"Science, Faculty of"@en . "Earth, Ocean and Atmospheric Sciences, Department of"@en . "DSpace"@en . "UBCV"@en . "Hawke, Michelle Irene"@en . "2009-12-23T00:24:12Z"@en . "2004"@en . "Doctor of Philosophy - PhD"@en . "University of British Columbia"@en . "Monitoring and remediation of anthropogenic trace elements requires knowledge of the magnitude of emissions and their fate in the environment. This study examines the role of organic sediments in the partitioning of Sb, As, Cd, Cu, Ni, Pb and Zn in the environment surrounding a lead-zinc smelter.\r\nTrace element concentrations in peat profiles were highest near the smelter and decreased with distance. Peat concentrations were compared to mineral soil concentrations and to atmospheric deposition rates. Anomalies between peat concentrations and deposition rates identify locations of secondary source impact. Concentrations are higher in impacted peats than in corresponding soils, indicating preferential sequestration.\r\nAssigning a geochemical baseline and differentiating between trace element sources is difficult in areas with heterogeneous geochemistry. Two geochemical fingerprinting methods were applied to estimate smelter impact: normalisation to \"conservative elements\" and rare earth element patterns.\r\nInterpretation of \"conservative element\" ratios proved difficult, due to concentration variability. It was concluded that conservative elements may not represent a geochemical baseline.\r\nLight rare earth element enrichment was noted in peats and other sampling media closest to the smelter, but not in smelter feedstock or wastes, suggesting that LREE enrichment is overprinted from background geochemistry.\r\nSources of trace element-rich particles include stack emissions and fugitive and geogenic dust. Peat ash was examined by SEM-EDX to determine the morphology and elemental composition of the particulates. Rounded smelter-emitted particles are present in peats sampled close to the smelter. Weathering and mobilisation are indicated by changes in chemistry between fresh and weathered particles. Angular fugitive dust sulphide particles also occur.\r\nSequential leaching of peats and soils illustrates that trace element speciation is controlled by environmental conditions and by source. In smelter-impacted peats, elements are sequestered as exchangeable, carbonate, Fe-oxide or organic species, indicating precipitation from solution. Non-impacted peats contain higher proportions of residual and sulphide species.\r\nEnvironmental parameters impact peat diagenesis and influence element behaviour. An organic petrographic evaluation of smelter-impacted peats aids in determining past and current conditions. A well-humified profile, which indicates aerobic conditions, contained abundant Fe-oxide species. Profiles containing maceral assemblages that indicate anaerobic conditions contained sulphide and organic species."@en . "https://circle.library.ubc.ca/rest/handle/2429/17082?expand=metadata"@en . "ELEMENTAL CHARACTERISTICS OF ORGANIC DEPOSITS FROM AN AREA SURROUNDING A LEAD-ZINC SMELTER: CONCENTRATION, DISTRIBUTION, MODE OF OCCURRENCE AND MOBILITY. By MICHELLE IRENE HAWKE B.Sc., The University of Guelph, 1994 M.Sc., The University of Guleph, 1997 A THESIS SUBMITTED IN PARTIAL FULFILMNET OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY In THE FACULTY OF GRADUATE STUDIES DEPARTMENT OF EARTH AND OCEAN SCIENCES We accept this thesis as*conformine to the required standard THE UNIVERSITY OF BRITISH COLUMBIA March 2004 \u00C2\u00A9 Michelle I. Hawke, 2004 Statement of Go-Authorship regarding Chapter 7 of the PhD thesis entitled \"Elemental characteristics of organic deposits from an area surrounding a Pb-Zn smelter; Concentration, distribution, mode of occurrence and mobility\", fey Michelle Hawke The chapter in question is entitled \"Comparing maceral ratios from tropical peatlands with assumptions from coal studies. Do classic coal petrographic interpretation methods have to be discarded? and was published as WQst, R.AJL, Hawke, MX and Bustin, R.M. (2001) Comparing maceral ratios from tropical peatlands with assumptions from coal studies: do classic coal petrographic interpretation methods have to be discarded? International Journal of Coal Geology, 48: 115-132. and was included in the PhD thesis of R.A.J. WUst (2001) This research was conducted jointly between Raphael Wust and Michelle Hawke with contributions by Dr. R. Marc Bustin. Michelle Hawke's contribution to the research included the following: -developing the concept behind the research with her co-authors, -analytical work, in this case preparation of peat samples for reflected light microscopy, and microscopic analysis (point counting), -interpretation of microscopic analysis Hie resulting paper was written as a collaborative effort, primarily between Michelle Hawke and Raphael Wiist, with both authors contributing approximately equally to the finished paper, I agree that the above statement is an accurate description of Michelle Hawke's involvement with the preparation of the work in question. Note: Chapter 7, as described in the above statement, is presented in the final version of the thesis as Appendix A. Abstract Monitoring and remediation of anthropogenic trace elements requires knowledge of the magnitude of emissions and their fate in the environment. This study examines the role of organic sediments in the partitioning of Sb, As, Cd, Cu, Ni, Pb and Zn in the environment surrounding a lead-zinc smelter. Trace element concentrations in peat profiles were highest near the smelter and decreased with distance. Peat concentrations were compared to mineral soil concentrations and to atmospheric deposition rates. Anomalies between peat concentrations and deposition rates identify locations of secondary source impact. Concentrations are higher in impacted peats than in corresponding soils, indicating preferential sequestration. Assigning a geochemical baseline and differentiating between trace element sources is difficult in areas with heterogeneous geochemistry. Two geochemical fingerprinting methods were applied to estimate smelter impact: normalisation to \"conservative elements\" and rare earth element patterns. Interpretation of \"conservative element\" ratios proved difficult, due to concentration variability. It was concluded that conservative elements may not represent a geochemical baseline. Light rare earth element enrichment was noted in peats and other sampling media closest to the smelter, but not in smelter feedstock or wastes, suggesting that LREE enrichment is overprinted from background geochemistry. Sources of trace element-rich particles include stack emissions and fugitive and geogenic dust. Peat ash was examined by SEM-EDX to determine the morphology and elemental composition of the particulates. Rounded smelter-emitted particles are present in peats sampled close to the smelter. Weathering and mobilisation are indicated by changes in chemistry between fresh and weathered particles. Angular fugitive dust sulphide particles also occur. Sequential leaching of peats and soils illustrates that trace element speciation is controlled by environmental conditions and by source. In smelter-impacted peats, elements are sequestered as exchangeable, carbonate, Fe-oxide or organic species, indicating precipitation from solution. Non-impacted peats contain higher proportions of residual and sulphide species. Environmental parameters impact peat diagenesis and influence element behaviour. An organic petrographic evaluation of smelter-impacted peats aids in determining past and current conditions. A well-humified profile, which indicates aerobic conditions, contained abundant Fe-oxide species. Profiles containing maceral assemblages that indicate anaerobic conditions contained sulphide and organic species. Table of Contents Abstract ii List of Figures viii List of Tables xii Preface xiv Acknowledgements xv Chapter 1: Introduction \u00E2\u0080\u00A2\u00E2\u0080\u00A2 1 1.1 Monitoring of Anthropogenic Trace Elements 2 1.2 Peatlands as a Sink for Trace Elements 2 1.3 The Teck-Cominco Trail Smelter 3 1.4 Objectives 3 1.5 Chapter Outline 5 1.6 Other Research-Organic Petrography of Tasek Bera, Malaysia 7 1.7 References 7 Chapter 2: Trace elements in organic deposits in the area surrounding a base metal smelter . ' \u00E2\u0080\u00A2 \u00E2\u0080\u00A2 9 2.1 Introduction 10 2.1.1 The Inorganic Geochemistry of Peatlands ' 10 2.1.2 Atmospheric trace element deposition and the mobility of trace elements within the peat profile \u00E2\u0080\u00A2 10 2.2 Study Area 11 2.3 Methodology 16 2.3.1 Peat Sampling and Analytical Protocol - 16 2.3.2 Soil Sampling _ _ 17 2.3.3 Moss Monitoring Rates of Aerial Deposition 18 2.4 Results 18 2.4.1 Trace Element Concentrations in the Peats 18 2.4.1.1 ComincoSite 19 2.4.1.2 Thunder Road Site 26 2.4.1.3 Champion Lakes Site 28 2.4.1.4 Bombi Summit Site 30 2.4.2 Moss Monitoring Results ; 30 2.4.3 The distribution of trace elements in the environs of the stationary sources 34 2.5 Discussion 37 2.6 Conclusions 40 2.7 References 41 Chapter 3: Geochemical finger-printing in an anthropogenically-impacted area of heterogenous geochemistry\u00E2\u0080\u0094Can rare earth elements and conservative element ratios be used to identify source? 44 3.1 Introduction 45 3.2 Study Area ; 45 3.3 Methodology 46 3.3.1 Peat Sampling and Analytical Protocol 46 3.3.2 Soil Sampling 46 3.3.3 Elemental Analysis 49 3.4 Trace Element/Conservative Element Concentrations: A Viable Normalisation Parameter? 49 3.4.1 Introduction 49 3.4.1.1 Selection of a geochemical background value 50 3.4.1.2 Selection of conservative elements 51 3.4.2 Results 52 3.4.2.1 Cominco Profile 52 3.5.2.2 Thunder Road Profile 55 3.5.2.3 Champion Lakes Profile 55 3.4.2.4 Bombi Summit Profile 72 3.4.3 Discussion 72 3.5 Rare Earth Element Enrichment Patterns 73 3.5.1 Introduction 73 3.5.1.1 REE behaviour in the environment 74 3.5.1.2 REEs as Geochemical Tracers 75 3.5.2 Results 76 3.5.2.1 REE concentrations of smelter materials 76 3.5.2.2 Moss Monitoring Station Data 76 3.5.2.3 Peats 76 3.5.2.4 Soil 80 3.5.2.3 Peat Data Normalised to Soil Data 84 3.5.2.5 Stream Sediment Data 84 3.5.3 Discussion 88 3.6 Conclusions _ 8 9 3.7 References 90 Chapter 4: Particulate matter in peat from the environs of a Pb-Zn smelter: determining geogenic and anthropogenic input 92 4.1 Introduction 93 4.2 Sampling Locations 94 4.3 Methodology 97 4.4 Results and Discussion 98 4.4.1 Trace element concentration 98 4.4.2 Mineralogy 99 4.4.2.1 Cominco Site 99 4.4.2.2 Thunder Road Site 100 4.4.2.3 Champion Lakes Site 100 4.4.3 SEM-EDX investigation of peat ash 102 4.4.3.1 Cominco Site 105 4.4.3.2 Thunder Road 105 4.4.3.3 Champion Lakes 106 4.5 Discussion 134 4.5.1 SEM-EDX Investigations of Smelter-Related Media 134 4.5.1.1 Smelter Wastes 134 4.5.1.2 Moss Monitoring Stations 134 4.5.1.3 Stream Sediments 135 4.5.2 Environmental Significance 135 4.6 Conclusions 137 4.7 References 137 Chapter 5: Determination of the mode of occurrence of trace elements in peats and soils from the vicinity of a Pb-Zn smelter using a sequential extraction procedure 139 5.1 Introduction 140 5.2 Study Area 141 5.3 Sampling Locations 141 5.3.1 Cominco Site 141 5.3.2 Thunder Road Site 143 5.3.3 Champion Lakes Provincial Park _ ' 143 5.4 Methodology 144 5.5 Results 147 5.5.1 Summary of Results from Previous Studies 147 5.5.2 Sequential Leaching Results 148 5.5.2.1 Cominco Site 148 5.5.2.2 Thunder Road 151 5.5.2.3 Champion Lakes 162 5.5.2.4 Comparison to results of sequential leaching from soil and stream sediment samples 168 5.6 Discussion 171 5.6.1 Controls on Speciation _ _ 171 5.6.1.1 Adsorption 171 5.6.1.2 The Carbonate Fraction 172 5.6.1.3 The Reducible Fraction 173 5.6.1.4 The Sulphide Fraction 174 5.6.1.5 Organic complexation 176 5.6.1.6 The Residual Fraction 177 5.6.2 The role of source material in determining mode of occurrence 178 5.7 Conclusions 179 5.8 References 180 Chapter 6: The organic petrographic characteristics ofpeats from an area of high trace element input 185 6.1 Introduction 186 6.2 Sampling Locations 187 6.3 Methodology 191 6.4 Results and Discussion 191 6.4.1 Trace Element Concentrations 191 6.4.2 Organic Petrography and Mode of Occurrence 194 6.4.2.1 Cominco 194 6.4.2.2 Thunder Road Profile 200 6.4.2.3 Champion Lakes Profile 204 6.4.2.4.Bombi Summit Profile 205 6.4.3 Inorganic Matter 6.4.4 Organic Sequestration of Metals-the role of peat type and humification 6.5 Conclusions 6.6 References Chapter 7: Conclusions 7.1 Key findings resulting from this research 7.1.1 Trace element concentrations in organic deposits in the area surrounding a base metal smelter 7.1.2 Geochemical finger-printing, using element ratios and REE signatures 7.1.3 SEM-EDX study of peat ash 7.1.4 Sequential extraction 7.1.5 Organic petrography 7.2 Suggestions for Future Research APPENDIX A: Comparing maceral ratios from tropical peatlands with assumptions from coal studies. Do classic coal petrographic interpretation methods have to be discarded? 1 A.A.1 Introduction A.A. 1.1 Maceral Ratio Indexes A. A. 1.2 Organic composition of tropical peats A.A. 2 Tropical Tasek Bera - physiographic settings, peat accumulation and spatial distribution 223 A.A.2.1 Peat Formation A.A.2.2 Climate A.A.2.3 Biological diversity of the Tasek Bera wetland A.A.3 Methods A.A.4 Results and Discussion A.A.4.1 Pandanus and Lepironia environment (Sites B64 and B102) A.A.4.2 Swamp Forest Environment (Site B83) A.A.4.3 Maceral Ratio Diagrams A.A.4.4 Modern peat depositional environments - a key to the past_ A.A.4.5 Implications for coal studies A.A.5 Conclusions A.A.6 References List of Figures Figure. 1-1. Trail, British Columbia, in 1904 (a), 1944 (b) and 2000. Photos a and b were obtained from the City of Trail Archives (2003). 4 Figure 2-1. Geology of the Trail area and the location of the smelter and sampling sites. After Little, (1982). 13 Figure 2-2. Concentration of trace elements as a function of the radial distance from the smelter. 23 Figure 2-3. Concentration of selected trace elements within the Cominco profiles. 24 Figure 2-4. Concentration of selected trace elements in the Thunder Road profiles. 27 Figure 2-5 Concentration of trace elements in the Champion Lakes profiles. 29 Figure 2-6. Concentration of trace elements in the Bombi Summit profile. 31 Figure 2-7. Concentration of trace elements in peats relative to the differential concentrations in peats versus mineral soils. 39 Figure 3-1. Geological map of the Trail area showing the location of the smelter and sampling sites. Modified from Little (1982). 47 Figure 3-2. Concentration of trace elements in the peat profiles. BSed = basal sediment. 57 Figure 3-3. Normalised element ratios using soil and rock for the Cominco profile. Bulk concentration data is plotted on the primary (top) axis, while element ratios are plotted on the secondary (bottom) axis. 63 Figure 3-4. Normalised element ratios using soil and rock for the Thunder Road profile. Bulk concentration data is plotted on the primary (top) axis, while element ratios are plotted on the secondary (bottom) axis. 65 Figure 3-5. Normalised element ratios using soil and rock for the Champion Lakes profile. Bulk concentration data is plotted on the primary (top) axis, while element ratios are plotted on the secondary (bottom) axis. 67 Figure 3-6. Normalised element ratios using soil and rock for the Bombi Summit profile. Bulk concentration data is plotted on the primary (top) axis, while element ratios are plotted on the secondary (bottom) axis. ; 69 Figure 3-7 a. Plot of the concentrations of Ti and Zr versus the peat ash contents, b. Whisker-Box diagram showing the spread of Ti/Zr ratios for each profile, where the median value is represented by the dot in the middle of the box, the upper and lower extent of the box represent the 75th and 25th percentile, respectively, and the lines extending from the box represent the range of data. 71 Figure 3-8. Chondrite nomalised REE pattern for selected smelter feedstock and waste samples. 77 Figure 3-9. Chondrite normalised REE pattern for median values of REE's deposited on moss monitoring stations near the peat sampling sites and the Zn-concentrate unloading site. 78 Figure 3-10. Chondrite normalised REE's for peat profiles. 82 Figure 3-11. Chondrite normalised REE's for mineral soils near the peat sampling sites and near the ore concentrate unloading site. 83 Figure 3-12. REE's for peat normalised to the nearest mineral soil (0-3 cm depth). 85 Figure 3-13. REE's for peat normalised to the nearest mineral soil (3-10 cm depth). 86 Figure 3-14. Chondrite normalised REE pattern for stream sediments collected near the peat sampling sites and near the Zn-concentrate unloading site. 87 Figure 4-1. Geological map of the Trail area (from Little, 1982) showing sampling locations. 96 Figure 4-2. Example of a geogenic particle (sphalerite) from the Champion Lakes 103 sampling site. The number on the EDX spectra refers to the frame number on Table 4-10. 103 Figure 4-3. Examples of heat-treated spherical or rounded metallic particles (4a and c) emitted from the smelter, observed in the Thunder Road 7-8 cm peat. Also present are a spherical silicate fly ash particle (4b) and a Zn-containg Fe-precipitate (4d). Numbers correspond to frame numbers in Table 4-9. 104 Figure 4-4. Examples of rounded particles containing Pb and Zn present in the Cominco 1-2 cm sample. Numbers on the EDX spectra refer to the Frame number on Table 4-5. 107 Figure 4-5. Example of a subangular particle containing Zn from the Cominco 1-2 cm sample. Number on the EDX spectra refers to the Frame number on Table 4-5. ; 108 Figure 4-6. Example of a rounded particle of anthropogenic origin containing Zn and Fe from the Cominco 4-5 cm sample (3a on Table 4-6). The geochemistry of examples of other particulate matter observed within the frame is indicated in spectras 3band 3c. 112 Figure 4-7. Example of a subangular particle of geogenic origin containing Pb, from the Cominco 4-5 cm sample (4a on Table 4-6). Spectras 4b-d indicate the geochemistry of other observed particulates within the frame. 113 Figure 4-8. Fe-Zn-Cu precipitate from the Cominco 17-20 cm sample (9a on Table 4-7). Examples of geogenic particles are also pictured (9b and c). 119 Figure 4-9. Geogenic particle containing Pb, from the Cominco 17-20 cm sample (6a on Table 4-7). The EDX spectra of other particulate matter observed within the frame are also presented (6b and c ) _ 120 Figure 4-10. Spherical metal enriched particle emitted from the smelter, from the Thunder Road 0-1 cm sample (4a on Table 4-8). 123 Figure 4-11. Examples of Zn-containing particles from the Thunder Road 0-1 cm sample, a.: weathered geogenic Zn sulphide mineral, c and d: Fe-Zn precipitates (frame 3 on Table 4-8). An example of the geochemistry of other particulate material observed within the frame is illustrated by spectra b. 124 Figure 4-12. Example of native Zn particle from the Thunder Road 0-1 cm sample (Frame 5 ,Spot a on Table 4-8), with a quartz particle (b). 125 Figure 4-13. Angular geogenic Zn-rich particle (a) and a spheroidal fly ash particle from the Thunder Road 7-8 cm sample (Frame 2 on Table 4-9). 128 Figure 4-14. Agglomeration of Zn rich particles, including a subangular native Zn particle (a), Zn-rich precipitates (b and c) and (d) a diatom with Zn precipitated on the surface from the Thunder Road 17-20 cm sample (Frame 3 on Table 4-9). 129 Figure 4-15. Diatom-rich ash material from the Champion Lakes 3-4 cm sample (e.g., b). Non-biogenic materials include an angular Ti-rich geogenic particle (a) and a glassy silicate fly ash particle with slight Ca enrichment.(c) (Frame 1 on Table 4-10). 132 Figure 4-16. Geogenic particles containing Si, Ca, Fe, Al and S from the Champion Lakes 3-4 cm sample (spots a, c, d and e). Spot (b) is a glassy Si fly ash particle with slight S, Ca and Fe enrichment. (Frame 6 on Table 4-10). 133 Figure 4-17. Examples of particulate matter captured by the moss-monitoring stations in the Trail area. a. Geogenic quartz particle, b. Rounded and \"fluffy\" PbO particles formed by thermal alteration in the smelter, and angular ZnS particles from fugitive emissions, c. Angular ZnS particles derived from fugitive dust, collected near an ore and slag storage facility. From Goodarzi et al., 2003. 136 Figure 5-1. Geological map of the Trail, British Columbia area, with sampling locations for peats and stream sediments indicated. 142 Figure 5-2. Total element concentrations within the Cominco profile. BSed = basal mineral sediment. 150 Figure 5-3. Absolute concentrations (in ppm) for sequentially extracted fractions in the Cominco profile, including the basal mineral sediment (BSed). Concentrations for the Cominco mineral soil (MS) and the Rossland background soil (BG) are included below the results for the peat profile. 152 Figure 5-4. Relative concentrations (%) for sequentially extracted fractions in the Cominco profile, including the basal mineral sediment (BSed). Relative concentrations for the Cominco mineral soil (MS) and the Rossland background soil (BG) are included below the results for the peat profile. 153 Figure 5-5. Total element concentrations within the Thunder Road profile, including basal sediment (Bsed). 157 Figure 5-6. Absolute concentrations (in ppm) for sequentially extracted fractions in the Thunder Road profile, including the basal mineral sediment (BSed). 158 Figure 5-7. Relative concentrations (%) for sequentially extracted fractions in the Thunder Road profile, including the basal mineral sediment (BSed). 159 Figure 5-8. Total element concentrations within the Champion Lakes profile. 163 Figure 5-9. Absolute concentrations (in ppm) for sequentially extracted fractions in the Champion Lakes profile, and for a nearby mineral soil (MS). 164 Figure 5-10. Relative concentrations (%) for sequentially extracted fractions in the Champion Lakes profile and a nearby mineral soil (MS). 165 Figure 5-11. Relative concentrations (%) for sequentially extracted fractions in selected stream sediments. 170 Figure 6-1. Geological map of the Trail area, indicating the location of sampling sites. 189 Figure 6-2. Location photographs a. Teck-Cominco smelter b. Cominco sampling site c. Cominco peat profile duing sampling d. Thunder Road sampling site e. Champion Lakes sampling site f. Bombi Summit samplig site 190 Figure 6-3. Organic petrographic composition of the peat profiles, expressed as volume % = 193 Figure 6-4 . Graph of humification index versus total inertinite content. 195 Figure 6-5. Relative concentrations (%) for sequentially extracted fractions in the Cominco profile, including basal mineral sediment (Bsed). 197 Figure 6-6. Relative concentrations (%) for sequentially extracted fractions in the Thunder Road profile, including basal mineral sediment (Bsed). 201 Figure 6-7. Relative concentrations (%) for sequentially extracted fractions in the Champion Lakes profile. 206 Figure 6-8. Examples of mineral matter found within the Cominco profile. A. Sulphide mineral, probably pyrite B. and C. highly reflecting carbonaceous material (fly ash) produced from the combustion of coal in the smelter operation. D. diatom permineralised with sulphides. E. pollen grain permineralised with sulphides F. oxidised framboidal pyrite and quartz grain. 208 Figure 6-9. Examples of mineral matter found within the Champion Lakes profile. A. woody material permineralised by sulphides. B. fly ash particle. C. particle of sulphide mineral, probably sphalerite. 