r a t e and thereby o f the f l u x o f a i o P b to the sediments, have o c c u r r e d . However, t h i s should have produced f l u c t u a t i o n s i n the p r o f i l e o f a i o P b a c t i v i t i e s ( F i g . 3 . 1 . 1 ) . These are not observed w i t h i n the sampling r e s o l u t i o n a v a i l a b l e . An a l t e r n a t i v e e x p l a n a t i o n o f the a i o P b data i s t h a t the d e p o s i t i o n o f the uppermost sediment, assuming t h a t i t i s o f t e r r e s t r i a l o r i g i n with low a i o P b a c t i v i t y (Smith and Walton ,1980), has d i l u t e d the n a t u r a l f l u x of a i o P b to the sediment. In t h i s case the decrease i n a i o P b i n t h i s s e c t i o n c o u l d not be assumed to be v i a r a d i o a c t i v e decay. 44 A t h i r d p o s s i b i l i t y i s t h a t the sediment type a t the top o f the core r e p r e s e n t s many years o f d e p o s i t i o n and th a t the l a y e r s sampled w i t h i n i t do not r e p r e s e n t annual d e p o s i t i o n . a i o P b i s seen i n F i g . 3.1.1 to have decreased from a s u r f a c e value o f 10 dpm/g to around 2 dpm/g. by sample 70. Th i s i n d i c a t e s t h a t the top l a y e r c o n t a i n s ap-proxi m a t e l y 45 years o f sediment i f a co n s t a n t s e d i m e n t a t i o n r a t e i s assumed and i f d i l u t i o n by t e r r e s t r i a l m a t e r i a l has not o c c u r r e d . Below sample 70 and down to the base o f the core , 2 1 ° P b i s not seen to reach background a c t i v i t y (1.0 dpm/g i n Saanich I n l e t , Br u l a n d , 1974); sample 50 has an excess a c t i v i t y o f around 1.0 dpm/g. Th i s i n d i c a t e s t h a t the bottom s e c t i o n o f the core spans a p e r i o d o f l e s s than one a i o P b h a l f - l i f e , approximately 15 yea r s , and t h i s i s i n agreement with the number o f varves sampled (sample 50-70, ten y e a r s ) . Large f l u c t u a t i o n s i n the f l u x o f a i o P b to the sediment s u r f a c e would r e q u i r e c o n s i d e r a t i o n o f any v a r i a t i o n o f **°Pb i n p u t to the I n l e t and must a l s o be co n s i d e r e d i n l i g h t o f the f a c t t h a t c o a s t a l waters are g e n e r a l l y thought o f as being p a r t i c l e - r i c h , which would pro v i d e a ready and cons t a n t source o f m a t e r i a l to t r a n s p o r t a i o P b to the sediments. I t i s proposed t h a t the top o f core CPIV c o n s i s t s o f a d i s t i n c t sediment type which was d e p o s i t e d d u r i n g a pe-r i o d o f decreased se d i m e n t a t i o n r a t e and a p e r i o d when t e r -r e s t r i a l m a t e r i a l may have d i l u t e d the a i o P b a c t i v i t y a s s o -4 5 e l a t e d with the f l u x o f marine d e t r i t u s to the sediments. T h i s sediment i s c h a r a c t e r i s e d by a decreased seasonal s i g -n a l o f p r o d u c t i o n , or o f a s i g n a l p r eserved on a s c a l e so f i n e t h a t i t c o u l d not be sampled d i s c r e t e l y . Below t h i s change i n sediment type, there i s a s e r i e s o f varves i n which a seasonal s i g n a l o f d e p o s i t i o n w i t h i n Saanich I n l e t i s p r eserved. I t w i l l be shown t h a t the a c t u a l p o i n t a t which the seasonal s i g n a l breaks down v a r i e s depending of the i n d i c a t o r c o n s i d e r e d . For example, major element s i g n a l s seem to show a change around sample 70 ( s e c t i o n 3.4), while V c o n c e n t r a t i o n s ( s e c t i o n 3.5) and the counts o f Chaetoceros ( s e c t i o n 3.6) appear to i n d i c a t e t h a t the change occurs i n c o n j u n c t i o n with the carbonate i n c r e a s e around sample 78 (see s e c t i o n 3.3). 3.2 Organic carbon and the c a r b o m n i t r o g e n r a t i o . S urface sediments i n F i n l a y s o n Arm have been shown to have the h i g h e s t content o f o r g a n i c carbon found i n the Saanich I n l e t . Values o f around 5% have been r e p o r t e d by Francois (1987) i n F i n l a y s o n Arm, while Gross and Gucluer (1964) r e p o r t r e d u c i n g c a p a c i t y , as e q u i v a l e n t grams o f c a r -bon, o f 7%. Organic carbon i s g e n e r a l l y seen to decrease with d i s t a n c e from the Goldstream R i v e r to around 3-4% i n the c e n t r a l b a s i n o f the I n l e t . However, t h i s d i s t r i b u t i o n i s not thought to r e p r e s e n t i n p u t from the Goldstream; r a t h e r , i t i s caused by lower s e d i m e n t a t i o n r a t e s a t the head of the I n l e t , meaning t h a t the carbon i s not d i l u t e d by 46 l i t h o g e n o u s i n p u t . Table VII p r e s e n t s a summary of the data o b t a i n e d from core CPIV. The o r g a n i c carbon p r o f i l e (Fig.3.2.1) shows s u r -face v a l u e s of around 5% d e c r e a s i n g to 3.2% a t around 25cm. and then i n c r e a s i n g a g a i n to v a l u e s s i m i l a r to those found a t the core top. T h i s i n c r e a s e i n carbon a t the top of the core might be e x p l a i n e d by the lower sedim e n t a t i o n proposed on the b a s i s of the 2 1 ° P b data. S i m i l a r l y , the i n c r e a s e a t the base o f the core might r e p r e s e n t a change i n sedimentation. There i s some geochemical evidence f o r t h i s (see s e c t i o n 3.4); however, i t i s not as w e l l d e f i n e d as the change observed i n the upper h a l f of the core. Below sample 70, the dark, laminae, with few e x c e p t i o n s , most n o t a b l y sample number 56, show higher c o n c e n t r a t i o n s o f o r g a n i c carbon than the l i g h t l a y e r s implying t h a t the g r e a t e s t input o f carbon c o i n c i d e s with winter d e p o s i t i o n . I t w i l l be shown t h a t t h i s i s a f a l s e i n t e r p r e t a t i o n and t h a t o r g a n i c carbon v a l u e s , w i t h i n the d i s t i n c t v a rves, are a c t u a l l y higher i n the l i g h t l a y e r s i f allowance i s made f o r d i l u t i o n by o p a l . The carbon to n i t r o g e n r a t i o of sedimentary o r -g a n i c m a t e r i a l has been used to i d e n t i f y the source of s e d i -mentary o r g a n i c carbon. Malcolm and Price (1984) observed C:N r a t i o s of around 17 i n p a r t i c u l a t e m a t e r i a l from r i v e r s and Stuermer et al (1978) showed a r a t i o of 13.5 f o r f o r e s t s o i l s . T h i s i s thought to be low f o r the r e g i o n around Saanich I n l e t , where a value of 17-18 might be more 47 T a b l e V I I C a r b o n , C a r b o n a t e , N i t r o g e n , C : N r a t i o a n d %Opa l R e s u l t s . S A M P L E %C1 % C t o t % C o r g % C ( C a C 0 3 ) %N C : N %OPAL DEPTH 86 11. 3 5. 41 4.79 0. 62 0. 50 9. 56 21. 2 0 85 11. 0 5. 86 5.03 0. 83 0. 53 9. 56 14. 7 3. 8 84 11. 1 5. 44 4.61 0. 83 0. 48 9. 50 13. 9 4. 2 83 11. 2 5. 17 4.53 0. 63 0. 43 10. 45 16. 4 6. 4 82 12. 3 5. 05 4. 33 0 . 72 0. 43 10. 14 17. 3 7. 5 81 12. 6 4. 94 4.42 0. 52 0. 50 8. 82 20. 0 7. 7 80 14. 2 5. 01 4.55 0. 47 0. 49 9. 26 23. 7 9. 5 79 13. 9 4. 82 4. 41 0. 41 0. 47 9. 44 24. 7 9. 8 78 15. 1 4. 46 4.18 0. 28 0. 42 9. 91 27. 3 10. 9 77 15. 1 4. 88 4.57 0. 31 0. 47 9. 70 26. 7 11. 3 76 15. 3 4. 59 4.29 0. 30 0. 47 9. 07 27. 4 11. 5 75 14. 5 4. 59 4. 25 0. 33 0. 45 9. 41 29. 7 11. 8 74 16. 7 4. 08 3.76 0. 32 0. 40 9. 49 30. 2 12. 7 73 16. 3 4. 52 4. 23 0. 29 0. 44 9. 58 29. 8 13. 3 72 16. 5 4. 32 4.04 0 . 28 0 . 41 9. 91 34. 5 14. 1 71 15. 4 3. 74 3.46 0. 28 0. 38 9. 00 34. 1 15. 4 70 17. 2 4. 22 3.97 0. 26 0. 43 9. 15 36. 9 16. 2 69 16. 4 3. 93 3.67 0. 27 0. 42 8. 63 36. 5 17. 1 68 20. 2 4. 14 3.86 0. 28 0. 43 9. 04 45. 2 18. 3 67 16. 2 4. 22 3.93 0. 29 0. 43 9. 06 32. 9 18. 7 66 18. 3 3. 67 3.44 0 . 22 0. 38 8. 95 33. 9 18. 9 65 14. 9 3. 98 3.67 0. 31 0. 41 9. 00 27. 2 19. 5 64 18. 8 3. 64 3. 36 0 . 29 0. 36 9. 22 39. 7 19. 7 63 16. 4 3. 79 3.55 0. 24 0. 38 9. 24 36. 1 19. 9 62 16. 5 3. 99 3.75 0. 23 0. 40 9. 33 31. 4 20. 6 61 14. 4 4. 01 3.76 0. 25 0. 40 9. 40 27. 3 21. 1 60 18. 0 3. 76 3.53 0. 22 0. 36 9. 82 43. 1 22. 4 59 17. 3 4. 28 3.92 0. 35 0. 41 9. 56 31. 4 22. 6 58 19. 0 4. 01 3.78 0. 23 0. 42 8. 96 46. 5 23. 2 57 13. 9 4. 40 4.12 0. 27 0. 47 8. 83 27. 5 24. 3 56 15. 6 5. 37 5.15 0. 22 0. 54 9. 48 35. 2 27. 2 55 12. 8 4. 49 4. 21 0. 27 0. 44 9. 66 21. 7 27. 7 54 14. 4 4. 23 3.97 0. 26 0. 44 9. 01 28. 5 28. 4 53 13. 1 4. 70 4.42 0. 28 0. 48 9. 30 21. 5 29. 7 52 15. 0 4. 25 4.04 0. 22 0. 43 9. 49 31. 4 30. 6 51 12. 4 5. 27 4.95 0. 33 0. 55 9. 07 20. 3 31. 6 50 15. 4 4. 44 4.23 0. 21 0. 47 8. 94 27. 9 32. 2 * A L L V A L U E S ARE S A L T C O R R E C T E * C o r g . = C ( t o t ) - C ( C a C 0 3 ) Fig: 3.2.1 % ORGANIC CARBON 48 X OROAMC CARBON Fig: 3.2.2 C A R B O N : NITROGEN RATIO RSD 2<T I 1 CARBON:NrrRO0EN RATIO 49 a p p r o p r i a t e (Dr.Love, S o i l Science,UBC. pers.comm). Redfield et al (1963) showed a C:N r a t i o f o r marine plankton o f around 6. Sholkovitz (1973) d i s c u s s e d the C:N r a t i o i n anoxic sediments from the Santa Barbara b a s i n and p o i n t e d out t h a t the l o s s of l a b i l e n i t r o g e n d u r i n g sedimentation w i l l i n c r e a s e the C:N r a t i o of marine o r g a n i c matter r e a c h i n g the s e a f l o o r . The p l o t of the C:N r a t i o i n core CPIV ( F i g . 3.2.2) r e v e a l s a mean value o f around 9.4, which i n d i c a t e s t h a t the major source o f carbon i s marine. I t a l s o shows t h a t most o f the d i f f e r e n c e s between samples are not s i g n i f i c a n t when the 2a e r r o r i s c o n s i d e r e d ; the s i z e o f the e r r o r i s due to the r e l a t i v e l y poor p r e c i s i o n of the n i t r o g e n a n a l y s i s (±2.1%). The p r o f i l e o f o r g a n i c carbon i s approximately m i r r o r e d by t h a t o f the S i : A l r a t i o ( F i g . 3 . 2 . 3 ) , which i s c o n t r o l l e d by the r e l a t i o n s h i p between s i l i c o n d e r i v e d from diatom o p a l , a l u m i n o s i l i c a t e s and q u a r t z , and aluminium c o n t a i n e d i n a l u m i n o s i l i c a t e s . The r a t i o i s low a t the top and bottom o f the p r o f i l e and i n c r e a s e s i n the c e n t r a l p a r t of the s e c t i o n where the o r g a n i c carbon content i s low. I t w i l l be shown i n the s e c t i o n on the major elements t h a t the decrease i n the S i : A l r a t i o a t the top o f the core might be caused by a change i n mineralogy; however, the higher S i : A l r a t i o i n the c e n t r e of the core must e i t h e r r e f l e c t an i n c r e a s e i n the amount o f s i l i c a r e a c h i n g the sediments or a decrease i n the amount o f aluminium. Major and minor element data (see next s e c t i o n s ) do not p r o v i d e evidence f o r a 50 concomitant decrease i n the input of c l a y minerals nor an i n c r e a s e i n the amount o f quartz i n t h i s p a r t o f the c o r e ; thus the i n c r e a s e d S i : A l r a t i o , which i s always higher i n the l i g h t l a y e r s , must be accounted f o r by an i n c r e a s e i n the i n p u t of o p a l . I t f o l l o w s t h a t low o r g a n i c carbon values can be accounted f o r by d i l u t i o n . An estimate of the opal content o f the sediments can be d e r i v e d u s i n g the f o l l o w i n g formula; % o p a l = [ % S i . M P i . - ( % A l M n P f x S i : A l n « r . ) ] x2.14 (4) Where: Si:Aln« H = 3.5 which i s an i n t e r m e d i a t e value between 3.1, the S i : A l r a t i o f o r the Saanich g r a n o d i o r i t e (Clapp, 1913) and 3.9, the S i : A l r a t i o found i n winter d e p o s i t i o n caught i n sediment t r a p s deployed i n Saanich I n l e t (Francois, 1987)..2.14 = the atomic weight r a t i o o f o p a l , ( S i 0 2 ) , t o S i . Opal i s taken as S i 0 2 s i n c e the q u a n t i t y o f water a s s o c i a t e d with opal ( S i 0 2 . n H 20) i s p o o r l y d e f i n e d and the e r r o r a s s o c i a t e d with the assumption s of t h i s c a l c u l a t i o n w i l l mask the e r r o r a s s o c i a t e d with t h i s d e f i n i t i o n . The d i s t r i b u t i o n o f opal c a l c u l a t e d i n t h i s manner i s shown i n F i g . 3.2.4. Values range from 14% i n the top o f the core to around 45% i n some l i g h t l a y e r s lower i n the s e c t i o n . In a l l l a y e r s below sample 70 there are higher opal c o n t e n t s i n the l i g h t l a y e r s and t h i s i s to be expected i f these l a y e r s are annual varves. The decrease i n o r g a n i c carbon i n the c e n t r a l s e c -t i o n o f the core ( F i g . 3.2.1) i s matched by an i n c r e a s e i n the o p a l content of the sediments and t h i s i m p l i e s t h a t the carbon decrease i s caused by the d i l u t i o n o f sedimentary carbon by i n c r e a s e d i n p u t s of o p a l . The p r o f i l e of o r g a n i c F i g : 3 .2 .3 SILICON:ALUMINIUM RATIO. X Opal carbon can be c o r r e c t e d f o r t h i s d i l u t i o n by c a l c u l a t i n g %C on an o p a l - f r e e b a s i s u s i n g ; %Cop-X 1 - r — = % C a M » l « x 100 (5) 100-%opal A p r o f i l e o f o p a l - f r e e carbon i s presented i n Fig.3.2.5 and the r e l a t i v e l y low v a l u e s i n the c e n t r a l s e c t i o n are indeed removed. The p l o t of o p a l - f r e e carbon can be taken as a rough estimate of carbon f l u x i n t o the sediments thereby i n -d i c a t i n g r e l a t i v e d i f f e r e n c e s i n primary p r o d u c t i o n on the assumption t h a t the main i n p u t o f carbon i s d e r i v e d from t h i s source. Hence, the v a r i a t i o n between l a y e r s i n t h i s p r o f i l e may p r o v i d e an i n s i g h t i n t o p a s t p r o d u c t i o n i n t h i s p a r t of the I n l e t . However, on the b a s i s o f the evidence presented so f a r , the i n t e r p r e t a t i o n o f t h i s p r o f i l e i s not s t r a i g h t f o r w a r d . A comparison between the diatom v a l v e counts (Fig.3.2.6) and the o p a l - f r e e carbon p r o f i l e (Fig.3.2.5) r e v e a l s some s i m i l a r i t i e s but a l s o c o n t a i n s some major d i s c r e p a n c i e s . The most n o t i c e a b l e d i f f e r e n c e i s the high c e l l counts i n sample 64 which has a low o r g a n i c carbon content. T h i s sample does have a h i g h o p a l content (see F i g . 3 . 2 . 4 ) , and i t w i l l be shown i n s e c t i o n 3.6 t h a t i t a l s o c o n t a i n s r e l a t i v e l y h i g h counts of both Skeletonema costatum and Chaetoceros S D D . . both o f which are g e n e r a l l y small c e l l s and might e a s i l y l o s e t h e i r carbon d u r i n g sedimentation. SAMPLE NUMBER. SAMPLE NUMBER 5 4 One p o s s i b l e e x p l a n a t i o n f o r the d i f f e r e n c e between these p r o f i l e s i s a v a r i a t i o n i n the amount of g r a z i n g to which a diatom bloom i s exposed. Heavy g r a z i n g w i l l d e s t r o y the c e l l s and r e l e a s e t h e i r contents while l e s s g r a z i n g might be expected to generate sediments with a higher carbon content. V a r i a t i o n i n p r e d a t i o n on the g r a z e r s might a l s o be a s i g n i f i c a n t f a c t o r i n determining the amount of carbon sedimented. The carbon content o f diatom c e l l s , as shown by the S i : C r a t i o , w i l l depend on a wide range o f v a r i a b l e s (see Spencer (1983) f o r a revi e w ) . Brzezinski (1985) d i s -cusses the v a r i a t i o n i n t h i s r a t i o w i t h i n c u l t u r e s o f a num-ber o f common diatom s p e c i e s s u b j e c t e d to d i f f e r e n t l i g h t and photoperiod c o n d i t i o n s . He a l s o c i t e s work where temperature and n u t r i e n t l i m i t a t i o n have a l s o been shown to change s i g n i f i c a n t l y the S i : C r a t i o . V a r i a t i o n s seen i n con-t r o l l e d l a b o r a t o r y c u l t u r e s are even more l i k e l y i n a n a t u -r a l system such as Saanich I n l e t . Changes i n the c l i m a t i c p a t t e r n s and oceanographic c o n d i t i o n s a f f e c t i n g the I n l e t w i l l i n t u r n a f f e c t the plan k t o n dynamics, n u t r i e n t c y c l e s and s p e c i e s s u c c e s s i o n , which w i l l , i n t u r n , a f f e c t the S i : C r a t i o i n l i v i n g c e l l s . In a d d i t i o n , d i s s o l u t i o n o f the s i l i c a f r u s t u l e s , g r a z i n g by zooplankton and b a c t e r i a l o x i -d a t i o n w i l l a f f e c t the r a t i o o f biogenous s i l i c a to carbon i n s e t t l i n g p a r t i c u l a t e s and t h e r e f o r e i n the remains t h a t become preserved i n the sediments. F i n a l l y , the n a t u r a l system and a l l i t s component v a r i a b l e s w i l l a l s o show 55 i n t e r a n n u a l , seasonal and even weekly v a r i a t i o n s . These c o n s i d e r a t i o n s are thought to account f o r the seemingly poor r e l a t i o n s h i p between opal and o r g a n i c carbon. In a d d i t i o n to the v a r i a t i o n s which occur t h a t d i -r e c t l y a f f e c t the diatom p o p u l a t i o n and the carbon they r e p -r e s e n t , there are a l s o i n d i r e c t e f f e c t s and other sources of o r g a n i c carbon. P h o t o s y n t h e t i c f l a g e l l a t e s such as d i n o -phytes, c r y p t o p h y t e s , c h l o r o p h y t e s and p r a s i n o p h y t e s , form an important p a r t o f the phytoplankton w i t h i n the S t r a i t of Georgia system and have been shown to be p a r t i c u l a r l y important i n the i n l e t s (Takahashi et al.,1977,1978; Harri-son et al., 1983). Nanno and p i c o p l a n k t o n are a l s o b e g i n n i n g to be c o n s i d e r e d as important components o f the p l a n k t o n i c f l o r a . I t i s not l i k e l y t h a t these s o f t - w a l l e d algae would c o n t r i b u t e s i g n i f i c a n t amounts of carbon to the sediments s i n c e t h e i r c e l l w a l l s would probably be q u i c k l y broken down and the carbon r e l e a s e d to the seawater; however, v a r i a t i o n s i n the s i z e o f t h e i r p o p u l a t i o n s might have a s i g n i f i c a n t e f f e c t on t h a t o f the diatoms by way of c o m p e t i t i o n f o r nu-t r i e n t s . Only d i n o f l a g e l l a t e s produce any remains which might become preserved i n the sediments, although s t u d i e s o f raw sediments as smear s l i d e s showed no evidence of t h e i r c y s t s i n t h i s c o re. The laminae below sample 70 are thought to have a higher s e d i m e n t a t i o n r a t e and t h i s s e c t i o n o f the core c o n t a i n s a r e c o r d o f annual p r o d u c t i o n as varves. Based on these assumptions, the p r o f i l e of o p a l - f r e e o r g a n i c carbon 56 r e v e a l s t h a t v a r i a t i o n between the carbon content o f the l i g h t (summer) and dark (winter) l a y e r s i s preserved i n the sediments. Between samples 52-62 and from 67-72 the l i g h t l a y e r s have c o n s i s t a n t l y higher carbon contents i m p l y i n g t h a t the major carbon source i s the summer p r o d u c t i o n i n s u r f a c e waters. 3.3 Carbonate. The carbonate p r o f i l e o f core CPIV shown i n Fig.3.3.1 i s c h a r a c t e r i s e d by a d i s t i n c t peak a t the top of the c o r e . The data are presented i n Table VII (see s e c t i o n 3.2). P l a n k t o n i c organisms which produce t e s t s o f c a l c i u m carbonate ( c a l c i t e and a r a g o n i t e ) are not thought to be major components of the pl a n k t o n i n the S t r a i t o f Georgia system s i n c e no r e f e r e n c e can be found to them i n the papers by Takahashi et al (1978), Hobson (1980) and Harrison et al. (1983). The steep bathymetry o f the I n l e t , e s p e c i a l l y around the s i t e from which t h i s core was c o l l e c t e d , g r e a t l y r e s t r i c t s areas o f mud f l a t s i n which b e n t h i c b i v a l v e s , such as clams, t h r i v e , and i t i s t h e r e f o r e a reasonable assumption t h a t the input o f carbonate d e r i v e d from b i o g e n i c sources i s s m a l l . Past s t u d i e s o f the sediments w i t h i n the I n l e t have shown t h a t the h i g h e s t c o n c e n t r a t i o n o f carbonate i s found c l o s e l y a s s o c i a t e d with the cement p r o d u c t i o n f a c i l i t y a t Bamberton (see Fig.3.3.2) (Gross and Gucluer, 1964; Francois, 1987). T h i s f a c t o r y produced cement u s i n g a l o c a l 57 Fig: 3.3.1 CARBONATE PROFILE. 1 3 6 7 X CARBONATE Fig: 3.3.2 Distribution of carbonate in surface sediments of Saanich Inlet, (after Francois,1987) limestone d e p o s i t from 1912 to 1980 ( T i l b u r y Cement, Cobble H i l l , pers comm.). The i n p u t of carbonate to the i n l e t from t h i s f a c i l i t y has been shown to c o n t a i n high c o n c e n t r a t i o n s of z i n c and l e a d (Francois, 1987). These are probably p o l l u t a n t s d e r i v e d from p r o d u c t i o n processes. A comparison between the carbonate p r o f i l e ( F i g . 3.3.1) and t h a t of Zn ( F i g . 3.5.14) and o f Pb ( F i g . 3.5.16) shows t h a t there are indeed i n c r e a s e d c o n c e n t r a t i o n s o f both these elements c o i n c i d e n t with the r i s e i n carbonate v a l u e s , although the match i s c l o s e r between Pb and carbonate. Calcium ( F i g . 