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Physical controls on the distribution of contaminants on Sturgeon Bank, Fraser River Delta, British Columbia Feeney, Tracey Dawn 1995

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PHYSICAL CONTROLS ON THE DISTRIBUTION OF CONTAMINANTS ON STURGEON BANK, FRASER RIVER DELTA, BRITISH COLUMBIA by Tracey Dawn Feeney B.Sc. University of British Columbia, 1989 A THESIS SUBMHTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES Oceanography We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA December, 1995 © TRACEY FEENEY, 1995 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 scholariy 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 The University of British Columbia Vancouver, Canada DE-6 (2/88) A B S T R A C T The physical controls on the distribution of contaminants on the environmentally sensitive Sturgeon Bank tidal flat of the Fraser River delta is being studied to define the locations of erosion and deposition, and migration pathways of sediment and associated contaminants. Sediment erodibility was measured at 10 sites using an insitu benthic annular flume called the Sea Carousel. At each site, InterOcean S4 current meters were also deployed for one month to determine current speed and direction, and suspended sediment concentrations were measured twice weekly for 2 months. Grain size analysis was performed on sediments collected from these 10 sites and an additional 56 sites. The 56 sites were also analyzed for major and minor element composition. Sea Carousel data reveal that sediments on the inner bank are not suspended by the current velocities measured at these stations due to surface cohesion in fine-grained material. Unlike the inner bank, sediments on the outer bank are suspended by wave-induced currents and in some cases tidal currents, especially in the fine sand-dominated sediments on the outer southern area of the bank. Eroded sediments from this area appear to be transported shoreward. Current meter data reveal that currents are variable both spatially and temporally on the bank. In general, flow is bidirectional with flooding currents on the outer bank (seaward) having higher average velocities. Currents on the inner bank (shoreward) show no consistent orientation of peak velocities. Suspended sediment data show an increase in concentration shoreward and a marked increase as wave height increases. Geochemical results reveal that surface sediments on Sturgeon Bank show very little contamination in Pb, Cu, Zn, Ni, Cr and V. The distribution of these elements on Sturgeon Bank is controlled primarily by sediment texture and physical controls on sediment transport. The coarse-grained nature and ii relatively low clay content of sediments on the bank result in a decreased accumulation of minor elements. Cobalt concentrations are unusually high in some surface sediments, a result not explainable in the scope of this study. Results indicate that contaminated sediments known to have been deposited in the past on Sturgeon Bank due to sewage discharge are not present at the surface. This probably reflects more recent deposition of less contaminated sediments transported from the Fraser River distributaries and/or deposition of sediments resuspended from the outer bank which have been transported shoreward. iii TABLE OF CONTENTS Page No. ABSTRACT ii LIST OF FIGURES vii ACKNOWLEDGEMENTS xvi Chapter 1. INTRODUCTION 1.1. The problem with the intertidal 1 1.2. Regional Setting 2 1.3. Sturgeon Bank study area 5 1.4. Sewage effluent discharge history 9 1.5. Project Overview 11 Chapter 2. ERODIBILITY MEASUREMENTS 2.1. The Sea Carousel and field sampling 15 2.2. Data reduction 16 2.3. Results and Discussion 19 2.3.1. Cohesive sediments 20 2.3.1.1. Erosion rates 20 2.3.1.2. Erosion thresholds 21 2.3.2. Non-cohesive sediments 25 2.3.3. Sediment transport rates 33 Chapter 3. PHYSICAL OCEANOGRAPHIC PROPERTIES 3.1. The S4 current meters and field sampling 45 3.2. Data reduction 46 3.3. Results and discussion 47 3.3.1. 10° increment-averaged velocity and directional data 47 3.3.2. One-minute-averaged velocity data 53 3.3.3. High-frequency velocity fluctuations (waves) 54 3.3.3.1. Erosional capabilities of currents on Sturgeon Bank 55 3.3.4. Temperature and salinity variations 60 Chapter 4. SUSPENDED SEDIMENT 4.1. Field sampling 62 4.2. Analytical techniques 63 4.3. Results and discussion 64 4.3.1. Shoreward increase in suspended sediment concentration 64 4.3.2. Decreasing suspended sediment throughout sampling period 66 iv 4.3.3. Increase in suspended sediment concentration due to wind and waves 68 4.3.4. Limitations of suspended sediment concentration data 69 Chapter 5. GRAIN SIZE ANALYSIS 5.1. Field sampling 71 5.2. Analytical techniques 71 5.3. Results and discussion 73 5.3.1. Sediment grain size 73 5.3.2. Sediment sorting 76 5.3.3. Grain size and sorting controls on erodibility 80 5.3.4. Sediment grain size variability 81 Chapter 6. SEDIMENT GEOCHEMISTRY 6.1. Field sampling 82 6.2. Analytical techniques 82 6.3. Results and Discussion 83 6.3.1. Controlling factors on the composition of sediments 83 6.3.2. Major elements 86 6.3.2.1. Aluminum 86 6.3.2.2. Silicon 86 6.3.2.3. Titanium 90 6.3.2.4. Iron 94 6.3.3. Carbon and Nitrogen 101 6.3.4. Minor elements 103 6.3.4.1. Cobalt 106 6.3.4.2. Chromium 110 6.3.4.3. Nickel 114 6.3.4.4. Vanadium 118 6.3.4.5. Manganese 122 6.3.4.6. Copper 124 6.3.4.7. Zinc 128 6.3.4.8. Lead 131 6.3.4.9. Zirconium 135 6.3.5. Sediment geochemical variability 139 6.3.6. Geochemical summary of Sturgeon Bank sediments 144 Chapter 7. SUMMARY AND CONCLUSIONS 7.2. Summary 148 7.3. Conclusions 152 7.2.1. Recommendations 152 REFERENCES 154 v APPENDIX I: GPS bathymetric survey description 163 APPENDKII: Geographical stations locations on Sturgeon Bank 169 APPENDIX HI: Time series plots for Sea Carousel erodibility data 171 APPENDLX IV: Physical Oceanographic data on Sturgeon Bank 182 rv-l Station SI 182 rV-2 Station S2 189 IV-3 Station S3 196 rV-4 Station S4 203 rV-5 Station S5 219 IV-6 Station S6 224 IV-7 Station SI 1 232 rV-8 Stations 12 236 rV-9 Stations 13 246 IV-10 Stations 14 255 APPENDLX V: Suspended sediment results 262 APPENDLX VI: Results and statistical analyses of grain size measurements VI-1 Statistical analyses 272 VI- 2 Grain size results 274 APPENDLX VH: Sediment geochemistry - analytical description Vn-1 Major element analysis 276 VII- 2 Minor element analysis 277 VII-3 X-ray fluorescence spectrometry 277 VII-4 Total carbon and nitrogen analysis 278 VH-5 Inorganic carbon analysis 279 VII-6 Major element results 282 VII-7 Minor element results 283/284 VII-8 XRF instrument settings VII-8a Major elements 285 VH-8b Minor elements 285 VII-9 Accuracy of XRF analyses VR-9a Major elements 286 VII-9b Minor elements 287 VII-10 Analytical precision of XRF analyses Vll-lOa Major elements 288 VH-lOb Minor elements 289 VH-11 Analytical precision of gas chromatography/thermal conductivity analyses .. 290 VH-12 Analytical precision of coulometry analyses 291 VH-13 Carbon and nitrogen results 292 vi LIST OF FIGURES Page No. 1. The Fraser River delta, British Columbia 3 2. Elevation map of Sturgeon Bank 7 3. Three-dimensional perspective of Sturgeon Bank with overlayed elevation contours . . . . 8 4. Sturgeon Bank study area and station locations 13 5. Sediment strength with depth at station 1 22 6. Sediment strength with depth at station 2 23 7. Sediment strength with depth at station 3 24 8. Sediment strength with depth at station 13 26 9. Sediment strength with depth at station 14 27 10. Suspended sediment concentration (Upper OBS minus ambient OBS) versus applied bed shear stress at station 4 28 11. Suspended sediment concentration (Upper OBS minus ambient OBS) versus applied bed shear stress at station 5 29 12. Suspended sediment concentration (Upper OBS minus ambient OBS) versus applied bed shear stress at station 6 30 13. Suspended sediment concentration (Upper OBS minus ambient OBS) versus applied bed shear stress at station 11 31 14. Suspended sediment concentration (Upper OBS minus ambient OBS) versus applied bed shear stress at station 12 32 15. Suspended sediment transport rate versus applied bed shear stress at station 34 16. Suspended sediment transport rate versus applied bed shear stress at station 2 . . . . . . . 35 17. Suspended sediment transport rate versus applied bed shear stress at station 3 36 vii 18. Suspended sediment transport rate versus applied bed shear stress at station 13 37 19. Suspended sediment transport rate versus applied bed shear stress at station 14 39 20. Suspended sediment transport rate versus applied bed shear stress at station 4 40 21. Suspended sediment transport rate versus applied bed shear stress at station 5 41 22. Suspended sediment transport rate versus applied bed shear stress at station 6 42 23. Suspended sediment transport rate versus applied bed shear stress at station 11 43 24. Suspended sediment transport rate versus applied bed shear stress at station 12 44 25. Current direction plots for 10° averaged increments 48 26. Current speed plots for 10° averaged increments a-e) Stations 1, 2, 3,4 (May), and 4 (June) 50 f-k) Stations 5, 6, 11, 12, 13, and 14 51 27. Highest current velocities recorded at each station through one month S4 deployments a-e) Stations 1, 2, 3, 13, and 14 56 f-k) Stations 4 (May, 4 (June), 5, 6, 11, and 12 57 28. Suspended sediment concentrations on Sturgeon Bank 65 29. Fraser River discharge rates for May/June, 1993 67 30. Ternary diagram indicating percent sand/silt/clay for sediments on Sturgeon Bank . . . 74 31. Sediment grain size on Sturgeon Bank using Wentworth classification 75 32. Degree of sorting in sediments on Sturgeon Bank 77 33. Percent mud versus percent sorting and grain size (in phi units) 79 34. Areal distribution of aluminum content on Sturgeon Bank 87 35. Aluminum content versus grain size 88 36. Areal distribution of silicon content on Sturgeon Bank 89 37. Silica content versus grain size 91 viii 38. Areal distribution of Si/Al on Sturgeon Bank 92 39. Areal distribution of titanium content on Sturgeon Bank 93 40. Areal distribution of Ti/Al on Sturgeon Bank 95 41. a) Titanium content versus grain size 96 b) Titanium content versus iron content 96 42. Areal distribution of iron content on Sturgeon Bank 98 43. Areal distribution of Fe/Al on Sturgeon Bank 99 44. a) Iron content versus grain size 100 b) Iron content versus magnesium content 100 45. Areal distribution of organic carbon on Sturgeon Bank 102 46. C o r g content versus grain size 104 47. Areal distribution of Corg/N on Sturgeon Bank 105 48. Areal distribution of cobalt content on Sturgeon Bank 107 49. Areal distribution of Co/Al on Sturgeon Bank 108 50. a) Cobalt content versus grain size 109 b) Cobalt content versus magnesium content 109 c) Cobalt content versus iron content 109 d) Cobalt content versus C o r g content 109 51. Areal distribution of chromium content on Sturgeon Bank Ill 52. Areal distribution of Cr/Al on Sturgeon Bank 112 53. a) Chromium content versus grain size 113 b) Chromium content versus magnesium content 113 c) Chromium content versus iron content 113 54. Areal distribution of nickel content on Sturgeon Bank 115 55. Areal distribution of Ni/Al on Sturgeon Bank 116 ix 56. a) Nickel content versus grain size 117 b) Nickel content versus magnesium content 117 c) Nickel content versus iron content 117 d) Nickel content versus C o r g content 117 57. Areal distribution of vanadium content on Sturgeon Bank 119 58. Areal distribution of V/Al on Sturgeon Bank 120 59. a) Vanadium content versus grain size 121 b) Vanadium content versus iron content 121 60. Areal distribution of manganese content on Sturgeon Bank 123 61. Areal distribution of Mn/Al on Sturgeon Bank 125 62. a) Manganese content versus grain size 126 b) Manganese content versus magnesium content 126 c) Manganese content versus iron content 126 63. Areal distribution of copper content on Sturgeon Bank 127 64. Areal distribution of Cu/Al on Sturgeon Bank 129 65. a) Copper content versus grain size 130 b) Copper content versus iron content 130 c) Copper content versus lead content 130 d) Copper content versus zinc content 130 66. Areal distribution of zinc content on Sturgeon Bank 132 67. Areal distribution of Zn/Al on Sturgeon Bank 133 68. a) Zinc content versus grain size 134 b) Zinc content versus iron content 134 c) Zinc content versus lead content 134 69. Areal distribution of lead content on Sturgeon Bank 136 70. Areal distribution of Pb/Al on Sturgeon Bank 137 71. Lead content versus grain size 138 x 72. Areal distribution of zirconium content on Sturgeon Bank 140 73. Areal distribution of Zr/Al on Sturgeon Bank 141 74. Zirconium content versus grain size 142 75. Principal components analysis using Pb, Zn, Cu, Ni, Co, Cr, and Ti02 147 76. Sturgeon Bank contours constructed from GPS kinematic survey data 166 77. Three-dimensional perspective of Sturgeon Bank 167 78. Approximate channel locations constructed using GPS kinematic survey data 168 79. Time series plots Sea Carousel Results at station 1 a) Current speed versus time 172 b) Suspended sediment concentration versus time 172 c) Erosion rate versus time 172 80. Time series plots Sea Carousel Results at station 2 a) Current speed versus time 173 b) Suspended sediment concentration versus time 173 c) Erosion rate versus time 173 81. Time series plots Sea Carousel Results at station 3 a) Current speed versus time 174 b) Suspended sediment concentration versus time 174 c) Erosion rate versus time 174 82. Time series plots Sea Carousel Results at station 13 a) Current speed versus time 175 b) Suspended sediment concentration versus time 175 c) Erosion rate versus time 175 83. Time series plots Sea Carousel Results at station 14 a) Current speed versus time 176 b) Suspended sediment concentration versus time 176 c) Erosion rate versus time 176 84. Time series plots Sea Carousel Results at station 4 a) Current speed versus time 177 b) Suspended sediment concentration versus time 177 xi 85. Time series plots Sea Carousel Results at station 5 a) Current speed versus time 178 b) Suspended sediment concentration versus time 178 86. Time series plots Sea Carousel Results at station 6 a) Current speed versus time 179 b) Suspended sediment concentration versus time 179 87. Time series plots Sea Carousel Results at station 11 a) Current speed versus time 180 b) Suspended sediment concentration versus time 180 88. Time series plots Sea Carousel Results at station 12 a) Current speed versus time 181 b) Suspended sediment concentration versus time 181 89. One-minute-averaged velocities for the month of June, 1993 at station 1 183 90. Wave particle velocities for the June 21, 1900-2200 h sampling interval at station 1 184 91. Average speed and direction plotted over 10°-averaged increments at station 1 . . . . . 185 92. Water temperature variations for the month of June, 1993 at station 1 187 93. Salinity variations for the month of June, 1993 at station 1 188 94. One-minute-averaged velocities for the month of May, 1993 at station 2 190 95. Wave particle velocities for the May 11, 2000 to May 12, 0200 h sampling interval at station 2 191 96. Average speed and direction plotted over 10°-averaged increments at station 2 192 97. Water temperature variations for the month of May, 1993 at station 2 194 98. Salinity variations for the month of May, 1993 at station 2 195 99. One-minute-averaged velocities for the month of June, 1993 at station 3 197 100. Wave particle velocities for the June 6, 1700 to June 7, 0900 h sampling interval at station 3 198 xii 101. Average speed and direction plotted over 10°-averaged increments at station 3 . . . . 200 102. Water temperature variations for the month of June, 1993 at station 3 201 103. Salinity variations for the month of June, 1993 at station 3 202 104. One-minute-averaged velocities for the month of May, 1993 at station 4 204 105. One-minute-averaged velocities for the month of June, 1993 at station 4 205 106. Wave particle velocities for the May 11, 2000 to May 12, 1100 h sampling interval at station 4 207 107. Wave particle velocities for the June 4, 1500 to June 5, 0800 h sampling interval at station 4 208 108. Average speed and direction plotted over 10°-averaged increments at station 4 in May, 1993 209 109. Average speed and direction plotted over 10°-averaged increments at station 4 in June, 1993 210 110. Water temperature variations for the month of May, 1993 at station 4 212 111. Water temperature variations for the month of June, 1993 at station 4 213 112. Salinity variations for the month of May, 1993 at station 4 214 113. Salinity variations for the month of June, 1993 at station 4 216 114. Depth variations for the month of May, 1993 at station 4 217 115. Depth variations for the month of June, 1993 at station 4 218 116. One-minute-averaged velocities for the month of June, 1993 at station 5 220 117. Wave particle velocities for the June 6,2300 to June 7,1000 h sampling interval at station 5 221 118. Wave particle velocities for the June 19, 0400-0800 h sampling interval at station 5 222 119. Average speed and direction plotted over 10°-averaged increments at station 5 . . . . 223 xiii 120. Water temperature variations for the month of June, 1993 at station 5 225 121. Salinity variations for the month of June, 1993 at station 5 226 122. One-minute-averaged velocities for the month of May, 1993 at station 6 227 123. Wave particle velocities for the May 11,1900 to May 12,1300 h sampling interval at station 6 229 124. Average speed and direction plotted over 10°-averaged increments at station 6 . . . . 230 125. Water temperature variations for the month of May, 1993 at station 6 231 126. Salinity variations for the month of May, 1993 at station 6 232 127. One-minute-averaged velocities for the month of June, 1993 at station 11 234 128. Wave particle velocities for the June 4, 1400 to June 5, 0900 h sampling interval at station 11 235 129. Average speed and direction plotted over 10°-averaged increments at station 11 . . . 237 130. Water temperature variations for the month of June, 1993 at station 11 238 131. Salinity variations for the month of June, 1993 at station 11 239 132. One-minute-averaged velocities for the month of May, 1993 at station 12 240 133. Wave particle velocities for the May 11, 1900 to May 12, 0400 h sampling interval at station 12 242 134. Wave particle velocities for the May 12,0600-1300 h sampling interval at station 12 243 135. Wave particle velocities for the May 23, 0500-0900 h sampling interval at station 12 244 136. Average speed and direction plotted over 10°-averaged increments at station 12 . . . 245 137. Water temperature variations for the month of May, 1993 at station 12 247 138. Salinity variations for the month of May, 1993 at station 12 248 xiv 139. One-minute-averaged velocities for the month of June, 1993 at station 13 249 140. Wave particle velocities for the June 6, 2200 to June 7,0900 h sampling interval at station 13 251 141. Average speed and direction plotted over 10°-averaged increments at station 13 . . . 252 142. Water temperature variations for the month of June, 1993 at station 13 253 143. Salinity variations for the month of June, 1993 at station 13 254 144. One-minute-averaged velocities for the month of May, 1993 at station 14 256 145. Wave particle velocities for the May 11, 2100 to May 12, 0200 h sampling interval at station 14 257 146. Average speed and direction plotted over 10°-averaged increments at station 14 . . . 259 147. Water temperature variations for the month of May, 1993 at station 14 260 148. Salinity variations for the month of May, 1993 at station 14 261 xv A C K N O W L E D G E M E N T S I would like to express my sincere thanks to my supervisor, Dr. Paul LeBlond for never putting any pressure on me in one of the most difficult years of my life. Your words of wisdom and positive outlook were always appreciated. Dr. John Luternauer and the entire staff of the Cordilleran Division of the Geological Survey of Canada provided funding and many hours of discussion. Dr. Luternauer was a master of finding more things for me to think about. Dr. Carl Amos, from the Atlantic Geoscience Centre, provided the impetus for this study and was patient in all of the hundreds of phone conversation we had while I learned about sediment transport. Dr. Tom Pedersen and Dr. Steve Calvert taught me a great deal about a subject I was relatively unfamiliar with - geochemistry. Dr. Steve Pond graciously loaned me five S4 current metres and allowed me to deploy them in an area of high risk. If not for his rigorous testing, the data may never have been collected in such a difficult environment. A special thanks goes to the members of the Canadian Coast Guard hovercraft search and rescue unit who made sampling on the delta much more enjoyable; they were always cheerful, patient and their skill was greatly appreciated. Dr. Peter Mustard was always supportive, helpful and spent many hours with me reducing data and writing programs. I would like to thank the many people who volunteered to collect mud and water samples over the years of this study; despite the ride in the hovercraft, it was long and tedious work at times. Finally I would like to thank my friends and family, especially my sister, Heather, who put up with sections of my thesis strewn all over the apartment and my untidiness in those last few weeks, and Paul who always made me feel that I could do it. xvi Chapter 1. INTRODUCTION 1.1. THE PROBLEM WITH THE INTERTIDAL The study of sediment dynamics in the marine environment locates areas of erosion, deposition, and pathways of sediment migration. This allows determination of the stability of the environment and the pathways of contaminants associated with these sediments. Intertidal zones are dynamic systems with physical processes such as waves, tides and river runoff contributing to their ever-changing morphology. To understand the sediment dynamics associated with the intertidal environment, a knowledge of the physical parameters and processes at work is required. Conventional field programs conducted on land or at sea must be redesigned for intertidal studies to maximize the quality of information. Data collection is difficult because access by boat is limited by shallow water and access by foot is limited by harsh environments. Instruments commonly used at sea are not designed for sampling while exposed to air, and instruments commonly used on land are not designed for sampling while inundated for several hours. Other unusual considerations include boundary conditions such as the shore and manmade structures, shifting tidal channels, tides, seasonal river discharge variations and many others. The presence of contaminants from natural and anthropogenic sources complicates the problem even more. The fate of these contaminants is further complicated by the influence from the mineralogy, grain size and organic content of the sediments and the physical processes which control their deposition. It is for these reasons that the grey area between the land and the sea known as the "intertidal" has often been avoided when research is undertaken. The Fraser River in southwestern British Columbia, has historically been an important 1 transport route and fishery. The port city of Vancouver and the Lower Mainland, built both on and adjacent to the Fraser River delta, is the second largest city in Canada. The rapid expansion of Vancouver increases the impact from industry, agriculture, sewage, and channel confinement on the Fraser River. The importance of intertidal areas to fish and wildlife have only recently been recognized and, although not yet completely understood, studies are being actively pursued to determine the extent of human influence and the impacts which we have had on the organisms that use both the river and the intertidal as required habitats. 1.2. R E G I O N A L S E T T I N G The Fraser River is more than 1400 km in length, drains an area of approximately 230,000 km 2 and enters the ocean in southern British Columbia adjacent to the city of Vancouver, Canada. In its upper reaches, the Fraser River drops 1 km in elevation in 100 km, but over the next 900 km, to the town of Hope, it levels out to more moderate gradients (Milliman, 1980). Downstream from Hope, the river becomes more mature, passing through alluvial flood plains for 200 km until it reaches its terminus at the Strait of Georgia, forming the Fraser River delta. At New Westminster, approximately 25 km upstream from the mouth, the river bifurcates into the North Arm and the Main Arm (Figure 1). The North Arm, which carries -16% of the total river discharge, bifurcates again at Richmond where -30% of the flow (-5% of the total Fraser River flow) exits via the Middle Arm while the remaining 70% (9% of the total Fraser River flow) exits via the North Arm (Luternauer and Murray, 1973). The Fraser River distributary channels flow through an active deltaic system which includes marshes, intertidal sand and mud flats, and foreslope sediments. Two large intertidal flats, Roberts and Sturgeon Bank, lie on the 2 Figure 1: The Fraser River delta, British Columbia. Colored section outlines Sturgeon Bank study area. 3 deltas western edge (Figure 1). The mean discharge of the Fraser River (measured at Hope) is 3,400 m3/s (McLean and Church, 1986); however flows in the late spring and early summer due to snowmelt average up to 10,000 m3/s (McLean and Church, 1986; Milliman, 1980), and flows in the late fall to early spring average 1500 m3/s (Milliman, 1980). The Fraser transports an average of 20 X 106 m3 of sediment annually with 80% of the sediment load being discharged in the spring freshet. It has been presumed that only 3-9% of the total sediment load in the Fraser River enters the North Arm (Church et al., 1990). The sediment load consists primarily of very coarse silt and sand with an average of 35% of the suspended sediment transported comprising sand (McLean and Tassone, 1991). The high sand content is probably related to the coarse nature of the Pleistocene glacial deposits which form a major Fraser River sediment source (Pharo, 1972; Armstrong, 1956), the seasonality of the river flow and the fact that the river is not dammed at any point. Mathews and Shepard (1962) reported that the delta in the region of the Main Arm advances at a rate of -2.3 m per year at the low water mark. However, recent bathymetric measurements suggest that the slope off Sturgeon Bank is stable, whereas the southernmost portion of Roberts Bank is retreating (Luternauer and Murray, 1973; Luternauer, 1975). The Fraser River delta is Holocene in age, formed since the end of the last glaciation 11,000 - 13,000 years BP (Clague et al., 1983) and is 975 km2 in area (Mathews and Shepard, 1962). The delta deposits, which overlie late Pleistocene till, have an average thickness of 110 m (Johnston, 1921; Mathews and Shepard, 1962). Tides in the Strait of Georgia are mixed semi-diurnal with mean tidal ranges over the 4 delta slope of 2.7 m and over the tidal flats 2.6 m (Canadian Hydrographic Service, 1972; Thomson, 1977). The average range for spring tides over the seaward edge of the delta is 4.7 m, however extreme tides can reach 5.4 m (Canadian Hydrographic Service, 1972). Maximum significant wave heights in the Strait of Georgia are approximately 1.5 m and average heights are approximately 0.6 m (Hoos and Packman, 1974). Based on these values, the most probable maximum waves reaching the delta foreshore would be 2.9 m (Thomson, 1977). During periods of low river discharge and spring tides mixing is enhanced and the estuary is classified as moderately stratified (Hodgins et al., 1977). During high river discharges, mixing is restricted and the estuary is classified as a salt-wedge system (Kostaschuk et al., 1989). Waves generated by wind from the NW have the longest fetch (>100 km) and therefore presumably are the largest; contributing the most to wave-related processes on the delta-front. Wind waves breaking tangentially to the delta slope and breaking internal gravity waves may contribute to longshore drift of sediment and suspended material along the delta-front with flows reaching 50 cm/s (Thomson, 1975). Surface currents over the foreslope flow northward at 0.3-0.5 m/s (Tabata et al., 1971) and a general northward flow of fresh turbid water from the Main Arm across Sturgeon Bank has been observed (Tabata, 1972). Medley (1978) suggests that waves do not break on the flats but dissipate their energy across the bank. 1.3. S T U R G E O N B A N K S T U D Y A R E A Sturgeon Bank is situated on the western edge of the Fraser River delta between the Main Arm and the North Arm of the Fraser River (Figure 1). It is an intertidal sand and mudflat approximately 83 km2 in area. Sturgeon Bank is 6 km wide on average and slopes gently 5 westwards towards the Strait of Georgia at an angle of 0.08°. The southern portion of Surgeon Bank is complicated by the presence of active drainage channels draining the adjacent marsh. A detailed bathymetric map of the area was constructed using a Global Positioning System (GPS) survey which employed two geodetic quality GPS receivers. Contours of Sturgeon Bank elevations were developed (Figure 2) using the Geographical Information System (GIS) Arc/Info program and a three-dimensional perspective was created using the contours (Figure 3). Details of the GPS survey can be found in Aitken and Feeney (1994) and Feeney (1994) and a general description of the survey is provided in Appendix I. The tidal flats are bioturbated and pelletized which is the result of a diverse invertebrate infauna dominated by polychaete worms (Manayunkia aestuaria. Amphicteis sp., Eteone longa, Pygospio elegans, Capitella capitata. hemipodus borealis), bivalves (Macoma balthica. Macoma inconspicua. Mva arenaria. Cryptomya californica). amphipods (Corophium salmonis, Amphithoe humeralis"), isopods (Gnorimosphaeroma lutra and Argeia pugettensis) and decapods (Callianassa californiensis), plus oligochaeta, nematode worms and harpacticoid copepods (B.C. Research, 1977; Bawden et al, 1973; Otte and Levings, 1975; Levings et al., 1983; Harrison, 1981). In addition, twenty-seven species of fish, including commercial species such as salmon, have been reported on Sturgeon Bank (Birtwell et al., 1983). The shoreline of Sturgeon Bank is bordered by a marsh, 3.5 m above chart datum, composed primarily of sedges (Carex sp.) and bulrushes (Scirpus sp.) (B.C. Research, 1975). Benthic macrophytes include Ulva lactuca and Entomoropha sp. and their abundance suggests an increased nutrient concentration (Hoos and Packman, 1974). Benthic microalgae (primarily diatoms) on top of the sediment or within the first centimetre suggests that benthic primary 6 Figure 2: Elevation map of Sturgeon Bank generated from GPS kinematic survey 7 8 productivity is considerable based on estimates of chlorophyll a concentrations (Harrison, 1981). The Sturgeon Bank region has been severely altered by the construction of jetties, the disposal of dredge spoil on the inner flats and the disposal of primary treated sewage effluent from the Iona sewage treatment plant (Figure 4). Jetty construction included the Steveston jetty, North Arm jetty, Iona jetty, and the airport jetty. Prior to 1959, the McDonald Arm of the Fraser River was permitted to discharge onto Sturgeon Bank (similar to the Middle Arm); however at that time, a causeway which blocked this confluence was built to allow access to Iona Island. In addition, the bank has been altered by high metal values which have been observed in both sediments (Benedict et al., 1973; Hall and Fletcher, 1974; Hall et al., 1974) and benthic organisms (Parsons et al., 1973; Bawden et al., 1973) due to the discharge of metal-rich sewage on Sturgeon Bank (Hall et al., 1975). 1.4. SEWAGE EFFLUENT DISCHARGE HISTORY The Iona sewage treatment plant, began operation in 1962 and underwent three expansions prior to 1985. Prior to its opening, a jetty 4.5 km in length was constructed on Sturgeon Bank, spanning almost the entire width of the intertidal area. The jetty was built to control the flow of effluent discharged from the plant to ensure that it did not end up on populated beach areas nearby. From 1962 until 1988 storm and sanitary sewage effluent from the Iona Sewage Treatment Plant was discharged into a shallow dredged channel which ran parallel to the Iona jetty on its south side (Coastline Environmental Services Ltd., 1985). The effluent discharged at this time varied from 376.4 x 103 mVday for average flows between May and October, and 581.4 x 103 m3/day for winter months (Coastline Environmental Services Ltd., 9 1985). Effluent flow rates of less than 942 x 103 mVday were given primary treatment (i.e. screening, grit, scum and grease removal, sedimentation, and chlorination from May 1 to September 30 to reduce bacterial coliform counts during the summer) (Rawn et al., 1953; S&S Consultants, 1983) but flows exceeding this level received little or no treatment (Birtwell et al., 1983). During low tide, the effluent flowed seaward in the channel for almost 7 km. However, during high tide, the channel was essentially ineffective at moving the effluent off the bank and it was dispersed over inner Sturgeon Bank resulting in rapid environmental degradation of the area. The effects of deposition of this sewage-laden particulate matter onto Sturgeon Bank included elevated levels of heavy metals, total organic carbon (TOC), coliform bacteria, and sediment oxygen demand which resulted in numerous fish kills in the area (Birtwell et al., 1983) and impacts on the benthic communities adjacent to the outfall (B.C. Research, 1973, 1975, 1977; McGreer, 1982). In response to this problem a deep-water outfall extension was constructed in 1987 which extended from the end of the existing jetty into the Strait of Georgia, where effluent is now discharged through a diffuser at 107 metres depth on the delta slope. During severe rainstorms overflow effluent is still discharged through the original pipe onto Sturgeon Bank, but this rarely occurs more than once or twice per year (Iona Sewage Treatment Plant operator, pers. comm., 1993). Sewage releases heavy metals such as mercury, cadmium and vanadium (Hall et al., 1974) which can be adsorbed onto sediments and may accumulate in organisms (Parsons et al., 1973). Additional potential pollutants are those discharged from the Fraser River system that may be transported to the tidal flats, including industrial, agricultural and urban runoff. 10 Upon installation of the deep outfall pipe, the Department of Fisheries and Oceans began monitoring the recovery of the area, but had many concerns about the final deposition sites of the contaminated sediments. It was believed that burial of the sediments by recent sedimentation would eventually lead to their withdrawal from the environment. Erosion of these sediments could mean their complete removal, but also could result in resuspension increasing the risk of entrance into the biological food chain, or transport of the contaminated sediments to other important habitats. The need to address these issues provided the impetus for this study. 1.5. P R O J E C T O V E R V I E W Sediments form important habitats for organisms. They are also often either a temporary or permanent sink for metals. Both natural and anthropogenic controls allow metals to accumulate to high levels in some sediments, thus increasing the possibility that they may become incorporated into the biota. Although aquatic organisms require certain trace metals to metabolize, when these metals, and others not used in the metabolic process, are available in excess they may exert toxic effects. Although determining the fate of contaminated sediments on Sturgeon Bank is critical, the processes which control sediment transport are practically unstudied. The main objective of this study was to determine the major processes controlling sediment transport on Sturgeon Bank and relate these processes to the fate of contaminants deposited within them. These objectives were carried out by conducting several analyses: 1) In order to determine the erosional processes sediment erodibility was determined in situ using a benthic field flume; 2) the physical oceanographic processes were determined using in situ measurements of currents; 3) the 11 suspended sediment processes were determined using in situ measurements of suspended sediment concentration; 4) the sediment textural properties were determined by measuring grain size and sorting; 5) the sediment geochemical properties were determined by measuring the major/minor element concentration and organic content permitting the examination of the areal extent of contaminant dispersal on Sturgeon Bank. This study employed innovative data collection techniques in non-traditional sampling environments. Although work on in situ sediment erodibility measurements have been done, these studies are not common and, until now have never been attempted on the Fraser delta. In situ current velocity and directional information and suspended sediment concentration measurements have never been collected on Sturgeon Bank and GPS kinematic surveys to determine intertidal bathymetry have only recently been attempted and never on the Fraser delta. These studies constitute important baseline information that may now be used in future studies. Sample sites were chosen using the air-photo based sediment classification of Medley and Luternauer (1976) (Figure 4). Ten primary stations were used in this study, occupying 3 transects. The density of stations was highest adjacent to the Iona jetty where 6 stations were selected (SI, S2, S3, S4, S5, and S6). Three stations running parallel to the Steveston jetty were chosen (SI 1, SI2, and SI3) and one station adjacent to the Middle Arm was selected (S14). An additional 56 stations on Sturgeon Bank were chosen, including stations north of the Iona jetty, for grain size/sorting measurements and major/minor element analyses. These sites were sampled to provide an areal distribution of grain size, sorting, and contaminant concentrations over the entire area of Sturgeon Bank. The grain size and erodibility results measured at the 10 primary sites were believed to be representative of the results at sites elsewhere on the bank with 12 Figure 4: Sturgeon Bank study area and station locations 13 similar sediment characteristics. However, this was not the case as the variability in measured parameters between stations was large and therefore extrapolation was not realistic, thus not attempted. Results of data collected from the area north of the Iona jetty have been included for reference purposes, however, the focus of this study is centred around the area of Sturgeon Bank between the Iona and Steveston jetties and more specifically the 10 primary stations. Major and minor element concentrations were not determined on sediments collected from the Sea Carousel stations due to an inadequate supply of sediment sampled. Due to the vast amount of data collection required to understand the physical processes and sediment properties of the marsh area on Sturgeon Bank, an independent study would be needed. Therefore the marsh area was not sampled in this study. It is important to note, however, that the marsh may play a significant role in the accumulation of contaminants on Sturgeon Bank. For ease in interpretation, the bank has been divided into three zones in this study, namely northern Sturgeon Bank between the North Arm and Iona jetties, central Sturgeon Bank between Iona jetty and the Middle Arm of the Fraser River, and southern Sturgeon Bank between the Middle Arm and the Steveston jetty. Geographical station locations are listed in Appendix H. Conditions at stations varied from rippled sand to thick mud, the latter making the occupation of some sites impossible by traditional methods. Because of the difficulty in accessing such a large area during successive high tides or low tides and unstable sediment conditions at some stations, a Canadian Coast Guard hovercraft was employed as a sampling vehicle. The hovercraft's manoeuvrability on both land and water allowed access to sampling stations at any time during the tidal cycle quickly and easily. Data collection began in July, 1992 with the majority of sampling occurring in May and June, 1993. 