209 Figure A-l: Location map of the Tasek Bera Basin (Tasek = lake) illustrating the dendritic drainage pattern, extent of peat accumulation (gray shading) and peat swamp tributary names (Paya = swamp, swampy area). Inset map shows the location of the Tasek Bera Basin in the states of Pahang and Negeri Sembilan, Peninsular Malaysia. Selected core sites are indicated. Sites B64 and B102 are from a Lepironia articulata and Pandanus helicopus environment, while site B83 is situated in true swamp forest. 225 Figure A-2: Core B64 from Lepironia and Pandanus environment. The site was waterlogged at the time of core collection. Strati graphic description and chemical characterization of the profile and petrographic composition. Petrographic results are reported on a volume percent basis. The huminites (vitrinites) are often dominant with various amounts of liptinites. Inertinites, mainly funginite, dominate the lower part of this littoral core. 230 Figure A-3: Core B102 from Lepironia and Pandanus environment. The site was waterlogged at the time of core collection. Stratigraphic description and chemical characterization of the profile and petrographic composition. Petrographic results are reported on a volume percent basis. The huminites (vitrinites) are often dominant with various amounts of liptinites. Inertinites, mainly funginite, dominate the lower part of this littoral core. 233 Figure A-4: Core B83 from the swamp forest environment of Paya Belinau (Fig. 1). The site was waterlogged at the time of core collection. Stratigraphic description and chemical characterization of the profile and petrographic composition. Petrographic results are reported on a volume percent basis. The huminites (vitrinites) are often dominant with various amounts of liptinites. Inertinites, mainly funginite, dominate the middle part of the swamp forest deposits. 238 Figure A-5: Three cross-plots of maceral ratios commonly used for paleodepositional interpretation in coal geology. A) Inertinite versus textinite plus texto-ulminite. B) GI versus TPI. The Diessel (1982) paleodepositional environments are indicated. C) Inertinite versus textinite divided by texto-ulminite. 242 List of Tables Table 2-1. Location, bedrock geology, vegetation and general notes on the sampling locations. Details of bedrock geology are from Little, 1982; Hoy and Andrew, 1991. 12 Table 2-2. Compilation of published geochemistry for the bedrock underlying the peat sampling sites. Data for the Nelson Intrusives is presented as published in Sevigny (1990). Data for the Elise Formation is presented as published in Beddoe-Stephens and Lambert (1981). 15 Table 2-3. Concentrations of trace elements measured within peats and mineral soils. Environmental soil quality guideline data provided from B.C. Ministry of Water, Land and Air Protection (2002) lists element concentrations at which soils must be relocated to non-agricultural lands, and at which a permit is required for disposal. Environment Canada Soil Quality Guidelines (2002) list generalized trace element concentration guidelines for agricultural, residential/parkland and industrial land uses. 22 Table 2-4. Calculated Peat Enrichment Factors (PEFs) for peats relative to nearby mineral soils. 25 Table 2-5. Concentration of selected trace elements in the moss used as sampling media for moss monitoring stations in the Trail area. The concentrations are statistically corrected for geogenic input, as described in Goodarzi et al., (2001; 2003). Cumulative impact over the two-year sampling period is indicated in the right column. 32 Table 2-6. Relative concentrations of trace elements in the Thunder Road and Champion Lakes peats and soils, as compared to Cominco peats and soils. Relative rates of deposition as determined by moss monitoring stations are calculated from data in Goodarzi et al., 2001; 2003. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 36 Table 3-1 Description of the sampling sites. \u00E2\u0080\u00A2 48 Table 3-2. Mineralogy of the peat profiles as determined by X-ray diffraction. Methodology is described in Chapter 4. 53 Table 3-3. Concentration of selected elements in the peat profiles. 56 Table 3-4. Element concentrations in mineral soils (3-10 cm depth) corresponding to the peat sampling sites, and calculated element ratios. 58 Table 3-5. Element ratios normalized to mineral soil for Ti and Zr. 59 Table 3-6. Selected published geochemical data and the resulting caluculated conservative element ratios from the bedrock geology of the Trail Pluton (Sevigny, 1990) and the Elise Formation. (Beddoe-Stephens and Lambert, 1981) 61 Table 3-7. Element ratios normalised to bedrock geochemical data listed in Table 3-6. 62 Table 3-8. Concentration of REE's and normalized La/Lu ratios from selected smelter feedstock and waste samples. 77 Table 3-9. Concentration of REE's and normalized La/Lu ratios for mineral soils and moss monitoring stations near the peat sampling sites, and near the ore concentrate unloading site. 78 Table 3-10. Concentration of REE's and normalized La/Lu ratios. 81 Table 4-1. Compilation of published geochemical data, for the Nelson Intrusives (Sevigny, 1990) and the Elise Formation (Beddoe-Stephens and Lambert, 1982). ' 95 Table 4-2. Description of the sampling sites: location, bedrock geology, vegetation and conditions within the peat profile. 97 Table 4-3. Bulk concentrations of selected trace elements within the peat profiles. 99 Table 4-4. Mineralogy as determined by X-ray diffraction. 101 Table 4-5. Summary of the observations from the Cominco 1-2 cm sample. \"Frame\" and \"spot\" refer to the numbers on the EDX spectra for the figures. Elements present in high concentrations are listed in bold face type. 109 Table 4-6. Summary of the observations from the Cominco 4-5 cm sample. \"Frame\" and \"spot\" refer to the numbers on the EDX spectra for the figures. Elements present in high concentrations are listed in bold face type 114 Table 4-7 Summary of the observations from the Cominco 17-20 cm sample. \"Frame\" and \"spot\" refer to the numbers on the EDX spectra for the figures. Elements present in high concentrations are listed in bold face type. 116 Table 4-8 Summary of the observations from the Thunder Road 0-1 cm sample. \"Frame\" and \"spot\" refer to the numbers on the EDX spectra for the figures. Elements present in high concentrations are listed in bold face type. 121 Table 4-9 Summary of the observations from the Thunder Road 7-8 cm sample. \"Frame\" and \"spot\" refer to the numbers on the EDX spectra for the figures. Elements present in high concentrations are listed in bold face type. 126 Table 4-10. Summary of the observations from the Champion Lakes 3-4 cm sample. \"Frame\" and \"spot\" refer to the numbers on the EDX spectra for the figures. Elements present in high concentrations are listed in bold face type. 130 Table 5-1. Organic carbon and total sulphur concentrations of selected samples. 151 Table 6-1. Description of sampling sites, bedrock geology and vegetation. 188 Table 6-2. Concentrations of trace elements in the peat profiles. 192 Table A-l: Data analyses of the three representative cores of the Tasek Bera Basin for petrographic investigations. Core number, sample depth in cm, ash content in wt-%, carbon content in wt-% and pH are given. The carbon content of B83 and B102 was estimated based on the linear relationship between ash and carbon content of over 130 samples from the Tasek Bera mire deposit. (Wiist, 2001).235 Preface This thesis is a component of the multidisciplinary Geological Survey of Canada-Teck Cominco project. The thesis is written in the form of six separate research manuscripts, each of which is presented as a thesis chapter, and each of which is either intended for publication as a research paper at a future date but has yet to be submitted, or has already been published. All chapters pertaining to the Teck-Cominco project (1-7) are original research, conceived and written by Michelle Hawke under the supervision and direction of Dr. Marc Bustin and Dr. Fariborz Goodarzi. Appendix A is a collaborative effort between Raphael Wiist and Michelle Hawke under the supervision of Dr. Marc Bustin. This paper has been published as Wiist et al. (2001). Raphael Wiist (former PhD student at UBC) performed the peat sampling. Michelle Hawke performed all organic petrographic analyses and data compilation. Interpretation and subsequent writing was performed by both Wiist and Hawke in a collaborative fashion, with each contributing equally to the final manuscript. References: Wiist, R.A.J., Hawke, M.I., and Bustin, R.M. 2001. Comparing maceral ratios from tropical peatlands with assumptions from coal studies: do classic coal petrographic interpretation methods have to be discarded? International Journal of Coal Geology, 48:115-132. Acknowledgements I am indebted to numerous people for their support in the completion of this thesis. / University of British Columbia My supervisor, Dr. R. Marc Bustin at the University of British Columbia has provided both the financial support and professional guidance that has made the completion of this work possible. My collegue and friend, Dr. Raphael Wiist, currently at James Cook University in Australia, provided both encouragement and advice during the completion of the thesis and a thorough review of a draft of the completed project. Bert Mueller helped to develop a lab protocol for the sequential leaching procedure through numerous lengthy discussions and provided training and advice for the operation of the ICP-MS. Tammy Cohen, Doctoral Candidate from the Biology Department performed much of the ICP-MS analysis for the second batch of sequential leaching in an efficient and expert manner. Dr. Kristin Orians generously allowed me to use her laboratory facilities to complete the first batch of sequential leaching work while I was in Vancouver. Calgary I am particularly grateful to Dr. Fariborz Goodarzi at the Geological Survey of Canada-Calgary for all the professional, scientific, financial and personal support that he provided during the course of this project. The GSC-C/Teck-Cominco Trail smelter project was developed under his leadership, and it was he who provided the original suggestion of a peat project in Trail. This research was conducted in concert with several other GSC-Calgary studies at the Trail smelter, and this body of research, to which I was allowed access, was invaluable in providing supporting evidence for my own research. Many thanks are due to the other scientific researchers and technical support personel involved in the Trail smelter project. Hamed Sanei, Doctoral Candidate at the University of Victoria and member of the Enviromental Research Group at GSC-C is thanked for his helpful discussions and reviews of earlier drafts of this thesis. Julito Reyes of the GSC-C is thanked for all his help in obtaining data, advice and helpful discussions. Marcel Labonte is thanked for his many helpful suggestions regarding geochemistry and data handling. Sharlene Pollock is gratefully acknowledged for years of scientific discussions on the topics of peat, coal and elemental analysis, her supportive friendship throughout years of change, and for reading an ugly first draft of the thesis. Additionally, I am very thankful for the support of numerous other people at the GSC-C. Dr. Lavern Stasiuk permitted me to use the organic petrography laboratory facilities and is thanked for his many helpful discussions and reviews of early drafts. Jenny Wong is thanked for her help with the SEM-EDX and the XRD. Kathleen Bradford is thanked for her assistance with the carbon and sulphur analysis, and for years of supportive friendship in the lab and the office. Bill Duncan of Teck-Cominco provided me with background information regarding the smelter operation and the Trail area, and permitted me to access sites within the smelter property. Don Espahain, Mariah Duncan and Brandee Venne provided their assistance with the peat sampling. I would like to acknowledge my friends and collegues in the Coalbed Methane group at Suncor Energy for their support, encouragement and understanding while I completed my thesis. In particular, I would like to acknowledge my former manager Mike Dawson, currently of Defiant Energy, who permitted me to work the flexible schedule that made it possible for me to finish my thesis while learning the mysteries of CBM, and Kim Russell-Symon and Louise Huston, whose words of encouragment were greatly appreciated. Finally, I would like to thank my partner Ryan Gaetz for years of unfailing, encouragement and patience, and for always having faith in me. Chapter 1 Introduction 1.1 Monitoring of Anthropogenic Trace Elements The monitoring of trace elemental emissions has become an essential aspect of many industrial operations. Concerns about aerially dispersed materials such as fly ash and the contaminants contained within them have prompted industries to control emissions and to monitor their impact on the surrounding environment. However, monitoring the impact of anthropogenic activities is a complicated process. Assessments of trace metal fluxes based on mass balance equations (e.g. Nriagu and Pacyna, 1988) have come under criticism (e.g. Rasmussen, 1996) because they often do not account for geogenic (naturally occurring) trace metals, and because the models are often based on inaccurate data. Trace element partitioning in the environment following deposition is poorly understood, and determination of the dispersal patterns of elements requires that the methodology employed captures all the phases of pollution that are of concern (Rasmussen, 1996). Hence, it is necessary to employ a variety of monitoring methods and types of sampling media to accurately characterise the distribution of trace elements around a point source. 1.2 Peatlands as a Sink for Trace Elements Peat deposition and early diagenesis are controlled by many factors that interact to lead to the formation of peats which are relatively unique products of their environment. The geochemical characteristics of a peat deposit are a function of the surrounding country rock, hydrology, climate and the depositional environment (e.g. Goodarzi, 1995). In anthropogenically altered environments, both airborne and waterborne trace elements can become deposited within the peat. Pollutants from the atmosphere are deposited in the peat via wet deposition as ions in precipitation, or dry deposition as particulate matter (Godbeer and Swaine, 1995). Minerotrophic peatlands, which are fed by groundwater, are subject to the input of elements carried in solution by groundwater from the surrounding area. Organic matter is capable of complexing and chelating many trace elements which are of environmental concern, particularly under low pH reducing conditions (Forstner, 1987), and so may remove much of the potentially hazardous material from groundwater. For this reason, peatlands may act as a sink for many elements, and may have elemental concentrations that are elevated relative to the surrounding area. A study examining the concentration and mode of occurrence of trace elements within peatlands surrounding a point source of pollution offers the opportunity to better understand the role of peatlands in sequestering trace elements. 1.3 The Teck-Cominco Trail Smelter The location of this study is Trail, British Columbia, which is situated in the Columbia River valley. A smelter has been in operation in Trail since 1896, originally to process copper ores mined in nearby Rossland. Over the years, the smelter has expanded and is currently one of the largest facilities of its kind in the world (Fig. 1-1). Production totals from the year 2000 are listed by Teck-Cominco as 272 900 tonnes of Zn, 91 300 tonnes of Pb, 12 212 000 ounces of Ag and 56 000 ounces of Au (Teck-Cominco, 2003). Previously, the main source of the ore concentrate was the Sulivan Pb-Zn mine in Kimberly, BC, which was in operation for 92 years, from 1909 until its closure in 2001. The main source of concentrate is currently the Red Dog mine in Alaska, which has been in operation since 1989 and is the largest Zn mine in the world. Emmissions of Pb from the smelter stack have reportedly been reduced dramatically by the installation of a KTVCET Pb smelter in 1997 (Teck-Cominco, 2000). Lead emissions from the stack are reported by Teck-Cominco to be 268 kg/day in 1995, but were reduced to 85 kg/day in 1999. The new smelter also resulted in the reduction of Cd (from 13 to 1.7 kg/day) and As (from 41 to 5.5 kg/day) stack emissions between 1995 and 1999. Zinc stack emissions increased during this time, however, from 383 to 412 kg/day. Particulate matter contents measured in ambient air in the Trail area were not appreciably reduced by the installation of the new Pb smelter, despite the reduction in stack emissions. Teck-Cominco attributes this observation to the fact that sources such as fugitive dust from unprocessed ore concentrates and geogenic dust are also major contributors to the particulate composition of the air. 1.4 Objectives The objective of this study is to examine the trace element content of organic soils and peats in the vicinity of a Pb-Zn smelter using a variety of analytical techniques. This program was carried out in order to achieve several goals: Figure. 1-1. Trail, British Columbia, in 1904 (a), 1944 (b) and 2000. Photos a and b were obtained from the City of Trail Archives (2003). -to assess the extent of trace element contamination in the area surrounding the smelter -to determine if trace elements deposited from the smelter are mobile in the environment, thus suggesting greater bioavailability and therefore a greater threat to health, and further indicating the need for environmental trace elemental monitoring programs that account for potential post-depositional migration -to determine the relative importance of peats and organic soils as sinks for mobile trace elements relative to mineral soils; -to determine if it is possible to identify the source of the trace elements using some commonly-used geochemical fingerprinting methods, such as rare earth element patterns and normalisation to conservative elements; -to examine the morphology and chemistry of particulate material containing trace elements found within the peat, and to compare the results to those from fresh smelter feedstock, baghouse wastes and particulates captured by moss monitoring stations, in order to assess the source and the influence of weathering on the particulate material; -to determine the mode of occurrence of trace elements as a function of distance from the smelter, peat depth and trace element source; -to evaluate the organic petrographic characteristics of the peats in the context of the mode of trace element occurrence, in order to determine how the early diagenetic conditions within the peat influence trace elemental behaviour. 1.5 Chapter Outline In order to accomplish these goals, the project was divided into a series of five phases of experimental work. Each of these phases is written up as a separate paper for publication in a refereed journal, and is presented as an individual chapter in this thesis. A brief description of each chapter is as follows: Four peatlands located within a 16-km radius of the smelter were identified and sampled. The total concentrations of trace elements in peats from profiles at the margin and in the centre of the peat deposit were compared to trace element concentrations in nearby mineral topsoils and to rates of atmospheric deposition as determined by a moss monitoring program (Goodarzi et al., 2001; 2003). The results of this project are discussed in Chapter 2. Two methods of geochemical fingerprinting were applied to the peat and soil data in order to determine their usefulness in distinguishing between sources of elemental input. The first method used was the normalisation of trace element concentrations to concentrations of a supposed conservative geogenic element, such as Ti or Zr. The data used for normalisation was derived from numerous sources, including published geochemical data for the region and local soil data. The second method was to compare REE concentrations and chondrite-normalised REE patterns from peats, mineral soils, moss monitoring stations, stream sediments and smelter feedstocks and wastes, in order to determine if the impact of the smelter can be discerned from REE signatures. The results from this phase of the project are presented in Chapter 3. Ash (combustion residue) from selected peat samples was examined by scanning electron microscopy (SEM) and the elemental composition of individual particles was determined by Energy Dispersive X-Ray spectroscopy. Particle morphology and chemistry are both a function of source. Stack emissions are typically rounded as a result of heating and subsequent rapid cooling, and are most commonly oxides. Fugitive dust particles from unprocessed ore concentrates are angular and are mainly sulphides. Geogenic particles derived from the bedrock are typically angular and have chemistry consistent with the local mineralogy. Using this combined morphology-chemistry approach, the distribution of trace element-containing particles can be determined as a function of peat depth and distance from source. The results of this investigation are presented in Chapter 4. Selected peat, mineral soil and stream sediment samples were sequentially leached in order to determine the mode of occurrence of trace elements. The sequential leaching procedure used in this experiment is selective for exchangeable, carbonate, reducible Fe-Mn, organically-chelated, organic/sulphide and residual phases. The mode of occurrence varies as a function of the trace element source, and of the conditions within the sediment. The results of this study are presented in Chapter 5. The organic petrography of the peats was examined under reflected white and blue light. Organic petrographic characteristics such as the extent of humification and oxidation, and the presence of fungal remains are indicators of the early diagenetic conditions within the peatland, which in turn are a partial control on the mode of occurrence of trace elements. Results of the organic petrographic study are presented in Chapter 6. 