3.4.14), i s a l s o seen to i n c r e a s e i n a s s o c i a t i o n with the carbonate p r o f i l e . F u r t h e r d i s c u s s i o n of these element p r o f i l e s i s g i v e n i n s e c t i o n s 3.4 and 3.5. F i g u r e 3.3.2 shows t h a t there i s a t r a n s p o r t of carbonate from the p o i n t source a t Bamberton towards F i n l a y s o n Arm, and i t i s probable t h a t the carbonate and c a l c i u m p r o f i l e s are r e f l e c t i n g the i n f l u e n c e o f input from cement p r o d u c t i o n . F i n i s h e d P o r t l a n d cement i s composed o f c a l c i u m aluminates and c a l c i u m s i l i c a t e s . Four major mineral phases are p r e s e n t : C a 3 S i O B , Ca 2SiCU, CaaAl^Os and C a * ( A l , F e ) 0 B (Regourd, 1979). The p r o p o r t i o n o f these depends upon the i n i t i a l raw mix, but a cement g e n e r a l l y c o n t a i n s 60-65% CaO, 22-24% SiOa, 4-7% A1*0», 2-4% F e a O a and MgO, NaO and K*0 t o -gether t o t a l l i n g around 2-4% by weight (Glasser, 1979). A raw mix o f limestone, c l a y and a number of a c -c e s s o r y m i n e r a l s , which p r o v i d e the r e q u i r e d amounts of Fe and A l , i s homogenised and burnt i n a k i l n a t around 1200<>C GO to d r i v e water out of the c l a y s and reduce the carbonate to lime. T h i s produces ''clinker' which i s subsequently ground to f i n i s h e d cement. Burning o f the raw mix r e s u l t s i n the p r o d u c t i o n of v o l a t i l e gases and waste dust t h a t has a high a l k a l i content (Hawkins, 1979). Some dust i s r e t u r n e d to the k i l n but most i s removed i n order to c o n t r o l the a l k a l i con-t e n t of the f i n a l * c l i n k e r ' . Since e x t r a c t e d dust g e n e r a l l y comes from e a r l y i n the k i l n process when the r e d u c t i o n o f carbonate to lime has not y e t o c c u r r e d , the dust c o n t a i n s a l o t o f CaCOa (Dr. S Mindess. Dept. C i v i l Eng. U.B.C. pers comm). Estimates o f s e d i m e n t a t i o n r a t e d e r i v e d from the a i o P b data, although somewhat u n c e r t a i n , imply t h a t the sediments a t the top of the core (down to sample 70) were d e p o s i t e d over a p e r i o d o f about 45 y e a r s . However, the a c t i v i t y o f a i o P b i s s t i l l h i g h a t the top of the core (10 dpm/g) and i t i s c o n s i d e r e d a reasonable assumption t h a t the i n c r e a s e i n carbonate does not correspond to the s t a r t o f p r o d u c t i o n i n 1912. S t u d i e s u s i n g a l k a l i n i t y models i n the a n o x i c Santa Barbara b a s i n o f f southern C a l i f o r n i a have shown t h a t carbonate w i l l c e r t a i n l y be p r e s e r v e d and may even be a u t h i -g e n i c a l l y produced under the d i a g e n e t i c c o n d i t i o n s p r e v a i l -i n g i n such sediments (Sholkovitz 1973). However, the amount of carbonate a t the c o r e - t o p , on the order of a 4% i n c r e a s e , i s too l a r g e to be accounted f o r by a u t h i g e n i c p r o d u c t i o n , nor does i t seem l i k e l y t h a t a change i n carbonate 61 p r e s e r v a t i o n has o c c u r r e d . Personnel a t T i l b u r y Cement, Cobble H i l l s t a t e t h a t between 1960 and 1963, i n e f f i c i e n t e x t r a c t i o n o f the k i l n dust a t the p l a n t r e s u l t e d i n the p r o d u c t i o n o f a l o t of limestone dust which c o u l d not be used f o r the p r o d u c t i o n o f cement, and t h a t t h i s was disp o s e d o f by dumping i t i n t o a d i s u s e d quarry p i t . T h i s p r a c t i c e was h a l t e d i n 1963 because r u n o f f from the dust dump was found to be e n t e r i n g the I n l e t v i a H o l l i n s Creek, running a d j a c e n t to the p l a n t , and the lime content o f water drawn from t h a t creek by l o c a l c o t t a g e s was very h i g h . The i n c r e a s e i n carbonate seen i n t h i s core ( F i g . 3.3.1) may be a t t r i b u t e d to t h i s dump and can thereby be used as a time marker r e p r e s e n t i n g the p e r i o d 1960-63. Three e x p l a n a t i o n s are p o s s i b l e f o r the di s c r e p e n c y between the 2*°Pb-derived time i n t e r v a l f o r the upper s e c t i o n o f the core (» 45yrs) and the date o f around 1960 a t the base of the carbonate peak. F i r s t l y , the carbonate peak does not r e p r e s e n t the dust-dump but r a t h e r i s the r e c o r d o f i n c r e a s e d p r o d u c t i o n a t Bamberton and thus r e p r e s e n t s a longer p e r i o d o f d e p o s i t i o n . Secondly, the peak does r e p r e s e n t the dust-dump and some mixing has o c c u r r e d i n the top-most sediments. T h i r d l y , the carbonate peak i s preserved w i t h i n a changed sedim e n t a t i o n regime c h a r a c t e r i s e d by a slower sedimentation r a t e and t h a t t h i s , together with d i l u t i o n e f f e c t s o f a changed mineralogy, accounts f o r the observed a*°Pb a c t i v i t y . These p o s s i b i l i t i e s are a l l supported by the a v a i l a b l e i a 7 C s data (Table I I I , S e c t i o n 3.1) which show t h a t there i s more 1 3 - 7Cs i n the c o r e - t o p ; there i s no c l e a r d e f i n i t i o n o f the 1963 f a l l o u t peak. I f the carbonate peak r e p r e s e n t s the 1960-63 dust-dump then the 1 3 r C s can be used to support t h i s . Sample 83, thought to be 1968 sedimentation on the b a s i s o f a i o P b , has a higher 1 3 T C s c o n c e n t r a t i o n (190±50 dpm/kg) than sample 80 (150±50 dpm/kg). Since sample 85 i s the observed maximum of carbonate (between 1960-63) then i t should have higher v a l u e s of * a r C s . I t might a l s o be expected t h a t the decreased carbonate c o n c e n t r a t i o n i n sample 86 would show decreased * 3 7Cs a c t i v i t y s i n c e atmospheric * 3 7Cs f a l l o u t i s known to decrease s h a r p l y a f t e r 1963 (Robbins and Edgington, 1975). R a d i o a c t i v e caesium i s measurable as atmospheric f a l l o u t from 1945 u n t i l the p r e s e n t although there i s a c l e a r decrease a s s o c i a t e d with the c e s s a t i o n o f atmospheric t e s t i n g i n 1963, and thus the two p o i n t s measured might be anywhere w i t h i n t h a t time. However, the v a l u e s i n t h i s core (CPIV) are h i g h , although not as high as those («400 dpm/kg) r e p o r t e d by Carpenter and Beasley (1981) i n F i n l a y s o n Arm. They are thought to be higher than post-1963 background; a value f o r t h i s o f around 50 dpm/kg i s r e p o r t e d by Robbins and Edgington (1975) i n Lake Michigan. Measurement o f more samples f o r '""'Cs would be r e q u i r e d to d e f i n e c l e a r l y the 1963 peak. The f a c t t h a t d i s t i n c t i o n s between samples w i t h i n t h i s s e c t i o n are preserved (see major element data on sample 75 f o r example) supports the idea t h a t l i t t l e mixing of the upper sediments has o c c u r r e d d u r i n g c o r i n g . I t i s concluded t h a t the * a rCs data supports the c o r r e l a t i o n o f the carbonate peak with the dust-dump. T h i s i m p l i e s t h a t some 20 years of sediments have been l o s t d u r i n g c o r i n g , presumably because o f the f l u i d nature o f the u n c o n s o l i d a t e d Saanich sediments. 3.4 Bulk mineralogy and the maior elements. The r e s u l t s presented i n the p r e v i o u s two s e c t i o n s have shown t h a t there i s a s i g n i f i c a n t d i l u t i o n o f the l i t h o g e n o u s components of these sediments by biogenous o p a l . For t h i s reason, the element p r o f i l e s r e p o r t e d here are shown as u n c o r r e c t e d p r o f i l e s and, with the e x c e p t i o n of S i and the S i : A l r a t i o , are presented on an o p a l - f r e e b a s i s (see s e c t i o n 3.2). D i s t i n c t i o n between S i i n biogenous opal and l i t h o g e n o u s S i would r e q u i r e the chemical d e t e r m i n a t i o n of o p a l r a t h e r than a c a l c u l a t i o n based on an assumed S i : A l r a t i o o f pure l i t h o g e n o u s i n p u t . 3.4.1 Mineralogy. A n a l y s i s of u n t r e a t e d bulk samples by X-ray d i f f r a c t i o n showed t h a t , i n g e n e r a l , there was l i t t l e miner-a l o g i c a l d i f f e r e n c e between the samples. Examples of the s p e c t r a o b t a i n e d are presented i n F i g . 3.4.1. Some v a r i a t i o n i n the h e i g h t o f the peaks was observed, but no sample c o u l d 64 Fig:3.4.1 Examples of XRDspectra Quartz 3.3A Feldspars SAMPLE 85 be d i s t i n g u i s h e d as having a c l e a r l y d i f f e r e n t bulk m i n e r a l -ogy. The main XRD peaks seen i n these samples were qu a r t z , f e l d s p a r , c h l o r i t e and o c c a s i o n a l l y minor i l l i t e . The small amounts o f i l l i t e i n these samples i s c o n t r a r y to the a s s e r t i o n s of Gross and Gucluer( 1964) and Carpenter and Beasley (1981) t h a t the main source of sediments to the c e n t r a l b a s i n o f the I n l e t i s the F r a s e r R i v e r plume. While t h i s may be the case i n the main p a r t o f the I n l e t and c l o s e r to the s i l l (Francois, 1987), i t does not appear to be the case i n F i n l a y s o n Arm. P r o f i l e s o f the q u a r t z : f e l d s p a r r a t i o , i n d i c a t i n g changes i n the bulk composition of the l i t h o g e n o u s i n p u t to the I n l e t , and o f the q u a r t z : c h l o r i t e r a t i o , i n d i c a t i n g a comparison between coarse and f i n e - g r a i n e d i n p u t , are shown i n F i g . 3.4.2 and F i g . 3.4.3. These data were d e r i v e d from a comparison o f the XRD peak h e i g h t s and are s e m i - q u a n t i t a t i v e . The q u a r t z : c h l o r i t e r a t i o i s h i g h l y v a r i a b l e ; sam-p l e s 75 and 62 are seen to have p a r t i c u l a r l y h i g h r a t i o s im-p l y i n g t h a t these samples are c o a r s e r - g r a i n e d l a y e r s . There does not appear to be any d i s t i n c t i o n between the upper and lower sediment types on the b a s i s of t h i s r a t i o . However, there does seem to be h i g h e r r a t i o s i n the l i g h t l a y e r s , which, i f i t means r e l a t i v e l y more q u a r t z , i m p l i e s a summer inp u t o f l i t h o g e n o u s m a t e r i a l ; t h i s would not be c o n s i s t e n t with a p u l s e d i n p u t o f t h i s m a t e r i a l as a r e s u l t o f winter r u n o f f . I t i s thought u n l i k e l y t h a t the summer c o n t r i b u t i o n 66 Fig: 3.4.2 QUARTZ:CHLORITE RATIO PEAK HEIGHTS FROM XRO DATA QUARTZ: CHLORFTE F±£1_3A^ QUARTZ:FELDSPAR RATIO PEAK HEIGHTS FROM XRO DATA QUARTZ: FELDSPAR 67 o f the F r a s e r R i v e r plume to the sediments o f Saanich I n l e t would c o n t a i n much quartz a f t e r i t s passage across the S t r a i t o f Georgia. On the other hand, the high r a t i o s might i n d i c a t e p r o p o r t i o n a t e l y lower c h l o r i t e and t h i s would be i n keeping with a seasonal d e p o s i t i o n , i m p l y i n g a pulsed input o f t h i s m i n e r a l . T h i s i n t e r p r e t a t i o n does, however, r e q u i r e a steady i n p u t of q u a r t z . One other notable f e a t u r e of t h i s p r o f i l e i s the lower r a t i o s between samples 70-75 as compared with the g e n e r a l l y higher r a t i o s i n the c e n t r a l s e c t i o n of the core. T h i s i s approximately c o i n c i d e n t with the proposed change i n sediment type but i s not seen to continue to the c o r e - t o p . F i g . 3.4.3 shows the q u a r t z : f e l d s p a r r a t i o and t h i s too shows some s i g n i f i c a n t v a r i a t i o n s . Samples 50,59 and 86 are seen to have hi g h r a t i o s which must i n d i c a t e , s i n c e they show no d i s t i n c t i o n i n the q u a r t z : c h l o r i t e r a t i o , t h a t these samples c o n t a i n l e s s f e l d s p a r . There appear to be l i t t l e c o n s i s t e n t d i f f e r e n c e s between the l i g h t and dark l a y e r s . At the top o f the core the dark l a y e r s appear to have higher r a t i o s , but a t the base of the c o r e , between samples 50-56, t h i s t r e n d i s r e v e r s e d . Samples 70-75, seen to have low q u a r t z t c h l o r i t e r a t i o s , are d i s t i n g u i s h e d here by being q u i t e homogeneous, while samples 64-68 are c h a r a c -t e r i s e d by low q u a r t z : f e l d s p a r r a t i o s . 6B 3.4.2 Major elements. The major element c o n c e n t r a t i o n s are presented i n Table V I I I . I t w i l l be shown i n t h i s s e c t i o n t h a t i n the middle s e c t i o n o f t h i s c o r e , between samples 55-70, many of the major elements appear to i n d i c a t e a seasonal input o f li t h o g e n o u s m a t e r i a l to the sediments. T h i s lends support to i n t e r p r e t a t i o n o f the laminae as varves. I t w i l l a l s o be shown t h a t there appears to be a change i n sediment type above sample 70-75. T h i s i s i n d i c a t e d by s e v e r a l elements and element r a t i o s (Ti,Fe,and S i f o r example), although there appears to be no evidence o f a change i n bulk mineralogy (see F i g . 3 . 4.1). I t can onl y be assumed t h a t the core top sediment c o n t a i n s amorphous or p o o r l y - c r y s t a l l i n e m i neral phases which cannot be de t e c t e d by XRD. I t has been suggested i n s e c t i o n 3.1 t h a t t h i s change i n mineralogy was probably accompanied by a change i n sedimentation r a t e , meaning t h a t s e d i m e n t a t i o n i n the top of the core cannot be assumed to be s t e a d y - s t a t e . However, the presence o f d i s t i n c t varves i n the bottom h a l f o f the core i m p l i e s t h a t s e d i m e n t a t i o n w i t h i n t h i s s e c t i o n may have been steady s t a t e . S i l i c o n ( F i g . 3 . 4 . 4 ) and A l ( F i g . 3 . 4 . 6 ) are both s t r o n g l y a s s o c i a t e d with d e t r i t a l i n p u t ; S i i s present i n qu a r t z , f e l d s p a r and c l a y m i n e r a l s and A l i s a s s o c i a t e d with f e l d s p a r and c l a y s . The S i : A l r a t i o i s presented i n F i g . 3 .4.5. In Saanich I n l e t sediments, i t has been shown t h a t Table VII I Concent ra t ions o f Major Elements. % by Height SAMPLE %Si %A1 %Fe %Ca %Mg %K %p %Ti Sanox Sox 86 26. 40 4. 71 3. 37 2. 54 1. 94 0 .82 0. 115 0. 28 866 679 85 25. 35 5. 28 3. 80 3. 18 1. 99 0 .89 0. 131 0. 31 531 347 84 24. 18 5. 05 3. 59 3. 11 1. 98- 0 .83 0. 126 0. 29 701 518 83 25. 23 5. 02 3. 45 2. 73 2. 02 0 .92 0. 115 0. 29 523 337 82 25. 81 5. 07 3. 41 2. 84 2. 11 0 .88 0. 118 0. 29 649 445 81 24. 91 4. 45 3. 03 2. 23 1. 94 0 .83 0. 108 0. 27 727 517 80 26. 88 4. 51 3. 03 2. 31 2. 13 0 .77 0. 106 0. 27 658 422 79 27. 44 4. 54 2. 90 1. 79 2. 09 0 .73 0. 105 0. 27 552 321 78 28. 43 4. 48 2. 89 1. 31 2. 22 0 .68 0. 090 0. 27 502 251 77 28. 28 4. 51 2. 90 1. 45 2. 25 0 .68 0. 108 0. 27 551 301 76 28. 29 4. 42 2. 93 1. 40 2. 35 0 .65 0. 097 0. 27 455 200 75 30. 85 4. 85 3. 23 1. 76 2. 50 0 .63 0. 112 0. 28 766 525 74 28. 62 4. 14 2. 59 1. 19 2. 42 0 .74 0. 094 0. 22 701 424 73 28. 81 4. 25 2. 67 1. 38 2. 26 0 .81 0. 105 0. 23 579 310 72 29. 57 3. 84 2. 27 1. 13 2. 20 0 .69 0. 087 0. 21 400 126 71 29. 85 3. 98 2. 39 0. 98 2. 16 0 .68 0. 085 0. 21 439 184 70 30. 52 3. 79 2. 40 0. 98 2. 45 0 .64 0. 095 0. 21 536 250 69 30. 68 3. 89 2. 49 1. 03 2. 47 0 .69 0. 112 0. 21 581 309 68 33. 97 3. 68 2. 31 0. 92 2. 87 0 .61 0. 097 0. 17 589 253 67 30. 89 4. 44 2. 66 1. 06 2. 37 0 .77 0. 099 0. 22 460 190 66 32. 56 4. 78 2. 96 1. 09 2. 52 0 .77 0. 105 0. 18 533 230 65 29. 79 4. 88 2. 88 1. 22 2. 38 0 .71 0. 090 0. 27 505 258 64 30. 77 3. 50 2. 14 0. 95 2. 45 0 .55 0. 093 0. 18 474 162 63 30. 66 3. 95 2. 49 0. 98 2. 23 0 .67 0. 093 0. 22 616 344 62 27. 18 3. 57 2. 02 0. 74 1. 90 0 .52 0. 081 0. 09 481 206 61 29. 97 4. 91 3. 13 1. 19 2. 18 0 .83 0. 094 0. 29 574 336 60 31. 93 3. 38 2. 09 0. 75 2. 40 0 .55 0. 084 0. 18 487 189 59 31. 95 4. 93 2. 87 1. 28 2. 53 0 .82 0. 108 0. 27 514 227 58 33. 29 3. 31 1. 92 0. 76 2. 61 0 .55 0. 120 0. 17 452 137 57 29. 94 4. 88 3. 21 1. 32 2. 35 0 .76 0. 105 0. 27 584 353 56 28. 37 3. 40 2. 18 0. 82 2. 20 0 .63 0. 091 0. 20 542 283 55 27. 49 4. 96 3. 36 2. 88 2. 15 0 .84 0. 102 0. 27 594 382 54 29. 17 4. 53 3. 08 1. 11 2. 14 0 .82 0. 095 0. 26 591 352 53 28. 05 5. 14 3. 43 1. 37 2. 15 0 .88 0. 109 0. 30 552 334 52 29. 73 4. 30 2. 84 1. 08 2. 15 0 .80 0. 096 0. 24 462 213 51 28. 31 5. 38 3. 50 1. 58 2. 13 0 .95 0. 118 0. 29 760 554 50 30. 27 4. 93 3. 61 1. 17 2. 25 0 .86 0. 115 0. 22 456 200 * A l l va lues are s a l t - c o r r e c t e d . * Sulphur va lues are i n ppm. Sanox assumes t o t a l S04 r e d u c t i o n . Sox i n c l u d e s the second c o r r e c t i o n r e q u i r e d fo r o x i c seawater. Sample sulphur va lues are between these two v a l u e s . 70 Fig: 3 .4.5 S I L I C O N ' . A L U M I N I U M R A T I O . SKAI 71 opal i s an important component, and below sample 70 both S i and the S i : A l r a t i o are higher i n the l i g h t l a y e r s which i s c o n s i s t e n t with a summer input of o p a l . Clapp (1913) r e p o r t s S i and A l values of the Saanich g r a n o d i o r i t e with a r a t i o of 3.1 and of the Wark g n i e s s , p a r t of the J u r a s s i c metamorphic complex o u t c r o p p i n g along S q u a l l y Reach, of 2.4. The s i g n i f i c a n t l y higher average r a t i o i n the Saanich I n l e t sediments ( F i g . 3.4.5) i n d i c a t e s the c o n t r i b u t i o n of opal to these sediments. An i n t e r e s t i n g f e a t u r e o f t h i s r a t i o i s the s i g n i f i c a n t decrease above sample 70. The f a l l i s caused by d e c r e a s i n g S i content of the sediment which might r e f l e c t a decrease i n p r o d u c t i o n or a change i n the mineralogy of the d e t r i t a l l i t h o g e n o u s i n p u t . Aluminium ( F i g . 3.4.6) i s g e n e r a l l y present i n higher c o n c e n t r a t i o n i n the dark l a y e r s , with the e x c e p t i o n of sample 66. The opal-^-free p r o f i l e shows t h a t l i g h t / d a r k v a r i a t i o n i s most n o t i c e a b l e between samples 55-65 and t h a t above sample 70, with the e x c e p t i o n of 75, there appears to be much l e s s v a r i a t i o n between samples and the A l c o n c e n t r a -t i o n i n the top of the core appears to be f a i r l y c onstant. I r o n - b e a r i n g mafic m i n e r a l s , such as hornblende, have been r e c o g n i s e d i n XRD s p e c t r a o f sediments from other p a r t s of the I n l e t (Francois 1987); however, no evidence of them was found i n the sediments from t h i s c o r e . The p r o f i l e of Fe i s presented i n F i g . 3.4.7. The main i r o n - b e a r i n g min-e r a l seen i n the XRD data i s c h l o r i t e . I r o n i s a l s o known to be p r e s e n t i n anoxic sediments as i r o n monosulphides and SAMPLE DEPTH (em) SAMPLE DEPTH (cm) Fig: 3 .4 .7MAJ0R ELEMENTS. % BY WEIGHT Fe . c m i ISI M. wonooncrocforv M I u i n o c f f M . 2.1 Z3 2£ 2.7 i» 3.1 i3 ifi 3.7 X BY WEIGHT. Fig: 3.4.7b IRON, O P A L - F R E E X RON SAMPLE NUMBER SAMPLE NUMBER 31 CO * CD > Q o' SAMPLE DEPTH (cm) i — 1 — 1 — 1 — 1 — 1 — 1 — 1 — 1 — 1 — i — 1 — 1 — i — r O 3 > » M O 05 0» *. K) o ™ ** " SAMPLE DEPTH (cm) •si - f c 7 5 p y r i t e ; however, no r e l a t i o n s h i p was observed between Fe and S and i t seems t h a t the major c o n t r o l on Fe i n these sediments i s i t s a s s o c i a t i o n with a l u m i n o s i l i c a t e s . The Fe:Al r a t i o of the sediments has a mean value of 0.64 ( F i g . 3.4.8). Clapp (1913) r e p o r t s Fe and A l v a l u e s i n the rocks c r o p p i n g out around F i n l a y s o n Arm with r a t i o s of between 0.4 and 0.7; thus the sediment values are c l o s e to those of the l o c a l source r o c k s . There i s , however, a n o t i c e a b l e t r e n d i n the p r o f i l e of the Fe:Al r a t i o and t h i s i n d i c a t e s t h a t there was a decrease i n the i n p u t of Fe not a s s o c i a t e d with c l a y m i n e r a l s between samples 55-75 compared to the v a l u e s a t the top and bottom of the core. T h i s i n d i c a t e s t h a t there i s an e x t r a input of Fe a t the top and bottom of the core. At the top of the c o r e , the i n c r e a s e appears to begin between samples 70-75 and t h i s i s c o i n c i d e n t with the decreased S i : A l r a t i o and lower water contents (see s e c t i o n 3.1.2). These o b s e r v a t i o n s a l l l e a d to the c o n c l u s i o n t h a t there i s a change i n sediment type a t t h i s p o i n t and t h a t the younger sediment c o n t a i n s higher amounts o f Fe, lower S i and has a lower p o r o s i t y . The p o i n t a t which these changes are seen i s c o i n c i d e n t with the p o i n t a t which l a y e r s became d i f f i c u l t to sample. The i n c r e a s e d Fe a t the base of t h i s core may a l s o i n d i c a t e a change i n sediment type. The K content o f the sediments w i l l be mainly l i n k e d to the amount o f a l k a l i f e l d s p a r and i l l i t e . The amount o f i l l i t e i n the XRD data was s m a l l and i n most samples a d i s t i n c t peak c o u l d not be measured. However, the Fig; 3.4.10 M A J O R E L E M E N T S . % B Y W E I G H T K . Scffwnt ConoflntastfoA. Soft CorflBctsd. os aa Q.7 as o.» i X BT WEIGHT. Fig: 3.4.10b P O T A S S I U M , O P A L - F R E E 0.76 OSS OAS 10S 1.15 X POTASSUM SAMPLE NUMBER Sampt* numbar. 78 p r o f i l e o f K ( F i g . 3.4.9) shows t h a t there are some l a r g e changes i n K and the peaks do correspond with those samples i n which a stronger i l l i t e peak was p r e s e n t (samples 85,83,73,64,59,52,50). Sediment t r a p data c o l l e c t e d i n the I n l e t r e p o r t e d by Francois (1987) showed t h a t the input o f i l l i t e i s c o ncurrent with the entrainment o f the F r a s e r R i v e r plume d u r i n g the summer months and i t may be t h a t i l l i t e peaks a t t h i s end o f the I n l e t are the r e s u l t o f p a r t i c u l a r l y s t r o n g i n c u r s i o n s o f F r a s e r R i v e r water i n t o Saanich I n l e t or of p a r t i c u l a r l y s t r o n g f l u s h i n g events t r a n s p o r t i n g the i l l i t e from the s i l l . V a r i a t i o n between l i g h t and dark l a y e r s i s g e n e r a l l y random; however, there i s a s e c t i o n between samples 55-64 i n which there does appear to be a seasonal s i g n a l . N e i t h e r the K p r o f i l e nor t h a t o f the K:A1 r a t i o (Fig.3.4.10) shows any d i s t i n c t t r e n d t h a t can be l i n k e d to a d i f f e r e n t sediment type i n the c o r e - t o p , although there i s a sharp drop i n the K:A1 r a t i o between samples 73-75. Otherwise, K:A1 v a l u e s are g e n e r a l l y w i t h i n the range o f the l o c a l r o c k s (Clapp, 1913). The decreased K:A1 r a t i o i s a t a minimum i n sample 75. Aluminium, Fe and T i a l l show i n c r e a s e d v a l u e s i n t h i s sample and i t i s a l s o seen to have a high q u a r t z : c h l o r i t e r a t i o which i s taken to i n d i c a t e a c o a r s e - g r a i n e d sediment. The drop i n the K:A1 r a t i o must i n d i c a t e t h a t t h i s sample i s low i n i l l i t e . T itanium i s known to be a s s o c i a t e d with d e t r i t a l c l a y s (Spears and Kanaris-Sotiriou, 1976) and with some heavy m i n e r a l s , such as r u t i l e . The p r o f i l e o f t h i s element 79 Fig: 3 . 4 . 1 2 T I T A N I U M : A L U M 1 N I U M R A T I O 0.022 0.026 0.03 0.034 0.038 0.042 0.046 0.05 0.064 Ti:M Fig: 3.4.13 M A G N E S I U M i A L U M I N I U M R A T I O m DARK S A M P L E MgiAl 8 0 ( F i g . 3.4.11) shows r e l a t i v e l y small v a r i a t i o n with a marked change a t sample 75. Below t h i s sample, T i c o n c e n t r a t i o n s are seen to be higher i n the dark l a y e r s , which i s c o n s i s t e n t with t h e i r f ormation as a r e s u l t o f winter r u n o f f . Above t h i s l e v e l t h i s d i s t i n c t i o n i s no longer e v i d e n t , and the T i c o n c e n t r a t i o n s are g e n e r a l l y higher and much more homogeneous than the samples lower i n the co r e . The i n c r e a s e d input o f T i i n the top o f the core i s c l e a r l y seen i n the T i : A l r a t i o ( F i g . 