14 Chapter 2. SEDIMENT ERODIBILITY 2.1. THE SEA CAROUSEL AND FIELD SAMPLING An instrument known as the Sea Carousel was deployed at 10 stations on Sturgeon Bank to determine sediment response to currents. The instrument is an annular benthic field flume designed for use in intertidal and sub-tidal settings. The Sea Carousel comprises an annulus, 2 metres in diameter, 0.3 metres high, and 0.15 metres wide, within which flow is induced; an underwater pod containing controllers and battery power for electronic sensors; and a ship-board monitor, computer and power supply. The output voltages from all sensors were digitized and transformed to scientific units on a Campbell Scientific CR10 data logger and stored on a Campbell Scientific SM 192 storage module. The data logger is programmed from the surface using the computer through an RS232 interface. A more detailed description of the Sea Carousel is given in Amos et al. (1992a). A flow is set up via the computer by rotating a mobile lid equipped with 8 paddles within the annulus. The flow is increased at 10 minute intervals up to an azimuthal velocity of 1.0 m/s (Amos et al., 1992b). Vertical and azimuthal current speed is recorded by a Marsh McBirney current meter located in the annulus at a height of 0.25 metres above the bed. Three Optical Backscatter Sensors (OBS) located in the annulus measure the amount of sediment in suspension at each induced current velocity. Two of the sensors are located on the inner wall of the annulus at heights of 0.07 and 0.22 m above the base of the annulus (the seabed), hereby referred to as the lower and upper OBS. The third OBS is located outside the annulus to detect ambient particle concentration. A video camera monitors the seabed through a window in the flume wall. 15 A horizontal skirt situated 0.04 metres above the base of the annulus ensures a standardized penetration of the flume into the seabed. The OBS's give a linear response to particle concentration for mud and sand over a range in concentrations of 0.1 to 50 g/1 (Downing and Beach, 1989). The OBS's are calibrated by analyzing water samples pumped from the annulus through a sampling port 0.2 metres above the skirt for suspended sediment concentration (SSC). The physical properties of the sediment are expected to vary across the tidal flats due to differences in grain size, relative exposure (Anderson and Howell, 1984), and biological influences (Amos et al., 1988; Underwood and Paterson, 1993). The biological influences include benthic diatoms (Grant et al., 1986; Paterson, 1989; Paterson et al., 1990), vegetation, animal tracking, pelletization and bioturbation (Nowell et al., 1981; Jumars et al., 1981). The Sea Carousel was towed to stations SI through S14 (See Figure 4) at high tide on a floating pontoon and the instrument lowered to the seafloor slowly to ensure minimal water and seabed disturbance. This allowed the measurements of the natural, saturated substrate erosional properties in situ. Each station was occupied between July 18 and July 28, 1992. For a detailed description of the study and its results refer to Amos et al. (in prep). 2.2. DATA REDUCTION A time series plot of the vertical and azimuthal current velocities, the three measures of suspended sediment concentration and the erosion rate were generated after time-averaging (20 second) and despiking the data between 2 standard deviations of the 20 second mean values (Amos et al., in prep.). Erodibility was interpreted from the rate of change in SSC detected in the annulus with time throughout each deployment (Amos et al., 1992b) The total suspended 16 mass was determined as the product of mass concentration per unit volume of the annulus (0.216 m3). The eroded depth (mm) was determined by dividing the total suspended mass times the annulus volume by the sediment bulk density dry weight (determined from samples collected when the bank was exposed) times the annulus area. It was assumed that the depth of erosion was equal over the area of the flume. Erosion rates (kg/m2/s) were determined from the change in suspended mass per unit time divided by the area of the annulus (0.873m2). The bed shear stress was determined from a transform of the azimuthal flow using the following equation x0 = Tc^lO" 0 0 0 0 1 7 6^ 0) 2 (Amos et al., in prep) which takes into account the bed shear stress reduction due to suspended sediment concentration (Amos et al., 1992a) where T c o = the clear water bed shear stress = pw*2, p is the density of the overlying water (—1015 kg/m3), SSC is the suspended sediment concentrations, and u* is the induced friction velocity. The cohesive strengths of the sediments at stations 1, 2, 3, 13, and 14 were determined through examination of bivariate plots of effective stress (transform from eroded depth explained below) and applied bed shear stress. The surface intercepts of these plots yield the surface cohesion or the surface critical shear stress for erosion (Tc). This is defined as the maximum shear stress that a sediment can withstand before failure occurs (Brown et al., 1989). The linear failure envelope of the sediment profile is proportional to the internal friction angle ((b) of the sediment, calculated by transforming depth into effective stress o' = yz-P = l.Oz (where y is the unit bulk weight of the sediment, z is the depth in mm and P is the excess pore pressure, assumed to be zero). Then (b = tan-l(A"c/Aa'), where the higher the value of (b, the more resistant the bed is to erosion. The type of erosion (Type I or Type H) was determined from the trends in erosion rate through each 10 minute velocity increment. Type I shows an asymptotic 17 decrease in erosion rate while Type II erosion shows continuous erosion rate through time. The surface critical shear stress for erosion for stations 4, 5, 6, 11, and 12 could not be determined using this method because grain size composition at these stations consisted of fine to medium sands. Sandy sediments do not possess cohesive strength and therefore behave differently than cohesive sediments under applied stress. Cohesive sediments are lifted as clumps or floes and non-cohesive sediments are lifted as individual grains. For this reason the bivariate scatter plot of applied bed stress to SSC was examined to determine the shear stress at which sediments were suspended for the sandy sediments. The migration of sand through ripples resulted in scattered sediment concentrations recorded from the lower OBS. The upper OBS results were used to determine the onset of sediment erosion because results were significantly less variable as only the suspended sediment load and not the bed load was measured. Because sands move through traction, saltation and suspension, the time series of erosion rates and the bivariate scatter plot of eroded depth versus applied shear stress were not plotted. The reason for this is that no mean sediment depth could be determined because of the movement of sand as ripples rather than bed erosion and transport. Determining the rate of bedload transport is a difficult task and has not been undertaken in this study. For the fine sands on Sturgeon Bank we will assume that bed load transport is minor relative to suspended load transport; however, for medium sands this assumption cannot be made so easily. This is because fine sands behave somewhat like silts in that they do not go through a bedload stage (Brown et al., 1989). Velocity measurements at the seabed are extremely difficult to obtain because instruments deployed close to the bed become obstacles and consequently interfere with the flow and sediment dynamics. Therefore instruments are deployed at some measured distance above the 18 seabed. The critical shear stress at the bed can be converted to a critical shear velocity at the bed and subsequently converted into an equivalent velocity at any height above the bed. This is true because the velocity profile in the turbulent layer decreases logarithmically towards the bed due to friction (Brown et al., 1989). The conversion of the surface critical bed shear stress for erosion to current velocities at a height of 50 cm above the bed was determined using the equation for the Law of the Wall or von Karman-Prandtl equation: wy=(w*/K)ln(y/y0), where uy is the current velocity at a height y above the bed, K is the von Karman constant with a value of 0.4, y is the height above the bed in metres, y0 is Nikuradse's roughness length which for transitional and rough turbulent flow conditions is equal to d/30 where d is the diameter of the floes or height of the bed ripples, and u* is the friction velocity which, at the bed, is equal to (t^p)05 (Dyer, 1986) where T c is the critical shear stress for erosion and p is the density of the overlying water column. The flow roughness is determined through the flow Reynolds number and in all cases on the bank the erosion process began under turbulent transitional flows. Suspended sediment transport rates (kg/m2/s) were determined by multiplying the current velocity and the suspended sediment concentration. The transport rate was then plotted against applied shear stress and an equation relating the transport rate to both the applied shear stress and the equivalent current velocity at 50 cm from the bed were determined. 2.3. RESULTS AND DISCUSSION The calibration of the two internal OBS sensors yielded linear and consistent results between stations following the functions: SSC(upper) = 4.1 l(OBS-upper) - 115 (^ =0.89) and SSC(lower) = 3.18(OBS-lower) - 32 (^ =0.88) (Amos et al., in prep). 19 2.3.1. COHESIVE SEDIMENTS 2.3.1.1. Erosion rates A time series plot of the vertical and azimuthal current velocities, the three measures of suspended sediment concentration and the erosion rate for stations SI, S2, S3, S13, and S14 are plotted in Appendix in. It is evident that Type I erosion dominates the initial stages of bed erosion with erosion rates peaking sharply within 30 seconds of flow increase and then decreasing exponentially to zero within 5 minutes (Amos et al., in prep). Two erosion types are evident when referring to Type I erosion behavior. Type LA erosion is observed on the video camera and described as the removal of loose floccules, pellets and organic aggregates found on the sediment surface, probably ephemeral deposits from slack water tidal deposition. Erosion of Type IA was observed only at stations S2, S3 and S14 (Appendix HI) with values of 0.0003, 0.001 land 0.0026 kg/m2/s, respectively. Type IB erosion is described as the erosion of a consolidated seabed possessing a yield strength so the critical shear stress for erosion is measurable. Type IB erosion dominated the non-cohesive sediments on Sturgeon Bank (Appendix HI). Erosion rates for Type IB erosion at stations SI, S2, and S14 are similar with values of 0.0018,0.00125 and 0.00133 (± 0.0005) kg/nr7s, respectively. Stations S3 and S13 show Type IB erosion rates significantly lower with values of 0.00032 and 0.00024 (±0.00005) kg/m2/s, respectively. Type H erosion dominates the latter stages of bed erosion with no significant peak in erosion rate being detected but a continuous erosion rate through time. Type H erosion was only observed at stations SI, S2, and S3 (Appendix US) with peak erosion rates of 0.00067,0.000155 and 0.0004 (±0.00005) kg/m2/s, respectively. The transition from Type IB to Type n erosion occurred in all cases at current speeds of 0.7 - 0.9 m/s. 20 2.3.1.2. Erosion thresholds The surface critical shear stresses for erosion at stations SI, S2, S3, S13, and S14 are 1.6, 2.2,2.0,1.0, and 1.5 Pa, respectively. These values correspond to friction velocities at the bed of 4.0 4.7,4.4, 3.1, and 3.8 cm/s. In order to obtain these critical shear velocities at the bed and initiate bed erosion, velocities at a height 50 cm above the bed would need to be 73, 86, 80, 57, and 69 cm/s, for stations SI, S2, S3, S13, and S14, respectively. That is, currents of this speed are required at a height of 50 cm from the seabed before erosion at the bed may occur. Erosion thresholds measured at depth in the sediments vary considerably but generally follow an increase in sediment strength with depth. Station S1 has a weak layer at depth between 0.3 and 0.5 mm in the sediments which is evident by the negative friction angle indicating a decrease in bed strength with depth (Figure 5). At depths greater than 0.5 mm the sediment strength increases twice with corresponding positive friction angles of 73° and 85°. Station S2 behaves similarly to station SI with a weak sediment layer between 0.05 and 0.25 mm in the sediments as shown by the negative friction angle (Figure 6). At depths below this the sediment strength increases with depth with a friction angle of 65°. Despite the high surface cohesion values at stations SI and S2, the concentration of sediment suspended during the experiment is significantly higher than all of the other stations. This may, in large part, be due to the weak sediment layer present with depth at both stations. Station S3 has a surface critical shear stress for erosion similar to station S2, however, no weak layer is observed in the sediments at this station. The increase in sediment strength with depth following a high friction angle of 87° results in a depth of erosion of 0.3mm over the entire sampling time (Figure 7), significantly lower than the depth of 1.2 mm recorded at stations SI 21 22 23 and S2 over the same time interval. Station S13 behaves similarly to station S3 with an eroded depth of only 0.11 mm over the sampling time interval. The sediment strength increases with depth twice with corresponding friction angles of 89° and 87° with no reversals indicative of weak layers (Figure 8). The sediment behavior with depth at station S14 is unlike any other station in that the eroded depth seems to decrease with increasing applied shear stress. This behaviour can not be explained, however the increase in sediment strength with depth follows an approximate friction angle of 69° (Figure 9). 2.3.2. NON-COHESIVE SEDIMENTS A time series plot of the vertical and azimuthal current velocities and the three measures of suspended sediment concentration for stations S4, S5, S6, SI 1, and S12 are plotted in Appendix HI. Sandy sediments do not exhibit Type I and Type II erosion as bed failure in non-cohesive sediments is not the same as cohesive sediments. Non-cohesive sediments lack the physio-chemical interactions that exist between clay particles and therefore are free to move independently. The surface critical shear stress for erosion at stations S4, S5, S6, Sll, and S12 were determined using the suspended sediment concentration versus the applied bed shear stress plot and are -0.9, 1.25 1.2, 0.0?, and 0.4 Pa, respectively (Figures 10, 11, 12, 13, and 14). These values correspond to friction velocities at the bed of -3.0,3.5,3.4,0.0, and 2.0 cm/s for stations S4, S5, S6, Sll, and S12, respectively and current velocities at 50 cm above the bed of -49, 58, 56,0, and 33 cm/s, respectively in order to initiate sediment suspension. 25 26 o o to CO +-» Z2 CO CO DC ^ co o —5 -r^ O c5 03 CO O co CD (7) a) O CO in o " 8 „ , g a> > il co > | ^ 2 II CO K 00 c' ~ 8 - 11 g m " t o * 5 a. " 3 o >• <0 CO o o oo o CD o o to = t= O CO ;= H 0> o c ° o o * <>? o o o o o$ o c o 'to o UJ < UJ Q. > I-o o <f> o° o oO°o o c\i o d o 2 CO Q_ CO CO CD i_ w 1— CO CD o J= cd GO o o ui o (LULU) u i d e a a o to cx, 60 a c/l a u | CU CO ON a 60 27 ^ 28 30 31 32 2.3.3. SEDIMENT TRANSPORT RATES Only the suspended sediment transport rates (SSTR in kg/m2/s) have been examined in this thesis as bedload transport rates are difficult to obtain and assumed to be minor compared to the suspended load. The best fit regression line was used to describe the sediment transport rate versus applied shear stress and applied current velocity 50 cm from the bed. In many cases the equation followed the power law while in other cases a linear regression best described the data. The slope of the corresponding sediment transport equation gives an indication of the quantity of sediment transported. Station SI transport rates follow the equation SSTR = 1.70(T) - 1.95 where T is the applied bed shear stress (Figure 15a). Converting this equation to represent a function of the SSTR using the velocity at 50 cm from the bed results in the following relationship SSTR = 8.99(u50) - 5.84 (Figure 15b). This equation is valid for bed shear stresses with values up to 2.9 Pa (u50 = 98 cm/s) and then the following relationship describes transport behavior more closely SSTR = 0.74(T) + 1.04 and SSTR = 5.15(u50) + 1.83 using the velocity 50 cm from the bed. The equation showing the relationship of applied current velocity at 50 cm from the bed will hereby be given in square brackets preceding the applied shear stress relationship. Station S2 shows a constant increase in SSTR with increasing applied shear stress following the equation SSTR = 1.26(T) - 1.73 (Figure 16a) [SSTR = 7.02(u50) - 4.85 (Figure 16b)]. The suspended sediment transport equation for station S3 is a power function following the equation SSTR = 0.008(T)2-02 (Figure 17a) [SSTR = 0.078(u50)403 (Figure 17b)]. Station S13 behaves similar to station S3 in that it follows it follows the power law with an increase in SSTR with increasing applied shear stresses following the relationship SSTR = 0.002(i;)2-33 (Figure 18a) [SSTR = 0.027(u50)467 33 0 ^ 6 Q. CM C ^ -*—' C ^ ( D C . E 22 <1> E „ (0 03 3 "O W T3 C o S I Q. S 2 1 Sea Carousel Results Station 1 • Data used for regression O Data removed for regression S S T R = 0.7377(T) +1.1045 R 2 = 0.8967 • • 2 3 4 Shear stress (Pa) 5 4-Q. CM C ^ « CD ( D C . E -w rt 3 T3 (0 0) 3 T3 C P (D t Q. (0 0) 1 00 rt Sea Carousel Results Station 1 • Data used for regression O Data removed for regression • • 0.2 - + -0.4 S S T R = 5.1519(1150)-1.8299 R 2 = 0.8786 S S T R = 8.9936(U50) - 5.8412 R 2 = 0.797 1.2 — I — 1.4 0.6 0.8 1 1.6 Current velocity at 50 cm from seabed (m/s) 1.8 Figure 15: Suspended sediment transport rate for sediments at station 1. 34 4.5 S £ 4 Q_ CM « E 3.5 2 g CD c . £ 0 2.5 I Sea Carousel Results Station 2 • Data used for regression O Data removed for regression 4.5 S £ 4 CL CM co 5^) ~ 3 C C CD C E 9? 2 5 CD E o co co TJ cn S I 1 CO CD W 2 0.5 0 o o o 0 Sea Carousel Results Station 2 • Data used for regression O Data removed for regression SSTR = 7.0195(1150) - 4.8495 R2 = 0.8399 0.2 0.4 0.6 0.8 1 1.2 Current velocity at 50 cm from seabed (m/s) 1.4 Figure 16: Suspended sediment transport rates for sediments at station 2. 35 1.4 CD ^ § " £ 0.2 GO 2 Sea Carousel Results Station 3 4 6 8 Shear stress (Pa) 12 1.4 Sea Carousel Results Station 3 o 42 1.2 Q. CM s ^  CO O) 1 CD C E .2 ' 1 0.8 4-CD _ CO CO 0.6 T J CO CD 3 C | 0.4 CD t CO CD CO CO 0.2 SSTR = 0.0776(U50) R2 = 0.9114 I I f I I I I 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 Current velocity at 50 cm from seabed (m/s) Figure 17: Suspended sediment transport rate for sediments at station 3. 36 Sea Carousel Results Station 13 ^ 1 1 1 1 1 h 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 Shear stress (Pa) 0.35 O -J2 0.3 Q. CM ' 2 S5 0.25 •4—' c ^ 0) c E .9> ' 1 0.2 CD _ to co 0.15 TJ to CD 3 TJ C S I CL CO CD 5 0.1 co 2 0.05 Sea Carousel Results Station 13 «* • • SSTR = 0.027(U50)' R2 = 0.8831 — * I ' • 0.5 1 1.5 Current velocity at 50 cm from seabed (m/s) Figure 18: Suspended sediment transport rate for sediments at station 13. 37 (Figure 18b)]. Station S14 shows two distinct trends in sediment transport behavior and, like station S1, transport rates increase faster at lower applied shear stresses following the relationship SSTR = 0.55(T) -1.01 (Figure 19a) [SSTR = 3.47(u50) - 2.79 (Figure 19b)] up to an applied shear stress of 4.3 Pa (u50 = 120 cm/s) and then follow the relationship SSTR = 0.25(T) + 0.37 [SSTR = 2.32(u50) + 1.38] for applied stress greater than 4.3 Pa. The data for suspended sediment transport rates for sandy sediments are somewhat more scattered than for the cohesive sediments probably because of the influence from saltating particles. Suspended sediment transport at station S4 is best described by the following power law equation SSTR = 0.044(T)288 (Figure 20a) [SSTR = 1.98(u50)576 (Figure 20b)], while suspended sediment transport at station S5 follows the power law equation SSTR = 0.025(T)246 (Figure 21a) [SSTR = 0.66(u50)491 (Figure 21b)]. Suspended sediment transport rates are difficult to decipher at station S6 because of the large scatter in the data, however the approximate power function SSTR = 0.062(x)216 (Figure 22a) [SSTR = 1.08(u50)431 (Figure 22b)] best describes the transport behavior here. The suspended sediment transport behavior at station Sll follows the power law relationship SSTR = 0.66(x)'28 (Figure 23a) [SSTR = 0.36(u50)255 (Figure 23b)]. The almost zero intercept for the SSTR equation implies that sediments start eroding almost at the onset of any applied stress. Although this is not likely, it is obvious that the sediments at station S11 are being suspended at very low applied shear stresses, probably less than 0.25 Pa (u50 = 26 cm/s). Station S12 shows a power function increase in SSTR with increasing applied shear stress following the relationship SSTR = 0.074(x)'54 (Figure 24a) [SSTR = 0.57(u50)308 (Figure 24b)]. 38 3.5 Q. CM CO D) iz CD C E .2 ( D C , . CO CO 1-5 Sea Carousel Results Station 14 • Data used for regression O Data removed for regression 4* SSTR = 0.2501 (T) + 0.3663 R = 0.9285 SSTR = 0.5486(T) -1.0102 • • R2 = 0.6319 4 6 8 Shear stress (Pa) 10 12 Sea Carousel Results Station 14 3.5 -1 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 Current velocity at 50 cm from seabed (m/s) Figure 19: Suspended sediment transport rate for sediments at station 14. 39 Sea Carousel Results Station 4 Shear stress (Pa) Sea Carousel Results Station 4 Current velocity at 50 cm from seabed (m/s) Figure 20: Suspended sediment transport rate for sediments at station 4. 40 1.4 Sea Carousel Results Station 5 1.5 2 2.5 3 3.5 Shear stress (Pa) 1.4 0 5f Q . CM 1 2 CD O) . ±z ^ 1 » 1 i 0.8 =6 £ CD C CO CO 0.6 T J CO CD 3 . £ 0.4 S E 0.2 G O CO Sea Carousel Results Station 5 SSTR = 0.6581 (U50)4 9 1 4 2 R 2 = 0.8281 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 Current velocity at 50 cm from seabed (m/s) Figure 21: Suspended sediment transport rate for sediments at station 5. 41 Sea Carousel Results Station 6 Shear stress (Pa) Sea Carousel Results Station 6 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Current velocity at 50 cm from seabed (m/s) Figure 22: Suspended sediment transport rate for sediments at station 6. 42 Sea Carousel Results Station 11 £ £0.9 Q. CVJ n t t CO C 0.8 C -5 CO D) „ _ ^ 0.7 CD c E .2> CD E (0 CO • • SSTR = 0.0659(T) R2 = 0.859 2 3 4 5 Shear stress (Pa) Sea Carousel Results Station 11 0.9 + S 3 Q. CM „ „ to C 0.8 C -EE CO D) „ _ £z 0.7 CD C E .2 CD E to CO 0.6 0.5 0.4 + .= 0.3 TJ tO CD 3 TJ C S I w 2 o.i 04-SSTR = 0.3586(U50)1 R2 = 0.859 • • • • 0.2 0.4 0.6 0.8 1 1.2 Current velocity at 50 cm from seabed (m/s) 1.4 Figure 23: Suspended sediment transport rate for sediments at station 11. 43 a. cvj 21 CO D ) >— v ; C C CD C E .9> CD E CO CO X J co CD 3 T J C S I CO CD CO 2 0.8 0.7 + 0.6 0.5 0.4 0.3 4-0.2 Hi 0.1 Sea Carousel Results Station 12 SSTR = 0.0737(T) R2 = 0.7749 Shear stress (Pa) 4.5 0.8 C L CNJ CO D ) 0 6 f £S» C CD C E .2 TJ -g CD E CO CO TJ CO CD 3 TJ C S I Q. CO CD C  0.7 0.5 0.4 4-0.3 4-F 0.2 •s 0 1 + co 0.1 Sea Carousel Results Station 12 SSTR = 0.5667(U50) R2 = 0.7749 —h-0.2 —I— 0.3 0.6 0.7 0.8 0.9 Current velocity at 50 cm from seabed (m/s) 1.1 Figure 24: Suspended sediment transport rate for sediments at station 12. 44 Chapter 3. PHYSICAL OCEANOGRAPHY 3.1. THE S4 CURRENT METERS AND FIELD SAMPLING Physical oceanographic data were collected from 10 sites on Sturgeon Bank during May and June, 1993. The sampling stations corresponded with the Sea Carousel sites and the sampling time overlapped with both the Fraser River freshet which peaked on May 20 at 8890 m3/s and suspended sediment sampling. An InterOcean S4 current meter was deployed at stations S2, S4, S6, SI2, and S14 from May 7 to June 3 and a current meter was deployed at stations SI, S3, S4, S5, Sll, and S13 from June 3 to June 30 (See Figure 4). A description of the study is also found in Feeney (1994). The current meters were calibrated in the laboratory for salinity, temperature, direction, and velocity. They were also cold-temperature-tested to insure they would continue data collection if temperatures on the bank decreased drastically. Aluminum poles, 1-1.5 m in length, were screwed into the base of the current meter and then shoved, by hand, into the sediments. A plexiglass plate was placed on the rod 30 cm below the base of the current meter to ensure that it did not sink further into the sediments over the month of deployment. The electrodes which measured current velocity and direction were situated 50 cm from the seabed, while the instruments collecting temperature, salinity and depth measurements were situated on the top of the current meter approximately 75 cm from the seabed. Each current meter was programmed to sample every 1.5 seconds for speed and direction of currents. After 10 data entries (15 seconds) an additional line of information which included conductivity, temperature, density and salinity were recorded. This procedure was repeated 3 45 times (a total of 1 minute) after which the instrument shut itself off for the following 59 minutes. On the next hour, the S4 would "wake up" and begin sampling again every 1.5 seconds for one more minute, recording additional data at the end of every 15 seconds. 3.2. DATA REDUCTION See Appendix IV for a detailed description of the physical oceanographic data. The data were carefully analyzed to determine when the tide was at a sufficient height to cover the electrodes on the current meter. This was possible because the current meter deployed at station S4 was equipped with a pressure sensor to measure depth of inundation. The depths at station S4 acted as a guide to determine the times when current meters at the other stations were inundated. Data from station S4 were not used unless a depth of 0.5 m was recorded which ensured that the electrodes collecting the measurements were sufficiently submersed. Data collected at station S5 were not used unless a depth of 0.5 m was being recorded at station S4, while data collected at stations S6, S1 land S12, were not used unless a depth of 0.1 m was being recorded at station 4. For stations S2, S3, S13 and S14, data were not used unless a depth of 1 m was being recorded at station S4 and station S1 data were not used unless a depth of 1.5 m was being recorded at station S4. Conductivity measurements assisted in the determination of current meter exposure or inundation. Ignoring the first and last hour of data collected with good conductivity measurements ensured that no questionable data were included. Current directional data for each station were divided into 10° increments and plotted as frequency of occurrence. Both a rose diagram and frequency histogram were produced for ease in data visualization. The velocities associated with each 10° class interval were averaged and 46 plotted on frequency diagram to show the current velocities associated with their directions (See Appendix IV - Figures 91, 96, 101, 108, 109, 119, 124, 129, 136, 141, 146). Velocities were also determined by averaging all the data points produced in one minute (See Appendix IV - Figures 89, 84,99,104,105,116,122,127,132,139,144). It was assumed that wave periods did not exceed a few seconds in duration and therefore averaging the data over one minute effectively filtered out the effects of waves. High-frequency velocity fluctuations which are assumed to result from waves were determined directly from the S4 data by considering each individual data point in each one minute sampling interval (See Appendix IV -Figures 90, 95, 100, 106, 107, 117, 118, 123, 128, 133, 134, 135, 140, 145). Sampling periods were selected randomly, choosing intervals where wave current velocities were higher than average, then these values were plotted against direction. This allowed visualization of the dominant current directions and their associated velocities in a way similar to the method described for the 10° increment data. Temperature and salinity measurements were plotted for the entire sampling period for each station (See Appendix IV - Figures 92,93,97,98, 102,103, 110, 111, 112,113, 120, 121, 125, 126, 130, 131, 137, 138, 142,143, 147, 148). The current meter at station 4 was equipped with a pressure sensor which measured depth and therefore depth was plotted for the sampling period (See Appendix IV - Figures 114,115). 3.3. R E S U L T S A N D DISCUSSION 3.3.1. 10° INCREMENT-AVERAGED VELOCITY AND DIRECTIONAL DATA Current directional data on Sturgeon Bank are variable (Figure 25). Stations S3, S4, S5, 47 North Arm Jetty North Arm Figure 25: Current direction plots for 10° averaged increments 48 S6, S11, S12, and S13 show strong bidirectional flows due to flooding and ebbing tides, while stations SI, S2, and S14 show a more random distribution of flow frequencies in all directions. Flows at stations S4 and S11 are dominantly toward 50° in a flooding direction and 225° in an ebbing direction, while flows at stations S3 and S5 are dominantly toward 85° and 235°. Flooding and ebbing flow directions at station S6 are dominantly toward 95° and 250°, respectively, with flooding and ebbing flow directions at station S13 being less focussed and dominantly toward 80° and 270°, respectively. Although station S12 has a strong bidirectional flow toward 95° and 240° for flooding and ebbing tides respectively, an additional component of flow southwards toward the Steveston jetty may be indicative of flow towards an opening in the Steveston jetty on a flooding tide. Particular stations on Sturgeon Bank seem to be more affected by currents in a flooding direction while others are more affected by currents in an ebbing direction. This is likely the result of the seabed morphology which focusses tidal flows to certain areas of the bank. Flooding directions, averaged over 10° increments, occur more often at stations S3, S5, S6, S12, and S14 (Appendix IV - Figures 101, 119, 124, 136, 146). Ebbing directions, averaged over 10° increments, occur more often at station S4 in May and station SI3, while ebbing and flooding directions occur equally at station S4 in June and station S11 (Appendix IV - Figures 108, 141, 109, 129). Average velocities associated with each 10° increment are higher in the flood direction at stations SI, S2, S3, S4, S5, Sll, and S12, with values of 7.8, 8.3,17.5,23.0,23.0, 21.0, and 18.0 cm/s, respectively, while velocities in the ebb direction are higher at stations S6, S13 and S14 with values of 24.0,11.0, and 15.0 cm/s, respectively (Figure 26a4c). Direct station comparisons must be made cautiously because in some cases the data has been collected in 49 3 + Station 1, June 3 - June 30, 1993 m i r ) i f ) i i ) i n i r ) i o i r ) i o l o m >o m t o t o o m l O i o t o i o i q i o t o i O L O i o i O L O w i o m ^ N r o ^ m o s c o o - O •— C N co ^ io -or--- c o o > 0 ' - C N C ) t r i f l ' O N c o O ' o •— C M — _ _ _ _ _ — C N C N C N C N C N C N C N C N C N C N C O C O C O Station 2, May 7 - June 3, 1993 18-r i o t o i f i i n i n m m m i o m i o m L O L O L O L O i n i o i n ^ i o i f i m i o i f l i o i o i r ) m L O t o r ^ r^" ^ 'd 1 )>0NC0f>Oi-CN(0'3li)<0NCrjt> O — CM - — — — .— C M C M C M C M C M C M C M C M C M C M CO CO CO T *J ( O T if) C O C O C O Station 3, June 3 - June 30, 1993 25 i o t o L O m uo t o L O L O to to L O to to io l O i o i o m i o i n i n i o i n i o i o i o i n m i o i o L O L O t o ^ r- CN CO -^J LO O N CO 0 > O *— CM CO If) - O N O O O O — C M c O ^ T L O O r ^ O O O O •— CN — — — — — — — — — — C N C N C M C M C M C N C M C N C M C N CO CO CO "ST 20 + _ 15 10 L O L O I O CO CO cO Station 4, May 7 - June 3,1993 L O L O L O L O L O L O L O L O ^ O L O L O L O L O L O L O L O L O L O L O L O L O L O L O L O L O L O L O L O L O up L O L O L O L O O — C N c O T f i O O N C O O - O •— CN O 1 IX) C M C M C M C > I C M C M C M C M C M C M C O C O C O C O C O C O Station 4, June 3 - June 30, 1993 L O L O L O L O L O L O L O L O L O L O * 0 L O L O L O L O L O L O L O L O L O L O L O L O L O L O L O L O L O L O L O IT) l O IT) L O L O L O Direction (°) Figure 26 a-e: Current speed plots for 10°averaged increments for stations 1, 2, 3, 4 (May), and 4 (June), respectively 50 25 20 15 10 + 5 0 25 20 15 10 5 0 Station 5, J une 3 - June 30 , 1993 I D m m m m m m m io m ^ uo m t o r n L O L O m m m m m m L O L O L O L O to i o L O L O to m m m l O - O r - O O O O i - t N f O T t l f ) > O r s c O t > O i - C M r O ^ J - i O > O r - * C O O - C D •— O J CO U ) .— •— .— •— •— •— •— •— .— .— t N C N C N C N t N i N C M C N C N C N C O C O C O C O C O C O i — C N tO T J -g Station 6, M a y 7 - J une 3, 1993 L O L O L O U ) U ) l O L O L O L O "-O L O i O L O L O L O L O L O I O L O L O L O L O I O L O L O L O L O L O L O L O C O L O L O L O L O ^ C N I < ^ 5 S 3 N S i> o ^ « w 5 S 3 r s S 3 S ' w t o 5 S 3 s S i > 3 ^ C M <o 5 3 '— f— .— r— ,— i— • — f — f — C M C M C M C M C M C M C M C M O I C M CO CO CO CO O CO 25 20 15 10, 5 0 1 8 T 16 14 12 10 + 8 6 4 T 2 0 Station 11, J une 3 - J une 30 , 1993 L O L O IT) I D L O L O L O L O L O L O L O if> L O CO L O L O L O L O i f > L O L O L O L O L O L O F L O - O r--» O O 0 - CTD • — CN* C O Station 12, M a y 7 - June 3, 1993 L O I O L O L O L O L O L O L O 1 ^ ? L O L O L O L O L O L O L O L O L O L O L O L O L O L O L O L O L O CM ro i n - O r—. co O - CD •— OJ to T J io -o i s ( 12 10 8 6 4 2 0 L O L O m m m TT ' s j ' i — - O •— Csl t o c o c o L O L O L O •*r c o c o co* Station 13, J une 3 - June 3 0 , 1 9 9 3 L O L O L O L O L O L O L O 1 ^ u } i n u ) u i i n i o i r ) i o u ) i n > o u ) i r ) U ) U ) i o i o i o i A TT TT -^ j ID m m m i f ) i f ) 16-, 14-12-10-8 ; 6-4-2- k C D •— C N t o T T T TT TT C O Q - Q • — C M C O C M CSI C O C O C O C O C O Station 14, M a y 7 - June 3, 1993 IX) L O L O T T T T r— C M L O L O L O L O L O L O L O i f ) L O L O L O L O L O L O «f> «f> L O L O L O U"> L O L O L O L O L O L O L O L O L O i f ) t f ) i f ) T T T T ' T T T T T T ' T T T T ' ^ S " TT TT TT TT TT TT TT TT TT TT TT TT TT T ' T ' TT TI" TT TT TT *r e o - ^ r i o - o r - v o o o o >— c N t o t r m o r s t o o p i — c N t o T i o - O N c o O ' o • — C M c o L O i — i — . — . — . — i — i — . — . — i — C M C M C M C M C M C M C > I C M C N I C ^ c O e O e O « O f O C O Direction (°) Figure 26 f-k: Current speed plots for 10° averaged increments for stations 5,6,11,12, 13, and 14, respectively 51 different months. Higher ebbing velocities at lower frequencies at stations S6 and S14 may be the result of a strong influence from the Middle Arm of the Fraser River on ebbing tides. Because the frequency of flow in the ebbing direction is low, these speeds must only be reached for short times during the tidal cycle. Station S14 is situated adjacent to the south side of the mouth of the Middle Arm and station S6 is on the outer bank where flow from the Middle Arm (or a channel from the Middle Arm) reaches the edge of the bank. The influence of the Middle Arm flow at these two stations would be supported by strong variations in salinity and temperature within sampling intervals as the salt water from the Strait of Georgia is replaced by fresh water from the river on an ebbing tide. This pattern is observed at both stations S6 and S14, where observed variations in salinity and temperature are higher relative to all the other stations on the bank (Appendix IV - Figures 125,126, 147, 148). Salinity at station S14 remains lower compared to station S6 because of its proximity to the shore, which results in tidal inundation for shorter periods of time. Lower salinities occur at all of the inner bank stations for the same reason. Based on the results from station S4, ebbing tidal directions occur more frequently in May than in June (Appendix IV - Figures 108,109), likely due to the effect of a larger source of water from offshore because of the increasing Fraser River flow and the slight increase in spring tidal height in June. The higher frequency of occurrence of ebbing tidal directions in June at station S13 is therefore likely preceded by an even higher frequency in May. Station S13 is the only station where the ebbing velocities are both higher than flooding velocities and occur more often (Appendix IV - Figure 141). Station S13 is situated close to a channel connected to the Main Arm of the Fraser River through an opening in the Steveston jetty and therefore probably 52 maintains a large degree of flow seaward even at higher tides. 3.3.2. ONE-MINUTE-AVERAGED VELOCITY DATA The highest velocities averaged over 1 minute recorded in May occurred primarily in the sampling interval May 11 (1900 h) to May 12 (0100 h) with the May 12 (0600-1300 h) and the May 28 (1800 h) to May 29 (0600 h) intervals also recording high velocities at stations S12 and S4, respectively (See Appendix IV - Figures 94,104,122,132,144). The highest tidal velocities recorded in June occurred in several sampling intervals including June 3 (1400 h) to June 4 (0900 h), June 4 (1400 h) to June 5 (0900 h), June 6 (1500 h) to June 7 (1100 h), June 9 (2100 -2400 h), June 21 (1900-2200), June 23 (1800 h) to June 24 (0100 h), June 24 (1600 h) to June 25 (0400 h), June 25 (1700 h) to June 26 (0300 h), and June 26 (1900 h) to June 27 (0300 h) (See Appendix IV - Figures 89, 99, 105, 116, 127, 139). The highest velocities averaged over one minute were recorded at stations S6, S12 and S14 in the May 11-12 sampling interval with values of 27.8, 24.92, and 20.4 cm/s, respectively (Appendix IV - Figures 122, 132, 144). It must be observed that these values represent the average velocities over a one minute sampling period and therefore incorporate currents due to waves if they are high in that minute of sampling. Averaging these one minute intervals over the whole inundation period tends to filter out some of these high hourly fluctuations. However, if waves remain high throughout the entire sampling inundation, the higher average velocity recorded in that interval may be largely the result of persistent waves rather than tides. Examination of the high-frequency velocity fluctuations revealed that high averaged velocities recorded on May 11 and 12 and June 4, 6, and June 21 were likely due to the waves which 53 persisted throughout each of these sampling intervals and not due solely to tidal currents. The high one minute averaged velocities recorded in the other intervals mentioned above also show some degree of influence from the wave climate that existed on the bank at the time of sampling. The one minute averaged velocity values obtained from stations S12 are considerably higher than the values obtained from more seaward station Sll (Appendix IV - Figures 132, 127), perhaps because of its proximity to a tidal channel (See Figure 4). The values obtained from station S14 are considerably higher than stations SI, S2, S3, and S13, also adjacent to the shore, and stations S4 and S5 in the middle bank area probably due to the influence of the Middle Arm flow (Appendix IV - Figures 148,89,94,99,139,104,105,116). At station S4, where data was collected in both May and June, the average velocity over each month was the same, however, the highest one-minute-averaged velocities recorded within a sampling interval at station S4 occurred in June (Appendix IV - Figures 104, 105). Average velocities, in general, are higher at the stations sampled in June. The analysis of surface currents at the seaward edge of Sturgeon Bank conclude that currents flow north at 26 to 51cm/s (Giovando and Tabata, 1970; Tabata et al., 1971). These results are not consistent with the results obtained from this survey where average velocities at the edge of the bank are commonly twice as high as those observed in the previous study. Current meters used in this study measured currents 50 cm from the seabed rather than the sea surface, so the results of the studies cannot be directly compared. 