1.6 Other Research-Organic Petrography of Tasek Bera, Malaysia In addition to the Trail smelter study, the author was involved in an investigation of the organic petrographic characteristics of a series of peats from Tasek Bera, Malaysia. The purpose of this study was two-fold: 1. to characterise the organic petrography of peat profiles sampled from known depositional environments in order to construct a history of vegetational and early diagenetic conditions within peatland and 2. to apply the concept of using ratios of \"index macerals\" to determine if these maceral ratios can differentiate between different peat depositional environments. This concept has been used extensively for coals, but little evidence of its validity exists from peat organic petrography studies. The results of this study are presented in Appendix A, and were published as Wiist et al., 2001. The organic petrographic study presented in Chapter 6 builds on concepts developed during the course of this work. 1.7 References City of Trail, 2003. Museum and Archives. Available: http://www.cityoftrail.com/ourcity/museum.htm Forstner, U., 1987. Metal speciation in solid wastes\u00E2\u0080\u0094Factors affecting mobility. In: Speciation of Metals in Water, Sediment and Soil Systems, L. Landner, ed. Lecture Notes in Earth Sciences, Springer Verlag, pp 13-42. Godbeer, W.C. and Swaine, D.J., 1995. The deposition of trace elements in the env irons of a power station. In: Environmental Aspects of Trace Elements in Coal, D J. Swaine and F. Goodarzi, eds., Kluwer Academic Publishers, Dordrecht, pp 178-203. Goodarzi, F., 1995. Geology of trace elements in coal. In: Environmental Aspects of Trace Elements in Coal, D.J. Swaine and F. Goodarzi, eds., Kluwer Academic Publishers, Dordrecht, pp 51-75. Goodarzi, F., Sanei, H. and Duncan, W.F., 2001. Monitoring the distribution and deposition of trace elements associated with a zinc-lead smelter in the Trail area, British Columbia, Canada. Journal of Environmental Monitoring, 3: 515-525 Goodarzi, F., Sanei, H. and Duncan, W.F., 2003. Deposition of trace elements in the Trail region, British Columbia; an assessment of the environmental effect of a base metal smelter on land. Geological Survey of Canada Bulletin 573, 50 pp. Nriagu, J.O. and Pacyna, J.M., 1988. Quantitative assessment of worldwide contamination of air, water and soils by trace metals. Nature, 333: 134-139. Rasmussen, P.E., 1996. Trace Metals in the Environment: A Geological Perspective., Geological Survey of Canada Bulletin 429, 26 p. Teck-Cominco, 2000. Environmental Performance Review of the New KIVCET Lead Smelter and Refineries Abatement Upgrades: Air Emissions and Ambient Air Quality available: http://www.teckcominco.com/articles/operations/tr-kivcet-envperfrev.htm Teck-Cominco, 2000. Trail Smelter and Refineries Production available: http://www.teckcominco.com/operations/trail/production.htm Wiist, R.A.J., Hawke, M.I. and Bustin, R.M., 2001. Comparing maceral ratios from tropical peatlands with assumptions from coal studies: do classic coal petrographic interpretation methods have to be discarded? International Journal of Coal Geology, 48: 115-132. Chapter 2 Trace elements in organic deposits in the area surrounding a base metal smelter 2.1 Introduction The capacity for organic sediments to sequester and retain metals has long been recognised and a number of studies have examined peatlands as sinks for atmospheric and groundwater contaminants in areas of elevated pollution (e.g. Mathews and Bustin, 1994; Gorres and Frenzel, 1997; West et al., 1997). A study of the trace elemental distribution in peatlands in the vicinity of point sources of trace element emissions, combined with an atmospheric deposition monitoring program, offers an opportunity to examine the role of organic deposits in sequestering geogenic and anthropogenic trace elements. This paper discusses the concentration of selected trace elements measured in peats and soils in the vicinity of a lead-zinc smelter. 2.1.1 The Inorganic Geochemistry of Peatlands The geochemical characteristics of a peat or coal deposit are dependent upon the surrounding geology, hydrology, climate and depositional environment (e.g. Goodarzi, 1995). Minerotrophic peatlands (peatlands which are hydrologically connected to the regional groundwater table) sequester and concentrate elements carried in solution by groundwater from the surrounding bedrock. Organic matter is capable of complexing and chelating numerous trace elements which are of environmental concern, particularly under reducing conditions, such as are found in peatlands (Forstner, 1987). Organic deposits can therefore act as a geochemical sieve and remove potentially hazardous material from groundwater. Trace elements may also be adsorbed onto clays and iron and manganese oxides, hydroxides and oxy-hydroxides, or form epigenetic minerals such as sulphides (e.g. Allard, et al., 1987; Elder, 1988; Clark et al., 1998; Bendell-Young, 1999). For this reason, peatlands may act as a sink for many elements, and may have concentrations that are elevated relative to the surrounding area. 2.1.2 Atmospheric trace element deposition and the mobility of trace elements within the peat profile Airborne pollutants may be deposited in peat via wet deposition as ions in precipitation or via dry deposition as particulate matter (Godbeer and Swaine, 1995; Goodarzi et al., 2001). Peat profiles have been shown to act as repositories of atmospherically deposited trace elements. For example, the trace element chemistry of peat cores from the Jura region of Switzerland can be correlated with anthropogenic events such as Roman lead-smelting and the use of leaded gasoline (Shotyk, 1995; 1996; Shotyk et al., 1996; 1997). Similar studies have been conducted by a number of other researchers (e.g. Gorres and Frenzel, 1997; West et al., 1997, Espi et al., 1997; Schell et al., 1997; Steinnes, 1997; Gilberston et al., 1997; Kempter et al., 1997; Kiister and Rehfuess, 1997; Martinez Cortizas, 1997; Weiss et al., 1997). While Shotyk et al. (1997) indicate that minerotrophic peats are not suitable for chronostratigraphic trace element studies due to geogenic overprinting, attempts have been made to discern anthropogenically-sourced elements from geogenic inputs through the use of enrichment ratios, often normalised to crustal abundance ratios. Once deposited on the surface and incorporated into the peat, it is likely that some of the elements will be mobilized and redistributed further. Elements may be mobilized as a result of the prevailing conditions within the peatland such as pH, redox potential, the presence of complexing ligands and adsorption sites, and the presence of soluble organic colloids with which the metal can form a mobile colloidal species (e.g. Honeyman, 1999; Kersting, 1999). Trace nutrients (e.g. Cu, Zn, Mo), and other elements subject to uptake by plants (e.g. Cd), may be enriched in the surficial peat as a result of biogeochemical cycling (Trudinger et al., 1979; Rasmussen, 1996; Espi et al., 1997). Due to the large potential for post-depositional migration, trace element concentrations in the peat profiles were not assumed to be chronostratigraphic. 2.2 Study Area Trail, British Columbia (Fig. 2-1) is situated in the Columbia River Valley, which bisects the sampling area. The Columbia River is the boundary between the Monashee (west side) and Selkirk (east side) Mountains. The bedrock in the area consists mainly of Upper Jurassic plutonic rocks (the Nelson Intrusives), and Lower Jurassic metavolcanic and metasedimentary rocks (the Elise Formation; Little, 1982; Hoy and Andrew; 1991). The surficial geology is influenced by Pleistocene glaciation, and the area is predominantly covered by discontinuous ground moraines (Little, 1982). The Teck-Cominco Trail smelter has been in operation since 1896. Lead-zinc ores are the major product processed, but the plant also processes Ag, Au, Cd, Bi, In, Ge concentrate, Ge02, CUSO4, CuAsO, sodium antimonate and sulphur products (Henderson et al., 1999). Environmental conditions in the area surrounding the smelter have improved in recent decades with the adoption of better production and containment technologies, and ore handling and storage practices, although Ag, As, Cd, Cu, Hg, Pb and Zn are known to be emitted by the facility (Henderson et al., 1999). Site Bedrock Geology Vegetation pH and Comments Cominco UTM Zone 11, 0446226, 5440375 Trail Pluton (granodiorite, quartz diorite) Typha latifolia (common cattail), Epilobium ciliatum (purple leafed willow herb) Carex urticulata (beaked sedge) Equisetum palustre, and Deschampsia cespitosa (tufted hairgrass) 5.3 (surface) 5.6 (mineral sediment) 5.7 (pore water) -saturated at the time of sampling, although gleying was noted in the uppermost 15 cm-intermittently aerobic. Zones of oxidation were noted around roots. Thunder Road UTM Zone 11, 0445145, 5440974 Trail Pluton (granodiorite, quartz diorite) Typha latifolia (common cattail), Pinus sp. (pine) Betula sp. (birch) Epilobium ciliatium Equisetum palustre, and Deschampsia cespitosa (tufted hairgrass) 5.0 (surface) 5.4 (mineral sediment) 5.7 (pore water) -watertable was approximately 10 cm below the surface at the time of sampling Champion Lakes Provincial Park UTM Zone 11, 0453623, 5448726 Elise Formation (flow breccia, lava agglomerate, volcanic breccia, tuff, tuffaceous conglomerate, andesite, basalt, augite porphyry, metamorphosed to greenschist facies) Limestone xenoliths and calcite amygdules found within mafic flows. Economic deposits of Pb, Zn, Ag, associated with sulphides. Carex sp. Nuphar lutea (cow lily) Assorted grasses 6.5 (surface) 6.5 (15cm depth) 6.4 (pore water) Saturated profile Bombi Summit UTM Zone 11, 0459296, 5454509 Bonnington Pluton (hornblende rich granodiorite, granitic gneiss, amphibolite) Carex sp. Assorted grasses . Organic rich-sediment, not peat Possible urban contamination, due to proximity to road Table 2-1. Location, bedrock geology, vegetation and general notes on the sampling locations. Details of bedrock geology are from Little, 1982; Hoy and Andrew, 1991. 117\u00C2\u00B046' 117*34' ,49*15* QUATERNARY \u00E2\u0080\u00A2Unconsolidated sediments; till, sand gravel, silt JURASSIC/CRETACEOUS HNELSON INTRUSIONS: granodiorite; mhor quartz diorite and diorite SROSSLAND MONZONITE: biotite-hombtende-augite monzonitB, mainly medium grained JURASSIC I \u00E2\u0080\u0094 E U S E FORMATION: < flow breccia, massive andesites L , I and basalts, agglomerate, tuff, breccia, laminated siltstone MOUNT ROBERTS FORMATION: I - \u00E2\u0080\u0094 y *lblack siltstone and argillaceous pHdquartzite, slate, greywacke, chert pebble conglomerate, lava; Imestone AGE UNKNOWN TRAIL GNEISS: amphibolite and grey biotite gneiss, hornblende gneiss, mica schist, aplcte and pegmatite Figure 2-1. Geology of the Trail area and the location of the smelter and sampling sites. After Little, (1982). Sampling locations are described in Table 2-1 and are indicated on Figure 2-1. The sites consist of small, shallow, high ash minerotrophic peatlands. The climate of the area is dry and not conducive to the formation of large peatlands, and so peat-forming environments are small and isolated. The Cominco site is a small wetland (approximatley 0.5 km 2 ) located in the Columbia River Valley which is subject to the input of metals from several sources: emissions directly from the smelter approximately 0.5 km away, from fugitive dust containing Pb-Zn ore concentrates that circulates through the valley in the smelter area (e.g. Goodarzi et al., 2001; 2003) and from secondary sources such as road dust. The Thunder Road, Champion Lakes and Bombi Summit sites are wetlands located 1.6, 13.5 and 16 km from the smelter, respectively. In terms of topography, these three sites are sheltered to varying degrees from the smelter\u00E2\u0080\u0094the Thunder Road site is located above the river valley and is partially sheltered by a ridge of rock, while the Champion Lakes and Bombi Summit sites are located in the mountainous terrain east of the valley. Secondary sources may affect each of the locations. The Thunder Road site may be subject to input from the Teck-Cominco fertiliser factory (Fig. 2-1), and is also located near an unmanaged automobile dumping site. The Champion Lakes sites are located in a provincial park and may be subject to minor input stemming from recreational activities such as vehicle traffic. The Bombi Summit site is located near a major roadway. In a geologically diverse environment such as the study area, it is difficult to establish meaningful background elemental concentrations. Published bedrock geochemical data for the region (Table 2-2) indicates a high degree of heterogeneity between the Elise Formation and the Nelson Intrusives, and between rock types within each formation. The area hosts numerous ore deposits, which were actively mined until the mid-20th century, and zones of trace element enrichment are naturally present within the bedrock. Hence, anthropogenic impact can not be calculated based on a comparison to a single set of established background values. Therefore, data from the peat was compared to trace element concentrations in mineral soils and to atmospheric trace element deposition rates (Goodarzi et al., 2001; 2002; 2003) in order to better discriminate between anthropogenic and geogenic sources of trace elements, and to illustrate the role of organic sediments in the distribution of trace elements in an area subject to a point source of anthropogenic impact. Nelson Intrusives Elise Formation % Granodiorite Quartz Gabbro K-Tonalite Granodiorite Ankaramite Basalt K-Andesite Si02 Ti02 Al 203 Fe203 MnO MgO CaO Na20 K 2 0 P2O5 64.2 0.6 16 4.9 0.1 2.0 4.8 3.5 3.1 0.2 54.2 0.9 17.4 9.7 0.2 4.2 7.0 4.0 1.8 0.3 60.5 0.6 16.9 6.4 0.1 2.4 4.8 4.7 2.9 0.3 66.0 0.4 16.5 3.7 0.1 1.1 4.0 4.1 3.4 0.2 48.1 0.8 12.2 12.9 0.2 12.4 9.4 2.0 1.6 0.3 51.3 0.9 14.5 11.6 0.2 6.4 9.4 3.1 1.8 0.3 55.4 0.8 15.1 9.4 0.1 4.1 7.8 3.8 2.8 0.3 ppm V Cr Ni Zn Ga Rb Sr Y Zr Nb Ba Pb Th Cu 100 20 5 69 18 93 654 18 130 16 1039 13 9 223 32 13 126 21 72 744 20 65 8 809 9 5 130 22 7 82 19 96 700 21 122 12 1057 9 6 59 10 5 54 17 102 782 14 107 13 1418 12 6 264.3 664.2 212.2 97.2 39.2 541.5 14.5 61.8 2.8 588.2 118.2 314.5 125.8 39.8 97.2 38.0 755.8 18.5 89.5 3.8 685.0 63.8 222.8 26.5 6.8 90.5 52.2 889.5 17.2 114.8 4.2 939.2 37.8 Table 2-2. Compilation of published geochemistry for the bedrock underlying the peat sampling sites. Data for the Nelson Intrusives is presented as published in Sevigny (1990). Data for the Elise Formation is presented as published in Beddoe-Stephens and Lambert (1981). 2.3 Methodology 2.3.1 Peat Sampling and Analytical Protocol Sampling sites were selected to encompass a range of anthropogenic impact levels. For each site, general observations were made about the hydrology, vegetation, topography and proximity to sources of inorganic inputs. Blocks of peat were removed from the ground by digging a pit with a steel shovel and cutting block samples from the pit wall with a stainless steel knife. The samples were bagged in sealable freezer bags and were refrigerated at 4\u00C2\u00B0C within 24 hours of sampling. Locations were sampled twice, in September, 1998, and in September, 2000. The first time, the peat was sampled from near the margin of the peatland, while samples were taken from the centre of the peatland in the second sampling period, in order to determine lateral variation. There are two separate sampling locations for the Champion Lakes site. The material from the first sampling session consisted of a shallow (16 cm) high ash lacustrine peat from First Lake. Since this peatland consisted of a narrow organic deposit at the lake margin, it was not possible to sample profiles representative of the margin and the interior at this specific location. The second sampling site from the interior of a wider, deeper lacustrine peat (> 1 m), sampled from Second Lake (Fig. 2-1). The Bombi Summit sampling site consists of a thin margin of organic soil surrounding a pond. The extent of the organic soils at this site was too small to obtain samples representative of the interior of a peatland, and the results presented here are representative of a margin environment. The samples were split in the following manner: Surficial peat (0-8 cm) was sectioned at 1 cm intervals. Peat below this level was sectioned at 3 cm intervals. Subsampling was performed wearing vinyl gloves, using a plastic knife, on a freshly plastic-covered lab bench in a clean room. The samples were air dried on plastic plates, covered loosely by plastic sheeting. To facilitate final air drying, the peat samples were placed in a warm (30\u00C2\u00B0C) oven overnight. A sample for elemental analysis was removed from the middle of each peat slice, reducing the possibility of analysing material that was contaminated during the sampling procedure. All elemental analysis for the first sampling period was performed by Becquerel Laboratories, Mississagua, Ontario, Canada, using Instrumental Neutron Activation Analysis (INAA) (As), and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) (Cd, Cu, Pb, Ni, and Zn). Zinc concentrations were obtained using both methodologies, and the results were consistent between methods, although ICP-MS results are reported here. Analytical precision is variable between elements and is dependent upon concentration and the detection limit. The relative standard deviations for INAA analysis, as calculated with NIST standard 1633, are as follows: As: 3.1% and Zn: 9.6%. The peat was not fractionated in any way prior to analysis, as the desired results were for the bulk sample. Element concentrations for the second sampling period were determined by ICP-MS following microwave-assisted dissolution in 20 ml HNO3-HF-HCI solution (5:4:1), in accordance with the recommended procedure supplied by the manufacturer (CEM, personal communication, 2001). Due to the highly volatile nature of the organic-rich samples, it was necessary to perform a pre-digestion step in the acid solution, first at room temperature in open vessels, followed by a period of gentle heating on a hotplate, until a visual inspection revealed that the organic matter had been decomposed. The microwave heating procedure was repeated until the sample was completely dissolved; the number of repetitions depended on the solubility of the sample. Average errors, as determined by replicate analyses, were as follows: Sb: 11.3%, As, 13.3%, Cd: 8.9%; Cu: 11.7%; Ni: 6.7%, Pb, 11.5%; Zn: 7.3%. 2.3.2 Soil Sampling Mineral topsoils were sampled using a 5 cm diameter probe. Two samples were taken from each site unless otherwise specified: a surface sample consisting of vegetation and the topmost 3 cm of soil, and a 3-10 cm depth core. The samples were wrapped in separate plastic bags and stored in a freezer until analysis. Soils were homogenized and analysed for elemental content using INAA and ICP-MS (Becquerel Laboratories) as described for the peats. In order to evaluate the extent of metal partitioning between peats and mineral soils, a ratio of the trace element concentration in the peat versus the concentration in the nearest sampled mineral soil was calculated. Theoretically, geogenic elements are likely to be concentrated in the soil relative to the peat, while atmospherically introduced elements may be present in equal or greater amounts in the peat, due to organic/anaerobic sequestration of mobile species. McMartin et al. (1999) conducted a study of the vertical distribution of trace metals in soil profiles surrounding a lead-zinc smelter, and found that significant migration occurs, particularly in soils that are very close to the smelter. For the purpose of comparison, soil from 0-3 cm depth was used to calculate the enrichment factor for peats of the same depth interval, while soil from the 3-10 cm interval was used for peats greater than 3 cm in depth. Factors of enrichment in the peat relative to the mineral soil were calculated as follows: Peat Enrichment Factor (PEF) = [ M e ] P e a t / [ M e ] s o i i [Me]peat = the concentration of the trace element in the peat [ M e ] S O i i = the concentration of the trace element in the mineral soil 2.3.3 Moss Monitoring Rates of Aerial Deposition A network of moss monitoring stations was set up as part of the Geological Survey of Canada atmospheric trace element deposition impact study in the vicinity of the Trail smelter, British Columbia (Goodarzi et al., 2001; 2002; 2003; Fig. 2-1). The moss monitoring project is modeled, with some modification, after the methodology developed by Martin and Coughtrey (1982) and Swaine et al., (1983) and is described fully in Goodarzi et al. (2001; 2003). In brief, the moss monitoring project involves a network of \"moss traps\", located throughout the Trail area, which consist of acid-washed Sphagnum moss inserted into a flat acid washed nylon mesh bag, which is suspended in a frame on top of a 2 m pole. After three months of exposure, the moss bags are collected, and the elemental concentrations in the moss are measured by INAA and ICP-MS (Becquerel Laboratories, Mississagua, ON). As the mass of the moss, the area of the moss trap and the length of exposure are known factors, the rate of elemental deposition at the moss monitoring station can then be calculated as g/ha/3 months. 2.4 Results 2.4.1 Trace Element Concentrations in the Peats The highest concentrations of Sb, As, Cu, Pb, Ni, and Zn are found in the Cominco profile, 0.5 km from the smelter (Table 2-3). Concentrations of trace elements are typically lower in the Thunder Road profile, although very high Cd concentrations were measured in the samples from the margin of the peatland. Trace element concentrations are considerably lower in the Champion Lakes and Bombi Summit profiles. A plot of average trace element concentrations versus radial distance from the smelter illustrates a rapid decrease in concentrations with increasing distance (Fig. 2-2). In order to provide a basis for comparison, the trace elemental concentrations for a background site underlain by the Trail Pluton, and soil quality guidelines provided by the British Columbia Ministry of Water, Land and Air Protection (2002) and Environment Canada (2002) are listed in Table 2-3. 