3.4.12), which shows valu e s ranging from 0.022 to 0.054. These are i n agreement with the value s f o r the l o c a l r o c k s , 0.02 f o r the C o l q u i t z g n i e s s , p a r t o f the J u r a s s i c metamorphic complex c r o p p i n g out along F i n l a y s o n Arm, and 0.05 f o r the Wark g n i e s s {Clapp, 1913). However, the i n c r e a s i n g r a t i o a t the co r e - t o p i m p l i e s an a d d i t i o n o f T i i n a s s o c i a t i o n with the proposed change i n sediment type. Spears and Kanaris-Sotiriou (1976) have shown a p o s i t i v e r e l a t i o n s h i p between the T i : A l r a t i o and qu a r t z content o f s h a l e s and argue t h a t t h i s i s r e l a t e d to g r a i n -s i z e . However, the low value o f t h i s r a t i o i n sample 62 i s matched by a high q u a r t z i c h l o r i t e r a t i o i n d i c a t i n g high q u a r t z , and the i n c r e a s e d T i : A l r a t i o a t the co r e - t o p i s matched by a d e c r e a s i n g S i : A l r a t i o . The i n c r e a s e d input o f T i i s seen to be g i n a t sample 70, although the l a r g e s t i n c r e a s e occurs i n the c o a r s e - g r a i n e d sediment i n sample 75. The o p a l - f r e e Ca p r o f i l e ( F i g . 3.4.13) shows t h a t there does not appear to be any r e g u l a r p a t t e r n o f v a r i a t i o n between l i g h t and dark l a y e r s . The p r o f i l e i s c h a r a c t e r i s e d 81 Fig: 3.4.14 MAJOR ELEMENTS. % BY WEIGHT Co Element concentration. Salt Corrected. H 1 1 B "* r i —I 1 1 1 1 1 1 1 1 1-2 1.6 2 2.4 24 3.2 3.6 X BY WEIGHT Fig: 3.4.14b CALCIUM, O P A L - F R E E Fig: 3.4.15 MAJOR ELEMENTS. % BY WEIGHT Mg. n i !»•... 11 1-.jlH • * > * IA Z1 2J 2£ 2.7 2A X BY WEIGHT. Fig: 3.4.15b MAGNESIUM, OPAL-FREE Z2 2A 3 3.4 34 4.2 4.6 6 6.4 X MAGNESIUM by a very high peak i n sample 55, which i s not matched by an i n c r e a s e i n carbonate, and the i n c r e a s e d v a l u e s a t the c o r e -top which are thought to be a s s o c i a t e d with carbonate. I t seems t h a t below sample 70, the Ca input i s f a i r l y c o n s t a n t , with the e x c e p t i o n o f sample 55, and i t i s l i k e l y t h a t t h i s element i s c o n t r o l l e d by i t s a s s o c i a t i o n with p l a g i o c l a s e f e l d s p a r . Magnesium i s s u b j e c t to a l a r g e c o r r e c t i o n because of the content o f t h i s element i n s a l t . The Mg p r o f i l e ( F i g . 3.4.14) does have some s i m i l a r i t i e s with the c h l o r i n e p r o -f i l e i n s e c t i o n 3.1. However, c h l o r i n e was determined with reasonably good p r e c i s i o n by wet chemistry (see Appendix D) so t h a t the numbers are c o n s i d e r e d to be r e l i a b l e . The v a l u e s are seen to decrease c o i n c i d e n t with the decrease i n S i and the i n c r e a s e d v a l u e s o f Fe and T i . T h i s decrease i s a l s o r e f l e c t e d i n the Mg:Al r a t i o shown i n F i g . 3.4.15. The p r o f i l e o f P i s shown i n F i g . 3.4.16. The p r e -c i s i o n of measurement o f t h i s element i s poor because of i t s low content i n these sediments. Phosphorus i s g e n e r a l l y a s s o c i a t e d with o r g a n i c carbon s i n c e i t i s an e s s e n t i a l n u t r i e n t f o r l i f e p r o c e s s e s . Samples 68,69 and 58 do show high v a l u e s of P and these are matched by high o r g a n i c c a r -bon content. However, other samples with high carbon do not show peaks i n P and the c o r r e l a t i o n between P and o r g a n i c carbon was very poor. The C:P weight r a t i o i s around 41, which i s the value a s c r i b e d to average p l a n k t o n but higher than the value of 24 a s c r i b e d to diatomaceous plankton 8 4 Fig: 3 .4 .16 M A J O R E L E M E N T S . % B Y W E I G H T P . Qoroont Concentration^ Soft Corrected* RSD 2CT 0.08 0.1 0.12 0.14 X BY WEKXT. Fig: 3 .4 .16b P H O S P H O R U S , O P A L - F R E E X PHOSPHORUS CARBON:PHOSPH0RUS 8 6 (Calvert, 1976). The p r o f i l e o f t h i s r a t i o i s shown i n F i g . 3.4.17 and i s seen to be f a i r l y c o nstant with higher r a t i o s being found i n the l i g h t l a y e r s . Sample 56 stands out i n t h i s p r o f i l e with a very high r a t i o . T h i s sample c o n t a i n s the h i g h e s t o r g a n i c carbon content found i n t h i s core. T h i s r a t i o i s s u b j e c t to a number o f v a r i a b l e s , such as g r a z i n g and b a c t e r i a l decomposition, which w i l l a f f e c t the r e g e n e r a t i o n o f these elements. Phosphorus i s g e n e r a l l y r e c y c l e d f a s t e r than carbon (.Calvert, 1976) and thus the high r a t i o s i n t h i s core might simply r e f l e c t the r a p i d r e c y c l i n g o f P w i t h i n the water column. In summary, the p r o f i l e s o f A l , F e , T i and K show some i n t e r e s t i n g f e a t u r e s i f the l i g h t and dark l a y e r s are compared. In a l l cases there appears to be a change i n the v a r i a t i o n between the l a y e r s a t around sample 70. Below t h i s sample, a l l these elements tend to have higher v a l u e s i n the dark l a y e r s which i s c o n s i s t e n t with t h e i r d e p o s i t i o n d u r i n g the winter maxima i n land r u n o f f , although t h i s d i s t i n c t i o n i s most n o t i c a b l e above sample 55. In the same s e c t i o n . S i and the S i : A l r a t i o are higher i n the l i g h t l a y e r s which i s taken to r e f l e c t higher c o n c e n t r a t i o n s o f opal i n these sam-p l e s and supports the idea t h a t they r e p r e s e n t summer d e p o s i t i o n . I t t h e r e f o r e appears t h a t the geochemical v a r i a t i o n o f the major elements i n the lower p a r t o f the core i s the s o r t expected i f the samples are r e f l e c t i n g seasonal d i f f e r e n c e s and i f p a i r s o f laminae r e p r e s e n t annual sedimentation. T h i s o b s e r v a t i o n supports the two Table IX Minor Element c o n c e n t r a t i o n s . Values l n ppm. SMPL DEPTH Ba Cr Cu Mn Mo Nl Pb Rb Sr V ¥ Zn Zr 86 0 307 84 38 5273 74 85 3.8 370 86 56 8398 93 84 4.2 381 80 55 7990 81 83 6.4 361 79 50 4206 82 82 7.5 338 76 46 6000 77 81 7.7 357 82 55 1880 95 80 9.5 384 81 47 1137 101 79 9.8 402 78 40 772 98 78 10.9 382 73 59 795 93 77 11.3 427 84 51 789 103 76 11.5 409 76 54 753 85 75 11.8 421 76 53 835 90 74 12.7 392 72 42 732 85 73 13. 3 439 85 60 851 107 72 14.1 345 72 43 513 97 71 15.4 401 64 36 541 91 70 16. 2 454 76 47 626 97 69 17.1 407 68 36 531 100 68 18. 3 331 57 16 391 96 67 18.7 433 75 45 535 102 66 18.9 441 72 40 466 103 65 19.5 445 73 43 612 115 64 19.7 371 56 27 401 104 63 19.9 401 61 34 502 96 62 20.6 326 62 21 458 77 61 21.1 455 74 37 636 101 60 22.4 340 56 19 368 109 59 22.6 449 76 39 556 146 58 23.2 304 60 21 341 120 57 24. 3 423 86 40 582 110 56 27. 2 316 67 31 373 86 55 27.7 412 77 43 614 93 54 28.4 391 72 41 518 78 53 29.7 432 74 41 571 93 52 30.6 356 66 32 504 82 51 31.6 430 80 34 573 97 50 32. 2 399 71 42 440 86 * A l l va lues are s a l t c o r r e c t e d 1. * Values shown are the mean of three 24 42 28 143 68 16 154 73 31 59 31 160 78 15 218 74 33 43 29 161 79 19 214 76 26 39 31 146 77 14 181 69 46 24 26 141 63 15 163 67 26 27 29 152 69 17 173 73 23 18 31 146 63 13 159 71 23 24 24 121 63 11 154 64 25 18 29 132 62 15 149 69 23 10 33 146 66 15 152 72 26 14 32 128 58 14 143 169 31 7 29 152 64 15 134 72 24 16 23 118 52 13 122 67 33 16 27 161 70 17 158 74 20 9 24 102 46 13 106 61 21 10 28 106 50 12 104 64 28 7 25 139 61 13 116 68 23 5 27 128 54 14 108 70 19 3 21 92 36 13 84 60 23 10 27 129 60 14 106 70 21 2 27 109 60 13 103 69 26 2 34 147 67 15 108 74 18 6 23 108 38 11 85 74 24 13 21 136 54 16 108 70 21 4 24 92 49 10 89 60 27 18 27 129 66 19 107 68 12 3 22 71 33 10 77 58 23 13 34 136 63 13 105 73 11 12 23 87 31 11 70 53 29 13 28 131 66 15 98 67 18 10 24 102 48 14 78 61 27 8 31 132 72 17 95 69 24 2 24 107 62 16 87 66 29 5 30 126 71 14 93 70 26 8 25 124 55 15 81 69 32 10 35 137 72 16 96 75 29 8 21 117 50 15 92 65 measuring c y c l e s . 88 sediment models proposed to e x p l a i n the measured **°Pb a c t i v i t y i n these sediments (see s e c t i o n 3.1). The seasonal nature o f the lamina samples, a t l e a s t w i t h i n the lower h a l f of the r e p o r t e d s e c t i o n , i s a l s o supported by both the minor element data ( s e c t i o n 3.5) and by the diatom data ( s e c t i o n 3.6). Note a l s o t h a t the r e g u l a r v a r i a t i o n between the samples breaks down a t the bottom of the core, and t h a t samples 55-50 do not show such c l e a r d i f f e r e n c e s between l i g h t and dark l a y e r s . T h i s i m p l i e s t h a t a c l e a r seasonal s i g n a l i s o n l y present i n the middle s e c t i o n o f the core. There was an enrichment of i r o n i n t h i s s e c t i o n but, u n l i k e the c o r e - t o p , no i n c r e a s e i n T i or decrease i n S i was seen. Above sample 70 the l i t h o g e n o u s elements A l , Fe, T i and K show d i s t i n c t l y d i f f e r e n t p r o f i l e s and the S i and Mg contents o f the sediment decrease. The d i s t i n c t i o n between l i g h t and dark samples i s no longer obvious and the c o n c e n t r a t i o n d i f f e r e n c e s between samples are reduced. Potassium i s an e x c e p t i o n i n t h a t there are some l a r g e v a r i a t i o n s i n i t s c o n c e n t r a t i o n w i t h i n t h i s s e c t i o n . S i l i c o n , A l , F e , and T i a l l show higher c o n c e n t r a t i o n s i n sam-p l e 75 and the q u a r t z : c h l o r i t e r a t i o i s e x c e p t i o n a l l y high i n t h i s sample. Potassium does not show higher c o n c e n t r a t i o n s i n sample 75 and the K:A1 r a t i o shows the lowest value i n the core i n d i c a t i n g t h a t there was perhaps l i t t l e i l l i t e i n t h i s c o a r s e - g r a i n e d sample. This change i n the p r o f i l e s around samples 70-75 c o i n c i d e s with the p o i n t a t which the l a y e r s were seen to 8 9 become i n d i s t i n c t d u r i n g sampling and i t i s proposed t h a t there i s a change i n sediment type and s e d i m e n t a t i o n r a t e (see s e c t i o n 3.1) a t t h i s p o i n t . The new sediment i s thought to have lower c o n c e n t r a t i o n s of S i and Mg while Fe and T i are e n r i c h e d . The c h l o r i n i t y p r o f i l e appears to i n d i c a t e t h a t t h i s sediment a l s o has a lower p o r o s i t y and, s i n c e no d i s t i n c t i o n can be made from the XRD s p e c t r a , the new sediment components are p o o r l y c r y s t a l l i n e . The most l i k e l y source f o r such a sediment i s the Bamberton cement works; however, the i n c r e a s e i n Fe and T i begins lower i n the sediment column than the observed i n c r e a s e i n carbonate. F i n i s h e d cement i s l i k e l y to be p o o r l y c r y s t a l l i n e and i s known to c o n t a i n Fe. However, i t a l s o c o n t a i n s S i and A l i n much l a r g e r q u a n t i t i e s and these elements do not show the i n c r e a s e t h a t an input of cement would cause. 3.5 The geochemistry o f minor elements. The geochemistry o f t r a c e or minor elements i n Saanich I n l e t was f i r s t examined by Gross (1967) arid has r e -c e n t l y been s t u d i e d i n d e t a i l by Francois (1987). The con-c e n t r a t i o n s of any minor element such as Ba,Cr,Cu,Ni,Pb,Rb,Sr,V,Y,Zr and Zn have been shown i n past s t u d i e s of nearshore sediments to be s t r o n g l y c o r r e l a t e d with the i n p u t o f d e t r i t a l l i t h o g e n o u s m a t e r i a l (Hirst, 1962b; Calvert, 1976). The reason f o r t h i s c o r r e l a t i o n i s t h a t they s u b s t i t u t e f o r major elements w i t h i n the l a t t i c e s of a l u m i n o s i l i c a t e m i n e r a l s (Krauskopf, 1979). In Saanich I n l e t , Francois (1987) has shown t h a t some of these elements are a l s o e n r i c h e d i n the diatomaceous anoxic muds of the c e n t r a l b a s i n . He showed t h a t V,Ni,Cr and perhaps Cu are en-r i c h e d because of d i a g e n e t i c processes, while Zn,Ni and Cu are a l s o probably e n r i c h e d because o f t h e i r c h a l c o p h i l e na-t u r e and the d e p o s i t i o n o f s u l p h i d e s w i t h i n these anoxic sediments. He a l s o found t h a t the enrichments were much g r e a t e r i n the sediments o f F i n l a y s o n Arm. T h i s i s probably a t t r i b u t a b l e to the s t r o n g r e d u c i n g c o n d i t i o n s i n these sed-iments (Gross and Gucluer, 1964) and to lower sedim e n t a t i o n r a t e s a t t h i s end of the I n l e t , which causes l e s s d i l u t i o n of d i a g e n e t i c a l l y mobile elements by l i t h o g e n o u s and biogenous components. The study o f the d i s t r i b u t i o n of these minor e l e -ments i n t h i s core i s hampered by a number of f a c t o r s . F i r s t l y , the range of c o n c e n t r a t i o n s observed i s g e n e r a l l y s m a l l , making the d e t e r m i n a t i o n o f any r e l a t i o n s h i p s between elements d i f f i c u l t . Francois (1987) s t u d i e d the f u l l range of sediment types w i t h i n the I n l e t so t h a t a much wider range o f v a r i a t i o n was observed. Secondly, no data were a v a i l a b l e f o r the minor element c o n c e n t r a t i o n s of the p u r e l y l i t h o g e n o u s input i n t o the I n l e t and thus changes i n the c o n t r i b u t i o n of t e r r i g e n o u s m a t e r i a l to the laminae c o u l d not be d e f i n i t i v e l y i d e n t i f i e d . The nature o f the laminae themselves i s a l s o q u e s t i o n a b l e (see s e c t i o n 3.1) and d i f f e r e n c e s i n the c o n c e n t r a t i o n o f most minor elements between the l i g h t and dark l a y e r s i s g e n e r a l l y w i t h i n the 2 91 Flo: 3.5.2 BARIUM : POTASSIUM RATIO 3 6 0 4 0 0 4 4 0 4 8 0 520 5 6 0 6 0 0 6 4 0 6 8 0 720 e r r o r . However, i t w i l l be shown t h a t there does appear to be a seasonal s i g n a l i n the p r o f i l e s o f some elements and t h a t the minor elements g e n e r a l l y support the p r o p o s i t i o n t h a t there are two d i f f e r e n t sediment regimes w i t h i n the r e p o r t e d s e c t i o n o f t h i s c o r e . The minor element data are presented i n Table IX. Many of the elements (Cr,Ni,Rb,Sr, V and Y) had p r o f i l e s which decreased to minimum valu e s c o i n c i d e n t with high c o n c e n t r a t i o n s o f opal and t h e r e f o r e the p r o f i l e s presented here have been c o r r e c t e d f o r d i l u t i o n by o p a l . The f i r s t s e c t i o n d i s c u s s e s the a b s o l u t e abundances o f the t r a c e elements and i s f o l l o w e d by a s e c t i o n d e s c r i b i n g t h e i r r a t i o s to A l . 3.5.1 Absolute abundances of minor elements. Barium i s known to s u b s t i t u t e f o r K i n K - f e l d s p a r s and micas. The p r o f i l e o f t h i s element ( F i g . 3.5.1) shows t h a t v a l u e s are g e n e r a l l y higher i n the dark l a y e r s , with the e x c e p t i o n o f samples 70 and 66. Values are seen to show v a r i a t i o n s between l i g h t and dark samples u n t i l sample 79, when the seasonal s i g n a l appears to break down. There i s a s i g n i f i c a n t drop i n the Ba content of the sediments i n the top of the core which i s c o i n c i d e n t with the i n c r e a s e i n carbonate d e s c r i b e d i n s e c t i o n 3.3. Sample 70 has the h i g h e s t Ba c o n c e n t r a t i o n which appears to be unusual f o r a l i g h t l a y e r . SAMPLE NUMBER SAMPLE NUMBER 94 Previous work has i n d i c a t e d a p o s s i b l e l i n k be-tween Ba and the opal content of sediments (Goldberg and Arrhenius,1958; Brongersma-Sanders et al. 1980), although whether the Ba was d i r e c t l y a s s o c i a t e d with the opal or i f b a r i t e was produced i n the s o f t t i s s u e s o f the diatoms was not known. Calvert and Price (1983) saw no c o r r e l a t i o n between high opal contents and Ba i n the inshore areas of the Namibian s h e l f , the h i g h e s t Ba c o n c e n t r a t i o n s being l o c a t e d a t the outer edge o f the s h e l f . Fresnel et al. (1979) have shown t h a t Ba i s c o n c e n t r a t e d by prymnesiophyte f l a g e l l a t e s and c u l t u r e s t u d i e s on the genus Pavlova have confirmed t h i s (Calvert, unpublished d a t a ) . Schmitz (1987) has argued t h a t Ba enrichments i n e q u a t o r i a l r e g i o n s i s a s s o c i a t e d with zones of high p r o d u c t i o n . The p l o t of the Ba:K r a t i o (Fig.3.5.2) shows a maximum i n the middle s e c t i o n of the core c o i n c i d e n t with the opal maximum ( F i g . 3.2.4). T h i s should not, however, be taken as i n d i c a t i v e o f enrichment by diatoms s i n c e f l a g e l l a t e s are thought to be important c o n t r i b u t o r s to primary p r o d u c t i o n i n BC i n l e t s (Harrison et al. 1983) and i t i s proposed t h a t the Ba enrichment simply i n d i c a t e s a time of higher p r o d u c t i o n . The Ba:K p r o f i l e a l s o shows v a r i a t i o n between l i g h t and dark l a y e r s i n samples 59-65 with the l i g h t l a y e r s having the higher r a t i o expected i f Ba i s indeed l i n k e d to primary p r o d u c t i o n . Sample 70, which has unusual c o n c e n t r a t i o n s of a number of minor elements, a l s o has a h i g h Ba:K r a t i o . With the e x c e p t i o n of sample 75, which showed peaks i n some of the major elements, the upper sediment i s c h a r a c t e r i s e d by a steady decrease i n the Ba:K r a t i o and t h i s might be i n d i c a -t i v e of d e c r e a s i n g primary p r o d u c t i o n . Lower r a t i o s are a l s o observed i n the bottom o f the core, which might mean that longer term p r o d u c t i o n c y c l e s occur a t t h i s end of Saanich I n l e t , l e n d i n g support to a f u r t h e r change i n sedimentation w i t h i n the l a s t few samples at the base o f the core. Chromium s u b s t i t u t e s f o r Fe and Mg i n mineral l a t -t i c e s . Hirst (1962b) argued t h a t the s u b s t i t u t i o n i s most n o t i c e a b l e i n i l l i t e but t h a t s u b s t i t u t i o n i n montmoril-l o n i t e a l s o o c c u r s ; however, both these m i n e r a l s are minor components of Saanich I n l e t sediments. The p r o f i l e of Cr i s shown i n F i g . 3.5.3 and the Cr:Fe r a t i o i s presented i n F i g . 3.5.4. Chromium valu e s are g e n e r a l l y higher i n the dark l a y e r s , although sample 70 i s a g a i n seen to be unusual i n t h a t i t has a high Cr c o n c e n t r a t i o n . Since the Fe p r o f i l e shows no s y s t e m a t i c v a r i a t i o n , the i n c r e a s e d Cr:Fe r a t i o i n the c e n t r e o f the core i n d i c a t e s t h a t t h i s element i s a l s o e n r i c h e d where opal v a l u e s are higher. Higher Cr:Fe r a t i o s are seen i n the l i g h t l a y e r s between samples 55-65, and the r a t i o i s seen to f a l l a t the base o f the core. Francois (1987) has shown through a c o r r e l a t i o n between the Cr:Mg r a t i o and o r g a n i c carbon t h a t t h i s element i s indeed e n r i c h e d i n sediments c o n t a i n i n g high carbon. Copper i s thought to be added to a n o x i c sediments by p r e c i p i t a t i o n of CuS or by a s s o c i a t i o n with o r g a n i c matter (Doff, 1969; Calvert, 1976). The p r o f i l e of Cu ( F i g . Fig: 3 . 5 . 5 C O P P E R Opal Corrected RSD 2tr PPM COPPER F i g : 3 . 5 . 6 M A N G A N E S E Opal Corrected RSD 2CT (Thoiaanda) PPM MANGANESE Fig: 3.5.7 MOLYBDENUM PPM MOLYBDENUM Fio: 3 . 5 . 8 NICKEL Opal Cocrtto&vrj RSD 20" PPM NICKEL 98 3.5.5) shows t h a t there appears to be an i n c r e a s e towards the top of the core s t a r t i n g a t sample 70. V a r i a t i o n between samples appears to show no t r e n d , although there are gener-a l l y h igher values i n dark l a y e r s i n d i c a t i n g t h a t Cu might not be a s s o c i a t e d with carbon d e r i v e d from p r o d u c t i o n . No c o r r e l a t i o n was found between t h i s element and o r g a n i c carbon. Manganese, although o f t e n c o n s i d e r e d to be a major element i n rocks and sediments, i s c o n s i d e r e d a t r a c e e l e -ment i n t h i s study because o f i t s low c o n c e n t r a t i o n compared to other major elements. The p r o f i l e o f Mn i s shown i n i n F i g . 3.5.6; a st r o n g enrichment o f t h i s element i s presen t i n the s u r f a c e sediments o f the core. Mn oxides are gener-a l l y reduced to Mn2* under anoxic c o n d i t i o n s and t h i s d i s -s o l v e d s p e c i e s i s r e t a i n e d i n the bottom waters (Grill, 1982). T h i s normally means t h a t c h a r a c t e r i s t i c c o n c e n t r a -t i o n s o f Mn i n anoxic sediments, u n l e s s p r e c i p i t a t i o n o f manganoan carbonate (Mn n.Ca„.C0») o c c u r s , are those t y p i c a l of a l u m i n o s i l i c a t e s . In Saanich I n l e t , t h i s appears to be approximately 500 ppm. The Mn peak i n t h i s core may be a c -counted f o r i f the top o f the core i s c o n s i d e r e d to be o x i c as the r e s u l t o f a f l u s h i n g event which has been seen to generate f l o e s o f MnOa (Grill, 1982; F r a n c o i s , 1987). However, no oxygen was measured i n water samples o f the I n l e t bottom waters c o l l e c t e d from water c a s t s taken d u r i n g the same c r u i s e as t h i s core was c o l l e c t e d . There i s a l s o no evidence, g i v e n the p r o f i l e o f Mn lower i n the core, t h a t 99 high Mn v a l u e s , due to Mn oxides p r e c i p i t a t e d d u r i n g f l u s h i n g events, are preserved upon b u r i a l i n these anoxic sediments and i t has been argued t h a t the recovered i n t e r f a c e c o n s i s t s of sediments 20 years o l d . Another e x p l a n a t i o n f o r the high Mn v a l u e s i n the co r e - t o p i s t h a t Mn has been f i x e d i n the sediments by the p r e c i p i t a t i o n of Mn carbonate (Doff, 1969; Calvert, 1976; Pedersen and Price, 1982). The Mn peak i s c o i n c i d e n t with the i n c r e a s e i n carbonate ( F i g . 