3.3.3. HIGH-FREQUENCY VELOCITY FLUCTUATIONS (WAVES) High frequency sampling results (waves) are similar to low frequency (averages) patterns on Sturgeon Bank in that they vary widely. Maximum wave velocities reach 90 cm/s at station 54 SI 1,90 cm/s at station S6 and 83 cm/s at station S12 (Figure 27i, j, k). Stations SI, S2 and S13 show the lowest with maximum values of 38, 43, and 42 cm/s, respectively (Figure 27a, b, d), and stations S3, S4, S5, and S14 show maximum velocities of 47, 53, 62, and 60 cm/s, respectively (Figure 27c, f, g, h, e). Maximum wave velocities at station S4 are slightly higher in June than in May and high velocities are reached almost 3 times more often in June (Appendix IV - Figures 106, 107). Wave velocities in a flooding direction generally exceed those in an ebbing direction except station S14. Ebbing velocities also have a large influence at stations S6, Sll, S12 and S13 and the maximum wave velocities at all stations often occur in ebbing directions (Appendix IV - Figures 145, 123, 128, 133, 134, 135, 140). 3.3.3.1. Erosional capabilities of currents on Sturgeon Bank Velocities capable of eroding sediments on Sturgeon Bank are never reached on the inner bank at stations SI, S2, S3, S13 and S14 (Figure 27 a-e) and are only reached at stations S4, S5, S6, Sll, and S12 (Figures 27 f-k) if high-frequency fluctuations are considered. Wave energy dissipates as it moves shoreward across the bank in a method consistent with that described by Medley (1978). The critical shear velocity for erosion of sediments at station S4 (i.e. 49 cm/s at a height of 50 cm from the seabed) is reached only once in May (Figure 27f) and 12 times in June (Figure 27g). Using the sediment transport equation determined in chapter 2, 0.04 kg/m2/s of sediment is transported in an ebbing direction in May and 0.56 kg/m2/s of sediment is transported in a flooding direction in June at station S4. Currents at station S5 reach the critical shear velocity for erosion (i.e. 58 cm/s at a height of 50 cm from the seabed) only 6 times in one month of data collection (Figure 27h) and resulting sediment transport values are 0.17 kg/m2/s in an 55 ^ 50 JO 45 + E 40 3, 35 "§ 3 0 Q 25 CO 2 0 + Current speeds for station 1 Critical shear velocity for sediment erosion at 50 cm from the seabed = 73 cm/s • 30 * * • A . 50 100 150 200 250 300 350 50 45 CO E O 40 CD CD CL CO 35 30 25 Current speeds for station 3 Critical shear velocity for sediment erosion at 50 cm from the seabed = 80 cm/s • 2fe 50 100 150 200 250 300 350 45 E 4 0 C3. 35 " § 30 CD Q_ 25 CO 20 Current speeds for station 13 Critical shear velocity for sediment erosion at 50 cm from the seabed = 57 cm/s 50 100 150 200 250 300 350 42 70 | 60 xT 5° + 0) 40 20 Current speeds for station 14 Critical shear velocity for sediment erosion at 50 cm from the seabed 50 100 150 200 250 300 350 400 Direction Figure 27: Highest current velocities recorded at each station through one month S4 deployments 56 60 55 "g l o 50 <P E 45 4-Q. CO O 40 --35 -30 0 Current speeds for station 4 - May, 1993 Critical shear velocity for sediment erosion at 50 cm from the seabed = 49 cm/s -+-50 100 150 200 250 300 350 60 _ ^ 5 5 Q 50 <P E 45 O .40 Q . CO 35 30 Current speeds for station 4 - June, 1993 Critical shear velocity for sediment erosion at 50 cm from the seabed = 49 cm/s 50 100 - I -150 200 250 300 350 70 65 CO 45 40 35 Current speeds for station 5 Critical shear velocity for sediment erosion at 50 cm from the seabed = 58 cm/s 50 100 150 200 250 300 350 105 95 i f s t 45 + 35 Current speeds for station 6 Critical shear velocity for sediment erosion at 50 cm from the seabed • =56 cm/s • • 50 100 150 200 250 300 350 75 --T J - £ - 6 5 CD -J2 <D ^ 55 C O - 4 5 35 Current speeds for station 11 Critical shear velocity for sediment erosion at from the seabed 26 cm/s -^ 1,50 * c__* " j j g j l l 150 200 250 300 350 85 —.75 + CD « 65 -I-_ E 5 5 CO 3 4 5 35 +. 25 Current speeds for station 12 Critical shear velocity for sediment erosion at 50 350 Direction Figure 27 cont'd: Highest current velocities recorded at each station through one month S4 deployments 57 ebbing direction and 0.14 kg/m2/s in a flooding direction. The critical shear velocity for erosion of sediments at station S6 (i.e. 56 cm/s at a height of 50 cm from the seabed) is reached 56 times in the month of current meter deployment (Figure 27i). Despite the higher frequency of occurrence of velocities over 56 cm/s in the flooding direction, the higher overall velocities in the ebbing direction result in a higher sediment transport rate. Sediment transport in the flooding direction at station S6 over the month of May was 4.24 kg/m2/s, while sediment transport in the ebbing direction was 4.88 kg/m2/s. Station Sll shows sediment transport rates significantly higher than other stations on Sturgeon Bank because of the low critical shear velocity for erosion (i.e. -26 cm/s at a height of 50 cm from the seabed). The critical shear velocity for erosion is reached 1771 times with the highest frequency of occurrence in the flooding direction (Figure 27j). This high-frequency results in a sediment transport rate in the month of June at station Sll of 21.87 kg/m2/s in the flooding direction and 11.69 kg/m2/s in the ebbing direction. Station S12 current velocity data is similar to station S6 in that the critical shear velocity for erosion is reached more often in a flooding direction but is exceeded by a much greater amount in the ebbing direction (Figure 27k). However, unlike station S6, the sediment transport rate in the flooding direction 9.11 kg/m2/s is greater than the sediment transport rate in the ebbing direction 7.14kg/m2/s. Critical shear velocities for sediment erosion are reached less than 0.3% of the total inundated sampling time at stations S4, S5 and S6 and therefore sediment transport at these stations is very low. Critical shear velocities for sediment erosion at station Sll and S12 are reached 8.4% and 2.5% of the total inundated sampling time, respectively, significantly more often than the other stations and therefore sediment transport rates are considerably higher. 58 Unfortunately, some of the data may not be included in these sediment transport calculations. Currents which act on the seabed as the tide (and waves if they exist) approaches and departs from the station may have a significant effect on the sediment transport, including at stations on the inner bank. However, these current data have not been collected because the electrodes on the current meter are at a height of 50 cm from the seabed requiring at least this water depth before reasonable data is recorded. Data collection, therefore, is missed on the initial incoming tide and on the final outgoing tide. It is very difficult to collect current velocity and directional information at or near the surface of the bed because of instrument interference on current dynamics. It is therefore likely that all sediment transport rates on Sturgeon Bank are higher than what has been calculated here. Current meters deployed in the month of May recorded the highest wave velocities in the interval May 11 (1900 h) to May 12 (0100 h) with station S12 also showing high values in the intervals May 12 (0600-1300 h) and May 23 (0500-0900 h) (Appendix IV- Figures 95, 106,123, 133,134,135). Wind speeds on May 11,12 and 23 were the maximum recorded for the month of May (Environment Canada-Monthly meteorological summary, May/June, 1993) with average speeds during each interval of 26.6 (WNW), 29.1 (WNW), and 26.6 (WNW) km/hr, respectively and maximum daily gusts occurring during the May 11 and May 12 intervals with values of 46 and 48 km/hr. Critical shear velocities capable of eroding sediments at stations sampled in May (i.e. S4, S6 and SI2) are all reached in the May 11 interval. Wind-induced waves are likely responsible for a majority of the sediment erosion and transport on the bank as eroding velocities are rarely reached unless storm conditions persist. The highest wave velocities were recorded in several intervals in June, including June 4 59 (1400 h) to June 5 (1900 h), June 6 (2300 h) to June 7 (1000 h), June 19 (0400-0800 h), June 20 (1600-1700), and June 21 (1900-2200 h) with only stations S4 and SI 1 and stations S5 and S12 showing highest values in the same interval (Appendix VI - Figures 90,100,107,117,118,128, 140). Wind speeds on June 4, 6, 19, 20 and 21 are variable with average speeds during each interval of 13.7 (WNW), 23.8 (WNW), 8.83 (E), 19.0 (WNW) and 17.75 (NW) km/hr, respectively and maximum daily gusts occurring during only the June 21 interval with a value of 35 km/hr. Critical shear velocities capable of eroding sediments at stations sampled in June (i.e. S4, S5 and S11) are reached in a number of sampling intervals, especially at station 11, however a majority of these high velocities are reached in the June 4 - June 5 interval. Since the wind speeds in the June 4 June 5 interval are low, and the interval corresponds to the maximum spring tidal cycle, it is possible that currents associated with this large tide as well as wind generated currents are capable of eroding sediments at these stations in June. The maximum wave velocities in the month of June do not correspond to average daily wind speed measurements, however they do show a much greater association with the spring/neap tidal cycle than the values recorded in May. It is clear that the presence of waves affects the current velocities everywhere on the bank, however, current velocities are also influenced by tidal effects. The tidal influence on current velocities on Sturgeon Bank is more apparent in June. 3.3.4. TEMPERATURE AND SALINITY VARIATIONS Temperature measurements throughout the sampling period show the influence of the spring/neap tidal cycle with warmer water occurring during neap times due to lower tidal heights. High winds have a tendency to bring colder deep Strait of Georgia water to the surface and 60 consequently to Sturgeon Bank which may explain the large temperature drop on June 21 at the stations sampled during this month (Appendix IV - 92,111, 120,130,142). Temperature ranges throughout the sampling period are highest in May with temperatures dropping to lower values during this month (Appendix IV - Figures 97,110,125, 137,147). Typical temperatures ranged from 9 to 26°C with the highest temperatures recorded on the inner bank. The largest temperature ranges throughout the survey occur at stations S1 and S2 with maximum ranges of 11 and 14°C, respectively (Appendix IV - Figures 92, 97). This is likely the result of the predominantly shallow water at these stations which tends to be heated more quickly than the deeper water at other stations. Each station varied in temperature over both the sampling period and each sampling interval. Temperature variations within single sampling intervals are highest at stations S2, S5, and S14, reaching 7° C, and lowest at stations SI and S3 (Appendix IV -Figures 97, 120, 147, 92, 102). Salinity measurements throughout the sampling period show only slight influence from spring/neap tidal effects. This is due to the large within-interval salinity variations which effectively mask the trace of monthly tidal influences. Salinity varies widely at each station with variation throughout the sampling period showing a range from 0%o to 30%o and the variation within a single sampling interval reaching 21%o (Appendix IV - Figures 93, 98, 103, 112, 113, 121,126, 131,138,143,148). The highest degree of variation occurs at station 6 with the outer bank stations generally showing the largest variations. The range in salinity values recorded at the stations is higher in May than in June likely because of the larger influence from the more saline Strait of Georgia water which is able to reach the bank more easily in May than in June when the less saline Fraser River water dominates flow on the bank. 61 Chapter 4. SUSPENDED SEDIMENT 4.1. FIELD SAMPLING Suspended sediment samples were collected from stations SI, S2, S3, S4, S5, S6, Sll, S12, S13, and S14 on Sturgeon Bank (See Figure 4) every third or fourth day from May 14 to June 28, 1993. The sampling stations corresponded with the Sea Carousel and current meter sampling sites and overlapped with the deployment time of the current meters. Suspended sediment sampling also coincided with the peak in Fraser River discharge on May 20. Samples were collected using a DH48 bottle sampler at times as close to high-water slack-tide as possible to remove the effects of the flooding and ebbing tidal currents. It was not always possible to adhere to these sampling times because of the availability of the hovercraft. The water depth was tested prior to the deployment of the sampler and then the instrument was lowered from the hovercraft slowly and at a constant speed until a depth just above the seafloor was reached. The sampler was then brought to the surface at the same speed as the descent. The DH48 sampler is designed to collect a depth-integrated water sample by controlling the speed at which the water enters the sampling bottle. Unfortunately, the rate at which the sampler was lowered and raised was difficult to maintain because of hovercraft movement in the presence of waves or swells. Each station was sampled three times. Where the water depth was less than 1 metre, the sampling bottles were dipped by hand into the water to a depth of approximately 0.5 metres to collect the sample. This procedure had to be adopted because the draft of the hovercraft tended to stir up the bottom sediments too quickly to take the samples with the DH48 at water depths 62 less than 1 metre. Suspended sediment concentrations measured at stations SI and S2 were most susceptible to this problem and therefore their results should be viewed cautiously. 4.2. ANALYTICAL TECHNIQUES Water samples were filtered through 0.045 pm Millipore® filters no more than 48 hours after sampling. This pore size corresponds to the defined boundary between dissolved and suspended sediment and the suspended sediment concentration (SSC) is operationally defined as the amount of sediment retained on the type of filter being used (Loring and Rantala, 1992). Millipore filters have well-defined pore sizes that give them a relatively precise cutoff in the size of particles they retain. They are made of a polycarbonate material which is relatively metal-free and hydrophobic, making them easy to tare and reweigh after sample collection. However, since the build up of particles modifies the effective pore size of the filter, the material retained on the filter includes additional particles smaller than the original pore size. The dried filters were weighed both before and after filtering and the weight gain was recorded as suspended sediment mass. The volume of the sample bottles was measured and the suspended sediment concentration was determined by dividing the weight of the sediment retained on the filter by the volume of water in the sampling bottle. The three replicate sample concentrations taken from each station were averaged to remove as much sample error as possible and to test the consistency of results from replicate samples. Results are recorded in mg/l and are shown in Appendix V. Sampling dates have been converted to cumulative days so that the time between sampling days could be more readily visualized. 63 4.3. R E S U L T S A N D DISCUSSION 4.3.1. SHOREWARD INCREASE IN SSC Suspended sediment concentrations decrease seaward with stations SI, S2, S3, S4, S5, and S6 showing typical concentrations of 50,40,30,15,10, and 5 mg/l, respectively and stations S14, S13, S12, and Sll showing typical concentrations of 45, 30, 10 and 5 mg/l, respectively (Figure 28). Upon initial examination of the higher suspended sediment concentrations on the inner bank, one may be tempted to suggest that the inner bank sediments are eroded more easily than sediments on the outer bank and therefore are the source of sediments to the outer bank. The implication of this behavior would be the eventual retreat of the mudflat and adjacent marshes because sediment was being removed and transported seaward. However, the higher SSC on the inner bank can be explained when one understands how sediments supplied from the Fraser River move headwards onto the tidal flats. The mechanics of tidally-driven sediment motion onto and across a tidal flat was postulated by Postma (1961, 1967) and van Straaten and Kuenen (1957) to be the product of "settling and scour lag" due to the change in sediment behavior from high to low tides because of tidal asymmetry. Postma stated: "Towards high tide, when the flood current velocity has decreased sufficiently, nearly all material sinks to the bottom. The sediment is not again brought into suspension by the returning ebb current before the latter has reached a velocity considerably higher than that of the flood current at the moment of deposition. In this manner the material is resuspended in a water mass, the relative position of which is farther inward than that of the water mass which carried the material during the flood." As the tide moves across the bank, the heaviest material settles out quickly and the fine-grained material is transported to the inner bank, consequently producing higher concentrations of suspended sediments in shore. This headward flux of suspended sediments due to tidal 64 asymmetry should be balanced by a seaward diffusion due to a seaward-decreasing SSC-gradient creating a dynamic equilibrium through diffusive rather than advective processes (Amos, 1995). 4.3.2. DECREASING SSC THROUGHOUT SAMPLING PERIOD In general, stations S3, S4, S5, S6, Sll, S12, and S14 show trends to decreasing concentration over the length of the survey implying that one source of sediments being supplied to the bank is diminishing throughout the survey. This suggests an additional source of sediments, other than those resuspended by waves or tidal currents, must be available and is likely the Fraser River. Water discharge in the Fraser River is low in the winter and rises rapidly in the spring in response to snowmelt then gradually declines during the summer to a low flow in the fall. The suspended sediment concentration follows this pattern but peaks slightly earlier than the discharge and drops very rapidly in the early spring as the supply of fine sediment in the Fraser River basin is exhausted (Kostaschuk et al., 1989; Church et al., 1990). This loop-shaped relation between sediment transport and water discharge occurring through a flood event has been observed in many rivers and is known as the hysteresis effect (Bogen, 1980; Church and Gilbert, 1975; Gregory and Walling, 1973; Statham, 1977; and Walling, 1974). Fraser River discharge rates for May and June, 1993 are shown in Figure 29 with peak river flow occurring on May 20, day 6 of the SSC survey. Unfortunately, suspended sediment measurements in the Fraser River at Mission were unavailable for 1993 at this time. Suspended sediment concentrations in the Fraser River should peak slightly before May 20 and should be declining by the start of the suspended sediment survey on May 14 which is the trend observed on the bank at stations S3, S4,S5,S6,Sll,S12,andS14. 66 4.3.3. INCREASE IN SSC DUE TO WIND AND WAVES Suspended sediment does not remain stable at the concentrations described above as large peaks and drops in SSC occur at all stations on the bank frequently. Peaks in SSC throughout the sampling period suggest resuspension by waves may be occurring. Suspended sediment peaks on day 29 (June 11) at all stations on Sturgeon Bank except station Sll, with values as high as 400, 150,45, 50,35,56, 190, and 224 mg/l measured at stations S2, S3, S4, S5, S6, S12, S13, and S14, respectively. The most prominent peaks on day 29 occur at stations S12 and S13 and indicate that these stations are more affected by sediment suspension through wave action. Station S12 also demonstrated a strong influence from the Fraser River discharge as described above. Station S1 was not sampled on June 11 because the water depth was not conducive for a representative sample. Hourly wind speeds on June 11 reached 35 km/hr from the west, the maximum hourly wind speed recorded in the month of June. Peak wind gusts on June 11 during the period of suspended sediment sampling reached 43 km/hr. Current speeds measured at all stations on June 11 are high however station Sll suspended sediment concentration peaked on day 1 (May 14) of the survey reaching 42 mg/l rather than day 29 suggesting that the Fraser River influence is important at this station and that tidal as well as wave particle velocities are responsible for sediment erosion here. Suspended sediments at other stations also show high concentrations on May 14 despite the relatively low wave particle velocities. Hourly wind speeds on May 14 ranged from 10 to 20 km/hr from the southeast. Suspended sediment concentrations are also noticeably high on days 15 (May 28), 18 (May 31) and 41 (June 23) when wind speeds were 20 to 24 lan/hr from the 68 east/southeast, 6 to 20 krn/hr from the west/southwest and 24 to 30 km/hr from the west, respectively. Current velocities on day 15 are similar to day 1 in that they are low at all stations relative to other suspended sediment sampling days implying that the peak in SSC on days 1 and 15 may be the result of Fraser River influence rather than resuspension by waves. These two days are characterized by winds from the east/southeast which seem to have an effect on increasing the concentration of suspended sediment without increasing current velocities over the bank. High suspended sediment concentrations measured on days 18 and 41 can be explained by high current velocities which persisted on these day relative to other SSC sampling days. Unfortunately, suspended sediment concentrations were not measured on May 11 and 12 when high current velocities were persistent. The majority of sediment in suspension on the bank is likely derived from the Fraser River discharge with a smaller amount being derived from erosion of the bank itself. However waves can strongly influence the concentration of suspended sediment on Sturgeon Bank. Suspended sediment concentrations increase considerably when wind speeds are greater than 25 krn/hr. Even lower wind speeds of longer duration do not seem to generate waves large enough to resuspend the amount of sediment that winds of higher speed and shorter duration are capable of. The greatest amount of sediment suspension is measured generally when the winds are blowing from the west where the fetch is the longest; however winds from the southeast are capable of increasing SSC if speeds are high enough. 4.3.4. LIMITATIONS OF SUSPENDED SEDIMENT CONCENTRATION DATA In order to assess the error associated with suspended sediment sampling at least 69 6 replicate samples would need to be taken and statistically analyzed. Since this was not done, sample error can only be estimated by the variability in the three replicate samples. Replicate sampling, although not statistically sufficient, indicate that the method of suspended sediment collection should be examined. Sample replicates vary in concentration by as much as 169% from the average, with most varying only 1 to 30% of the average. In many instances one of the three replicate samples accounted for the majority of the variability. When these values were removed from the data set the variability decreased dramatically in most cases. Although one cannot simply remove data, the exercise confirmed that the method of suspended sediment collection may be subject to many errors. Some of the variability in replicate sampling could be due to the variability in the water column. It is more likely, however, that the problems in bottom disturbance by the sampling vehicle, inconsistent rates of ascent and descent with the sampling instrument, seabed contact with the sampling instrument in rough conditions, and collection of particles finer than 0.045 pm on clogged filters are responsible for a large part of the sample inconsistency. It is difficult to collect suspended sediment rapidly because typical sample collection times ranged from 2 to 3 hours for 10 stations depending on the weather. This meant that sampling could not be carried out everyday because of hovercraft and human time constraints. Thus it is difficult to get a precise picture of the suspended sediment changes on a daily or even hourly time frame which would be necessary to determine the true suspended sediment dynamics on the bank. 70 Chapter 5. GRAIN SIZE ANALYSIS 5.1. FIELD SAMPLING Bulk sediment samples were taken from 56 sites on Sturgeon Bank (See Figure 4). Bulk sediment samples were also taken from the 10 Sea Carousel sites. Samples comprise the top two centimetres of sediment at each site and were collected using an 8 cm diameter plexiglass tube pushed into the exposed sediment at low tide on June 30 and July 1, 1992. Samples were collected from the Sea Carousel sites by scooping a thin veneer of sediments from the surface to a depth of approximately 2 cm on July 10, 1991. Five samples were collected at station 19 in a 10 metre east-west transect using 2 metre sample spacing to examine the variability in sediment grain size between adjacent samples. 5.2. ANALYTICAL TECHNIQUES Sediment samples were dried in an oven at 80°C overnight and disaggregated with a spatula. Dried samples were weighed and then washed through a 230 (63 pm) mesh in a process known as wet sieving to collect the sand fraction. Once washed the sand fraction was transferred to a beaker, dried in an 80°C oven, then reweighed and the weight loss recorded as mud weight. The dried sand fraction was split into 2.0 g sub-samples and then run through a settling tube with and internal diameter of 20 cm and a height of 2 m. The instrument contained a plexiglass plate suspended from a Mettler balance at the bottom of the tube. The deflection of the balance increased with accumulating weight and using Stokes law (ws = [(ps-p)g/18u]d2; where ws is the settling velocity, d the particle diameter, ps-p the density difference between the particles and the 71 fluid, and u the viscosity of the fluid) a computer calculated the particle size by correlation with time of particle descent. The sampling introduction devices consisted of two discs having a slight convexity onto which the sample was uniformly distributed and wetted with Kodak Photoflo in a method similar to that described by Gibbs (1972). The sample-loaded disc was inverted, then lowered into the top of the tube until, upon touching the water surface, surface tension was broken and the sample was released. This procedure allowed minimum disturbance of the sample upon introduction. Upon contact with the water surface a timer begins recording the time of descent of the particles. The distilled water in the settling tube was allowed to equilibrate with room temperature for several hours prior to use in order that no convection currents would disturb the settling velocities of the spheres. Two samples were run so that an average particle size could be calculated. A description of the statistical analyses and grain size results are given in Appendix VI. Samples were visually inspected for mud and those which contained more than 5% mud (silt and clay) were washed through the 230 (63 pm) mesh sieve and the wash water collected in a plastic bucket below the sieve. The wash water was transferred to half litre plastic cups and then spun in a centrifuge at 2000 R.P.M. for 90 minutes to separate the mud. The supernatant was poured off and the mud was transferred to plastic bags and freeze-dried for 2 days. Once dried, 2.5 g sub-samples of the mud were transferred into plastic sedigraph cups and the cups filled with approximately 30 ml of 0.05% sodium hexametaphosphate, an anti-coagulant which prevents particle flocculation. The mixture was then stirred, run through a sonic bath and then run through a Sedigraph® 5100 analyzer. The sedigraph determines particle size in the silt and clay range down to 14<p by using a finely collimated X-ray beam to measure particle 72 concentration in terms of transmitted intensity of the X-ray beam through the sample relative to a clear fluid. 5.3. R E S U L T S A N D DISCUSSION 5.3.1. SEDIMENT GRAIN SIZE Sediments have been classified into appropriate grain size using the Wentworth classification scheme according to their mean grain size in phi units using the first moment statistical method (See Appendix VI-1). A ternary diagram (Figure 30) demonstrates the abundance of sand and silt in the sediments collected on Sturgeon Bank. A majority of the sediments collected on the bank fall into the fine sand category (44% of the samples collected), while only 9% of the samples were fine silt, 7% were medium silt, 13% were coarse silt, 10% were very fine sand, and 17% were medium sand (Figure 31). Grain size contours drawn on Figure 31 have been constructed by hand and represent the Wentworth size classes. The medium sand samples contain 98 to 100 wt. % sand and the fine sand samples contain 93.5 to 99 wt. % sand with the remaining fraction consisting of silt-sized particles. The proportion of sand to mud reflects the amount of winnowing at the site of deposition. Mud values are defined as the sum of the silt and clay fraction in the sample. The remainder of the sediment sample collected from Sturgeon Bank that was not mud consisted of sand. Sturgeon Bank samples contain a relatively small amount of clay, consequently most of the mud fraction in the sediment is comprised of silt-sized particles. The clay content in sediments from Sturgeon Bank ranges from 0 to 26 wt. % with the highest clay content being found in sediments collected from stations 21,40, S2, S3, S13 and S14 where clay-sized particles comprise 20 wt. % or more 73 C L A Y Figure 30: Ternary diagram indicating percent sand/silt/clay for sediments on Sturgeon Bank 74 North Arm Jetty Fine silt Medium silt Coarse silt Very fine sand Fine sand Medium sand Grain size stations Sea Carousel stations Iona Jetty Vancouver International A i r P ° r t Canadian Coast Guard c hovercraft base Strait of Georgia Fraser River Middle Arm - 4 7 7 4 4 5 5 4 4 5 5 2 5 Steveston Jetty Figure 31: Sediment Grain Size on Sturgeon Bank using Wentworth classification 75 of the sample. The fine and medium sand samples collected contain no clay while all of the very fine sand samples contain minor amounts of clay. Stations 20 and 23, in particular, contain 9 wt. % clay, higher than their other very fine sand counterparts. The coarse silt sediment class contains between 10 - 15 wt. % clay and 27 to 49 wt. % silt with an anomaly in the coarse silt sediments collected from station 5 which contain 86 wt. % silt, higher than any other sediment sample collected from Sturgeon Bank in this study. 5.3.2. SEDIMENT SORTING Sediments have been classified into appropriate sorting classes using the Pettijohn et al. (1973) classification scheme modified from Folk (1968) according to their standard deviation in phi units using the second moment statistical method (See Appendix VI-1). Sorting depends on 4 major factors (Folk, 1968), (1) the size range of the material supplied to the environment, (2) the type of deposition (i.e. beach vs. river etc.), (3) the current characteristics, that is, the best sorting is obtained by currents of intermediate and constant strength as opposed to very strong, very weak or currents which fluctuate rapidly which are not efficient sorters, and (4) time, that is, the rate of supply of detritus compared to the efficiency of the sorting agent. Sorting on Sturgeon Bank varies between 0.31 (very well sorted) to 2.7 (very poorly sorted) (Figure 32). In general sediments become more well sorted in a seaward direction, however, poorly sorted sediments extend to the middle of the central bank at stations 12, 13 and S4. Very poorly sorted sediments dominate the area adjacent to the Iona jetty and the airport on central Sturgeon Bank with slightly better sorting in sediments at stations 21 and SI. On southern Sturgeon Bank, very poorly sorted sediments occupy the inner bank adjacent to the 76 North Arm Jetty Grain size stations Sea Carousel stations very poorly sorted poorly sorted moderately sorted well sorted very well sorted Iona Jetty Steveston Jetty Vancouver International Canadian Coast Guard o hovercraft base Strait of Georgia Fraser River Middle Arm 4 - 477445 5445525 Figure 32: Degree of sorting in sediments on Sturgeon Bank 77 Middle Arm and the the inner bank at stations 38, 40 and S13. Sediments adjacent to the Steveston jetty on the inner bank are well sorted unlike other sediments collected this far shoreward. Sediments collected from station 51 are only moderately sorted, unlike the well-sorted sediments collected from stations this far seaward. Sediment sorting at stations 30,31 and 36 is better than other stations on the inner bank similar to the trend seen in sediments found at stations 21 and SI on central Sturgeon Bank. Sediments collected from station 55, south of the Middle Arm show the highest degree of sorting on the bank. Sorting is strongly dependent on grain size which can be seen by constructing a scatter plot of mean size versus sorting (Figure 33). The highest degree of sorting is found in the medium sands on Sturgeon Bank and then decreases through the fine and very fine sands with the poorest sorting present in the coarse and medium silts. There is a slight increase in the degree of sorting in the fine silts. This trend in sorting values is consistent with many grain size studies and can be partially explained by nature which produces three basic populations of detrital grains to rivers and beaches (Wentworth, 1922). The first is a pebble population which results from rocks which break along joint or bedding planes. This population is not found in Sturgeon Bank sediments. The second is a sand coarse-silt population which represents the stable residual products from the weathering of granular rocks and the third is a clay population which represents the reaction products of chemical decay of unstable minerals in soil. This sorting by nature results in a scarcity of sediments in the granule to coarse sand (0 to -2(b) particles, and fine silts (6 to 8(b) particles and suggests that sediments of these sizes must be a mixture of either sand with pebbles or sand or coarse silt with clay and therefore will be more poorly sorted than the pure end members of gravel, sand, or clay. 78 5.3.3. GRAIN SIZE AND SORTING CONTROLS ON ERODIBILITY The fine-silt sediments collected from station SI have less clay than the fine-silt sediments from station S2, which is likely the reason for the higher erosion threshold at station S2. Sediments collected from stations S13 and S14, however, both have clay contents over 20% and show much lower erosion thresholds. This may be the result of higher sand contents at these two stations. It seems reasonable to say that sediments with clay contents over -20% and high silt contents are more difficult to erode than sediments with clay contents over -20% and high sand contents. Station S3 sediments show a high erosion threshold (relative to stations S13 and S14) despite the low silt and high sand content. The reason for this may be the coarser-grained nature of the sand-sized sediments. Sediments collected from station Sll contain 99% fine-sand with no clay and consequently erode easily. Fine-sand samples which contain clay require a higher surface shear stress to initiate erosion as stations S4 and S12 demonstrate. The medium-sand samples at stations S5 and S6 show similar erosion thresholds, higher than the fine-sand sediments due likely to the size and weight of the sand grains being eroded. Sediments which are poorly sorted are more difficult to erode than sediments which are well sorted. This behavior can be seen especially in the fine and medium-sand size fractions. This is not the case in the fine silts where sediments from station S1 are more difficult to erode despite the better sorting than sediments from stations S13 and S14. Station SI possesses a high surface sediment strength despite its' low clay content, high silt content, and better sorting than the other inner bank stations. It is suggested that some sort of biostabilization on the sediment 80 surface has taken place at station SI, possibly diatoms. 5.3.4. SEDIMENT GRAIN SIZE VARIABILITY Station 19 was sampled 5 times in an east-west transect with a sample spacing of 2 metres. Station 19a was the closest to the shoreward edge of the bank while station 19e was the closest to the seaward edge of the bank. All samples were classified as coarse silts with very poor sorting according to the Wentworth and Pettijohn classification schemes. Sand contents varied from 42 to 61 wt. % in the five samples with corresponding silt contents varying from 39 to 27 wt. %. In general there is an increase in sand content (decrease in silt content) in a seaward direction, however sample 19b, closer to the shore contains a higher sand content than its more seaward counterparts, 19c and 19d. Initially the 56 stations sampled for grain size were thought to behave similarly to sediments collected from the 10 Sea Carousel sites. That is, if fine sand sediments were easily eroded at station 11 then fine sand sediments should be easily eroded at other stations on the bank. However, the degree of variability in sediment grain size results within a 10 metre spacing reveals how difficult it is to extrapolate values across the bank. Grain size and their corresponding erodibility results should therefore be assumed to be site specific. 81 Chapter 6. SEDIMENT GEOCHEMISTRY 6.1. FIELD SAMPLING Bulk sediment samples were taken from 56 sites on Sturgeon Bank (see Figure 4). The sites corresponded with the grain size sampling stations and geochemical analyses were performed on the same sediment sample as grain size determination. Samples comprise the top two centimetres of sediment at each site and were collected using an 8 cm diameter plexiglass tube pushed into the exposed sediment at low tide on June 30 and July 1, 1992. Five samples were collected at station 19 in a 10 metre east-west transect using 2 metre sample spacing to examine the variability in sediment geochemistry between adjacent samples. 6.2. ANALYTICAL TECHNIQUES Sediment samples were dried in an oven at 60° overnight and then ground in a tungsten carbide mill for two minutes. Ground samples were analyzed for major and minor element concentration, inorganic and total carbon content, and nitrogen content. Major element compositions were determined on fused glass discs using X-ray fluorescence following Norrish and Hutton (1969) and are reported as wt.