2.4.1.1 Cominco Site The peat from the Cominco site has elevated concentrations of Sb, As, Cd, Cu, Pb and Zn relative to British Columbia (2002) and Canadian (2002) environmental quality standards for soils (Table 2-3; Fig. 2-3). Of particular significance are concentrations of Pb of up to 5240 ppm and Zn concentrations of up to 5910 ppm. Concentrations are variable both with peat depth and with distance from the margin of the peatland. Concentrations of Cd, Pb and Zn are higher in the surface peat from the margin than in the surface peat from the centre of the peatland, while As concentrations are higher in the surface peat from the peatland centre, and concentrations of Sb, Cu and Ni are approximately the same at both locations. Concentrations of elements in the peat from the profile bases are higher in the peat sampled from the margin for all elements examined with the exception of Ni (Fig. 2-3). In the Cominco peat margin profile, the concentrations of Sb and Zn are highest at the surface and decrease with depth, while As and Pb are most concentrated at the base of the profile and Cd, Cu and Ni concentrations are consistent throughout (Fig. 2-3). In the profile from the centre of the peatland, the concentrations of elements are consistent in the top 7 cm, decline from 8-11 cm, and are highly enriched in the 14-17 cm sample. The 14-17 cm sample corresponds to the macroscopically-observed transition between the aerobic and anaerobic zone, based on the presence of iron oxide nodules in the shallow peat and gleying (reduced iron) at depth (Table 2-1). It is hypothesised that this zone of enrichment occurs as a result of the transition from oxidising to reducing conditions with depth. Mobile species become sequestered under the anaerobic conditions, possibly as sulphides. Elements adsorbed to or coprecipitated with Fe/Mn oxides may become soluble during periods when the watertable is high and reducing conditions prevail at shallower depths in the profile, and may be subsequently reprecipitated in a zone of enrichment when oxidising conditions return. Below this zone of enrichment, element concentrations decrease with depth to a minimum in the peat above the contact with the mineral sediment. The only element that does not behave in this manner is Ni, for which concentrations vary little with depth or laterally (8.3 - 13.5 ppm in the peat from the centre of the peatland, and 10.8-15.4 ppm in the peat from the margin). Nickel concentrations do not exceed the listed soil quality standards. All trace elements, with the exception of Ni, are enriched in the peat relative to the mineral soil (Table 2-4), with PEFs of up to 31 times for Sb, 20 times for As and 15 times for Pb in selected samples. Nickel PEFs are approximately lor lower throughout the profiles, indicating a lack of preferential sequestration in the peat. The basal mineral sediment is enriched relative to the mineral soil in Sb, As Cu and Pb, but depleted in Zn, and is approximately at unity for Cd and Ni. Sample Sb As Cd Cu Pb Ni Zn Depth (cm) ppm ppm ppm ppm ppm ppm ppm CO MINCO MARGIN 0-1 126 78.5 61.7 196 3550 10.8 5910 1-2 141 97.8 65.2 223 3830 11.6 5600 2-3 128 153 53.8 215 3780 15.4 4230 3-4 142 116 60.3 227 3830 13.2 4730 4-5 121 164 47.1 214 3940 14.8 3570 17-20 85.0 247 60.1 226 5240 12.4 3040 COMINCO INTERIOR 2-3 111 152 31.5 160 2609 10.4 3430 3-4 130 148 36.9 184 2698 12.2 3938 7-8 112 159 32.9 166 2758 12.8 3280 8-11 79.5 136 4.8 80.4 1600 12.2 586.7 14-17 450 380 30.3 504 3447 10.8 17 77 20-23 145 265 7.9 122 2097 13.5 1105 32-36 11.3 7.0 1.8 26.0 264.4 8.3 212.9 Basal Sediment 32.1 75.7 4.5 94.0 933.3 8.6 390.3 THUNDER ROAD MARGIN 0-1 34.1 60.0 119 82.0 1670 9.2 2730 1-2 37.7 64.4 105 103 2070 10.6 2270 2-3 33.0 62.0 139 84.0 1750 9.4 2900 3-4 37.6 65.4 134 96.0 1980 11.0 2590 5-6 32.5 67.5 104 92.0 1990 10.8 2330 11-14 34.9 59.0 120 96.0 1940 11.0 2300 THUNDER ROAD INTERIOR 0-1 19.5 50.2 27.5 43.1 580.2 8.0 2204 2-3 22.4 52.4 24.8 74.1 536.9 13.3 1942 3-4 25.3 50.4 20.2 92.0 455.2 12.4 1467 5-6 28.3 42.7 24.5 152 613.5 15.1 1570 14-15 18.0 28.3 9.2 142 428.7 16.4 809.2 19-20 10.7 10.7 3.3 353 193.4 15.0 358.3 Basal Sediment 8.0 11.7 1.0 14.9 144.0 13.3 161.7 CHAMPION LAKES MARGIN 0-1 1.2 1.8 2.4 12.0 77.0 3.0 148 1-2 1.6 3.6 3.7 16.0 102 6.0 194 2-3 5.5 8.3 6.0 14.0 172 9.2 214 3-4 3.8 6.8 4.4 13.0 115 6.0 208 4-5 9.0 15.4 6.8 20.0 246 8.8 268 11-16 15.2 15.8 6.5 24.0 324 4.4 178 CHAMPION LAKES INTERIOR 2-5 5.0 7.0 3.3 10.7 79.5 4.6 211.1 14-15 10.6 9.5 3.5 28.3 110.4 8.8 137.4 22-26 2.9 4.0 3.2 28.5 4.1 8.2 45.9 35-36 1.4 2.6 1.0 30.6 1.5 12.3 24.2 49-50 0.8 2.1 1.3 31.0 0.0 12.6 22.6 63-64 0.9 5.3 0.6 21.4 0.0 10.7 50.2 79-80 0.6 1.8 0.6 18.1 0.2 11.1 37.2 Sample Depth (cm) Sb ppm As ppm Cd ppm Cu ppm Pb ppm Ni ppm Zn ppm BOMBI SU MMIT 0-1 2.2 2.9 2.1 14 79.5 12.8 130 1-2 3.0 7.8 2.1 15 104 10.2 122 2-3 2.8 22.6 2.1 13 109 11.2 116 3-4 5.0 7.8 3.3 18 191 11.4 150 4-5 8.8 9.8 7.9 29 476 10.8 248 6-7.5 3.5 2.4 0.3 7.4 61.7 8.8 66.3 7.5-9 1.3 5.2 0.8 6 35 12.4 76.0 MINERAL SOILS Station and Sb As Cd Cu Pb Ni Zn Depth (cm) ppm ppm ppm ppm ppm ppm ppm Cominco 0-3 42.8 45.9 38.0 107 .1215 13.4 4140 Cominco 3-10 14.3 18.7 6.2 31.2 343 12.8 836 Thunder 0-3 5.2 8.9 1.3 25.4 165 14.6 184 Thunder 3-10 3.4 6.1 0.9 25.2 101 14.0 138 Champion 0-3 2.2 8.5 1.1 31.2 55.5 17.2 218 Champion 3-10 1.9 10.3 0.8 31.8 37.0 17.8 142 Castlegar 0-3 2.6 7.2 1.4 22 68 32 112 Castlegar 3-10 3.2 7.9 0.9 20 61 26 132 Background 0-3 0.9 2.7 0.2 11.6 31.8 25.0 76.0 B.C. REMEDIATION STANDARDS FOR SOILS reloc. non-ag. Disp. auth. req. 20 15 1.5 90 100 100 150 40 15 1.5 90 100 500 150 ENVIRONMENT CANADA SOIL ENVIRONMENTAL QUALITY GUIDELINES Agricultural Residential/Park Industrial 20 12 1.4 63 70 50 200 20 12 10 63 140 50 200 40 12 22 91 600 50 360 Table 2-3. Concentrations of trace elements measured within peats and mineral soils. Environmental soil quality guideline data provided from B.C. Ministry of Water, Land and Air Protection (2002) lists element concentrations at which soils must be relocated to non-agricultural lands, and at which a permit is required for disposal. Environment Canada Soil Quality Guidelines (2002) list generalized trace element concentration guidelines for agricultural, residential/parkland and industrial land uses. Cd 120 E a ' ^80 1.40 5 10 15 Radial Distance from Smelter (km) 20 250 _200 1150 Cu \u00E2\u0080\u00A25-100 5 \" 50 0 \"0 5 TO 15 Radial Distance from Smelter (km) 20 5000 Pb \u00E2\u0080\u00A2 \u00C2\u00A3 4000 Q. I 3 3000 \u00E2\u0080\u00A2 S 2000 1 1000 0 1 \u00E2\u0080\u00A2 \u00E2\u0080\u00A2 1) 5 10 \" 1 5 20 Radial Distance from Smelter (km) Ni 20 ? 1 6 \u00C2\u00A3 12 0) \u00E2\u0080\u00A2 \u00E2\u0080\u00A2 i . \u00E2\u0080\u00A2 \u00E2\u0080\u00A2 \u00E2\u0080\u00A2 i 0 5 10 15 ; 20 Radial Distance from Smelter (km) 6000, Zn 4000 S 2000 % 5 10 15 Radial Distance from Smelter (km) 20 Figure 2-2. Concentration of trace elements as a function of the radial distance from the smelter. Interior Concentration (ppm) NJ -U CT> O O O O O O O O O Pb Zn N> O O O 10 15-U 20 25 30 BSed o o o> o o -tr T n, -ui n - - / \\ - m } > ->\u00E2\u0080\u00A2 N> o o o o o o o CO -tk o o o o o o 10 15 20-25 30-BSed \ 7 Sample Depth Sb As Cd Cu Pb Ni Zn (cm) ppm ppm ppm ppm ppm ppm ppm COMINCO MARGIN 0-1 2.9 1.7 1.6 1.8 2.9 0.8 1.4 1-2 3.3 2.1 1.7 2.1 3.2 0.9 1.4 2-3 3.0 3.3 1.4 2.0 3.1 1.2 1.0 3-4 9.9 6.2 9.7 7.3 11.2 1.0 5.7 4-5 8.5 8.8 7.6 6.9 11.5 1.2 4.3 17-20 5.9 13.2 9.6 7.2 15.3 1.0 3.6 COMINCO INTERIOR 2-3 2.6 3.3 0.8 1.5 2.2 0.8 0.8 3-4 9.1 7.9 5.9 5.9 7.9 1.0 4.7 7-8 7.8 8.5 5.3 5.3 8.0 1.0 3.9 8-11 5.6 7.3 0.8 2.6 4.7 1.0 0.7 14-17 31.4 20.4 4.9 16.2 10.0 0.8 2.1 20-23 10.2 14.2 1.3 3.9 6.1 1.0 1.3 32-36 0.8 0.4 0.3 0.8 0.8 0.6 0.2 Basal Sediment 2.2 4.1 0.7 3.0 2.7 0.7 0.5 THUNDER ROAD MARGIN 0-1 6.5 6.7 94.0 3.2 10.1 0.6 14.8 1-2 7.2 7.2 82.9 4.1 12.6 0.7 12.3 2-3 6.3 7.0 110.3 3.3 10.6 0.6 15.8 3-4 11.2 10.7 145.1 3.8 19.6 0.8 18.8 5-6 9.7 11.1 112.5 3.6 19.7 0.8 16.9 11-14 10.4 9.7 130.4 3.8 19.2 0.8 16.7 THUNDER ROAD INTERIOR 0-1 3.7 5.6 21.8 1.7 3.5 0.5 12.0 2-3 4.3 5.9 19.6 2.9 3.2 0.9 10.6 3-4 7.5 8.3 22.0 3.6 4.5 0.9 10.6 5-6 8.4 7.0 26.7 6.0 6.1 1.1 11.4 14-15 5.4 4.6 10.0 5.6 4.2 1.2 5.9 19-20 3.2 1.8 3.6 14.0 1.9 1.1 2.6 Basal Sediment 2.4 1.9 1.1 0.6 1.4 1.0 1.2 CHAMPION LAKES MARGIN 0-1 0.6 0.2 2.3 0.4 1.4 0.2 0.7 1-2 0.7 0.4 3.5 0.5 1.8 0.4 0.9 2-3 2.4 1.0 5.7 0.4 3.1 0.5 1.0 3-4 2.0 0.7 5.4 0.4 3.1 0.3 1.5 4-5 4.6 1.5 8.3 0.6 6.6 0.5 1.9 11-16 7.8 1.5 7.9 0.8 8.8 0.2 1.2 CHAMPION LAKES INTERIOR 2-5 2.2 0.8 3.1 0.3 1.4 0.3 1.0 14-15 5.4 0.9 4.3 0.9 3.0 0.5 1.0 22-26 1.5 0.4 3.9 0.9 0.1 0.5 0.3 35-36 0.7 0.2 1.2 1.0 \u00E2\u0080\u0094 0.7 0.2 49-50 0.4 0.2 1.5 1.0 \u00E2\u0080\u0094 0.7 0.3 63-64 0.5 0.5 0.8 0.7 \u00E2\u0080\u0094 0.6 0.4 79-80 0.3 0.2 0.7 0.6 - 0.6 0.3 BOMBI SUMMIT 0-1 0.8 0.4 1.5 0.6 1.2 0.4 1.2 1-2 1.1 1.1 1.5 0.7 1.5 0.3 1.1 2-3 1.1 3.2 1.5 0.6 1.6 0.4 1.0 3-4 1.6 1.0 3.7 0.9 3.2 0.4 1.1 4-5 2.8 1.2 9.0 1.4 7.9 0.4 1.9 6-7.5 1.1 0.3 0.4 0.3 1.0 0.3 0.5 7.5-9 0.4 0.7 0.9 0.2 0.6 0.5 0.6 Table 2-4. Calculated Peat Enrichment Factors (PEFs) for peats relative to nearby mineral soils. 2.4.1.2 Thunder Road Site Trace elemental concentrations are relatively consistent with depth throughout the profile for the peat sampled near the margin of the Thunder Road site (Table 2-3; Fig. 2-4). In the case of the peat from the centre of the peatland, concentrations decline steadily with depth, with the exception of Cu, which is most concentrated (353 ppm) in the peat immediately above the basal mineral sediment. Copper exists as a free ion in solution under acidic oxidising conditions, but may form a sulphide under low Eh conditions (Brookins, 1988) and so it is hypothesised that dissolved Cu migrates from the peat surface to the zone of reducing conditions at depth, provided that it is not complexed by other mechanisms. Arsenic tends to exist as a soluble species under acidic oxidising conditions, and as a sulphide under reducing conditions (Brookins, 1988), and is present in higher concentrations in the interior peat profile than in the margin profile (Fig. 2-4), similar to the Cominco site (Fig. 2-3). Cd concentrations in the peat from the margin are approximately 4 times higher than the concentrations at the centre of the peatland (e.g. 119 ppm (margin) versus 27.5 ppm (centre) for the 0-1 cm sample). Arsenic, Pb, Zn and Cd decrease with depth in the interior profile, while Sb and Ni concentrations are approximately the same. Unlike the Cominco profile, concentrations are typically lower in the underlying mineral sediment than in the peat, with the exception of Sb, Ni and As, which are approximately the same. Calculated PEFs for Zn and Cd are higher at the Thunder Road site than the Cominco site, despite the lower concentrations of Zn in both profiles and Cd from the interior profile. PEFs for Cd range from 82-130 for the margin peat profile and fall to 4-27 for the interior peats. This suggests that Cd is migrating as an aqueous species from the soil, and is progressively removed from solution by the peat. PEFs indicate that the peat is also enriched relative to the soil in As, Sb, Cu and Pb. Nickel shows no enrichment in the peat. era' 3 1-1 CD K> Margin K> -J o o 3 o a> 3 K. o 3 o w SL ciT o a> a. p o o> BS CD 3 3* CO H 3\" 3 3 Cu CD >-t o a. >-i o Eh * a> w Interior Concentration (ppm) _>.-\u00C2\u00BB. M ro cn o cn o cn _ o o o o o o o o o o o 2.4.1.3 Champion Lakes Site Concentrations of trace elements generally increase with depth in the margin profile, particularly Pb, As and Zn (Table 2-3; Fig. 2-5). In the deeper interior profile, concentrations of As, Pb, Zn, Sb and Cd decrease below 22 cm depth from maximum values near the surface (79.5 ppm Pb, 211 ppm Zn) to minimum concentrations at 80 cm depth. Zinc concentrations are lower in the middle section of the profile (35-50 cm) than at the profile base, suggesting either downward mobilisation from the surface to the base of the profile or upward mobilisation of geogenic Zn from the base of the profile. Copper occurs in higher concentrations below 15 cm, with the highest concentrations occurring between 22 and 50 cm (31 ppm), similar to the pattern of distribution within the interior Thunder Road profile. Nickel concentrations increase below 26 cm to a maximum of 12.6 ppm at 50 cm depth. PEFs for the margin peat indicate that Pb and Cd are enriched in the peat relative to the mineral soil throughout the profile. Antimony, As and Zn are relatively enriched at the base of the peat profile, but not at the surface. PEFs of 1 or less are typical for most elements in the interior peat at depths below 35 cm, with the exception of Cd, which is slightly enriched in the peat (up to 1.5). PEFs are greater than 1 for Sb, As and Pb in the surficial interior peat. However, the actual magnitude of the enrichment is small, due to the relatively-low elemental concentrations in both the peat and the soil, and the degree of preferential sequestration by the peats is minimal for most elements. Arsenic and Pb concentrations occasionally exceed Environment Canada (2002) guidelines for agricultural and residential/parkland use (Table 2-3). 300 200 100 L_ 0+ o o (1) c 40-i 30 20 10 -r- 0 E o a. a. c o (0 k. \u00E2\u0080\u00A2*\u00E2\u0080\u00A2> c a> o . c o o 400 30a 200 100 0 o 30 20 10 0 sample depth -Q c CL N H \u00E2\u0080\u00A2o 0) CO CQ X1 tf> ~0 =3 ._ CO < O O Z t l t H o T\u00E2\u0080\u0094 a) sample depth co Figure 2-5 Concentration of trace elements in the Champion Lakes profiles. 2.4.1.4 Bombi Summit Site Antimony, Cd, Cu, Pb and Zn in the Bombi Summit profile increase in concentration from the surface to a maximum in the 4-5 cm sample, and then decrease to a minimum at the profile base (Figure 2-6). Arsenic is most concentrated in the 2-3 cm sample and Ni concentrations are consistent throughout the profile. Lead, Zn, Cd and As are present at concentrations that exceed the British Columbia (2002) and Environment Canada (2002) soil quality guidelines for agricultural and residential/parkland use. Peat enrichment factors for the site are close to unity for Zn, Cu, As and Sb for all but the 4-5 cm depth sample, while Pb and Cd are relatively concentrated in the peat (up to 8 times for Pb and 9 times for Cd). Nickel is relatively concentrated in the soil by a factor of approximately 2. 2.4.2 Moss Monitoring Results The moss monitoring results are discussed in detail in Goodarzi et al., 2001; 2003, but are summarised briefly here. Arsenic, Cd, Cu, Pb, and Zn deposition was high near the smelter, and decreased with distance (Table 2-5). After correcting for geogenic input, approximately 75 944 kg/ha of Pb and 320 719 kg/ha of Zn were deposited near the Cominco site in the span of a two-year period (1997-1999), based on the results in Goodarzi et al. (2003). During the same period, 14 433 kg/ha of Pb and 64 919 kg/ha of . Zn were deposited in the area around the Thunder Road site, while 52.5 kg/ha of Pb and 0 kg/ha of Zn were measured at the Champion Lakes site. No moss monitoring station is located near the Bombi Summit site. The nearest moss monitoring station is located in the river valley near the town of Castlegar and recorded 125 .3 kg/ha of Pb and 246.9 kg/ha of Zn during the two-year period. 500 400 E Q. Q. C o U\u00E2\u0080\u0094< ca c 0) o c o O sample depth o> CO jd C 0. N + \ .O 3 cm to coincide with the soil data. The average concentrations of As, Cd, Cu, Pb and Zn in the Thunder Road peat are approximately 47-55% those in the Cominco peats, or 80% when the high concentrations of Cd obtained from the margin peat at Thunder Road are included. For the Thunder Road soil, the average elemental concentration is 13% of the Cominco soil concentration for the top 3 cm. Rates of deposition recorded by the Thunder Road moss monitoring station average 25% the Cominco station rate when Cd is included, but drop to 19% when it is excluded (the relative deposition rate for Cd is 48%). This illustrates that Cd is deposited at the Thunder Road site at a rate that is anomalous relative to As, Cu, Pb and Zn, which accounts to some extent for the high concentration found within the peat relative to the soil. Assuming that the Cd is deposited as an oxide, it would be readily dissolved in a moderately acidic environment and will become preferentially enriched in the peat, as Cd has a strong organic affinity (e.g. Sager, 1992) and forms sulphide complexes readily under reducing conditions (Brookins, 1988). Both Cd and Zn behave in a similar fashion and are likely to exist as free ions under the conditions present within an acidic soil (Brookins, 1988). Both Cd and Zn show a strong degree of fractionation in the Thunder Road soil relative to the peat. Although relative deposition rates are 48% and 20% for Cd and Zn, respectively, relative soil concentrations are 3.3% and 4.4%, while relative peat concentrations are 79-213%) and 50-64%, respectively, indicating a strong preferential sequestration within the peat. The relatively high deposition ratio for Thunder Road compared to the lower soil concentration ratio, combined with the peat concentration ratio that is higher than both these parameters, further indicates that trace elements are preferentially sequestered in the peat relative to the mineral soil. The anomalous Cd deposition measured by the moss monitoring station also suggests that there is a secondary source of Cd at this location. The most probable source of Cd is the Teck-Cominco fertiliser factory, which is located near the Thunder Road site and which currently manufactures nitrogen fertiliser, but which previously produced phosphate fertilisers as well. Cd is associated with apatite, the main component of phosphate fertilisers. It is likely that the relatively high Cd deposition rate measured by the moss monitoring station is derived from historical fugitive dust from the fertiliser factory that is circulating in the area. A stream sediment survey (Goodarzi et al., in prep) also detected high concentrations of Cd in this area. Peat Concentration, Relative to Cominco Peat (%) As Cd Cu Pb Zn Average Average (-Cd) Thunder Road 0-3 (M ) 56.6 200.3 42.4 49.2 50.2 79.8 49.6 Thunder Road 0-3 (1) 33.7 83.0 36.6 21.4 60.4 47.0 Thunder Road >3 (M ) 36.4 213.1 42.6 45.4 63.7 80.2 47.0 Thunder Road >3 (1) 18.1 74.9 102.4 19.7 57.9 54.6 Champion Lake 0-3 (M) 4.2 6.7 6.6 3.1 3.5 4.8 Champion Lake 0-3 (1) 4.6 10.4 6.7 3.0 6.2 6.2 Champion Lake >3 (M) 7.2 10.6 8.5 5.3 5.8 7.5 Champion Lake >3 (1) 2.3 8.8 14.6 0.9 2.9 5.9 Bombi <3 10.1 3.5 6.6 2.6 2.3 5.0 Bombi >3 4.1 9.8 9.4 7.3 3.9 6.9 Soil Concentration, Relative to Cominco Soil (%) As Cd Cu Pb Zn Average Thunder Road 0-3 cm 19.5 3.3 23.6 13.6 4.4 12.9 Thunder Road 3-10 cm 32.6 14.7 80.8 29.4 16.5 34.8 Champion Lakes 0-3 cm 18.6 2.8 29.0 4.6 5.3 12.0 Champion Lakes 3-10 cm 55.1 13.1 101.9 10.8 17.0 40.0 Atmospheric Deposition Rate for 1997-1999, relative to the Cominco site station (%) As Cd Cu Pb Zn Average (- Cd) Thunder Road 17.8 48.2 17.4 19.0 20.2 24.5 18.6 Champion Lakes 0 1.1 3.3 0.07 0 0.9 M and I indicate peats sampled from the margin and interior of the peatland, respectively. Table 2-6. Relative concentrations of trace elements in the Thunder Road and Champion Lakes peats and soils, as compared to Cominco peats and soils. Relative rates of deposition as determined by moss monitoring stations are calculated from data in Goodarzi et al., 2001; 2003. The average concentrations of Sb, As, Cd, Cu, Pb and Zn in the Champion Lakes site are 5-7.5% of the Cominco peat concentrations. Average relative soil concentrations are 12-40%, although this average is skewed by the 102% Cu ratio and 55% As ratio in the 3-10 cm Champion Lakes soil. Soil concentration ratios for Cd, Pb and Zn range between 3 and 17%, while the average relative rate of deposition recorded by the moss monitoring station is approximately 1%. The deposition ratio for Cu was anomalously high relative to the other elements, suggesting a localised source, possibly geogenic dust. Average concentrations for Cu in the Elise Formation bedrock range between 38 and 118 ppm (Beddoe-Stephens and Lambert, 1981). This discrepancy between the soil and peat concentration ratios and the rate of deposition strongly suggest a significant geogenic contribution to the peat trace elemental composition, particularly for As and Cu. The extent to which peat is enriched in trace elements relative to the mineral soil is relative to the amount of overall elemental loading at the site (Fig. 2-7). When the average peat trace element concentrations for the intervals of 0-3 cm and >3 cm depth are plotted against [Me]peat - [Me]soji for the same depth intervals, a linear relationship (R2>0.85 for all elements) with a slope of approximately 1 (slope ranges from 0.79 to 1.33) occurs for all elements. The closer the slope is to unity without exceeding it, the greater the element's affinity for the peat relative to the soil. Arsenic, with a slope of 0.88, has the strongest affinity for peat, while the slope of 1.33 for Ni indicates higher concentrations in the soil. The enrichment of trace elements in the peats from areas of heavy deposition illustrates the capacity of organic matter to adsorb and retain metals relative to mineral soils, particularly if the mineral soils contain little clay (Chapter 4) and little organic carbon (0.2-3.5%; Goodarzi, unpublished data). 2.5 Discussion The results of this study demonstrate the potential for natural peatlands to serve as a sink for trace elements released into the environment and the importance of maintaining the existing peatlands in areas which are subject to a large input of trace elements from anthropogenic activities. Experimental constructed wetlands currently in use by Teck-Cominco have been shown to be effective as a means to remove Cd, Zn and As from smelter waste leachate (W. Duncan, personal communication, 2003). In another example, Holmstrom and Ohlander (1999) discuss the disposal of high sulphide mine tailings in anaerobic environments in order to prevent acid mine drainage and trace element mobilization. There, the organic material serves to further immobilize the trace metals. The effective sequestration of trace elements leached from the surrounding soils by natural peatlands supports the development of constructed wetlands for large-scale soil and water remediation projects. Drainage and subsequent oxidation of anthropogenically impacted peat (for urban development, for example) would likely result in the remobilisation of the trace el ements into the surrounding soil and water. Incidences of trace element pollution associated with the oxidation of black shales (Reichenbach, 1993) and with dredging of anaerobic estuarine sludges (Forstner, 1987 and references therein) have been documented. Hence, the release of metals sequestered in peats from highly polluted areas would be cause for concern. The partitioning of Sb, As, Cd, Cu, Pb and Zn between the mineral soils and the peats and the evident vertical translocation of trace elements, particularly Cu, within the profile, demonstrates the mobile nature of the deposited trace elements. This indicates that topsoil sampling programs intended to determine environmental impact of smelters on the surrounding areas may not reflect the full impact of the source, as a significant proportion of the deposited trace elements are subject to migration rather than in situ accumulation. The evidence for post depositional translocation suggests that, prior to sequestration in the peat, the trace elements are highly mobile and bioavailable. For this reason, land use guidelines for areas surrounding Pb-Zn smelters should reflect the potential for trace element impact on the local environment, and make recommendations accordingly to limit the impact of trace elements on the local population. Recommendations might potentially include: restricting agricultural production and home gardening to non-edible plants or plants known not to accumulate metals in the edible parts; prohibiting grazing and feed production for livestock on local soils to prevent potential poisoning or possible bioaccumulation of metals; and limiting the exposure of children to contaminated soils by routinely providing clean surface fill in playgrounds. C U y = 0.7997X \u00E2\u0080\u00A2 O U 0.2155 o co V120 (0 <13 Q. 40 20 40 60 80 100 120 140 160 180 [Me]peat (ppm) _ 250 O ,co 200 CD 5 150 \u00E2\u0080\u009E 10 CO A 5 0 01 0 \" -50 250 o CO 200 cu S 150 i 100 m Cl> i>0 CL cu 0 -50 y = 0.8835X -7.0171 50 100 150 [Mejpeat (ppm) 120 Cd y = 0.5325X +2.163 CO CU s 1 80 Outliers nS 40 \u00E2\u0080\u00A2 cu n \u00E2\u0080\u00A2 a) 0 \u00E2\u0080\u00A2 \u00E2\u0080\u00A2 2 3 20 40 60 80 100 120 140 [Me]peat (ppm) Cu y = 0.8013x-20.733 50 100 150 [Mejpeat (ppm) 200 250 O 4000, CO J2 3000 2000 CO CD q. 1000 CD o 4 V) CU 0 ^ 1 -4 M -8 BSed20-Concentration (ppm) 10 15 BSed 20 r. Thunder Road Site Concentration (ppm) Concentration (ppm) Champion Lakes Site Concentration (ppm) Concentration (ppm) Bombi Summit Site -h-Sb As -EhCd - e - c u \u00E2\u0080\u00940\u00E2\u0080\u0094 Ni Concentration (ppm) IV) CO BSed Pb - \u00E2\u0080\u00A2 - Z n Concentration (ppm) M CO CJ1 O O O O O o o o o o o BSed t f* > \u00E2\u0080\u00A2 Figure 3-2. Concentration of trace elements in the peat profiles. BSed = basal sediment. N i\u00E2\u0080\u0094 s? E Z QJ a I a- s \u00C2\u00AB i i , o a N. CM CO x\u00E2\u0080\u0094 CM CM CN o o o o CO oo CM CO CO CO t T\u00E2\u0080\u0094 co T\u00E2\u0080\u0094 T-(A < JQ E W & Q. o o o o CM C\u00C2\u00BB O CM r t - N t -n rf co s 1- T\" T\" CM CO T-^ o CO i- -si-t- in CM oo CO CM CO t-CM 00 00 CD O O O ^ x- \u00C2\u00AB UD a> co \u00E2\u0080\u00A2>- co to \u00C2\u00A9 ^ T3 \u00E2\u0080\u00A2-ro ra E o \u00E2\u0080\u0094' p a: c \u00C2\u00A7 Q E C CO E u j . r o o m m o O 0 c -a II J\u00E2\u0080\u0094 lt> CO CO LO \u00E2\u0080\u00A2! o o o N \u00C2\u00B0 o o o CO t- O P O Q ^ O o o V o LO CO CM o o o d d o o CM o o o o d d d o \u00C2\u00AB4> co CO >1 o o o o o o o o o o d d o d CO \u00E2\u0080\u00A2t CO Q o o o o o o d d d d CT> CM ^\u00E2\u0080\u0094 o o o o o o o o d o o d to \u00C2\u00A9 ^ \u00E2\u0080\u00A2a \u00E2\u0080\u0094 co ro E O \u00E2\u0080\u0094' p n O u O m .2 o a) i l l i i ._ o SZ SI O I- O I- O CO N o r^ o c ^ d d ^ NJ \u00E2\u0080\u00A2<\u00E2\u0080\u0094\u00E2\u0080\u00A2<\u00E2\u0080\u0094'<\u00E2\u0080\u0094 CM = 0 0 0 0 t! en w cm in p c\j d d o Q. y CO t- CM CM 3 0 0 0 0 fcj g o o o T3 \u00E2\u0080\u00A2 O O O O \u00C2\u00B0 b o d \u00E2\u0080\u00A2 o o o ^ \u00C2\u00B0 d d o N - S 5 S \u00C2\u00A3 \u00C2\u00B0 d d d w \u00C2\u00A9 ^ \u00E2\u0080\u00A2a ^ \u00E2\u0080\u0094 CD cd E O \u00E2\u0080\u0094' c: o \u00C2\u00AE -5. CO E \u00C2\u00A7 g E O JZ \u00C2\u00A3Z O OHOm Table 3-4. Element concentrations in mineral soils (3-10 cm depth) corresponding