3.3.1); however, the p r e c i p i t a t i o n of Mn carbonate r e q u i r e s an o x i c top to the sediments i n order f o r Mn to be *pumped' i n t o the pore-waters where high c o n c e n t r a t i o n causes the carbonate p r e c i p i t a t i o n . High pore water c o n c e n t r a t i o n s of Mn are r e -ported i n outer f j o r d sediments i n Norway where r h o d o c h r o s i t e i s observed (Hamilton-Taylor and Price, 1983). T h i s i s not thought to be the case i n these sediments because o f the anoxic nature of the bottom waters and s i n c e no evidence o f a long term change i n these c o n d i t i o n s can be found. T h i s l e a v e s the p o s s i b i l i t y t h a t the enrichments are caused by high Mn v a l u e s a s s o c i a t e d with the dust-dump from the Bamberton works. Manganese has been r e c o g n i s e d as an anthropogenic p o l l u t a n t i n sediments o f C a l i f o r n i a by Bruland et al.(1974). I t i s a l s o i n t e r e s t i n g to note t h a t Mn i n c r e a s e s s l i g h t l y between sample 72-73, c l o s e to the p o i n t a t which there i s a proposed change i n the sediment type. The p r o f i l e of Mo i s shown i n F i g . 3.5.11. This i s an incompatible element and i t s l a r g e degree of enrichment 100 F i g : 3 .5 .9 RUBIDIUM Opal Corrected H—*—I I I P f ^ P l I I I I I I I—I 1 1 1 r 2 8 3 0 3 2 3 4 3 6 3 6 4 0 42 4 4 4 8 4 8 PPM RUBtDUM F i g : 3 .5 .10 STRONTIUM Opal Corrected RSD 2er 120 140 160 180 200 220 240 PPM STRONTUM 101 i n a noxic sediments (a t y p i c a l c r u s t a l value i s 1.5 ppm Kraaskopf, 1979) i s the r e s u l t of d i a g e n e t i c enrichment (Gross, 1967; Doff, 1969; Calvert, 1976; Francois, 1987). Berrang and Grill (1974) have suggested t h a t Mo i s t r a n s -p o r ted i n t o the anoxic bottom water of Saanich I n l e t i n a s s o c i a t i o n with Mn oxide f l o e s which are r e d i s s o l v e d i n the bottom waters. However, the enrichment i n the sediments i s brought about e i t h e r through c o p r e c i p i t a t i o n with FeS or through a scavenging process i n v o l v i n g o r g a n i c carbon Calvert (1976). An i n t e r e s t i n g f e a t u r e o f the Mo p r o f i l e i s the peak between samples 55 and 60. Since Mo i s thought to be a good i n d i c a t o r of r e d u c i n g anoxic c o n d i t i o n s , i t may be t h a t t h i s peak r e f l e c t s s t r o n g e r anoxic c o n d i t i o n s i n F i n l a y s o n Arm a t t h a t time. The Mo maximum does, however, match the h i g h e s t amounts o f o r g a n i c carbon i n the core, and no c o r r e l a t i o n between Mo and carbon or S c o u l d be found u s i n g a l l the data p o i n t s . The p r o f i l e o f Ni ( F i g . 3.5.8) shows t h a t the c o n c e n t r a t i o n o f t h i s element v a r i e s only s l i g h t l y through the s e c t i o n . Hirst (1962b) has shown t h a t there i s a c o r r e l a t i o n between Ni and heavy minerals i n c o a r s e - g r a i n e d sediments; however, the main i n f l u e n c e on t h i s element i n f i n e - g r a i n e d , o r g a n i c - r i c h sediments appears to be i t s a s s o c i a t i o n with o r g a n i c carbon (Calvert, 1976; Francois, 1987). Doff (1969) showed t h a t there i s no s i g n i f i c a n t enrichment o f Ni and l i t t l e d i f f e r e n c e i n c o n c e n t r a t i o n when o x i c and anoxic sediments i n Oslo F j o r d are compared. No 102 c o r r e l a t i o n was found between Ni and o r g a n i c carbon i n t h i s core and those samples with high o r g a n i c content, 56,58 and 60 (see F i g . 3.2.6) are seen to have low Ni c o n c e n t r a t i o n s . Rubidium i s c l o s e l y r e l a t e d to the K content o f sediments because o f i t s s u b s t i t u t i o n f o r t h a t element i n K-f e l d s p a r and micas and i s g e n e r a l l y higher i n the dark l a y e r s o f t h i s c o re. The p r o f i l e o f Rb ( F i g . 3.5.9) i s , however, q u i t e u n l i k e t h a t o f K ( F i g . 3.4.7) and a poor c o r r e l a t i o n was found between these elements, s u g g e s t i n g t h a t they r e s i d e i n d i f f e r e n t phases. I t i s l i k e l y , however, t h a t t h i s poor c o r r e l a t i o n i s a r e s u l t o f the narrow ranges of v a l u e s observed i n CPIV. Francois (1987) has shown a good r e l a t i o n s h i p between K and Rb i n sediments throughout Saanich I n l e t . Strontium i s mainly h e l d i n p l a g i o c l a s e f e l d s p a r s and c a l c i u m carbonate where i t s u b s t i t u t e s f o r Ca. However, Hawkesworth and Elderfield (1978) have shown t h a t the Sr content i s g r e a t l y reduced i n the r e c r y s t a l l i s a t i o n o f biogenous carbonate to limestone. Since the main source o f carbonate to these sediments i s limestone or cement dust from the Bamberton works, an o b s e r v a t i o n supported by the f a c t t h a t Sr does not show any i n c r e a s e i n a s s o c i a t i o n with the carbonate peak i n samples 80-86, and s i n c e there i s l i t -t l e i n p ut o f b i o g e n i c carbonate, the Sr c o n c e n t r a t i o n i n these sediments i s probably c o n t r o l l e d by f e l d s p a r . The p r o -f i l e o f Sr i s shown i n F i g . 3.5.10 and c o n c e n t r a t i o n s are seen to be higher i n the dark l a y e r s which i s c o n s i s t e n t Fig: 3.5.11 VANADIUM Opal Corrected M 06 76 86 06 PPM VANADIUM Fig: 3 . 5 . 1 2 VANADIUM-IRON RATIO RSD 2cr I 1 1 4 I I I I -J— | 1 1 1 1 1 1 13 16 17 18 21 23 26 27 VtFfc 104 with input d e r i v e d from r u n o f f . T h i s v a r i a t i o n breaks down above sample 76 and below sample 53 and sample 70 i s a g a i n seen to stand out as a l i g h t l a y e r with h i g h amounts of elements d e r i v e d from l i t h o g e n o u s i n p u t . T h i s p r o f i l e , together with t h a t of V (see f o l l o w i n g s e c t i o n ) supports the idea t h a t the laminae are r e f l e c t i n g seasonal i n p u t of l i t h o g e n o u s d e t r i t u s to the I n l e t . Vanadium shows the l a r g e s t v a r i a t i o n between sam-p l e s of any o f the minor elements. The V p r o f i l e ( F i g . 3.5.11) shows c o n s i s t e n t l y higher v a l u e s i n the dark samples, with the e x c e p t i o n o f samples 66,70 and those above sample 78. Th i s i s s i m i l a r to the v a r i a t i o n seen i n the p r o f i l e o f Sr. Calvert (1976) s t a t e s t h a t V i s e n r i c h e d i n anoxic sediments and Francois (1987) showed t h a t there i s an enrichment o f V i n the anoxic sediments of Saanich I n l e t , p a r t i c u l a r l y i n F i n l a y s o n Arm and a s t r o n g c o r r e l a t i o n between V and o r g a n i c carbon i n the c e n t r a l b a s i n , however, there i s a poor r e l a t i o n s h i p between these components i n t h i s c o re. Doff (1969), shows t h a t there i s no d i s t i n c t i o n between anoxic and o x i c sediments o f Oslo F j o r d on the b a s i s of t h e i r V content. Vanadium r e a d i l y s u b s t i t u t e s f o r Fe i n c h l o r i t e ; a p l o t of V:Fe ( F i g . 3.5.13) shows t h a t the seasonal s i g n a l i s p r e s e r v e d , with the e x c e p t i o n o f samples 56,62 and 70 which are l i g h t l a y e r s with a high r a t i o . T h i s i m p l i e s t h a t some o f the seasonal V s i g n a l must be produced by an a s s o c i a t i o n between V and another sediment component. 105 Fig: 3.5.13 Y T T R I U M Opal CofrecftBO1 RSD 2<T 14 16 18 20 22 24 26 PPM YTTRIUM Fig: 3.5.14 Z I N C Opot CorTOCvaKl RSD 2<T I MO 130 150 170 190 210 230 250 PPM ZMC Fig: 3.5.15 ZINCllRON RATIO 106 R S D 20" Znf* Fig: 3.5.16 LEAD, OPAL-FREE R S D 20-I PPM L E A D 107 The p r o f i l e of Y i s shown i n F i g . 3.5.14. This e l -ement i s known to be a s s o c i a t e d with heavy minerals where i t r e p l a c e s Ca. An i n t e r e s t i n g f e a t u r e of the Y p r o f i l e i s t h a t i t tends to show seasonal v a r i a t i o n i n s e c t i o n s of the core where l i g h t / d a r k v a r i a t i o n i n o r g a n i c carbon i s reduced. T h i s r e l a t i o n s h i p appears to h o l d below sample 70 and i s most n o t i c e a b l e between samples 50-55 and 60-65 where l a r g e v a r i a t i o n s i n the Y content are seen and where there i s l i t -t l e v a r i a t i o n i n o r g a n i c carbon between adj a c e n t samples. In these s e c t i o n s , the Y content of the dark l a y e r s i s higher and t h i s o b s e r v a t i o n l e a d s to the s u g g e s t i o n t h a t the Y s i g n a l , d e r i v e d from l i t h o g e n o u s m a t e r i a l , i s very s e n s i t i v e to d i l u t i o n by o r g a n i c carbon. T h i s p a t t e r n breaks down above sample 70 where v a r i a t i o n between l i g h t and dark l a y e r s i s more random, i n d i c a t i n g t h a t the change i n sedimentation d i s t u r b e d the v a r i a t i o n between Y and carbon. Z i n c c o n c e n t r a t i o n s ( F i g . 3.5.15) have been l i n k e d to the input of carbonate from the Bamberton Works. However, Zn i s a l s o thought to r e p l a c e Fe i n c h l o r i t e and can a l s o be d i a g e n e t i c a l l y e n r i c h e d i n o r g a n i c - r i c h sediments (Calvert, 1976) because of i t s a s s o c i a t i o n with o r g a n i c matter (Doff, 1969). No r e l a t i o n s h i p was seen between Zn and carbon i n these sediments and the p l o t of the Zn:Fe r a t i o ( F i g . 3.5.16) c l e a r l y shows i n c r e a s e d values from sample 55 to the core top, i n d i c a t i n g an e x t r a source of Zn to the sediments. T h i s source i s thought to be the Bamberton Quarry, s i n c e a 108 Fig: 3.5.17 ZIRCONIUM Opal Corractad RSO 20" PPM ZMCONUM 109 peak i s seen i n a s s o c i a t i o n with the carbonate maximum at the top of the core. A l t e r n a t i v e l y , the Zn p r o f i l e might be r e f l e c t i n g i n c r e a s i n g atmospheric p o l l u t i o n s i n c e the World War Two. Bruland et al. (1974) showed such i n c r e a s e s i n Zn c o n c e n t r a t i o n s i n sediments o f f C a l i f o r n i a . However, the beginning of the Zn i n c r e a s e a t sample 55 i s not matched by t h a t of Pb ( F i g . 3.5.16) which i s a l s o known to be an atmospheric p o l l u t a n t . The Pb i n c r e a s e c o i n c i d e s with the carbonate peak, but shows low and almost constant v a l u e s lower i n the core. However, there i s some evidence t h a t the i n c r e a s e s i n c o n c e n t r a t i o n of these two metals i n the atmosphere are not c o i n c i d e n t and t h a t Zn shows an e a r l i e r i n c r e a s e . In the sediments of the San Pedro b a s i n , f o r example, Pb i n c r e a s e s d r a m a t i c a l l y i n 1960, while Zn i n c r e a s e s i n 1940 IBruland et al., 1974). Zirconium occurs i n the mineral z i r c o n which i s g e n e r a l l y a s s o c i a t e d with c o a r s e - g r a i n e d sediments. The p r o f i l e o f t h i s element ( F i g . 3.5.18) shows low v a l u e s with the e x c e p t i o n of the dramatic i n c r e a s e i n sample 76. T h i s peak i s not matched by any other element and there i s no i n d i c a t i o n i n the S i : A l or q u a r t z : c h l o r i t e r a t i o s t h a t t h i s sample i s c o a r s e r g r a i n e d ; consequently no c l e a r explanaton can be g i v e n f o r t h i s peak. F i g : 3 .5 .18 B A R I U M : A L U M I N I U M R A T I O RSD 2<T BA:AL F i g : 3 . 5 .19 C H R O M I U M : A L U M I N I U M R A T I O CR:AL 111 3.5.2 R a t i o s of the t r a c e elements to aluminium. A l l o f the minor elements were r a t i o e d to the A l c o n c e n t r a t i o n of the samples so t h a t any enrichments or d e p l e t i o n s r e l a t i v e to the t r a c e element composition of the l i t h o g e n o u s a l u m i n o s i l i c a t e input to Saanich I n l e t might be seen. The data are shown i n F i g . 3.6.19-3.6.28; the p r o f i l e s l a r g e l y c o r r o b o r a t e the i n f o r m a t i o n d e r i v e d from the p r o f i l e s of a b s o l u t e abundance. Barium:aluminium (Fig.3.6.19) r e f l e c t s an enrichment of Ba t h a t i s c o i n c i d e n t with higher S i : A l r a t i o s and decreases above sample 70 i n c o n j u n c t i o n with the i n c r e a s e i n o r g a n i c carbon and the proposed change i n se d i m e n t a t i o n r a t e . The decrease lower i n the core i s c o i n c i d e n t with a change i n sedimentation. There i s some evidence (see the d i s c u s s i o n o f Fe i n s e c t i o n 3.4 and of Chaetoceros counts s e c t i o n 3.6) t h a t there may a l s o be a d i s t u r b a n c e to the sedimentary regime e v i d e n t a t the base of the core. The observed p r o f i l e seems to support a r e l a t i o n s h i p between Ba and primary p r o d u c t i o n and i m p l i e s g r e a t e r p r o d u c t i o n i n the middle of t h i s core. T h i s o b s e r v a t i o n supports the p o s s i b i l i t y t h a t there i s long term v a r i a t i o n (on the order of 10-15 y e a r s , based on the best estimate o f sedimentation r a t e ) i n p r o d u c t i o n w i t h i n Saanich I n l e t . The r a t i o s of Ba:Al, C r : A l , V:A1, S r : A l and N i : A l N i : A l ( F i g . 3.6.20, F i g . 3.6.25, F i g . 3.6.24, F i g . 3.6.22) 112 Fig: 3.5.21 NICKELALUMINIUM RATIO RSD 20" NIUU. 113 Fig: 3.5.22 RUBIDIUMrALU MINIUM RATIO 0-4.2 4.6 6 6.4 &8 6.2 6.6 7 7.4 RB:AL Fig: 3.5.23 STRONTIUM:ALUMINIUM RATIO RSD 2tr 114 are a l l higher i n sample 70 compared with the dark l a y e r s above and below. The seasonal s i g n a l i s not c l e a r i n p l o t s of these r a t i o s , whereas i n the a b s o l u t e abundance p r o f i l e s o f V and Sr, f o r example, do show a c l e a r seasonal v a r i a t i o n below sample 70. T h i s i m p l i e s t h a t the seasonal s i g n a l i n these elements i s d e r i v e d from t h e i r a s s o c i a t i o n with a l u m i -n o s i l i c a t e s and not from any other source. Those elements which are known to be c l o s e l y a s s o c i a t e d with a l u m i n o s i l i -c a t e i n p u t , Rb ( F i g . 3.6.23) and Y ( F i g . 3.6.26) show random v a r i a t i o n s and an e s s e n t i a l l y v e r t i c a l t r e n d i n the p r o f i l e s o f t h e i r r a t i o s to A l . Sample 70 thus appears to be the p o i n t a t which a change i n the p r o f i l e s o c c u r s . T h i s has a l s o been observed i n the p o r o s i t y data and i n the major element geochemistry and i s thought to be c o i n c i d e n t with a change both i n miner-alogy and sedimentation r a t e . Zincraluminium and Pb:Al ( F i g . 3.6.27 and F i g . 3.6.28 r e s p e c t i v e l y ) both show i n c r e a s e s c o i n c i d e n t with the dump of carbonate from Bamberton and a l s o to atmospheric p o l l u t i o n . These p r o f i l e s c o n f i r m t h i s , and support the idea t h a t Zn i n c r e a s e s because of anthropogenic input before those o f Pb (Bruland et al., 1974). The minor elements show some c l e a r d i s t i n c t i o n s between l i g h t and dark l a y e r s . T h i s i s e s p e c i a l l y e v i d e n t i n the bottom h a l f o f the core and i s most c l e a r i n the case of V and Sr. Barium i s e n r i c h e d i n a s e c t i o n o f the p r o f i l e thought to be c o i n c i d e n t with higher primary p r o d u c t i o n . Fig: 3.5.26 Z INC:ALUMINIUM RATIO 116 RSD 20" t- 1 ZN:AL Fio: 3.5.27 LEAD:ALUMIMIUM RATIO RSD 20" I 1 PBiAL. 117 Manganese r e f l e c t s an input i n a s s o c i a t i o n with the carbonate, p o s s i b l y as a p o l l u t a n t , and t h i s o b s e r v a t i o n together with decreased Ba:K r a t i o s and a decreased Mo content a l s o support the proposed change i n sediment above sample 70. The elements which do appear to show a s t r o n g seasonal s i g n a l , V and Sr, seem to show t h a t such a s i g n a l c o n t i n u e s above sample 70 and i s s t i l l apparent i n samples 77 and 78, which supports the idea t h a t the top sediment may indeed c o n t a i n laminae but t h a t they are on such a f i n e s c a l e t h a t they c o u l d not be sampled d i s c r e t e l y . 3.6 The diatom r e c o r d . 3.6.1 P r e p a r a t i o n of a p e e l s l i d e of the varves. Once the a i o P b dates f o r core CPIV became known, i t was necessary to v e r i f y the assumption t h a t the sediment laminae r e p r e s e n t e d true seasonal varves s i n c e t h e i r d i s c r e p a n c y with the a i o P b chronology meant t h a t they might r e p r e s e n t longer c y c l e s o f d e p o s i t i o n . To do t h i s , a s e c t i o n of the a r c h i v e m a t e r i a l from the base o f core CPIV where the laminae were d i s t i n c t was chosen f o r study . A s e c t i o n of t h i s m a t e r i a l was f r e e z e -d r i e d , which was found to preserve the sediment laminae, and a p e e l o f the sediment taken by touching the s u r f a c e of the d r i e d sediment with Scotch-tape. The tape was then mounted P L A T E II An example of a dark lamina. X400 S C A L E 0.1mm P L A T E III Example of a dark lamina containing some centr ic diatoms. X400 S C A L E 0.1mm on a microscope s l i d e u s i n g Hyrax and examined under the microscope. The m a t e r i a l on the s l i d e was too t h i c k to allow q u a n t i t a t i v e counts to be made, but the diatom f r u s t u l e s seen showed d i s t i n c t l a y e r s r e f l e c t i n g a seasonal s i g n a l i n t h e i r s p e c i e s s u c e s s i o n (C.Sancetta. pers comm). The seasonal s u c e s s i o n t h a t was observed i n these laminae i s i l l u s t r a t e d i n P l a t e s II-IX. P l a t e s II and I I I show t y p i c a l dark l a y e r s . These l a y e r s g e n e r a l l y c o n t a i n amorphous aggregates of m a t e r i a l and c o n t a i n few e a s i l y r e c o g n i s i b l e diatoms. T h i s d i s t i n c t i o n was not always so c l e a r - c u t and some dark l a y e r s were found which c o n t a i n e d spores, l a r g e C o s c i n o d i s c u s and T h a l a s s i o s i r a . as shown i n P l a t e I I I . P l a t e IV shows the j u n c t i o n between a dark l a y e r and the l i g h t l a y e r above i t (core-top i s always to the l e f t i n these photographs). Skeletonema costatum was seen to be-come more prominant i n the l i g h t l a y e r s and i n c r e a s e d numbers of T h a l a s s i o s i r a S P were a l s o seen. Skelotonema costatum sometimes becomes completely dominant and P l a t e V i s a good example of a c l e a r bloom of t h i s s p e c i e s . S.costatum, although i t i s common throughout the year, i s g e n e r a l l y thought to bloom i n the s p r i n g (Takahashi et al. 1977). This has been shown by Stockner et al. (1979) i n the S t r a i t o f Georgia and i n sediment t r a p data i n Saanich I n l e t by Sancetta and Calvert (1987 i n p r e s s ) . However, S. costatum d i d not always show a c l e a r P L A T E V A n e x a m p l e o f a d i s t i n c t b l o o m o f S . c o s t a t u m . P L A T E VII A character ist ic assemblage within a light lamina bloom a t the edge of a dark, l a y e r . P l a t e VI shows such a j u n c t i o n between a dark l a y e r on the r i g h t with S.costatum i n the c e n t e r / l e f t together with some T h a l a s s i o s i r a S P . I f t h i s can be taken as the s p r i n g bloom, then there i s c l e a r l y some v a r i a t i o n i n i t s i n t e n s i t y when compared with P l a t e IV. P l a t e VII i s an example of a l i g h t l a y e r . I t i s c h a r a c t e r i s e d by a mixture o f l a r g e r S.costatum, numerous Chaetoceros s p e c i e s and t h e i r spores (the b l a c k f e a t u r e s i n t h i s p i c t u r e ) and T h a l a s s i o s i r a . J u n c t i o n s between a l i g h t l a y e r and the dark l a y e r f o l l o w i n g i t appeared to be c h a r a c t e r i s e d by a l a r g e number of Chaetoceros spores, as seen i n P l a t e V I I I . T h i s i s ex-pected s i n c e the s u c c e s s i o n through the summer bloom i n Saanich I n l e t i s such t h a t Chaetoceros becomes dominant l a t e r i n the summer (Takahashi et al. 1977). The c o l l a p s e of t h i s p o p u l a t i o n would be accompanied by the p r o d u c t i o n of a l a r g e number of spores. Blooms o f the s i l i c o f l a g e l l a t e Distephanus specu- lum were o c c a s i o n a l l y seen a t the j u n c t i o n of a l i g h t and the dark l a y e r , as shown i n P l a t e XI. Since t h i s i s thought to be a cool-water s p e c i e s (Polechau, 1974), such blooms might i n d i c a t e the s t a r t o f winter. P L A T E IX A b loom of the s i l i c o f l a g e l a t e D . s p e c u l u m . S C A L E 0 . 1 m m 124 Table X Results of Diatoi counts. Swal* yt.(tg) Area Tot.cells Cells/g COUNTS counted counted I Z II Z III Z IV Z V Z 86 364 24.6 415 8.11E+05 66 15.9 172 41.4 87 21.0 58 14.0 6 1.45 83 122 8.2 495 8.66E+06 56 11.3 287 58.0 63 12.7 72 14.5 4 0.81 84 88 32.8 405 2.45E+06 65 16.0 174 43.0 93 23.0 57 14.1 3 0.74 83 99 24.6 460 3.30€+06 100 21.7 189 41.1 80 17.4 81 17.6 15 3.26 82 270 16.4 467 1.B5E+06 46 9.9 159 34.0 138 29.6 85 18.2 13 2.78 81 117 24.6 434 2.64E+06 82 18.9 103 23.7 150 34.6 76 17.5 8 1.84 80 109 16.4 659 6.45E+06 54 8.2 199 30.2 278 42.2 83 12.6 19 2.88 79 106 16.4 587 5.91E+06 58 9.9 253 43.1 164 27.9 74 12.6 11 1.87 78 95 16.4 481 5.40E+06 62 12.9 207 43.0 88 18.3 79 16.4 11 2.29 77 157 16.4 425 2.89Er06 37 8.7 162 38.1 63 14.8 93 21.9 35 8.24 76 116 16.4 551 5.07Et06 28 5.1 311 56.4 74 13.4 115 20.9 10 1.81 75 158 24.6 405 1.82Er06 58 14.3 192 47.4 51 12.6 82 20.2 12 2.96 74 112 8.2 409 7.79E+06 11 2.7 233 57.0 40 9.8 77 18.8 6 1.47 73 136 16.4 610 4.79E+06 37 6.1 324 53.1 65 10.7 143 23.4 26 4.26 72 94 8.2 404 9.17E+06 26 6.4 228 S6.4 46 11.4 84 20.8 7 1.73 71 118 24.6 422 2.54E+06 46 10.9 188 44.5 55 13.0 78 18.5 20 4.74 70 109 8.2 522 1.02E+07 41 7.9 307 58.8 57 10.9 92 17.6 5 0.96 69 147 8.2 410 5.95Er06 52 12.7 206 50.2 104 25.4 23 5.6 10 2.44 68 134 8.2 400 6.37E+06 35 8.8 95 23.8 133 33.3 129 32.3 1 0.25 67 78 16.4 429 5.87E+06 46 10.7 138 32.2 137 31.9 84 19.6 9 2.10 66 103 32.8 447 2.31E+06 16 3.6 145 32.4 97 21.7 158 35.3 4 0.89 65 110 24.6 446 2.88E+06 48 10.8 94 21.1 no 24.7 174 39.0 9 2.02 64 94 8.2 727 1.65E*07 19 2.6 346 47.6 61 8.4 289 39.8 2 0.28 63 87 32.8 412 2.53E+06 159 38.6 64 15.5 97 23.5 53 12.9 15 3.64 62 98 32.8 411 2.24E+06 103 25.1 56 13.6 63 15.3 164 39.9 7 1.70 61 116 24.6 553 3.39E*06 61 11.0 160 28.9 116 21.0 182 32.9 4 0.72 60 70 16.4 493 7.51E+06 58 11.8 94 19.1 95 19.3 208 42.2 4 0.81 59 119 24.6 529 3.16E+06 95 18.0 115 21.7 81 15.3 196 37.1 2 0.38 58 104 16.4 459 4.71E+06 18 3.9 56 12.2 47 10.2 328 71.5 2 0.44 57 118 8.2 420 7.59ET06 36 8.6 244 58.1 49 11.7 66 15.7 0 0.00 56 193 8.2 995 1.10E+07 32 3.2 666 66.9 20 2.0 251 25.2 3 0.30 55 166 8.2 457 5.87Er06 68 14.9 257 56.2 60 13.1 47 10.3 4 0.88 54 166 8.2 852 1.10E+07 27 3.2 488 57.3 151 17.7 179 21.0 0 0.00 53 137 16.4 402 3.13Et06 59 14.7 131 32.6 76 18.9 115 28.6 5 1.24 52 141 16.4 412 3.12E+06 109 26.5 33 8.0 48 11.7 206 50.0 5 1.21 51 167 24.6 437 1.86Et06 140 32.0 78 17.8 61 14.0 112 25.6 20 4.58 50 114 8.2 414 7.75E+06 20 4.8 309 74.6 10 2.4 67 16.2 2 0.48 t Area counted in u 2 . t Cells/g. calculated using saaple vt. dilution to 13.5il . and aliquots of 250ul. t Cells/ct2/6aonths calculated froa sediientation rate of 45ag/»2/yr. Assuies each layer i s 6 Mnths deposition I Counts show the nuiber of cells counted in each group together vith the Z they represent of the total count COUNTED 6R0UPS: I-Benthics and Pennates. I I- Skeletonena costatu*. I I I s Thalassiosira spp. lV=Chaetoceros spp. V s Silicoflagellates. (D.specului) 125 3.6.2 Diatom counting. The geochemical data i n d i c a t e s t h a t there are p o s s i b l y two types of sediment; an upper type i n which seasonal s i g n a l s appear to be l o s t or on a very f i n e - s c a l e , and a s e c t i o n with a higher sedimentation r a t e i n the lower h a l f of the core i n which varves appear to be preserved. In t h i s s e c t i o n , many elements show c l e a r v a r i a t i o n s between the l i g h t and dark samples. These o b s e r v a t i o n s imply t h a t the laminae below sample 75 are t r u e varves, where v a r i a t i o n i n the l i t h o g e n o u s input to the I n l e t i s preserved and where v a r i a t i o n s i n the diatom assemblages may a l s o be recorded. T h i s c o n c l u s i o n means t h a t the d i s c r e p e n c y between varve counts and the 2 1 ° P b data i s the r e s u l t of v a r i a t i o n i n the s e d i m e n t a t i o n r a t e and the mineralogy a t t h i s s i t e . In order to c o r r o b o r a t e the geochemical o b s e r v a -t i o n s , diatom groups t h a t show seasonal s i g n a l s i n sediment t r a p s moored i n Saanich I n l e t (Sancetta and Calvert, 1987 i n press) were counted. Table X i s a summary of the r e s u l t s o b t a i n e d . F i g . 