% abundance of the element. Minor element compositions were determined on pressed powder pellets using X-ray fluorescence and reported as parts per million (ppm). Total carbon and nitrogen were determined by gas chromatography/thermal conductivity on a Carlo-Erba CNS analyzer (model NA-1500) and carbonate carbon (inorganic carbon) was determined by coulometry. Details of major and minor element analyses, a description of X-ray fluorescence spectrometry, total carbon and nitrogen 82 analyses, inorganic carbon analyses, major and minor element results, XRF instrument settings, analytical precision and accuracy of all analyses, and carbon/nitrogen analyses are given in Appendix VH - 1, 2, 3,4, 5, 6, 7, 8, 9, 10, 11, 12, and 13, respectively. 6.3. RESULTS AND DISCUSSION 6.3.1. CONTROLLING FACTORS ON THE COMPOSITION OF SEDIMENTS Nearshore sediments vary widely in mineralogical composition mainly because they are deposited in environments where physical conditions are continually changing. Sediments are composed of three main components which are detrital, authigenic and biogenous in origin (Calvert, 1976). Detrital components are rocks fragments and minerals derived from the land through geochemical weathering which are subsequently deposited via rivers, ice, or wind. These include insoluble primary minerals and new minerals formed in the weathering environment, principally clays and oxides of iron and aluminum. Authigenic components are those derived from inorganic precipitates which form both in the water and after deposition of the bulk sediment through diagenesis. Biogenous components are those derived from skeletal remains including carbonate, silica and phosphate and the degradation of organic material, including humic materials and other insoluble organics. The elemental composition of a sediment is determined by the influence of each of these components whose proportions can vary widely. On the west coast of Canada the detrital component dominates due to the high precipitation, high relief and (because most of Canada has been glaciated in recent geological history), the large amount of glacial flour produced by the abrasion of bedrock. Textural control also plays a major role in the elemental makeup of a given sediment and 83 therefore cannot be overlooked in any geochemical study. Certain elements are enriched in coarser (sand and silt) fractions while others are concentrated in the finer portions (mud and clay) (Calvert, 1976). Therefore, regional comparisons of elemental concentrations can only be made using texturally equivalent sediment size fractions (Loring and Rantala, 1992; Calvert, 1976). Sediments offer many sites and possibilities for metal associations. Metals may exist as constituent elements present in the insoluble primary minerals produced by physical weathering, also known as the lattice-bound elements. The degree to which minor elements, including trace metals, are incorporated into detrital minerals depends on their ability to substitute for the major ions (i.e. similar ionic radii) in the crystal lattices of the principal rock-forming mineral. Metals may also exist in a variety of secondary forms such as adsorbed on surfaces (coprecipitated with iron and manganese oxides; clays; humic floes (Francois, 1987)); associated with organic matter (Troup and Bricker, 1975; Carpenter et al., 1975) as a result of either uptake by the living organism or by complexation and chelation; associated with authigenic sulfides in ion-exchange processes during the weathering of clay minerals; in the lattice positions in secondary minerals or in amorphous iron or manganese oxides (Campbell et al., 1988). Most minor elements show an affinity for fine-grained sediments (Krauskopf, 1979). The surface area of the particles making up the sediments increases with decreasing grain size and therefore, the minor elements being hosted within these minerals will tend to be enriched in the fine-grained material. Organic material and fine-grained sediments tend to be deposited together in low energy environments (Kuenen, 1965; Calvert, 1983). This is because of the adsorptive affinity of fine-grained material for certain organic compounds during deposition (Premuzic, et al., 1982) and the low-density nature of organic debris which allows it to behave hydraulically 84 equivalent to clay or fine silt sized detritus. A major source of sediment on the Fraser delta is Pleistocene glacial deposits from the interior of British Columbia (Pharo, 1972). Geochemical analyses in deltaic sediments from Sturgeon Bank have been discussed by Grieve (1977); Grieve and Fletcher (1976); B.C. Research (1973, 1975, 1977); Birtwell et al., (1983) Coastline Environmental Services Ltd. (1985) and provide the most extensive data collected to date. Grieve and Fletcher's (1976) work discovered a close correlation between trace-metal concentrations, sediment texture, and Fe and Mn content. Their studies also indicated that within the sediments, the bulk of the trace metals are present in a non-labile form associated with the detrital silicate minerals and 10-20% are associated with hydrous oxides of Fe (and Mn) which form coatings on detrital grains. The authors concluded that the dominant controls on trace-metal distribution patterns on the delta-front and upper fore-slope were the physical processes influencing sediment transport and size-fractions distributions. All studies on the geochemistry of sediments on Sturgeon Bank found abnormally high concentrations of labile trace metals in sediments adjacent to the Iona sewage treatment plant where discharge of metal rich sewage took place from 1962 until 1988. Unfortunately, results of the sediment geochemical studies to date have been determined using a variety of analytical methods and therefore caution should be exercised when comparing results. Total element analyses are easier to compare than analyses which extract only a certain component of the minor elements (i.e. the labile component) unless the analytical techniques are the same. It is however, more difficult to determine what is biologically available to organisms using the total element analytical method. 85 6.3.2. MAJOR ELEMENTS 6.3.2.1. Aluminum Feldspars, micas, pyroxenes and amphiboles are important Al-bearing minerals (Rankama and Sahama, 1950). The distribution of Al in sediments likely reflects the distribution of fine-grained material associated with the minerals described above. The Al% content in sediments on Sturgeon Bank ranges from 5.0 to 7.2 ± 1.05% by weight with the highest concentrations in the fine silt-rich sediments at stations 21 and 40 (Figure 34). The lowest concentrations were found on outer southern Sturgeon Bank, stations 33,44 and on a small area north of the middle Arm at station 16. Aluminum correlates negatively with grain size (r = -0.77) (Figure 35) indicating concentration in the finer size fraction; it is therefore a reasonable proxy for grain size. 6.3.2.2. Silicon The distribution of silica in sediments likely reflects the distribution of quartz, a resistant mineral left after weathering that dominates the sand and silt size ranges. It tends to be found in the coarser fractions of sediments and to accumulate in turbulent depositipnal environments where finer-grained sediment constituents such as clay minerals and organic matter are resuspended (Rankama and Sahama, 1950). The content of silicon in surface sediments from Sturgeon Bank varies from 29.7 to 36.9 wt. % ± 0.85% (Figure 36). These values are up to twice those obtained from sediments in Howe Sound (Drysdale, 1990) and could reflect the differing grain sizes present in these environments. The highest concentrations for this study were found on outer Sturgeon Bank, in particular at station 54 in the medium sand size fraction, and at stations 48 and 35. The lowest concentrations were found at stations 21 and 40. This 86 f N North Arm Jetty Grain size stations Sea Carousel stations - 7.0 wt. % • 6.5 wt. % 6.0 wt. % 5.5 wt. % Iona Jetty Iona Sewage " 3 5 Treatment Plant Strait of Georgia -+ 477445 5445525 I 479274 Steveston Jetty 5440039 A i r P ° r t Canadian Coast Guard hovercraft base Fraser River Middle Arm Figure 34. Areal distribution of aluminum content on Sturgeon Bank 87 It) E c 'E < in co in ui C £ c o o E c 'E 'w C 'c3 u. 6 0 3 oc CJ > C c o CJ s s < 3 3 m co 3 in sijun jqd u; azis urejQ 88 North Arm Jetty Grain size stations Sea Carousel stations 37.0 wt. % 36.0 wt. % 35.0 wt. % 34.0 wt. % 33.0 wt. % 32.0 wt. % 31.0 wt. % 30.0 wt. % Iona Jetty Iona Sewage Treatment Plant Strait of Georgia -+ 477445 5445525 479274 Steveston Jetty 544€f039 Vancouver International A i r P ° r t Canadian Coast Guard hovercraft base Fraser River Middle Arm Figure 36: Areal distribution of silicon content on Sturgeon Bank 89 distribution shows the opposite trend to Al, as expected, because Si is more enriched in the coarser-grained sediments. Silica correlates positively with grain size (r = +0.87) (Figure 37) and is indicative of quartz enrichment in the sand and coarse silt size fractions. The variation of elemental concentrations in sediments does not necessarily reflect the input of certain minerals, since varying degrees of dilution by other components may be operating (Calvert, 1976). In order to avoid misinterpretation of data caused by these effects, ratios of one element to another are commonly used rather than the absolute abundance of an element. Aluminum is often used to normalize element concentrations because it is an element essentially exclusive to silicate minerals. In this way it can be used to determine whether changes in elemental concentrations represent changes in mineralogy of the source rocks or whether they are due simply to dilution by other materials. The areal distribution of the Si/Al ratio varies from 4.11 to 7.13 with the highest values occurring on the outer bank of central and southern Sturgeon Bank and the lowest values occurring at stations 21 and 40 (Figure 38). These ratios are higher than those obtained by Drysdale (1990) in Howe Sound sediments and Francois (1987) in Saanich Inlet sediments. 6.3.2.3. Titanium The concentration of titanium in sediments on Sturgeon Bank ranges from 0.2 to 0.7 wt.% ± 0.85% (Figure 39). The highest values occur on the inner bank and at station 14. The highest content was found at station 36 with a noticeable difference in Ti content between stations 40 and 41, 510 metres apart. The grain size difference between these two stations is likely the cause of such wide variation as station 40 is composed of fine silt and station 41 is composed of medium 90 r- co in T T m C M T - O s\\ur\ jLjd in ez;s IUBJQ 91 -479274 Steveston Jetty 5440039 Figure 3 8 : Areal distribution of S i / A l on Sturgeon Bank 9 2 North Arm Jetty Grain size stations Sea Carousel stations 0.65 wt. % 0.60 wt. % 0.55 wt. % 0.50 wt. % 0.45 wt. % 0.40 wt. % 0.35 wt. % 0.30 wt. % 0.25 wt. % Iona Sewage Treatment Plant Vancouver International A i r P ° r t Canadian Coast Guard hovercraft base Strait of Georgia Fraser River Middle Arm 4 4 7 7 4 4 5 5445525 Figure 39: Areal distribution of titanium content on Sturgeon Bank 93 sand. Titanium may occur in marine sediments as ilmenite (FeTi03), rutile (TiO ,^ anatase (TiOj) or brookite (Ti02) which are refractory oxides concentrated in the sand fraction, as finely disseminated cryptocrystalline rutile which adsorbs to clay minerals in the finer fraction, or substituting for Al in clay minerals (Rankama and Sahama, 1950; Degens, 1965). The distribution of Ti/Al reflects the distribution of Ti with the highest ratios present in sediments from stations 14, 28, 30, 36 and 38 (Figure 40). Titanium correlates only reasonably positively with grain size (r= +0.44) (Figure 41a) suggesting that the element is concentrated in the fine to very fine sand fraction of sediments on the bank. Medium sand-dominated sediments show Ti contents generally less than 0.5 wt. %. In contrast, titanium shows a positive correlation with iron (r = +0.89) (Figure 41b) indicating that Ti-content may be largely due to the iron-bearing clay mineral phase associated with ilmenite. However ilmenite is likely only present as a trace constituent and therefore the host for Ti in Fe-bearing minerals is not known. 6.3.2.4. Iron Iron occurs in detrital sediments in illite, ferro-magnesian micas, amphiboles (general formula: W0.1X2Y5Z8O22(OH)2, pyroxenes (general formula: XYSiPg) (where W cations include Na and K, X cations include Ca, Mg, Fe and Y cations include Mg, Fe, Al), some K-feldspars, and in the authigenic mineral glauconite [(K,Na)(Fe3+,Al,Fe2+,Mg)2(Si,Al)4O10(OH)2] (Rankama and Sahama, 1950). Dissolved Fe usually flocculates as it passes from fresh into saline waters (by ~ 15%o) where it is then incorporated into hydroxide and oxyhydroxide coatings on mineral particles (Burton and Liss, 1970). The most common hydroxide and oxyhydroxide phases in oxic 94 4 N North A rm Jetty Y \ G r a i n size stat ions • S e a C a r o u s e l stat ions Fraser River North Arm cosV 53 0 . 1 1 5 ! 1 \ 0 . 1 0 5 \ 0 . 0 9 5 \ 0 . 0 8 5 \ vi a o 5 ° 4 \ V 2 / 0 . 0 7 5 0 .065 0 .055 0 .045 0.05 :6 / / 0 I ona Jetty - 0 0 5 57^ 9C - 0.07 I9D-0.07 S/ra/Y of Georgia - ( -477445 5 4 4 5 5 2 5 /H-479274 S teveston Jetty £>44©u39 km Iona Sewage f PFant = a 7 2 0 *S1 Vancouver International |f* 1 A i r p o r t Canadian Coast Guard hovercraft base Fraser River Middle Arm Figure 40: Areal distribution of T i / A l on Sturgeon Bank 95 Titanium sediments are hematite (Fe203), geothite (aFeO(OH)) and lepidocrocite (YFeO(OH)) (Degens, 1965) while the most common hosts in anoxic sediments are pyrite (FeS2) and siderite (FeC03) (Krauskopf, 1979). Iron concentrations in the sediments on Sturgeon Bank range from 2.3 to 4.3 wt.% ± 3.4%, are highest at stations 21 and 40 and other stations on the inner bank, and decrease in concentration seaward (Figure 42). Sediments collected from stations 15 and 16 contain considerably less Fe than others in the same area. The plot of Fe/Al ratios in surface sediments show values ranging from 0.42 to 0.77 (Figure 43). Ratios on northern Sturgeon Bank are highest on the inner bank but lower concentrations are found adjacent to the north arm jetty but then increase seaward. Sediments on the central bank show Fe/Al ratios which increase seawards with the exception of station 20 where low values were found and station 14 where high values were found. Southern Sturgeon Bank sediments show a similar trend to those on the northern and central banks with the addition of local highs in Fe/Al ratio located at stations 28 and 36. Iron shows good positive correlation with grain size (r= +0.60) with the highest concentrations generally occurring in the finest grained sediments (Figure 44a). There is, however, a significant addition of coarser grained sediments with high Fe contents such as station 45 (medium sand), stations 14, 28, 32 and 42 (fine sand) and stations 23, 30 and 36 (very fine sand). The high Fe content in some fine sands may be the result of some Fe-bearing sand-sized material such as the mineral pyrite (FeSj) or more likely the mineral magnetite (Fe304). Chlorite [(Mg,Al,Fe)3(Si,Al)4O10(OH)2(Mg,Al,Fe)3(OH)6] is likely associated with the coarsest-grained clay-sized sediment and therefore the higher Fe in some coarse silts and very fine sands may be due to the presence of Fe-rich chlorite which is common in the Fraser River sediments (Pharo, 97 North Arm Jetty v \ Fraser River Grain size stations V North Arm 1479274 Steveston Jetty 5440039 Figure 42: Areal distribution of iron content on Sturgeon Bank 98 North Arm Jetty Grain size stations Sea Carousel stations 0 . 4 8\: 53 Fraser River North Arm N 0.75 0.70 0.65 0.60 — 0.55 0.50 0.45 Iona Sewage —^15 L_U Treatment Plant Iona Jetty 0.49 57 = 0.53 20 -Sli -18 t19 -,5 2 I 19A - 0.59 } 19B- 0.56 / 19C-0.57 19D-0.58 19E-0.59 Strait of Georgia Vancouver International ^=^P 6Vf 1 A i r p o r t Canadian Coast Guard hovercraft base Fraser River Middle Arm -f-47 7445 5445525 _ 47-9274 Steveston Jetty 5440039 Fraser River Main Arm Figure 4 3 : Areal distribution of F e / A l on Sturgeon Bank 99 Iron Figure 44: (a) Iron content versus grain size (b) Iron content versus magnesium content 100 1972). Iron-rich sediments could therefore be indicative of Fraser River source material. The observation that chlorite may be responsible for a large part of the iron content found on Sturgeon Bank is consistent with the positive correlation between Fe and Mg (r= +0.80) shown in Figure 44b. The Fe and Mg correlation may also be due to biotite-vermiculite [K2(Mg,Fe)3AlSi3010(OH,0,F)2]-[(Mg,Ca)(Mg,Fe2+)5(Fe3+,Al)(Si5,Al3)02o(OH)4-8H20] or hornblende [(Na,K)0.1Ca2(Mg,Fe2+,Fe3+,Al)5(Si,Al)8O22(OH)2]; however, iron and potassium correlate poorly (r= +0.38) and indicate that the influence from Fe-K minerals (eg. biotite) is negligible. The strong correlation between Fe and Mg indicates that most of the iron present on Sturgeon Bank is associated in lattice-bound form rather than as oxides and therefore is not likely biologically available to organisms. 6.3.3. CARBON AND NITROGEN Primary production in estuaries contributes organic carbon to the environment along with contributions from terrestrial drainage and anthropogenic activity in and around the estuary. The distribution of organic carbon in Sturgeon Bank sediments is shown in Figure 45. High values (> 0.5% ± 4.84 % by weight) are found at stations 5, 17,18,19, 21 and 40 with stations 3,12, 13, 16, 20, 23, 45, 26, 27, and 31 also demonstrating C o r g enrichments. The highest Co r g value was found at station 21 (1.11%) adjacent to the once active Iona sewage outfall. All other stations on the bank have C o r g contents of less than 0.2% by weight. These values are fairly typical of many nearshore estuarine environments (for example, Calvert, 1976; Krom and Sholokovitz, 1977; Rosenfeld, 1979; Francois, 1987; McNichol et al., 1988 and Drysdale, 1990) which have high marine productivity and/or high terrigenous inputs. 101 North Arm Jetty ° Grain size stations • Sea Carousel stations — 1.0 wt. % — 0.8 wt. % — 0.6 wt. % — 0.4 wt. % 0.2 wt. % Fraser River North Arm km Iona Sewage Treatment Plant Iona Jetty Strait of Georgia + 477445 5445525 ! Vancouver International i 5 '-'Y7 1 A i r p o r t Canadian Coast Guard •— hovercraft base Fraser River Middle Arm \ ^ 3 X x . -~-±'--._. o.i8, 39 Q34 38 5 6 C ? . S 1 1 48° 4 - S 1 2 ; , . L ° ' I % 4 0 4 6 0 1 6 45 42 L--- -4VV 0.14-52 0 1 2 - 5 0 Fraser River ° i * 5 i / Main Arm I 479274 Steveston Jetty 5440039 A Figure 45: Areal distribution of organic carbon on Sturgeon Bank 102 The positive correlation between C o r g and grain size is very good (r = +0.88) showing a decrease in grain size with a corresponding increase in C o r g (Figure 46) confirming that hydraulic sorting plays a major role in determining the organic carbon content and explaining the preferential accumulation of organic carbon in fine-grained sediments. It is clear then that textural controls dominate the content of organic carbon on the bank but the composition of organic carbon depends on its source. Corg/N ratios for terrestrial material are generally higher (> 15) because terrestrial material (leaves, bark etc.) contain less nitrogen than marine plankton (Corg/N ~ 6). Q g /N ratios are therefore used as an index of the relative contributions of marine and terrestrial material (Borodowskiy, 1965; Miiller, 1977). Organic carbon/nitrogen ratios in Sturgeon Bank sediments range from 4.9 at station 44 to 13.6 at station 5 (Figure 47). The highest Corg/N ratios occur in the coarse silt-dominated fraction. The highest C o r g value was found at station 21 and is accompanied by a Corg/N value of 8.71 whereas lower C o r g contents at stations 5, 17, 26, and 40, have C0Ig/N ratios greater than 11. These results indicate that high Co r g, low Corg/N sediments found at station 21 and stations adjacent to the once active Iona outfall are potentially more reactive than fine-grained sediments elsewhere on the bank. 6.3.4. MINOR ELEMENTS Minor elements occur in concentrations of a few tenths of a percent or less by weight (Richardson and McSween, 1989) and their geochemistry is affected by changes in temperature, salinity, pH and redox potential of the waters that surround them (Troup and Bricker, 1975). Therefore minor elements participate in a variety of biogeochemical reactions in the water and 103 Grain size in phi units I—' • CTQ C O trq O 0 1 O S3 O o S3 c-t-S3 r-^  < CD i-t c CTQ »-l B. S3 N C Q 0) o" O CU —T cr o O o CD 3 North Arm Jetty Grain size stations Sea Carousel stations - 13.0 12.0 - 11.0 - 10.0 - 9.0 - 8.0 - 7.0 6.0 5.0 Iona Jetty Iona Sewaae Treatment Plant Strait of Georgia + 477445 5445525 Vancouver International A i r P ° r t Canad ian Coast Guard hovercraft base Fraser River Middle Arm /'+479274 Steveston Jetty 5440039 V Figure 47: Areal distribution of C(org)/N on Sturgeon Bank 105 sediments unlike most major elements which behave nearly conservatively (Troup and Bricker, 1975). The concentrations of minor elements in sediments depends in part on their ability to substitute for the major ions in the crystal lattices of principal minerals (Krauskopf, 1979). 6.3.4.1. Cobalt Cobalt is a transition metal with an ionic radius similar to Fe and Mg and therefore it substitutes for these major elements in the crystal lattices of early-forming Fe and Mg minerals of ultramafic rocks (olivine and pyroxene groups) and some basalts (Rankama and Sahama, 1950). Cobalt forms no independent minerals in igneous rocks; however it substitutes for iron in the pyrite and sphalerite structures forming minerals like CoS2 (cattierite), Co3S4 (linnaeite; 51% Co), CoAsS (cobaltite; 35.4%Co) and CoAs3.2 (smaltite; ~ 28% Co) (Rankama and Sahama, 1950). The bulk of cobalt found in igneous rocks is incorporated in silicate minerals. The elemental abundance of Co in sediments on Sturgeon Bank ranges from 40 ppm to 138 ppm ± 28.86% (Figure 48), significantly higher than values found in Howe Sound sediments (Drysdale, 1990) and in reported values for shales, sandstones and sediments (Mason and Moore, 1982). Cobalt is enriched in sediments from stations 5, 12, 20, 25, 29, 30, 48 and 52 with stations 4, 18 and 22 showing the highest concentrations. The plot of Co/Al distribution in surface sediments show high local values at stations 4, 12, 18, 20,22, 25, 29, 30,48 and 52 with highest values found at stations 4 and 22 (Figure 49). The Co vs. grain size plot shows no correlation; however it does illustrate that the fine silt sediments contain the lowest Co contents (Figure 50a). The coarse silt sediments have Co concentrations ranging from 32 to 138 ppm covering almost the entire range of Co content found 106 * N North Arm Jetty Grain size stations • Sea Carousel stations — 1 2 5 p p m — 100 p p m 75 p p m 50 p p m - I X Fraser River North Arm Iona Sewage Treatment Plant Iona Jetty Strait of Georgia 4 4 7 7 4 4 5 5445525 Canadian Coast Guard hovercraft base Fraser River : Middle Arm +479274 Steveston Jetty 5440TJ39 Figure 48: Areal distribution of cobalt content on Sturgeon Bank 107 North Arm Jetty Grain size stations • Sea Carousel stations — 20.0 ppm/wt.% — 15.0 ppm/wt.% — 10.0 ppm/wt.% 5.0 ppm/wt.% Fraser River North Arm km Iona Sewage 6 7 5 Treatment Plant Iona Jetty Strait of Georgia -+ 477445 5445525 ^79274 Steveston Jetty 5440039 t N Vancouver International i s ^ i y A i f P ° r t Canad ian Coast Guard hovercraft base Fraser River Middle Arm Figure 4 9 : Areal distribution of C o / A l on Sturgeon Bank 1 0 8 Cobalt Q. C CD J2 N c w 5 c 'CO o a • • y = 0.0012x + 3.067^^ ^ ( J ? * ^ •' R' = 0.0005 22 42 62 82 102 Cobalt content (ppm) 122 142 E ^ - "5 1-5 co _ I- 1 0.5 ^ ° 0 o 0 y = 0.0003x +1.1948 R2 = 0.0007 22 42 62 82 102 Cobalt content (ppm) 122 142 C CD I * o y = -0.0009X + 3.2525 R2 = 0.0015 22 42 62 82 102 Cobalt content (ppm) 122 142 O _ 1-2 •e ^  1 8 - 0 8 _ g 0 6 C * i 0.4 CO CD O 0.2 + y = 0.0002x + 0.2561 • Rz = 0.000^  - • • 22 42 62 82 102 Cobalt content (ppm) 122 142 Figure 50: (a) Cobalt content versus grain size (b) Cobalt content versus magnesium content (c) Cobalt content versus iron content (d) Cobalt content versus organic carbon content 109 in sediments on Sturgeon Bank. Cobalt content in medium sands is generally in the 40 to 60 ppm range with the exception of station 4 where Co content reaches 132 ppm. No correlation between Co vs. Mg (Figure 50b), Co vs. Fe (Figure 50c) or Co vs. C o r g (Figure 50d) exists indicating that there is no association of Co with specific mafic minerals or organic matter. The absence of cobalt association with major or minor elements, organic carbon or grain size implies that the source of Co on Sturgeon Bank is unknown. The availability of high concentrations of Co to organisms using the bank would require further investigation. 6.3.4.2. Chromium Chromium, like cobalt substitutes for Mg and Fe in early-crystallized olivine rocks or dunites (Rankama and Sahama, 1950). In igneous rocks chromium occurs both in oxide and in silicate minerals. The only independent chromium minerals are the chromian members of the spinel group, magnesiochromite, MgCr204 and chromite, FeCr204 (Rankama and Sahama, 1950). Chromium abundance in sediments on Sturgeon Bank ranges from 54 to 216 ppm ±7.45% (Figure 51), considerably higher than values found in igneous rocks (Mason and Moore, 1982) and in Howe Sound sediments (Drysdale, 1990). The Cr vs. Al areal distribution plot (Figure 52) shows a similar trend to the Cr-content plot with high Cr/Al ratios found at stations 14, 28 and 36. High Cr concentrations are not consistent with any particular grain sizes (r = +0.16) (Figure 53a). Like cobalt, chromium is carried in the fine to very fine sand and coarse silts. Chromium correlates reasonably well with Mg (r = +0.41) (Figure 53b) and Fe (r = +0.70) (Figure 53c) implying chromium substitution for Fe and Mg in mafic minerals. Earlier 110 North Arm Jetty Grain size stations • Sea Carousel stations — 200 ppm — 175 ppm — 150 ppm — 175 p p m — 100 ppm — 75 ppm Iona Jetty Strait of Georgia + 477445 5445525 Steveston Jetty 5440039 if Vancouver International A i r P ° r t Canadian Coast Guard hovercraft base Fraser River Middle Arm 179274 Figure 51: Areal distribution of chromium content on Sturgeon Bank 111 * N North Arm Jetty Grain size stations • Sea Carousel stations — 40.0 ppm/wt.% 35.0 ppm/wt.% — 30.0 ppm/wt.% — 25.0 ppm/wt.% — 20.0 ppm/wt.% 15.0 ppm/wt.% Iona Jetty Iona Sewage Treatment Plant Strait of Georgia + 477445 5445525 +479274 Steveston Jetty 54,40039 Canadian Coast Guard hovercraft base Fraser River Middle Arm Figure 52: Areal distribution o f C r / A l on Sturgeon Bank 112 Chromium to c 3 Q . c CD N W c 2 O y = 0.0144x + 1.395 52 102 152 202 252 Chromium content (ppm) 1.8 1 1-6 C 1-4 ° 1 2 E ^ 1 . 3 -S 0.8 CO „ _ CD 0.6 O) 0.4 ^ 0.2 + 0 y = 0.0039X + 0.7433 R2 = 0.408 52 102 152 Chromium content (ppm) 202 252 C £ "E o o 4.5 4 3.5 3 + 2.5 2 + 1.5 1 0.5 0 y = 0.0122x +1.7336 R2 = 0.6975 52 102 152 202 Chromium content (ppm) 252 Figure 53: (a) Chromium content versus grain size (b) Chromium content versus magnesium content (c) Chromium content versus iron content 113 suggestions that the Mg-Fe phase in the fine to very fine sand phases may be chlorite supports the substitution of Cr for Fe and Mg in these coarser grained sediments. Chromite may also be the host for Cr in these coarser-grained sediments, however like ilmenite, it is a trace constituent and therefore unlikely to be a significant source of Cr on the bank. Both the chlorite and chromite are probably finer grained than the sand they are travelling with but because of hydraulic equivalence are concentrated in this size fraction at some stations. 6.3.4.3. Nickel Like chromium and cobalt, the distribution of Ni in igneous rocks is closely related to the distribution of Mg and Fe (Krauskopf, 1979). The nickel ion has essentially the same radius and the same charge as magnesium and consequently may be substituting in magnesium minerals. The bulk of Ni found in igneous rocks is incorporated in silicate minerals. Nickel abundance in Sturgeon Bank sediments is highest on the inner bank, decreases seaward and ranges from 26 to 51 ppm ± 7.2% (Figure 54). Nickel vs. aluminum distribution plots show higher values at stations 14, 23, 28, 36 and 38 (Figure 55), similar to the chromium distribution. The high Ni content in sediments collected from station 40 is not reflected in the Ni/Al value because of the high Al content found at this site. The Ni vs. grain size plot shows a stronger positive correlation (r=0.58) (Figure 56a) than chromium and shows that the Ni is concentrated in the finer size fraction of sediments rather than the coarser fraction where Cr and Co are found. Nickel and chromium are known to behave similarly (Krauskopf, 1979). Nickel shows positive correlations with Mg (r = +0.75) (Figure 56b) and Fe (r = +0.83) (Figure 56c) and indicates that Mg and Fe minerals are likely hosts for 114 North A r m Jetty Fraser River North Arm Grain size stations • Sea Carousel stations — 50.0 p p m — 45.0 p p m — 40.0 p p m — 35.0 p p m 30.0 p p m Iona Jetty Strait of Georgia * N km Iona Sewage 5 Treatment Plant 19A-458 7 ^ ' 19C-42.1 19D-40.9 19E • 35.0 Vancouver International %C1 A i r p o r t Canad ian Coast Guard hovercraft base Fraser River Middle Arm —J-47 7445 5445525 479274 Steveston Jetty 5440039 Figure 54: Areal distribution of nickel content on Sturgeon Bank 115 A N North Arm Jetty Grain size stations • Sea Carousel stations 8.0 ppm/wt.% 7.0 ppm/wt.% 6.0 ppm/wt.% 5.0 ppm/wt.% Iona Jetty Strait of Georgia -+477445 5445525 '13 22 Vancouver International RJsS*5Q A i r P ° r t Canadian _ Coast Guard hovercraft base Fraser River 26 Middle Arm 24J 'SI 4 V 28( 2 * V/3C 6 4 52 " 50 "-51 / ^ Fraser River Main Arm + 479274 Steveston Jetty 5440039 A y Figure 5 5 : Areal distribution of N i / A l on Sturgeon Bank 1 1 6 Nickel Q. C CD « N ~ CO c CD 7 6 5 4 + 3 2 1 0 22 E * co CD ^ c c 0.5 s § 0 o 0 1.5 1 22 CD O C P 5 4 3 + 2 1 0 22 y = 0.1601x- 2.8601 FT = 0.5791 27 32 37 42 47 52 Nickel content (ppm) y = 0.0318x +0.0257 R2 = 0.7528 27 —I— 32 —I— 37 42 47 52 Nickel content (ppm) y = 0.0794X + 0.2325 R2 = 0.8271 27 32 37 42 47 52 Nickel content (ppm) c o J Q 03 0 g 'c CO 01 o 1.2 1 0.8 + 0.6 0.4 0.2 0 22 y = 0.0232x-0.5915 32 37 42 Nickel content (ppm) 52 Figure 56: (a) Nickel content versus grain size (b) Nickel content versus magnesium content (c) Nickel content versus iron content (d) Nickel content versus organic carbon content 117 Ni where they are concentrated in the finer fraction. Correlation between Ni and C o r g (r = +0.44) (Figure 56d) indicates that some of the Ni content in the sediments may be hosted by organic material supporting the observation that Ni preferentially accumulates in the finer size fractions. 6.3.4.4. Vanadium Vanadium is strongly enriched in basic rocks and often correlates closely with Fe and Mg (Krauskopf, 1979). Vanadium is enriched in early-formed magnetite (Fe304) but also occurs in pyroxenes, amphiboles, and biotite (Mason and Moore, 1982). In general, vanadium concentrations decrease in a seaward direction and range from 83 to 144 ppm ± 9.6% (Figure 57). The V vs. Al distribution shows highest values in sediments from stations 14, 28, 36, 42 and 44 (Figure 58), similar to Cr and Ni distributions. The low V content in sediments from stations 20 and 41 and the high V content in sediments from stations 21 and 23 are not reflected in the V/Al distribution. The V vs. grain size plot shows positive correlation (r = +0.50) with V being enriched in some very fine, fine and medium sands (Figure 59a). A plot of V vs. Fe shows a very strong positive correlation (r = +0.94) (Figure 59b) and indicates that V is substituting for Fe in Fe-minerals, probably biotite or chlorite in the finer grained material but also magnetite and chlorite in the finer sand material. The relatively low abundance of V and its strong correlation with Fe implies that its presence in Sturgeon Bank surface sediments can be explained by textural effects rather than the result of previous sewage discharge. The low V content adjacent to the Iona sewage treatment plant indicates that surface sediments are relatively uncontaminated with respect to vanadium supporting the observation that V distribution is texturally-controlled. 118 North Arm Jetty S Grain size stations Sea Carousel stations — 140 p p m — 130 p p m — 120 p p m — 110 p p m — 100 p p m 90 p p m Iona Jetty Strait of Georgia + 477445 5445525 -479274 Steveston Jetty 5440039 Vancouver International A i r P ° r t Canadian Coast Guard hovercraft base Fraser River Middle Arm Figure 57: Areal distribution of vanadium content on Sturgeon Bank 119 North Arm Jetty » Grain size stations • Sea Carousel stations 26.0ppm/wt.% 24.0 ppm/wt.% 22.0 ppm/wt.% 20.0 ppm/wt.% 18.0 ppm/wt.% 16.0 ppm/wt.% Iona Jetty Iona Sewage • ey-3 •« 5 .Treatment Plant 19.3. 20 «S1 \ - 99 . • CO i l 'A-20 .3 _ r j l i ,- .10 I 198-19.3 r*>\ I n T \ / 19E-20.8 1«* 21J " • S 5 / 7 ^ X l 3 \ ^22 Strait of Georgia Vancouver International 1 A i r P ° r t Canadian Coast Guard hovercraft base Fraser River Middle Arm + 477445 5445525 / J J 7 9 2 7 4 Steveston Jetty 54^0039 Figure 58: Areal distribution of V / A l on Sturgeon Bank 120 Vanadium Figure 59: (a) Vanadium content versus grain size (b) Vanadium content versus iron content 121 6.3.4.5. Manganese Manganese behaves in a complex manner geochemically and therefore its distribution in sediments is difficult to interpret. Manganese can be partitioned into several terrigenous, biogenous and hydrogenous phases. Mn has a similar ionic radius to Fe and therefore substitutes into early-formed mafic minerals (Krauskopf, 1979) where it is enriched in biotite and hornblende but depleted in feldspars, micas and apatite (Mason and Moore, 1982). Mn is also found to form silicates, sulphides, carbonates and oxides. In addition to the difficulty in deciphering what phase Mn is present in, it also has a complex diagenetic behaviour. Mn-oxides are reduced just below the oxic zone in sediments and the dissolved Mn2+ which is formed migrates upwards towards lower concentrations until it comes in contact with oxygen where it repreciptates as amorphous Mn oxides. This typically creates manganese enrichment at the base of the oxic zone in the sediments. Such enrichments can occur within millimetres of the sediment-water interface and therefore this diagenetic behavior must be taken into consideration when interpreting Mn distribution in sediments. Samples collected from Sturgeon Bank contain the top 2 cm of sediment and do not indicate the presence of any high-Mn layers formed diagenetically. Manganese concentrations range from 472 to 975 ppm ± 6.4% and show a random distribution on the bank (Figure 60). On northern Sturgeon Bank, the concentration is lowest shoreward and increases in a seaward direction toward the highest Mn contents found at stations 1 and 7, while on the central bank Mn concentrations are lowest adjacent to the Iona jetty and increase in a southerly direction. On southern Sturgeon Bank, Mn content is lowest in a strip along the inner bank which extends from Steveston jetty northward and then heads seaward at station 49. Higher Mn contents were found 122 North Arm Jetty Grain size stations • Sea Carousel stations — 900 ppm — 800 ppm — 700 p p m — 600 p p m 500 p p m Iona Jetty Iona Sewage 5 4 1 2 5 I H Treatment Plant Strait of Georgia 4-477445 5445525 _479274 Steveston Jetty 544*3039 j Vancouver International 5 ' - ff? A i r p 0 r t Canadian Coast Guard 1 hovercraft base Fraser River Middle Arm '.SI 3 • v40 658 9 48.'5307(^12 V 1 699.0 . 1 46-' \ '45 42 1691.0* / 4Y\ Fraser River Main Arm Figure 60: Areal distribution of manganese content on Sturgeon Bank 123 at stations 39 and 43. The Mn/Al distribution plot (Figure 61) reflects the Mn distribution. The relatively low Mn concentrations on Sturgeon Bank, especially in the area adjacent to the inactive sewage outfall, indicate that Mn-oxides are not abundant and therefore can not be a significant host for trace metals on Sturgeon Bank. Manganese does not correlate with grain size (r = -0.10) (Figure 62a), Mg (r = -0.03) (Figure 62b), or Fe (r = 0.00) (Figure 62c) further supporting the absence of Mn-oxides in fine-grained sediments on the bank. The high Mn/Al ratios found on the outer northern Sturgeon Bank may represent Mn-oxides, however, these stations are composed of medium sands and therefore this is unlikely. 6.3.4.6. Copper Copper tends to be concentrated in residual minerals because it is not capable of forming its own minerals and does not easily substitute for common ions in silicate rocks (Krauskopf, 1979). Copper is found in Cu sulphides such as CuO (tenorite), Cu2C03(OH)2 (malachite), Cu3(C03)2(OH)2 (azurite), CuFeS2 (chalcopyrite), CujFeS^ bornite), Cu2S (chalcocite), Ci^ O (cuprite), CuS (covellite) (Klein and Hurlbut, 1977; Nesse, 1986) and other common minerals. The highest copper content is found at station 21 (49 ppm ± 13.3%) (Figure 63) considerably lower than even the lowest values found in Howe Sound sediments (Drysdale, 1990) and values reported for marine clays, shales and sandstones (Bowen, 1979). Concentrations of Cu elsewhere on the bank are lower than 27 ppm. Sediments from uncontaminated inlets on the west coast of British Columbia range from 4 to 37 ppm (Harding and Goyette, 1989) and are similar to the values found in surface sediments on Sturgeon Bank. 124 / North Arm Jetty Grain size stations • Sea Carousel stations — 1 6 0 p p m wt.% 140 ppm/wt.% 120 ppm/wt.% 100 ppm/wt.% Fraser River North Arm Iona Jetty t N km Iona Sewage Treatment Plant -.18 in ;i9A-97 I f " > s c l 2 \ S3 83-'21 ' J * - " sV.ol1 23 1 0 5 / 19E-102 Strait of Georgia , 0 M3 '"'-22 I Vancouver International / -J 6 « "1 Airport -+ 4 7 7 4 4 5 5 4 4 5 5 2 5 , 3 ' 51 /+J79274 Steveston Jetty 54,40039 Canadian Coast Guard " c hovercraft base Fraser River Middle Arm Figure 61: Areal distribution of M n / A l on Sturgeon Bank 125 Manganese CO "c 3 Q. C CD N 'co c "S O 7 6 5 4 3 + 2 1 400 y = -0.0039X + 5.6865 R2 = 0.0904 500 600 700 800 Manganese content (ppm) 900 1000 1.8 1 16 C 1-4 8 _ 1.2 E ^ 1 .2 0.8 CO J^ , CD 0.6 + D> 0.4 4| 0.2 0 400 500 y = -0.0004x +1.4867 R2 = 0.0339 600 700 800 Manganese content (ppm) 900 1000 £ c o o c p 4.5 4 3.5 3 2.5 2 1.5 1 --0.5 0 400 • • • • y = 0.0003X + 2.9973 R2 = 0.003 500 600 700 800 Manganese content (ppm) 900 1000 Figure 62: (a) Manganese content versus grain size (b) Manganese content versus magnesium content (c) Manganese content versus iron content 126 North Arm Jetty o Grain size stations • Sea Carousel stations — 45 ppm — 40 p p m — 35 p p m — 30 p p m — 25 p p m — 20 p p m — 15 ppm 10 ppm Iona Jetty Strait of Georgia + 477445 5445525 '+479274 Steveston Jetty 5440039 ' 2 f I j Vancouver International % # ,r A i r P ° r t Canadian Coast Guard hovercraft base Fraser River Middle Arm Figure 63: Areal distribution of copper content on Sturgeon Bank 127 Copper is concentrated in the finer grain sizes with the exception of stations 3, 20 and 23 which are composed of very fine sand and lie adjacent to the once active Iona sewage outfall. The Cu/Al distribution plot reflects the Cu distribution, particularly on the northern and central Sturgeon Bank (Figure 64). The Cu/Al ratio from sediments collected from station 21 adjacent to the now inactive Iona sewage treatment plant outfall is considerably higher than the ratios from sediments of surrounding stations. The fine silt-dominated sediments found at station 40 do not exhibit the same Cu enrichment as those from station 21 which suggests the sediments found at station 21 have been contaminated by an additional source of Cu. This source was likely the Iona sewage effluent whereby Cu still remains enriched in the finer-grained surface sediments of station 21. Higher Cu concentrations at station 21 could also reflect the composition of organic matter here which, as explained previously, may be more reactive than the organic material present at station 40. It is important to note, however, that the concentration of Cu in the sediments from station 21 is low and does not show considerable contamination. Copper correlates positively with grain size (r = +0.73) (Figure 65a) reflecting surface area adsorption. Copper shows weak correlations with Fe (Figure 65b) and Pb (Figure 65c) (r = +0.33, r = +0.33, respectively) but good correlation with Zn (r = +0.78) (Figure 65d), reflecting grain size preference. As observed with vanadium, copper concentrations on Sturgeon Bank indicate that Cu distribution is texturally controlled and surface sediments are relatively uncontaminated with respect to copper. 