to the peat sampling sites, and calculated element ratios. Table 3-5. Element ratios normalized to mineral soil for Ti and Zr. Sample Depth (cm) Sb/Ti As/Ti Cd/Ti Cu/Ti Pb/Ti Ni/Ti Zn/Ti COMINCO 0-1 1-2 2-3 3-4 4-5 17-20 15.4 14.6 9.2 11.1 7.3 6.4 7.3 7.7 8.4 6.9 7.6 14.2 17.3 15.4 8.9 10.8 6.5 10.4 11.1 10.6 7.1 8.1 5.9 7.8 18.1 16.5 11.4 12.5 9.9 16.4 1.5 1.3 1.2 1.2 1.0 1.0 12.9 10.0 5.5 6.7 3.7 3.9 THUNDER ROAD 0-1 1-2 2-3 3-4 5-6 11-14 82.7 47.5 48.0 45.6 33.8 37.5 80.3 44.7 49.8 43.8 38.7 34.9 1049.5 480.6 738.6 591.2 392.9 470.4 26.5 17.3 16.3 15.5 12.8 13:7 134.7 86.7 84.7 79.9 68.8 69.3 5.4 3.2 3.3 3.2 2.7 2.8 160.0 70.5 99.6 80.0 56.7 59.6 CHAMPION LAKES 0-1 1-2 2-3 3-4 4-5 11-16 11.6 5.9 3.7 6.1 5.8 32.9 7.4 5.8 2.5 4.9 4.3 15.1 92.4 54.2 16.4 28.7 17.6 57.0 21.5 10.9 1.8 4.0 2.4 9.8 38.3 19.2 6.1 9.7 8.2 36.7 3.5 2.7 0.8 1.2 0.7 1.2 21.4 9.2 4.0 9.4 4.7 10.6 BOMBI SUMMIT 0-1 1-2 2-3 3-4 4-5 7.5-9 0.9 1.0 1.0 1.5 3.6 0.4 0.5 1.2 3.4 1.1 1.8 0.6 3.7 2.9 2.9 4.1 13.0 0.9 1.1 1.0 0.8 1.0 2.2 0.3 1.8 1.9 1.9 3.1 10.1 0.5 0.7 0.4 0.5 0.4 0.5 0.4 1.6 1.2 1.0 1.1 2.8 0.6 Sb/Zr As/Zr Cd/Zr Cu/Zr Pb/Zr Ni/Zr Zn/Zr COMINCO 0-1 1-2 2-3 3-4 4-5 17-20 8.8 9.1 9.0 9.9 6.0 4.5 4.2 4.8 8.2 6.2 6.2 9.9 9.9 9.6 8.6 9.7 5.3 7.2 6.3 6.6 6.9 7.3 4.8 5.4 10.3 '10.3 11.0 11.2 8.1 11.5 0.8 0.8 1.2 1.0 0.8 0.7 7.4 6.3 5.4 6.0 3.1 2.7 THUNDER ROAD 0-1 1-2 2-3 3-4 5-6 11-14 23.2 26.3 21.2 25.3 25.2 25.6 22.6 24.8 22.0 24.3 28.8 23.9 294.8 266.4 326.2 328.2 292.8 321.8 7.4 9.6 7.2 8.6 9.5 9.4 37.8 48.1 37.4 44.3 51.3 47.4 1.5 1.8 1.4 1.8 2.0 1.9 45.0 39.1 44.0 44.4 42.2 40.8 CHAMPION LAKES 0-1 1-2 2-3 3-4 4-5 11-16 1.0 0.7 2.0 2.4 3.2 10.4 0.6 0.7 1.4 1.9 2.4 4.7 8.0 6.5 9.0 11.3 10.0 18.0 1.9 1.3 1.0 1.6 1.4 3.1 3.3 2.3 3.4 3.8 4.6 11.6 0.3 0.3 0.4 0.5 0.4 0.4 1.8 1.1 2.2 3.7 2.7 3.4 BOMBI SUMMIT 0-1 1-2 2-3 3-4 4-5 7.5-9 0.6 0.8 1.0 1.4 2.6 0.3 0.4 1.0 3.7 1.0 1.3 0.6 2.6 2.4 3.1 3.7 9.6 0.8 0.8 0.8 0.9 0.9 1.6 0.3 1.3 1.5 2.1 2.8 7.5 0.4 0.5 0.4 0.5 0.4 0.4 0.4 1.1 0.9 1.1 1.0 2.1 0.5 Trail Pluton Elise Fm Granodiorite K-Andesite Element Concentrations Ti02 % 0.57 0.77 Zr ppm 130.0 114.8 Ni ppm 5.0 6.75 Zn ppm 69.0 90.5 Pb ppm 13.0 N/A Cu ppm N/A 37.75 Ti Ratios Ni 0.001 0.001 Zn 0.01 0.01 Pb 0.002 N/A Cu N/A 0.005 Zr Ratios Ni 0.04 0.06 Zn 0.5 0.8 Pb 0.1 N/A Cu N/A 0.3 Table 3-6. Selected published geochemical data and the resulting caluculated conservative element ratios from the bedrock geology of the Trail Pluton (Sevigny, 1990) and the Elise Formation. (Beddoe-Stephens and Lambert, 1981) Sample Depth (cm) 0 - 1 1 - 2 2-3 3-4 4-5 17-20 O O O O Cu/Zr N/A N/A N/A N/A N/A N/A Pb/Zr 296 295 315 320 232 328 Ni/Zr 2.3 2.3 3.3 2.9 2.3 2.0 Zn/Zr 97 82 '70 79 40 36 Cu/Ti N/A N/A N/A N/A N/A N/A Pb/Ti 1598 1460 1005 1105 877 1454 Ni/Ti 13 12 11 10 9 9 Zn/Ti 523 407 224 273 152 158 \u00C2\u00A79 0 - 1 1-2 2-3 3-4 5-6 11-14 N/A N/A N/A N/A N/A N/A 201 256 199 236 273 252 2.9 3.4 2.8 3.4 3.8 3.7 62 54 60 61 58 56 N/A N/A N/A N/A N/A N/A 2712 1745 1705 1608 1385 1394 39 23 24 23 20 21 829 365 516 415 294 309 Q co Q_ LU < 3 X -1 o 0 - 1 1-2 2-3 3-4 4-5 11-16 0.8 0.6 0.4 0.7 0.6 1.4 18 12 18 20 25 61 1.2 1.9 2.5 2.7 2.3 2.2 2.3 1.4 2.7 4.5 3.3 4.1 0.5 0.2 0.04 0.09 0.05 0.2 N/A N/A N/A N/A N/A N/A 45 34 10 15 9 15 88 38 16 39 20 44 CQ O m D cn 0 -1 1-2 2-3 3-4 4-5 7.5-9 N/A N/A N/A N/A N/A N/A 6.6 8.0 11 15 40 2.3 2.8 2.0 3.0 2.3 2.3 2.0 2.0 1.7 2.0 1.9 3.8 0.9 N/A N/A N/A N/A N/A N/A 21 22 22 36 117 5.8 8.7 5.5 5.9 5.5 6.9 5.3 6.3 4.6 4.0 4.5 11.3 2.2 Table 3-7. Element ratios normalised to bedrock geochemical data listed in Table 3-6. Figure 3-3. Normalised element ratios using soil and rock for the Cominco profile. Bulk concentration data is plotted on the primary (top) axis, while element ratios are plotted on the secondary (bottom) axis. Sb As Cd Cu Pb Ni Zn Os E o CL 0) Q 0) Q. E CO co 17-20 K> 00 O O O o o o o o cn o Ol Concentrat ion (ppm) N> N3 00 O NJ O O O ro ^ O) o o o o o o o o o J\u00E2\u0080\u0094l . O ui - i - i N) o - ^ r o c o o cn o o o o o o o o cn o cn O M O) o o o o o o Ratio [Me]/[Zr] rock ...A... [Me]/[Zr] soil ~s-~[Me]/[Ti] rock [Me]/[Ti] soil Figure 3-4. Normalised element ratios using soil and rock for the Thunder Road profile. Bulk concentration data is plotted on the primary (top) axis, while element ratios are plotted on the secondary (bottom) axis. Sb As Cd Cu Concentrat ion (ppm) o o o \u00C2\u00B0 Ratio [Me]/[Zr] rock [Me]/[Zr] soil [Me]/[Ti] rock [Me]/[Ti] soil Pb Ni Zn Figure 3-5. Normalised element ratios using soil and rock for the Champion Lakes profile. Bulk concentration data is plotted on the primary (top) axis, while element ratios are plotted on the secondary (bottom) axis. Sb As C\ oo Cd D -t^ oo \u00E2\u0080\u00A2 \u00E2\u0080\u00A2 *f< \u00E2\u0080\u00A2 \u00E2\u0080\u00A2 i Cu tration i - [Me ] Pb Ni Zn -A M W CO o o o o \u00C2\u00B0 o o o w u o o o O M ^ O I W O O O O O O W O) o o o Ratio [Me]/[Zr] rock ....... [Me]/[Zr] soil [Me]/[Ti] rock - [Me]/[Ti] soil Figure 3-6. Normalised element ratios using soil and rock for the Bombi Summit profile. Bulk concentration data is plotted on the primary (top) axis, while element ratios are plotted on the secondary (bottom) axis. Sb As Cd Cu Pb Concentration (ppm) \u00E2\u0080\u0094\u00C2\u00BB-[Me] Ni Zn o O -Pi- CO - i N3 CO O O O O O O O Ratio [Me]/[Zr] rock [Me]/[Ti] rock a - [Me]/[Zr] soil - [Me]/[Ti] soil a. 10000 ?1000 Q. Q. I 100 E a) W 10 o Zr R2 = 0.67 \u00E2\u0080\u00A2 Ti R2 = 0.77 1 0 50 100 Ash (%) b. 24 20 16 rsj 12 i -8 4 0 COMINCO THUNDER CHAMPION BOMBI Figure 3-7 a. Plot of the concentrations of Ti and Zr versus the peat ash contents, b. Whisker-Box diagram showing the spread of Ti/Zr ratios for each profile, where the median value is represented by the dot in the middle of the box, the upper and lower extent of the box represent the 75th and 25th percentile, respectively, and the lines extending from the box represent the range of data. 3.4.2.4 Bombi Summit Profile Only in the 4-5 cm sample is the Bombi Summit profile significantly enriched in trace elements relative to the mineral soil. The peat at this depth has high concentrations of all the examined trace elements relative to the rest of the profile with the exception of As, which is enriched in the 2-3 cm sample. The Bombi Summit site is located approximately 16.5 km radial distance from the smelter and is believed to be minimally impacted by the smelter, although it may be subject to anthropogenic impact from secondary sources such as the nearby roadway. At this location, the soil-normalised data closely follows the bulk trace elemental data for all elements except Cu, which has a smoothed profile. This suggests that Cu may have a geogenic source at this site. Lead, Zn and Ni are highly enriched relative to the bedrock (up to 117 times for Pb) when Ti is used for normalization, but show enrichments ranging from less than 1 to a maximum of 40 times (for Pb in the 4-5 cm sample) when Zr is used. This suggests that the published Zr value is closer to reflecting the true background geochemistry at this location than the Ti value. 3.4.3 Discussion These high enrichment factors calculated in the Cominco and Thunder Road peats are due in part to the impact of the smelter at these location, but are also due to the lower Ti concentrations in the peats relative to the bedrock (Tables 3-3 and 3-6) and the tendency for trace elements to be relatively enriched within weathered materials and dust (e.g. Riemann and DeCaritat, 2000). The higher relative Zr concentration in the peats help to negate this effect. These discrepancies in the enrichment factors, depending on the conservative element used for normalisation, illustrate one of the potential shortcomings of this method. The trace elemental and conservative elemental composition of the geogenic component of the samples are almost certainly variable, as the mineralogy differs between samples (Table 3-2). Concentrations of the conservative elements fluctuate independently of the ash content, which can be attributed to both the variable nature of the mineralogy within the peat profiles and to the potential for phytogenic mineral material to contribute significantly to the ash content of the peat. Figure 3-7 illustrates this point\u00E2\u0080\u0094the Ti/Zr ratio is variable, (standard deviation of 5.2, average 10.4, coefficient of variation = 0.503, n=36), rendering questionable the assumption that the conservative elements are a valid proxy for geogenic input. In studies in which trace elemental input is low, this would not be as readily apparent, but when dealing with high concentrations, the discrepancies become more pronounced. Given that the enrichment patterns are controlled by fluctuations of the concentrations in conservative elements relative to the ash content as well as the concentrations in trace elements, enrichment factors are of limited use for determining the extent of anthropogenic versus geogenic impact in the examined sites. This is particularly true for the heavily impacted sites, where the signature of geogenic trace elements is largely masked by the anthropogenic trace elements. Since mineralogy is variable between samples, the ratio of geogenically-sourced trace elements to conservative elements may be variable as well. The fact that the ratio of Ti to Zr is itself variable results in discrepancies in EF, making interpretation difficult. The environmental significance of enrichment factors, called into question by Riemann and DeCaritat (2000) is further illustrated here: the so-called trace element enrichment may be observed as a result of low concentrations of conservative elements. Since there are so many factors controlling the concentration and relative enrichment of trace elements within each of the peat profiles, it is difficult to ascribe an anthropogenic or geogenic source to the trace metals by this method. 3.5 Rare Earth Element Enrichment Patterns 3.5.1 Introduction Rare earth elements have been used to provide a geochemical fingerprint for sedimentary rocks in order to determine provenance. The REE signature is characteristic of the parent rock and although it may be modified by weathering, REE behaviour is considered to be relatively cohesive (e.g. Leybourne et al., 2000). The Lanthanide series of elements behaves in a fairly uniform manner owing to the fact that each element has a +3 charge, although the decreasing ionic radius (from left to right on the periodic table) causes some disparity in behaviour, resulting in fractionation between the light (LREE) and heavy (HREE) rare earth elements. The behaviour of Eu and Ce departs from that of the rest of the series. Ce+3 may be rapidly oxidised to Ce+4, which has a higher surface activity than Ce+3 and the other REEs, and is thus preferentially removed from solution, resulting in a negative Ce anomaly under oxidising conditions. Eu+3 may be reduced to Eu+2, resulting in the formation of a negative Eu anomaly. The relative global abundance of individual elements within the lanthanide series are highly variable between odd and even atomic numbers, and when a plot of REE concentration versus atomic number is graphed, a sawtooth pattern results. When discussing fractionation trends in the lanthanide series, REE concentrations are typically normalised to a chondrite or shale standard, resulting in a smoothed line. A high or low concentration of a single element relative to the rest of the series results in a positive or negative anomaly when normalised to a standard. 3.5.1.1 REE behaviour in the environment The normalised REE pattern for plant tissues typically has a negative Ce anomaly (Akagi et al., 2002), but this anomaly was absent from peats sampled in Japan (Akagi et al., 2002), and from other peat REE data observed in the literature (Krachler et al., 2002). The absence of a Ce anomaly in peats is attributed to the low Eh-pH conditions found within peat-forming environments (Akagi et al., 2002). A negative Eu anomaly was noted in Carex and Sphagnum peats from the surface and from 40 cm depth (Akagi et al., 2002). Peats sampled from the Holland Marsh in southern Ontario and from the Schopfenwaldmoor, near Interlaken, Switzerland, were both found to have slight negative Eu anomalies when normalised to chondrites (Krachler et al., 2002). Chiarnezelli et al. (2001) found that REE compositions associated with lichens and mosses had little relationship to the underlying mineral substrate, and that the REE composition of these plants was derived from atmospheric sources. They (Chiarnezelli et al., 2001) found that the REE composition of vascular plants was variable between species, and that the REE concentrations were partially dependent on the individual species' capacity to take up and accumulate REEs. A review of the literature reveals disparities in the observed behaviour of REE during weathering. In the presence of humic substances, Takahashi et al. (1999) determined a strong tendency for REEs to form organic complexes. The potential for REE to sorb to organic matter was determined experimentally by Eskenazy (1999), who observed that REEs sorb to organic matter at pH > 3, with no tendency for fractionation between HREEs and LREEs. Land et al. (1999), on the other hand, noted fractionation between LREEs and HREEs with depth in a soil profile. Astrom (2001) observed that concentrations of La were depleted at the top of a sulphate-rich soil profile, highly enriched in the transitional zone between oxic and anoxic conditions, and of median concentrations in the anoxic zone. Astrom attributed the observed pattern to the mobilisation of La at the soil surface, and the subsequent preferential scavenging by Fe/Mn oxy-hydroxides at depth (compared to HREE). Middle Rare Earth Element (MREE) enrichments in river waters have been attributed to weathering of phosphate minerals (Hannigan and Shokovitz, 2001), while MREE enrichments in lake waters were attributed to weathering of Fe-Mn oxides/oxyhydroxides (Johannesson and Zhou, 1999). In a discussion of REE weathering behaviour, Johanneson and Zhou (1999) state that HREEs become depleted in weathered sediments, due to complexing reactions with the dissolved organic and inorganic ligands in the weathering solution. Iron-oxide precipitates and carbonate ligands are known to sequester LREEs preferentially to HREEs (Dupre et al., 1996; Leybourne et al., 2000), resulting in negative LREE anomalies in waters and positive LREE anomalies in the Fe and carbonate precipitates. Bau (1999) found that La and possibly Lu had a lower affinity for Fe-oxides than other REEs, while Ce+4 has a higher Fe-oxide affinity. 3.5.1.2 REEs as Geochemical Tracers The REE composition of lake sediments and lake water may strongly reflect the underlying geology (Hall et al., 1995). The REE composition of groundwater may reflect the REE composition of the host bedrock, if the groundwater is not subject to oxidation (which results in negative Ce anomalies) or complexing reactions which remove dissolved REEs from solution (Leybourne et al., 2000). Deep groundwater most closely reflects the host bedrock geology under low pH conditions, as Fe-oxide precipitation reactions occurring under progressively increasing pH conditions subsequently remove REEs from solution (Leybourne et al., 2000). High concentrations of REEs were found in stream waters in an area of Cu-Pb-Zn mining (Protano and Riccobono, 2002). The normalised REE patterns in the stream waters were found to reflect the REE chemistry of leachate from the mine tailings. However, the REE concentrations decreased rapidly downstream due to dilution and precipitation, and the characteristic signature from the leachates was progressively lost (Protano and Riccobono, 2002). The results of previous studies indicate that, while REEs are potentially useful geochemical tracers, they are subject to fractionation in the environment, which may result in the characteristic signature being rendered unrecognisable. The concentrations and chondrite normalised patterns of REEs from smelter wastes and feedstocks are compared to those of peats, soils, atmospheric monitoring media and stream sediments from the surrounding area, in order to determine the effectiveness of using REEs as tracers to measure the impact of the smelter. 3.5.2 Results 3.5.2.1 REE concentrations of smelter materials Rare earth element concentrations were determined for a selection of samples of smelter feedstock and wastes (Table 3-8). The La concentration in the Zn concentrate (feedstock) is 11.8 ppm. Lanthanum concentrations in the slags range from 67.6-73.1 ppm, while the La concentration in the calcine residue from the Indium plant is 17.6 ppm. The high concentrations of REEs found within the smelter wastes relative to the feedstock indicate that REEs are concentrated during processing. La/Lu ranged from 0.48-2.6, and is lowest for the Zn concentrate sample. There is a positive Eu anomaly in both the feedstock and the slags and wastes (Fig. 3-8). 3.5.2.2 Moss Monitoring Station Data Moss monitoring stations closest to the smelter typically have the highest concentrations of REEs (Fig. 3-9; Table 3-9). The patterns from all stations indicate that the REEs collected by the moss are LREE enriched (La/Lu of up to 11.6, from the concentrate unloading site). However, the Cominco station has a relatively low La/Lu of 4.5. No Ce or Eu anomalies were noted in the moss sampling media data. A positive Nd anomaly is present from the monitoring sites closest to the smelter and the ore concentrate site, although no Nd anomoly was detected within the smelter materials. 3.5.2.3 Peats REE concentrations were highest in the Cominco peats, with La concentrations ranging from 15.2-27.3 ppm (Table 3-10). Concentrations of La decreased between sampling profiles in the order Cominco> Bombi Summit> Thunder Road> Champion Lakes. For all profiles, the concentrations of REEs generally showed an increase with increasing peat depth, consistent with the findings of Ohlander et al. (1996) for till . La Ce Pr Nd Sm Eu Dy Ho Er Yb Lu La/Lu Zn Concentrate Off grade slag High Pb slag Indium Plant calcine residue 11.8 13.4 4.9 8.7 4.4 2.2 4.5 3.1 3.4 4.3 2.5 0.5 67.6 114.4 16.9 51.4 12.5 8.2 14.0 4.7 7.6 7.5 3.0 2.4 73.1 128.9 18.0 54.6 13.6 8.8 14.2 4.8 8.2 8.2 3.1 2.4 17.6 29.9 4.2 12.4 2.9 2.0 3.5 1.1 2.1 2.2 0.7 2.6 Table 3-8. Concentration of REE's and normalized La/Lu ratios from selected smelter feedstock and waste samples. 1000 100 10 1 Figure 3-8. Chondrite nomalised REE pattern for selected smelter feedstock and waste samples. La Ce Pr Nd Sm Eu Dy Ho Er Yb Lu \u00E2\u0080\u0094x\u00E2\u0080\u0094 Zn Concentrate \u00E2\u0080\u0094fa\u00E2\u0080\u0094 Off grade slag \u00E2\u0080\u0094a\u00E2\u0080\u0094 Hi.qh Pb slag \u00E2\u0080\u0094\u00C2\u00AE\u00E2\u0080\u0094 Indium Plant calcine residue La Ce Nd Sm Eu Tb Yb Lu Norm. ppm ppm ppm ppm ppm ppm ppm ppm La/Lu Mineral Soil Ore Concentrate site 0-3 cm 44 80 29 4.9 1.1 0.39 1.7 0.25 18.2 Ore Concentrate site 3-10 cm 41 73 25 4.8 1.1 0.61 1.6 0.25 16.8 Cominco 0-3 cm 34 67 24 4.4 1.0 0.53 1.7 0.26 13.8 Cominco 3-10 cm 37 67 23 4.1 1.0 0.34 1.6 0.23 16.9 Thunder Road 0-3 cm 41 83 28 4.9 1.1 0.56 1.8 0.29 14.4 Thunder Road 3-10 cm 38 76 26 5.1 1.1 0.51 1.8 0.27 14.8 Champion Lakes 0-3 cm 49 88 33 6.3 1.3 0.58 2.1 0.31 16.5 Champion Lakes 3-10 cm 30 56 21 4.2 1.2 0.37 1.8 0.26 12.0 Bombi Summit 0-3 cm 27 51 19 3.8 1.1 0.47 1.7 0.27 10.3 Bombi Summit 3-10 cm 41 74 28 5.5 1.2 0.55 1.7 0.26 16.2 Moss Monitoring Stations Ore Concentrate site 0.83 1.45 2.60 0.10 0.02 0.04 0.10 0.01 11.6 Cominco 1.22 1.60 0.65 0.18 0.07 0.16 0.64 0.03 4.5 Thunder Road 0.66 1.20 0.59 0.10 0.02 0.07 0.09 0.01 12.4 Champion Lakes 0.35 0.72 0.23 0.05 0.01 0.02 0.02 0.004 10.2 Bombi Summit 0.60 0.64 0.32 0.07 0.01 0.02 0.04 0.01 6.7 Table 3-9. Concentration of REE's and normalized La/Lu ratios for mineral soils and moss monitoring stations near the peat sampling sites, and near the ore concentrate unloading site. -X-Zn Concentrate Site -B-Cominco ^Thunder Road Bombi Summit -^Champion Lakes Figure 3-9. Chondrite normalised REE pattern for median values of REE's deposited on moss monitoring stations near the peat sampling sites and the Zn-concentrate unloading site. profiles. The high concentrations of REEs at the Comino site relative to the Thunder Road site suggests that REEs are emitted by the smelter. However, the high REE concentrations found within the Bombi Summit site suggest a secondary anthropogenic or a geogenic source. The high ash contents in the Cominco and Bombi Summit site relative to the Thunder Road site (Table 3-2) suggest that the REE conentration is partially a function of the ash content, which may be assumed to be predominantly of geogenic origin. The tendency for concentrations to increase with depth suggests either that the REE's are derived from geogenic sources, or that there is some degree of post-depositional mobility within the peats. The peats in all profiles exhibit LREE enrichment when normalised to a chondrite standard (Fig. 3-10; Table 3-10). This trend is most pronounced in the Cominco peat profile, where La/Lu ranges from 12.6-16.5. The La/Lu ratios decrease in the order Thunder Road> Bombi Summit>Champion Lakes. Although this trend is somewhat consistent with the extent of input from the smelter, the lower La/Lu ratio found within the Champion Lakes profile may be attributable to the more mafic nature of the bedrock when compared to the other sites. The La/Lu ratios were higher in the top 3 cm of the Thunder Road profile than in the deeper samples; no obvious trends in La/Lu versus depth were noted in the other profiles. There is no Ce anomaly in the Cominco, Thunder Road or Bobmi Summit peat profiles, consistent with the findings of Akagi et al. (2002) who found negative Ce anomalies in live plants but not in peats. However, there is a pronounced negative Ce anomaly in the top 2 cm of the Champion Lakes peat profile. The negative Ce anomaly found in plants is also typical of oxidised waters (Leybourne et al., 2000; Protano and Riccobono, 2002) and is probably a reflection of the chemistry of the water taken up by the plants. The negative Ce anomaly found at the peat surface suggests that either the peat at the profile surface is composed of relatively unhumified plant material that has retained the REE signature characteristic of living plants, and/or that the interstitial water is oxidised. There is a slight negative Eu anomaly in all profiles, with the exception of Bombi Summit, consistent with findings from other peat studies (Akagi et al., 2002, Krachler et al., 2002). This negative anomaly is most pronounced in the uppermost samples of the peat profiles in the case of the Cominco and Thunder Road sites. 