3.6.1 shows the t o t a l numbers of diatom c e l l s per gram of wet sediment. C e l l counts, with the e x c e p t i o n of the c o r e - t o p above sample 80 and samples 62-63 and 66-67, are higher i n the l i g h t l a y e r s , which i s c o n s i s t e n t with the p r e s e r v a t i o n of a s i g n a l r e f l e c t i n g the known summer maximum of p r o d u c t i o n i n Saanich I n l e t . T h i s seasonal s i g n a l seems to c o n t i n u e above sample 70, which i s the p o i n t a t which 126 127 geochemical data i n d i c a t e a change i n sediment type. I t breaks down onl y i n the samples which c o n t a i n the high carbonate val u e s thought to be a s s o c i a t e d with the dust-dump from Bamberton. V a r i a t i o n i n the p r e s e r v a t i o n o f diatom f r u s t u l e s d u r i n g t h e i r passage through the water column to the s e d i -ments i s the s u b j e c t o f g r e a t u n c e r t a i n t y and debate (Sancetta and Calvert, 1987 i n p r e s s ) . G r a z i n g , i n t e r s p e -c i f i c c o m p e t i t i o n f o r n u t r i e n t s , i l l u m i n a t i o n and temperature are a l l v a r i a b l e s which w i l l a f f e c t the p r e s e r v a t i o n o f diatoms e i t h e r d i r e c t l y , such as g r a z i n g , or i n d i r e c t l y through c o m p e t i t i o n f o r n u t r i e n t s r e s u l t i n g i n v a r i a t i o n s o f the t h i c k n e s s o f f r u s t u l e w a l l s and thus o f t h e i r a b i l i t y to withstand sedimentation processes. Many o f the comparisons made i n t h i s s e c t i o n are based on the assumption t h a t p r e s e r v a t i o n i s consta n t , as there appears to be no s i g n i f i c a n t change i n the s p e c i e s composition between s u r f a c e and bottom water sediment t r a p s near the s i t e o f core CPIV (Sancetta pers comm). However, p r e s e r v a t i o n problems are not ignored. For example, i n t e r s p e c i f i c v a r i a t i o n i n the f r u s t u l e t h i c k n e s s e s w i t h i n the groups counted, without the a d d i t i o n a l d i f f e r e n c e s caused by f a c t o r s such as n u t r i e n t s , temperature and g r a z i n g which show temporal v a r i a t i o n , must be c o n s i d e r e d . S.costatum i s a s m a l l , o f t e n weakly s i l i c i f i e d diatom. The Chaetoceros group c o n t a i n s s p e c i e s which are much more h e a v i l y s i l i c i f i e d , although the Fig: 3.6.2 Relative Abundance of Diatom Groups. Core CPIV. Finlayson Arm. • • Bent H i S.co E M Thai BSftfl Cha S a m p l e N u m b e r 0 10 20 30 40 50 60 70 80 90 100 P e r c e n t of To ta l C o u n t 129 dominant s p e c i e s found i n t h i s study, C.radicans and C.didvmus are small and t h i n walled. The c e n t r i c diatoms i n the T h a l a s s i o s i r a group g e n e r a l l y have t h i c k f r u s t u l e s . Although the appearance of the sediments when s t u d i e d under the microscope i n d i c a t e d t h a t p r e s e r v a t i o n was good, these p o i n t s cannot be ignored i n these types of comparisons. F i g u r e 3.6.2 shows the r e l a t i v e abundances o f the groups counted. I t can be seen t h a t the l a r g e s t v a r i a t i o n s occur a t the base of the core s e c t i o n . A l l four groups show changes i n abundance t h a t are on a longer t i m e s c a l e , assuming the laminae are varves, than would be expected from a seasonal s i g n a l . Above sample 70, the changes i n r e l a t i v e abundance become l e s s obvious, although v a r i a t i o n i n the abundance of b e n t h i c s p e c i e s i s l e s s marked above sample 65. A t r a n s i t i o n a t t h i s p o i n t i s i n keeping with geochemical o b s e r v a t i o n s and with the laminae becoming harder to f o l l o w d u r i n g sampling. I t i s expected t h a t the b e n t h i c s p e c i e s would be i n d i c a t i v e o f turbulance and r e s u s p e n s i o n of sediments w i t h i n the I n l e t s i n c e they are not l i k e l y to be indigenous to the anoxic sediments of the c e n t r a l b a s i n . The count o f b e n t h i c s p e c i e s , which i n c l u d e s P a r a l i a s u l c a t a , and s p e c i e s of N a v i c u l a . N i t z s c h i a . Cocconeis and Grammatophora. i s shown i n F i g . 3.6.3. The v a r i a t i o n between samples i s seen to be random. No c o n s i s t e n t r e l a t i o n s h i p i s obvious between counts o f b e n t h i c s p e c i e s and the l i g h t or dark nature of the l a y e r s , although where a seasonal s i g n a l i s seen, as f o r 130 Fig: 3.6.3 BENTHIC GROUP CELLS/GRAM WET SEDIMENT. K y o 2 3 Z u -i CL 85 -80 -75 -70 -65 -60 -55 50 _ DARK SAMPLE | | LIGHT SAMPLE - S T 1 r— 0.4 0.6 (Millions) CELLS/GRAM Q Ul -I D. Fig: 3.6.4 PLANKTONIC DIATOM COUNTS. Col la/gram. Wet aediment. K a 3 Z 85 -80 -76 -70 -65 -60 66 -60 ^ DARK SAMPLE |"~[ LIGHT SAMPLE 8 10 (Millions) cdttytprom -T— 12 - T -14 16 - - 0 _ 2 - 4 - 6 - 8 - 10 - 1 2 - 1 4 - 1 6 - 18 - 20 " 2 2 - 2 4 -26 - 2 8 - 3 0 example between samples 54-59, the dark l a y e r s do c o n t a i n higher c e l l numbers. An estimate of the c o n t r i b u t i o n o f p l a n k t o n i c s p e c i e s , r e p r e s e n t e d by the other three groups counted, was made by s u b t r a c t i n g the b e n t h i c count from the t o t a l count. The r e s u l t i s shown i n F i g . 3.6.4. As expected, these s p e c i e s g e n e r a l l y have higher counts i n the l i g h t l a y e r s , i mplying t h a t these samples are indeed c o i n c i d e n t with summer d e p o s i t i o n . Counts of Chaetoceros are presented i n F i g . 3.6.5. This group shows the c l e a r e s t seasonal s i g n a l of any group counted. With only two e x c e p t i o n s , samples 62 and 66, the l i g h t l a y e r s show higher counts up to number 80, where the seasonal s i g n a l breaks down. This p r o f i l e , while i t c o r r o b o r a t e s the presence of varves i n the bottom h a l f of the c o r e , does not suggest t h a t a seasonal s i g n a l i s absent i n the upper s e c t i o n . Although intersample v a r i a t i o n s are seen to decrease above sample 75, two e x p l a n a t i o n s f o r the continued seasonal s i g n a l , i n l i g h t of the measured 2 1 ° P b a c t i v i t y (see s e c t i o n 3.1.2), are p o s s i b l e . F i r s t l y , the seasonal counts might simply be chance and t h a t the v a r i a t i o n s seen i n the c o r e - t o p sediment type are i n s i g n i f i c a n t when the e r r o r i n v o l v e d i n the c a l c u l a t i o n o f c e l l s / g i s c o n s i d e r e d . The second e x p l a n a t i o n i s t h a t the top l a y e r of sediment does c o n t a i n a seasonal s i g n a l , t h a t the laminae are f i n e r because of the decreased sedimenta-t i o n r a t e , and t h a t i t was not p o s s i b l e to sample them 1 U i . Fig: 3.6,5 CHAETOCEROS CELLS/GRAM WET SEDIMENT. Z 3 (MDIbna) CELLS/GRAM Fig: 3.6.6 SKELETONEMA COSTATUM CELLS/GRAM WET SEDIMENT. 0 2 4 6 8 (Million*) CELLS/GRAM d i s c r e t e l y because of t h e i r f i n e - s c a l e . Perhaps those samples w i t h i n the t r a n s i t i o n zone which are d i s t i n c t are indeed varves and r e p r e s e n t p e r i o d s of p a r t i c u l a r l y high p r o d u c t i o n , producing a more d i s t i n c t l a y e r to be d e p o s i t e d . Within the c l e a r l y d e f i n e d laminae, Chaetoceros counts are higher i n the l i g h t l a y e r s . T h i s i s expected s i n c e these diatoms are c h a r a c t e r i s t i c o f summer p r o d u c t i o n i n the Saanich I n l e t (Takahashi et al. 1977). Sample 64 stands out i n t h i s p r o f i l e as having very high counts, although i t does not c o n t a i n any unusual chemical s i g n a l . Skeletonema costatum was counted as a s i n g l e s p e c i e s s i n c e i t i s e a s i l y r e c o g n i s e d and i s a c h a r a c t e r i s -t i c s p e c i e s o f the s p r i n g bloom i n the I n l e t (Sancetta and Calvert 1987). I t i s one of the most widespread n e r i t i c s p e c i e s i n the p l a n k t o n o f the e a s t e r n P a c i f i c and i s p a r -t i c u l a r l y common i n the s p r i n g bloom (Cupp, 1943). I t s widespread occurrence i n d i c a t e s t h a t t h i s s p e c i e s has broad environmental t o l e r e n c e s . However, Stockner et al. (1979) have shown t h a t marked annual v a r i a t i o n s i n the abundance of t h i s s p e c i e s are observed i n the S t r a i t o f Georgia. The data on t h i s s p e c i e s i s presented i n F i g . 3.6.6. Counts are seen to be higher i n the l i g h t l a y e r s ; however, a c l e a r and c o n s i s t e n t seasonal s i g n a l i s not e v i d e n t . T h i s supports the i d e a , presented i n s e c t i o n 3.6.1 t h a t S.costatum numbers appear to vary q u i t e c o n s i d e r a b l y between c o n s e c u t i v e years. The abundance of T h a l a s s i o s i r a s p e c i e s shows no c l e a r d i s t i n c t i o n between l i g h t and dark l a y e r s (Fig.3.6.7). 134 Fig: 3.6.7 THALASSIOSIRA CELLS/GRAM WET SEDIMENT. (Million.) CELLS/GRAM T h i s might be expected, s i n c e t h i s group i s thought to be a s s o c i a t e d with the c o o l e r c o n d i t i o n s of e a r l y s p r i n g and l a t e autumn (Takahashi et al. 1977; Sancetta and Calvert, 1987 i n p r e s s ) . I f t h i s i s the case, then they may w e l l become i n c o r p o r a t e d i n dark, samples d u r i n g sampling s i n c e they would occur c l o s e to the j u n c t i o n between l i g h t and dark l a y e r s . T h i s might l e a d to the samples showing a random v a r i a t i o n . In summary, the diatom data lends support to the p r o p o s i t i o n t h a t there are varves preserved i n the bottom h a l f of the core. T h i s i s p a r t i c u l a r l y c l e a r i n the counts o f Chaetoceros. This o b s e r v a t i o n i s taken to mean th a t t h i s group i s e i t h e r l e s s s u c c e p t i b l e to environmental v a r i a t i o n and t h e r f o r e b e t t e r able to s u r v i v e i n v a r i o u s environmental c o n d i t i o n s , or t h a t they are l e s s a f f e c t e d by processes i n the water column, such as g r a z i n g . Chaetoceros counts have a d i s t i n c t and c o n s i s t e n t l i g h t / d a r k up to sample 80, and t h i s r e v e a l s t h a t the upper sediment type c o n t a i n s seasonal s i g n a l s , a l b e i t reduced, and t h a t the d i s c r e p a n c y between the 2 1 ° P b data and the varve counts i s because of d i l u t i o n of the a i o P b a c t i v i t y . CHAPTER 4 DISCUSSION This study has c o n c e n t r a t e d on the upper 32.5 cm of a core c o l l e c t e d i n F i n l a y s o n Arm, Saanich I n l e t . The core has been found to c o n t a i n two types of sediment. The upper 15cm of the s e c t i o n c o n t a i n s a sediment with i n d i s t i c t laminae and a d i s t i n c t geochemistry, while the bottom h a l f of the core c o n t a i n s sediments i n which seasonal s i g n a l s are preserved as varves. The a i o P b data and the p o r o s i t y d e r i v e d from c h l o r i n e c o n c e n t r a t i o n s i n d i c a t e t h a t these two sediments were d e p o s i t e d a t d i f f e r e n t sedimentation r a t e s . Major element geochemistry i n d i c a t e s t h a t the two sediments are c h e m i c a l l y d i s t i n c t . The upper type c o n t a i n s higher c o n c e n t r a t i o n s o f Fe, T i and lower amounts of S i and Mg. Potassium shows no c l e a r d i f f e r e n c e between the sediment types. W i t h i n the varved s e c t i o n , the major elements show some i n d i c a t i o n of seasonal v a r i a t i o n ; however, no c o n s i s t e n t p a t t e r n f o r any element has emerged. The minor elements show l e s s c l e a r d i s t i n c t i o n s between the two sediment types; however, a number of these elements do show a c o n s i s t e n t seasonal s i g n a l w i t h i n the varved s e c t i o n . Vanadium and Sr are p a r t i c u l a r l y good examples, while a number o f other elements show s h o r t e r sequences of l i g h t / d a r k v a r i a t i o n . Barium decreases a t the top and bottom of the core and i s a t a maximum where the opal content o f these sediments i s h i g h e s t . T h i s appears to i n d i c a t e t h a t there has been a change i n primary p r o d u c t i o n 137 w i t h i n F i n l a y s o n Arm and the decrease a t the top and bottom o f the s e c t i o n i m p l i e s a a p r o d u c t i o n change i n a c y c l i c a l f a s h i o n . A n a l y s i s of the diatom assemblages g e n e r a l l y do not show c l e a r seasonal s i g n a l s . The e x c e p t i o n to t h i s i s the c e l l counts of the Chaetoceros group, which does show a c l e a r and c o n s i s t e n t seasonal v a r i a t i o n t h a t c o n t i n u e s out of the varved s e c t i o n and i n t o the upper sediment type. T o t a l Chaetoceros counts a l s o decrease where other evidence suggests t h a t primary p r o d u c t i o n decreases. The a c t i v i t y o f a i o P b does not appear to show any s i g n s of d i s r u p t i o n caused by mixing; however, i t has been shown t h a t the change i n sedimentation r a t e has d i s t o r t e d the a c t i v i t y p r o f i l e of t h i s i s o t o p e making i t impossible to d e r i v e a chronology f o r t h i s c o re. Despite the l a c k of a w e l l d e f i n e d chronology, t h i s study has i d e n t i f i e d d i s t i n c t changes i n the sediment r e c o r d which may be a t t r i b u t e d to oceanographic and s e d i m e n t a t i o n changes. A number of c o n c l u s i o n s can be d e r i v e d from t h i s study which w i l l prove u s e f u l to any such r e s e a r c h contemplated i n the f u t u r e . Many o f these c o n c l u s i o n s are best presented i n a review of the sediment h i s t o r y r e v e a l e d by core CPIV. I t i s proposed t h a t the true sediment/water i n t e r f a c e has been l o s t and t h a t the s u r f a c e o f the core i n f a c t r e p r e s e n t s sediments approximately 20 years o l d . T h i s o b s e r v a t i o n i s supported by lower 2 1 ° P b a c t i v i t i e s i n the s u r f a c e sediments 138 than those found i n other s t u d i e s i n Saanich I n l e t (although Carpenter and Beasley (1981) do show low values i n F i n l a y s o n Arm which they a l s o a t t r i b u t e to sediment l o s s ) . I t i s a l s o supported by high 1 3 r C s a c t i v i t y i n the top few samples of the core which, although the p r o f i l e of 1 3 T C s i s not w e l l d e f i n e d , i n d i c a t e t h a t these h o r i z o n s are pre-1963 s i n c e higher v a l u e s c l o s e to the expected maximum of around 400 dpm/kg are not seen i n samples from lower i n the core. The peak i n carbonate w i t h i n the top few samples i s thought to be a s s o c i a t e d with a dump of limestone dust which o c c u r r e d between 1960-1963. This i s u n l i k e l y to be r e c e n t b i o g e n i c carbonate because the Sr p r o f i l e does not show a s i m i l a r i n c r e a s e . The l o s s o f sediments from the c o r e - t o p i s probably due to the very high water content of s u r f a c e sediments i n the c e n t r a l b a s i n of Saanich I n l e t . The measured a c t i v i t y of 2 1 ° P b r e v e a l e d a l a r g e d i s c r e p a n c y between varve counts (the s e c t i o n s t u d i e d c o n t a i n s 36 sampled laminae r e p r e s e n t i n g 18 years of summer/winter d e p o s i t i o n ) and the a s s i g n e d ages based on the 22.2 y r s h a l f - l i f e o f 2 t o P b . The measured s u r f a c e a c t i v i t y o f lOdpm/g decreases to l.ldpm/g a t 32.5cm depth, implying t h a t the s e c t i o n c o n t a i n s sediments d e p o s i t e d over approximately three h a l f - l i v e s , or 65-70 years. T h i s mismatch means t h a t the o r i g i n a l goal of the study c o u l d not be a t t a i n e d . Geochemical data on the major and minor element c o n c e n t r a t i o n s i n the samples r e v e a l e d t h a t there appeared 139 to be a change i n mineralogy and perhaps a change i n the p r o p o r t i o n o f marine vs t e r r e s t r i a l m a t e r i a l , r e f l e c t e d i n a decrease i n p r o d u c t i o n w i t h i n the top 10-15cm of the core. The boundary between sediment types i s not w e l l d e f i n e d , but i s thought to l i e between samples 70-80. The sediment type i n the upper core i s not d i s t i n g u i s h e d by the XRD s p e c t r a , and t h i s i m p l i e s t h a t the a d d i t i o n a l m a t e r i a l i s an amorphous or p o o r l y c r y s t a l l i n e phase. P o s s i b l e candidates i n c l u d e d e t r i t u s from the Bamberton p l a n t and an i n c r e a s e d i n p u t o f s o i l c l a y s ; however, a b e t t e r d e f i n i t i o n o f t h i s mineral phase i s not p o s s i b l e . On the b a s i s o f the geochemical evidence, supported by the o b s e r v a t i o n t h a t l i g h t / d a r k v a r i a t i o n i n water contents were preserved, the c h l o r i n e p r o f i l e i s a tru e i n d i c a t i o n o f the p o r o s i t y o f the samples. When p o r o s i t y was c a l c u l a t e d from the water co n t e n t s , there was seen to be lower p o r o s i t y a t the top of the core r i s i n g to a maximum i n sample 68 and then d e c r e a s i n g a g a i n to sample 50. The diatom data do c l e a r l y support the boundary between the two sediment types being p l a c e d a t sample 70. While most of the groups counted do not show a c o n s i s t e n t v a r i a t i o n between l i g h t and dark samples, counts o f Chaetoceros do appear to i n d i c a t e a c l e a r and c o n s i s t e n t seasonal s i g n a l showing higher counts i n the l i g h t (summer) laminae. T h i s s i g n a l , although the d i f f e r e n c e i n counts between adjacent laminae are reduced above sample 70, n e v e r t h e l e s s c o n t i n u e s to show l i g h t / d a r k v a r i a t i o n up to 140 sample 80. T h i s i s almost c o i n c i d e n t with the i n c r e a s e i n carbonate t h a t s t a r t s i n sample 78. T h i s o b s e r v a t i o n i s i n c o n s i s t e n t with the measured decrease i n 2 1 ° P b a c t i v i t y . Excess 2 1 ° P b decreases from lOdpm/g i n sample 86 and 12dpm/g i n sample 85 to 3.8dpm/g i n sample 75 (thought to be c o a r s e r - g r a i n e d and shown to c o n t a i n higher amounts of l i t h o g e n o u s elements such as F e , T i and Mg) and 1.7dpm/g i n sample 70. There i s a s m a l l e r change from here to the base o f the s e c t i o n , from 1.7dpm/g to l.ldpm/g. By f a r the g r e a t e s t decrease i n a i o P b a c t i v i t y o c curs above sample 70. I n t e r p r e t a t i o n o f the a*°Pb data, u s i n g a steady-s t a t e s e d i m e n t a t i o n model i m p l i e s t h a t the core s e c t i o n covers a time p e r i o d o f 65-70 years. However, the o b s e r v a t i o n of a m i n e r a l o g i c a l l y d i f f e r e n t sediment i n the top h a l f of the core throws doubt on t h i s chronology and suggests t h a t the s e d i m e n t a t i o n r a t e has a l s o changed and t h a t , g i v e n a change i n mineralogy, the r e l a t i v e p r o p o r t i o n s of a*°Pb-depleted t e r r e s t r i a l m a t e r i a l to 2 1°Pb-rich marine d e t r i t u s might a l s o have changed. Although the observed p o r o s i t i e s based on the c h l o r i n e data and the non s t e a d y - s t a t e s e d i m e n t a t i o n i m p l i e d by the geochemistry meant t h a t good estimates of s e d i m e n t a t i o n r a t e based on 2 1 ° P b decay c o u l d not be c a l c u l a t e d , a c a l c u l a t i o n was performed u s i n g the observed p o r o s i t i e s . T h i s i n d i c a t e d t h a t the upper sediment type had a s e d i m e n t a t i o n r a t e of 0.31 cm/year while the lower h a l f of 141 the s e c t i o n , below sample 70, had a r a t e of 1.03 cm/year. While these r e s u l t s are somewhat q u e s t i o n a b l e , they do i n d i c a t e t h a t s edimentation r a t e s i n the top 15cm of the core were s u b s t a n t i a l l y lower than i n the lower h a l f . I f there has been a change i n sediment type and i n the p r o p o r t i o n s of t e r r e s t r i a l and marine sediment components together with a change i n se d i m e n t a t i o n r a t e , the 2 1 ° P b a c t i v i t y decrease measured i n t h i s s e c t i o n i s not a r e f l e c t i o n of r a d i o a c t i v e decay. The sediment i n the upper core i s not the product of a sudden input of t e r r e s t r i a l or nearshore sediment because t h i s would be r e f l e c t e d i n an anomalously low 2 1 ° P b a c t i v i t y . Moreover, f e a t u r e s such as the peak i n carbonate, Mn and Pb would not l i k e l y be preserved i n such a