6.3.4.7. Zinc Zinc, like copper, is enriched in residual solutions and therefore is concentrated in felsic 128 North Arm Jetty Grain size stations • Sea Carousel stations — 6.5 ppm/wt.% — 5.5 ppm/wt.% — 4.5 ppm/wt.% — 3.5 ppm/wt.% 2.5 ppm/wt.% 1.5 ppm/wt.% Iona Jetty Strait of Georgia -+477445 5445525 .479274 Steveston Jetty 54,40039 I Vancouver International A i r P ° r t Canadian ^ Coast Guard hovercraft base Fraser River : Middle Arm Figure 64: Areal distribution of C u / A l on Sturgeon Bank 129 Copper £ 0 -I 1 1 1 1 1 1 1 1 1 1 ^ 0 5 10 15 20 25 30 35 40 45 50 a Copper content (ppm) o - l 1 1 1 1 — I 1 1 1 1 1 0 5 10 15 20 25 30 35 40 45 50 b Copper content (ppm) C Copper content (ppm) o - l 1 1 1 1 1 1 1 1 1 1 0 5 10 15 20 25 30 35 40 45 50 d Copper content (ppm) Figure 65: (a) Copper content versus grain size (b) Copper content versus iron content (c) Copper content versus lead content (d) Copper content versus zinc content 130 rocks (Krauskopf, 1979). Because of its similarity in ionic size, Zn can substitute for Fe and Mg and therefore amphiboles, pyroxenes and biotite are the main zinc carriers in igneous rocks (Rankama and Sahama, 1950). Zinc concentrations in surface sediments on Sturgeon Bank range from 46 to 109 ppm ± 3.1%, are highest at stations 21 and 40 in coarse silt sediments, and decrease seaward (Figure 66). These values are significantly lower that the lowest values found in Howe Sound sediments (Drysdale, 1990) and the values reported for marine clays, shales and sandstones (Mason and Moore, 1982). The zinc vs. aluminum distribution on Sturgeon Bank shows a consistent trend with Zn distribution with the highest value found at station 21 (Figure 67). The high Zn content in sediments from station 40 is not reflected in the Zn/Al ratio. Zinc and copper distributions in Sturgeon Bank surface sediments behave similarly with the sediments collected from station 21 containing higher Zn contents likely from the once active Iona sewage treatment outfall and the higher composition of organic material here. Zinc correlates positively with grain size (Figure 68a), Fe (Figure 68b) and Pb (Figure 68c) (r = +0.91, r = +0.71, r = +0.44, respectively) and indicates the strong affinity for Zn in fine-grained sediments. Like Cu, the distribution of Zn on Sturgeon Bank reflects textural control and indicates that surface sediments are relatively uncontaminated with respect to zinc. 6.3.4.8. Lead Lead exists as the independent mineral PbS (galena), PbC03 (cerrusite) and PbS04 (anglesite) and is often co-crystallized in apatite and titanite (Bowen, 1979). Lead has an ionic size similar to Fe and Mg and therefore substitutes for these elements in silicate lattices such as 131 North Arm Jetty Grain size stations • Sea Carousel stations — 100 ppm — 90 ppm — 80 ppm — 70 ppm — 60 ppm 50 ppm Iona Jetty Strait of Georgia + 477445 5445525 Steveston Jetty 54,40039 "S5 / 6 4 - 4 , l ' 5 4 9| „«„ " \ f i Vancouver International ^ § # ^ 1 A i r p o r t Canadian - Coast Guard / • A —O + r hovercraft base Fraser River Middle Arm Figure 66: Areal distribution of zinc content on Sturgeon Bank 132 North Arm Jetty ° Grain size stations • Sea Carousel stations — 14.5 ppm/wt.% — 13.5 ppm/wt.% — 12.5 ppm/wt.% — 11.5 ppm wt.% — 10.5 ppm/wt.% — 9.5 ppm/wt.% 8.5 ppm/wt.% Iona Jetty Strait of Georgia -4- 477445 5445525 22 Vancouver I International - a ^ - - ! Airport C a n a d i a n Coast Guard hovercraft base Fraser River Middle Arm River Main Arm +479274 Steveston Jetty 5446039 Figure 67: Areal distribution of Z n / A l on Sturgeon Bank 133 Zinc OT 8 C 7 2 6 C CD N * O T C "CO O 40 y = 0.0918x-2.8354 R2 = 0.905 50 60 70 80 90 Zinc content (ppm) 100 110 5 -r 4.5 0^ 4 i 3.5 -3 c 2.5 "c 2 0 1.5 0 c 1 -Iro 0.5 • 0 --40 50 y = 0.0334X + 1.0351 R2 = 0.7077 60 70 80 Zinc content (ppm) 90 100 110 30 Q_ 25 Q. 20 c £ 15 c 8 10 T3 CO 5 CD 40 y = 0.2612x-1.774 R2 = 0.4398 50 —I— 60 —I— 70 80 —4— 90 100 110 Zinc content (ppm) Figure 68: (a) Zinc content versus grain size (b) Zinc content versus Iron content (c) Zinc content versus Lead content 134 mica and chlorite. In addition, lead was present as a gasoline additive but effective January 1, 1987, the maximum allowable lead content in leaded gasoline in Canada was reduced from 0.77 grams per litre to 0.29 grams per litre. By December 1, 1990 leaded gasoline was effectively phased out (Poon, 1989). Therefore lead has also been introduced into marine sediments through the atmosphere via automobile exhaust. Lead concentration in Sturgeon Bank sediments ranges from 4 to 28 ppm ± 58.4% with content generally decreasing seaward (Figure 69). The distribution of Pb/Al is very similar to that of Pb (Figure 70). Stations 1 and 2 show high Pb/Al values while Pb/Al values from sediments at stations 16,38 and 49 are considerably higher than those from sediments at adjacent stations. Station 54 sediments are also noticeably higher in Pb/Al value while sediments from stations 15, 47 and 48 are markedly lower than other sediments from surrounding stations. When Pb is plotted against grain size it shows positive correlation (r = +0.39) (Figure 71). Plots of Pb vs. Cu (Figure 65c) and Pb vs. Zn (Figure 68c) reveal that Pb has only a small association with copper (r = +0.33) and zinc (r = +0.44) hosted minerals. Lead values obtained using XRF analytical techniques show precision errors of more than 58% due to poor sensitivity by the XRF and low Pb concentrations. Although the values determined seem reasonable, conclusions made about lead abundance on Sturgeon Bank must be made cautiously. The low lead concentrations measured indicate that surface sediments on Sturgeon Bank are relatively uncontaminated with respect to lead. 6.3.4.9. Zirconium Zirconium is too small to substitute in most silicate lattice positions so it tends to be 135 Steveston Jetty 5 4 4 0 0 3 9 Figure 69: Areal distribution of lead content on Sturgeon Bank 136 North Arm Jetty S Grain size stations • Sea Carousel stations 4.5 ppm/wt.% 4.0 ppm/wt.% 3.5 ppm/wt.% 3.0 ppm/wt.% 2.5 ppm/wt.% 2.0 ppm/wt.% - 1.5 ppm/wt.% 1.0 ppm/wt.% Iona Jetty Iona Sewage 3 3 s \ 5 ^ _ Treatment Plant Strait of Georgia + 477445 5445525 479274 Steveston Jetty 5440039 Vancouver International A i r P ° r t Canadian Coast Guard hovercraft base Fraser River Middle Arm Figure 70: Areal distribution o f Pb /Al on Sturgeon Bank 137 s e t Grain size in phi units o -I 1 1 1 1 1 1 1 co o found in the felsic end of a rock series in residual solutions or largely found in the resistate mineral zircon (Krauskopf, 1979). Zirconium content is a good index for areas of heavy mineral accumulation. Zirconium content in shales is reported to be 160 ppm (Mason and Moore, 1982) and abundances over this value usually indicate that Zr is being hosted in the mineral zircon. In Sturgeon Bank sediments zirconium is generally highest on the inner bank and ranges in concentration from 78 to 339 ppm ± 2.4% (Figure 72), considerably higher than values found in Howe Sound sediments (Drysdale, 1990). This contrast could be the result of the coarser grain sizes found in Sturgeon Bank compared to Howe Sound. Zr/Al distribution in sediments is very similar to Zr distribution with stations 14,28, 30 and 36 showing the highest values (Figure 73). It is evident that Zr does not preferentially accumulate in certain grain size fractions and therefore Zr does not correlate well with grain size (r = +0.31) (Figure 74). The highest Zr values are found in the very fine to fine sand and coarse silt size fractions which is consistent with results of Zr distribution in coarser grain sizes found by Bowen, 1979; Krauskopf, 1979; Wright, 1972; Calvert, 1983; Drysdale, 1990. Zr-accumulation is consistent with the distribution of Cr, Ti, Fe, V and to a lesser extent Ni in surface sediments on Sturgeon Bank and is indicative of areas of heavy-mineral accumulation. 6.3.5. SEDIMENT GEOCHEMICAL VARIABILITY Station 19 was sampled 5 times in an east-west transect with a sample spacing of 2 metres. The major element concentrations measured at each of the 5 stations show only minor variation with sample 19E, the most seaward sample having the lowest Al, Ti, and Fe values. This is consistent with the increase in grain size within the station 19 transect in a seaward 139 North Arm Jetty " Grain size stations • Sea Carousel stations — 320 p p m — 280 ppm — 240 ppm — 200 ppm — 160 p p m — 120 ppm 80 p p m Iona Jetty Iona Sewage Treatment Plant Strait of Georgia -+ 477445 5445525 67.3^51 +479274 Steveston Jetty 5440039 4 Vancouver International A i r P ° r l Canadian Coast Guard hovercraft base Fraser River Middle Arm Figure 72: Areal distribution of zirconium content on Sturgeon Bank 140 * N North Arm Jetty Grain size stations • Sea Carousel stations 55.0 ppm/wt.% 50.0 ppm/wt.% 45.0 ppm/wt.% 40.0 ppm/wt.% 35.0 ppm/wt.% 30.0 ppm/wt.% 25.0 ppm/wt.% 20.0 ppm/wt.% 15.0 ppm/wt.% Iona Jetty Iona Sewage Treatment Plant Strait of Georgia -+ 477445 5445525 Vancouver International A i r P ° r t Canadian Coast Guard hovercraft base Fraser River Middle Arm +479274 Steveston Jetty 5440039 4 ... ^ Figure 73: Areal distribution of Z r / A l on Sturgeon Bank 141 direction which was previously discussed. The minor element concentrations measured at station 19 show a wider range in variation than the major elements. Cobalt content ranges from 32-82 ppm with no trend in concentration in any direction. Chromium concentrations show slight variation and are highest in a shoreward direction with the exception of sample 19E. Ni contents vary only slightly and decrease in a seaward direction, while V and Mn contents show no concentration trend in any direction. Cu content ranges from 28-34 ppm, zinc content ranges from 80-90 ppm and Pb content ranges from 18-26 ppm. All three elements show reasonably small variations between samples and no discemable trend in concentration in a seaward or shoreward direction. Zr behaves similar to Cu, Zn and Pb with only small sample variations and no Zr-concentration trends. Organic carbon behaves similar to Ni and Cr in that it decreases in a seaward direction. The low C o r g value measured in sample 19E is consistent with low Al, Ti, Fe, Ni, Zn and Pb contents measured at this station. The degree of variability and the lack of obvious trends in sediment geochemical results within a 10 metre spacing, especially in some of the minor element measurements, make it difficult to extrapolate values across the bank. Initially the 56 stations sampled for sediment geochemistry were thought to behave similarly to sediments collected from the 10 Sea Carousel sites and unfortunately geochemical analyses were not performed on the sediments collected from the Sea Carousel stations due to an inadequate sample supply. However, the degree of variability in sediment grain size results within a 10 metre spacing reveals how difficult it is to extrapolate values across the bank. Sediment geochemical results should therefore be assumed to be site specific. 143 6.3.6. GEOCHEMICAL SUMMARY OF STURGEON BANK SEDIMENTS The fine silt sediments from stations 21 and 40 show the highest concentrations of Al, Fe, Cu, and Zn. These elements are generally more abundant in the finer grain size fraction on the inner bank and decrease in content in a seaward direction. The affinity for fine-grained sediments results in good correlation of these elements with grain size. High concentrations of these elements at station 40 can be explained by textural effects due to grain size, while at station 21 high concentrations indicate an additional host is contributing. This source is likely the now-inactive Iona sewage outfall which discharged onto this area of Sturgeon Bank from 1962-1988 causing contaminant deposition. The iron present on the bank may be found in pyrite, mica, magnetite, chlorite, or ilmenite, with mica, magnetite and chlorite being the most likely phases. Sturgeon Bank surface sediments were found by Amos et al. (in prep.) to contain approximately 16% chlorite, 29% mica, 6% smectite, 39% quartz and 9% feldspar using X-ray diffraction which is consistent with the findings in this study. The Fe/Mg correlation suggests that there is an additional source of Fe than what is present as ferro-magnesian minerals, likely in the form of Fe-oxides. Fe-oxides may be responsible for the Cu and Zn enrichments at station 21. Manganese-oxides do not seem to be significant in surface sediments on Sturgeon Bank. Despite the higher concentrations of Cu, Zn and Fe in surface sediments at station 21, the values measured are relatively low and typical of uncontaminated estuaries in B.C. The enrichment of Cu and Zn in sediments collected from stations 21 and 40 is not reflected in the vanadium concentration, an element also released by sewage (Hall et al., 1974). The excellent vanadium correlation with iron indicates direct substitution of V for Fe probably in biotite, chlorite or magnetite and implies that V is not a 144 contaminant in surface sediments on Sturgeon Bank. The coarse silts and very fine to fine sands, particulary at stations 14,28, 30 and 36 tend to concentrate the heavier elements including Ti, Cr, Zr, Fe, V, and to a lesser extent Ni. This accumulation in the coarser-grained sediments results in poor correlation of these elements with grain size. Instead these elements are concentrated in areas of heavy-mineral accumulation where magnetite, zircon and ilmenite are probably more abundant. Silica and zirconium show concentrations in Sturgeon Bank surface sediments significantly higher than sediments from Howe Sound probably due to the coarse-grained nature of sediments deposited from the Fraser River. The high Co content on Sturgeon Bank can not be explained by textural effects, organic carbon content or element associations and therefore its distribution on the bank is unexplained. The organic carbon content on Sturgeon Bank is low and representative of many nearshore estuaries, while the carbonate carbon content on the bank is extremely low. The excellent correlation between C 0 I g and grain size indicates that hydraulic sorting plays a large role in the distribution of organic carbon on the bank. The association of characteristics between specific stations is demonstrated using a principal components analysis (PCA). A PCA is a data reduction technique where the primary goal is to construct linear combinations (components) of the original data variables. The successive linear combinations are constructed in such a way that they are uncorrected with each other and account for successively smaller amounts of the total data variation (Dillon and Goldstein, 1984). The elements Pb, Zn, Cu, Ni, Co, Cr and Ti02 were used as data variables in a PCA. Examination of the first three components explained 90% of the variation in the data and therefore examination of additional components was not needed. The first component weights 145 Pb, Cu, and Cr positively; Zn, Ni and Ti02 positively higher; and Co negatively. The second component weights Pb, Zn and Cu negatively, Ni slightly positively; Co and Ti02 more positively; and Cr the most positively. The third component weights Pb, Zn, and Cu positively; Co considerably more positively; and Ni, Cr, and TiOz negatively. Plotting the first two components results in a wide scatter of data points (Figure 75a). Stations 14, 28, 30 and 36 group together with stations 22 and 32 plotting close to these four stations; station 21 is plotted by itself; station 17,19A-E, 26, and 40 plot towards station 1; and stations 5, 18, 23, 27, 31 and 38 group together towards the heavy-mineral accumulators at stations 14, 28, 30, and 36. Plotting the second and third components also results in a wide scatter of data points (Figure 75b). Stations 4 and 22 (the high cobalt stations) group together with stations 5 and 18 plotting close by; station 21 is once again plotted alone; and stations 14, 28, 30, 32, 36, and 42 are closely related. Station 19 samples A-E are not grouped tightly together in either plot and confirm the that the degree of variability between samples makes it difficult to extrapolate geochemical data to other areas of the bank. 146 Principal component analysis 2 + OJ % 1 £Z CD C O 0 Q. E o cd g. 'o _ su • Stations 4,48 • 0 - 7 : • * • Stations 14, 28, 30, 36 itions 22, 32 A\ — /#\ Stations 5,18, 23, 27, ( • j • Station 40 •* StatJoQ^ V ^ ^ ^ y (^•) ^ — _ ^ ^ - « \ (• ) s t a t i o n s 17> 4 0 • Stations Station 1,2, 54 p i i ^ \ • 3,20 \ . j Stations 19a-e^ * Station 21 • -3 0 1 2 Principal component #1 4 3 3 2 2 1 1 0 a- -1 -1 -2 CO "5 c CD C o Q. E o o 15 Q. "o c Stations 19B, 19E 20 Station 21 • Station 19A S t a t i o n- s '. 2. 19C, 54 • • • Station 19D • • -+-Stations 4, 22 i \ Stations 5,18 • • + Station 48 Stations 9,42 Station 30 • Stations 14, 32, 42 Stations 28, 36 . Station 45 -3 - 2 - 1 0 1 Principal component #2 Figure 75: Principal componenet analysis using Pb, Zn, Cu, Ni, Co, Cr, Ti02 147 Chapter 7: SUMMARY AND CONCLUSIONS 7.1. SUMMARY The fine-grained cohesive sediments from the inner bank require applied current velocities for sediment suspension greater than either wave particle or tidal velocities are known to reach on the bank. Therefore, sediments at these stations are not easily eroded. If the critical shear velocity for erosion is reached at stations 1, 2 and 14, sediments should erode very easily due to the presence of weak layers below the surface. It is for this reason that the entire failure envelope of a sediment rather than just its surface strength must be examined. Stations 3 and 13 do not show this weak layer below the surface and as a result erosion rates considerably lower than the other inner bank stations. It is expected that velocities capable of suspending sediments on the inner bank may be reached on the initial incoming or final outgoing tide especially in the presence of waves and therefore play a significant role in sediment transport. However these velocities could not be measured. The decrease in current velocities in a shoreward direction suggests that waves do not break but dissipate energy as they move across the bank as first suggested by Medley (1978). High suspended sediment concentrations on the inner bank imply that sediments are being supplied from the outer bank diffusively resulting in overall sediment accumulation on the inner bank. This diffusive nature is responsible for the increase in SSC in a shoreward direction. Non-cohesive sediments on Sturgeon Bank are suspended more easily because of their lack of cohesive strength, especially the fine-grained sands on the outer southern Sturgeon Bank. At all stations composed of non-cohesive sediments wave particle velocities (high-frequency 148 velocity fluctuations) capable of suspending sediments were reached. At station 11, where suspending velocities were reached several times, even tidal current velocities seemed capable of sediment erosion. A considerable amount of sediment is transported in a flooding direction from the outer southern bank implying advective movement of sediment in a shoreward direction. Sediment transported shoreward from the outer southern bank suggests erosion in this area and no evidence of sediment replenishment from the Fraser River is observed. The GPS-generated perspective of Sturgeon Bank (See Figure 3) shows lower elevations on the southern relative to the northern portion of Sturgeon Bank supporting this observation. The grain size, sorting, and geochemical data also support the transport of sediment shoreward with coarser-grained, better sorted, heavy-mineral-rich sediments occurring on the inner southern bank at stations 28, 30, 32, and 36. Sediment transport rates in both flooding and ebbing directions on the outer southern bank are up to 8 times higher than on central Sturgeon Bank. On the outer central bank sediment transport in an ebbing direction is higher, however transport rates are low in both directions and therefore not considered significant. Sediment appears to be supplied from the Main Arm and to a lesser extent Middle Arm of the Fraser River on the outer central bank and elevations are high relative to the outer southern bank. Current velocities generated from fluvial discharge from the Middle Arm appear to play a minor role in sediment transport on the outer central bank. Despite the strong influence from the Middle Arm flow at station 14, discharge velocities capable of eroding sediments here are not reached even in freshet flows. Recently GeoSea Consulting completed a report discussing sediment transport and its environmental implications in the lower Fraser River and Fraser delta (McLaren and Ren, 1995). 149 In this report the authors concluded that most of the intertidal flats are not receiving sand through normal deltaic processes and that there appears to be insufficient sand passing through the Middle Arm to have any impact on Sturgeon Bank. The report also suggests that intertidal sediments between the jetties no longer have any relationship with the Fraser River sediments. These findings are somewhat consistent with this study in that sediments are being eroded from the outer southern area of the bank and transported shoreward and these sediments are not being replenished from the Fraser River discharge. In contrast to the GeoSea report, this study concludes that sediments supplied from the Middle Arm, although minor, reach the outer central bank area and that sedimentation on the inner bank is taking place through not only advective but also diffusive processes which bring Fraser River sediment to the inner bank. The generally high erosion thresholds, low erosion rates and low current velocities measured on the bank imply that a considerable amount of the sediment in suspension on the bank is derived from the Fraser River with a smaller amount derived from erosion of the bank itself. However waves can strongly influence the concentration of suspended sediments on Sturgeon Bank especially on the outer southern bank where sediments are more easily eroded as stated above. Winds from the west are most likely to increase current velocities, sediment erosion, suspended sediment concentration and sediment transport. Bioturbation by benthic organisms found on the bank will also contribute to increased sediment resuspension. In contrast, benthic diatoms may act as biostabilizers on the sediment surface especially on the inner bank, therefore decreasing the likelihood of sediment resuspension. Geochemical analyses of surface sediments on Sturgeon Bank show little sign of contamination from anthropogenic Cu, Zn, Fe, V, Cr, Ti or Pb. The distribution of these 150 elements is more likely controlled by textural differences in grain size within the sediment. For this reason, the elemental composition of sediment samples should not be compared unless grain size effects are taken into consideration. Sturgeon Bank may contain lower concentrations of some anthropogenic tracers due to the general coarse-grained nature and relatively low clay contents of surface sediments. Fe, V, Ti, Cr, and Zr are concentrated in areas of heavy mineral accumulation on the inner southern Sturgeon Bank and adjacent to the North Arm channel at station 14. The distribution of these elements is controlled not only by sediment texture but by the physical controls on sediment transport. Cobalt behaves unlike any other minor element analyzed in this study. Co content is significantly higher than average values measured in igneous rocks and sediments from uncontaminated estuaries. Both the source and the host of the cobalt in Sturgeon Bank surface sediments is unknown and should be investigated. Organic carbon content may contribute to the distribution of minor elements on the bank with potentially more reactive organic carbon found adjacent to the once active Iona sewage outfall. Organic carbon contents in Sturgeon Bank surface sediments however are low and thus only explain some of the minor element distribution. The higher Cu/Al, Pb/Al and Zn/Al ratios found at station 21 compared to station 40 in fine-silt sediments suggest that the distribution of these elements adjacent to the inactive outfall is due to controls in addition to grain size. Fe-oxides may be hosting some of the minor elements but Mn-oxides do not appear to be significant on the bank and therefore are unlikely hosts for metal accumulation. 151 7 . 2 . C O N C L U S I O N S Time, manpower and equipment limits the amount of data feasibly collected in any project. This study attempted to link together a multitude of aspects so that a more comprehensive view of the processes which control sediment and contaminant distribution on Sturgeon Bank could be understood. It was concluded from this study that 1) contamination on Sturgeon Bank from the sewage discharged there from 1962-1988 appears to have been greatly reduced in the surface sediments; 2) cobalt contents on the bank are high and need to be investigated; 3) minor element distribution appears to be controlled by both grain size and the physical processes responsible for sediment transport; 4) sediments from the outer southern bank appear to be easily eroded and transported shoreward, especially when waves are present, with no discernable sediment replenishment from the Fraser River; 5) currents measured on the inner bank are not capable of eroding sediments. However eroding velocities are expected to occur on the initial and final stages of the tide resulting in a high concentration of sediment suspended due to weak subsurface layers in sediments on the inner bank; 6) both advective and diffusive processes are responsible for supplying the inner bank with sediment; 7) the degree of variability in erosion thresholds, current velocities and directions, suspended sediment concentrations, grain size and sediment geochemistry restricts the extrapolation of specific results to other areas of the bank. The present results should therefore be considered both spatially and temporally specific. 7.2.1. RECOMMENDATIONS Analyses of sediment cores would improve the understanding of surface sediments on Sturgeon Bank by providing a means to obtain sediment accumulation rates. A knowledge of the 152 subsurface geochemistry may also explain the resulting surface geochemistry. A detailed study to examine the variation in suspended sediment concentration over a tidal cycle and in the presence of waves as well as a more precise method of collecting a depth-integrated water sample would improve the understanding of suspended sediment dynamics. A more intensive look at erosion thresholds over more areas of the bank including within the Middle Arm channel and across the middle of the bank would greatly increase the knowledge of Sturgeon Bank sediment stability. Velocity fluctuation measurements in shallow-water conditions would provide information on currents generated on an initial rising and final falling tide. If sediments on the bank are being transported shoreward, a detailed look at the geochemistry and transport of sediments within the marsh may reveal the sink for contaminated sediments on the bank. These investigations would provide information needed to refine the conclusions of this study. 153 REFERENCES Abbey, S., 1980. 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This approach is suited for surveying intertidal areas which are difficult to access and are not represented on bathymetric and topographic maps in detail. Differential GPS involves the use of two receivers collecting data simultaneously; one receiver over a known reference point and one receiver on an unknown point (static) or on a moving platform (kinematic). The GPS solution is affected by error in the satellite orbits, satellite clocks, receiver clocks, and deliberate signal degradation by the U.S. Department of Defense (Selective Availability, or SA) (Wells et al., 1987). When the reference receiver is over a known reference point the receiver determines the error in signals and in post-processing these corrections are applied to the second receiver, provided the second receiver is within a given range (in this application < 50 km). Differential kinematic GPS allows position determination at the centimetre level (post-processed) with accuracies of 0.5 cm ± 1 to 2 ppm of the baseline (Remondi, 1985). A full overview of the Global Positioning System is available in Leick (1990) or Wells et al. (1987). Morton and Leach (1993) provide an introduction for a kinematic GPS survey on beach sediments. 163 Two geodetic quality GPS receivers and two GPS antennas (one specifically for mobile data collection) were used. Prior to mobile data collection an accessible reference point was established at the Canadian Coast Guard hovercraft base, Vancouver International Airport. The reference point co-ordinates were determined via a static differential survey tied to a first-order survey marker in Steveston, approximately 9 km away. The reference position is accurate relative to the Steveston marker at the sub-centimetre level and has the co-ordinates 49°10'51.8371, 123°11'4.9314 and a height of 3.406 m. The accuracy of all mobile GPS solutions are relative to the established reference co-ordinates. In order to solve for the unknown variables (latitude, longitude and height) with the GPS solution in post processing, both GPS receivers must maintain continuous phase lock with at least four common satellites throughout the survey. The GPS survey was conducted at spring low tides on July 29 and 30, 1993, to obtain ground elevations of the bank. The GPS solution provides a position for the antenna. To obtain the ground position, the height of the antenna mounted on the hovercraft was measured before and after the survey and this height subtracted from the position data. Height was fixed by keeping the hovercraft at full inflation during height measurement and while collecting transect positions. The hovercraft traversed twelve transects between the Iona and Steveston jetties, spaced approximately 500 m apart while the mobile receiver recorded position data once every second. Speed of the hovercraft averaged 25 knots and each transect took an average of 10 minutes, providing close to 600 data points for each of the twelve transects. The antenna height variations before and after the survey were -4.9 cm and +6.4 cm for July 29 and July 30, repsectively. 164 Kinematic data were processed with the U.S. National Geodetic Survey OMNI processing software. The solution files contain the starting index position for the mobile antenna and an independent position solution for each second of data collection. The position solutions are expressed as delta values from the starting position. All positions were then transformed to latitude, longitude and height (WGS 84) using the known reference station co-ordinates. Data points at the end of each transect were removed because the hovercraft loses height when it slows to make a turn. Each position data point was plotted in ARC/Info, a commercial GIS program, and a contour map created. The contours were then overlayed on the station location map of Sturgeon Bank where the elevations of each station could be observed directly from the map (Figure 76). The contours were then used to develop a three-dimensional perspective of the Sturgeon Bank area using ARC/Info (Figure 77). While collecting the position data, the locations of "wetted" areas of the bank were also being recorded by visual examination and verbal indication. These positions were then plotted on the traverse map and the approximate location of channels on the bank were drawn in and the channel locations overlayed on the perspectives map (Figure 78). This was subject to some human interpretation due to the fact that wetted areas on the bank may not be the result of tidal channels but simply the product of areas which remain wet (with as little as lor 2 cm of water over them) even when the bank is completely exposed. It should therefore be interpreted as the "wetted" areas in some places rather than the position of channels. 165 North Arm Jetty Height in metres relative to mean sea level I 0.3 to 0.6 0.0 to 0.3 I -0.3 to 0.0 J -0.6 to -0.3 I -0.9 to -0.6 I -1.2 to -0.9 I -1.5 to -1.2 I -1.8 to-1.5 I -2.1 to-1.8 I -2.4 to -2.1 Fraser River North Arm Iona Jetty Grain size stations Sea Carousel stations -1-477445 5445525 Steveston Jetty * N km Iona Sewaae Treatment Plant Strait of Georgia Vancouver International ^POrt Canadian Coast Guard hovercraft base Fraser River Middle Arm Figure 76: Sturgeon Bank contours constructed from GPS kinematic survey data 166 167 Figure 78: Approximate channel locations constructed using GPS kinemeatic survey 168 Appendix II: GEOGRAPHICAL STATION LOCATIONS ON STURGEON BANK Station Latitude Longitude Easting Northing l 49 14.12 123 15.25 481497 5453429 2 49 13.42 123 14.83 482002 5452130 3 49 13.02 123 13.87 483165 5451386 4 49 13.58 123 14.01 482998 5452424 5 49 13.04 123 12.89 496201 5451398 6 49 12.81 123 15.32 481404 5451002 7 49 13.26 123 15.59 481079 5451837 8 49 11.61 123 16.19 480340 5448783 9 49 11.71 123 15.03 481749 5448963 10 49 12.40 123 14.85 481972 5450241 11 49 12.21 123 14.28 482663 5449886 12 49 12.36 123 14.21 482748 5450164 13 49 11.79 123 14.03 482964 5449107 14 49 11.63 123 14.41 482501 5448812 15 49 11.37 123 13.86 483168 5448328 16 49 11.36 123 13.60 483483 5448309 17 49 11.36 123 13.21 483957 5448308 18 49 12.54 123 13.86 483174 5450496 19 49 12.49 123 13.35 483793 5450402 20 49 12.79 123 12.94 484293 5450956 21 49 12.42 123 12.83 484424 5450270 22 49 11.82 123 13.27 483887 5449160 23 49 12.26 123 13.74 483318 5449977 24 49 10.31 123 14.73 482105 5446368 25 49 10.37 123 14.22 482725 5446477 26 49 10.58 123 13.27 483880 5446863 27 49 10.15 123 12.92 484303 5446065 28 49 10.03 123 13.80 483233 5445846 29 49 9.86 123 14.23 482710 5445532 30 49 9.88 123 13.38 483743 5445566 31 49 9.70 123 12.93 484288 5445231 32 49 9.40 123 13.31 483825 5444676 33 49 9.27 123 13.69 483362 5444437 34 49 9.31 123 14.70 482135 5444515 35 49 8.91 123 14.02 482959 5443771 36 49 9.16 123 12.88 484346 5444230 38 49 8.76 123 12.88 484344 5443489 39 49 8.63 123 13.23 483918 5443250 40 49 8.20 123 12.92 484293 5442452 41 49 7.96 123 13.09 484085 5442008 42 49 8.14 123 13.45 483648 5442342 43 49 8.28 123 13.35 483770 5442601 44 49 8.26 123 14.05 482919 5442567 45 49 8.06 123 14.06 482906 5442196 46 49 8.05 123 14.40 482492 5442179 47 49 8.32 123 14.44 482445 5442680 48 49 8.43 123 14.64 482203 5442884 49 49 8.92 123 15.67 480954 5443796 50 49 7.78 123 15.63 480995 5441684 51 49 7.43 123 16.22 480276 5441038 52 49 7.76 123 16.58 479840 5441651 53 49 14.23 123 16.12 480442 5453637 54 49 11.93 123 16.46 480014 5449377 55 49 10.05 123 16.56 479880 5445894 56 49 8.40 123 16.05 480489 5442834 57 49 12.47 123 16.45 480030 5450377 169 Appendix II cont'd: Station Latitude Longitude Easting Northing SI 49 12.78 123 12.35 485009 5450936 S2 49 12.62 123 12.73 484547 5450641 S3 49 12.47 123 13.34 483805 5450365 S4 49 12.25 123 14.48 482420 5449961 S4a 49 12.51 123 14.74 482106 5450444 S5 49 11.84 123 15.44 481252 5449206 S6 49 11.75 123 16.26 480256 5449042 Sll 49 08.39 123 15.54 481109 5442814 S12 49 08.47 123 14.09 482872 5442956 S13 49 08.29 123 12.73 484524 5442618 S14 49 10.38 113 13.11 484073 5446492 170 Appendix III: TIME SERIES PLOTS FOR SEA CAROUSEL ERODIBILITY DATA 171 Sea Carousel Results Station 1 17.0 17.1 17.2 17.3 17.4 17.5 17.6 17.7 17.8 17.9 18.0 Time (PDT) 6000 OBS upper OBS ambient OBS lower "'"'"'""I1 1 ""f" 1 11111 1 '"""IIIII iimiii nnnnrnnimirm 17.0 17.1 17.2 17.3 17.4 17.5 17.6 17.7 17.8 17.9 18.0 Time (PDT) LU -o 17.0 17.1 17.2 17.3 17.4 17.5 17.6 17.7 17.8 17.9 18.0 Time (PDT) Figure 79: Time series plots of Sea Carousel Results at station 1 (a) Current speed versus time (b) Suspended sediment concentration versus time (c) Ersosion rate versus time 172 Sea Carousel Results Station 2 CO E T3 CD CD CL CO C CD i_ i_ o 1.3 --1.1 --0.9 --0.7 --0.5 --0.3 -0.1 -0.1 12.3 - Azimuthal current -Vertical azimuthal 12.5 12.7 12.9 13.1 Time (PDT) 13.3 13.5 13.7 C CD E X3 CD CO 6000 5000 4000 "§ g> 3000 { S 2 0 0 0 \ CL CO Q . cn - OBS upper - OBS ambient -OBS lower 12.9 13.1 Time (PDT) 13.7 0.003 12.3 TYPE I TYPE II 12.5 12.7 12.9 13.1 Time (PDT) 13.3 13.5 13.7 Figure 80: Time series plots of Sea Carousel Results at station 2 (a) Current speed versus time (b) Suspended sediment concentration versus time (c) Ersosion rate versus time 173 Sea Carousel Results Station 3 1.3 --E 1.1 ---a 0.9 --CD pe 0.7 --CO 0.5 --c CD 0.3 -L— 0.1 ? O DI -0.1 " -Azimuthal current - Vertical azimuthal 13.7 13.9 14.1 14.3 14.5 Time (PDT) 14.7 14.9 •£ 1400 CD £ 1200 T3 CD CO T3 CD TJ C CD Q. CO Q. CD 1000 800 600 400 200 13.7 13.9 14.1 14.3 14.5 Time (PDT) OBS upper OBS ambient OBS lower 14.7 14.9 13.7 13.9 14.1 14.3 Time (PDT) 14.5 14.7 14.9 Figure 81: Time series plots of Sea Carousel Results at station 3 (a) Current speed versus time (b) Suspended sediment concentration versus time (c) Ersosion rate versus time 174 Sea Carousel Results Station 13 TJ CD CD Q . CO C CD I— Z3 o 20.1 •£ 600 CD E 500 TJ CD CO 400 + TJ CD TJ C CD Q . CO Q . Z3 CO >^ 300 200 100 20.1 CM E CJ) CD CO DC c g CO o LU ^liillfliniihiiTiLlJffpTatgTtmiTnT 20.2 20.3 20.4 20.5 20.6 20.7 20.8 Time (PDT) -OBS upper -OBS ambient -OBS lower 20.2 20.3 20.4 20.5 20.6 20.7 20.8 Time (PDT) 20.6 20.7 20.8 Time (PDT) Figure 82: Time series plots of Sea Carousel Results at station 13 (a) Current speed versus time (b) Suspended sediment concentration versus time (c) Ersosion rate versus time 175 Sea Carousel Results Station 14 19.5 19.7 19.9 20.1 20.3 20.5 20.7 Time (PDT) 19.5 19.7 19.9 20.1 20.3 20.5 20.7 Time (PDT) 19.5 19.7 19.9 20.1 20.3 20.5 20.7 Time (PDT) Figure 83: Time series plots of Sea Carousel Results at station 14 (a) Current speed versus time (b) Suspended sediment concentration versus time (c) Ersosion rate versus time 176 Sea Carousel Results Station 4 1.3 + 1.1 JM «§, 0.9 TJ <D CD Q. CO •4—* c 2> o 0.7 + 0.5 0.3 0.1 -0.1 -h=t -Azimuthal current - Vertical azimuthal m o m o i o o i o o m o m o i n o i o o i o o m o t n o i o o C D O l O J O O r - T - W N t O n ' t ^ i n i o t o l D S S l D l f l O l t J l O i r i u )u ) (d<d (d6 (D<o ' vo (d (d (d (d<d (D (od (d (d<d (DS o m O T— T— Time (PDT) 5000 £^ 4500 CJ) £ 4000 C 3500 CD E 3000 TJ $ 2500 "S 2000 TJ § 1500 Q. ^ 1000 CO 500 - OBS upper - OBS ambient -OBS lower m o in o co cn cn o i n o i o o i o o i n o i n o w o w o i o o w o w o m o i o o ^ T ^ N w q n ^ ^ i n i n t p t p s N c q q o j o i o O T - r Time (PDT) Figure 84: Time series plots of Sea Carousel Results at station 4 (a) Current speed versus time (b) Suspended sediment concentration versus time 177 Sea Carousel Results Station 5 o oo o CJ Time (PDT) 1750 --1550 --CJ) E 1350 --c CD 1150 --E XJ 950 --CD W TJ 750 -CD TJ C 550 1 3 CD Q . CO Q . 