3.5.2.4 Soil The concentrations of REEs in the mineral soils sampled close to the peat sampling locations and near the ore concentrate unloading site do not decrease with radial distance from the smelter as they do with the peats (Table 3-9; Fig. 3-11). The highest La concentration is found in the Champion Lakes 0-3 cm soil, 13.5 km from the smelter. Lanthanum concentrations are only slightly higher at the ore concentrate unloading site than at the Cominco or Thunder Road sites. The concentrations of REEs measured in the mineral soils are higher than the concentrations found within the peats, indicating that REEs are not preferentially sequestered in the peat. In contrast, the trace elements Sb, As, Cd, Cu, Pb and Zn are concentrated in the peats relative to the mineral soils at the sampling sites close to the smelter (Chapter 2). This suggests that smelter-derived REEs deposited on the mineral soil are less subject to post-depositional mobilisation and sequestration in the peat than the trace elements. Additionally, the relative proportion of geogenic versus smelter-emitted REEs in the mineral soil is likely to be higher than for the aforementioned trace elements. It is probable that geogenic elements will be concentrated in the mineral soil relative to the peat, and so any characteristic REE geochemical signature from smelter emitted materials is likely to be more \"diluted\" in the mineral soil. Similar to the peats, the mineral soils are LREE enriched when normalised to chondrites (Fig. 3-11). The Champion Lakes soil has the lowest La/Lu ratio (Table 3-9), consistent with the peat data (Table 3-10). The 0-3 cm soil from the ore concentrate unloading site has the highest La/Lu. No Ce or Eu anomalies were noted for any of the soils, unlike the peat, indicating that geochemical fractionation is taking place within the peats subsequent to REE incorporation. / Sample Depth (cm) La Ce Nd Sm Eu Tb Yb Lu Norm ppm ppm ppm ppm ppm ppm ppm ppm La/Lu Cominco 0-1 15.2 26.4 1.7 1.9 0.4 0.4 0.9 0.1 14.3 1-2 17.4 31.2 3.2 2.2 0.5 0.4 1.1 0.1 12.9 2-3 24.8 47.2 3.5 3.2 0.6 0.3 1.5 0.2 13.6 3-4 20.8 38.4 1.4 2.7 0.5 0.4 1.3 0.1 16.6 4-5 27.3 50.5 2.5 3.4 0.6 0.4 1.4 0.2 15.4 17-20 23.0 41.2 2.4 2.9 0.7 0.5 1.2 0.2 12.6 Thunder Road 0-1 5.1 8.4 1.6 0.6 0.1 0.1 0.3 0.04 14.6 1-2 6.6 11.3 1.3 0.9 0.1 0.1 0.3 0.06 10.9 2-3 4.9 7.7 2.0 0.6 0.1 0.1 0.4 0.03 15.0 3-4 7.0 11.5 1.6 0.9 0.2 0.1 0.5 0.07 10.2 5-6 7.0 12.3 1.3 0.9 0.2 0.2 0.4 0.07 10.2 11-14 8.1 13.3 0.5 1.1 0.2 0.1 0.5 0.08 10.3 Champion Lakes 0-1 0.5 0.3 0.5 0.1 0.03 0.1 0.1 0.01 9.9 1-2 1.0 1.1 5.4 0.2 0.1 0.2 0.1 0.01 10.3 2-3 6.8 12.0 3.4 1.0 0.3 0.1 0.4 0.08 9.2 3-4 3.4 5.9 5.4 0.5 0.1 0.1 0.2 0.05 6.8 4-5 7.8 14.0 2.0 1.1 0.3 0.2 0.5 0.09 8.6 11-16 2.4 4.6 2.2 0.4 0.1 0.1 0.2 0.03 8.8 Bombi Summit 0-1 11.4 21.6 1.1 1.7 0.4 0.3 0.8 0.1 8.9 1-2 14.5 27.0 1.0 2.3 0.7 0.4 0.9 0.2 9.7 2-3 17.1 32.5 1.0 2.6 0.7 0.4 1.1 0.2 11.3 3-4 17.0 31.6 1.3 2.6 0.7 0.4 1.1 0.2 9.7 4-5 12.9 22.8 0.9 1.8 0.4 0.2 0.8 0.1 9.5 7.5-9 22.5 39.5 0.5 3.4 0.8 0.1 1.5 0.3 8.8 Table 3-10. Concentration of REE's and normalized La/Lu ratios. 00 K> I\u00E2\u0080\u0094T . CTQ c >-1 CD n cr o E3 O. >-t t3 O ft o-s tn 51 i -I TS ft a H o 52 ?T 10 La Ce Nd Sm Eu Tb Yb Lu -0-1 \u00E2\u0080\u0094 1-2 \u00E2\u0080\u00942-3 \u00E2\u0080\u00943-4 \u00E2\u0080\u00944-5 \u00E2\u0080\u009417-20 100 CHAMPION LAKES La Ce Nd Sm Eu Tb Yb Lu - 0 - 1 - 1 - 2 - 2 - 3 -a-3-4 - 4 - 5 -11 -16 0-1 - 1 - 2 \u00E2\u0080\u00942-3 - 3 - 4 \u00E2\u0080\u00945-6 \u00E2\u0080\u009411-14 -0 -1 - 1 - 2 - 2 - 3 - 3 - 4 - 4 - 5 -7.5-9 100 10 1 La Ce Nd Sm Eu Tb Yb Lu 1000 100 10 1 La Ce Nd Sm Eu Tb Yb Lu -x-Zn Concentrate Site -e-Cominco -a-Thunder Road Bombi Summit -i-Champion Lakes Figure 3-11. Chondrite normalised REE's for mineral soils near the peat sampling sites and near the ore concentrate unloading site. 3.5.2.3 Peat Data Normalised to Soil Data In order to examine how REEs are fractionated between the peat and mineral soil, the peat REE concentration data was normalised to the 0-3 cm and 3-10 cm mineral soil data (Figs. 3-12 and 3-13). Following normalisation, the LREE element enrichment pattern present in the peat and soil disappears, indicating that LREE enrichment is not controlled by the nature of the environmental sampling media in this case. The negative Eu anomaly persists in the Cominco peat profile and to a lesser extent in the Thunder Road profile, indicating that the Eu anomaly occurs as a result of the reducing conditions present within the peat. The main feature that appears as a result of the normalisation is a positive Nd anomaly, which is pronounced in the Thunder Road profile, and is present to a lesser extent in the Cominco profile and to a slight extent in the upper samples of the Champion Lakes profile. Protano and Riccobono (2002) found that Nd is scavenged from solution by Fe-oxides more readily than other REEs. Iron oxides have been shown to be important in the retention of trace elements in both peat and soils, and the positive Nd anomaly is most pronounced in the surface peats, where oxidising conditions are most prevalent in the profile. However, the high affinity of Fe-oxides for Nd would suggest a lower potential for migration from the soil to the peat than for the other REEs. The reason for the positive Nd anomaly in the peat is therefore uncertain, normalised to soil. The apparent positive Tb anomaly is due to the data handling practice of assigning a value of Vi the detection limit when concentrations are below the detection limit. It seems likely from the data pattern that this assigned value is too high. 3.5.2.5 Stream Sediment Data Stream sediments have similar REE patterns to soil data (Fig. 3-14). No Ce or Eu anomalies are present in any of the stream sediment samples. Apparent anomalies in the Dy-Yb-Lu series may be due to decreased analytical precision as a result of low concentrations, or may reflect a real anomaly. LREE enrichment is also found in the stream sediments, with the highest LREE enrichment occurring in the sediment sampled near to the ore concentrates unloading site (Ryan Creek La/Lu-17.1). LREE enrichment decreases with decreasing influence from the smelter, from Trail Creek, equivalent to the Cominco site (La/Lu of 16.2) to Topping Creek, equivalent to the Thunder Road site (La/Lu of 14.6) to Champion Creek, equivalent to the Champion Lakes site (La/Lu of ^-0-1 \u00E2\u0080\u0094\u00E2\u0080\u00A2\u00E2\u0080\u00941-2 \u00E2\u0080\u0094 2 - 3 ^ 3 - 4 -*-4-5 \u00E2\u0080\u0094\u00E2\u0080\u00A2\u00E2\u0080\u0094 17-20 La Ce Nd Sm Eu Tb Yb Lu - - -1 -2 -^\u00E2\u0080\u00942-3 ^ 3 - 4 \u00E2\u0080\u0094 5-6 \u00E2\u0080\u0094^ 11-14 La Ce Nd Sm Eu Tb Yb Lu - ^ 0 - 1 \u00E2\u0080\u0094\u00E2\u0080\u00A2\u00E2\u0080\u00941-2 2-3 - ^ 3 - 4 \u00E2\u0080\u0094x\u00E2\u0080\u00944-5 \u00E2\u0080\u00A2 11-16 Figure 3-12. REE's for peat normalised to the nearest mineral soil (0-3 cm depth). La -\u00E2\u0080\u00A2-0-1 -*\u00E2\u0080\u0094 3-4 Ce Nd Sm 1-2 \u00E2\u0080\u00A24-5 Eu Tb Yb 2-3 \u00E2\u0080\u00A217-20 Lu 0.01 0.01 0.001 La Ce - \u00E2\u0080\u00A2 - 0-1 -*\u00E2\u0080\u0094 3-4 Nd Sm Eu La Ce \u00E2\u0080\u00A2 - 0 - 1 -*\u00E2\u0080\u00943-4 1 - 2 -*\u00E2\u0080\u0094 5-6 Tb -Ar\u00E2\u0080\u0094 2-3 -\u00E2\u0080\u00A2\u00E2\u0080\u009411-14 Yb Nd Sm - 1 - 2 Eu 4-5 Tb Yb - A \u00E2\u0080\u0094 2 - 3 -\u00E2\u0080\u00A2\u00E2\u0080\u009411-16 Lu Lu Figure 3-13. REE's for peat normalised to the nearest mineral soil (3-10 cm depth). 1 . , La Ce Nd Sm Eu Tb Dy Yb Lu \u00E2\u0080\u00A2s\u00E2\u0080\u0094 TRAIL CREEK CHAMPION CREEK*- RYAN CREEK (COMINCO) (CHAMPION LAKES) (Zn CONCENTRATE SITE) TOPPING CREEK TOPPING CREEK (THUNDER ROAD) (THUNDER ROAD) Figure 3-14. Chondrite normalised REE pattern for stream sediments collected near the peat sampling sites and near the Zn-concentrate unloading site. 9.8). Overall concentrations of REEs also decrease with increasing distance from the smelter, from 113 ppm La at Ryan Creek, to 46 ppm La at Champion Creek. 3.5.3 Discussion The REE concentrations within the smelter feedstock samples are lower than the REE concentration in the Cominco and Bombi Summit peats, and lower than the soil REE concentrations at any site. Concentrations of REEs were elevated in the smelter waste materials (slags) relative to the peats and soils. The pronounced LREE enrichment seen in the peat, soil, stream sediments and most of the moss monitoring sampling media is absent from all the analysed smelter samples (Table 3-8; Fig. 3-8), despite the high La/Lu observed for moss monitoring media and stream sediments sampled near the concentrate unloading site. There is a positive Eu anomaly in both the feedstock and the slags and wastes, that was not noted in any of the environmental sampling media (Fig. 3-8). These results suggest two possibilities: 1. LREE enrichments observed in the sampled moss, peat, soils and stream sediments are due to weathering and preferential loss of HREE in smelter emitted materials. Preferential weathering of HREEs in sediments was observed by Ohlander et al. (1996) and Johannesson and Zhou (1999). 2. The pronounced LREE enrichment in the peats, soils and stream sediments is due to the natural background geochemistry of the sampled materials and the impact of the smelter is relatively insignificant to the REE signature. The less pronounced LREE enrichment in the moss monitoring stations is as a result of the combined input of smelter-derived particulates and geogenic dust. Given that the media in the moss monitoring stations is changed every three months, which is unlikely to be sufficient time to degrade the trapped particulates sufficiently to mobilise the HREEs, it is most likely that the observed LREE enriched signature is due primarily to the natural local geochemistry. The similar La/Lu values for corresponding peat and mineral soil sampling sites support the geogenic origin of the LREE enrichment. The low La/Lu at the Cominco moss 'monitoring station reflects the influence of the smelter to a greater extent than the peat and soil at this location, as peat and soil are more impacted by geogenic factors than the moss. With increasing distance from the smelter, the La/Lu generally increases in the moss monitoring media, indicating a decrease in the smelter impact. 3.6 Conclusions Attempts to apply geochemical signature techniques to differentiate between anthropogenic and geogenic trace metal inputs in an area impacted by a Pb-Zn smelter were generally unsuccessful. Element ratios were found to produce unsatisfactory results due to the highly variable nature of the geogenic \"conservative\" elements within each profile. Given that these elements do not necessarily represent a stable geochemical baseline in the examined samples, they are not suitable parameters for normalisation. The factors controlling the post-depositional mobility of the trace elements (e.g. redox conditions, hydrogeological flow paths) are independent of the factors that controlled the incorporation of geogenic materials throughout the depositional history of the peat (e.g. flooding, wind) and relative enrichment of conservative elements and trace elements may occur independently of each other or of anthropogenic input. Element ratios have been shown to be effective in chronostratigraphic trace element studies of ombrotrophic peats subject to deposition by less mobile species (e.g. Shotyk, 1996; Shotyk et al., 1996). However, the ambiguous results obtained by this study illustrate that the conservative element ratio method is probably unsuitable for sites subject to a high input of mobile anthropogenic trace elements. Furthermore, the environmental significance of enrichment ratios should not be accepted uncritically, as a high degree of enrichment is as likely to be the result of the depletion of the conservative element as the enrichment of the trace element in question. Despite the high rates of trace element deposition from the smelter to the surrounding area, the relatively flat REE signature of smelter materials contrasted with the pronounced LREE enrichment in the sampling media used in this study. LREE enrichments were found in the peats, soils, stream sediments and, to a lesser extent, moss monitoring media, while the REE signature of an assortment of smelter materials was relatively flat, with a positive Eu anomaly that was not seen in any of the environmental sampling media. This suggests that the LREE enrichment is characteristic of the background geochemistry of the sampled media and of the geogenic dust captured by the moss monitoring stations, and that the impact of the smelter on local REE signatures is relatively minor. These findings indicate that while the REE signatures of waters have been shown to be useful geochemical tracers in some cases, REE signatures from emitted smelter materials are subject to masking by the geochemistry of the surrounding environment, and are of limited use as tracers in environmental studies. 3.7 References Akagi, T, Feng-Fu, F. and Tabuki, S., 2002. Absence of Ce anomaly in the REE patterns of peat moss and peat grass in the Ozegahara peatland. Geochemical Journal, 36: 113-118. Astrom, M., 2001. Abundance and fractionation patterns of rare earth elements in streams affected by acid sulphate soils. Chemical Geology, 175: 249-258. Bau, M., 1999. Scavenging of dissolved yttrium and rare earths by precipitating iron oxyhydroxide: Experimental evidence of Ce oxidation, Y-Ho fractionation and lanthanide tetrad effect. Geochimica et Cosmochimica Acta, 63: 67-77. Beddoe-Stephens, B. and Lambert, R.StJ., 1981. Geochemical, mineralogical and isotopic data relating to the origin and tectonic setting of the Rossland volcanic rocks, southern British Columbia. Canadian Journal of Earth Sciences, 18: 858. Chiarenzelli, J., Aspler, L., Dunn, C., Cousens, B.; Ozarko, D. and Powis, K., 2001. Multi-element and rare-earth element compostion of lichens, mosses and vascular plants from the Central Barrenlands, Nunavut, Canada. Applied Geochemistry, 16: 245-270. Coedo, A, G., Dorado, M.T., Padilla, I. and Alguacil, J., 1998. Use of boric acid to improve the microwave-assisted dissolution process to determine fluoride forming elements in steels by flow injection inductively coupled plasma mass spectrometry. Journal of Analytical Atomic Spectrometry, 13: 1193-1197. Dupre, B., Gaillardet, J., Rousseau, D. and Allegre, C.J., 1996. Major and trace elements of river-borne material: The Congo Basin. Geochimica et Cosmochimica Acata 60: 1301-1321. Eskenazy, G.M., 1999. Aspects of the geochemistry of rare earth elements in coal: an experimental approach. International Journal of Coal Geology, 38: 285-295. Goodarzi, F., Sanei, H. and Duncan, W.F., 2001. Monitoring the distribution and deposition of trace elements associated with a zinc-lead smelter in the Trail area, British Columbia, Canada. Journal of Environmental Monitoring, 3: 515-525 Goodarzi, F., Sanei, H., Garrett, R.G. and Duncan, W.F., 2002. Accumulation of trace elements on the surface soil around the Trail smelter, British Columbia, Canada. Environmental Geology, 43: 29-38. Goodarzi, F., Sanei, H. and Duncan, W.F. 2003. Deposition of trace elements in the Trail region, British Columbia; an assessment of the environmental effect of a base metal smelter on land. Geological Survey of Canada Bulletin 573, 50 pp. Hannigan, R.E. and Sholkovitz, E.R., 2001. The developmnt of middle rare earth element enrichments in freshwaters: weathering of phosphate minerals. Chemical Geology, 175: 495-508. Hall, G.E.M., Vaive, J.E. and McConnell, J.W., 1995. Development and application of a sensitive and rapid analytical method to determine the rare-earth elements in surface waters. Chemical Geology, 120: 91-109. Johannesson, K.H. and Zhou, Xi., 1999. Origin of middle rare earth element enrichments in acid waters of a Canadian High Arctic Lake. Geochimica et Cosmochimica Acta, 63: 153-165. Krachler, M., Mohl, C., Emons, H. and Shotyk, W., 2002. Influence of digestion procedures on the determination of rare earth elements in peat and plant samples by USN-ICP-MS. Journal of Analytical. Atomic Spectrometry, 17, 844-851. Land, M., Ohlander, B., Ingri, J. and Thunberg, J., 1999. Solid speciation and fractionation of rare earth elements in a spodosol profile from northern.Sweden as revealed by sequential extraction. Chemical Geology, 160: 121-138. Leybourne, M.I., Goodfellow, W.D., Boyle, D.R. and Hall, G.M., 2000. Rapid development of negative Ce anomalies in surface waters and contrasting REE patterns in groundwaters associated with Zn-Pb massive sulphide deposits. Applied Geochemistry, 15: 695-723. Little, H.W., 1982. Geology of the Rossland-Trail Map-Area, British Columbia. Geological Survey of Canada Paper 79-26, 38p. Prohaska, T., Hann, S., Latkoczy, C. and Stingeder, G., 1999. Determination of rare earth elements U and Th in environmental samples by inductively coupled double focusing sector field mass spectrometry (ICP-SMS). Journal of Analytical Atomic Spectrometry, 14: 1-8. Protano, G. and Riccobono, F., 2002. High contents of rare earth elements (REEs) in steram waters of a Cu-Pb-Zn mining area. Environmental Pollution, 117: 499-514. Reimann, C. and De Caritat, P., 2000. Intrinsic flaws of element enrichment factors (EFs) in environmental geochemistry. Environmental Science and Technology, 34: 84- 91. Sevigny, J.H., 1990. Geochemistry of the Jurassic Nelson plutonic suite, southeastern British Columbia. In: Project Lithoprobe; southern Canadian Cordillera transect workshop. Lithoprobe Report 11, pp. 41-52. Shotyk, W., 1996. Natural and anthropogenic enrichments of As, Cu, Pb, Sb, and Zn in rainwater-dominated versus groundwater-dominated peat bog profiles, Jura Mountains, Switzerland. Water, Air and Soil Pollution, 90: 375-405. Shotyk, W., Cheburkin, A.K., Appleby, P.G., Fankhauser, A. and Kramers, J.D., 1996. Two thousand years of atmospheric arsenic, antimony and lead deposition recorded in an ombrotrophic peat bog profile, Jura Mountains, Switzerland. Earth and Planetary Science Letters, 145: E1-E7. Shotyk, W., Cheburkin, A.K., Appleby, P.G., Fankhauser, A. and Kramers, J.D., 1997. Lead in three peat bog profiles Jura Mountains, Switzerland: Enrichment factors, isotopic composition and chronology of atmospheric deposition. Water, Air and Soil Pollution, 100: 297-310. Takahashi, Y., Minai, Y., Ambe, S., Makide, Y. and Ambe, F., 1999. Comparison of adsorption behavior of multiple inorganic ions on kaolinte and silica in the presence of humic acid using the multitracer technique. Geochimica et Cosmochimica Acta, 63: 815-836. Wedepohl, K.H., 1995. The composition of the continental crust. Geochimica et Cosmochimica Acta, 59: 1217-1232. Wiist, R.A.J., Ward, C.R., Bustin, R.M. and Hawke, M.I., 2002. Characterization and quantification of inorganic constituents of tropical peats and organic-rich deposits from Tasek Bera (Peninsular Malaysia): implications for coals. International Journal of Coal Geology, 49: 215-249. Chapter 4 Particulate matter in peat from the environs of a Pb-Zn smelter determining geogenic and anthropogenic input 4.1 Introduction Most environmental trace element studies utilise a variety of chemical and statistical methods in order to determine the impact of a source of contaminants. A smelter operation emits particulate matter rich in trace metals into the surrounding environment, in the form of particles emitted during the processing, and fugitive dust released during the transporting and storage of ore materials. Particulate matter may also be derived from local soils and sediments as a result of weathering processes, and may contain high concentrations of geogenic trace elements. Peat in the vicinity of a point source of particulate emissions is a sink for both atmospheric particle deposition and elements mobilised from the surrounding environment. Ash materials derived from peats sampled from the area surrounding a Pb-Zn smelter in Trail, British Columbia, Canada were observed using scanning electron microscopy (SEM). The primary objective was to observe the size, elemental composition and morphology of particles containing heavy elements. Natural mineral matter typically exhibits crystalline characteristics and has an angular morphology, while anthropogenic particulate matter emitted from a smelter is typically rounded, as a result of rapid solidification during cooling in the stack (Goodarzi et al., 2001; 2003). The chemistry of the anthropogenic and geogenic particles also differs. Materials emitted from the smelter during processing are typically metallic oxides resulting from the roasting process, and silicate fly ash from coal combustion, while geogenic particles will reflect the local geology. Energy Dispersive Spectroscopy (EDX) is used to determine elemental associations, which help to determine the major modes of occurrence for elements in the particulate matter found within the peats. Examination of the particulate matter using SEM-EDX allows the determination of the elemental makeup of the observed particles, and thus makes it possible to relate chemistry and particle morphology in order to determine source. Differentiating between anthropogenic and geogenic sources of trace elements in an area of heavy anthropogenic impact, such as a smelter, is difficult by bulk chemical methods alone. It is not reasonable to assume that there is no geogenic impact, or that the background geochemistry will be uniform throughout the sampling area, if indeed a reasonable baseline geochemistry can be established. An SEM-EDX study may help in determining the nature of the particulate matter, and the elemental composition of geogenic minerals, and may reveal evidence of industrial impact such as fly ash particles. The purpose of this study is to qualitatively observe the morphology and elemental composition of particulate matter found within peats in the vicinity of a Pb-Zn smelter, in order to determine the source. This paper discusses the results of one phase of a project which examines the role of peat as a sink for trace elements in the area surrounding a Pb-Zn smelter. Other phases of this project have examined the total concentration of selected trace elements (Sb, As, Cd, Cu, Pb, Ni and Zn) in peat profiles in the vicinity of the smelter, and discussed the results with reference to measurements of atmospherically deposited trace elements (Goodarzi et al., 2001; 2003) and trace element concentrations in nearby mineral soils (Chapter 2). A six-step sequential leaching procedure was applied to determine the mode of occurrence of selected trace elements in the peat profiles (Chapter 5). The mode of trace element occurrence is discussed in the context of the early diagenetic conditions within the peat, as determined by organic petrography (Chapter 6). 