r a p i d d e p o s i t i o n a l event. In c o n t r a s t to the a i o P b data, the carbonate peak probably c o i n c i d e s with a dump of carbonate dust from Bamberton which took p l a c e between 1960-1963. A c l e a r d e f i n i t i o n of t h i s would r e q u i r e a much more d e t a i l e d 1 3 7 € s p r o f i l e . A change i n the primary p r o d u c t i o n d u r i n g t h i s p e r i o d might a l s o have an e f f e c t on the f l u x of 2 1 ° P b i n t o the sediments. Robbins (1978) s t a t e d t h a t v a r i a t i o n s of primary p r o d u c t i o n are a major i n f l u e n c e on the r e l a t i o n s h i p between a i o P b d e l i v e r y and the measured a c t i v i t y i n s u r f a c e waters and thus, presumably, a t the sediment i n t e r f a c e . Although c o a s t a l waters are g e n e r a l l y thought to be p a r t i c l e - r i c h and thus p r o v i d e a ready source of v e c t o r s to t r a n s p o r t a i o P b to the sediments, i t may be t h a t the q u i e t c o n d i t i o n s i n F i n l a y s o n Arm do allow l a r g e v a r i a t i o n i n the p a r t i c u l a t e l o a d of the water column to occur. One problem with t h i s e x p l a n a t i o n i s the i n c r e a s i n g contents of o r g a n i c carbon i n the s u r f a c e sediment. Carbon, without the opal c o r r e c t i o n , i s seen to i n c r e a s e from sample 70 upwards, c o i n c i d e n t with the decrease i n Ba and S i and lower Chaetoceros counts t h a t are thought to i n d i c a t e decreased p r o d u c t i o n . However, i f the decrease i n sedimentation r a t e was more s i g n i f i c a n t than the d i l u t i o n of carbon by the t e r r e s t r i a l m a t e r i a l , then an i n c r e a s e d carbon content might be expected. Below t h i s change i n sedimentation, the laminae appear to be varves. Vanadium, Sr, and counts of Chaetoceros show c o n s i s t e n t light/dark, v a r i a t i o n s which are i n d i c a t i v e of seasonal i n p u t . Many of the other major and minor elements do not show c o n s i s t e n t v a r i a t i o n s , but there are s e c t i o n s of some p r o f i l e s where c l e a r l i g h t / d a r k , v a r i a t i o n s are observed which conform to p u l s e s of l i t h o g e n o u s i n p u t to the I n l e t . These v a r i a t i o n s are c o n s i s t e n t with those proposed by Gross and Gucluer (1964) to account f o r the varves i n Saanich I n l e t . They suggested t h a t the l i g h t l a y e r s r e p r e s e n t summer p r o d u c t i o n , and indeed the Chaetoceros counts are a l l higher i n the l i g h t l a y e r s i n t h i s c o re. They a l s o suggested t h a t the dark l a y e r s c o n t a i n higher amounts of l i t h o g e n o u s m a t e r i a l and t h i s too i s c o n s i s t e n t with the o b s e r v a t i o n s i n t h i s core. I t i s i n t e r e s t i n g to note, however, t h a t Gross and Gucluer (1964) d i s t i n g u i s h the laminae they sampled p a r t l y on the b a s i s o f counts o f P a r a l i a s u l c a t a , a b e n t h i c diatom, and counts o f S.costatum. both o f which do not show any c l e a r d i s t i n c t i o n i n t h i s c o re. The reason t h a t these two diatoms do not show a seasonal s i g n a l i n t h i s c ore, but t h a t Chaetoceros does, i s thought to be l i n k e d to g r a z i n g . I t i s p o s s i b l e t h a t the major f a c t o r a f f e c t i n g the diatom remains r e a c h i n g the sediments i n F i n l a y s o n Arm i s the extent to which they are grazed by zooplankton. Stockner and Cliff (1979) s t a t e t h a t g r a z i n g i s the prime c o n t r o l on phytoplankton p o p u l a t i o n s i n the S t r a i t o f Georgia. Chaetoceros s p e c i e s are c h a r a c t e r i s e d by l o n g , o f t e n s piny chaetae and i t i s c o n c e i v a b l e t h a t these w i l l a f f o r d the c e l l s some degree o f p r o t e c t i o n from g r a z i n g . In order to develop a chronology f o r the core s e c t i o n s t u d i e d , i t would be necessary to a s s i g n a f i x e d date to a p o i n t and to d e r i v e the chronology by varve c o u n t i n g . T h i s i s complicated by the a p p a r e n t l y gradual change i n sediment type and the u n c e r t a i n t y as to how many years the change r e p r e s e n t s . The onl y p o i n t f o r which there i s some good evidence a v a i l a b l e which would allow i t to be f i x e d i n time i s the carbonate dump from the Bamberton P l a n t . I f the base of the carbonate peak, a t sample 78, i s taken to r e p r e s e n t 1960, then the 2 l o P b a c t i v i t y i s seen to decrease from around 4.0dpm/g to l.ldpm/g i n sample 50. This r e p r e s e n t s two h a l f - l i v e s o f decay (approximately 45 y r s ) compared with only 14 years o f varve r e c o r d . 144 I f , on the other hand, the change i n sedimentation i s taken to occur a t sample 75, and the small v a r i a t i o n s i n the Chaetoceros counts above t h i s are taken to be i n s i g n i f i c a n t and not r e p r e s e n t a t i v e of seasonal sedimentation, then there i s approximately one h a l f - l i f e o f 2 1 ° P b (22.5yrs) between t h i s p o i n t and the base of the core. T h i s s t i l l means t h a t there should be twice the number of varves a c t u a l l y counted (12.5 years between samples 75-50), although the d i f f e r e n c e i s not so d i s c r e p a n t . I f the breakdown of the seasonal s i g n a l i s taken to occur a t sample 70, where the geochemical data i n d i c a t e s a change i n sedimentation, then there i s a decrease i n a i o P b a c t i v i t y equal to a l i t t l e over one h a l f a h a l f - l i f e (around 14 y e a r s ) . T h i s matches reasonably w e l l with 10 years of counted varves. These l a s t two p o s s i b i l i t i e s do not, however, allow a chronology to be adopted f o r the whole s e c t i o n , s i n c e there i s no other time marker w i t h i n the varved s e c t i o n and s i n c e the time r e p r e s e n t e d by the sediments between the onset of the sediment change and the carbonate peak i s unknown. The on l y c o n c l u s i o n p o s s i b l e i s t h a t a t i m e - s c a l e cannot be assi g n e d to the sediment s e c t i o n and we are unable to examine f l o r a l and geochemical changes with r e s p e c t to c l i m a t i c and r u n o f f r e c o r d s f o r the l o c a l a rea. The p o s s i b l e change i n p r o d u c t i o n i s , however i n t e r e s t i n g from a palaeoceanographic viewpoint. Above sample 70, and to a l e s s e r extent w i t h i n the f i v e lowest samples i n the core, Ba contents decreases. Together with the decrease i n S i , t h i s might i n d i c a t e lower p r o d u c t i o n w i t h i n F i n l a y s o n Arm. Large v a r i a t i o n s i n annual p r o d u c t i o n and the success o f the common s p e c i e s of diatoms have been shown to occur i n the S t r a i t of Georgia {Stockner et al. 1979). I f such v a r i a t i o n i s p o s s i b l e w i t h i n the p h y s i c a l l y mixed environment which the S t r a i t r e p r e s e n t s , then i t might be expected t h a t i n Saanich I n l e t , and e s p e c i a l l y F i n l a y s o n Arm where the mixing processes are thought to be much weaker, l a r g e v a r i a t i o n s i n primary p r o d u c t i o n might a l s o occur. Although t h i s might e x p l a i n between-layer v a r i a t i o n s i n the diatom counts, the change i m p l i e d by the Ba data, and p o s s i b l y by the Chaetoceros data, i n d i c a t e a change i n p r o d u c t i o n on a 10-15 year c y c l e , with the top and bottom of the core being c h a r a c t e r i s e d by lower p r o d u c t i v i t y . T h i s i s a c y c l e d e r i v e d u s i n g the b e s t estimate of a chronology f o r t h i s core and assumes t h a t the l e s s w e l l d e f i n e d change i n se d i m e n t a t i o n a t the bottom of the core a l s o r e p r e s e n t s a change i n p r o d u c t i o n . There does appear to be an i n c r e a s e i n Fe between sample 50-55, and Ba, o r g a n i c carbon and the S i : A l r a t i o a l l i n d i c a t e t h a t there i s a f u r t h e r change i n se d i m e n t a t i o n here. Chaetoceros counts, which have been shown to i n d i c a t e c l e a r seasonal f l u c t u a t i o n s , are h i g h e s t i n the middle of the core and decrease a t the top and bottom. The reason f o r such long-term f l u c t u a t i o n s i n the p r o d u c t i o n i s not known; however, such v a r i a b i l i t y has been 146 r e c o g n i s e d i n other s t u d i e s . Colebrook (1982) has shown seasonal and annual v a r i a t i o n i n the p l a n k t o n of the North A t l a n t i c , sampled with a Hardy plankton r e c o r d e r , although he c o n c e n t r a t e d h i s a n a l y s i s on change due to geographic v a r i a t i o n . Gieskes and Kraay (1977) used r e c o r d s from the same equipment to p r o v i d e a data s e r i e s o f plankton i n the North Sea from 1948-1975. This data s e t c l e a r l y shows l a r g e f l u c t u a t i o n s on both s h o r t (monthly/interannual) and longer (multi-annual) t i m e - s c a l e s i n both phyto- and zooplankton p o p u l a t i o n s . They showed t h a t the long-term f l u c t u a t i o n s are not thought to be the r e s u l t of anthropogenic i n f l u e n c e , but argue t h a t they are caused by v a r i a t i o n i n seawater temperature, f l u c t u a t i o n s i n s o l a r r a d i a t i o n and gradual change i n the atmospheric p a t t e r n s over the North A t l a n t i c , and t h e r e f o r e i n c i r c u l a t i o n . Salmon m i g r a t i o n r o u t e s i n the Northeast P a c i f i c show t h a t they are i n f l u e n c e d by long-term v a r i a b i l i t y i n c l i m a t i c p a t t e r n s (.Hamilton, 1980; Mysak et al., 1986), and t h i s i m p l i e s t h a t there i s reason to b e l i e v e changes i n the atmosphere, and thus i n the oceanographic regime of t h i s r e g i o n , are i n f l u e n c i n g the b i o l o g i c a l oceanography. I t i s t h e r e f o r e reasonable to argue t h a t such i n f l u e n c e s might have a long-term e f f e c t on phytoplankton p o p u l a t i o n s and thus on primary p r o d u c t i o n . A review of v a r i a b i l i t y on both s h o r t and long time s c a l e s and of the i m p l i c a t i o n s of such change on our understanding of p l a n k t o n dynamics, i s p r o v i d e d by Harris 147 (1980), although h i s a n a l y s i s c o n c e n t r a t e s on s h o r t term f l u c t u a t i o n s . V a r i a b i l i t y on t i m e s c a l e s o f years or decades are l i k e l y to become even more s i g n i f i c a n t i n the l i g h t o f c u r r e n t r e s e a r c h aimed a t the study of g l o b a l v a r i a b i l i t y i n c l i m a t i c , oceanographic and geochemical data. 148 CHAPTER 5: SUMMARY AND CONCLUSIONS^  5.1 Summary. Cores o f varved sediments were c o l l e c t e d from F i n -l a y s o n Arm i n Saanich I n l e t . T h i s p a r t o f the I n l e t was cho-sen because i t was thought t h a t cores o f u n d i s t u r b e d s e d i -ments c o u l d be obtained. The i n i t i a l o b j e c t i v e s o f the study c a l l e d f o r the development of a we l l d e f i n e d chronology t h a t would allow the i n t e r p r e t a t i o n o f the geochemical and diatom r e c o r d p reserved i n the sediments. On the c o n d i t i o n t h a t they can be s u c c e s s f u l l y sampled, the varves themselves would p r o v i d e such a chronology; however, the o b j e c t i v e s o f the study c a l l e d f o r c o n f i r m a t i o n o f such a varve chronology with measurements 2 I O P b and the development of a t i m e s c a l e based on the 22.2 h a l f - l i f e o f t h i s i s o t o p e . Samples c o l l e c t e d from the varve laminae o f a core t h a t was thought to have a preserved i n t e r f a c e r e v e a l e d a l a r g e d i s c r e p a n c y between the varve counts and the measured decay of 2 1 ° P b . Varve counts i n d i c a t e d t h a t there were 18 years o f d e p o s i t i o n i n the top 35cm of core CPIV, while the decay of 2 1 ° P b i n d i c a t e d t h a t the same s e c t i o n should c o n t a i n the r e c o r d o f 65-70 years. T h i s r a i s e d the p o s s i b i l i t y t h a t the laminae seen might not be true annual varves, but t h a t they recorded longer c y c l e s o f accumulation. However, m i c r o s c o p i c s t u d i e s 149 of w e l l - p r e s e r v e d laminae from lower i n the same core,and of varves preserved w i t h i n the sampled s e c t i o n , r e v e a l e d t h a t a seasonal s i g n a l c o u l d be determined from the laminae and t h a t they appeared to c l e a r l y r e f l e c t the seasonal s u c e s s i o n of diatoms known to occur i n Saanich I n l e t . Measurement of the * 3 7Cs content of some samples, while f a r from p r o v i d i n g a complete p r o f i l e of the core, d i d , however, tend to support the 2 1 ° P b data i n t h a t higher X37Cs contents were found around the s e c t i o n a t which a i o P b i n d i c a t e d t h a t the sediments were d e p o s i t e d around 1960. The 1 3 T C s val u e s o b t a i n e d from the top of t h i s core are high enough t h a t they must l i e w i t h i n the time zone 1945-1963. Th i s i n f o r m a t i o n f o r c e d the focus of the study to be changed so t h a t t h i s d i s c r e p a n c y c o u l d be i n v e s t i g a t e d i n d e t a i l . A geochemical a n a l y s i s and the d e t e r m i n a t i o n o f diatom assemblages, based on counts of the major diatom groups which show seasonal s i g n a l s i n sediment t r a p s w i t h i n Saanich I n l e t , was c a r r i e d out on samples taken form i n d i v i d u a l laminae w i t h i n the top 32.5cm o f one core. The o b s e r v a t i o n s gathered from t h i s study i n d i c a t e t h a t s e d i m e n t a t i o n w i t h i n F i n l a y s o n Arm i s not steady and t h a t f l u c t u a t i o n s seem to occur i n sedimentation r a t e , bulk mineralogy and primary p r o d u c t i o n . Thus, the r e l a t i v e p r o p o r t i o n s of marine and t e r r e s t r i a l d e t r i t u s are s u b j e c t to change. I t i s proposed t h a t t h i s a f f e c t s the observed 2 1 ° P b p r o f i l e and t h a t t h i s i s the cause of the d i s c r e p a n c y between varve counts and the 2 1 ° P b p r o f i l e i n t h i s core. 150 Two c l e a r l y d e f i n e d sediment types and sedimenta-t i o n regimes were seen i n t h i s s e c t i o n . There a l s o appears to be a change i n sediment w i t h i n the lowest f i v e samples from the base of the s e c t i o n , although t h i s change i s not so w e l l d e f i n e d . The top 15cm of the core c o n t a i n s sediments which are c h a r a c t e r i s e d by lower sedimentation r a t e s and an i n -creased amount of an undefined, p o o r l y c r y s t a l l i n e mineral phase or phases t h a t are probably o f t e r r e s t r i a l o r i g i n . P r eserved w i t h i n t h i s s e c t i o n i s a peak, i n carbonate which has been l i n k e d to a dump of carbonate dust from the cement p r o d u c t i o n p l a n t a t Bamberton between 1960-1963; however, t h i s cannot be used to d e f i n e a chronology because o f the u n c e r t a i n t y i n the time r e p r e s e n t e d by the sediments between the base of the carbonate peak and the c l e a r l y d e f i n e d varves lower i n the core. The upper s e c t i o n of the sediment a l s o appears to c o i n c i d e with decreased primary p r o d u c t i o n and, together with what appears to be another decrease i n p r o d u c t i o n a t the base of the c o r e , might i n d i c a t e t h a t p r i -mary p r o d u c t i v i t y i n t h i s p a r t of Saanich I n l e t , and perhaps i n the I n l e t as a whole, i s s u b j e c t to some unknown i n f l u e n c e which generates long-term c y c l e s . Such a c y c l e would have a p e r i o d i c i t y o f between 10-15 years based on the decay of 2 1 ° P b and i t s best f i t with the varve counts. The o r i g i n a l o b s e r v a t i o n o f a l a r g e d i s c r e p a n c y between the varve counts and the measured 2 1 ° P b a c t i v i t i e s i s e x p l a i n e d by the d i l u t i o n of the i s o t o p e by i n c r e a s e d p r o p o r t i o n s o f 2 1°Pb-depleted t e r r e s t r i a l m a t e r i a l r e l a t i v e to marine d e t r i t u s , and by the proposed change i n p r o d u c t i o n which might r e s u l t i n a decreased f l u x o f a i o P b to the sediments. Both of these p o s s i b i l i t i e s would r e s u l t i n decreased c o n c e n t r a t i o n s of the i s o t o p e and thus the observed decay would not r e f l e c t the true a c t i v i t y decrease but would c o n t a i n a s i g n a l imposed by the nonsteady sedimentation r a t e s and d i l u t i o n . Below the upper anomalous s e c t i o n o f the co r e , annual varves appear to be w e l l preserved. A number of elements show c l e a r i n d i c a t i o n s o f pu l s e d l i t h o g e n o u s i n p u t w i t h i n t h i s s e c t i o n . However, i t seems t h a t the t r a n s i t i o n between the two sediment types i s a gradual one o c c u r r i n g between samples 70 and 80, and because of t h i s i t i s not p o s s i b l e to d e f i n e a chronology f o r the core. Counts o f Chaetoceros show the c l e a r e s t seasonal s i g n a l and, although decreased, t h i s i s seen to continue through the m i n e r a l o g i c a l change. I t may be t h a t a seasonal s i g n a l i s preserved w i t h i n t h i s s e c t i o n on a s c a l e which was too f i n e to be sampled. The lack, o f a chronology means t h a t palaeoceano-g r a p h i c i n t e r p r e t a t i o n s cannot be developed from the data c o n t a i n e d i n t h i s c o re. However a number of u s e f u l c o n c l u -s i o n s can be drawn from t h i s study. 152 5.2 Co n c l u s i o n s . 1: The varves observed w i t h i n the sediments o f Saanich I n l e t do r e f l e c t a seasonal s i g n a l with the l i g h t l a y -e r s c o n t a i n i n g the r e c o r d o f summer p r o d u c t i o n and the dark l a y e r s c o n t a i n i n g i n c r e a s e d amounts of t e r r e s t r i a l m a t e r i a l . T h i s i s c o n s i s t a n t with p r e v i o u s e x p l a n a t i o n s of varve p r o d u c t i o n i n Saanich I n l e t by Gucluer and Gross (1964). 2: Sedimentation i n F i n l a y s o n Arm i s c h a r a c t e r i s e d by v a r i a b l e sedimentation r a t e s and m i n e r a l o g i c a l composi-t i o n . T h i s has d i s t u r b e d the a c t i v i t y p r o f i l e o f 2 1 ° P b . This s i t e i s not c o n s i d e r e d to be s u i t a b l e f o r f u r t h e r palaeoceanographic s t u d i e s . 3: The d i s c r e p a n c y between the number of varves and the a i o P b a c t i v i t y i s e x p l a i n e d by the d i l u t i o n o f the is o t o p e w i t h i n the upper s e c t i o n o f t h i s core and by the non s t e a d y - s t a t e sedimentation. 4: A carbonate dust dump from the Bamberton cement p l a n t between 1960-1963 appears to be u s e f u l as a time marker w i t h i n the I n l e t . At t h i s l o c a l i t y t h i s dump was d e f i n e d by an i n c r e a s e o f around 4 wt% CaCOa. 5: I t appears t h a t the pre-compaction water contents o f the sediments i n the c e n t r a l b a s i n makes the i d e n t i f i c a t i o n of the true sediment/water i n t e r f a c e very d i f f i c u l t . In t h i s core i t appears t h a t some 20-25 years o f s u r f a c e sediment has been l o s t , and t h a t the i n t e r f a c e recovered r e p r e s e n t s sediments d e p o s i t e d i n the e a r l y 1960's. 6: Major element c o n c e n t r a t i o n s i n the i n d i v i d u a l laminae do not show c l e a r and c o n s i s t e n t seasonal s i g n a l s . The c l e a r e s t i n d i c a t i o n o f p u l s e d inputs o f t e r r i g e n o u s m a t e r i a l i s seen i n the a b s o l u t e abundances of some minor elements, e s p e c i a l l y V and Sr. 7: Barium c o n c e n t r a t i o n s appear to be l i n k e d to changes i n the primary p r o d u c t i o n o f the I n l e t and v a r i a t i o n s i n the r a t i o o f t h i s element to A l might i n d i c a t e t h a t there are 10-15 year c y c l e s o f p r o d u c t i o n . D e t a i l e d a n a l y s i s o f Ba, s t e r o l s (to t r y and p i n p o i n t the t r u e nature o f the Ba-production a s s o c i a t i o n ) and w e l l de-f i n e d opal d e t e r m i n a t i o n s on a longer core with a known chronology might p r o v i d e some i n t e r e s t i n g i n f o r m a t i o n on the palaeoceanography of Saanich I n l e t . Long-term data s e t s on phytoplankton, and v a r i a b i l i t y o f t h e i r p o p u l a t i o n s , would be u s e f u l and may be p a r t i c u l a r l y e n l i g h t e n i n g i n view of the c l i m a t i c and oceanographic v a r i a b i l i t y know to a f f e c t t h i s r e g i o n . 8: High Mn c o n c e n t r a t i o n s i n the core top are not thought to i n d i c a t e t h a t the cor e - t o p was o x i c but r a t h e r t h a t t h i s metal i s a s s o c i a t e d as a p o l l u t a n t with the carbonate dump. 154 9: Most groups of diatoms preserved i n the sediments do not appear to show c l e a r seasonal s i g n a l s i n the samples c o l l e c t e d . The e x c e p t i o n to t h i s i s the Chaetoceros group which shows a c l e a r and c o n s i s t e n t seasonal p a t t e r n . The proposed reason f o r t h i s i s t h a t the chateae, which are c h a r a c t e r i s t i c o f t h i s group, a f f o r d them some p r o t e c t i o n from g r a z i n g by zoo-plankton. Because o f t h i s , f u t u r e s t u d i e s should c o n s i d e r t h i s group i n more d e t a i l . 10: The v a r i a t i o n seen i n the other diatom groups counted may r e f l e c t g r a z i n g although there i s evidence t h a t even the major diatom groups undergo l a r g e annual f l u c t u a t i o n s i n t h e i r abundances w i t h i n the S t r a i t o f Georgia and probably, t h e r e f o r e , i n Saanich I n l e t . 11: Future s t u d i e s o f diatom sedimentation i n Saanich I n l e t should be supplemented by s t u d i e s o f f r e s h p l a n k t o n m a t e r i a l i n order to q u a n t i f y the e f f e c t o f g r a z i n g on the thanatocoenoses. BIBLIOGRAPHY Abbey S. 1980. 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PP 283-301. 