350 --3 CO 150 ---50 + o in o r«- f~ oo o o o CM CM Cvl Time (PDT) Figure 85: Time series plots of Sea Carousel Results at station 5 (a) Current speed versus time (b) Suspended sediment concentration versus time 178 Sea Carousel Results Station 6 to E T3 CD CD Q . (0 C CD i_ o D) E, +—* c 0 E T J Q) to T J tl) T J C (1) CL (0 CL 13 CO 1.1 0.9 0.7 + 0.5 4-0.3 4-0.1 -0.1 - Azimuthal current - Vertical azimuthal m o m o i o o i o o m o m o m o m o m o i o c o c o o o c o c o G O c o c o c o c o c o o > o > 0 ) 0 ) 0 > 0 ) c n o m o in o> o> tn oi oi oi IO o m to Time (PDT) 4900 4400 3900 --3400 --2900 --2400 1900 1400 + 900 -OBS upper - OBS ambient - OBS lower i n o m o m o i n o m o m o m o i n o m o m o i n o m o o 3 c o c o c o o o c o o o o o c 6 c d c d c r i o S o S o S o S o > a > a > c T > o S o S o S o S Time (PDT) Figure 86: Time series plots of Sea Carousel Results at station 6 (a) Current speed versus time (b) Suspended sediment concentration versus time 179 Sea Carousel Results Station 11 1500 O L O o m o m o i o o m o i o o i o o m o m o o j o i o j o i o o o o o o o o o o o o o o o Time (PDT) Figure 87: Time series plots of Sea Carousel Results at station 11 (a) Current speed versus time (b) Suspended sediment concentration versus time 180 Sea Carousel Results Station 12 0.6 3 o 0.1 -0.1 o 03 1500 1300 + -100 Azimuthal current Vertical azimuthal IO oo o CO r^  in Oi o o in o o CM in CM o CO in CO o Time (PDT) OBS upper OBS ambient OBS lower P miiiiiirrm q B i m m r Mi|iimiiiiiii|||||||||||||||inTTmTTt™11 ''n| 1 o co in co o o in CT) o co oo o CO Time (PDT) Figure 88: Time series plots of Sea Carousel Results at station 12 (a) Current speed versus time (b) Suspended sediment concentration versus time 181 Appendix IV: PHYSICAL OCEANOGRAPHIC DATA ON STURGEON BANK rV-1. Station SI The current meter deployed at station S1 was only inundated for 18% of the time usually for 3 to 4 hours per submersion interval. One-minute-averaged velocities for the time of inundation range from 2.19 to 13.18 cm/s with a mean value of 5.68 cm/s (Figure 89). The tidal curve for the month of June, 1993 was superimposed on the measured current values to determine trends in velocity measurements over the spring and neap tides. The two peaks in velocity measured at station 1 coincide approximately with the time of the highest (spring) tidal ranges. Values are highest through sampling periods June 9 (2100-2400 h) and June 21 (1900-2200), with velocities of 12.91 and 13.18 cm/s, respectively. Wave particle velocities reach 38 cm/s on June 21 between 1900 and 2200 hours in directions ranging from 260° to 290°, approximately an ebbing direction (Figure 90). Currents at station S1 only exceed 30 cm/s 10 times for the entire length of the survey with most of these values occurring on the June 21 inundation mentioned above. Currents over 30 cm/s occur more often in a flooding direction, however the high currents found on June 21 are in an ebbing direction. Current velocities never reach 73 cm/s, the critical shear velocity for erosion, at any time during the sampling period. Plots of average speeds and directions over 10° increments show no preferred orientation (Figure 91). This averaging effectively filters out wave effects similar to the one minute averaging described above. Average velocities range from approximately 4.2 to 7.8 cm/s. Although the frequency of occurrence of currents in any direction shows no trend, the velocity 182 Tidal height (m) CD C ~3 i_ O CD D ) C cd 15 "-«—• c 0 •0 CD CO O CL E CD C GL O 13 CO £ 'CD CO c • CO CD dar CO T 3 CO E 0 M— CO TD CD CD Q. CO *-» C CD i_ O 00:0 E6A/Z 00:0 £6/62/9 00:0 E6/ZZ/9 00:0 E6/QZ/9 00:0 E6/E2/9 00:0 E6/L2/9 t 00:0E6/6L/9 00:0 E6/ZI/9 CD E i-00:0 E6/S1/9 00:0 E6/EI/9 00:0 E6/U/9 00:0 E6/6/9 00:0 E6/Z/9 00:0 E6/9/9 00:0 E6/E/9 00:0 E6/1/9 (S/LUO) paads juajjno 183 t>81 Current speed (cm/s) 31 TO' c o < o, <: o C/5 c M3 O 0 1 to to o o cr • D OQ 3' ?? <—• 5 g Q O o 3 Station 1, June 3 - June 30, 1993 current speed averaged over 10° intervals and frequency of flow directions over 10° intervals 8 T i + 0 -I—i—i— i—i— i—i—i—i—i—i—i— i— i—i—i— i— i— i— i— i— i—i—i— i—i—i—i— i— I—i— i—i—i— i—i t o i n i n u o i o i f l LO t q u o u o i o m i f l u ) i n u ) I O i n i q i o i o i o i o i o m c o m m t o i o c o m m t o t o u ? •— CN CO <cj m O r«- CO O O ! - C N r O r j l f ) > O N t D f > O r - t N f O « I i n O N i D O ' O • — CN f O ^ T l O -— •— •— — - — • — • — - — < — - — C N C N C N C N C N C N C N C N C N C N ( O O tO cO CO t O C N C N C N C N CN CN CN CN CN CN m cO cO rO <0 r O Direction (°) Figure 91: Average speed and direction plotted over 10 degree-averaged increments at station 1 185 does peak slightly in ebbing and flooding directions (approximately 250-260° and 70-80°, respectively) with the flood currents averaging slightly higher than the ebbs. The population of the data used in the generation is given in the legend of the 10° averaged increment plots. Data collected from current meters situated on the inner tidal flat will have a smaller population because of the shorter period of inundation. The maximum percentage in one 10° class interval is also given in the legend and the mean percentage is based on the percentage values in each petal or cell. This value should not be viewed as a dominant direction as currents at most stations are bidirectional in nature. Standard statistics of deviation and trend were calculated using methods of Davis (1986). A confidence interval of 95% was used throughout the calculations. Water temperatures at the beginning of June are approximately 19°C and drop to 15°C on June 9 (Figure 92). Temperatures begin increasing until June 17 where they reach 26°C and then decrease to 19°C again by the end of the month. Temperatures within an inundation interval vary up to 3°C but typically only 1.5 to 2°C. Both temperatures and salinities are measured 4 times during a one minute current meter sampling interval however the variation within the minute is not significant at station SI. Salinity measurements at station SI shows two peaks through the month of June (Figure 93). Measurements at the beginning of June are approximately 6%o and then increase to 12.5%o on June 8 and 9 before dropping to 2%o on June 29. The variation in salinity and temperature measurements over the 4 week sampling period shows a good relationship with the tidal cycle and therefore is assumed to be partially the result of spring and neap tidal effects. Salinity can vary from 4.5%o to 12%o over a sampling inundation period. Typically salinity varies 0.5 to 2%o over an inundation interval. 186 fJLM I I I I *K MM to CJ CJ CO CJ i -CJ CJ o CM (srnsieo seaiBep) ejniBjedwei 187 00:0 f 6/2/Z 100:0 V6/1/L 00-0 V6/0E/9 00-0 P6/62/9 00:0 fr6/82/9 1 00:0 t-6/Z2/9 00:0 W/92/9 100:0 W/92/9 00:0 V6/fr 2/9 00:0 fr6/E2/9 00:0 fr6/22/9 00:0 Wt2/9 00:0 f 6/02/9 t 00:0^ 6/61/9 00:0 f 6/81/9 00:0 fr6/Z 1/9 00:0*6/9179 00:0 t-6/91/9 100:0 fr6/n/9 00:0^ 6/91/9 00:0fr6/2t/9 00:0fr6/U/9 1 00:0fr6/0L/9 00:0 V6/6/9 00:0 W/B/9 00:0 f6/Z/9 00:0 fr6/9/9 00:0 W/S/9 00:0 W/W9 t 00:0 w/e/9 00:0 fr6/2/9 -m-3 ^ H H 1 • B jj . 00:0 f 6/2/Z 00:0 fr6A/Z 00:0 f6/0E/9 00:0 *6/62/9 00:0 WBZ/9 t 00:0 f 6/Z2/9 00:0 fr6/92/9 t 00:0 W/S2/9 00:0 fr6V*2/9 00:0 fr6/e2/9 00:0 00-0 WlZ/9 00-0 W/02/9 00:0^6/61/9 t 00:0fr6/81./9 00:0 f6/Z 1/9 + 00:0 fr6/91/9 00:0 W/91/9 00:0fr6/U/9 00*30 *6/BM9 00:0 V6/31/9 00:0^6/11/9 00:0 fr6/01/9 00:0 P6/6/9 00-0 f 6/8/9 00:0 P6/L/9 00:0 fr6/9/9 00:0 W/S/9 00:0 fr6/W9 + 00:0 fr6/G/9 00:0 fr6/2/9 (jdd) Auups 188 IV-2. Station S2 The current meter deployed at station S2 was submersed for 44% of the total sampling time for 3 to 15 hours per sampling interval. One-minute-averaged velocities range from 3.01 to 13.82 cm/s with a mean value of 6.39 cm/s (Figure 94). Values are highest through the sampling interval May 11 (2000 h) to May 12 (0200 h). Superimposing the tidal range curve over the measured velocities shows little association and suggests that velocity measurements at station S2 for the month of May, 1993 are unrelated to spring and neap tidal currents. Wave particle velocities at station S2 exceed 30 cm/s only 7 times, less than station 1, and all in the sampling interval on May 11 mentioned above (Figure 95). Currents in a flooding direction (-50-110°) of this interval reach 37 cm/s, the only velocity over 30 cm/s, while the ebbing direction (-260-320°) shows values over 30 cm/s 6 times, with a peak obtaining 43 cm/s. In general, flood tide current velocities exceed ebb tide current velocities, however the high currents found on May 11 occur in an ebbing direction. Currents at station S2 never reach the critical shear velocity for erosion of 86 cm/s at any time during the sampling period. Current plots averaged over 10° increments show no strongly preferred orientation (Figure 96). Average velocities range from 4.8 to 8.3 cm/s with several peaks in random directions. The highest peak lies between 30 and 50° however an additional peak exists between 120 and 130° and three peaks lie between 210 and 320°. Although two distinct peaks in velocity due to flooding and ebbing currents are not evident, currents in the general flooding direction are slightly higher than those in the ebbing direction. Water temperatures at the beginning of May are -11°C and climb to 25°C on May 16 189 06T Current speed (cm/s) CJQ C <2 O 3 CD CD o O 3 VO U J ft O 3 5/1/93 0:00 5/3/93 0:00 5/5/93 0:00 5/7/93 0:00 5/9/93 0:00 + 5/11/93 0:00 3 ' C ' i-f CD i CD "I P era CD p. < O _ | ~ ® 5/13/93 0:00 5/15/93 0:00 5/17/93 0:00 + 5/19/93 0:00 5/21/93 0:00 5/23/93 0:00 + 5/25/93 0:00 5/27/93 0:00 5/29/93 0:00 5/31/93 0:00 6/2/93 0:00 6/4/93 0:00 H o (ui) iu&eu. |Bpii Station 2, May 7 - June 3, 1993 current speed averaged over 10° intervals and frequency of flow directions over 10° intervals CO E o, T J CD 0 a CO ^T* j^Tr •sj'si^r^jf n i i 'i "j ' i t'^r v ^j^r^r^r^r^j »j ^ rj rj ^ t j C N C O ^ l O - O r v O O O O •— CN CO ' J l f i ' O N O O ' O r - C N l O T j m O N C O O o <— CN C O ^ - l O •— ^ r - r - r - ^ i - 1 - . - i - C M C M N W C N C M W N O I C N fO fO W cO cO CO 10.0-8.0-o c 0 CT 0 6.0-J, 4.0H Calculation Method Frequency Class Interval 10 Degrees Population 11800 Maximum Percentage.4.9 Percent Mean Percentage 2.8 Percent Standard Deviation 0.80 Percent vector Mean 214.18 Confidence Interval 6.72 Degrees R-mag 0.11 2.0-O O O O O o o o o o o o o o o o o o o o o o o o o o o o o o o •O f-. CO O O r - ^ ( 0 ^ l f l < ) N C O f > O ^ O J ( r ) ' J l O > O N C O r > O '— CN CO ^ LO -o •— C M C N C M C N CN CN CN Ol CN CN CO CO CO CO CO CO CO Direction (°) Figure 96: Average speed and direction plotted over 10 degree-averaged increments at station 2 192 (Figure 97). Temperatures decrease to 14°C by May 22 before increasing to 21°C on May 27 where they remain stable until May 31 and then begin a slow decline to 16°C by the end of the survey. This trend follows the tidal curve where warmer waters seem to be associated with the neap tidal time and cooler temperatures coincide with the spring tides. This observation is not unexpected as neap tides are considerably shallower than the spring tidal heights and therefore carry warmer surface water with them. The Fraser River discharge also peaks on May 16 and may bring warmer fresh water to the bank. Temperatures within a sampling inundation vary by as much a 7°C over the 15 hour current meter submersion. Generally temperatures decrease over the submersion period as expected because deeper water moves over the sampling instrument. Temperatures often remain low until the end of the inundation, however, in some cases they increase as the water shallows again. The salinity measured at station S2 is 24%o at the beginning of May and decreases to 2%o by May 18 (Figure 98). Salinity increases slowly until May 26 to 13%o and then decreases to 7%o for the remainder of the sampling period. This trend is similar but in reverse to that described by the temperature measurements at this station. The spring tides effectively bring more saline (deeper) water to the bank and the neap tides carry the fresher surface water. The effect of the Fraser River discharge may enhance this effect by bringing more fresh water to the bank at the peak of the freshet. Salinity varies over a sampling inundation by as much as 10%o but typically 2 to 6%o. Salinity values are generally low at the start of an inundation and increase rapidly as the more saline deeper water encroaches. Salinity often stays high as the tide ebbs suggesting that the water becomes more mixed as it moves up the bank but in many cases it decreases again as the water shallows. 193 P61 Temperature (degrees Celcius) c SO rt •-! 1 re I N 5 ' 3 09 3" 1-1 CD o a cr o fa VO o to 5/7/94 0:00 5/8/94 0:00 5/9/94 0:00 5/10/94 0:00 5/11/94 0:00 5/12/94 0:00 5/13/94 0:00 5/14/94 0:00 5/15/94 0:00 5/16/94 0:00 5/17/94 0:00 5/18/94 0:00 5/19/94 0:00 O 5/20/94 0:00 5/21/94 0:00 3 5/22/94 0:00 CD 5/23/94 0:00 5/24/94 0:00 5/25/94 0:00 [ 5/26/94 0:00 5/27/94 0:00 5/28/94 0:00 5/29/94 0:00 5/30/94 0:00 5/31/94 0:00 6/1/94 0:00 6/2/94 0:00 6/3/94 0:00 6/4/94 0:00 £61 Salinity (ppt) 5/7/94 0:00 s OO CO £L < 9. CO <—f 5" 3 5" >i Er ro O a o v£5 VO UJ & s> o' 3 t o 5/8/94 0:00 | 5/9/94 0:00 5/10/94 0:00 5/11/94 0:00 5/12/94 0:00 f 5/13/94 0:00 5/14/94 0:00 | 5/15/94 0:00 5/16/94 0:00 5/17/94 0:00 5/18/94 0:00 5/19/94 0:00 D 03 5/20/94 0:00 g 5/21/94 0:00 CD 5/22/94 0:00 5/23/94 0:00 5/24/94 0:00 5/25/94 0:00 5/26/94 0:00 5/27/94 0:00 5/28/94 0:00 5/29/94 0:00 5/30/94 0:00 5/31/94 0:00 6/1/94 0:00 672/94 0:00 6/3/94 0:00 6/4/94 0:00 H 1 1 1 1 h H 1 1 1 1 1 1 1 1 H H 1 1 1 1 h "1" II Hi—i-n— IV-3. Station S3 Submersion of the current meter at station S3 occurred 56% of the total sampling time usually for 8 to 16 hours per inundation. One-minute-averaged velocities range from 5.86 to 15.37 cm/s with a mean value of 10.32 cm/s (Figure 99). Values are highest through the sampling intervals June 9 (1900 h) to June 10 (0200 h) and June 26 (1900 h) to June 27 (0300 h) with currents averaging 13.86 and 15.37 cm/s, respectively. In addition, one-minute-averaged currents are high (above 12 cm/s) in 6 other intervals throughout the survey. Measured velocities coincide well with the tidal range curve with the highest velocities recorded in the spring tides. Wave particle velocities at station S3 exceed 35 cm/s 71 times in the study period with 61 of these values recorded in a flooding direction (-50-100°). Currents over 40 cm/s are reached 22 times with only 1 of these values recorded in an ebbing direction (~260-320°). Currents exceed 40 cm/s on June 6 (1700 h) to June 7 (0900 h), June 8 (1800-2000 h), June 19 (0500-0700 h), June 19 (1500 h) to June 20 (0700 h), June 20 (1600-1700 h), and June 23 (1800-1900). The maximum wave particle velocity was recorded in the interval on June 20 (1600-1700 h) and reached a value of 47 cm/s. Wave particle velocity measurements for the June 6 interval are shown in Figure 100 and represent a typical inundation period where current velocities are high. In general, flooding current velocities exceed ebbing velocities, however, high ebbing velocities are observed when velocities over the inundation period are lower. The peak for the flooding velocities are not only higher but the velocities are more focussed in one direction. The ebbing velocities are lower and occur over a wider range of directions. Current velocities of 80 cm/s, the critical shear velocity for erosion at station S3, are never reached at any time in the sampling period. 196 L61 Current speed (cm/s) 6/1/93 0:00 6/3/93 0:00 hjj 6/5/93 0:00 era" c i-i CD vo 6/7/93 0:00 vo O : C? 6/9/93 0:00 P c CD 6/11/93 0:00 % -CD i •n TO 6/13/93 0:00 CD CL < CD_ 8 6/15/93 0:00 j CD 3" 5? 0 i O 6/17/93 0:00 + & CD § 6/19/93 0:00 P o £ 6/21/93 0:00 C ' p CD vo 6/23/93 0:00 vo LO £ 6/25/93 0:00 P 6/27/93 0:00 6/29/93 0:00 + 7/1/93 0:00 (tu) vfim |BPLL The plot of currents averaged over 10° increments shows a strong bidirectional flow towards -70-90° (flooding) and -230-250° (ebbing) (Figure 101). Currents in a flooding direction not only occur more often but display higher average velocities (-17.5 cm/s) than currents in an ebbing direction (-13 cm/s) which is consistent with the wave particle velocity observations. Like the wave data, the flooding peak is more focussed towards high velocities in a consistent direction whereas, the ebbing peak is more broad with lower speeds over a wider range of directions. Currents in directions other than the flood and ebb generally average 4-6 cm/s. Water temperatures vary less throughout the survey than at stations S1 and S2, ranging from 14.5° on June 6 to 20.5°C on June 19 (Figure 102). Temperatures start at 18°C and fall to 4°C by June 10. They increase until June 19 and then decrease to 17°C by June 22 where they increase slightly until the end of the month. Temperatures within a sampling inundation only vary slightly with a maximum variation of 3.5°C. Like temperature, salinity does not vary as markedly as stations SI and S2. Values at station S3 range from 2.5%o to 15.5%o (Figure 103). The trend in salinity values follows that found at station 1 with an increase from the beginning of June to a peak on June 9 and a drop in value to June 13. A second increase occurs until June 22 and then salinities fall until the end of the survey. The pattern is indicative of spring/neap tidal effects. The largest degree of variation in salinity over a single inundation period occurs on the falling limbs of the salinity peaks. The valleys and the rising limbs show the lowest degree of variability over a single current meter submersion because the instrument is inundated for less time in lower high tides and therefore is more likely to experience well mixed water with less variation throughout the inundation. 199 Station 3, June 3 - June 30, 1993 current speed averaged over 10° intervals and frequency of flow directions over 10° intervals CO E o, T J 0 0 a CO m I O L O L O mm mmLomm I O L O U O m m m m m m I A in LOioinioioio m m in m m m rr rj rr rf rf •— CN CO rf If) rr rr rf rr rf rr oo O O •— OJ co rf rf rf rf rf rf tf> -O rv co o rf rf rf rf 10 .0 8.0 -J > . 6 .0 O C 0 13 D" 0 LL 4 .0 —I 2.0 Calculation Method Frequency Class Interval 10 Degrees Population 14440 Maximum Percentage.9.4 Percent Mean Percentage 2.8 Percent Standard Deviation 2.4 Percent Vector Mean 142.84 Confidence Interval 2.01 Degrees R-mag 0.32 o o o o o o _ W ^ « <l o o o o o o o o o C O O O . - C M O ' t W o o o o o o o o o o o o o o o o o o o o o •or^cooO'— cNm*ji/)-o^-coo o .— O J to *t *n o C M C M C N C N C N C N t C N C M C N C M C O C O e O C O C O O C O Direction (°) Figure 101: Average speed and direction plotted over 10 degree-averaged increments at station 3 200 103 Temperature (degrees Celcius) CTQ C O to n 1-1 CO 3 >g ro >-) u c < g I— -o H ro 3 o o c ro s o p a ro 5 3 CD 6/3/94 0:00 6/4/94 0:00 6/5/94 0:00 6/6/94 0:00 6/7/94 0:00 6/8/94 0:00 6/9/94 0:00 6/10/94 0:00 6/11/94 0:00 6/12/94 0:00 6/13/94 0:00 6/14/94 0:00 6/15/94 0:00 + 6/16/94 0:00 6/17/94 0:00 6/18/94 0:00 6/19/94 0:00 6/20/94 0:00 6/21/94 0:00 6/22/94 0:00 6/23/94 0:00 6/24/94 0:00 6/25/94 0:00 6/26/94 0:00 6/27/94 0:00 6/28/94 0:00 6/29/94 0:00 6/30/94 0:00 + —(— H— -J —(  CO to H— .. •": W , ' •ftp 7/1/94 0:00 >T1 C a> O oo o "I CD o D 3-o vo vo UJ o UJ D CD 3 CD 6/3/94 0:00 6/4/94 0:00 6/5/94 0:00 + 6/6/94 0:00 6/7/94 0:00 + 6/8/94 0:00 6/9/94 0:00 6/10/94 0:00 6/11/94 0:00 6/12/94 0:00 6/13/94 0:00 6/14/94 0:00 6/15/94 0:00 6/16/94 0:00 6/17/94 0:00 6/18/94 0:00 6/19/94 0:00 6/20/94 0:00 6/21/94 0:00 6/22/94 0:00 6/23/94 0:00 6/24/94 0:00 6/25/94 0:00 6/26/94 0:00 6/27/94 0:00 6/28/94 0:00 6/29/94 0:00 6/30/94 0:00 Z0Z Salinity (ppt) —(— 03 —f— O - t — -t— H— I lllj • Wm M T M II r ^ i ^ f > i H • - — x — * 7/1/94 0:00 Salinity varies on a single submersion period by up to 10%o but typically varies between 0.5 and l.5%o. IV-4. Station S4 The current meter deployed at station S4 in the month of May experienced full submersion 72% of the sampling period usually for 18 hours per interval. The one-minute-averaged velocities measured at station S4 for this month ranged from 10.45 to 17.78 cm/s and were highest on sampling intervals May 23 (1600 h) to May 24 (1000 h) and May 28 (1800 h) to May 29 (0600 h) (Figure 104). Superimposing the tidal range curve on this figure demonstrates that there is little relation between the tidal cycle and the current velocities measured at station S4 in May. For the deployment in the month of June the current meter was submersed for 76% of the time and again for usually 18 hours per interval. The highest one-minute-averaged velocity was 19.89 cm/s with the lowest being 9.17 cm/s and the average being 13.52 cm/s (Figure 105). The highest values occurred through sampling intervals June 24 (1700 h) to June 25 (0300 h) and June 25 (1700 h) to June 26 (0300 h) with values of 18.86 and 19.89 cm/s, respectively. Superimposing the tidal range curve on the measured velocities shows slightly better consistency than the May curve, with the highest velocities occurring on the spring tides as expected. Wave particle velocities in the month of May exceed 40 cm/s 47 times with 44 of these values recorded in a flooding direction (-30-60°). The critical shear velocity for erosion at station S4 is 49 cm/s and it is reached only once in May in an ebbing direction. The highest single velocity reached was -50 cm/s on May 11 (2000 h) to May 12 (1100 h) in and ebbing 203 toz Current speed (cm/s) cn co 5/1/93 0:00 5/3/93 0:00 4-5/5/93 0:00 5/7/93 0:00 5/9/93 0:00 5/11/93 0:00 5/13/93 0:00 5/15/93 0:00 5/17/93 0:00 5/19/93 0:00 5/21/93 0:00 + 5/23/93 0:00 5/25/93 0:00 5/27/93 0:00 5/29/93 0:00 + 5/31/93 0:00 + 6/2/93 0:00 6/4/93 0:00 (ui) lufoeu. I B P L L £0Z Current speed (cm/s) 31 era' c o L/> O D a c CD 1 P < CD >-l P CTQ CD P -< o" o I 13 O «—I c 3 CD VO VO u> ft ft o 3 o 6/1/93 0:00 + 6/3/93 0:00 6/5/93 0:00 6/7/93 0:00 6/9/93 0:00 6/11/93 0:00 6/13/93 0:00 6/15/93 0:00 CD* 3 0 5 6/17/93 0:00 6 CD 6/19/93 0:00 6/21/93 0:00 6/23/93 0:00 6/25/93 0:00 6/27/93 0:00 6/29/93 0:00 7/1/93 0:00 (LU) JU.6J9U. I B P L L direction (Figure 106). Currents in a flooding direction in this interval are also high. Typically the flooding current velocities exceed the ebb, however, in some cases the ebbing velocities may be higher. Wave particle velocities for the month of June are significantly higher than the month of May at station S4. Velocities exceed 40 cm/s 125 times with 110 of these values recorded in a flooding direction. The maximum single velocity recorded occurred on the interval of June 4 (1500 h) to June 5 (0800 h) with a value of 53 cm/s in flooding direction (Figure 107). The critical shear velocity for erosion of 49 cm/s is reached 12 times in June, always in a flooding direction. Only 4 of the sampling intervals recorded show ebbing velocities greater than flooding velocities. Current plots averaged over 10° increments for the month of May confirm this observation as flooding currents are higher (22 cm/s) and more concentrated in one direction than ebbing currents (-190-250°) which are lower (18 cm/s) and spread out in a wider range of directions (Figure 108). Velocities in other directions are typically 7 cm/s. The frequency of occurrence of directions shows that ebbing currents occur more often than flooding currents suggesting that on a flooding tide the water moves onto the bank quickly resulting in higher velocities for shorter durations, while on an ebbing tide, the water moves off the bank at a slower rate resulting in lower velocities for longer durations. Current plots averaged over 10° increments for June show a similar distribution pattern to the month of May (Figure 109). Hooding currents (-30-60°) are higher (24 cm/s) and more focussed in one direction than ebbing currents (-210-250°) which are lower (18 cm/s). Velocities in other directions are consistent with the May results of 7 cm/s. However, unlike the May results, the frequency of occurrence of both the flooding and ebbing directions is approximately equal. This is supported by the 206 I 1 1 1 1 1 I I I 1 1- o o u n o i n o m o m o m o l O t M - C O C O C M C M i - T -(s/iuo) paads iiiauno 207 I 1 1 1 1 1 1- o o o o o o o o to in •* co CM T -(s/uuo) peads juauno 208 Station 4, May 7 - June 3, 1993 current speed averaged over 10° intervals and frequency of flow directions over 10° intervals H 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 h H 1 1 1 1 f- H 1 1 h H 1 1 1 1 ui m io m m m m m m m i o l o i n i o i o i o i o i o i o i o i o i o i n i o i n o i o i n u o m l o i o m m u ? m T T I •— CO TJ UJ O O O O 1— CN T J I O TT 1 10.0 8.0-\ >-6.0 O C 0 cr 0 Li- 4.0 2.0-1 Calculation Method Frequency Class Intervql 10 Degrees Population 15880 Maximum Percentage.8.7 Percent Mean Percentage 2.8 Percent Standard Deviation 2.35 Percent Vector Mean 246.67 Confidence Interval 10.41 Degrees R-mag 0.06 o o o o o o o o o o .— C M c O T J i O " O r ^ c O O o o o o o o o o o o o o o o o o o o o o o o Direction (°) Figure 108: Average speed and direction plotted over 10 degree-averaged increments at station 4 in May 209 Station 4, June 3 - June 30, 1993 current speed averaged over 10° intervals and frequency of flow directions over 10° intervals co E o_ TJ 0 0 a CO m l O i o m i o i o i o m m i o i o l o i o i o t n m i o i o i o t o m i o i A t o t o i o i o m i o i o i o i o m m m m ( - l _ l _ p . ^ P . ^ 1 _ P . p . ( N l N W W « t N l N r N t M C M ( 0 ( 0 ( O P ) n n 10.0 8.0 > 6.0-1 o c 0 a 0 ul 4.0-\ 2.0 CalculaHon Method Frequency Class Interval 10 Degrees Population 17960 Maximum Percentage.8.7 Percent Mean Percentage 2.8 Percent Standard Deviation 2.51 Percent vector Mean 259.04 Confidence Interval 9.56 Degrees R-mag 0.06 o o o o o o o o o p o o o o o o o o o o o o o o o o o o o o o o o o o o o ^ CN -<j m i— co c> o •— C N t o ^ j m o r ^ r o o - O i — C N n * j m - o r ^ c o o o — C N to *^  m -o -— C M C M O I C M C M C M C M C M C M C M CO CO CO W ( O ( O P ) Direction (°) Figure 109: Average speed and direction plotted over 10 degree-averaged increments at station 4 in June 210 observation that the velocity peak in the ebbing direction is sharper for the month of June than for the month of May. Temperature measurements recorded in the month of May range from 10°C on May 13 to 19°C on May 30 (Figure 110). Temperatures at the beginning of May are 12°C and increase to 18.5°C by May 19, decrease to 13°C by May 22, gradually increase to 19°C by May 30 and fall to 16° until the end of the survey. This temperature trend follows very closely to that observed at station 1 and represents the spring and neap tidal influences. Temperatures within a single sampling inundation show a maximum variation of 4.5°C but typically vary 1 to 2°C. Temperature variation for the month of June is significantly less than the month of May ranging from 14.5 to 20.5°C (Figure 111). Temperatures at the beginning of June are approximately 16°C, fall to 14.5°C by June 10 before rising to 20°C on June 12 and falling to 16°C by June 14. A slow increase in temperature takes place until June 20 when values reach 20°C again before falling to 16°C on June 23. A gradual increase in temperature occurs until the end of the month. Within interval temperature variation is minimal in June with typical values of less than 1°C in an inundation. The maximum variation in a single submersion was 5°C. Salinity measurements at station S4 in May are 22%o at the beginning of the survey and increase to 28.5%o by May 13 before falling to 3%o by May 19 (Figure 112). From May 15 to the end of the survey salinities vary over each inundation interval by an average of 9%o over a range of 3%o to 19%o so any peaks in salinity after this date are being obscured by the large variation within each sampling interval. Not only is the pattern indicative of spring and neap tidal influences but also of Fraser River freshet influence. Salinity values vary over a tidal inundation by as much as 16%o and generally show an increase as deeper, more saline water approaches 211 ZIZ Temperature (degrees Celsius) 21 era' B 8 3 CD a <: o 3 o 3 3" O VO o 3 a 0 f—¥-CD 3 CD 5/7/93 0:00 5/8/93 0:00 5/9/93 0:00 5/10/93 0:00 5/11/93 0:00 5/12/93 0:00 5/13/93 0:00 5/14/93 0:00 5/15/93 0:00 5/16/93 0:00 5/17/93 0:00 5/18/93 0:00 5/19/93 0:00 5/20/93 0:00 5/21/93 0:00 5/22/93 0:00 5/23/93 0:00 5/24/93 0:00 5/25/93 0:00 5/26/93 0:00 5/27/93 0:00 5/28/93 0:00 5/29/93 0:00 5/30/93 0:00 5/31/93 0:00 6/1/93 0:00 6/2/93 0:00 6/3/93 0:00 —I— -I— —r— H - H — oo H — to o 1 * I* * f t HI 6/4/93 0:00 Temperature (degrees Cels ius) 31 c 3 P ro CD 3 -1 p o' 3* 5* co 3 o 3 c 3 CD P o 3 • % 3 CD 673/94 0:00 674/94 0:00 6/5/94 0:00 6/6/94 0:00 6/7/94 0:00 6/8/94 0:00 6/9/94 0:00 6/10/94 0:00 6/11/94 0:00 6/12/94 0:00 6713/94 0:00 6/14/94 0:00 6/15/94 0:00 6/16/94 0:00 6/17/94 0:00 6/18/94 0:00 6/19/94 0:00 6/20/94 0:00 6/21/94 0:00 6/22/94 0:00 6/23/94 0:00 6/24/94 0:00 6/25/94 0:00 6/26/94 0:00 6/27/94 0:00 6/28/94 0:00 6/29/94 0:00 6/30/94 0:00 M 01 I I —I r— CO C D H r— IV) o ro ro M y 7/1/94 0:00 Tl GO & 3' 5 ° 0 CD 1 | g 3 p* CD vo vo 09 M • o D 5/7/93 0:00 5/8/93 0:00 5/9/93 0:00 5/10/93 0:00 5/11/93 0:00 5/12/93 0:00 5/13/93 0:00 5/14/93 0:00 5/15/93 0:00 5/16/93 0:00 5/17/93 0:00 5/18/93 0:00 5/19/93 0:00 5/20/93 0:00 5/21/93 0:00 5/22/93 0:00 5/23/93 0:00 5/24/93 0:00 5/25/93 0:00 5/26/93 0:00 5/27/93 0:00 5/28/93 0:00 5/29/93 0:00 5/30/93 0:00 5/31/93 0:00 6/1/93 0:00 6/2/93 0:00 6/3/93 0:00 PIZ Salinity (ppt) ro o-> - t — o H— 4> -r-a - I — CO -r-ro CO o XX 1 F = ^ffl— ^ n^i„ -HI « III 1 • 6/4/93 0:00 followed by a decrease as the water shallows. The depth at station S4 allowed the current meter to be submersed for two flooding tides without exposure during the high-low tide between them on many occasions. Like temperature, salinity measurements recorded in June, are much less variable than in May, ranging from 1.5 to 17.5%o (Figure 113). A slight peak in salinity occurs on June 9 to 17.5%o followed by a drop to 1.5%o on June 12. A gradual increase to \7.5%o by June 21 precedes a slight decrease to I6%c to the end of the survey. Similar to May results, salinity varies over a submersion period significantly and therefore masks the effects of salinity variation over the spring and neap tides. The maximum salinity variation over a single inundation was 14%o. The current meter at station S4 was equipped with a pressure sensor which recorded depth. Depth measurements demonstrate the effect of spring and neap tides in the month of May (Figure 114) as depth during a spring tide varies more significantly than depth during a neap tide. Depth ranged from 0.6 m above the sensor, located at the midpoint of the current meter with the speed and direction electrodes (-50 cm from the seabed), to 2.75 m. Depth measurements recorded in June at station S4 show the spring and neap tidal cycle but also display a larger depth range than in May (Figure 115). The maximum depth over the sensor for the month of June was -2.75 m, similar to May, however, this depth is recorded on both spring tides in June but only one spring tide in May. Prior to May 19, depths do not exceed 2 m over the sensor. This may be the result of the increase in the volume of water arriving from the mouth of the Fraser and/or the slight increase in spring tidal height in the month of June. 215 T1 Cfq c 3 O J EL 5' ta 5' » CD 1 | S- <D c D a VO VO ft o 3 673/94 0:00 6/4/94 0:00 6/5/94 0:00 6/6/94 0:00 6/7/94 0:00 6/8/94 0:00 6/9/94 0:00 6710/94 0:00 6/11/94 0:00 6/12/94 0:00 6/13/94 0:00 6/14/94 0:00 6/15/94 0:00 6/16/94 0:00 6/17/94 0:00 6/18/94 0:00 6/19/94 0:00 6/20/94 0:00 6/21/94 0:00 6/22/94 0:00 6/23/94 0:00 6/24/94 0:00 6/25/94 0:00 6/26/94 0:00 6/27/94 0:00 6/28/94 0:00 6/29/94 0:00 6/30/94 0:00 913 Salinity (ppt) X — NK • i n —*-*— 7/1/94 0:00 LIZ Depth at station 4 (m) 5/1/93 0:00 5/3/93 0:00 5/5/93 0:00 5/7/93 0:00 5/9/93 0:00 5/11/93 0:00 5/13/93 0:00 5/15/93 0:00 5/17/93 0:00 + 5/19/93 0:00 5/21/93 0:00 5/23/93 0:00 5/25/93 0:00 5/27/93 0:00 5/29/93 0:00 5/31/93 0:00 6/2/93 0:00 + 6/4/93 0:00 (ai) iij&eii lepu. on C 3 CB 6/1/93 0:00 6/3/93 0:00 6/5/93 0:00 • f l 6/7/93 0:00 era a 3 6/9/93 0:00 6/11/93 0:00 D CD •a 5 6/13/93 0:00 o" a O 1 6/15/93 0:00 CD g g CD 5 6/17/93 0:00 a a* o 6/19/93 0:00 v § 6/21/93 0:00 OJ cn £ 6/23/93 0:00 5' : a 6/25/93 0:00 6/27/93 0:00 6729/93 0:00 7/1/93 0:00 SIZ Depth at station 4 (m) o cn -+- to -f— IV) bi - r — (LU) iL|6!9M IBPLL IV-5. Station S5 The current meter deployed at station S5 through the month of June was inundated 77% of the time, similar to the submersion time of the current meter deployed at station S4 through June. Inundation intervals were usually for 19 hours. One-minute-averaged velocities ranged from a low of 10.81 cm/s to a high of 18.12 cm/s with an average value of 14.01 cm/s (Figure 116). The highest velocities were recorded in sampling intervals June 3 (1400 h) to June 4 (0900 h), June 4 (1400 h) to June 5 (0900 h), and June 24 (1600 h) to June 25 (1300 h) with values of 18.12,17.47 and 17.90 cm/s, respectively. Superimposing the tidal range curve on the measured velocities reveals a good relationship with peaking velocities in spring tides. Wave particle velocity measurements at station S5 exceed 50 cm/s 32 times throughout the survey with 28 of these values recorded in a flooding direction. The maximum velocity recorded at this station was 62 cm/s in an ebbing direction in both sampling intervals June 6 (2300 h) to June 7 (1000 h) (Figure 117) and June 19 (0400-0800 h) (Figure 118). Typically the flooding velocities are higher than the ebb with some exceptions. The critical shear velocity for erosion at station S5 is 58 cm/s and it is reached 6 times in the sampling period. Although the critical shear velocity is reached an equal number of times in a flooding and ebbing direction, the ebbing velocities are 4 cm/s higher than the flooding velocities. Averaging speed and direction measurements over 10° increments shows that current velocities in flooding directions exceed these in ebbing directions with peak values of 23 cm/s and 18 cm/s, respectively (Figure 119). As seen previously, the peak in velocity in the flooding direction (70-100°) is more focussed in one direction whereas the peak in the ebb direction (220-270°) is broader, encompassing a wider range of directions. In contrast to measurements made 219 Tidal height (m) r 00:0 86/l/Z 00:0 E6/6Z/9 00:0 E6/ZZ/9 00:0 E6/S2/9 00:0 E6/B2/9 00:0 E6/IZ/9 00:0 E6/61/9 00:0 E6/Z1/9 00:0 £6 /91 /9 00:0B6/EL/9 00:0E6/U/9 00:0 E6/6/9 00:0 E6/Z/9 00:0 E6/S/9 00:0 E6/E/9 00:0 £6/1 /9 (S/UJO) paeds juejjno 220 \ (S/LUO) peads jua j jno 222 Station 5, June 3 - June 30, 1993 current speed averaged over 10° intervals and frequency of flow directions over 10° intervals o io i n i o i f t i o t o i o m t o i o m i n i o i o i o i o i o < / > i o i o i o i o t o i / > t o i o i o i A i O L r > tDiom m m m f~ ot co *3 ir> -o co o o i- w n o r-. co o o >— CM co in >o rs. co o o CN co *r m 1— — ^- .— r - r - r - F - r - C M C M C M C M C M C M C M C M C M C M C O C O C O C O C O C O Calculation Method Frequency Class Interval 10 Degrees Population 20800 Maximum Percentage. 10.8 Percent Mean Percentage 2.8 Percent Standard Deviation 2.54 Percent Vector Mean 116.86 Confidence Interval 2.47 Degrees R-mag 0.22 CM 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 t— p - r - r - r - r - r - r - r - r - O J C N C N C N C N O I C N C N C N C N CO CO CO O CO CO CO Direction (°) Figure 119: Average speed and direction plotted over 10 degree-averaged increments at station 5 223 in May at station S4, the frequency of occurrence of flooding directions is much greater than ebbing directions, likely due to the shape of the bank. Like station S4, currents in directions other than ebb and flood, have velocities of ~7 cm/s. Temperature varies from 12.5 to 19.5°C over the whole sampling period and in a single sampling interval (Figure 120). This 7° interval variation was also found at station S2 and is the largest temperature variation recorded in one interval. Temperatures are 16°C at the beginning of June, fall to less than 13°C on June 9, rise slowly and with minor fluctuations to 19.5°C on June 20 and fall in the same sampling interval to 12.5°C by June 21. Temperature rises steadily to 18°C until the end of the survey. Salinity varies from 2 to 25.5%o with little evidence of salinity peaks because of the large variations in salinity values within sampling intervals (Figure 121). Slight peaks near June 5 and June 21 are evident with salinity lows near June 10 and June 27. This corresponds roughly with the spring/neap tidal cycle. The maximum salinity variation in one current meter submersion is 19%0. IV-6. Station S6 The deployment of the current meter situated at station S6 resulted in inundation for 75% of the sampling time, similar to stations S4 and S5 submersion for the month of May and June. However, averaged velocities at station S6 are considerably higher, reaching values of 27.8 cm/s in the interval recorded on May 11 (1900 h) to May 12 (0100 h) (Figure 122). Average velocities are lowest on the interval recorded on May 14 (1000-1500 h) with a value of 9.63 cm/s but are above 20 cm/s on 6 other sampling intervals. Velocities measured at station S6 show only a 224 SZZ Temperature (degrees Cels ius) 31 era' c a CD •i i—i-rt i rs 1-1 pa 3 g 5 g D s © n 3 3 CD o 3 v o L O o L f l 6/3/94 0:00 6/4/94 0:00 6/5/94 0:00 6/6/94 0:00 6/7/94 0:00 6/8/94 0:00 6/9/94 0:00 6/10/94 0:00 6/11/94 0:00 6/12/94 0:00 6/13/94 0:00 6/14/94 0:00 + 6/15/94 0:00 6/16/94 0:00 + 6/17/94 0:00 6/18/94 0:00 6/19/94 0:00 6/20/94 0:00 6/21/94 0:00 + 6/22/94 0:00 6/23/94 0:00 4-6/24/94 0:00 | 6/25/94 0:00 6/26/94 0:00 6727/94 0:00 6/28/94 0:00 6/29/94 0:00 6730/94 0:00 7/1/94 0:00 * xf i j j k ^ r : — m 7/2/94 0:00 cfq' — 1-1 CD to 00 EL 5' < 1 o 3 Cfl o> Ft o 5-o <—I C 3 CD VO vo tt et-Cfl r-r £ 0 t—r I— • o 3 L/> • r—t-CD CD 6/3/94 0:00 6/4/94 0:00 + 6/5/94 0:00 6/6/94 0:00 6/7/94 0:00 6/8/94 0:00 6/9/94 0:00 6/10/94 0:00 6/11/94 0:00 6/12/94 0:00 6/13/94 0:00 6/14/94 0:00 6/15/94 0:00 6/16/94 0:00 6/17/94 0:00 6/18/94 0:00 6/19/94 0:00 6/20/94 0:00 6/21/94 0:00 6/22/94 0:00 f 6/23/94 0:00 6/24/94 0:00 6/25/94 0:00 6/26/94 0:00 6/27/94 0:00 6/28/94 0:00 6/29/94 0:00 6/30/94 0:00 7/1/94 0:00 | 9Z2 Salinity (ppt) ro ro o ro +—+ h Htt--u r -n n 1111 MMHBfesBaaaaaawMM -• #——| • • -H (f-tf TT*1 7/2/94 0:00 Tidal height (m) 00:0 B6/W9 00:0 £6/2/9 + 00:0 E6/I-E/9 00:0 66/62/9 00:0 E6/Z2/9 00:0 £6/92/9 00:0 E6/E2/9 + 00:0 £6/12/9 00:0 £6/61/9 00:0 E6/Z US + 00:0 £6/9179 00:0 E6/EI/9 00:0 £6/1-179 00:0 £6/6/9 00:0 E6/Z/9 00:0 E6/9/9 00:0 E6/E/9 00:0 E6A/9 VO CS o -•—• m ON o c o a 5 ® <» E o > -a a> 00 c<3 V l 1 a CD e O CN CN <U 3 E (s/Luo) peeds juejjno 227 minor relation to the tidal cycle, however higher values are generally found in the spring tides. Wave particle velocities at station S6 exceed 50 cm/s 96 times with 56 of these values recorded in a flooding direction (~60-110°) with ebbing velocities (230-290°) maintaining a higher influence than at the stations previously discussed. Several sampling intervals show higher ebbing than flooding velocities at station S6. The highest single velocity recorded at station S6 was 90 cm/s in the sampling interval of May 11 (1900 h) to May 12 (1300 h) (Figure 123). Velocity measurements on the ebbing tide show currents over 60 cm/s 11 times while on the flooding tide these velocities are only reached 6 times. Currents reach 56 cm/s, the critical shear velocity for erosion of sediments at this station, 56 times during the sampling period with 32 of these occurrences in flooding directions. Despite the more frequent occurrence of eroding currents in the flooding direction, the eroding ebbing currents are typically 10 to 20 cm/s higher than the flooding currents. The greater influence of ebbing directions is evident when examining the plot of speed and direction averaged over 10° increments (Figure 124). Ebbing currents are slightly higher (24 cm/s) than flooding currents (23 cm/s), however flooding currents ar longer in duration than ebbing currents. Current velocities in directions other than the ebb and flood, measure 12 cm/s, significantly higher than the other stations on the bank. Temperature measurements show a variation from 9°C on May 13 to 17.5°C by May 19 (Figure 125). Temperatures decrease after May 19 to 11.5°C by May 20 and then increase slowly to 16.5°C by May 28 where they remain stable until the end of the survey. This is consistent with other measurements recorded in May and demonstrate the influence of both the Fraser River freshet and the spring/neap tidal cycle. Temperature variations over one inundation interval are 228 o CD O m o o CO o CM (S/LUO) pasds juajjno 229 Station 6, May 7 - June 3, 1993 current speed averaged over 10° intervals and frequency of flow directions over 10° intervals U ) i r O U ) i O L O i O L O k O L O L O i O LO LO lO L O L O L O L O L O L O L O L O L O L O L O L O L O L O L O L O U) U) lO LO LO lO >— CN rO i »j M »j T «j r r T J T J T J T J T J T J O •— CN CO CO O O — CN CO T J T J T J T J T j T J T j T j T J T J T J T J T J T j C N C N C N C N C N C N C N C N C N C N CO CO CO CO CO CO 1 0 . 