4.2 Sampling Locations The Teck-Cominco smelter is located in Trail, British Columbia, situated in the Columbia River Valley within the Columbia Mountains (Fig. 4-1). The smelter has been in operation since 1896, and produces Pb and Zn as it's primary products, as well as Cd, In, Ge, Ag, Au, Bi, Cu, As, sulphuric acid and ammonium sulphate fertiliser. The valley is subject to the deposition of materials containing elevated concentrations of Pb and Zn, as well as associated elements such as Sb, As, Cu, and Cd. These elements are known to be derived both from material emitted from the smelter during processing, and from fugitive emissions, such as dust from stored concentrate piles (Goodarzi et al., 2001; 2003). The area is underlain primarily by Jurassic/Cretaceous plutonic rocks, emplaced during the Columbian Orogeny (the Nelson Intrusives), and Jurassic metavolcanic and metasedimentary rocks (the Elise Formation). The geochemistry of the area is complex and variable. A compilation of published bedrock geochemical data (Sevingy, 1991; Beddoe-Stephens and Lambert, 1981) shows the variability in element concentrations between rock types in the area (Table 4-1). Small and large scale mining operations have been active within the area over the past century, as a result of the numerous localised ore deposits. In areas such as this, it is difficult to confidently assign baseline geochemistry in order to assess the environmental impact of the smelter. Three sites were selected in order to obtain a representation of the lateral distribution of trace elements in the areas surrounding the smelter. Site selection criteria included distance and direction from the smelter, bedrock geology, and availability of organic sediments. The latter posed a problem, as peatlands in the Trail area are few in number due to the relatively dry climate. A description of the sampling sites is provided in Table 4-2, and locations are indicated on Figure 4-1. Nelson Intrusives Elise Formation % Granodiorite Quartz Gabbro K-Tonalite Granodiorite Ankaramite Basalt K-Andesite Si02 Ti02 AI2O3 Fe203 MnO MgO CaO Na20 K 2 0 P 2 0 5 64.2 0.6 16.0 4.9 0.1 2.0 4.8 3.5 3.1 0.2 54.2 0.9 17.5 9.7 0.2 4.2 7.0 4.0 1.8 0.3 60.5 0.6 16.9 6.4 0.1 2.4 4.8 4.7 2.9 0.3 66.0 0.4 16.5 3.0 0.1 1.1 4.0 4.1 3.4 0.2 48.1 0.8 12.2 12.9 0.2 12.4 9.4 2.0 1.6 0.3 51.3 0.9 14.5 11.6 0.2 6,4 9.4 3.1 1.8 0.3 55.4 0.8 15.1 9.4 0.1 4.1 7.8 3.8 2.8 0.3 ppm V Cr Ni Zn Ga Rb Sr Y Zr Nb Ba Pb Th Cu 100 20 5 69 18 93 654 18 130 16 1039 13 9 223 32 13 126 21 72 744 20 65 8 809 9 5 130 22 7 82 19 96 700 21 122 12 1057 9 6 59 10 5 54 17 102 782 14 107 13 1418 12 6 264.3 664.2 212.2 97.2 39.2 541.5 14.5 61.8 2.8 588.2 118.2 314.5 125.8 39.8 97.2 38 755.8 18.5 89.5 3.8 685 63.8 222.8 26.5 6.8 90.5 52.2 889.5 17.2 114.8 4.2 939.2 37.8 Table 4-1. Compilation of published geochemical data, for the Nelson Intrusives (Sevigny, 1990) and the Elise Formation (Beddoe-Stephens and Lambert, 1982). |49\u00C2\u00B015' QUATERNARY \u00E2\u0080\u00A2UnconsoSdated sediments; till, sand yavel, silt JURASSIC/CRETACEOUS j \u00E2\u0080\u0094 \u00E2\u0080\u0094 | NELSON INTRUSIONS: A A granodiorite; miner quartz r I diorita and diorite i \u00C2\u00BB -i ROSSLAND MONZONITE: x x ' J biotite-taxnblende-augrte L \u00E2\u0080\u0094 J monzonte, manly medium grained 1 ELISE FORMATION: . flow breccia, massive ande sites J and basalts, agglomerate, tuff, breccia, laminated siltstone MOUNT ROBERTS FORMATION: 5black siltstone and argillaceous quartette, slate, greywacke, chert, pebble conglomerate, lava; limestone AGE UNKNOWN TRAIL GNEISS: amphibotite and grey biotits gneiss, hornblende gneiss, rreca schist, aptite and pegmatite Kilometres 1 0 OT~ Figure 4-1. Geological map of the Trail area (from Little, 1982) showing sampling locations. Site Bedrock Geology Vegetation pH and Comments Cominco UTM Zone 11, 0446226, 5440375 Trail Pluton (granodiorite, quartz diorite) Typha latifolia (common cattail), Epilobium ciliatum (purple leafed willow herb) Carex urticulata (beaked sedge) Equisetum palustre, and Deschampsia cespitosa (tufted hairgrass) 5.3 (surface) 5.6 (mineral sediment) 5.7 (pore water) -saturated at the time of sampling, although gleying was noted in the uppermost 15 cm-intermittently aerobic. Zones of oxidation were noted around roots. Thunder Road UTM Zone 11, 0445145, 5440974 Trail Pluton (granodiorite, quartz diorite) Typha latifolia (common cattail), Pinus sp. (pine) Betula sp. (birch) Epilobium ciliatium Equisetum palustre, and Deschampsia cespitosa (tufted hairgrass) 5.0 (surface) 5.4 (mineral sediment) 5.7 (pore water) -watertable was approximately 10 cm below the surface at the time of sampling Champion Lakes Provincial Park UTM Zone 11, 0453623, 5448726 Elise Formation (flow breccia, lava agglomerate, volcanic breccia, tuff, tuffaceous conglomerate, andesite, basalt, augite porphyry, metamorphosed to greenschist fades). Limestone xenoliths and calcite amygdules found within mafic flows. Economic deposits of Pb, Zn, Ag, associated with sulphides. Carex sp. Nuphar lutea (cow lily) Assorted grasses 6.5 (surface) 6.5 (15cm depth) 6.4 (pore water) Saturated profile Table 4-2. Description of the sampling sites: location, bedrock geology, vegetation and conditions within the peat profile. 4.3 Methodology Peats were sampled by digging pits with a stainless steel shovel and cutting blocks of peat from the pit wall. The peat blocks were immediately sealed in plastic freezer bags and refrigerated within 24 hours. Peat samples were combusted at 400\u00C2\u00B0C for 24 hours, and the mineralogy of the resulting ash residue was determined by X-ray diffraction. Interpretation of the XRD spectra was aided by the use of PC-APD (version 3.6), which also provides data for the normalization of peak heights, permitting semi-quantitative interpretation. Samples of peat ash material were carbon, coated for observation with the SEM in back-scattered electron mode. This procedure was not conducted with the intention of providing quantitative information, and as such no point counting or image analysis was performed, rather it was an attempt to characterise the morphology and chemistry of the materials observed to make up a significant portion of the ash. The elemental composition of selected particles was determined by EDX. Trace element concentrations of the whole peat samples were determined by Instrumental Neutron Activation and ICP-MS (Becquerel Laboratories, Mississaugua, Canada). 4.4 Results and Discussion 4.4.1 Trace element concentration The Cominco site is located 0.5 km from the smelter property and is subject to significant deposition of trace elements (Goodarzi et al., 2001; Chapter 2). The Thunder Road site is located 1.6 km from the smelter site, and is partially physically sheltered from deposition from the smelter by its topographic position above the valley, and an intervening ridge of rock. Deposition from the smelter is a major source of trace elemental input at this location (Goodarzi et al., 2003; Chapter 2), but to a lesser extent than at the Cominco site. The Champion Lakes sampling site is located approximately 13.5 km from the smelter, and is physiographically sheltered from smelter fall-out by the intervening mountains. However, there is some suspected smelter impact at this location (Goodarzi et al., 2003; Chapter2). Bulk trace element concentrations for the peat profiles are presented in Table 4-3. Concentrations of all the examined trace elements, with the exception of Ni, are highest near the smelter and decrease rapidly with radial distance. Concentration differentials between peat and nearby mineral soils indicate that some of the emitted trace elements are deposited as soluble aqueous species, or as readily soluble solids, which migrate from the mineral soil to the peat following deposition (Chapter 2). However, sequential leaching indicates that the recalcitrant material of the residual phase also contributes to the overall trace element concentration (Chapter 5). Sample Depth Sb As Cd Cu Pb Ni Zn (cm) ppm ppm ppm ppm ppm ppm ppm COMINCO' 0-1 126 78.5 61.7 196 3550 10.8 5910 1-2 141 97.8 65.2 223 3830 11.6 5600 2-3 128 153 53.8 215 3780 15.4 4230 3-4 142 116 60.3 227 3830 13.2 4730 4-5 121 164 47.1 214 3940 14.8 3570 17-20 85.0 247 60.1 226 5240 12.4 3040 THUNDER ROAD 0-1 34.1 60.0 119 82 1670 9.2 2730 1-2 37.7 64.4 105 103 2070 10.6 2270 2-3 33.0 62.0 139 84 1750 9.4 2900 3-4 37.6 65.4 134 96 1980 11 2590 5-6 32.5 67.5 104 92 1990 10.8 2330 11-14 34.9 59.0 120 96 1940 11 2300 CHAMPION LAKES 0-1 1.2 1.8 2.4 12 77 3 148 1-2 1.6 3.6 3.7 16 101.5 6 194 2-3 5.5 8.3 6.0 14 172 9.2 214 3-4 3.8 6.8 4.4 13 114.5 6 208 4-5 9.0 15.4 6.8 20 246 8.8 268 11-16 15.2 15.8 6.5 24 324 4.4 178 Table 4-3. Bulk concentrations of selected trace elements within the peat profiles. 4.4.2 Mineralogy 4.4.2.1 Cominco Site Mineralogy at the Cominco Site consists predominantly of quartz and sodic plagioclase feldspar, consistent with the underlying granodiorite bedrock (Table 4-4). The quartz content ranges from 33-63%, with the highest concentration occurring at the surface, a trend seen in most of the profiles examined. Feldspar values range from 10-35% for plagioclase and 0-31% for orthoclase. There is little or no clay, indicating a lack of weathering (supported by the thin to absent soils throughout the area). Phyllosilicates consist of mica (less than 5%) and chlorite (less than 2%), consistent with the underlying geology. Small amounts of amphibole are present throughout the profile, with a maximum of 5% at the profile base, but usually less than 2%. Additionally, a large amount of pyroxene is found in the upper portions of the profile (46% at 2-3 cm and 12% at 3-4 cm), but is absent from the remainder of the profile. 4.4.2.2 Thunder Road Site The mineralogy of the Thunder Road profile is similar to the Cominco profile, which is anticipated, as both sites overlie the Trail pluton, and are located approximately 1 km from one another. Quartz contents range from 49-62%, plagioclase contents range from 11-22%, and orthoclase ranges from 6-22%. Mica ranges from 2-8%, while chlorite is highly variable, from 0% to 14% in the 6-7 cm sample. No clays were detected in the profile. Amphiboles range from 2-6%. Anhydrite, which comprises 19% of the 8-11cm sample, may form from the dehydration of gypsum during the ashing process. The gypsum may have been present in the sampled peat, as gypsum is produced as a bi-product of the zinc operation, or it may have formed as a result of the oxidation of biogenic sulphur during ashing (Miller et al., 1979). 4.4.2.3 Champion Lakes Site The Champion Lakes mineralogy reflects the geogenic input from the underlying Elise Formation. The top of the peat profile contains amphibole (10-16%) and chlorite (2%), which diminish to 1-7% and less than 1%, respectively, from 8-16 cm. Plagioclase contents range from 14-35%, while no orthoclase was detected. Broad XRD peaks in the phyllosilicate positions suggest that most of the phyllosilicates are mixed layer clays rather than micas (2-6%, increasing downwards in the profile). The presence of calcite (13-38%, found from 8-16 cm) may be attributed to limestone xenoliths and calcite amygdules found within the flow breccias, or to calcite formed as a product of green schist facies metamorphism (Little, 1960). Anhydrite, probably formed from the dehydration of gypsum, occurs in the 6-7 cm sample. The gypsum may have formed from the oxidation of biogenic sulphur during the ashing process, or may form from gypsum from the smelter present in the original sample. Sample # Ash Quartz Feldspar Phylosilicates Amphi- Pyroxene Calcite Anhydrite % Plagioclase Orthoclase Mica Clay Chlorite bole Cominco Site 1-2cm 51.7 66. 16 13 3 0 0 2 0 0 0 2-3cm 63.2 34 10 6 2 0 2 1 46 0 0 3-4cm 62.4 37 35 9 3 0 1 2 12 0 0 4-5cm 66.2 60 21 11. 5 0 2 1 0 0 0 5-6cm 64 20 11 3 0 1 1 0 0 0 7-8cm 73.4 40 24 31 2 0 1 1 0 0 0 8-11cm 74.0 48 20 26 3 0 2 2 0 0 0 11-14cm 81.2 37 26 30 2 0 1 0 0 0 0 14-17cm 79.8 66 25 6 1 0 1 1 0 0 0 17-20cm 51.4 66 23 0 4 0 1. 6 0 0 0 Thunder Road Site 2-3cm 18.4 62 20 10 2 0 1 6 0 0 0 5-6cm 24.4 53 22 15 5 0 2 3 0 0 0 6-7cm 25.9 59 11 6 6 0 14 2 0 0 2 8-11cm 27.8 50 16 7 7 0 0 2 0 0 19 11-14cm 25.4 53 17 22 5 0 0 4 0 0 0 Champion Lakes Site 3-4cm 38.6 72 14 0 0 2 2 10 0 0 0 6-7cm 21.2 47 34 0 0 2 2 15 0 0 34 8-11cm 16.6 49 33 0 0 5 1 1 0 13 0 11-16cm 12.9 48 28 0 0 6 0 7 0 38 0 4.4.3 SEM-EDX investigation of peat ash The mineralogy as observed by SEM, is in general agreement with the XRD results. The most frequently observed minerals were quartz, K and Ca feldspar and Fe-silicates. Lead and Zn are the only trace elements that were frequently detected by EDX. Lead and Zn occur both in combination and separately and are commonly associated with S, Fe, and Mn, although no Fe-Mn oxides or sulphide phases were detected by XRD. These phases may be amorphous, and thus not detectable by XRD, or may be present in amounts below the detection limits of the XRD. Zinc is also associated with silicate minerals. Copper occurs only infrequently in small concentrations, while Sb, As, Ni, and Cd were not observed at all. Ti was frequently detected in particles from the Champion Lakes profile, but was seldom detected in the sites close to the smelter, consistent with the low Ti concentration (0.57%) in the Trail Pluton granodiorite (Sevigny, 1990; Table 4-1). Ti concentrations in the Pb and Zn concentrates processed by the smelter are typically in the range of 0.018% (Goodarzi, unpublished data) and so Ti may be assumed to be primarily of geogenic origin, and is not associated with the smelter emissions. Particles containing heavy metals are typically small and spherical and lack distinctive crystalline morphologies, suggesting a smelter origin. None of the particles observed were oxides with a distinctive O peak on the EDX spectra, which is characteristic of freshly emitted roasted smelter materials. The roasted particulates are more soluble than the ore concentrates, and are therefore likely to weather rapidly, particularly in an acidic environment such as a peatland. Particles with a morphology typical of a geogenic origin may be derived from the local rocks and soils, or may be fugitive dusts from ores transported in open railway cars or stockpiled in uncovered piles on the smelter property (Goodarzi et al., 2003). Geogenic particles and fugitive dust are commonly silicates and sulphides. Examples of geogenic and anthropogenic particles are illustrated in Figures 4-2 and 4-3, respectively. s 3 Zn 1 Zn i j l Ua L 0.0 5.0 10.0 kfiV 15.0 20.( Figure 4-2. Example of a geogenic particle (sphalerite) from the Champion Lakes sampling site. The number on the EDX spectra refers to the frame number on Table 4-10. J 4b Si iL z 0.0 5.0 10.0 15.0 20.0 kfiV \u00C2\u00A3 L i C i 4d Fe \ L z.n 0.0 5.0 10.0 15.0 20.0 kfiV Figure 4-3. Examples of heat-treated spherical or rounded metallic particles (4a and c) emitted from the smelter, observed in the Thunder Road 7-8 cm peat. Also present are a spherical silicate fly ash particle (4b) and a Zn-containg Fe-precipitate (4d). Numbers correspond to frame numbers in Table 4-9. 4.4.3.1 Cominco Site Particles commonly observed in the surface peats at the Cominco site which have a probable smelter origin are small (<2 pm), and rounded to subrounded, with low concentrations of Pb and Zn associated with Si, Al, Ca, K, S, P, Fe and Mn (Fig. 4-4; Table 4-5). Particles likely to be of geogenic or fugitive origin based on morphology are subangular to subrounded, larger than the smelter particles, and contain Zn with Si and Fe (Fig. 4-5). At 4-5 cm depth, particles containing Pb and Zn were identified as both anthropogenic (Fig. 4-6a) and geogenic (Fig. 4-7a) based on morphology (Table 4-6). With increasing peat depth (17-20 cm), Ti occurs more frequently, suggesting a geogenic origin for much of the examined particulate matter (Table 4-7). Particles containing Pb and Zn are typically more angular at this depth than those observed at the peat surface. Some of the Pb and Zn is associated with Fe-precipitates that are coating mineral surfaces (e.g. Fig. 4-8a). Small amounts of Cu were noted infrequently in association with Pb and Zn (Figs. 4-8, 4-9 a) in the Cominco 17-20 cm sample. 4.4.3.2 Thunder Road Spherical smelter-emitted particles containing Zn and Pb, with Cu, Fe, and Mn are common in the 0-1 cm sample (Fig. 4-10; Table 4-8). Iron precipitates, which contain elements scavenged from the peat pore water, frequently have high Zn concentrations (Fig. 4-11 c and d). Angular, geogenic particles of similar chemistry to the precipitates also contain Zn, possibly as a surficial coating (Fig. 4-1 la). Zn also occurs as a native element on the surface of a quartz particle (Fig. 4-12). Lead was not detected in this sample, other than in the round smelter-emitted particles (e.g. Fig. 4-10). Zinc occurs in a variety of associations in the 7-8 cm depth sample (Table 4-9): as an angular Zn-S-Si-Ca-Fe particle, probably of geogenic origin (Fig. 4-13); as an agglomerated particle, including a subangular native Zn particle (Fig. 4-14a); as a precipitate containing Zn, Si, Ca and Fe, (Fig. 4-14b,c); and as an Fe-Zn surface coating on a diatom (Fig. 4-14d). Spheroidal fly ash particles composed of Si-S-Ca-Fe were also observed (Fig. 4-13). The fly ash particles, identified based on the composition and morphology, are probably derived from coal burned at the smelter in the Pb-roasting operation, as there are no coal-fired power plants in the area. 4.4.3.3 Champion Lakes The particles examined in the Champion Lakes peat frequently contain Zn, with minor occurrences of Cu and Pb (Table 4-10). Many of these particles have angular morphologies, typical of a geogenic origin, such as the sphalerite particle in Fig. 4-2. Few particles with a composition or morphology suggestive of a smelter origin were detected within the Champion Lakes peat, with the exception of spherical silicate fly ash particles (Figs. 4-15 to 4-16). Spherical fly ash particles typically have a low density and are frequently hollow, and so are dispersed more widely in the environment than dense metallic particles. Many particles have higher Ti concentrations than were observed in the Cominco and Thunder Road sites (Fig. 4-15), in agreement with the higher Ti concentration associated with the background geochemistry at this site (Beddoe-Stephens and Lambert, 1981; Sevigny, 1990). Diatoms are abundant, in accordance with the lacustrine origin of the peat. 5a Si y \u00C2\u00AB Fe A 0.0 5.0 10.0 keV 15.0 20.0 5c Si J P b ^ s Ca M n F Zn 0.0 5.0 10.0 keV 15.0 20.0 Figure 4-4. Examples of rounded particles containing Pb and Zn present in the Cominco 1 -2 cm sample. Numbers on the EDX spectra refer to the Frame number on Table 4-5. Figure 4-5. Example of a subangular particle containing Zn from the Cominco 1-2 cm sample Number the EDX spectra refers to the Frame number on Table 4-5. Table 4-5. Summary of the observations from the Cominco 1-2 cm sample. \"Frame\" and \"spot\" refer to the numbers on the EDX spectra for the figures. Elements present in high concentrations are listed in bold face type. Frame Spot Size (Approx) Morphology Major Elements Trace Elements Comments 1 a 2 urn sub-rounded Al, Si, K, Ca, Fe minor Zn, Pb 2 a 1 urn sub-angular Si, K, Ca, Mn, S, Fe minor Zn geogenic? b 0.25 urn rounded Al, Si, K, Ca, P, S, Mn, Fe minor Zn geogenic? c 2 urn sub-angular Si, K, Ca, Mn, Fe minor Cr(7), Zn high amorphous content, interference 3 a 3 (am sub-rounded Si, K, Ca, P, S, Mn, Fe minor Pb, Zn slight O peak-may be altered smelter derived particle b 1 pm sub-rounded Si, K, Ca, S, Mn, Fe minor Pb, Zn c 3 tarn sub-rounded Mg, Si, Ca, S, Fe minor Zn d 1.5 urn sub-angular Mg, Si, Ca, S, Fe geogenic mineral particle 4 a 1.5 urn angular Si, Ca, P, S, Fe Pb, Sn, Cu? Zn? geogenic, based on morphology-fugitive dust? b <1 urn coating? Al, Si, K, Ca, S, Fe minor Zn, Pb(?) precipitate plus underlying mineral 5 a 2 urn rounded Al, Si, Ca, P, S, Fe Pb, minor Zn, slight O peak, probable smelter source b 1 urn rounded Al, Si, K, Ca, P, S, Fe Pb, minor Zn, slight O peak, probable smelter source c 1 |iim rounded Si, K, Ca, S, Mn, Fe minor Zn, Pb slight O peak, probable smelter source d 0.25 urn rounded Al, Si, K, Ca, S, Fe minor Zn, Pb slight O peak, probable smelter source e 0.25 urn rounded Al, Si, K, Ca, S, Fe minor Zn, Pb slight O peak, probable smelter source 6 a 2 fxm sub-rounded Al, Si, P, S, K, Ca, Mn, Fe Pb, minor Zn slight O peak, probable smelter source b 12 pm rounded Si, S, K, Ca, Fe fly ash c 0.5 pm rounded Si, S, K, Ca, Mn, Fe minor Zn, Pb slight O peak, probable smelter source 7 a 1 jam sub-angular Si, S, K, Ca, Fe Zn Possible geogenic source based on morphology b 0.25 urn sub-rounded Al, Si, S,K, Ca, Mn, Fe minor Pb? 8 a 2 urn Sub-angular Si, P, S, K, Ca, Mn, Fe Zn, Pb geogenic morphology b 6 pm Sub-rounded Si quartz particle 9 a 1 (am Rounded Al, Si, S,K, Ca, Mn, Fe Zn, Pb, Smelter source? b 1 urn Rounded Al, Si, S,K, Ca, Mn, Fe Zn, Pb, Smelter source? c matrix Si, S, K, Ca, Fe minor Zn, Pb geogenic mineral particle .10 a 1.5 |xm Sub-angular Si, S, K, Ca Fe minor Zn, Pb angular morphology, fugitive dust? b 0.25 nm Sub-rounded Si, S, Ca, Fe minor Zn, Pb c 0.5 |im Sub-rounded Si, S, Ca, Fe minor Zn, Pb 11 a 1.5 (iim Sub-rounded Si, S, K, Ca, Fe Pb, As(?) probable smelter particle b >15 nm sub-angular, matrix Mg, Al, Si, S, K, Ca, Fe geogenic mineral 12 a 0.5 (im sub-rounded Si, S, K, Ca, Fe minor Pb, Zn fugitive dust? 13 a 1 pm rounded Al, Si, S, K, Ca Fe minor Pb, Zn fugitive dust? b 1 pm rounded Al, Si, S, K, Ca Fe minor Pb fugitive dust? c 1 pm rounded Al, Si, S, K, Ca Fe minor Pb fugitive dust? 14 a 2.5 pm angular Mg, Si, S, K, Ca, Fe Zn fugitive dust b 2.5 pm rounded Al, Si, S, K, Ca, Fe minor Pb, Zn c 2.5 pm rounded Si, P, S, K, Ca Fe minor Pb, Zn 15 a 1 pm rounded Al, Si, S, K, Ca, Mn, Fe Pb, minor Zn slight 0 peak, smelter particle ? b 3 pm sub-angular Al, Si, S, K, Ca, Fe Pb, minor Zn fugitive dust? c 3 pm rounded Al, Si, S, K, Ca, Fe minor Pb, Zn 16 a 5 pm rounded Al, Si, S, K, Ca, Mn, Fe Pb, minor Zn Fe 3a Zn J is Zn U L 0.0 5.0 10.0 kfiV 15.0 20.0 3b Si Fe pSCa i W L M n / L 0.0 5.0 10.0 k f i V 15.0 20.0 Figure 4-6. Example of a rounded particle of anthropogenic origin containing Zn and Fe from the Cominco 4-5 cm sample (3a on Table 4-6). The geochemistry of examples of other particulate matter observed within the frame is indicated in spectras 3band 3c. Figure 4-7. Example of a subangular particle of geogenic origin containing Pb, from the Cominco 4-5 cm sample (4a on Table 4-6). Spectras 4b-d indicate the geochemistry of other observed particulates within the frame. Table 4-6. Summary of the observations from the Cominco 4-5 cm sample. \"Frame\" and \"spot\" refer to the numbers on the EDX spectra for the figures. Elements present in high concentrations are listed in bold face type Frame Spot Size (Approx) Morphology Major Elements Trace Elements Comments 1 a 4 pm Bulbous Si, K, Ca, Fe Sn b 4 pm Bulbous Si, K, Ca, Fe Sn 2 a 2 pm sub-rounded Al, Si, S, K, Ca, Ti, Mn, Fe Pb, minor Zn b 1.5pm sub-rounded Al, Si, P,S, K, Ca, Ti, Mn, Fe Pb, minor Zn c 5pm Surface coating Al, Si, S, K, Ca, Ti, Mn, Fe Pb, minor Zn precipitate d 10 pm sub-angular Al, Si, K, Ca, Fe Feldspar 3 a 3 pm rounded Al, Si, Ca, Fe Zn smelter-emitted b 0.5 pm rounded Al, Si, P, S, K, Ca, Mn, Fe Pb, Zn smelter-emitted? c 0.5 pm rounded Al, Si, P, S, K, Ca, Fe geogenic mineral matter 4 a 5 pm angular Al, Si, S, K, Ca, Ti, Mn, Fe Zn, Pb geogenic-fugitive dust? b 4.5 pm sub-angular Al, Si, P, S, K, Ca, Ti, Mn, Fe minor Pb geogenic mineral particle c 1.5 pm rounded Al, Si, S, K, Ca, Mn, Fe geogenic mineral particle d 8 pm angular Al, Si, S, K, Ca, Fe geogenic mineral particle 5 a 2 pm Coating? Si, S, K, Ca, Fe Pb Coating of (b)- PbS b 10 pm sub-rounded Si,K, Ca, Fe geogenic mineral particle 6 a 3 pm Sub-rounded Al, Si, S, K, Ca, Mn, Fe Pb, minor Zn smelter-emitted? b 0.5 pm rounded Al, Si, S, K, Ca, Fe minor Pb, Zn smelter-emitted? c 3 pm Sub-angular Al, Si, S, K, Ca, Fe minor Zn geogenic mineral particle 7 a 0.5 pm Sub-rounded Al, Si, K, Ca, Ti, Mn, Fe minor Cu, Zn b 2.5 pm Sub-rounded, Al, Si, K, Ca, Mn, Fe minor Zn, As smelter-emitted? c 2 pm Sub-rounded Al, Si, K, Ca, Mn, Fe Zn d 5 pm Sub-angular Al, Si, K, Ca, Mn Fe, minor Zn geogenic mineral particle Table 4-7 Summary of the observations from the Cominco 17-20 cm sample. \"Frame\" and \"spot\" refer to the numbers on the EDX spectra for the figures. Elements present in high concentrations are listed in bold face type. Frame Spot Size (Approx) Morphology Major Elements Trace Elements Comments 1 a 1 pm Sub-angular Al, Si, S, K, Ca, Ti, Fe Pb fugitive dust? b 5 pm Sub-rounded Al, Si, S, K, Ca, Ti, Fe minor Pb, Zn geogenic mineral particle c 0.25 pm Rounded Al, Si, S, K, Ca, Ti, Fe Pb, minor Zn fugitive dust? or smelter-emitted? d 15 pm Sub-angular Al, Si, S, K, Ca, Ti, Fe Pb, minor Zn geogenic mineral particle e 2 pm Sub-rounded Al, Si, S,K, Ca, Ti, Mn, Fe Pb, minor Zn, Cu geogenic mineral particle? 