165 APPENDIX A, Determination of 2 1 ° P b i n Sediments. The method used was taken from Smith and Walton (1980) and i s based on Flynn (1968). Sample p r e p a r a t i o n . Approximately 1 gram of ground sediment was weighed a c c u r a t e l y and p l a c e d i n a c l e a n t e f l o n bomb. The sample was then d i g e s t e d with c o n c e n t r a t e d n i t r i c (6ml) and h y d r o f l u o r i c a c i d s (6ml). I f foaming o c c u r r e d , a few drops of n-octanol was added. The sediment/acid mixture was then s p i k e d with a known amount of 2 0 B P o as a y i e l d t r a c e r . A s o l u t i o n of 2°°Po was prepared by d i l u t i o n from a stock s o l u t i o n with 0.5N HCl to g i v e a working c o n c e n t r a t i o n of 9.32 dpm/ml. when f r e s h . The h a l f l i f e of 2 ° e P o i s 10 35 days; the samples f o r t h i s study were processed before any s i g n i f i c a n t decrease i n a c t i v i t y o c c u r r e d . The s e a l e d t e f l o n bomb was heated i n a water bath at 90°C f o r 6 hours. A f t e r removing excess water from around the j o i n between the l i d and the base with a t i s s u e , the bomb was p a r t i a l l y immersed i n a c o l d water bath and allowed to c o o l o v e r n i g h t . The water l e v e l reached w e l l 166 below the l i d , thereby a v o i d i n g any contamination of the sample. The contents the bomb were t r a n s f e r r e d to a c l e a n t e f l o n beaker u s i n g washes of 0. 5N HCl from a squeeze b o t t l e . A f i n a l r i n s e was performed with around 20ml.of c o n c e n t r a t e d HCl. The beaker was p l a c e d on a hot p l a t e and the contents reduced to near dryness. 20ml of cone. HCl were then added, s w i r l e d and b o i l e d down. This was repeated twice. The r e s i d u e was t r a n s f e r r e d to a pyrex c e n t r i f u g e tube with washes of 0.5N HCl, each wash being w e l l mixed and heated on the hot p l a t e before being poured i n t o the c e n t r i f u g e tube. Four or f i v e washes were used. This s o l u t i o n was c e n t r i f u g e d a t 3000rpm. f o r 20 min. a f t e r which the supernatant was c a r e f u l l y poured i n t o a 150 ml. pyrex beaker. C e n t r i f u g i n g was repeated twice more with enough 0. 5N HCl being added and s w i r l e d to g i v e about 100 ml. as the f i n a l volume o f p l a t i n g s o l u t i o n . The beaker was kept covered u n t i l p l a t i n g . The s o l i d r e s i d u e was t r a n s f e r r e d to p l a s t i c b o t t l e s and s t o r e d . P l a t i n g method. The polonium i n s o l u t i o n was p l a t e d onto n i c k e l d i s c s . These were made from 1.5mm t h i c k BDH Assured sheet n i c k e l . The d i s c s were cut by hand to approximately IK inches and then turned on a l a t h e to e x a c t l y 1 i n c h (2.2 cm) to f i t the ORTEC sample h o l d e r s . The d i s c s were cleaned with methanol and then with d i s t i l l e d water. They were then 167 p l a c e d i n t o t e f l o n h o l d e r s f o l l o w i n g a d e s i g n i n Flynn (1968). These are designed so t h a t the p l a t i n g s o l u t i o n i s prevented by an 0 - r i n g from coming i n t o c o n t a c t with the back of the d i s c . The h o l d e r s form a l i d to the p l a t i n g beaker and h o l d a thermometer and the d i s c which i s suspended i n the s o l u t i o n . 0.2g. of a s c o r b i c a c i d and around 0.5g. of hydroxylammonium c h l o r i d e were added to the p l a t i n g s o l u t i o n to reduce any F e 3 * which causes a s i g n i f i c a n t decrease i n p l a t i n g e f f i c i e n c y (Flynn, 1968). The beaker, c o n t a i n i n g the p l a t i n g s o l u t i o n , a t e f l o n coated s t i r bar and holder was p l a c e d onto a hot p l a t e / s t i r r e r . The s o l u t i o n was maintained at 85 °C f o r 6 h r s . A i r bubbles were removed from the d i s c s u r f a c e by w i g g l i n g the h o l d e r . The minimum s t i r r i n g r a t e was used to a v o i d excess e v a p o r a t i o n . The beaker was then removed from the h o t p l a t e and the d i s c removed. I t was r i n s e d i n methanol and then i n d i s t i l l e d water and allowed to a i r dry. The d i s c s were s t o r e d i n a p e t r i e d i s h u n t i l c o u n t i n g . The date of p l a t i n g was recorded. A l l equipment used i n the d i g e s t i o n and p l a t i n g was d e d i c a t e d and kept c l e a n by r i n s i n g with d i s t i l l e d water a f t e r use and s t o r e d i n 10% HC1 which was changed r e g u l a r l y . Blank t e s t s were run o c c a s i o n a l l y ; no counts were ever recorded over 24h. p e r i o d s . 168 Alpha spectrometry. The d i s c s were counted over 24 hours on an ORTEC 576a Alpha spectrometer. The energy s c a l e of the spectrometer was c a l i b r a t e d u s i n g i t s i n t e r n a l t e s t peak. (5.0 mev) and an **lAm source (5.49 mev) o b t a i n e d from the TRIUMF F a c i l i t y a t U.B.C. Both polonium peaks ( 2 0 BPo= 5.11 Mev, 2 1 ° P o = 5.305 Mev) were i n t e g r a t e d over 250 channels by u s i n g the ORTEC "Region of I n t e r e s t * storage and r e c a l l f a c i l i t y . The t o t a l counts i n these peaks were recorded. These counts were converted i n t o 2 1 ° P o and thereby 2 1 ° P b a c t i v i t y u s i n g the program PB-CALC (S.E Calvert) s t o r e d on the boot d i s c of the ORTEC system. T h i s c a l c u l a t e s the 2 1 ° P o a c t i v i t y u s i n g the formula; A 2 1 ° P o = A 2 0 B P o x 2 1 ° P o counts sample wt. 2 o e P o counts where A = A c t i v i t y i n dpm/g. An e r r o r estimate based on c o u n t i n g s t a t i s t i c s was c a l c u l a t e d by; z 2 i o P o = •( (VlxVl ) - r(V2xV2) )x A a*°Po 100 where VI = e r r o r estimate as a % of a o s P o counts, V2 = e r r o r estimate as a % of 2 1 ° P o counts 169 A t e s t of instrument p r e c i s i o n was a l s o c a r r i e d out and the r e s u l t s are g i v e n i n Table A.I. A 2a value of 0.1 dpm/g. i s r e p o r t e d . TABLE A.I; Estimate of ORTEC Instrument P r e c i s i o n . SAMPLE WEIGHT COUNTS/24hrs DPM/G = 1 ° P o I 1.007 1300 + 36 6.61+.24 II 1.008 1262±35 6.72±.25 I I I 1.009 1369±37 6.72±.25 IV 1.003 1468±38 6 .28*.21 Mean 6.58 dpm/g. 2<r =0.42. RSD (2c-)= ±6.33% A well-mixed bulk sample of Core CPIII was used. T h i s was shaken f o r 30min. i n a mechanical shaker, reground and shaken again. Four sub-samples were run together with a blank. The blank recorded no counts. Sediment s o l u t i o n s were p l a t e d twice and no counts were measured on the second d i s c . APPENDIX B X-rav f l u o r e s c e n c e methods. A l l a n a l y s es were c a r r i e d out on an automated P h i l i p s PW 1400 spectrometer c o n t r o l l e d by a DEC PDT 11 microcomputer. A rhodium t a r g e t x-ray tube was used f o r e x c i t a t i o n . Samples f o r x-ray a n a l y s i s were the d r i e d and ground samples taken from core CPIV. A l l r e p o r t e d values have been c o r r e c t e d f o r d i l u t i o n by s e a s a l t and, where a p p r o p r i a t e , f o r the elemental composition of t h a t s a l t . The formulae used f o r these c o r r e c t i o n s are found i n Appendix C. Sample p r e p a r a t i o n ; Major elements. The major elements were determined u s i n g a f u s i o n method based on Norrish and Hutton (1969), u s i n g a sample p r e p a r a t i o n technique very s i m i l a r to t h a t p u b l i s h e d by Harvey et al. (1972). 0.4g. of ground, d r i e d sample was fused i n a Pt/Au c r u c i b l e i n a muffle furnace a t 1100 °C with 3.6g. of S p e c t r o f l u x 105 (Johnson and Matthey L t d . ) . The f l u x c o n s i s t s of l i t h i u m t e t r a b o r a t e ( 4 7 . 0 3 % ) , l i t h i u m carbonate( 36. 6 3%) and lanthanum oxide(16.34%), the r e c i p e recommended by Norrish and Hutton (1969). The two l i t h i u m compounds reduce the m e l t i n g temperature of the f l u x to 700 1 7 1 QC with f u l l f l u i d i t y a t 1000 °C. Lanthanum oxide i s used as a heavy absorber to produce high mass a b s o r p t i o n of the matrix and r e d u c i n g matrix d i f f e r e n c e s between samples and standards. I t s a d d i t i o n avoids the use o f a high sample d i l u t i o n and the consequent l o s s o f p r e c i s i o n t h a t would otherwise be r e q u i r e d to ensure a l i n e a r r e l a t i o n s h i p between f l u o r e s c e n t i n t e n s i t y and c o n c e n t r a t i o n . Weight l o s s on f u s i o n was made up with S p e c t r o f l u x 100 (100% L i t h i u m t e t r a b o r a t e , Johnson and Matthey Ltd.) T h i s maintained the lanthanum/sample r a t i o . Both f l u x e s were k i l n d r i e d and s t o r e d i n s e a l e d c o n t a i n e r s before use. The c o o l e d melt with added LaaB*C>7- was reheated to f l u i d i t y over a flame burner, poured i n t o an aluminium mold, quenched and pressed i n t o d i s c s by the a p p l i c a t i o n of a brass weight. T h i s process was c a r r i e d out on a h o t - p l a t e a t 400 °C. Sample p r e p a r a t i o n ; Minor elements. Trace or minor elements were determmined u s i n g 0.5g. subsamples of sediment. The ground, d r i e d sample was pressed i n t o a b o r i c a c i d backed p e l l e t a t 10 tons pressure i n a h y d r a u l i c p r e s s . For elements with wavelengths s h o r t e r than the Fe a b s o r b t i o n edge, matrix c o r r e c t i o n was c a r r i e d out u s i n g the Compton Ra t i o method of Reynolds (1963;1967). Sample a n a l y t e l i n e s , c o r r e c t e d f o r background, are r a t i o e d to the Compton peak of the Rh Ka l i n e . T h i s r a t i o p l o t t e d a g a i n s t the ppm. values of i n t e r n a t i o n a l standards p r o v i d e s the c a l i b r a t i o n f o r each element. Elements with wavelengths longer than the i r o n a b s o r p t i o n edge (Ba,V,Cr,Mn) were m a t r i x - c o r r e c t e d by r a t i o i n g the peak to a convenient background measured e i t h e r a d jacent to the element peak or i n a , s e c t i o n of the spectrum where there i s no i n t e r f e r e n c e by the peaks from other elements. No matrix c o r r e c t i o n s were a p p l i e d to the sodium i n t e n s i t i e s . For t h i s l i g h t element, there i s a c l o s e c o r r e l a t i o n between u n c o r r e c t e d c o n c e n t r a t i o n s and those p u b l i s h e d f o r i n t e r n a t i o n a l rock standards. S p e c t r a l i n t e r f e r e n c e s of T i on V and Ba, Rb on Y, N i , Sr on Zr and V on Cr were c o r r e c t e d i n a c o n v e n t i o n a l manner by determining the r a t i o s between Ka and KB i n t e n s i t i e s on pure i n t e r f e r i n g element standards and by a p p l y i n g the a p p r o p r i a t e c o r r e c t i o n s to the net i n t e n s i t i e s o f the a f f e c t e d elements. Instrument c o n d i t i o n s . The instrument c o n d i t i o n s used are l i s t e d i n Table B.I. Sulphur and Mo , which were measured u s i n g d e d i c a t e d measuring programs, c a l i b r a t i o n s and standards, are i n c l u d e d with the major and minor elements, r e s p e c t i v e l y . Instrument d r i f t was c o r r e c t e d by running a monitor before each s e t of samples and standards. Sample i n t e n s i t i e s are then r a t i o e d to the monitor i n t e n s i t i e s . 173 Standards used i n the c a l i b r a t i o n s were run as unknowns together with the samples i n order to check f o r instrument performance d u r i n g the analyses o f groups o f samples. The r e s u l t s of these analyses are r e p o r t e d i n Tables B . I I I , B.VIII, B.X and B.XII. I t was found t h a t no f u r t h e r c o r r e c t i o n s were necessary. Instrument c a l i b r a t i o n . The spectrometer was c a l i b r a t e d u s i n g i n t e r n a t i o n a l geochemical r e f e r e n c e standards whose element c o n c e n t r a t i o n s are found i n Abbey (1980). Table B.II l i s t s those used f o r the d e t e r m i n a t i o n o f the major elements and shows a comparison between measured values and the p u b l i s h e d values o f the standards. Instrument c a l i b r a t i o n f o r the minor elements was c a r r i e d out us i n g l.Og. standards. A comparison o f l.Og.and 0.5g. p e l l e t s u s i n g bulk Saanich sediment (Table B.VI) shows s a t i s f a c t o r y agreement. Since the i n t e r n a t i o n a l standards used do not c o n t a i n h i g h enough c o n c e n t r a t i o n s o f S and Mo, c a l i b r a t i o n s f o r these two elements were c a r r i e d out u s i n g standards made from bulk b a s a l t s p i k e d with a known amount o f the element concerned and converted i n t o a d i l u t i o n s e r i e s to provide a c a l i b r a t i o n c o v e r i n g c o n c e n t r a t i o n s expected i n the samples. Molybdenum standards were made by s p i k i n g the b a s a l t with Specpure MoOa while the sulphur standards were made with both s u l p h i d e (FeS 2) and sulphate (Na2S0.*) s p i k e s 174 to make sure t h a t any d i f f e r e n c e i n the c a l i b r a t i o n due to the o x i d a t i o n s t a t e of the sulphur was accounted f o r . Estimates of accuracy and p r e c i s i o n . The mean d i f f e r e n c e s between p u b l i s h e d and measured c o n c e n t r a t i o n s of each element i n the standards run as unknowns were used as an estimate of the accuracy of the method. I t must be noted, however, t h a t the standards were a l s o used f o r c a l i b r a t i o n so t h a t t h i s method i s not an unbiased estimate of accuracy. These estimates are g i v e n as MDV (Mean d i f f e r e n c e between p u b l i s h e d and measured values) i n Table B.III f o r major elements. Table B.VIII f o r the minor elements. Table B.X f o r sulphur and Table B.XII f o r molybdenum. Estimates of instrument p r e c i s i o n and between sample p r e c i s i o n f o r the major elements are r e p o r t e d i n Tables B.IV and B.V, r e s p e c t i v e l y . Instrument p r e c i s i o n was determined by running one sample of w e l l mixed bulk Saanich sediment s i x times and r e p o r t i n g the 2a r e l a t i v e standard d e v i a t i o n from the mean of these s i x v a l u e s . Between sample p r e c i s i o n was determined by running f i v e samples of the same sediment, prepared u s i n g the same method as t h a t used f o r the core samples. These estimates were determined on a sample of w e l l mixed bulk Saanich c e n t r a l b a s i n sediment s i n c e the core samples d i d not provide enough m a t e r i a l . 175 Instrument p r e c i s i o n f o r the d e t e r m i n a t i o n of the minor elements was estimated u s i n g the same method except t h a t the bulk Saanich sample was run ten times. 2 a RSD values from t h i s t e s t are r e p o r t e d i n Table B.VI, Table B.l IRF Instrument Conditions. Si Al Fe Hg Ca K P Ti S Tub* kV 80 60 60 30 30 60 30 60 60 Tub* »A 20 40 40 60 10 40 60 40 ' 40 Crystal 2 2 I 4 I 1 3 1 3 Counter F F F F F F F F F Peak '29 109.3614S.3SS7.66 45.34 113.29136.76141.1786.24 110.77 Background +1.6 •1.4 •2.0 •3.0 •1.0 •20 -1.3 -1.6 -1.2 -1.5 Collimator C C C C C F C C C Count Tint 40 40 20 100 20 20 100 40 80 Peak Count Tin* 20 20 10 SO 10 10 50 10 40 Background Ir y Sr Rb Zn Cu- Ni Hn V Cr Ba Na Ho Tube kV 60 60 60 60 60 60 60 60 60 60 60 30 60 Tube tA 40 40 40 40 40 40 40 40 40 40 40 60 40 Crystal 1 1 1 1 1 1 1 1 1 1 1 4 3 Counter 8 8 S S FS FS FS F F F F F S Peak '29 22.49 23.7B 23.IS 26.60 41.73 44.98 4B.60 63.11 77.37 69.49 87.21 55.26 28.83 Background •0.74 •0.6 •0.6 •0.6 •0.72 •1.2 •l.S •4.0 •1.0 •1.2 •0.7 •2fl -0.74 -0.6 -0.6 -0.6 -0.62 -0.6 -1.7 -0.7 Collimator F F F F F F F C C C F C F Count Tin* 100 100 100 100 100 100 100 100 100 100 200 100 200 Peak Count Tine 40/40 40/40 40/40 40/40 40 40 40 40 40 40 100 40 20/20 Background t RHODIUM TUBE t All elements measured on the Kalpha line except Ba on Lbeta. t Counters! F = flow using 90Z Ar I 101 CH4. S « scintillation counter. t Collimators: C = corse; 4B0um. F * fine; 160um. $ Cu- Aluminium filter over the x-ray tube. I CRYSTALS: 1 = Lithium fluoride (200 cut). 2 - Pentaerythritol. 3 = Sermanium. 4 « Thallium acid phthalate. 5 * Lithium fluoride (220 cut) tVacuum path used throughout. tCount time in Seconds. 177 Table B.II Standards used for the Calibration of Major Elements. Name Si Al Fe Mg Ca K P Ti AGV-1 P 59.61 17.19 6.8 1.52 4.94 2.92 0.51 1.06 M 59.27 17.07 6.83 1.58 4.94 2.94 0.5 1.05 G-2 P 69.22 15.4 2.68 0.75 1.96 4.46 0.13 0.48 H 67.17 15.41 2.73 0.75 1.95 4.42 0.13 0.5 GSP P 67.32 15.28 4.29 0.97 2.03 5.51 0.28 0.66 H 67.63 15.3 4.31 0.99 2.03 5.59 0.26 0.67 BCR P 13.72 13.42 3.48 6.97 1.7 0.36 2.26 M 13.96 13.43 3.71 6.93 1.75 0.37 2.22 GA P 2.8 0.95 2.45 4.03 0.12 0.38 H 2.73 0.91 2.42 4 0.12 0.38 NIM-S P 63.63 17.34 1.4 0.46 0.68 15.35 0.12 0.04 N 63.97 17.14 1.4 0.43 0.67 15.24 0.11 0.03 SY-2 P 60.1 12.12 6.28 2.7 7.98 4.48 0.43 0.14 M 59.81 12.14 6.28 2.67 7.92 4.51 0.44 0.14 MRG-1 P 39.32 8.5 17.83 13.49 14.77 0.18 0.06 3.69 N 39.23 8.37 17.8 13.06 14.79 0.17 0.06 3.68 DR-N P 52.88 17.56 9.69 4.47 7.09 1.73 0.25 1.1 H 52.17 17.52 9.66 4.55 7 1.74 0.23 1.06 NIM-G P 75.7 12.08 2.01 0.06 0.78 4.99 0.09 H 75.44 12.23 1.99 0.05 0.8 4.96 0.1 BHVO P 49 7.31 11.33 0.54 0.28 2.69 M 49.95 7.37 11.48 0.52 0.27 2.72 M- MEASURED VALUES. P- PUBLISHED VALUES. * Blanks indicate that the standard was not used in calibration. 178 Table B.III Standards run as unknowns during Hajor Element Analysis. • NAHE Si Al Fe Mg Ca K P Tl GSP-1 68.16 15.55 4.34 1.05 2.04 5.49 0.3 0.66 M 67.32 15.28 4.29 0.97 2.03 5.51 0.28 0.66 P SY-2 60.03 12.16 6.3 2.76 7.9 4.47 0.45 0.13 H 60.1 12.12 6.28 2.7 7.98 4.48 0.43 0.14 P AGV-1 59.13 17.21 6.83 1.53 4.92 2.91 0.5 1.07 M 59.61 17.19 6.8 1.52 4.94 2.92 0.51 1.06 P GA 68.61 14.67 2.73 0.92 2.24 4.03 0.12 0.37 H 68.96 14.51 2.8 0.95 2.45 4.03 0.12 0.38 P BCR-1 54.48 13.81 13.47 3.66 6.92 1.75 0.37 2.23 M 54.53 13.72 13.42 3.48 6.97 1.7 0.36 2.26 P MDV 0.4% 0.12% 0.04% 0.07% 0.07% 0.02% 0.01% 0.01% MDV- Mean Difference between values for each element. Can be taken as an estimate of absolute accuracy H - Measured values. P » Published values. Table B.IV Instrument P r e c i s i o n Estimate for Major Elements Cycle % S i %A1 %Fe %Ca %K %Mg %P % T i %S 1 59.33 11.97 5.90 2.03 1.55 2.47 0.18 0.7 1.27 2 59.44 11.77 5.96 2.04 1.53 2.47 0.18 0.7 1.29 3 59.21 11.88 5.95 2.05 1.53 2.48 0.19 0.69 1.28 4 59.23 11.89 5.96 2.11 1.54 2.54 0.2 0.7 1.29 5 59.23 11.89 5.97 2.08 1.50 2.51 0.21 0.7 1.28 6 59.26 11.95 5.97 2.08 1.55 2.39 0.21 0.69 1.29 MEAN 59.28 11.89 5.95 2.07 1.53 2.48 0.19 0.696 1.28 2sigma 0.18 0.14 0.05 0.06 0.04 0.1 0.03 0.01 0.02 RSD 2s0.03% 1.18% 0.89% 2.91% 2.43% 4.07% 14.51%1.48% 1.28% * Analysis run on one sample of bulk Saanich sediment. Table B.V Between Sample Precisio n estimate for the Major Elements. SAMPLE % S i %A1 %Fe %Ca %Mg %K %P % T i SAN 1 60.08 12.06 5.97 2.08 2.58 1.57 0.19 0.7 SAN 2 60.37 12.1 6.05 2.11 2.5 1.62 0.2 0.7 SAN 3 60.01 12.21 6.06 2.07 2.46 1.53 0.19 0.7 SAN 4 60.7 11.9 6.09 2.15 2.57 1.63 0.2 0.69 SAN 5 61.38 12.16 6.24 2.12 2.6 1.64 0.19 0.7 MEAN 60.50 12.08 6.08 2.11 2.54 1.60 0.19 0.697 RSD 2s 1.7 2.0 3.3 3.0 4.5 5.9 5.3 0.005 * RSD 2sigma can be taken as an estimate of precision. * Test run on fi v e samples of bulk Saanich central basin sediment using the same preparation method as that used for the core samples. 180 Table B.VI Minor Element Comparison between l.Og. and 0.5g. p e l l e t s and an Estimate of Instrument Precision. ELMT. Precision. 1.0 g.* 0.5 g.* Ba 5+10% 438+38 440+34 Cr 5+10% 85+10 83+6 Cu 10+20% 4.5+9% 29+10 29+10 Mn 4+8% 565+38 557+24 Ni 15+30% 8+16% 25+6 26+6 Pb 18+36% 19+10 20 + 10 Rb 6 + 12% 51+8 51+8 Sr 2+4% 196+26 194+24 V 3+6% 105+8 105+6 Y 10+20% 20+4 21+4 Zn 6 + 12% 114+18 115+16 Zr + 13% 109+14 109+14 Na 1+2% 2.2+.1 2.2+.08 Mo +8% 42 + 3 41+3 * A l l samples were made from Bulk Saanich central basin sediment. Each sample was measured 6 times. Errors are two standard deviations on 30 measurements. * Precisi o n estimates from a one gram p e l l e t run 10 times. Values show + 2sigma RSD. Ni 1st value <20ppm, 2nd value >30ppm. Cu 1st value <25ppm, 2nd value >50ppm. (R.Francois, pers.comm). Table P.VII Standards used for the Calibration of Hinor Eletents. l.Og. Pellets. Values in ppa. Ma in I by weight Mate Zr V Sr Rb Zn Cu Ni Hn V Cr Ba ZNa A8V-1 H 230 19 660 67 86 59 15 728 125 1200 P 223 22 666 67 86 60 16 758 132 1145 6SP-1 H SOO 29 9 326 1300 2.81 P SIO 38 13 310 1326 2.78 6-2 H 300 170 84 10 265 8 4.06 P 293 167 83 8 244 5 4.22 BCR H 185 40 47 125 16 10 1350 680 3.3 P 189 35 48 129 16 10 1307 698 3.13 6A N ISO 21 175 80 7 700 38 12 3.55 P 134 26 181 84 6 679 46 10 3.33 SY2 H 130 275 220 250 460 P 12S 270 213 241 445 MRS M 10S 16 B 50 0.71 P 96 12 8 46 0.71 DR-M H 30 3 P 26 2.95 BN H 105 26 230 180 120 260 P 110 24 225 156 157 240 BR H 72 1050 3.07 P 65 1087 3.31 BHVO H 180 27 420 10 140 1316 135 P 181 24 424 9 139 1379 132 BEN H 30 120 72 1548 1050 P 27 115 77 1511 1038 NIH-D H 2900 10 P 2875 10 NIH-N H 68 14 1393 100 2.46 P 70 13 1415 114 2.62 NIH-6 N 145 10 320 2 12 3.36 P 143 10 316 1.66 IS 3.15 NIH-S H 33 S30 10 7 80 P 33 534 9 4 88 ASK-1 H 105 7 110 40 P 106 8 105 43 ASK-2 H 100 220 90 P 96 223 70 H 9 Measured * Blanks are values. P • Published values, standards not used in that eletents calibration. Table B.VIII Standards run as Unknowns during Hinor Element Analysis. Name Zr V Sr Rb Zn Cu Ni Hi V Cr Ba ZNa A6V-1 eye 1*1 193 17 601 61 82 S3 13 710 126 2 936 3.72 cyde2 201 20 593 53 66 37 5 748 128 0 975 3.69 cyde3 201 17 603 60 70 37 8 744 129 0 942 3.69 Mean 199 18 600 57 73 43 9 734 128 0.6 958 3.7 S.D 3 1 3 3 7 8 3 17 I 16 0.01 Pub 223 22 666 67 86 60 16 738 132 10 1145 3.75 6A cydel 136 33 340 177 83 11 S 698 48 10 823 3.3 cyde2 133 33 342 179 93 IS 12 665 44 14 799 3.24 cyde3 139 33 342 183 90 19 9 47 12 777 3.23 Hean 137 34 341 180 89 IS 9 684 46 12 800 3.26 S.D 2 1 1 3 3 3 3 14 2 1 20 0.03 Pub 134 26 310 181 84 16 6 680 47 11 830 3.33 cydel 431 38 222 229 119 31 14 286 79 7 1311 2.7 cyde2 453 41 228 231 118 32 10 285 78 5 1201 2.67 cyde3 430 33 225 234 122 33 11 274 76 S 1176 2.65 Hean 451 38 22S 231 120 32 12 282 78 6 1229 2.67 S.D 1 2 2 2 2 1 2 5 1 1 59 0.02 Pub 520 38 250 250 103 33 13 310 54 12 1326 2.78 cydel 265 14 446 157 82 8 I 242 66 3 1789 4.19 cyde2 268 18 457 159 97 8 0 231 63 2 1651 4.08 cyde3 273 22 470 158 99 8 7 233 68 S 182S 4.1 Hean 269 18 458 158 93 8 3 236 66 4 175S 4.12 S.D 4 3 10 0.5 8 3 3 2 1.3 75 0.05 Pub 293 11 480 167 83 8 3 244 36 5 1900 4.22 cydel iai 21 986 39 127 62 132 1256 292 237 948 3.21 cyde2 183 22 983 34 117 57 140 1315 301 253 1035 3.19 cyd*3 180 26 986 37 115 65 152 1308 297 258 901 3.3 Hean 181 23 985 37 120 61 148 1293 297 249 961 3.23 8.D 1 2 1.5 2 5 3 6 26 4 9 55 0.05 Pub 250 30 1300 47 150 65 142 1548 240 380 1087 3.31 39 5 91 10 15 9 7 124 23 30 121 0.08 HDV a Hean difference between values. Can be taken as an estinate of absolute accuracy, but s t i l l contains error inherent in the calibration. Table B.IX C a l i b r a t i o n Standards f o r Sulphur. NAME P u b l i s h e d Measured S I 4.31 4.16 S I I 3.23 3.31 S V 0.95 0.96 S VI 0.73 0.78 S VII 0.47 0.38 S VIII 0.36 0.4 Table B.X Standards run as unknowns d u r i n g Sulphur A n a l y s i s . NAME P u b l i s h e d Measured S V S IV S I I S VIII MDV =0.0 0.95 1.52 3.23 0. 