0 8.0 - 6 . 0 o C CD O* 2 4 . 0 2 .0 Calculation Method Frequency Class Interval 10 Degrees Population 20010 Maximum Percentage.7.7 Percent Mean Percentage 2.8 Percent Standard Deviation 1.84 Percent vector Mean 126.02 Confidence Interval 3.29 Degrees R-mag 0.17 o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o . — CM CO T J to O O O O i— CN co T J 10 C O C O CO C O C O C O Direction (°) Figure 124: Average speed and direction plotted over 10 degree-averaged increments at station 6 230 00:0 fr6/W9 00:0 f 6/E/9 00:0 fr6/2/9 00:0 t-6/179 00:0 f6/t£/9 OO-'O V6/0E/S t 00:0 fr6/62/9 00:0 V6/82/9 + 00:0 W/Z2/9 00:0 W/92/9 00:0 fr6/92/9 00:0 fr6/t>2/9 00:0 f 6/B2/9 00:0 *6/22/9 00:0 fr6/1-2/9 00:0^ 6/02/9 £ t 00:0^ 6/61/9 00:0*6/81/9 oo-ote/zt/s 00:0 W/9,/9 00:0^ 6/91-/9 t 00:0 f6/H/9 00=0 V6/E1/9 00:0^ 6/21/9 00:0fr6/H79 00:0*6/01-/9 00:0 t-6/6/9 00:0 f 6/8/9 00:0 P6/L/S CD E CO vo a o cn C O u •£ >-. «s C O • •-< +-» PS i > g rt U £ rt CN 3 t o (smsieo saaj6ap) ajniejadiuai 231 generally low until May 19, averaging 2°C, and then increase with a maximum variation of 6.5°C. Salinity varies similarly to temperature but reciprocated. Salinities are up to 30%o at the beginning of May and decrease until May 18 (Figure 126). From May 18, salinity values through single sampling intervals show a high degree of variation and therefore obscure the effects of the flood/neap tides. Variations within sampling intervals before May 18 range from l%o to 13%o while after May 18, salinity variations are commonly 18%o and higher with a maximum variation of21%0. IV-7. Station Sll The current meter deployed at station Sll was submersed 82% of the total sampling period, the most of any in the study, and was usually covered for 19 hours per interval. The one-minute-averaged velocities at station Sll range from 9.68 to 17.76 cm/s with an average of 13.46 cm/s (Figure 127). The highest velocity was recorded in the sampling intervals June 4 (1400 h) to June 5 (0900 h), June 6 (1500 h) to June 7 (1100 h), and June 24 (1600 h) to June 25 (0400 h) with values of 16.26,16.80, and 17.76 cm/s, respectively. The tidal range curve shows a good relationship with measured velocity values with the highest velocities on the spring tides and an obvious low on the neap tide. Wave particle velocity measurements at station Sll exceed 40 cm/s 57 times and occur evenly in the flooding and ebbing directions. The maximum velocity measurement was 53 cm/s in ebbing and flooding directions in the sampling intervals on June 4 (1400 h) to June 5 (0900 h) and June 5 (1500-1700 h) (Figure 128). Slightly higher velocity values occur in the flood 232 I ' II-)( W *w- -X-* X X X X M XKK X XK > -x X HP JHr-q^ t m torn — X <::;W.v,.^-.--: ....... v.-. ---•»4|fi£§y§i& -Ui—#- , , O 0 0 CO CM CO CM CM CM CM O CM ( j d d ) A;!U!|ES 233 00:0 V6/m 00-0 fr6/E/9 00:0 fr6/Z/9 oo-o wi/9 oo-o f6/i.e/s 00:0 W/0e/9 t 00:0 W/62/9 CXCO fr6/82/9 00:0 t>6/Z2/9 CX):0 f 6/92/9 00:0 f 6/92/9 00:0 W/frZ/S 00-0 W/E2/9 00:0 P6/ZZ/S 00-0 fr6/l2/9 00:0 fr6/02/9 00:0fr6/6l/9 - 00:0f6/8l/9 00:0fr6//l/9 00:0^ 6/91/9 00:0f6/9l/9 00:0^ 6/^ 1/9 | 00:0f6/El/9 \ 00:0f6/2l/S 00:0f6/H-/9 t 00:0fr6/0l79 00:0 fr6/6/9 00:0 WB/S 00:0 *6/Z/9 CD E CD • cd Q vo c O c3 *•-» (fl m ON ON <4-H o CU C O • ^  a m CN 3 Tidal height (m) o f 00:0 E6/L/Z 00:0 £6/62/9 00:0 E6M2/9 00:0 £6/92/9 00:0 E6/E2/9 00:0 E6/L2/9 00:0 E6/6L/9 00:0 E6/ZL/9 00:0E6/9L/9 00:0E6/£l/9 00:0 £6/U/9 00:0 E6/6/9 00:0 E6/Z/9 00:0 £6/9/9 + 00:0 E6/E/9 00:0 E6/L/9 CD E c o m OS OS 3 3 1—> <+-! O I •a a u O > 60 ca 3 e e O 3 (s/ujo) peeds juejjno 234 direction. Sediments at station Sll likely begin eroding at critical shear velocity values near 26 cm/s. Eroding currents occur more frequently in a flooding direction (1163 times out of 1735) and obtain approximately the same velocity in both flooding and ebbing directions. Currents in the flooding direction, averaged over 10° increments, measured 21 cm/s and ( were concentrated in a small range of directions (40-70°), while the ebbing currents measured 17 cm/s and occurred over a broader range of directions (200-270°) (Figure 129). Currents in other directions average 9 cm/s. The frequency of occurrence of currents in the flooding and ebbing directions is essentially equal. Temperature variations over the period of sampling at station Sll show only minor variations ranging from 12 to 19.5°C (Figure 130). Variations within a single sampling period are large, ranging from 0.5 to 5°C. In general, temperatures variations within a sampling interval are low with some exceptions. Salinity measurements do not vary significantly over the entire sampling period, however, within interval variations are high (Figure 131). The influence of the spring/neap tidal cycle is obscured by the variation within sampling intervals with a maximum range of 19%o. IV-8. Station S 1 2 The current meter deployed at station S12 was inundated for 67% of the total sampling period, usually for 17 hours per interval. The one-minute averaged velocities had a minimum value of 7.52 cm/s, a maximum value of 24.92 cm/s and an average value of 11.27 cm/s (Figure 132). The highest average velocity values at station S12 occur in the intervals May 11 (1900 h) to May 12 (0400 h) and May 12 (0600-1300 h) and reach 24.20 and 24.92 cm/s, respectively. 236 Station 11, June 3 - June 30,1993 current speed averaged over 10° intervals and frequency of flow directions over 10° intervals Direction (°) Figure 129: Average speed and direction plotted over 10 degree-averaged increments at station 11 237 j i — i — - ' " r ^ H ~ o CM 00:0 fr6/l/Z 00:0 f6/0E/9 OO'-O t-6/62/9 00:0 f6/82/9 00:0 fr6/Z2/9 00:0 fr6/92/9 t 00:0 f 6/92/9 00:0 f6/f2/9 00:0 t>6/S2/9 00:0 ^6/22/9 00:0 W/12/9 f 00:0 fr6/02/9 00:0^6/6179 00:0 t?6/81/9 00=0 W/Zr/9 00:0*6/9179 00:0 fr6/91/9 00:0 f6/t 1/9 00:0 *6 /£ 179 00:0fr6/2t/9 00:0fr6/U/9 00:0 f 6/01/9 00:0 ^6/6/9 00:0 V6/8/0 000 W/Z/9 t 00:0 P6/9/9 00-0 *6/9/9 t 00:0 fr6/W9 00-0 fr6/E/9 CD E E CD CO Q C .2 3 cn ON ON CD a =3 o c o CD J3 to Q O • — I g C3 E CD a , B •*-» I N CD € o g 0 0 (snisiao saaj6ap) a j n i B j a d i u a i 238 *—Y- &ae*< -9. x -0 0 CD OJ O J o O J (idd) AIIUHES 239 00:0 ffll/L oo-o w/oe/9 00:0 fr6/62/9 00:0 fr6/82/9 t 00:0 00:0 P6/92/9 00:0 f6/92/9 00:0 fr6/fr2/9 00:0 t-6/e2/9 00:0 fr6/22/9 -- 00=0 W/lZ/9 00:0 f 6/02/9 00:0f6/6l/9 00:0*6/8179 CD 00:0f6/Zt/9 ^ cd OOUfr6/91/9 Q 00:0*6/91/9 00:0 V6/n/9 oo:ot-6/eL/9 OOU t-6/2179 00:0 f 6/11/9 00:0fr6/0t/9 00:0 V6/6/9 t 00:0 V6/S/9 00-0 V6/Z/9 00:0 fr6/9/9 00:0 t>6/9/9 00:0 fr6/W9 00-0 f6/C/9 c o " i-H | c n ON ON u c 3 i—> O E s CD I—I c rt a > *c3 00 3 bJj Tidal height (m) CM O < h 00:0 E6/W9 00:0 £6/2/9 00:0 E6/I-E/9 00:0 £6/62/8 00:0 E6/Z2/9 00:0 £6/92/9 00:0 E6/E2/9 00:0 £6/12/9 00:0 £6/61/9 00:0 £6//1/9 + 00:0 E6/9 ITS 00:0 E6/EI/9 00:0 £6/1.1/9 00:0 £6/6/9 00:0 E6/Z/9 00:0 E6/9/9 00:0 E6/E/9 OO^O E6/179 (S/LUO) peeds luejjno 240 The tidal range curve superimposed on the measured current velocities show little relation but velocity peaks are generally found in the spring tides, with the exception of the large peak on May 11 and 12. Wave particle velocity measurements at station S12 are significantly higher than at more seaward station Sll, however this observation is made cautiously because the data were collected in different months. Wave particle velocities at station S12 exceed 40 cm/s 97 times with 56 of these values occurring in an ebbing direction. The highest velocities recorded at station S12 were reached on May 11 (1900 h) to May 12 (0400 h) (Figure 133), May 12 (0600-1300 h) (Figure 134) and May 23 (0500-0900 h) (Figure 135) with values reaching 83 cm/s on May 23 in an ebbing direction. In general, velocities in the flooding direction exceed those in the ebbing direction, however on the maximum velocity intervals described above, ebbing velocities exceed flooding velocities. The low critical shear velocity for erosion at station S12 of 33 cm/s results in sediment being eroded in both flooding and ebbing directions frequently, similar to station Sll. Eroding currents in ebbing directions reach velocities up to 20 cm/s higher than eroding currents in flooding directions although eroding flooding currents occur more often. In contrast to wave particle velocity trends, when speed and direction are plotted as averages over 10° increments, flooding velocities exceed ebbing velocities with values of 18 and 15 cm/s, respectively (Figure 136). Velocities in the flood direction (-60-100°) are focussed toward a smaller range of directions while velocities in the ebb direction (230-300°) occur in a wider range of directions. Current velocities in other directions range between 5 and 8 cm/s. The frequency of occurrence of the flooding velocities is slightly greater than the ebbing velocities, however there is strong component of flow southwards at station S12, in addition to the 241 o o o o o <tf CO CM T -(S/LUO) peeds JU9JjnQ 243 o o> o oo o o CO o o o co (S/LUO) peads ;uauno 244 Station 12, May 7 - June 3, 1993 current speed averaged over 10° intervals and frequency of flow directions over 10° intervals 1 8 T 4 + 2 -0 4-—I 1 1 1 1 1 K H 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 r—I 1 1 1 1 1 1 m m i o i o i q m t n m m i o m t n i o i n u ) i n i o t o i o > o i o i o i A t n i A i o i / > i / > i n i o i c i o i n w in i - n c n o i n ^ s o & o .— C N C O ^ r W - O t ^ C O O O * — C N C O ^ J W - O C v C O O o » — C N C O T I O . — r - r - r - — r - . — C N C N C N C N CM CM C N CM CN C N CO CO CO C O C O C O Direction (°) Figure 136: Average speed and direction plotted over 10 degree-averaged increments at station 12 245 bidirectional flooding and ebbing currents, which occurs with significant frequency. Temperature varies from 9.5°C at the beginning of the month to 17.5°C by May 24 (Figure 137). Values recorded after May 19 show a higher degree of variability within sampling intervals with the exception of the maximum variation of 6°C which occurs on May 12. Temperature trends suggest the influence of a warmer water mass by May 18 which is consistent with peak Fraser River flow. The spring/neap tidal cycle is only slightly observed through the temperature values recorded at station S12. Salinity shows the opposite trend to temperature, with values of up to 29%c at the beginning of the survey and dropping to values less than l%o by May 23 (Figure 138) with the exception of the maximum salinity variation of 19%o on May 12. Variations within sampling intervals are lower before May 19, similar to the temperature behavior. This reinforces the influence of the Fraser freshet as both a warmer and fresher water source moving onto the bank. IV-9. Station S13 Inundation of the current meter deployed at station S13 occurred 55% of the total sampling time for 7 to 15 hours per interval. One-minute-averaged velocities for each sampling interval ranged from 4.22 to 11.07 cm/s with a mean value of 7.39 cm/s (Figure 139). The highest velocities were recorded through sampling intervals June 9 (1900 h) to June 10 (0300 h) and June 23 (1800 h) to June 24 (0100 h) with values of 11.07 and 11.03 cm/s, respectively. The tidal range curve was superimposed on the measured velocities and a good relationship between peak velocities and spring tides was observed. Wave particle velocities exceed 30 cm/s 18 times throughout the sampling period, with 246 , • Mir x W " • 1 • H 1-(snjsieo seai6ap) ajniEjadwai 247 00:0 t-6/W9 00:0 f 6/E/9 00:0 fr6/2/9 00:0 WA/9 + 00:0 WM9 oo-o w/oe/9 t 00:0 W/62/9 00:0 f 6/8Z/9 00:0 V6/IZ/C 00-0 fr6/92/9 00:0 fr6/92/9 00:0 fr6/fr2/9 00:0 fr6/E2/9 OO^ O P6/ZZ/9 CD 00:0^6/12/9 ^ 00:0^6/02/9 Q 00:0*6/61-/9 00:0^6/81/9 (WO t-6/Z 1/9 00:0 f 6/91/9 00:0 W91/9 00:0fr6/H/9 00:0 fr6/E 1/9 f 00:0*6/21-/9 00:0^6/11/9 00:0*6/01-/9 00:0 f 6/6/9 00:0 f 6/8/9 00:0 P6/U9 C rt rt C O O N O N a o £ a [fl C '•3 rt 3 *-< rt E aj P, 6 o 4—' <D ^—» rt C O 0-> 3 00 -Effect "*4—i 1 N—|—|—.$_ t I — | X—X o co CO OJ -I h CM CM OJ OJ o OJ (idd) Ai!U!|BS 248 00:0 fr6/W9 00:0 *mi§ 00:0 fr6/2/9 00-0 t-6/t/9 00:0 w/ie/s 00:0 fr6/oe/s 00:0 f 6/62/S 00:0 fr6/82/9 00-0 V6/Z2/9 00:0 fr6/92/9 00:0 f 6/92/9 00:0 f 6/fr2/9 00:0 f 6/82/9 00:0 1*6/22/9 00:0 t-6/12/9 00:0 fr6/02/9 oo-ovem/s 00:0^ 6/8179 00:0W/Zt/9 00:0 f 6/91/9 00:0 f 6/91/9 00:0*6/^ 179 00:0*6/8179 00-0 f6/21/9 00:0 fr6/11/9 00:0fr6/0l/9 00:0 tV6/6/9 00:0 *6/8/9 00:0 f 6/Z/9 CD E E CD -J—" CO Q CN a _o *-» CO c/3 3 cn O N O N o e o E CD X J -t—< U c .2 a o • **H +-> <S a 0 0 m § Tidal height (m) oo;o mui 00-0 66/62/9 00:0 66/Z2/9 00:0 66/92/9 OO-'O 66/62/9 00:0 66A2/9 00:0 66/61/9 00:0 S6/LU9 CD E r— 00:0 66/91/9 00:0 66/61/9 00:0 66/U/9 t 00:0 66/6/9 00:0 66/Z/9 00:0 66/9/9 00:0 66/6/9 f 00:0 66/179 o cn c o -*—> 15 cn o\ ON cs 3 O •3 a o 0 J 5 c/3 O C) > <U OX) co1 u, I CD •4—» c •u c O 6\ 2 3 60 (S/LUO) paads luajjno 249 15 of these values occurring in an ebbing direction and those occurring in the flooding direction occurring all on the same day. The maximum velocity recorded at station S13 occurred in the interval June 6 (2200 h) to June 7 (0900 h) and reached a value of 42 cm/s in an ebbing direction (Figure 140). Typically flooding velocities exceed ebbing velocities, however, many of the maximum velocity days have higher velocities in an ebbing direction. The critical shear velocity of 57 cm/s is not reached at any time during the sampling period at station S13. When a plot of the data averaged over 10° increments is examined, the increased role of currents in the ebbing direction can be seen. Ebbing velocities average 11 cm/s in directions toward 250-300°, while flooding velocities average 10 cm/s in directions toward 50-100° (Figure 141). Velocities toward southerly directions average 6 cm/s, while velocities towards northern directions average 4 cm/s. The frequency of occurrence plot reveals ebbing velocities occur more often than flooding velocities but only to a minor extent. Temperature measurements at station 13 show values of 18°C at the beginning of June, a drop to 14°C by June 10 and a slow increase to 20°C by June 20 (Figure 142). Temperatures decrease suddenly on June 21 to 15.5°C and begin a slow increase to 18°C by the end of the survey. This pattern coincides, to a greater extent, with the spring/neap tidal cycle with the exception of the sharp temperature drop on June 21. Temperature variations within a sampling interval are small, averaging less than 2°, with the maximum variation within an interval measuring 4°C. The salinity measurements plotted over the length of the survey are much more scattered than temperature (Figure 143). Within interval-variation is large and effectively obscures salinity trends over the 4 week period, with maximum variations of 1 l%o. Salinity at station S13 ranges 250 Station 13, June 3 - June 30,1993 current speed averaged over 10° intervals and frequency of flow directions over 10° intervals Direction (°) Figure 141: Average speed and direction plotted over 10 degree-averaged increments at station 13 252 -4F=H •JUL. EJM M^HlMnWmnrmmttttrHBi o CM 00:0 *6/2/Z oo-o f6/1/1 00:0 *6/0G/9 00:0 f 6/62/9 + 00:0 f 6/82/9 00:0 *6/Z2/9 t 00-0 *6/92/9 00:0 *6/92/9 + 00:0 *6/*2/9 00:0 *6/E2/9 00:0 *6/Z2/9 1 00:0 *6/l2/9 00:0 f 6/02/9 00:0fr6/61/9 \ 00:0*6/8 m 00:0 *6/Z 1/9 00:0*6/91/9 00:0*6/9179 00:0 *6/n/9 100:0 *6/e 1/9 00:0*6/21-/9 00:0*6/U/9 00:0*6/0t/9 00:0 *6/6/9 00:0 *6/8/9 00:0 *6/Z/9 00:0 *6/9/9 + 00:0 *6/9/9 00:0 *6/*/9 00:0 *6/E/9 CD E CD 3 c5 Q cn c 0 1 ro ON ON U c 3 O a o B o a a rt > 1 S-U CU s 1-. o rt — i B 5fi (sn!S|90 saaj6ep)ejniBjadLU9i 2 5 3 -H—+-+ 4T -HW MB* -m-"^NBfrilBlf null uMif 00:0 *6/2/Z 00:0 W/W 00:0 *6/0G/9 + 00:0 *6/62/9 00:0 *6/82/9 00:0 *6/Z2/9 00:0 *6/92/9 t 00:0 *6/92/9 00:0 *6/*2/9 00:0 *6/£2/9 00:0 *6/22/9 00:0 *6/l2/9 t 00:0 *6/02/9 00:0*6/6179 00:0*6/81/9 00:0 *6/Z 1/9 + 00:0*6/91/9 00:0*6/91/9 00:0 *6/H/9 00:0*6/Et/9 00:0*6/21/9 00:0*6/H79 00:0*6/01/9 00:0 *6/6/9 00:0 *6/8/9 00:0 *6/Z/9 00:0 *6/9/9 00:0 *6/9/9 t 00:0 *6/*/9 00:0 *6/E/9 (jdd) Ayups 254 from a low of 0%o to a high of 17%o. Generally there is a drop in salinity from 10%o to 3%o by June 8 before a sharp rise to 16%o by June 10. Another drop to 0%o by June 14 is followed by a gradual increase to 14%o and then values which range from 2 to 14%o without a discernable pattern to the end of the survey. IV-10. Station S14 The current meter deployed at station S14 was fully submersed for 43% of the sampling period usually for 5 to 15 hours at a time. One-minute-averaged velocities at station S14 are slightly higher than station S13 and range from 5.66 to 20.4 cm/s with an average of 9.3 cm/s (Figure 144). The highest velocity was recorded through the sampling interval May 11 (2100 h) to May 12 (0200 h). Velocities this high are more likely to be encountered on the outer bank rather than adjacent to shore. There was a slight relationship between the tidal cycle and velocity measurements, however, slightly higher values were seen in spring tides with the value recorded on May 11 being an exception. Wave particle velocity measurements exceed 30 cm/s 72 times throughout the survey and consistently in an ebbing direction except on May 11 where wave particle velocities in the flooding direction exceed 30 cm/s 12 times. The maximum velocity recorded at station S14 was in the May 11 sampling interval with values reaching 60 cm/s (Figure 145). Current velocities in an ebbing direction dominate the wave measurements in both speed and direction at station S14. Currents at station S14 never reach the critical shear velocity for erosion value of 69 cm/s at any time in the sampling period. Plots of current speeds and directions averaged over 10° increments show a similar trend 255 Tidal height (m) 00:0 E6/W9 + 00:0 E6/2/9 00:0 E6/IE/9 00:0 E6/62/9 00:0 E6/ZZ/9 00:0 E6/92/9 00:0 E6/E2/9 + 00:0 E6A2/9 00:0 E6/6U9 00:0E6/Zt/9 00:0 £6/91/9 00:0 E6/E179 00:0 €6/1-1/9 00:0 E6/6/9 + 00:0 E6/Z/9 00:0 E6/9/9 00:0 E6/E/9 00:0 E6/I79 CD E a o c o ON ON 5? o a o a CD •*—» .2 *•<—* 'o 0 > T3 CD 00 ca u > CS 1 <D 4—» 3 a <D C O # u l-C 3 60 (S/LUO) peeds juejjno 256 to wave patterns with currents in an ebbing direction (-200-270°) reaching 15 cm/s, while currents in a flooding direction (-40-90°) reach only 10 cm/s (Figure 146). Both flooding and ebbing current velocity peaks are broad and encompass a wide range of directions, however, the peak associated with flooding directions is so broad, it is difficult to place boundaries on its limits. Currents in other directions are typically 8 cm/s. Despite higher velocities in the ebbing direction, flooding velocities occur significantly more often. In addition, currents in directions other than flood and ebb, dominate a considerable frequency of occurrence. Temperature varies from 11 to 19°C with temperatures starting at the lowest values at the beginning of the month and increasing slowly until the highest value is reached on May 21 (Figure 147). Temperatures fall to 13°C by May 22 and then increase to 18.5°C until May 28 where they fall until the end of the month to 15.5°C. Temperatures within sampling intervals vary from less than 0.5°C to 7°C with typical variations of 3°C. Maximum temperature variations within a sampling interval reach the same value as stations 2 and 5, the highest recorded in the survey. Salinity measurements recorded at station 14 show an obvious trend of decreasing values from 20%o at the beginning of the month to an average of 6%o and a low of 0%o by May 17 until the end of the survey (Figure 148). There is little evidence of the spring/neap tidal cycle influence, however there is support for the addition of a significant source of fresh water by May 17 suggesting that the Fraser freshet is playing a large role in dictating salinity values found at this station. Within interval salinity variation is 10%o, with the highest value reaching 16%o. 258 Station 14, May 7 - June 3, 1993 current speed averaged over 10° intervals and frequency of flow directions over 10° intervals •— CN CO 10.0 8.0 > 6.0 O C 0 O" CD LL 4.0 2.0 Calculation Method Frequency Class Interval 10 Degrees Population 11240 Maximum Percentage.5.9 Percent Mean Percentage 2.8 Percent Standard Deviation 0.92 Percent vector Mean 76.20 Confidence Interval 5.37 Degrees R-mag 0.14 o o o o o o o o o o o o o o o o o o o o •— CM eo T J m o o o o o r - o j c o T j m - o o o o o o o o o o o o o o o o o o 0<— C M C O T T i O - O r ^ O O O O . — C M c O - T r i O O C J C M C N C N C N C N C M C N C N C N C O c O e O C O C O C O C O Direction (°) Figure 146: Average speed and direction plotted over 10 degree-averaged increments at station 14 259 092 21 era' c i — ' ts n 1-1 «—* CD 3 CD >-i W (—• C < g r* 5' 3 CD O p o S3 VO VO r-f o 3 a 3 CD 5/7/94 0:00 5/8/94 0:00 5/9/94 0:00 + 5/10/94 0:00 5/11/94 0:00 5/12/94 0:00 5/13/94 0:00 5/14/94 0:00 5/15/94 0:00 5/16/94 0:00 5/17/94 0:00 5/18/94 0:00 5/19/94 0:00 5/20/94 0:00 5/21/94 0:00 5/22/94 0:00 + 5/23/94 0:00 5/24/94 0:00 5/25/94 0:00 5/26/94 0:00 5/27/94 0:00 5/28/94 0:00 5/29/94 0:00 5/30/94 0:00 5/31/94 0:00 6/1/94 0:00 6/2/94 0:00 6/3/94 0:00 6/4/94 0:00 Temperature(degrees Celsius) H 1 1 1 1 1 1 1 1— ro o P.-*- . . . . L .0 I H X *^  1 liiirT"1^^ ^^  Use1 y>i x i l 'I II Jrjflh. II Iff 1 H — • i i — " i 1 * 31 era' c • 3 cs 4^ -00 C/J a < B. o 3 31 Er o 3 o 3 " o 3 vO \D LO f » i—p r-r p o" 3 1 9 2 Salinity (ppt) P 5/20/94 0:00 S3. 5. 5/21/94 0:00 CD 5/22/94 0:00 5/23/94 0:00 f 5/24/94 0:00 5/25/94 0:00 5/26/94 0:00 5/27/94 0:00 5/28/94 0:00 5/29/94 0:00 5/30/94 0:00 5/31/94 0:00 6/1/94 0:00 6/2/94 0:00 6/3/94 0:00 6/4/94 0:00 ro —(— 5/7/94 0:00 5/8/94 0:00 5/9/94 0:00 5/10/94 0:00 5/11/94 0:00 5/12/94 0:00 5/13/94 0:00 5/14/94 0:00 5/15/94 0:00 5/16/94 0:00 5/17/94 0:00 5/18/94 0:00 5/19/94 0:00 o ro c n H— r o o -x * HI I II III M • H I -Hh 5 B M I I i ! i +#--m—rw~i hHf-Appendix V: SUSPENDED SEDIMENT RESULTS date station sample # filter weight volume dry weight weight of concentration Average (grams) (ml) (grams) sediment (mg/l) 05/14 1 1 0.09163 480 0.7227 0.63107 1314.729167 05/14 1 2 0.09135 480 0.4534 0.36205 754.2708333 1178.11 05/14 1 3 0.09257 480 0.79593 0.70336 1465.333333 05/14 2 1 0.09323 480 0.1165 0.02327 48.47916667 05/14 2 2 0.09376 480 0.11566 0.0219 45.625 47.0521 05/14 2 3 0.0931 480 05/14 3 1 0.09084 480 0.10682 0.01598 33.29166667 05/14 3 2 0.08965 480 0.10353 0.01388 28.91666667 33.8333 05/14 3 3 0.0925 480 0.11136 0.01886 39.29166667 05/14 4 1 0.09238 360 0.10223 0.00985 27.36111111 05/14 4 2 0.09217 480 0.10157 0.0094 19.58333333 22.8009 05/14 4 3 0.09009 480 0.10039 0.0103 21.45833333 05/14 4a 1 0.09222 480 0.11248 0.02026 42.20833333 05/14 4a 2 0.09308 480 0.12036 0.02728 56.83333333 51.4821 05/14 4a 3 0.09034 420 0.11361 0.02327 55.4047619 05/14 5 1 0.09134 480 0.10395 0.01261 26.27083333 05/14 5 2 0.09108 480 0.10377 0.01269 26.4375 25.1597 05/14 5 3 0.09029 480 0.10122 0.01093 22.77083333 05/14 6 1 0.09264 345 0.10271 0.01007 29.1884058 05/14 6 2 0.09064 480 0.10134 0.0107 22.29166667 24.5975 05/14 6 3 0.08959 480 0.1003 0.01071 22.3125 05/14 11 1 0.0922 480 0.11214 0.01994 41.54166667 05/14 11 2 0.09252 480 0.11125 0.01873 39.02083333 41.8264 05/14 11 3 0.09263 480 0.11419 0.02156 44.91666667 05/14 12 1 0.09213 480 0.10536 0.01323 27.5625 1 05/14 12 2 0.09129 480 0.10218 0.01089 22.6875 22.2222 05/14 12 3 0.09088 480 0.09876 0.00788 16.41666667 05/14 13 1 0.08904 480 0.10451 0.01547 32.22916667 05/14 13 2 0.08988 480 0.10538 0.0155 32.29166667 32.7708 05/14 13 3 0.09073 480 0.10695 0.01622 33.79166667 05/14 14 1 0.08932 480 0.10836 0.01904 39.66666667 05/14 14 2 0.0913 480 0.11456 0.02326 48.45833333 75.1498 05/14 14 3 0.09208 370 0.14289 0.05081 137.3243243 05/18 1 1 0.09202 480 0.12759 0.03557 74.10416667 05/18 1 2 0.09184 480 0.11677 0.02493 51.9375 59.375 05/18 1 3 0.09382 480 0.11882 0.025 52.08333333 05/18 2 1 0.09362 480 0.10641 0.01279 26.64583333 05/18 2 2 0.09357 448 0.10733 0.01376 30.71428571 27.3839 05/18 2 3 0.09336 480 0.10526 0.0119 24.79166667 05/18 3 1 0.09267 480 0.10626 0.01359 28.3125 05/18 3 2 0.09336 480 0.10728 0.01392 29 31.4449 05/18 3 3 0.09312 450 0.10978 0.01666 37.02222222 05/18 4 1 0.08125 480 0.08595 0.0047 9.791666667 05/18 4 2 0.08162 480 0.08616 0.00454 9.458333333 9.83333 05/18 4 3 0.08053 480 0.08545 0.00492 10.25 262 Appendix V; cont'd. 05/18 4a 1 0.09368 353 0.09726 0.00358 10.14164306 05/18 4a 2 0.09326 480 0.09877 0.00551 11.47916667 12.1167 05/18 4a 3 0.0936 480 0.10067 0.00707 14.72916667 05/18 5 1 0.08138 370 0.0844 0.00302 8.162162162 05/18 5 2 0.08159 480 0.08713 0.00554 11.54166667 9.19989 05/18 5 3 0.08194 480 0.08573 0.00379 7.895833333 05/18 6 1 0.09365 480 0.09932 0.00567 11.8125 05/18 6 2 0.09323 480 0.09744 0.00421 8.770833333 9.84028 05/18 6 3 0.09304 480 0.09733 0.00429 8.9375 05/18 11 1 0.08101 480 0.09722 0.01621 33.77083333 05/18 11 2 0.08064 480 0.10111 0.02047 42.64583333 37.123 05/18 11 3 0.08102 420 0.0957 0.01468 34.95238095 05/18 12 1 0.09276 480 0.10496 0.0122 25.41666667 05/18 12 2 0.09316 480 0.10752 0.01436 29.91666667 27.4375 05/18 12 3 0.0917 480 0.10465 0.01295 26.97916667 05/18 13 1 0.0936 480 0.11395 0.02035 42.39583333 05/18 13 2 0.09358 373 0.11617 0.02259 60.56300268 52.6738 05/18 13 3 0.09352 480 0.11995 0.02643 55.0625 05/18 14 1 0.09415 480 0.12772 0.03357 69.9375 05/18 14 2 0.09299 480 0.12745 0.03446 71.79166667 54.5833 05/18 14 3 0.09269 480 0.10326 0.01057 22.02083333 05/19 4a 1 0.0809 480 0.08434 0.00344 7.166666667 05/19 4a 2 0.08092 460 0.08555 0.00463 10.06521739 9.18841 05/19 4a 3 0.08438 480 0.08934 0.00496 10.33333333 05/21 1 1 0.08222 480 0.10274 0.02052 42.75 05/21 1 2 0.08113 480 0.09875 0.01762 36.70833333 38.5486 05/21 1 3 0.08067 480 0.09804 0.01737 36.1875 05/21 2 1 0.08111 480 0.09623 0.01512 31.5 05/21 2 2 0.08132 480 0.09701 0.01569 32.6875 34.4653 05/21 2 3 0.08128 480 0.1001 0.01882 39.20833333 05/21 3 1 0.09308 480 0.10758 0.0145 30.20833333 05/21 3 2 0.09404 480 0.10952 0.01548 32.25 30.5556 05/21 3 3 0.09372 480 0.10774 0.01402 29.20833333 05/21 4 1 0.08471 480 0.09325 0.00854 17.79166667 05/21 4 2 0.0847 480 0.09249 0.00779 16.22916667 16.8056 05/21 4 3 0.08431 480 0.09218 0.00787 16.39583333 05/21 4a 1 0.08466 480 0.09541 0.01075 22.39583333 05/21 4a 2 0.08476 480 0.09265 0.00789 16.4375 20.0833 05/21 4a 3 0.08502 480 0.0953 0.01028 21.41666667 05/21 5 1 0.08444 480 0.09183 0.00739 15.39583333 05/21 5 2 0.08454 480 0.09199 0.00745 15.52083333 15.3333 05/21 5 3 0.08459 480 0.09183 0.00724 15.08333333 05/21 6 1 0.08447 480 0.08847 0.004 8.333333333 05/21 6 2 0.08459 480 0.08828 0.00369 7.6875 8.34722 05/21 6 3 0.08434 480 0.08867 0.00433 9.020833333 05/21 11 1 0.08098 480 0.08511 0.00413 8.604166667 05/21 11 2 0.08104 480 0.08497 0.00393 8.1875 8.20833 05/21 11 3 0.08131 480 0.08507 0.00376 7.833333333 263 Appendix V: cont'd. 05/21 12 1 0.08123 480 0.08529 0.00406 8.458333333 05/21 12 2 0.08173 480 0.086 0.00427 8.895833333 8.86111 05/21 12 3 0.08137 480 0.0858 0.00443 9.229166667 05/21 13 1 0.08197 480 0.09244 0.01047 21.8125 05/21 13 2 0.08095 480 0.08974 0.00879 18.3125 19.2917 05/21 13 3 0.08229 480 0.09081 0.00852 17.75 05/21 14 1 0.09351 480 0.12288 0.02937 61.1875 05/21 14 2 0.09284 480 0.1265 0.03366 70.125 62.782 05/21 14 3 0.08092 418 0.10476 0.02384 57.03349282 05/25 1 1 0.08494 480 0.11621 0.03127 65.14583333 05/25 1 2 0.08485 480 0.11444 0.02959 61.64583333 60.2569 05/25 1 3 0.08472 480 0.11063 0.02591 53.97916667 05/25 2 1 0.08162 480 0.09913 0.01751 36.47916667 05/25 2 2 0.08184 480 0.10294 0.0211 43.95833333 43.1806 05/25 2 3 0.08204 480 0.10561 0.02357 49.10416667 05/25 3 1 0.08269 480 0.09199 0.0093 19.375 05/25 3 2 0.08208 480 0.09584 0.01376 28.66666667 22.3819 05/25 3 3 0.0818 480 0.09097 0.00917 19.10416667 05/25 4 1 0.08153 480 0.08724 0.00571 11.89583333 05/25 4 2 0.08164 480 0.08871 0.00707 14.72916667 13.2569 05/25 4 3 0.08164 480 0.08795 0.00631 13.14583333 05/25 4a 1 0.08122 480 0.09175 0.01053 21.9375 05/25 4a 2 0.08135 480 0.09355 0.0122 25.41666667 22.9514 05/25 4a 3 0.08167 480 0.09199 0.01032 21.5 05/25 5 1 0.08154 480 0.08624 0.0047 9.791666667 05/25 5 2 0.08099 480 0.08538 0.00439 9.145833333 9.63194 05/25 5 3 0.08089 480 0.08567 0.00478 9.958333333 05/25 6 1 0.08176 480 0.08355 0.00179 3.729166667 05/25 6 2 0.08137 480 0.08302 0.00165 3.4375 3.71528 05/25 6 3 0.08136 480 0.08327 0.00191 3.979166667 05/25 11 1 0.08503 480 0.08681 0.00178 3.708333333 \ 05/25 11 2 0.08496 480 0.08669 0.00173 3.604166667 3.40972 05/25 11 3 0.08144 480 0.08284 0.0014 2.916666667 05/25 12 1 0.08472 480 0.08861 0.00389 8.104166667 05/25 12 2 0.08485 480 0.08921 0.00436 9.083333333 8.38194 05/25 12 3 0.08465 480 0.08847 0.00382 7.958333333 05/25 13 1 0.08476 480 0.09318 0.00842 17.54166667 05/25 13 2 0.0849 480 0.09217 0.00727 15.14583333 15.4167 05/25 13 3 0.08477 480 0.09128 0.00651 13.5625 05/25 14 1 0.08427 480 0.10386 0.01959 40.8125 05/25 14 2 0.0844 480 0.10127 0.01687 35.14583333 36.3819 05/25 14 3 0.0845 480 0.10043 0.01593 33.1875 05/27 4a 1 0.08282 480 0.0918 0.00898 18.70833333 05/27 4a 2 0.08334 480 0.09195 0.00861 17.9375 18.8056 05/27 4a 3 0.08158 480 0.09107 0.00949 19.77083333 05/28 1 1 0.08165 480 0.15246 0.07081 147.5208333 05/28 1 2 0.08141 480 0.14702 0.06561 136.6875 151.417 05/28 1 3 0.08135 480 0.16297 0.08162 170.0416667 264 Appendix V; cont'd. 05/28 2 1 0.0827 470 0.10413 0.02143 45.59574468 05/28 2 2 0.0817 480 0.1413 0.0596 124.1666667 103.136 05/28 2 3 0.08192 480 0.14895 0.06703 139.6458333 05/28 3 1 0.08234 480 0.0953 0.01296 27 05/28 3 2 0.08256 426 0.09567 0.01311 30.77464789 28.4225 05/28 3 3 0.08231 355 0.09207 0.00976 27.49295775 05/28 4 1 0.08152 480 0.0918 0.01028 21.41666667 05/28 4 2 0.0817 445 0.09106 0.00936 21.03370787 21.2473 05/28 4 3 0.08114 480 0.09136 0.01022 21.29166667 05/28 4a 1 0.08222 480 0.11419 0.03197 66.60416667 05/28 4a 2 0.08224 480 0.11482 0.03258 67.875 52.3472 05/28 4a 3 0.08224 480 0.09307 0.01083 22.5625 05/28 5 1 0.08176 480 0.08565 0.00389 8.104166667 05/28 5 2 0.08169 480 0.08644 0.00475 9.895833333 9.04167 05/28 5 3 0.08218 480 0.08656 0.00438 9.125 05/28 6 1 0.08096 480 0.08362 0.00266 5.541666667 05/28 6 2 0.08095 480 0.0837 0.00275 5.729166667 5.74306 05/28 6 3 0.08094 480 0.0838 0.00286 5.958333333 05/28 11 1 0.08154 480 0.08745 0.00591 12.3125 05/28 11 2 0.08181 480 0.08785 0.00604 12.58333333 12.4792 05/28 11 3 0.08205 480 0.08807 0.00602 12.54166667 05/28 12 1 0.0822 480 0.08847 0.00627 13.0625 05/28 12 2 0.08286 480 0.08787 0.00501 10.4375 11.5556 05/28 12 3 0.08192 480 0.08728 0.00536 11.16666667 05/28 13 1 0.08214 480 0.10443 0.02229 46.4375 05/28 13 2 0.08148 480 0.09916 0.01768 36.83333333 39.8472 05/28 13 3 0.08144 480 0.09885 0.01741 36.27083333 05/28 14 1 0.08176 480 0.10136 0.0196 40.83333333 05/28 14 2 0.08149 480 0.10012 0.01863 38.8125 38.9861 05/28 14 3 0.08153 480 0.09944 0.01791 37.3125 05/31 1 1 0.08129 480 0.15808 0.07679 159.9791667 05/31 1 2 0.0839 480 0.16334 0.07944 165.5 315.201 05/31 1 3 0.08397 480 0.38163 0.29766 620.125 05/31 2 1 0.08237 480 0.12185 0.03948 82.25 05/31 2 2 0.0827 460 0.13628 0.05358 116.4782609 111.979 05/31 2 3 0.08262 480 0.14848 0.06586 137.2083333 05/31 3 1 0.08273 480 0.09928 0.01655 34.47916667 05/31 3 2 0.08289 480 0.0967 0.01381 28.77083333 31.0977 05/31 3 3 0.08282 463 0.09673 0.01391 30.04319654 05/31 4 1 0.08295 480 0.09177 0.00882 18.375 05/31 4 2 0.08276 480 0.09208 0.00932 19.41666667 18.5903 05/31 4 3 0.08274 480 0.09137 0.00863 17.97916667 05/31 4a 1 0.0833 480 0.09109 0.00779 16.22916667 05/31 4a 2 0.08256 480 0.09016 0.0076 15.83333333 16.3056 05/31 4a 3 0.08267 480 0.09076 0.00809 16.85416667 05/31 5 1 0.08294 480 0.09095 0.00801 16.6875 05/31 5 2 0.08268 480 0.08962 0.00694 14.45833333 15.2917 05/31 5 3 0.0828 480 0.08987 0.00707 14.72916667 265 Appendix V: cont'd. 05/31 6 1 0.0832 480 0.09291 0.00971 20.22916667 05/31 6 2 0.08299 409 0.08987 0.00688 16.82151589 18.1488 05/31 6 3 0.08138 480 0.08973 0.00835 17.39583333 05/31 11 1 0.08165 480 0.08765 0.006 12.5 05/31 11 2 0.08283 480 0.08742 0.00459 9.5625 10.0694 05/31 11 3 0.0828 480 0.08671 0.00391 8.145833333 05/31 12 1 0.08302 480 0.09224 0.00922 19.20833333 05/31 12 2 0.08245 480 0.09171 0.00926 19.29166667 19.25 05/31 12 3 0.08286 480 0.0921 0.00924 19.25 05/31 13 1 0.08443 480 0.10293 0.0185 38.54166667 05/31 13 2 0.08424 480 0.10262 0.01838 38.29166667 39.125 05/31 13 3 0.08467 480 0.10413 0.01946 40.54166667 05/31 14 1 0.08424 480 0.11135 0.02711 56.47916667 05/31 14 2 0.08423 480 0.11165 0.02742 57.125 57.7778 05/31 14 3 0.08457 480 0.11324 0.02867 59.72916667 06/02 4a 1 0.08433 480 0.0939 0.00957 19.9375 06/02 4a 2 0.08435 480 0.09321 0.00886 18.45833333 19.3403 06/02 4a 3 0.08467 480 0.09409 0.00942 19.625 06/07 1 1 0.08284 480 0.11384 0.031 64.58333333 06/07 1 2 0.0831 480 0.11065 0.02755 57.39583333 59.2986 06/07 1 3 0.08277 480 0.10961 0.02684 55.91666667 06/07 2 1 0.08112 480 0.1187 0.03758 78.29166667 06/07 2 2 0.08121 480 0.1259 0.04469 93.10416667 86.3333 06/07 2 3 0.08124 480 0.12329 0.04205 87.60416667 06/07 3 1 0.08334 480 0.09915 0.01581 32.9375 06/07 3 2 0.08337 480 0.10394 0.02057 42.85416667 39.0972 06/07 3 3 0.08344 480 0.10336 0.01992 41.5 06/07 4 1 0.08281 480 0.09041 0.0076 15.83333333 06/07 4 2 0.08283 480 0.09052 0.00769 16.02083333 15.7292 06/07 4 3 0.08272 480 0.09008 0.00736 15.33333333 06/07 4a 1 0.08324 480 0.09992 0.01668 34.75 06/07 4a 2 0.08258 480 0.09961 0.01703 35.47916667 35.1389 06/07 4a 3 0.08241 480 0.0993 0.01689 35.1875 06/07 5 1 0.08306 480 0.08673 0.00367 7.645833333 06/07 5 2 0.08293 480 0.08731 0.00438 9.125 8.03472 06/07 5 3 0.0833 480 0.08682 0.00352 7.333333333 06/07 6 1 0.08325 480 0.08559 0.00234 4.875 06/07 6 2 0.08294 480 0.08533 0.00239 4.979166667 5.1875 06/07 6 3 0.08291 480 0.08565 0.00274 5.708333333 06/07 11 1 0.08317 480 0.08502 0.00185 3.854166667 06/07 11 2 0.08304 480 0.08469 0.00165 3.4375 3.84722 06/07 11 3 0.08129 480 0.08333 0.00204 4.25 06/07 12 1 0.08129 480 0.08563 0.00434 9.041666667 06/07 12 2 0.08144 480 0.08507 0.00363 7.5625 8.47222 06/07 12 3 0.08102 480 0.08525 0.00423 8.8125 06/07 13 1 0.08392 480 0.09449 0.01057 22.02083333 06/07 13 2 0.08343 480 0.09143 0.008 16.66666667 18.2222 06/07 13 3 0.08372 480 0.09139 0.00767 15.97916667 266 Appendix V; cont'd. 06/07 14 1 0.08305 480 0.10265 0.0196 40.83333333 06/07 14 2 0.08294 480 0.10268 0.01974 41.125 41.5139 06/07 14 3 0.08304 480 0.10348 0.02044 42.58333333 06/09 4a 1 0.08096 480 0.08986 0.0089 18.54166667 06/09 4a 2 0.08109 480 0.0899 0.00881 18.35416667 18.6111 06/09 4a 3 0.08101 480 0.0901 0.00909 18.9375 06/11 2 1 0.08145 480 0.20601 0.12456 259.5 06/11 2 2 0.08159 480 0.24038 0.15879 330.8125 399.958 06/11 2 3 0.08139 480 0.37398 0.29259 609.5625 06/11 3 1 0.08138 480 0.13706 0.05568 116 06/11 3 2 0.08147 480 0.16994 0.08847 184.3125 147.05 06/11 3 3 0.08142 465 0.14691 0.06549 140.8387097 06/11 4 1 0.08149 480 0.09969 0.0182 37.91666667 06/11 4 2 0.08139 480 0.10889 0.0275 57.29166667 44.7292 06/11 4 3 0.08125 480 0.09996 0.01871 38.97916667 06/11 4a 1 0.08116 480 0.09587 0.01471 30.64583333 06/11 4a 2 0.08117 480 0.09913 0.01796 37.41666667 28.5556 06/11 4a 3 0.08134 480 0.08979 0.00845 17.60416667 06/11 5 1 0.08101 480 0.10454 0.02353 49.02083333 06/11 5 2 0.08106 480 0.10671 0.02565 53.4375 50.4097 06/11 5 3 0.08118 480 0.10459 0.02341 48.77083333 06/11 6 1 0.08128 480 0.09837 0.01709 35.60416667 06/11 6 2 0.08095 480 0.09845 0.0175 36.45833333 34.5086 06/11 6 3 0.08118 410 0.09408 0.0129 31.46341463 06/11 11 1 0.08145 480 0.09106 0.00961 20.02083333 06/11 11 2 0.0814 480 0.09355 0.01215 25.3125 20.1389 06/11 11 3 0.08127 480 0.08851 0.00724 15.08333333 06/11 12 1 0.08119 480 0.10775 0.02656 55.33333333 06/11 12 2 0.08131 455 0.11057 0.02926 64.30769231 56.1598 06/11 12 3 0.08154 396 0.10088 0.01934 48.83838384 06/11 13 1 0.08144 480 0.20932 0.12788 266.4166667 06/11 13 2 0.08116 480 0.17136 0.0902 187.9166667 189.965 06/11 13 3 0.08132 480 0.13679 0.05547 115.5625 06/11 14 1 0.08148 480 0.19371 0.11223 233.8125 06/11 14 2 0.08152 480 0.22421 0.14269 297.2708333 223.757 06/11 14 3 0.08127 480 0.14856 0.06729 140.1875 06/14 1 1 0.08111 480 0.08494 0.00383 7.979166667 06/14 1 2 0.08112 480 0.08971 0.00859 17.89583333 25.9583 06/14 1 3 0.08086 480 0.10582 0.02496 52 06/14 2 1 0.08097 480 0.0986 0.01763 36.72916667 06/14 2 2 0.08094 480 0.10481 0.02387 49.72916667 53.6319 06/14 2 3 0.08047 480 0.1162 0.03573 74.4375 06/14 3 1 0.08456 480 0.08855 0.00399 8.3125 06/14 3 2 0.08478 480 0.08865 0.00387 8.0625 8.32639 06/14 3 3 0.08472 480 0.08885 0.00413 8.604166667 06/14 4 1 0.08517 480 0.08673 0.00156 3.25 06/14 4 2 0.08458 480 0.08613 0.00155 3.229166667 3.34722 06/14 4 3 0.08493 480 0.08664 0.00171 3.5625 267 Appendix V: cont'd. 06/14 4a 1 0.08469 480 0.09414 0.00945 19.6875 06/14 4a 2 0.08465 480 0.09595 0.0113 23.54166667 21.7431 06/14 4a 3 0.0848 480 0.09536 0.01056 22 06/14 5 1 0.08473 480 0.08646 0.00173 3.604166667 06/14 5 2 0.08499 480 0.08659 0.0016 3.333333333 3.6875 06/14 5 3 0.08501 480 0.08699 0.00198 4.125 06/14 6 1 0.08475 480 0.08597 0.00122 2.541666667 06/14 6 2 0.08253 480 0.08377 0.00124 2.583333333 2.54861 06/14 6 3 0.08243 480 0.08364 0.00121 2.520833333 06/14 11 1 0.0813 480 0.08221 0.00091 1.895833333 06/14 11 2 0.08118 480 0.0824 0.00122 2.541666667 2.47917 06/14 11 3 0.08089 480 0.08233 0.00144 3 06/14 12 1 0.08107 480 0.0828 0.00173 3.604166667 06/14 12 2 0.08469 460 0.08649 0.0018 3.913043478 3.64463 06/14 12 3 0.08489 480 0.08653 0.00164 3.416666667 06/14 13 1 0.08501 480 0.09296 0.00795 16.5625 06/14 13 2 0.08489 480 0.09568 0.01079 22.47916667 28.9931 06/14 13 3 0.08469 480 0.1077 0.02301 47.9375 06/14 14 1 0.08103 480 0.09256 0.01153 24.02083333 06/14 14 2 0.08098 480 0.09153 0.01055 21.97916667 22.5417 06/14 14 3 0.08102 480 0.0914 0.01038 21.625 06/16 4a 1 0.08255 480 0.08708 0.00453 9.4375 06/16 4a 2 0.08251 413 0.08763 0.00512 12.39709443 10.2435 06/16 4a 3 0.08242 480 0.08669 0.00427 8.895833333 06/18 1 1 0.08199 480 0.1721 0.09011 187.7291667 06/18 1 2 0.08182 480 0.18427 0.10245 213.4375 200.583 06/18 2 1 0.08205 480 0.09924 0.01719 35.8125 06/18 2 2 0.08207 480 0.10196 0.01989 41.4375 39.6528 06/18 2 3 