36 (Mean d i f f . 0.92 1.54 3.25 0.34 between M and P) S I-S VIII are a s y n t h e t i c d i l u t i o n s e r i e s . Table B.XI C a l i b r a t i o n Standards for Molybdenum. NAME Published Measured ASK-2 60 64 TS 130 141 SGR-1 36 30 POMO II 208 194 POMO III 149 152 POMO V 48 42 POMO VI 20 16 POMO VII 11 12 * A l l are l.Og. p e l l e t s . * POMO are a d i l u t i o n series made from basalt spiked with Specpure Mo. Table B.XII Standards run as unknowns during Molybdenum Analysis. NAHE Published Measured 1 SD POMO II 208 205 0. 78 POMO IV 92 82 0. 91 ASK-2 60 69 2. 33 POMO V 48 41 1. 18 * Measured values are the Mean of two measuring cycles. 1 SD reported. MDV- 7.3ppm.(Mean d i f f . between M and P) APPENDIX C C h l o r i n e a n a l y s i s . The amount of c h l o r i n e , and thereby the s a l t content of the d r i e d samples, was determined v o l u m e t r i c a l l y u s i n g a method adapted from Strickland and Parsons (1968). Around 100 mg. of sample was a c c u r a t e l y weighed i n t o a c l e a n p l a s t i c c e n t r i f u g e tube, 5ml. of d i s t i l l e d water was added and the mixture was s t i r r e d on a vortex s t i r r e r f o r 10 minutes to d i s s o l v e the s a l t . The sample was then c e n t r i f u g e d f o r 10 minutes a t 3000 rpm. The supernatant was c o l l e c t e d by p i p e t t e and s t o r e d i n p l a s t i c v i a l s . The amount of s o l u t i o n remaining i n the c e n t r i f u g e tube was estimated by the weight d i f f e r e n c e between the wet and dry sediment r e s i d u e . T h i s was done e i g h t times d u r i n g the a n a l y s i s of the CPIV samples. The mean weight of water r e t a i n e d was found to be 0.28g. (2a=0.04) The volume of water used i n the c a l c u l a t i o n s was thus taken as 4.72ml. r a t h e r than 5.0ml. The C l - was t i t r a t e d a g a i n s t AgN0 3 (0.1484 M). i n a l i q u o t s of 1ml. of the supernatant s o l u t i o n u s i n g a Gilmont m i c r o b u r e t t e r e a d i n g to three decimal p l a c e s . Potassium dichromate was used as the i n d i c a t o r and the s o l u t i o n was s t i r r e d d u r i n g t i t r a t i o n with a t e f l o n coated s t i r - b a r . The t i t r a t i o n s were c a r r i e d out i n d u p l i c a t e and the s o l u t i o n 186 was s t i r r e d q u i c k l y on the Vortex s t i r r e r before each a l i q u o t was taken. %C1 was c a l c u l a t e d from the f o l l o w i n g : [C1-] = [AqN031x vol.AqN03 sample volume gCl/1. = [C1-] x 35.45 (atomic wt. o f Cl) gCl/sample = gCl/1. x 4.72 1000 %C1 = gCl/sample x 100 sample wt.(g) These values were then used to c o r r e c t a l l chemical data f o r d i l u t i o n by s a l t and, where a p p r o p r i a t e , f o r a d d i t i o n o f the element concerned because of i t s c o n c e n t r a t i o n i n s e a s a l t . These c o r r e c t i o n s were performed u s i n g the f o l l o w i n g formulae: [ E l ] . . ! * = [ E l ] x 100  (100-1.82(%C1)) %Nacor = %Na -0.556 (%C1) %Mgcor = %Mg -0.067 (%C1) %Cacor = %Ca -0.021 (%C1) %Kcor = %K -0.02 (%C1) ppm Br Br -34.6 (%C1) ppm Sr = Sr -4.13 (%C1) ppm S = S -16.6 (%C1) * Sulphur numbers c a l c u l a t e d with t h i s c o r r e c t i o n r e f l e c t o x i c seawater c o n d i t i o n s . In Saanich I n l e t the anoxic c o n d i t i o n s which predominate w i l l reduce seawater su l p h a t e ; thus sulphur numbers r e p o r t e d are shown as Sox 1 8 7 where t h i s c o r r e c t i o n i s employed, and Sanox where no second c o r r e c t i o n was c a l c u l a t e d s i n c e the S u l p h a t e : C h l o r i n e r a t i o of the cores pore waters i s unknown. The valu e s of sulphur f o r CPIV w i l l l i e i n the range between these numbers. Table C.I C h l o r i d e C a l c u l a t i o n s . ml. AgN03 SNPL WT.(g) Runl Run2 MEAN % C l . % WATER 86 0.103 0.444 0.445 0.444 11.3 86.8 85 0.108 0.456 0.455 0.455 . 11.0 86.6 84 0.108 0.457 0.457 0,457 11.1 86.6 83 0.106 0.453 0.453 0.453 11.2 86.7 82 0.104 0.489 0.485 0.487 12.3 87.7 81 0.104 0.503 0.503 0.503 12.6 88.1 80 0.101 0.546 0.546 0.546 14.2 89.2 79 0.104 0.557 0.556 0.556 13.9 89.1 78 0.104 0.602 0.601 0.601 15.1 89.8 77 0.102 0.589 0.59 0.589 15.1 89.8 76 0.109 0.64 0.639 0.639 15.3 90.0 75 0.108 0.596 0.6 0.598 14.5 89.4 74 0.106 0.679 0.677 0.678 16.7 90.7 73 0.104 0.643 0.642 0.642 16.3 90.5 72 0.106 0.673 0.669 0.671 16.5 90.6 71 0.102 0.598 0.598 0.598 15.4 90.0 70 0.102 0.668 0.667 0.667 17.2 90.9 69 0.102 0.637 0.636 0.636 16.4 90.5 68 0.108 0.836 0.839 0.837 20.2 92.2 67 0.107 0.666 0.662 0.664 16.2 90.5 66 0.104 0.724 0.723 0.723 18.3 91.4 65 0.108 0.617 0.616 0.616 14.9 89.7 64 0.108 0.771 0.774 0.772 18.8 91.6 63 0.101 0.634 0.635 0.634 16.4 90.5 62 0.105 0.662 0.662 0.662 16.5 90.6 61 0.106 0.579 0.58 0.579 14.4 89. 3 60 0.104 0.715 0.717 0.716 18.0 91. 3 59 0.102 0.673 0.675 0.674 17. 3 91.0 58 0.104 0.751 0.751 0.751 19.0 91.7 57 0.103 0.548 0.548 0.548 13.9 89.0 56 0.105 0.627 0.626 0.626 15.6 90.1 55 0.104 0.507 0.508 0.507 12.8 88.2 54 0.106 0.582 0.583 0.582 14.4 89.4 53 0.109 0.547 0.545 0.546 13.1 88.4 52 0.107 0.613 0.613 0.613 15.0 89.7 51 0.111 0.527 0.527 0.527 12.4 87.9 50 0.102 0.6 0.601 0.600 15.4 90.0 * M o l a r i t y AgN03 = 0.1484. * Water co n t e n t c a l c u l a t e d f o r 31%. APPENDIX D.  Carbon, n i t r o g e n and carbonate a n a l y s i s T o t a l carbon and n i t r o g e n were measured by gas chromatography on a C a r l o - E r b a model 1106 CHN a n a l y s e r . The b a s i s o f the method employed by t h i s equipment i s d e s c r i b e d by Pella and Colombo (1973). The sediment samples are packed i n t o t i n f o i l cups and combusted a t 1050 °C i n a quartz tube f l u s h e d by a continuous stream o f helium and oxygen. F l a s h combustion i s primed by the o x i d a t i o n o f the t i n c o n t a i n e r and q u a n t i t a t i v e combustion, or f u l l o x i d a t i o n , occurs as the gas passes over C r 2 0 3 . Excess oxygen i s removed by p a s s i n g the gas over heated copper which a l s o reduces n i t r o u s oxides to n i t r o g e n . N 2, C0 2 and HzO are separated i n t h a t order by a chromatographic column and are measured by a thermal c o n d u c t i v i t y d e t e c t o r . The instrument was c a l i b r a t e d and the method s t a n d a r d i s e d u s i n g a c e t a n e l i d e (CHaCONHCeHo) which c o n t a i n s 71.09% carbon and 10.36% n i t r o g e n . Each run c o n s i s t e d of three blanks, to assure t h a t the system was f l u s h e d before samples were run, s i x standards and 14 samples. Approximately 3.0mg. of d r i e d sediment was a c c u r a t e l y weighed i n t o a t i n f o i l cup on a M e t t l e r microbalance and pinched c l o s e d . Prepared samples were kept i n a d e s s i c a t o r i f not immediately run. Samples were run i n 190 d u p l i c a t e and t r i p l i c a t e where the f i r s t two runs showed a marked d i f f e r e n c e i n r e s u l t . A n a l y t i c a l p r e c i s i o n was estimated by running f i v e samples of bulk Saanich sediment. The r e s u l t s are r e p o r t e d i n Table D.I. P r e c i s i o n i s estimated by the RSD (2o) of ±0.73% f o r carbon and ±2.6% f o r n i t r o g e n . The r e s u l t s o b t a i n e d from the a n a l y s i s of C P I V samples are presented i n t a b l e s D.II and D.III. Values are s a l t - c o r r e c t e d and the C o r 9 value i s C*©*.- C e.rbon«t.. Determination of carbonate carbon. Carbonate carbon was determined on the core samples by coulometry. Approximately 25mg. subsamples of the d r i e d sediment was a c c u r a t e l y weighed i n t o c l e a n g l a s s r e a c t i o n tubes. These were then a t t a c h e d to a Coulometrics Inc. model number 5010 coulometer and f l u s h e d i n a C O a - f r e e a i r - s t r e a m . A f t e r two minutes, 2ml. of 10% HCl i s added to the r e a c t i o n cup and the cup i s heated to around 60 °C. The C0 2 generated i s c a r r i e d to a t i t r a t i o n c e l l c o n t a i n i n g a s o l u t i o n o f ethanolamine and an i n d i c a t o r . The s t r o n g t i t r a t a b l e a c i d produced by the r e a c t i o n of the C0 2 with the ethanolamine i s t i t r a t e d with OH - ions produced by a s i l v e r e l e c t r o d e . The end p o i n t i s determined p h o t o m e t r i c a l l y by the l a c k of c o l o u r change i n the s o l u t i o n . 191 The amount of c u r r e n t r e q u i r e d to produce the 0H~ ions i s i n t e r g r a t e d and converted i n t o ugC. T h i s value i s converted i n t o % C c « ^ b or % T o t a l i n o r g a n i c carbon by: %Cc«rb = UgC CD2 — UgCblank x 100 sample wt. The samples were run i n d u p l i c a t e and the mean value used f o r the c a l c u l a t i o n of %C c.rb. Blanks were run a t i n t e r v a l s d u r i n g the a n a l y s i s and showed a maximum value of 5.7ugC while sample valu e s ranged from 40-180 ugC. C o r r e c t i o n s were made f o r these blank v a l u e s . A standard o f pure CaCOa (%C c « r t > = 12.0) was a l s o run four times d u r i n g measurement. A mean value o f 12.12%C = « r n was determined (2a = 0.14) Thus an estimate o f p r e c i s i o n f o r t h i s a n a l y s i s i s g i v e n by the RSD (2a)= ±1.2%. The r e s u l t s o b tained by t h i s method are presented i n Table D.III and are c o r r e c t e d f o r d i l u t i o n by s a l t . % C » r b , used i n the c a l c u l a t i o n of %Cora, and %CaC0 3 are both presented. Table D.I Estimate o f P r e c i s i o n f o r the a n a l y s i s o f Carbon and N i t r o g e n . SMPL MT mg. %C %N I 4.196 2.913 0.314 II 4.931 2.905 0.304 I I I 4.093 2.934 0.307 IV 4.149 2.921 0. 312 V 4.31 2.919 0. 309 MEAN 2.918 0.309 2sigma 0.02 0.008 RSD 0.73 2.6 * A n a l y s i s performed on a w e l l mixed bulk Saanich c e n t r a l b a s i n sediment. Table D.II R e s u l t s o f N i t r o g e n A n a l y s i s . SMPL Runl Run2 Run3 MEAN %C1 %N DEPTH 86 0.47 0.43 0. 24 11.3 0.50 0 85 0.46 0.51 0. 45 0. 32 11.0 0.53 3.8 84 0.45 0.43 0. 43 0. 29 11.1 0.48 4.2 83 0.38 0.4 0. 19 11.2 0.43 6.4 82 0.37 0.39 0. 19 12.3 0.43 7.5 81 0.45 0.44 0. 23 12.6 0.50 7.7 80 0.43 0.43 0. 22 14.2 0.49 9.5 79 0.38 0.39 0. 46 0. 26 13.9 .0.47 9.8 78 0. 38 0.4 0. 32 0. 26 15.1 0.42 10.9 77 0.41 0.41 0. 21 15.1 0.47 11.3 76 0.41 0.41 0. 21 15.3 0.47 11.5 75 0.4 0.39 0. 20 14.5 0.45 11.8 74 0.35 0. 33 0. 18 16.7 0.40 12.7 73 0. 39 0. 37 0. 20 16. 3 0.44 13. 3 72 0. 36 0. 34 0. 18 16.5 0.41 14.1 71 0.34 0.35 0. 31 0. 23 15.4 0. 38 15.4 70 0.36 0. 38 0. 18 17.2 0.43 16.2 69 0.38 0.35 0. 19 16.4 0.42 17.1 68 0.36 0.35 0. 18 20.2 0.43 18.3 67 0.46 0.35 0. 31 0. 27 16.2 0.43 18.7 66 0.33 0.32 0. 17 18.3 0.38 18.9 65 0.35 0.36 0. 18 14.9 0.41 19.5 64 0.29 0.33 0 .3 0. 21 18.8 0.36 19.7 63 0.34 0.32 0. 17 16.4 0.38 19.9 62 0.33 0.36 0. 17 16.5 0.40 20.6 61 0.35 0.35 0. 18 14.4 0.40 21.1 60 0.31 0.3 0. 16 18.0 0. 36 22.4 59 0. 36 0. 34 0. 18 17. 3 0.41 22.6 58 0.34 0. 37 0. 17 19.0 0.42 23.2 57 0.41 0.41 0. 21 13.9 0.47 24.3 56 0.49 0.48 0. 44 0. 32 15.6 0.54 27.2 55 0.39 0.41 0. 36 0. 27 12.8 0.44 27.7 54 0.39 0.38 0. 20 14.4 0.44 28.4 53 0.41 0.43 0. 21 13.1 0.48 29.7 52 0.36 0.38 0. 18 15.0 0.43 30.6 51 0.49 0.48 0. 25 12.4 0.55 31.6 50 0.42 0.4 0. 21 15.4 0.47 32.2 Table D.III Results of Carbon and Carbonate Analysis. SMPL Runl Run2 Run3 MEAN %C1 %Ctot %Corg.%Ccarb%CaC03 DEPTH 86 4.88 4.84 4.86 85 5.1 5.51 5.22 5.28 84 5.09 4.74 4.86 4.90 83 4.56 4.73 4.65 82 4.44 4.55 4.50 81 4.33 4.44 4. 39 80 4.4 4.38 4. 39 79 3.92 4.54 4.23 78 4.01 3.74 3.88 77 4.28 4.21 4.25 76 4 3.96 3.98 75 3.95 4.06 4.01 74 3.62 3.37 3.50 73 3.78 4 3.89 72 3.77 3.65 3.71 71 3.26 3.33 3.13 3.24 70 3.51 3.7 3.61 69 3.3 3.46 3.38 68 3.5 3. 38 3.44 67 3. 39 4. 25 3. 26 3.63 66 3.11 3.09 3. 10 65 3.43 3.5 3.47 64 3.25 2.85 3.1 3.07 63 3. 32 3.2 3. 26 62 3.54 3.3 3.42 61 3.46 3.56 3.51 60 3.15 3.22 3.19 59 3.71 3.58 3.65 58 3.46 3.28 3.37 57 3.91 3.81 3.86 56 4.79 4.58 4.56 4.64 55 3.85 4.18 3.9 3.98 54 3.72 3.68 3.70 53 4.24 4.07 4.16 52 3.71 3.69 3.70 51 4.73 4.65 4.69 50 3.87 3.82 3.85 * Corg. • Ctot-Ccarbonate 11.3 5.41 4.79 0.62 5.19 0 11.0 5.86 5.03 0.83 6.94 3.8 11.1 5.44 4.61 0.83 6.94 4.2 11.2 5.17 4.53 0.63 5.28 6.4 12. 3 5.05 4.33 0.72 5.99 7.5 12.6 4.94 4.42 0.52 4.32 7.7 14.2 5.01 4.55 0.47 3.90 9.5 13.9 4.82' 4.41 0.41 3.42 9.8 15.1 4.46 4.18 0.28 2.30 10.9 15.1 4.88 4.57 0.31 2.59 11.3 15.3 4.59 4.29 0.30 2.50 11.5 14.5 4.59 4.25 0.33 2.77 11.8 16.7 4.08 3.76 0.32 2.63 12.7 16.3 4.52 4.23 0.29 2.42 13.3 16.5 4.32 4.04 0.28 2.33 14.1 15.4 3.74 3.46 0.28 2.31 15.4 17.2 4.22 3.97 0.26 2.15 16.2 16.4 3.93 3.67 0.27 2.23 17.1 20.2 4.14 3.86 0.28 2.30 18.3 16.2 4.22 3.93 0.29 2.42 18.7 18.3 3.67 3.44 0. 22 1.87 18.9 14.9 3.98 3.67 0. 31 2.59 19.5 18.8 3.64 3.36 0.29 2.38 19.7 16.4 3.79 3.55 0.24 2.04 19.9 16.5 3.99 3.75 0.23 1.94 20.6 14.4 4.01 3.76 0.25 2.10 21.1 18.0 3.76 3.53 0.22 1.87 22.4 17.3 4.28 3.92 0.35 2.93 22.6 19.0 4.01 3.78 0.23 1.88 23.2 13.9 4.40 4.12 0.27 2.28 24.3 15.6 5.37 5.15 0.22 1.83 27.2 12.8 4.49 4.21 0.27 2.26 27.7 14.4 4.23 3.97 0.26 2.19 28.4 13.1 4.70 4.42 0.28 2. 36 29.7 15.0 4.25 4.04 0.22 1.82 30.6 12.4 5.27 4.95 0.33 2.72 31.6 15.4 4.44 4.23 0.21 1.73 32.2 195 APPENDIX E P r e p a r a t i o n of samples f o r enumeration of diatoms. Subsamples of the sediments were prepared f o r diatom f r u s t u l e c o u n t i n g by the use o f a method based upon the permanganate method Hasle and Fryxell (1970) and Hendey (1974), the p e r o x i d e / c e n t r i f u g e method of Schrader (1973), and the potassium p e r s u l p h a t e method p u b l i s h e d by Ma and Jeffrey (1978) . These methods were a l l i n v e s t i g a t e d i n order to f i n d one t h a t ; a: was time e f f i c i e n t . b: preserved d e l i c a t e diatoms, such as many of the Chaetoceros s p e c i e s . c: broke up the o r g a n i c aggregates found to be common i n Saanich I n l e t sediments. d: s u c c e s s f u l l y cleaned the diatom f r u s t u l e s o f adhered o r g a n i c matter f a c i l i t a t i n g i d e n t i f i c a t i o n of s p e c i e s by f r u s t u l e a r e o l a e p a t t e r n s . I t was found t h a t the permanganate method of Hasle and Fryxell (1970) and Hendey (1974) which r e q u i r e d b o i l i n g each sample i n the c l e a n i n g s o l u t i o n , was time consuming, while the p e r o x i d e / c e n t r i f u g i n g method of Schrader (1973) tended to break up the more d e l i c a t e s p e c i e s . The pers u l p h a t e method of Ma and Jeffrey (1978) was found to be the most time e f f i c i e n t , a l l o w i n g batches o f 30 samples to 196 be processed a t one time. The samples were allowed to s e t t l e and c e n t r i f u g a t i o n avoided to prevent damaging the f r u s t u l e s . The b e t t e r p a r t s o f these c l e a n i n g methods were combined and sa m p l e / s l i d e p r e p a r a t i o n was c a r r i e d out u s i n g the f o l l o w i n g method. The f r o z e n samples were allowed to thaw and a small p o r t i o n was removed with a s p a t u l a . Around 100-200mg. of wet sample was found to provide s u f f i c i e n t diatoms. The sample weight was determined by the d i f f e r e n c e between the o r i g i n a l sample weight and t h a t with the diatom subsample removed. The sample was p l a c e d i n a c l e a n t e s t - t u b e and 10-20 ml. of d i s t i l l e d water were added. The suspension was shaken by hand and allowed to s e t t l e f o r 6 hours. The supernatant was then removed u s i n g a m i c r o - p i p e t t e a t t a c h e d to a V e n t u r i s u c t i o n pump. T h i s procedure was repeated twice i n order to remove most of the s a l t from the samples. The r i n s e d sample was then d i l u t e d with 10 ml. of Primary c l e a n i n g s o l u t i o n , c o n s i s t i n g o f 100 ml. hydrogen peroxide, 100 ml. g l a c i a l a c e t i c a c i d and 20 g. of sodium hexametaphosphate made up to 500ml. with d i s t i l l e d water. The sample was shaken and allowed to s e t t l e u n t i l b u bbling stopped. T h i s u s u a l l y o c c u r r e d i n 24hrs. but the sample was l e f t f o r another 6hrs. to allow f r u s t u l e s suspended by the bubbles to s e t t l e . The c l e a n i n g s o l u t i o n was then removed and the sample r i n s e d with d i s t i l l e d water. 197 F u r t h e r o r g a n i c removal and ^ b l e a c h i n g ' of the f r u s t u l e s was done by adding 2 ml. of a s o l u t i o n c o n t a i n i n g 6mg./ml. potassium p e r s u l p h a t e with the samples being placed i n an oven o v e r n i g h t a t 70 °C. The samples were c o o l e d to room temperature, allowed to s e t t l e and the s o l u t i o n removed. They were then r i n s e d once more with d i s t i l l e d water and then f i n a l l y d i l u t e d to 13.5 ml.(the volume of the storage v i a l s used) with d i s t i l l e d water c o n t a i n i n g a few drops of Photoflow. The Photoflow a c t s as a whetting agent and f a c i l i t a t e s the d i s p e r s a l of the f r u s t u l e s on the cover s l i p p r i o r to mounting (C. Sancetta. pers.comm.) The c l e a n i n g tubes used were w e l l washed i n 10% HCl between uses and r i n s e d with d i s t i l l e d water before use. Pure water r i n s e s were checked on o c c a s i o n under the microscope f o r t r a n s f e r e n c e of f r u s t u l e s between samples and no s i g n i f i c a n t contamination was observed. Three s l i d e s were made of each sample: a smear s l i d e of the raw sediment and two d i l u t i o n s of the cleaned m a t e r i a l . The f i r s t d i l u t i o n was 500ul. of the 13.5ml; the second d i l u t i o n was 250ul. of the sample together with 250ul. of d i s t i l l e d water. The 250ul. d i l u t i o n proved to be much e a s i e r to count s i n c e 500ul. o f t e n c o n t a i n e d too many f r u s t u l e s . The d i l u t e d subsamples were p i p e t t e d onto an 18x18 mm c o v e r s l i p and allowed to dry i n a i r but p r o t e c t e d from dust. 198 Once the d i l u t i o n s had d r i e d on the c o v e r s l i p a drop of Hyrax mounting medium (RI=1.63) was p l a c e d i n the ce n t e r of the s l i p and spread out by h e a t i n g the s l i p over a h o t - p l a t e a t low temperature. The c o v e r s l i p was p i c k e d up with a heated microscope s l i d e , t i l t e d and tapped to remove trapped a i r bubbles and allowed to c o o l . Counting of the clea n e d m a t e r i a l was done on a pha s e - c o n t r a s t microscope a t 400x m a g n i f i c a t i o n . ( F i e l d o f view =0.46mm. diameter) A l l complete f r u s t u l e s w i t h i n the f i e l d o f view were counted on t r a n s e c t s i n both the x and y d i r e c t i o n s over the c o v e r s l i p . A minimum of 400 c e l l s were counted; i f t h i s number was exceeded i n the middle of a t r a n s e c t then the t r a n s e c t was completed. Counting 400 c e l l s g i v e s c o u n t i n g s t a t i s t i c s o f ±10% (Lund e t al., 1958). The r e s u l t s o f the cou n t i n g performed on the cleaned m a t e r i a l are presented i n Table E.I. Counting was con c e n t r a t e d on c e r t a i n groups, s i n c e the o b j e c t was simply to e s t a b l i s h s e a s o n a l i t y i n the top of CPIV. However, many of the diatom groups were a l s o i d e n t i f i e d to genus, and i n many cases to s p e c i e s , l e v e l . A s p e c i e s l i s t i s g i v e n i n t a b l e E . I I . Table E.2. Species l i s t o f diatoms observed i n core C P I V -A c t i n o c v c l u s c u r v a t u l u s J a n i s h Actinoptvchus s e n a r i u s Ehrenberg Actinoptvchus undulatus ( B a i l e y ) R a l f s A s t e r i o n e l l a q l a c i a l i s Castracane Asteromohalus h e p t a c t i s (Brebisson) R a l f s Chaetoceros a f f i n i s Lauder C. convolutus Castracane or C. c o n c a v i c o r n i s Mangin C. d e c i o i e n s Cleve 199 C. d e b i l i s Cleve C. diadema (Ehrenberg) Gran C.didvmus Ehrenberg C. r a d i c a n s Schutt C . s i m i l i s Cleve C. subsecundus (Grunow) Hustedt C. v a n h e u r k i i Gran C o s c l n o d i s c u s qjqas Ehrenberg C o s c i n o d i s c u s r a d i a t u s Ehrenberg Ditvlum b r i q h t w e l l i i (West) Grunow M i n i d i s c u s S P P . Maybe M . t r i o c u l a t u s or M. c h i l e n s i s O d o n t e l l a a u r i t a (Lyngbye) Agardh P a r a l i a s u l c a t a (Ehrenberg) Cleve Pleurosigma strigosum or Pleurosigma angulatum Pseudoeunotia d o l i o l u s ( W a l l i c h ) Grunow? Raphoneis s u r i r e l l a R h i z o s o l e n i a s e t i g e r a B r i g h t w e l l Skeletonema costatum ( G r e v i l l e ) Cleve Stephanopvxis t u r r i s ( G r e v i l l e and A r n o t t ) R a l f s Thalassionema n i t z s c h i o d e s (Grunow) P e r a g a l l o T h a l a s s i o s i r a a e s t i v a l i s Gran T. e c c e n t r i c a (Ehrenberg) Cleve T. g r a v i d a Cleve T. n o r d e n s k o e l d i i Cleve T. p a c i f i c a Gran and Angst T h a l a s s i o t h r i x l o n g i i s s i m a Cleve and Grunow T h a l a s s i o t h r i x f r a u e n f e l d i i Grunow Diatoms from the genuses: Cocconeis. C v c l o t e l l a .  Grammatophora. N a v i c u l a and N i t z s c h i a were a l s o r e c o g n i s e d but not i d e n t i f i e d to s p e c i e s . SILICOFALGELLATES. Distephanus speculum Ehrenberg EBRIDIANS. E b r i a t r i p a r t i t a (Schumberg) Lemmermann. REFERENCES USED TO IDENTIFIY SPECIES. 1: Cupp E.E 1943 Marine Plankton diatoms of the west c o a s t of North America. B u l l . S c r i o o s I n s t . Ocgy.  Tech. Ser. 5.pp 1-248. 2: Gran H.H and Angst E.C 1931 Plankton Diatoms of Puget Sound. Pub.Puqet Sound Mar. B i o l . Stn. 7. pp 417-519. 200 3: Hendey N.I 1964 An I n t r o d u c t o r y Account of the s m a l l e r Algae of B r i t i s h C o a s t a l Waters. B a c i l l a r i o p h y c e a e (Diatoms). H.M.S.O London. 317p. 4: Hustedt F 1927-1966 Die K i e s e l a l g e n Deutschlands, O e s t e r r e i c h s und der Schweiz. In; Kryptogamen- F l o r a 7. P a r t 1.2.3. (ed. L. Rabenhorst) 1927- 1966. 5: Shim J.H 1976 D i s t r i b u t i o n and Taxonomy of p l a n k t o n i c marine diatoms i n the S t r a i t of Georgia. Ph.D t h e s i s U.B.C Vancouver. 248p. 6: R o e l o f s A.K 1983 The D i s t r i b u t i o n of Diatoms i n the s u r f a c e sediments of B r i t i s h Columbia I n l e t s . Ph.D  t h e s i s U.B.C Vancouver. 253p. 

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