0.08212 480 0.10214 0.02002 41.70833333 06/18 3 1 0.08058 457 0.0886 0.00802 17.54923414 06/18 3 2 0.08053 480 0.08841 0.00788 16.41666667 17.0997 06/18 3 3 0.08077 480 0.08909 0.00832 17.33333333 06/18 4 1 0.08065 480 0.08406 0.00341 7.104166667 06/18 4 2 0.08037 480 0.08368 0.00331 6.895833333 7.0625 06/18 4 3 0.08072 480 0.08417 0.00345 7.1875 06/18 4a 1 0.08196 480 0.0881 0.00614 12.79166667 06/18 4a 2 0.0822 480 0.08797 0.00577 12.02083333 13.0347 06/18 4a 3 0.08209 480 0.08895 0.00686 14.29166667 06/18 5 1 0.08216 480 0.08411 0.00195 4.0625 06/18 5 2 0.0807 480 0.08298 0.00228 4.75 4.56457 06/18 5 3 0.08073 463 0.08299 0.00226 4.881209503 06/18 6 1 0.0807 480 0.08262 0.00192 4 06/18 6 2 0.08073 480 0.08264 0.00191 3.979166667 4.09722 06/18 6 3 0.08235 480 0.08442 0.00207 4.3125 06/18 11 1 0.08246 480 0.08411 0.00165 3.4375 06/18 11 2 0.08231 480 0.08428 0.00197 4.104166667 3.59028 06/18 11 3 0.08226 480 0.08381 0.00155 3.229166667 268 Appendix V; cont'd. 06/18 12 1 0.08213 480 0.08401 0.00188 3.916666667 06/18 12 2 0.08206 480 0.08395 0.00189 3.9375 4.11111 06/18 12 3 0.08226 480 0.08441 0.00215 4.479166667 06/18 13 1 0.08228 480 0.08612 0.00384 8 06/18 13 2 0.08215 480 0.08549 0.00334 6.958333333 7.80556 06/18 13 3 0.08181 480 0.08587 0.00406 8.458333333 06/18 14 1 0.08213 480 0.08492 0.00279 5.8125 06/18 14 2 0.08216 480 0.08529 0.00313 6.520833333 5.95833 06/18 14 3 0.08235 480 0.08501 0.00266 5.541666667 06/23 1 1 0.08245 480 0.2474 0.16495 343.6458333 06/23 1 2 0.08233 480 0.24358 0.16125 335.9375 344.104 06/23 1 3 0.08233 480 0.25164 0.16931 352.7291667 06/23 2 1 0.08256 480 0.12182 0.03926 81.79166667 06/23 2 2 0.08255 480 0.13234 0.04979 103.7291667 84.2431 06/23 2 3 0.08278 480 0.11504 0.03226 67.20833333 06/23 3 1 0.08252 480 0.09909 0.01657 34.52083333 06/23 3 2 0.08238 480 0.09557 0.01319 27.47916667 35.876 06/23 3 3 0.08256 398 0.10072 0.01816 45.6281407 06/23 4 1 0.08097 480 0.08865 0.00768 16 06/23 4 2 0.081 480 0.08794 0.00694 14.45833333 17.2014 06/23 4 3 0.08066 480 0.09081 0.01015 21.14583333 06/23 4a 1 0.08055 480 0.08474 0.00419 8.729166667 06/23 4a 2 0.08068 480 0.08528 0.0046 9.583333333 8.52778 06/23 4a 3 0.08087 480 0.08436 0.00349 7.270833333 06/23 5 1 0.08062 480 0.08456 0.00394 8.208333333 06/23 5 2 0.08054 480 0.08356 0.00302 6.291666667 7.45139 06/23 5 3 0.08065 480 0.08442 0.00377 7.854166667 06/23 6 1 0.08071 480 0.08527 0.00456 9.5 06/23 6 2 0.08055 480 0.08392 0.00337 7.020833333 7.77083 06/23 6 3 0.08059 480 0.08385 0.00326 6.791666667 06/23 11 1 0.08082 480 0.0853 0.00448 9.333333333 06/23 11 2 0.08195 465 0.08461 0.00266 5.720430108 7.08042 06/23 11 3 0.08247 480 0.08544 0.00297 6.1875 06/23 12 1 0.08266 480 0.09524 0.01258 26.20833333 06/23 12 2 0.08224 480 0.09826 0.01602 33.375 31.0417 06/23 12 3 0.08242 480 0.09852 0.0161 33.54166667 06/23 13 1 0.08237 480 0.11692 0.03455 71.97916667 06/23 13 2 0.08248 480 0.14417 0.06169 128.5208333 93.1319 06/23 13 3 0.08259 480 0.12046 0.03787 78.89583333 06/23 14 1 0.08255 480 0.11619 0.03364 70.08333333 06/23 14 2 0.08239 480 0.10821 0.02582 53.79166667 55.567 06/23 14 3 0.08247 368 0.09823 0.01576 42.82608696 06/25 1 1 0.08043 480 0.12456 0.04413 91.9375 06/25 1 2 0.08051 480 0.1203 0.03979 82.89583333 87.4167 06/25 2 1 0.08238 480 0.09342 0.01104 23 06/25 2 2 0.08232 480 0.09346 0.01114 23.20833333 24.75 06/25 2 3 0.08029 480 0.09375 0.01346 28.04166667 269 Appendix V: cont'd. 06/25 3 1 0.08063 480 0.08626 0.00563 11.72916667 06/25 3 2 0.08079 480 0.0862 0.00541 11.27083333 11.0903 06/25 3 3 0.08049 480 0.08542 0.00493 10.27083333 06/25 4 1 0.08021 480 0.0824 0.00219 4.5625 06/25 4 2 0.08006 480 0.08214 0.00208 4.333333333 4.53472 06/25 4 3 0.08025 480 0.08251 0.00226 4.708333333 06/25 4a 1 0.08037 480 0.08703 0.00666 13.875 06/25 4a 2 0.08048 480 0.08624 0.00576 12 12.2986 06/25 4a 3 0.08037 480 0.08566 0.00529 11.02083333 06/25 5 1 0.08125 480 0.08351 0.00226 4.708333333 06/25 5 2 0.08095 480 0.08329 0.00234 4.875 4.78472 06/25 5 3 0.08083 480 0.08312 0.00229 4.770833333 06/25 6 1 0.0809 480 0.08244 0.00154 3.208333333 06/25 6 2 0.08099 480 0.08274 0.00175 3.645833333 3.40972 06/25 6 3 0.0811 480 0.08272 0.00162 3.375 06/25 11 1 0.08043 480 0.08259 0.00216 4.5 06/25 11 2 0.08036 480 0.0827 0.00234 4.875 5.03472 06/25 11 3 0.0801 480 0.08285 0.00275 5.729166667 06/25 12 1 0.08283 480 0.08578 0.00295 6.145833333 06/25 12 2 0.0827 480 0.08556 0.00286 5.958333333 5.94444 06/25 12 3 0.08251 480 0.08526 0.00275 5.729166667 06/25 13 1 0.08247 480 0.08686 0.00439 9.145833333 06/25 13 2 0.0825 480 0.08791 0.00541 11.27083333 10.0556 06/25 13 3 0.08253 480 0.08721 0.00468 9.75 06/25 14 1 0.08067 480 0.08933 0.00866 18.04166667 06/25 14 2 0.08092 480 0.08931 0.00839 17.47916667 19.1667 06/25 14 3 0.08067 480 0.09122 0.01055 21.97916667 06/28 1 1 0.08042 480 0.22227 0.14185 295.5208333 06/28 1 2 0.08069 480 0.22975 0.14906 310.5416667 294.361 06/28 1 3 0.08137 480 0.21434 0.13297 277.0208333 06/28 2 1 0.08074 480 0.09572 0.01498 31.20833333 06/28 2 2 0.08061 480 0.09108 0.01047 21.8125 28.1944 06/28 2 3 0.08076 480 0.09591 0.01515 31.5625 06/28 3 1 0.0807 464 0.08785 0.00715 15.40948276 06/28 3 2 0.08064 480 0.08641 0.00577 12.02083333 13.3865 06/28 3 3 0.08077 480 0.08688 0.00611 12.72916667 06/28 4 1 0.08049 480 0.08389 0.0034 7.083333333 06/28 4 2 0.08067 480 0.08401 0.00334 6.958333333 7.01389 06/28 4 3 0.08058 480 0.08394 0.00336 7 06/28 4a 1 0.08053 480 0.08644 0.00591 12.3125 06/28 4a 2 0.08042 480 0.0963 0.01588 33.08333333 19.0694 06/28 4a 3 0.08088 480 0.08655 0.00567 11.8125 06/28 5 1 0.08047 480 0.08236 0.00189 3.9375 06/28 5 2 0.08073 480 0.0825 0.00177 3.6875 3.86111 06/28 5 3 0.08024 480 0.08214 0.0019 3.958333333 06/28 6 1 0.08066 480 0.08198 0.00132 2.75 06/28 6 2 0.0806 480 0.08167 0.00107 2.229166667 2.63889 06/28 6 3 0.08064 480 0.08205 0.00141 2.9375 2 7 0 Appendix V: cont'd. 06/28 11 1 0.0814 480 0.08295 0.00155 3.229166667 06/28 11 2 0.08129 480 0.08366 0.00237 4.9375 4.19444 06/28 11 3 0.08157 480 0.08369 0.00212 4.416666667 06/28 12 1 0.08096 480 0.08466 0.0037 7.708333333 06/28 12 2 0.08081 480 0.08448 0.00367 7.645833333 7.70139 06/28 12 3 0.08066 480 0.08438 0.00372 7.75 06/28 13 1 0.08087 480 0.08991 0.00904 18.83333333 06/28 13 2 0.08148 480 0.09415 0.01267 26.39583333 20.8681 06/28 13 3 0.08124 480 0.08958 0.00834 17.375 06/28 14 1 0.081 480 0.09362 0.01262 26.29166667 06/28 14 2 0.08094 480 0.09318 0.01224 25.5 26.1319 06/28 14 3 0.08085 480 0.09362 0.01277 26.60416667 271 Appendix VI: RESULTS AND STATISTICAL ANALYSES OF GRAIN SIZE MEASUREMENTS VI-1. STATISTICAL ANALYSES Mean grain size is a function of (1) the size range of available materials and (2) the amount of energy imparted to the sediment which depends on current velocity or turbulence of the transporting medium. The grain size scale was devised by Udden (1898) and is based on a constant ratio of 2 between successive size classes. The names of the class intervals were proposed by Wentworth (1922) and modern grain size data is nearly always stated in terms of phi units <p = -log2S (where S is size in millimetres), a logarithmic transformation of the Wentworth scale devised by Krumbein (1934). Grain size parameters are calculated generally by either graphical techniques using percentiles read from a cumulative curve (Folk and Ward, 1957) or by the method of moments using grouped size weight-frequency data (Friedman, 1967). The method of moments is a computational (not graphical) method of obtaining values, in which every grain in the sediment affects the measure. Thus it probably gives a truer picture than the graphic methods, which rely on only a few selected percentage lines (Folk, 1968). Swan et al. (1978, 1979) found that graphical measures were relatively insensitive to significant deviations from normality in grain-size distributions and therefore classification schemes of sediment types should make use of graphic parameters only if the range in values of statistical parameters is sufficiently large such that the limitations of the graphic technique do not significantly affect the classification units. Although the grouping of grain size data into class intervals permits a reduction in the amount of data to be examined there is obviously information lost in the grouping procedure. The 272 authors also found that the accuracy of grouped moment measures improves as the class interval sizes decrease and that the errors due to grouping grain-size data into size classes are small and can be ignored for most sediment types. They concluded that the use of grouped moment measures will lead to environmental interpretations consistent with the actual characteristics of the size weight-frequency distributions of the samples and therefore the method of moments has been used to describe the statistical parameters of sediments on Sturgeon Bank. The first moment describes the mean and is defined as: _ n *<(> = ^2 fi m i c > 1=1 The second moment describes the standard deviation or sorting and is defined as: n _ s + =[g/, (M i + -j : + ) 2 ] V i where /, = fraction of the total weight in each class interval; mi4> = the midpoint of each class interval in phi units; and = 1 + (c\>f - cpc) where i\>f is the midpoint of the finest mode and cbc 2(b is the midpoint of the coarsest mode. Examination of the results shows that the moment method of analysis gives values which are 0.08cj) higher (coarser) in grain size and 0.17(j) higher (poorer sorted) in standard deviation on average than the values calculated using the graphical method. 273 sorting Pettijohn well | moderate | poor | well | poor 1 moderate | well | well | moderate | moderate | moderate | poor | poor | moderate | well | moderate | very poor | very poor | very poor | very poor | very poor | very poor | very poor | very poor | poor | very poor | very poor | moderate | moderate | very poor | very poor | moderate | | moderate | I poor | I poor | std. dev phi (Folk) 0.31743 | 0.50432 | 1.6659 | 0.26007 | 1.16174 I 0.45495 | 0.31148 | 0.3067 | 0.49902 | 0.61652 | 0.48133 | 1.31221 | 1.16858 | 0.34779 | 0.25052 | 0.33421 | 2.29171 | 2.1866 | 2.59092 | 2.47042 | 2.51395 | 2.29761 2.33848 2.02859 1.90212 2.34389 1.966425 0.47715 0.49142 2.20417 2.183755 | 0.45175 | 0.46478 | 0.62199 | 1.69385 std. dev. moment 0.50197 | 0.66968 | 1.93456 | 0.38764 | 1.42569 | 0.62834 | 0.44292 | 0.44331 | 0.59993 | 0.74705 | 0.61117 | 1.87893 | 1.7306 | 0.50796 | 0.35434 | 0.56999 | 2.4213 | 2.30315 | 2.65323 | 2.57768 | 2.58032 | 2.3808 | 2.49202 2.20817 1.88574 2.54181 2.22606 fO.65324 fO.57796 2.32068 | 2.29048 I 0.60974 | 0.61246 M. 17826 | 1.89391 silt/mud 1.0086 | -0.9066 | 0.9455 | - ---0.6113 | 0.7165 | -0.989 | -0.7558 | 0.7398 | 0.671 | 0.6816 | 0.689 | 0.7606 0.6922 0.7072 0.7713 0.6545 0.6685 --0.794 0.7849 -| 0.7507 | 0.8456 clay/silt 0.103 | 0.0577 | 0.6359 | 0.3958 | 0.3231 | 0.3517 | 0.4904 | 0.4668 j 0.4514 0.3147 0.4447 0.4136 0.2966 0.5274 0.4959 0.2594 0.274 I 0.332 | 0.1828 sand/mud 84.77 | 39.16 | 1.43 | 130.78 | d 52.51 | 122.76 | 115.66 | 53.84 | 30.02 | 16.63 | 7.43 | 5.07 | 50.22 | 109.53 | 25.5 | 0.88 | 1.16 | 0.74 | 1.09 j 0.89 | 1.07 1.58 2.39 0.03 co 2.89 26.82 74.59 0.63 0.78 23.09 35.64 13.5 | 1.38 % mud 1.16 | 2.49 | 41.22 | 0.76 | 91.31 | 1.87 | 0.81 | 0.86 | 1.82 | 3.22 | 5.67 | 11.86 | 16.47 | 1.95 | 0.91 | 3.77 | 53.28 | 46.35 | 57.53 | 47.77 | 52.83 | 48.25 | 38.79 29.47 96.75 43.42 25.73 3.59 1.32 61.27 56.16 4.15 2.73 O) CO | 41.98 % clay 3.85 | 4.98 | 4.61 | 4.67 | 13.01 | 12.06 | 18.93 | 15.2 | 16.43 j 11.55 11.94 8.62 22.13 14.99 8.53 12.62 12.08 1.72 6.49 % silt 1.17 2.49 | 37.37 | 0.76 | 86.33 | 1.87 | 0.81 | 0.86 | 1.82 | 3.22 | 5.67 | 7.25 | 11.8 | 1.95 O) d 3.77 | 40.27 | 34.29 | 38.6 | 32.56 | 36.4 | 36.7 | 26.85 | 20.84 | 74.62 | 28.42 | 17.2 3.59 1.32 48.65 44.08 4.15 2.73 5.18 35.5 % sand 98.83 | 97.51 | 58.78 | 99.24 | 8.69 | 98.13 | 99.19 | 99.14 | 98.18 | 96.78 | 94.33 | 88.14 | 83.53 | 98.05 | 99.1 | 96.23 | 46.72 | 53.65 | 42.47 | 52.23 | 47.17 | 51.75 j 61.21 | 70.53 3.25 56.58 74.27 96.41 98.68 38.73 43.84 95.85 97.27 93.1 58.02 Wentworth Size class medium sand | fine sand | very fine sand | medium sand | medium silt | medium sand | medium sand | medium sand | fine sand | fine sand | fine sand | very fine sand | very fine sand | fine sand | fine sand fine sand | coarse silt coarse silt | medium silt coarse silt | medium silt | coarse silt | coarse silt very fine sand | fine silt coarse silt very fine sand | fine sand | fine sand medium silt | coarse silt | fine sand fine sand very fine sand coarse silt Grain size Folk (phi) 1.67471 | 1.96372 | 3.55775 | 1.88997 | 5.08571 I 1.78922 | 1.69004 | 1.63638 | 2.22107 | 2.32548J 2.81981 | 2.66074 | 3.27142 I 2.69664 | 2.36028 I 2.50782 | 4.87447 I 4.62927 | 5.25894 | 4.71002 | 4.94467 | 4.5244 | 4.27605 4.01547 | 6.71932 I 4.72382 I 3.877005J 2.33639 | 2.11661 I 5.00321 I 4.84165J 2.67757 j 2.33615 2.90576 I 4.12368 Grain size moment (phi) 1.72521 I 2.02121 I 3.79885 I 1.92928 I 5.23265 I 1.86152 I 1.725 I 1.67072 I 2.26421 I 2.36425 I 2.89102 I 3.04437 I 3.56792 I 2.706085 I 2.38174 I 2.5787 I 4.95664 I 4.75236 I 5.31535 I 4.85412 I 5.03542 I 4.64287 I 4.3768 I 3.98674 I 6.74339 I 4.89037 I 3.899885 2.41946 2.15317 5.14016 4.9445 2.73779 2.39052 3.05861 | 4.33347 Station < < CM < CO < < < CO < tv < oo < O) < o < < CM < CO < rr < io < CD < iv < oo < m O O) Q a> Ul O) 20A 21A 22A 23A 24A I 25A 26A 27A 28A 29A 30A | 31A 274 sorting Pettijohn moderate | moderate | well | moderate | poor | very poor | moderate | very poor | I well | | moderate | moderate | | moderate | | well | | moderate | | moderate | | well | | well | | well | | moderate | | well | | well | | well | | very well | | well | | well | I poor | | very poor | | very poor | I Poor | | moderate | | well | | well | | moderate | | very poor | | very poor | td. dev (Foil phi 0.49356 | 0.43657 | 0.41014 | 0.58904 | 0.63034 | 2.00852 | | 0.45659 | | 2.18732 | | 0.22404 | | 0.32829 | | 0.36403 | | 0.346475 | | 0.34087 | | 0.52476 | | 0.44068 | | 0.32746 | | 0.22598 | | 0.23644 | | 0.34088 | | 0.28383 | | 0.28767 | | 0.33055 | | 0.29712 | | 0.28427 | | 0.33738 | 1.89591 | 2.08645 | 2.7215 | 0.74639 | 0.47274 | 0.27638 | 0.32752 | 0.47505 | 2.66127 05 35 CM std. dev. moment 0.61998 | 0.50634 | 0.48829 | [ 0.71701 | | 1.33326 | | 2.21418 | | 0.55626 | | 2.19007 | | 0.46608 | | 0.505 | | 0.61589 | | 0.54488 | | 0.37454 | | 0.65558 | | 0.63663 | | 0.48901 | | 0.39877 | | 0.3863 | | 0.549 | | 0.38547 | | 0.42253 | | 0.45899 | | 0.30909 | | 0.41248 | | 0.45265 | | 1.95905 | 2.11517 | 2.76605 | 1.28874 | 0.65205 | 0.44547 | 0.44261 | 0.97888 | 2.58217 CM CM CO CM silt/mud - -0.6934 | | 0.7149 | | 0.7715 | - - - T— - - - - - - -| 0.8303 | 0.7287 | 0.612 | 0.6248 T— | 0.8137 | 0.6677 CO o LO r>-CD clay/silt 0.4422 | 0.3984 | | 0.296 | | 0.2043 | | 0.3723 | 0.6341 | 0.6005 | 0.2289 | 0.4978 CM CO CO 6 sand/mud 14.41 | 97.6 | CO o 18.57 | 10.44 | 1.67 | | 58.89 | [ 0.11 | | 56.46 | | 36.91 | | 27.68 | | 37.76 | | 341.07 | | 29.31 | | 26.06 | | 45.23 | CM CD | 86.49 | | 45.89 | | 106.65 | | 76.31 | | 178.51 | o | 92.71 | | 125.91 | I 0.12 | | 0.04 | I 0.61 I | 15.97 | | 49.37 | | 110.14 | 05 f-| 23.52 | 0.29 ^ -CM CD % mud 6.49 | ( 1.01 | | 0.96 | I 5.11 | I 8.74 | I 37.5 | I 1-67 | | 89.72 | 1 1-74 | I 2.64 | | 3.49 | | 2.58 | | 0.29 | CO CO | 3.69 | I 2.16 | | 1.59 | 1 1-14 | I 2.13 | | 0.93 | I 1-29 I | 0.56 | o I 1-07 | | 0.79 | | 89.06 | | 96.14 | | 62.16 | | 5.89 | | 1.99 | 05 CD I 1-25 j | 4.08 j | 77.69 | CO CO CD CO % clay | 2.68 | | 10.68 | | 20.49 | I 15.11 | 26.08 | 24.12 I 2.21 I 0.76 | 25.82 CM o CD CM % silt I 6.49 | I 1-01 I | 0.96 | I 5.11 | | 6.06 | | 26.81 | I 1-67 | | 69.22 | I 1-74 | I 2.64 | | 3.49 | | 2.58 | | 0.29 | CO CO | 3.69 | I 2.16 | | 1.59 | I 1-14 | I 2.13 | | 0.93 | I 1-29 | | 0.56 | I 1-07 | | 0.79 | | 73.95 j | 70.06 j | 38.04 | | 3.68 | | 1.99 05 CD I 1-25 | 3.32 | 51.87 CO CD CO % sand 93.51 | 98.99 | I 99.04 | 94.89 | | 91.26 | I 62.5 | | 98.33 | | 10.29 | | 98.26 | | 97.36 | | 96.51 | | 97.42 | | 99.71 | | 96.7 | | 96.31 | | 97.84 | | 98.41 | | 98.86 | | 97.87 | | 99.07 | | 98.71 | | 99.44 | o o | 98.93 | | 99.21 | | 10.94 | | 3.86 | | 37.84 | | 94.11 | | 98.01 | | 99.1 | | 98.75 | 95.92 | 22.31 CO 05 Wentworth Size class fine sand ] fine sand | fine sand | | fine sand | very fine sand | coarse silt | | fine sand | fine silt | | medium sand | fine sand | | fine sand | | fine sand | | medium sand | | fine sand | | fine sand | | fine sand | | fine sand | | fine sand | fine sand | | fine sand | fine sand | | medium sand | medium sand | | fine sand | | medium sand | fine silt | | fine silt | | medium silt | fine sand | | medium sand | | medium sand | fine sand | fine sand | fine silt | | tine silt | Grain size Folk (phi) 2.88624 | 2.24806 | 2.15316 | 2.42158 | | 2.96786 | | 4.38316 | | 2.31729 | | 6.23336 | | 1.91935 | | 2.51833 | | 2.0948 | | 2.318255 | | 1.94568 | | 2.33533 | | 2.28763 | | 2.3599 | | 2.43495 | | 2.09511 | | 1.97105 | | 2.0967 | | 2.09862 | | 1.62085 | | 1.72195 | | 2.09097 | | 1.73051 | | 6.19805 | | 6.95904 | | 5.78823 | | 2.60165 | | 1.71232 | | 1.53103 | | 2.30804 | | 2.18385 | | 6.24386 CO LO CM CD CO Grain size moment (phi) 2.97692 | 2.27421 | 2.17117 | 2.52037 | | 3.21369 | | 4.44024 | I 2.37118 | j 6.27506 | | 1.96256 | | 2.57723 | | 2.18812 | | 2.35456 | | 1.96998 | | 2.40691 | | 2.37006 | | 2.40637 | | 2.44876 | | 2.12872 | | 2.03452 | | 2.11617 | | 2.12678 | | 1.64487 | | 1.73357 | | 2.1215 | | 1.75728 | | 6.18689 | | 7.00761 | | 5.83718 | | 2.80507 | | 1.76047 | | 1.55771 | | 2.33224 | | 2.33846 | | 6.3928 | LO CO LO CO CM CO Station I 32A I I 33A I 34A I 35A I I 36A I I 38A I I 39A I I 40A I I 41A I I 42A I I 43A I I 44A I I 45A I I 46A I I 47A I I 48A I I 49A I I 50A I I 51A I I 52A I I 53A I I 54A I I 55A I I 56A I I 57A I CO I S2 I I S3 I S4 I S5 I I S6 I I S11 I I S12 I I S13 I CO 275 Appendix VII: SEDIMENT GEOCHEMISTRY - ANALYTICAL DESCRIPTION VII-1. MAJOR ELEMENT ANALYSIS (Al, Si, Ti, K, Na, Ca, Fe, Mg, P) Major element compositions were determined on fused glass discs using X-ray fluorescence following Norrish and Hutton (1969). Ground sediment weighing 0.400 g was added to a preweighed Pt-Au crucible. Added to the crucible was 3.600 g of Spectroflux 105® (47.03% Li2B407 (lithium tetraborate); 36.63% LiC03 (lithium carbonate); 16.34% La203 (lanthanum oxide)) and the mixture was heated in an electric muffle furnace at 1100°C for 30 minutes. Lithium tetraborate and lithium carbonate reduce the melting temperature of the flux to 700°C while lanthanum oxide acts as a heavy absorber increasing the mass absorption of the samples which decreases the matrix absorption contrasts between samples. The crucibles were cooled to room temperature in an aluminum cooling block and then reweighed. The sample:lanthanum ratio must be kept constant in order to maintain consistent analyses. The weight of the Spectroflux 105® is included in the sample weight and therefore the weight lost when the sample and crucible are heated must be made up to maintain a constant sample:lanthanum ratio. Spectroflux 100® was added to make up the weight lost on fusion due to the oxidation of organic matter and the volatization of H20, CaC03 and other components. Spectroflux 100® only contains Li2B407 which, upon addition, maintains the sample:La ratio. The sample was reheated over a Meeker burner in a fume hood until melted and then poured into an aluminum mold on a hot plate maintained at 400°C. A brass plunger lowered onto molten sample flattened it into a disc. The disc was allowed to cool slowly, trimmed and stored in a clean plastic bag until further analysis. Results of major element analyses on sediments from Sturgeon Bank are given in VII-6. 276 VII-2. MINOR ELEMENT ANALYSIS (Rb, Ba, Sr, Co, Cr, Ni, V, Y, Mn, Cu, Zn, Pb, Zr) Minor element compositions were determined on pressed powder pellets using X-ray fluorescence. Four grams of ground sediment were mixed with one drop of PVA (polyvinyl alcohol -CH2CH(OH)-) binder solution and the sample placed in a stainless steel die and formed into a rigid, borate-backed pellet in a hydraulic press at 10 tons of pressure for one minute. The pellets were labelled and stored face-down in a tissue-lined box until further analysis. Results of minor element analyses on sediments from Sturgeon Bank are given in VII-7. VII-3. X-RAY FLUORESCENCE SPECTROMETRY Major and minor element compositions were determined on the fused glass discs and pressed powder pellets using an automated Philips PW 1400 X-ray fluorescence spectrometer. A Rh-target X-ray tube was used for excitation and the spectrometer was controlled by a DEC PDT®-11 microcomputer which calculated the elemental concentrations from the X-ray counts. The instrument settings are listed in VH.-8. International geochemical rock standards were placed within the XRF sample runs and were used to monitor the accuracy of results. VH-9 lists the standards used and compares the measured values to those referenced in Abbey (1980). Analytical precision is represented by the standard deviation (2o; 95% confidence interval) of a set of replicate samples and the results of standard deviation measurements for all elements are shown in VII-10. Analytical precision was determined by dividing two unique sediment samples into six replicate sub-samples, analyzing them for major and minor element composition, averaging the standard deviations measured for both sets of replicate samples and then displaying them in terms of relative standard deviation (i.e. as a percentage of the mean). 277 VH-4. TOTAL CARBON AND NITROGEN ANALYSIS Total carbon and nitrogen were determined by gas chromatography/thermal conductivity on a Carlo-Erba CNS analyzer (model NA-1500). Twenty five to thirty five mg of ground sediment were weighed into tin cups using a Mettler precision balance. The sample was introduced into a combustion column reactor by means of an autosampler and flash combusted at 1050°C in an enriched atmosphere of ultra-pure quality oxygen and helium. The sample and tin container melted at this temperature and the combustion products (C02, NOx and F4 O) were oxidized by passing through a column of Cr203. The products were then swept through the combustion reactor into a reduction reactor where nitrogen oxides were reduced to N2 and excess oxygen was removed as the gases passed over copper heated to 650°C. C02, N2 and H20 were separated on a chromatographic column and then measured by a thermal conductivity detector. The integration of the gas peaks was through the Carlo-Erba "Eager" program that recorded the results on a digital printout Technical specifications of the CNS analyzer give detection limits of 10 ppm with better than 0.1% absolute value reproducibility. Five acetanilide (CH3CONHC6H5; 71.09% C and 10.36% N by weight) samples were placed within the sample run and used to monitor the accuracy of results. Three other standards, PACS-1, MESS-1 and BCSS-1 and a blank cup were analyzed twice each during a sample run of 38 samples. The mean of the two blanks was subtracted from the total counts for each analysis and the constants, K,^,, and K^g,,,, were calculated using the following formulae: Kcarbon = % C in standard Areac of standard (counts) 278 71.09 Total counts (C) - blank The mean of the constants for the five standards was taken to be K^,,,, for the run, and the total carbon of the sample was then calculated by %C = Kc Area of sample (counts)Avt. of sample Total nitrogen was calculated using 10.36% N in the standard. From the equations K,.^,, = 1.813 + 0.0010302x (r = 0.99855) and K ^ , , = 2.2118 + 0.0029021x (r = 0.99974). Analytical precision was determined by dividing two unique samples into six replicate sub-samples and analyzing them for total carbon and nitrogen content. The precision was measured as the average of twice the standard deviation (2o) for these analyses, reported as a percentage of the mean and was determined to be ± 4.84% for carbon and ± 9.06% for nitrogen (VTI-11). VII-5. INORGANIC CARBON ANALYSIS Carbonate carbon (inorganic carbon) was determined by coulometry. Approximately 50 to 100 mg of ground sediment were placed in a glass test tube and then connected to a Coulometrics Inc. C02 coulometer and carbonate carbon apparatus. Two coulometers, models 5010 and 5011 (coulometers 1 (blue) and 2 (grey), respectively), and two carbonate carbon apparatus, models 5030 and 5130 (coulometers 1 (blue) and 2 (grey), respectively), were used in the analyses. The tube was flushed with C02-free air for two minutes to ensure no CQ contamination from the atmosphere. After two minutes, while the air continued to flush, 2 ml of 10% HCl were added to the test tube containing the sample and the COz gas evolved was carried to a titration cell. The cell was filled with a solution of ethanolamine and a colorimetric indicator which quantitatively absorbed the COz. 279 The C02 reaction with the ethanolamine forms a strong titratable acid, i.e. C02 + HO-CH2-CH2-NH2 - - -> HO-CH2-CH2-NH-COOH (ethanolamine + colorometric indicator) (titratable acid) This reaction causes the blue indicator color to fade, which then causes the transmittance of a light beam through the solution to increase. As the percent transmission increases, a titration current switches on automatically and OH" ions are generated by reducing HzO at a silver electrode, i.e. Ag° ---> Ag+ + e" H20 + e" ---> V2H2 + OH-The OH" neutralizes the acid, causing the solution to return to its original color, at which point the current is automatically switched off, i.e. HO-CH2-CH2-NH-COOH + OH" - - -> HO-CH2-CH2-NOO- + H20 The total amount of current used for the titration is integrated and the result is displayed as pg C. This figure is then converted to % carbonate carbon using the formula: % Cc a r t ) = u^ o 2-ugC b l a n k X100 sample weight Blank samples were run at the beginning of each sample run and ranged in value from 5.0 to 11.03 pg C. Detection limits for both coulometers are 0.01 pg C. Calcium carbonate (12% C) samples were run at the beginning of each sample run to monitor the accuracy of the results. Measured standard values gave mean values of 11.29, 11.69, and 10.94% carbonate carbon for coulometer (1) on the three days of analyses, respectively and 11.89 and 11.99% carbonate carbon for coulometer (2) on the two days of analyses, respectively which 280 corresponds to an accuracy of 6%, 2.6%, and 8.8% for coulometer (1) on the three days of analyses, respectively and 0.9% and 0.08% for coulometer (2) on the two days of analyses, respectively. The precision is measured as the average of twice the standard deviation (2o) for these analyses and reported as a percentage of the mean. The precision measurements for inorganic carbon was ± 28.63% on coulometer (1) and ± 13.10% on coulometer (2) (VjT-12). Random samples were also selected and run on both coulometers for comparison. Upon determination of both % total carbon and % total inorganic carbon, % organic carbon was calculated by difference. Results of carbon and nitrogen analyses are shown in VII-13. 281 VII-6: MAJOR ELEMENT RESULTS Sample # Al (wt. %) Si (wt. %) Ti (wt. %) K (wt. %) Na (wt. %) Ca (wt. %) Fe (wt. %) M g (wt. %) P (wt. %) IB 5.74494 36.8463 0.258 0.76041 1.13526 1.66595 2.681 0.92259 0.05232 2B 5.49102 36.72488 0.258 0.79236 1.01654 1.52295 2.625 0.89847 0.05232 3B 5.90893 34.24511 0.426 0.92016 1.04622 2.002 3.297 1.39293 0.07412 4B 5.48044 37.08447 0.264 0.77958 0.96089 1.5301 2.31 0.98892 0.04796 5B 6.62837 31.62057 0.51 1.0224 1.09445 2.33805 3.619 1.64619 0.0872 6B 5.61798 36.82295 0.264 0.76041 1.30963 1.6016 2.772 1.07334 0.05232 7B 5.60211 34.82886 0.3 0.74124 1.22059 1.98055 2.933 1.12158 0.05668 8B 5.58095 36.06641 0.258 0.73485 1.08332 1.6159 2.611 0.9648 0.05668 9B 5.49631 35.97768 0.39 0.77958 1.08703 1.83755 3.073 1.10349 0.05232 10B 5.49102 36.32793 0.294 0.79236 0.95718 1.59445 2.73 1.12158 0.05232 1 IB 5.43812 34.92226 0.45 0.83709 0.95347 1.859 3.276 1.22409 0.06976 12B 5.48044 35.28185 0.348 0.8307 1.00541 1.76605 3.01 1.09143 0.0654 13B 5.6603 34.41323 0.426 0.87543 1.01654 1.8876 3.248 1.24821 0.06104 14B 5.40109 34.62338 0.576 0.78597 0.94234 2.10925 3.829 1.27836 0.06104 15B 5.38522 36.36529 0.264 0.75402 1.02025 1.63735 2.674 1.06128 0.05232 16B 5.17891 36.07108 0.3 0.86265 1.01654 1.4729 2.716 0.95274 0.05232 17B 6.4009 31.89143 0.516 1.03518 0.94976 2.06635 3.857 1.55574 0.0872 18B 6.30568 32.31173 0.45 1.00962 1.05735 1.9162 3.64 1.50147 0.08284 19A 6.1893 31.32169 0.438 1.04796 1.04251 1.82325 3.675 1.39293 0.08284 19B 6.63366 32.83477 0.45 1.06713 1.03138 1.80895 3.689 1.52559 0.0872 19C 6.5067 32.60594 0.438 1.02879 0.99799 1.8447 3.738 1.49544 0.09156 19D 6.38503 32.92817 0.438 1.03518 0.92379 1.80895 3.675 1.5075 0.0872 19E 5.7661 32.42381 0.414 0.97767 0.90524 1.78035 3.388 1.29042 0.06976 20B 5.42225 32.61528 0.384 0.92655 0.92379 1.75175 2.856 1.1457 0.0654 21B 7.22085 29.70587 0.492 1.2141 0.99428 1.85185 4.256 1.68237 0.10028 22B 5.85603 31.59722 0.462 0.93933 0.90153 1.9162 3.612 1.36881 0.07848 23B 6.00944 33.6707 0.51 0.92016 1.0388 2.00915 3.738 1.47132 0.06976 24B 5.29 35.35657 0.36 0.79875 1.10558 1.716 2.975 0.97083 0.05232 25B 5.42225 35.77687 0.33 0.77958 1.00541 1.7589 2.828 1.04922 0.05232 26B 6.22633 31.48047 0.486 1.03518 0.86814 2.002 3.745 1.48338 0.07848 27B 6.37445 31.97082 0.54 0.9585 0.94234 2.18075 3.962 1.56177 0.07848 28B 5.3958 34.56734 0.594 0.74124 1.02767 2.03775 4.123 1.31454 0.06104 29B 5.30587 34.90825 0.42 0.75402 1.06477 1.86615 3.248 1.16379 0.05668 30B 5.34819 33.84349 0.558 0.77958 0.99428 2.13785 3.696 1.3266 0.06976 31B 6.02531 33.23172 0.552 0.87543 1.02396 2.2308 3.815 1.47735 0.0872 32B 5.68675 35.73951 0.54 0.79236 1.04622 2.12355 3.717 1.41705 0.0654 33B 5.07311 34.57201 0.36 0.77958 1.0388 1.9162 2.975 1.12158 0.06104 34B 5.24239 34.76348 0.366 0.75402 1.0017 1.85185 3.094 1.06731 0.05668 35B 5.54392 35.68347 0.36 0.79236 0.96831 1.7732 3.017 1.16982 0.05668 36B 5.40109 33.68471 0.648 0.76041 1.02025 2.2165 4.158 1.31454 0.06976 38B 5.96712 32.69 0.576 0.90099 1.10558 2.13785 4.039 1.56177 0.08284 39B 5.29529 35.3052 0.378 0.77319 1.07961 1.80895 3.227 1.09746 0.05668 40B 6.90874 30.1682 0.51 1.13103 1.09074 2.0449 4.221 1.70649 0.09156 41B 5.21065 36.31392 0.27 0.79875 1.04251 1.4872 2.639 0.85626 0.05232 42B 5.43283 35.31921 0.456 0.77319 0.94605 1.93765 3.458 1.21806 0.06104 43B 5.44341 35.91697 0.3 0.7668 1.03138 1.6731 3.01 1.11555 0.0654 44B 5.24768 35.26317 0.384 0.81153 1.09074 1.8018 3.045 1.12761 0.05232 45B 5.31116 34.40389 0.408 0.73485 1.05364 1.93765 3.255 1.18188 0.04796 46B 5.39051 34.98297 0.39 0.79875 0.99428 1.79465 3.024 1.15173 0.04796 47B 5.64443 33.96491 0.378 0.91377 0.96089 1.69455 3.08 1.05525 0.05668 48B 5.27942 36.55676 0.294 0.79875 1.09074 1.5587 2.485 1.03716 0.04796 49B 4.98847 35.58073 0.288 0.85626 1.16494 1.63735 2.422 1.06731 0.0436 50B 5.25297 36.15047 0.318 0.7668 1.05364 1.79465 2.723 1.13364 0.0436 51B 5.35348 36.1925 0.27 0.77319 1.20204 1.5444 2.499 0.95877 0.0436 52B 5.24768 36.01971 0.282 0.79236 1.03509 1.5587 2.604 1.00098 0.05232 53B 5.60211 35.01566 0.288 0.70929 1.16494 1.89475 2.688 1.07334 0.04796 54B 5.39051 36.893 0.228 0.74124 1.11671 1.4872 2.422 0.77184 0.05232 55B 5.43812 36.51473 0.252 0.7668 1.16865 1.56585 2.492 0.97686 0.0436 56B 5.28471 36.24854 0.294 0.79875 1.06477 1.6302 2.632 1.07937 0.05232 57B 5.51747 35.27251 0.282 0.74763 1.09074 1.86615 2.73 1.09143 0.05232 282 £2Z a a 8 It 8 cd DO g VII-8: XRF INSTRUMENT SETTINGS a: MAJOR ELEMENTS Element * Tube Crystal 0 Counter <? Peak 20 n Bkgrd 20 n Collimator <£> kv ma Si 60 40 T F 32.23 +2.3/-1.2 C Al 60 40 T F 37.88 +1.00 C Fe 60 40 L F 63.14 -1.6 c Ti 60 40 L F 86.35 +3.0/-1.0 c Ca 50 10 L F 113.34 +1.40 c K 60 40 L F 136.76 +2.00 F Mn 50 20 L F 63.14 -0.86 C Mg 30 60 T F 45.21 -1.2 C P 30 60 G F 141.12 -1.5 C b: MINOR ELEMENTS Element * Tube Crystal 0 Counter <? Peak 26 n Bkgrd 20 n Collimator £? kv ma Ba 60 40 L F 87.19 +1.20 F Co 60 40 L F 77.9 +0.54/-0.54 F Cr 60 40 L F 69.52 +1.00 C Cu 60 40 L F/S 45 -0.62 F Ni 60 40 L F/S 48.66 +1.2/-0.6 F Pb 60 40 L F/S 28.29 +0.5/-0.5 F Rb 60 40 L S 26.66 +0.4/-0.9 F Sr 60 40 L S 25.2 +0.6/-0.6 F V 60 40 L F 77.14 +4.0/-2.6 C Y 60 40 L S 23.83 +0.6/-0.6 F Zn 60 40 L F/S 41.78 +0.72 F Zr 60 40 L S 22.56 +0.74/-0.74 F Na 30 60 T F 55.25 +3.4/-1.7 C * All elements measured on the Ka line, except Ba and Pb (LP) 0 Crystals: L =lithium fluoride (200); T = thallium acid phthalate; G = germanium 7 Counters: F = flow using 90% Ar & 10% CH4; S = scintillation Q Collimators: C = coarse (480 um); fine (160 um) 285 VII-9: ACCURACY OF XRF RESULTS a: MAJOR ELEMENTS Element Al Fe Ti Ca K Si Mg P Na JA2 m 15.37 6.32 0.66 6.35 1.69 56.58 7.52 0.18 3.12 m 15.16 6.2 0.66 6.24 1.74 56.27 7.98 0.13 3.99 r 15.32 6.14 0.67 6.48 1.8 56.18 7.68 0.15 3.08 DFR -0.02 0.12 -0.01 -0.185 -0.085 0.27 0.07 0.005 0.475 RA 0.10% 2% -1.50% -2.90% -4.70% 0.50% 0.90% 3.30% 15.40% JB3 m 17.29 11.74 1.4 9.72 0.73 51.11 5.32 0.3 2.68 r 16.89 11.88 1.45 9.86 0.78 51.04 5.2 0.29 2.82 DFR 0.41 -0.18 -0.05 -0.14 -0.05 0.06 0.12 0.01 -0.14 RA 2.00% -1.50% -1.40% -1.40% -6.40% 0.10% 2.30% 3.40% -5% JG3 m 15.86 3.73 0.46 3.66 2.45 69.39 1.86 0.15 4.21 r 15.52 3.73 0.48 3.76 2.63 67.1 1.79 0.12 4.03 DFR 0.38 0 -0.02 -0.1 -0.18 2.3 0.07 0.03 0.18 RA 2.00% 0 -4.20% -2.70% -6.80% 3.40% 3.90% 25.00% 4.50% JA3 m 15.69 6.58 0.66 6.25 1.3 63.25 3.73 0.14 3.39 r 15.57 6.59 0.68 6.28 1.41 62.26 3.65 0.11 3.17 DFR 0.13 -0.01 -0.02 -0.03 -0.09 1.04 0.080.03 0.22 RA 0.80% -0.20% -2.90% -0.50% -6.40% 1.70% 2.20% 27.30% 6.90% JG2 m 12.87 1.03 0.02 0.71 4.45 80.75 -0.12 0.05 3.78 r 12.41 0.92 0.04 0.8 4.72 76.95 0.04 0 3.55 DFR 0.49 0.11 -0.02 -0.09 -0.27 3.85 0.05 0.23 RA 3.90% 12% -50% -11.30% -5.70% 5% 0 6.50% G2 m 15.05 2.7 0.47 1.94 4.2 69.27 0.56 0.12 4.37 r 15.38 2.66 0.48 1.96 4.48 69.08 0.75 0.14 4.08 DFR -0.28 0.04 -0.01 -0.02 -0.28 0.22 -0.19 -0.02 0.29 RA -1.80% 1.50% -2% -1% -6.30% 0.30% -25.30% -14.30% 7.10% All element concentrations expressed as wt.% oxides m = measured values r = recommended values DFR = difference from reccommended value RA = relative accuracy 286 &0 W S m J w OS o co co S C O O s 0-00 O C M C3 C M O s a. o. Q. X CO t l c u o C S O o co 3 > CO •s s E 2 _ . il < 6 287 GO W 1 w oi o l-> o C N CS Z 3.09 2.65 2.71 2.87 2.91 2.82 17.05 2.842 0.142 10 023 2.61 2.61 2.97 3.02 2.88 2.79 16.88 2.813 0.161 P205 (wt. %) 0.22 0.21 0.21 0.21 0.2 1.26 0.210 0.006 5.499 0.24 0.25 0.23 0.25 n os 0.25 1.47 0.245 0.008 ~ 6.235 MgO (wt. %) 2.83 2.78 2.79 2.83 2.75 16.77 2.795 0.028 2.013 2.96 2.92 2.88 2.87 2.9 2.86 17.39 2.898 0.034 A1203 (wt. %) 13.14 13.32 13.32 13.25 13.2 13.1 79.33 13.222 0.084 1.267 14.15 14.3 14.29 14.31 14.25 14.19 85.49 14.248 0.060 0 836 Si02 (wt. %) 68.84 68.69 68.89 68.84 /CO AO oy.us 68.07 412.41 68.735 0.319 0 927 63.79 64.08 64.25 64.53 64.47 385.4 64.233 0.247 0 770 K20 (wt. %) 1.63 1.6 1.59 1.63 1.57 9.63 1.605 0.021 2.668 1.96 1.95 1.93 1.93 1 Q1 1.71 1.92 11.6 1.933 0.017 L758 CaO (wt. %) 3.32 3.32 3.32 3.32 3.32 19.92 3.320 0.000 0.000 2.66 2.63 2.64 2.65 2.65 2.65 15.88 2.647 0.009 0/712 Ti02 (wt. %) 0.89 0.89 0.89 0.89 0.9 0.89 5.35 0.892 0.004 0 836 0.85 0.86 0.86 0.86 0.86 0.86 5.15 0.858 0.004 0 868 % -—• C O o C N u. 5.12 5.4 5.38 5.36 5.3 5.22 31.78 5.297 0.099 3.736 6 6.14 6.27 6.23 6.14 6.28 37.06 6.177 0.097 3.132 | Sample # 5B-A 5B-B 5B-C 5B-D 5B-E 5B-F SUM MEAN STD. DEV. RSDtS) 21B-A 21B-B 21B-C 21B-D 21B-E 21B-F SUM MEAN STD. DEV. RSD (•*>) ' o o X ca u > a Q "S X <N c o > 1 I Vi CU _> oi Q Vi Pi 288 PJ 9 m oi o Ba (ppm) | 619.8 609.4 593.4 ^9.7 7 609.8 621.9 3642 607.000 12.629 *t. lOl 587.2 635.3 618.9 601 602.2 540.5 3585.1 597.517 29.654 9 926 Cr(ppm) 145.9 147.6 144.7 147.1 149.5 153.1 887.9 147.983 2.724 3.682 138.5 140.4 147.8 1 in Q 1.5/. o 135.1 122.2 821.8 136.967 7.678 11 212 1= o. a .—• > 152 155.2 151.4 147.2 150.5 154.3 910.6 151.767 2.609 3.439 138 148.3 148 145.9 146.5 117.2 843.9 140.650 11.040 15.698 Mn (ppm) 600.1 609.1 585.5 575 606.1 602.3 3578.1 596.350 12.115 4.063 613.1 637.4 639.3 608.3 614.1 557.6 3669.8 611.633 26.982 8 823 Co (ppm) 92.8 98.9 79.4 72.5 68 72.3 483.9 80.650 11.390 28.246 48.8 50 49 41.6 41.1 31.7 262.2 43.700 6.442 29 481 Ni (ppm) 42.9 37.3 41.2 42.4 40.8 39.2 243.8 40.633 1.905 9.376 40.6 40.9 42 40.9 43.6 40.9 248.9 41.483 1.045 5 037 Cu (ppm) 20.7 20.2 17.3 22.9 18.2 21.6 120.9 20.150 1.910 18 961 32.4 32.5 31.6 32.2 32.1 29 189.8 31.633 1.212 7.663 Zn (ppm) « 2 " J ^ n ^ S S c~ f~ 446.1 74.350 1.087 2.925 82.1 84.2 82.2 83 84.2 85.9 501.6 83.600 1.328 3 177 I s a a £ 15.7 14.1 6.6 11.7 16.3 7.1 71.5 11.917 3.869 64.932 11.7 11.6 14.7 13.4 15.9 23.1 90.4 15.067 3.905 51.836 Rb (ppm) 43 46.2 41.9 46.3 40.1 42.8 260.3 43.383 2.233 10 293 43.2 43.7 49.3 46.7 42.5 52.1 277.5 46.250 3.502 15.145 Sr (ppm) 262.1 258.5 260.5 266.1 262.9 264.3 1574.4 262.400 2.465 1.879 246.3 242.4 238.9 235.1 240.5 256.9 1460.1 243.350 6.943 5 706 Y (ppm) 21.6 19.1 21.6 19.7 22.6 22.2 126.8 21.133 1.285 12 165 18.1 19 20.7 18.4 21.8 19.4 117.4 19.567 1.300 13 284 Zr (ppm) 179.1 175.2 180.1 177.6 177.2 177.4 1066.6 177.767 1.543 1 736 148.1 144 144 143.4 147 149.4 875.9 145.983 2.300 3.150 | Sample # 5B-A 5B-B 5B-C 5B-D 5B-E 5B-F SUM MEAN STD. DEV. RSD (<*) 19A-A 19A-B 19A-C 19A-D 19A-E 19D SUM MEAN STD.DEV. RSD (9c) 289 VII-11: A N A L Y T I C A L PRECISION F O R GAS C H R O M A T O G R A P H Y / T H E R M A L C O N D U C T I V I T Y A N A L Y S E S Sample # Total %N Total %C 5B-A 0.059 1.013 5B-B 0.061 1.025 5B-C 0.055 0.996 5B-D 0.059 0.979 5B-E 0.065 0.984 5B-F 0.054 0.935 5B-G 0.058 0.944 5B-H 0.056 0.965 SUM 0.467 7.839 MEAN 0.058 0.980 STD. DEV. 0.003 0.030 RSDC.) 11.623 6.021 21B-A 0.132 1.238 21B-B 0.144 1.254 21B-C 0.135 1.224 21B-D 0.133 1.231 21B-E 0.138 1.234 21B-F 0.133 1.212 21B-G 0.128 1.184 21B-H 0.136 1.191 SUM 1.080 9.768 MEAN 0.135 1.221 STD. DEV. 0.004 0.022 RSD(%) 6.500 3.658 RSD = Relative standard deviation (2 X Std. Dev./Mean) X 100 290 VII-12: ANALYTICAL PRECISION FOR COULOMETRY Instrument: Blue Test tube # Sample # Wt. sample (ug) ug Carbon % carb C 14 21Bb 84310 42 0.039 8 21Bc 82720 37 0.034 67 21Bd 98790 40.7 0.032 10 21Be 89840 39.4 0.034 21 21Bf 90710 44.8 0.039 2 21Bg 88670 49.6 0.046 SUM 0.224 MEAN 0.037 STD. DEV. 0 005 RSD (%) 25.028 3 19Da 97320 33.4 0.025 23 19Db 98760 33.9 0.026 45 19Dd 99020 29.1 0.020 16 19De 87530 27.7 0.021 54 19Df 87910 28.8 0.023 27 19Dg 88170 34.1 0.032 SUM 0.148 MEAN 0.025 STD. DEV. 0.004 RSD (%) 32.227 Instrument: Grey Test tube # Sample # Wt. sample (ug) ug Carbon % carb C 1 21Ba 99150 88.25 0.079 26 21Bb 84410 78.33 0.081 18 21Bc 89040 83.2 0.083 16 21Bd 92190 95.06 0.093 26 21Be 97410 101.14 0.094 9 21Bf 84380 92.23 0.098 SUM 0.527 MEAN 0.088 STD. DEV. 0.007 RSD (%) 16.177 6 19Da 94380 70.41 0.064 27 19Db 93550 69.5 0.064 2 19Dc 91270 69.69 0.066 24 19Dd 96780 73.84 0.066 46 19De 85700 70.89 0.071 55 19Df 85750 71.92 0.073 SUM 0.404 MEAN 0.067 STD. DEV. 0.003 RSD (%) 10.015 RSD = Relative standard deviation (2 X Std. Dev./Mean) X 100 291 [ ratiol C N o i N O s o 00 p-t o o O N 00 O N 5 o 00 Tf 00 •* p-N O t m Tf m m C S s C S c n g N O o Tr O N o o o 00 O N Tf C S o o o c n N O r-c n m O N m N O C S o O N m N O r-m p~ C S TI-C S r-c n Tf Tf N O c n T ? d i r i r-* P-" p-* i r i N O NO* r» i r i 00 N O P-* r-* N O Tf* N O N O i r i N O NO* NO* 0 0 i r i N O r-* i r i r» N O 0 u organic o c n Tf p-m o in o O N c n c n c n Tf N O C S O N o •* m 0 0 N O 00 m c n O N N O o t— o N O o o m N O 00 C S TT in t m C S c n C S C S p-c n p~ c n O N C S c n N O c n TI-C S o Tf organic © d d d d d d d d d d d d d d d d d d d d d d d d d d d d d 4-* e Instrume o tu 9 5 u 9 5 U 3 tu 9 s u 9 CO > N H O >> H O B O 1 O O to 9 00 tu 9 s tU 9 a tu 9 03 O 1 >> O 9 5 tu 9 ffl tu 9 CQ tU 9 03 I 1 O O >. 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