2 a 4 pm coating? Al, Si, S, K, Ca, Fe Pb, minor Zn, Cu precipitate? b 7 pm Sub-angular Al, Si, S, K, Ca, Fe minor Pb geogenic mineral particle c 9 pm Sub-angular Al, Si, S, K, Ca, Fe minor Pb geogenic mineral particle d 2.5 pm Rounded Si, S, K, Ca, Fe minor Pb? geogenic mineral particle e 4 pm Sub-angular Al, Si, S, K, Ca, Fe minor Pb? geogenic mineral particle 3 a 0.25 pm coating? Al, Si, S, K, Ca, Fe Pb, As precipitate PbS? b 2 pm Sub-rounded Al, Si, S, K, Ca, Ti, Fe Pb, Zn mineral background of (a) c 6 pm Rounded, oval Al, Si, S, K, Ca, Fe geogenic mineral particle 4 a 2.5 pm Rounded Al, Si, S, K, Ca, Ti, Fe Pb, minor Zn, Cu fugitive dust? b 5pm Sub-angular Si, S, Ca, Fe quartz particle c 7 pm Sub-angular Al, Si, S, K, Ca, Ti, Fe Pb, minor Zn geogenic mineral particle 5 a 2 pm Rounded, Al, Si, S, K, Ca, Ti, Fe Pb, minor Zn b 1 pm Rounded Al, Si, S, K, Ca, Ti, Fe Pb, minor Zn c >10 pm Sub-angular Al, Si, K, Ca K-Feldspar particle d 0.5 pm Rounded Al, Si, S, K, Ca, Ti, Fe Pb, minor Zn 6 a 2 pm Sub-angular Al, Si, S, K, Ca, Ti, Fe Cu, Zn, Pb geogenic b 5 pm Sub-rounded Al, Si, S, K, Ca, Ti, Fe minor Zn geogenic mineral particle c 3 pm fluffy Al, Si, S, K, Ca, Fe Zn, Pb precipitate 7 a 1.5 pm Rounded Al, Si, S, K, Ca, Fe Pb, minor Zn geogenic fugitive dust? b 4 pm Rounded Al, Si, S, K, Ca, Fe mineral particle behind (a) c 12 pm Sub-angular Al, Si, S, K, Ca, Fe mineral particle Frame Spot Size (Appro x) Morphology Major Elements Trace Elements Comments 8 a 2 pm Rounded, fluffy Al, Si, S, K, Ca, Fe Pb, minor Zn geogenic fugitive dust? b 3 pm Sub-angular Al, Si, S, K, Ca, Fe minor Pb, Zn mineral particle c 1 pm Sub-angular Al, Si, S, K, Ca, Fe minor Pb, Zn geogenic fugitive dust? 9 a 4 pm Sub-rounded Ca, Fe Cu, Zn precipitate b 20 pm Sub-angular Al, Si, S, K, Ca, Ti, Fe minor Cu, Zn, Pb mineral particle with amorphous coating? c 20 pm Sub-angular Al, Si, S, K, Ca, Ti, Fe minor Cu, Zn, Pb mineral particle with amorphous coating? Figure 4-8. Fe-Zn-Cu precipitate from the Cominco 17-20 cm sample (9a on Table 4-7). Examples of geogenic particles are also pictured (9b and c). Si 6a Pb S b lr Fe J L C u Z n 0.0 5.0 10.0 15.0 keV 20.0 Si 6c J C a BUL 0.0 5.0 10.0 keV 15.0 20.0 Figure 4-9. Geogenic particle containing Pb, from the Cominco 17-20 cm sample (6a on Table 4-7). The EDX spectra of other particulate matter observed within the frame are also presented (6b and c) Table 4-8 Summary of the observations from the Thunder Road 0-1 cm sample. \"Frame\" and \"spot\" refer to the numbers on the EDX spectra for the figures. Elements present in high concentrations are listed in bold face type. Frame Spot Size (Approx) Morphology Major Elements Trace Elements Comments 1 1b 6 pm spherical Ca, Mn, Fe Cu, Zn, Pb smelter-emitted particle 3 a 12 pm angular Si, S, K, Ca, Fe Zn mineral particle, Fe-Zn coating? b >50 pm angular Si, S,K, Ca, Fe feldspar c 1 pm agglomeration Si, S, K, Ca, Fe Zn precipitate? ZnS d <1 pm agglomeration Si, S, K, Ca, Fe Zn precipitate? ZnS 4 a 2.5 pm Sub-rounded Si, S, K, Ca, Fe Zn native Zn? b >50 pm angular Si, S, K, Ca, Fe mineral particle behind (a) 5 a 2 pm fluffy Si, S,K, Ca, Fe Zn native Zn? from smelter b 30 pm Subangular Si, S, K, Ca quartz particle behind (a) 1 n 1 \ 1 ^ Pb Mm Cu A t\ L ^ P b C a J i J U ^ W l 0.0 5.0 10.0 15.0 20.0 keV Figure 4-10. Spherical metal enriched particle emitted from the smelter, from the Thunder Road 0-1 cm sample (4a on Table 4-8). 1 Fe C Si b 3b Fe L..L ... 0.0 5.0 10.0 15.0 20.0 keV c I > l l 3c Zn i . 0.0 5.0 10.0 kPV 15.0 20.0 Ca 3d Si S i l l Zn \u00E2\u0080\u0094 A. \u00E2\u0080\u0094 0.0 5.0 10.0 kfiV 15.0 20.0 Figure 4-11. Examples of Zn-containing particles from the Thunder Road 0-1 cm sample, a.: weathered geogenic Zn sulphide mineral, c and d: Fe-Zn precipitates (frame 3 on Table 4-8). An example of the geochemistry of other particulate material observed within the frame is illustrated by spectra b. i ^ J / / 2|jm Figure 4-12. Example of native Zn particle from the Thunder Road 0-1 cm sample (Frame 5, Spot a on Table 4-8), with a quartz particle (b). Table 4-9 Summary of the observations from the Thunder Road 7-8 cm sample. \"Frame\" and \"spot\" refer to the numbers on the EDX spectra for the figures. Elements present in high concentrations are listed in bold face type. Frame Spot Size (Approx) Morphology Major Elements Trace Elements Comments 2 a 3 pm sub-angular Si, S, K, Ca, Fe Cu, Zn geogenic fugitive particle b spherical Si, S, Ca, Fe fly ash 3 a <1 pm sub-angular Si, Ca, Fe Cu, Zn native Zn-fugitive? b 5 pm fluffy agglomeration Si, S, K, Ca, Fe Zn precipitate, amorphous c 0.25 pm fluffy agglomeration Si, S, K, Ca, Fe Cu, Zn precipitate, amorphous d 5 pm diatom Si, S, K, Ca, Fe Zn diatom, possible surface ZnS precipitate 4 a 1 pm spheroid Si, S, K, Ca, Fe Zn smelter-emitted particle b 5 pm spheroid Si, S, K, Ca, Fe fly ash c <1 pm sub-angular Si, S, K, Ca, Fe minor Zn fugitive dust? d <1 pm fluffy Si, S, K, Ca, Fe minor Zn precipitate y Ca 2 a 0.0 5.0 10.0 15.0 20.0 keV Figure 4-13. Angular geogenic Zn-rich particle (a) and a spheroidal fly ash particle from the Thunder Road 7-8 cm sample (Frame 2 on Table 4-9). 3a Z n si c.a \u00C2\u00A3Ma ).0 5.0 10.0 keV 15.0 20.0 Figure 4-14. Agglomeration of Zn rich particles, including a subangular native Zn particle (a), Zn-rich precipitates (b and c) and (d) a diatom with Zn precipitated on the surface from the Thunder Road 17-20 cm sample (Frame 3 on Table 4-9). Table 4-10. Summary of the observations from the Champion Lakes 3-4 cm sample. \"Frame\" and \"spot\" refer to the numbers on the EDX spectra for the figures. Elements present in high concentrations are listed in bold face type. Frame Spot Size (Approx) Morphology Major Elements Trace Elements Comments 1 a 18 pm Sub-angular Al, Si, S K, Ca, Ti, Fe mineral particle b 3 pm Sub-angular Si, Ca quartz c 15 pm Spherical Si, Ca fly ash 2 a 30 pm Angular Al, Si, Ca plagioclae particle b 40 pm Angular Al, Si, K, Ca, Fe feldspar particle 3 a 50 pm Angular Si, S, Zn geogenic sphalerite 4 a 10 pm Spherical Al, Si, K, Ca fly ash 5 a 5 pm Sub-angular Al, Si, Ca, Ti mineral particle 6 a 7 pm Spherical Si, Ca fly ash b 14 pm Sub-angular Al, Si, P, S, Ca, Fe mineral particle c 2 pm Sub-angular Si, Ca, Fe quartz particle d 4 pm Sub-rounded Al, Si, S, K, Ca, Fe mineral particle e 4 pm Sub-rounded Al, Si, S, Ca, Ti, Fe mineral particle 7 a 4 pm Angular Al, Si, K, Ca, Ti mineral particle 8 a 8 pm Sub-angular Al, Si, K, Ca, Fe quartz particle 9 a 4 pm Sub-angular Si, S, Ca, Fe Zn sphalerite particle Si 1 c u 0.0 5.0 10.0 keV 15.0 20.0 Figure 4-15. Diatom-rich ash material from the Champion Lakes 3-4 cm sample (e.g., b). Non-biogenic materials include an angular Ti-rich geogenic particle (a) and a glassy silicate fly ash particle with slight Ca enrichment.(c) (Frame 1 on Table 4-10). Si 6 a _ sJl_JLe 0.0 5.0 10.0 keV 15.0 20.0 1 3i 6 d ll L 0.0 5.0 10.0 15.0 20.0 keV S Ca I 6e J IfJl 0.0 5.0 10.0 keV 15.0 20.0 Figure 4-16. Geogenic particles containing Si, Ca, Fe, Al and S from the Champion Lakes 3-4 cm sample (spots a, c, d and e). Spot (b) is a glassy Si fly ash particle with slight S, Ca and Fe enrichment. (Frame 6 on Table 4-10). 4.5 Discussion 4.5.1 SEM-EDX Investigations of Smelter-Related Media The identification of particles found in the peat was aided by comparison to SEM-EDX investigations of other media associated with the smelter, including smelter wastes and feedstocks, particles captured by atmospheric deposition monitoring stations and stream sediments. Particulate matter within the peats has potentially undergone weathering and alteration in the environment. Comparisons with \"fresh\" smelter materials, with the sampling media from an atmospheric monitoring project (Goodarzi et al., 2003), and with geologic materials such as stream sediments provides insight into the changes that occur in the smelter emitted particles following their release into the environment. 4.5.1.1 Smelter Wastes Goodarzi et al. (unpublished report) investigated the chemical and microscopic properties of materials collected from the zinc baghouse facility at the Teck-Cominco smelter. The particulate material typically contains Pb and Zn, with the occasional occurrence of Cr, Ni, Cd, and As. The trace elements had several modes of occurrence: as silicates or alumino-silicates with or without Fe and/or Mn, as oxides, or as sulphides. Particles were typically small (less than 5 pm), and subangular to subrounded. 4.5.1.2 Moss Monitoring Stations A network of moss monitoring stations, installed to monitor the atmospheric deposition of elements in the area surrounding the smelter, was set up in 1997 (Goodarzi et al., 2001; 2003). The moss is changed every three months and so particles trapped in the matrix are usually freshly-emitted particulates that have undergone little weathering. Particles trapped by moss monitoring stations close to the smelter are often small and rounded or \"fluffy\" in morphology (Fig. 4-17). Fugitive dusts are generally angular and similar in chemistry to the ore (sulphides), while the particles emitted from the smelter are typically oxides, native elements or sulphates (Goodarzi et al., 2003). Few of the particles from the peat profiles that were identified as smelter-emitted had prominent oxygen peaks in their corresponding EDX spectrum, unlike the particles from the baghouse and the moss monitoring media. However, the lack of metal oxide particles within the peat should not be taken as evidence that the high trace element concentrations within the Cominco and Thunder Road profiles are due exclusively to fugitive and geogenic sources. The soluble oxide particles are likely to be rapidly altered following emission to the environment. The pronounced preferential sequestration of trace elements in the peats relative to the mineral soils that occurs near the smelter (Chapter 2) illustrates that a large proportion of the trace elements emitted by the smelter are mobilised following deposition. 4.5.1.3 Stream Sediments Stream sediments from the area surrounding the smelter were examined (Goodarzi et al., unpublished report). The morphology of particles depended on source: particles attributed to smelting activities were usually less than 5 pm in diameter and had a rounded or \"fluffy\" morphology, while particles ascribed to fugitive sources (dust from unprocessed ore) were more angular and variable in size. Geogenic particles commonly consisted of quartz, microcline, albite, amphibole, mica, clinochlore and smectite. 4.5.2 Environmental Significance The source of trace elements in mining or smelting areas may have an control the potential for health impacts on the inhabitants of the surrounding area. An SEM-EDX examination of particulate matter may be helpful in determining the potential bioavailability of trace elements. Rieuwerts et al. (2000) found that Pb in garden soil from mining areas (sulphides) is less bioavailable than Pb in garden soil from the area surrounding a smelter (Pb-oxides and sulphates). Significantly more Pb was found in the house dust in the area surrounding the smelter, and blood-Pb levels were correspondingly higher. For this reason, geogenic and fugitive dust sources of Pb and Zn are of less concern from a health perspective than the metal oxides and sulphates emitted by a smelter. Furthermore, the size of the metal-containing particles may have important health and environmental implications. The fine particles (<10 pm) emitted by the smelter are more likely to be inhaled and become lodged deep within the lungs. Small particles are more likely to \"be widely dispersed in the environment by prevailing winds, and are more rapidly weathered than large particles due to a higher relative surface area. For these reasons, heat treated smelter-emitted particles represent a greater potential threat to the local environment than the fugitive dust and geogenic particles. ZnS 3.5*2.8 pm 0.8\1 mil \ V 1\1.5 pm (Columbia Gardens) Figure 4-17. Examples of particulate matter captured by the moss-monitoring stations in the Trail area. a. Geogenic quartz particle, b. Rounded and \"fluffy\" PbO particles formed by thermal alteration in the smelter, and angular ZnS particles from fugitive emissions, c. Angular ZnS particles derived from fugitive dust, collected near an ore and slag storage facility. From Goodarzi et al., 2003. 4.6 Conclusions An examination of the morphology and elemental composition of particles found in peat ash from the vicinity of a Pb-Zn smelter is a useful method for assessing the sources of trace element pollution within the environment. The small, rounded Pb and Zn-containing particles found in the peats near the smelter were likely emitted from the smelter following roasting, while the more angular particles are likely fugitive dust from unprocessed stockpiled ores, or natural locally derived geogenic particles. These findings suggest that reducing dust during transport and storage of ores would be a valuable initiative in reducing the amount of metals released from the smelter operation, although these particulates may represent a less bioavailable source of trace elements than the processed particles. No oxides of Pb or Zn were detected in any of the peat samples examined, although they were observed in the moss monitoring sampling media. This suggests that these anthropogenic particles are subject to rapid weathering in the environment and are a major source of mobile and potentially bioavailable trace elements to the surrounding environment. The lack of anthropogenic particles containing Pb or Zn at the Champion Lakes site suggests that particulate deposition from the smelter is not a major source of trace elements at this location. Low density Si-rich fly ash was noted, indicating that deposition of smelter-derived material does occur in the Champion Lakes area to a small extent, and it is possible that trace elements are deposited in the area in non-particulate forms, for example, as dissolved species in precipitation. Moss monitoring studies (Goodarzi et al., 2001; 2003) and a peat trace element study (Chapter 2) indicate that there is possibly minor deposition of trace elements from the smelter at this location. 4.7 References Beddoe-Stephens, B. and. Lambert, R.St.J. 1981. Geochemical, mineralogical and isotopic data relating to the origin and tectonic setting of the Rossland volcanic rocks, southern British Columbia. Canadian Journal of Earth Sciences, 18: 858. Goodarzi, F., Sanei, H., and Duncan, W.F. 2003. Deposition of trace elements in the Trail region, British Columbia; an assessment of the environmental effect of a base metal smelter on land. Geological Survey of Canada Bulletin 573, 50 p. Goodarzi, R, Reyes, J. and Sanei, H. 2002. Concentrations of elements in the stream sediments in Trail, BC and the surrounding area and the natural background concentration. Unpublished report. Hall, G.E.M., Vaive, J.E. and MacLaurin, A.I. 1996. Analytical aspects of the application of sodium pyrophosphate reagent in the specific extraction of the labile organic compounds of humus and soils. Journal of Geochemical Exploration, 56: 23-36. Little, H.W. 1960. Nelson Map-Area, West Half, British Columbia (82 F Wl/2). Geological Survey of Canada Memoir 308. 205p. Little, H.W. 1982. Geology of the Rossland-Trail Map-Area, British Columbia. Geological Survey of Canada Paper 79-26, 38p. Miller, R.N., Yarzab, R.F. and Given, P.H. 1979. Determination of the mineral-matter contents of coals by low-temperature ashing. Fuel, 58: 4-10. Sevigny, J.H. 1990. Geochemistry of the Jurassic Nelson plutonic suite, southeastern British Columbia. In : Project Lithoprobe; southern Canadian Cordillera transect workshop. Lithoprobe Report 11, pp. 41-52. Chapter 5 Determination of the mode of occurrence of trace elements in peats and soils from the vicinity of a Pb-Zn smelter using a sequential extraction procedure 5.1 Introduction A common approach to determining the potential environmental impact of trace elements is by way of sequential extraction. Sequential extraction procedures differentiate between operationally-defined phases in which the trace elements are present within the sediment. By determining the concentration of trace elements within each phase, the mobility and bioavailability, and thus, potential environmental impact, can be inferred. The mode of occurrence can also be used to infer the source of the trace elements. The procedure can also be used to differentiate between anthropogenic and geogenically-sourced elements to some extent. The concept behind the use of sequential extractions is to treat a sample of sediment with a series of increasingly harsh reagents which have been experimentally shown to be selective to a particular phase (e.g., Tessier et al., 1979). Phases typically extracted may include: exchangeable (adsorbed to clays and organic matter); associated with carbonates; associated with reducible iron and manganese oxides, hydroxides and oxy-hydroxides; associated with organic matter; associated with sulphides; and residual elements within the crystal lattice of mineral matter (e.g. Tessier et al., 1979). This study examines the mode of occurrence of selected trace elements (Sb, As, Cd, Cu, Pb, Ni and Zn) in profiles of peat and organic sediments from the area surrounding a lead-zinc smelter. The capacity for peats to retain trace elements is of interest in studies in which the objective is to determine the fate of trace elements in the environment. This study builds on earlier work in which: the total trace elemental content of peat profiles in the vicinity of the smelter was examined and discussed with reference to measurements of atmospherically deposited trace elements and trace element concentrations in nearby mineral soils (Chapter 2); geochemical tracer methods were applied to the peats in order to determine if the relative impact of the smelter on the trace elemental composition of the peats could be deteremined by geochemistry (Chapter 3); peat ash materials were examined by SEM-EDX and compared to fresh smelter wastes and feedstocks (Chapter 4): and the peats were characterised using organic petrographic methods (Chapter 6). The results of previous investigations are summarised briefly in the results section. 5.2 Study Area The Teck-Cominco smelter in Trail, British Columbia has been in operation since 1896. The smelter's primary products are Pb and Zn, but Ag, Au, Cd, Bi, In, Ge concentrate, GeC>2, Q 1 S O 4 , CuAsO and sulphur products are also produced as by-products. Ammonium nitrate fertilizers are also produced by Cominco in a separate plant located near the smelter. Improvements in technology and operating practices have reduced trace element emissions from the smelter in recent years, however, high concentrations of trace elements measured in peats from the surrounding area record the cumulative impact of a century of operation (Chapter 2). 5.3 Sampling Locations Sampling sites were selected in order to obtain a representation of the lateral distribution of trace elements in the area surrounding the point sources. Considerations for site selection included the distance and direction from the smelter, bedrock geology, and availability of organic sediments. The latter posed a particular problem in the Trail area, as peatlands in that region are few in number. Trail, British Columbia (Fig. 5-1) is situated in the Columbia River Valley, which bisects the sampling area. The bedrock in the area consists mainly of Upper Jurassic plutonic rocks (the Nelson Intrusives), and Lower Jurassic metavolcanic and metasedimentary rocks (the Elise Formation; Little, 1982; Hoy and Andrew, 1991). 5.3.1 Cominco Site The site consists of a series of small fens. The underlying bedrock is the Trail Pluton, consisting predominantly of granodiorite, with quartz diorite and diorite at the margins (Little, 1982; Simony, 1979; Fig. 5-1). Vegetation consists of Typha latifolia (common cattail), with Epilobium ciliatum (purple leafed willow herb), Carex urticulata (beaked sedge), Equisetum palustre (marsh horsetail), and Deschampsia cespitosa (tufted hairgrass). The pH of the peat, measured in the field, ranged from 5.3 at the surface to 5.6 in the underlying mineral sediment, and the pore water had a pH of 5.7. At the time of sampling, the entire peat profile was water saturated. It was noted in the sampling pit that features associated with reducing conditions, such as gleying, were not present in the uppermost 15 cm of peat, hence it is assumed that the top 15 cm are at least intermittently aerobic. This site is located approximately 0.5 km from the smelter and is known to be 117*46* 117\u00C2\u00B034' 49\u00C2\u00B015* QUATERNARY UnconsoBdated sediments; till, sand gravel, silt JURASSIC/CRETACEOUS NELSON INTRUSIONS: granodiorite; minor quartz diorite and diorite H ROSSLAND MONZONITE: biotite-hornblende-augite monzonite, mainly medium grained JURASSIC EUSE FORMATION: flow breccia, massive andesites and basalts, agglomerate, tuff, breccia, laminated siltstone MOUNT ROBERTS FORMATION: black siltstone and argillaceous - j quartette, slate, yeywacke, chert, pebble conglomerate, lava; Kmestone TRAIL GNEISS: amphibolite and grey biotite gneiss, hornblende gneiss, mica schist, aplite and Kilometres 1 El Figure 5-1. Geological map of the Trail, British Columbia area, with sampling locations for peats and stream sediments indicated. subject to heavy impact from the smelter (Goodarzi et al., 2003; Chapter 2). 5.3.2 Thunder Road Site The site consists of a group of small fens parallel to a small gravel road, with a high ridge of granodiorite behind them. This site is also located on the Trail Pluton (Little, 1982; Fig. 5-1), and has granodiorite bedrock similar to that described for the Cominco site. Vegetation is also similar to the Cominco site, with Typha latifolia, Pinus sp. (pine), Betula sp. (birch), Epilobium ciliatium, Equisetum palustre, Carex utriculata and Deschampsia cespitosa. The watertable was approximately 10 cm below the peat surface at the time of sampling. The pH ranged between 5.0 (surface) to 5.4 (mineral sediment), and the pore water pH was 5.7. This site is located approximately 1.5 km from the smelter and is subject to significant trace element deposition from the smelter, although to a lesser extent than the Cominco site, due to the larger intervening radial distance and partial topographic sheltering (Goodarzi et al., 2003; Chapter 2). The site is also subject to input from a fertiliser factory, which currently produces N-fertiliser, but previously produced phosphate and potassium fertilisers as well (W. Duncan, personal communication). 5.3.3 Champion Lakes Provincial Park The bedrock in the Champion Lakes area is the Lower Jurassic Elise Formation (Fig. 5-1), which is characterized by flow breccia, massive lava, agglomerate, volcanic breccia, tuff, tuffaceous conglomerate, andesite, basalt and augite porphyry, metamorphosed to green schist facies. Limestone xenoliths and calcite amygdules are found within the mafic flows. Clasts from the tuffaceous conglomerates are commonly limestones derived from the underlying Mount Roberts Formation (Little, 1982; Hoy and Andrew, 1991). The Elise Formation hosts most of the gold and copper (pyrrhotite with chalcopyrite) vein deposits of the Rossland area (Hoy and Andrew, 1991). Lead, zinc and silver vein deposits are also associated with the contact of the Elise and the overlying Hall Formation. Associated minerals include sphalerite, galena, arsenopyrite, pyrite, chalcopyrite and boulangerite. This site is located in a provincial park, approximately 13.5 km from the smelter. The site is sheltered from deposition from the smelter due to the intervening mountainous topography, and due to the fact that the prevailing winds are generally from the northwest (Goodarzi et al., 2003). Peat was sampled from a marsh surrounding the lake. The peat-forming vegetation consists mainly of Carex sp., with Nuphar lutea (cow lily) and several species of grasses. The water table was approximately 8 cm below the peat surface at the time of sampling. The peat pH was 6.5 at the surface and at 15 cm depth, while the pore water had a pH of 6.4. 5.4 Methodology Peats were sampled by means of digging pits with a stainless steel shovel, and cutting blocks of peat from the pit wall. The peat blocks were immediately sealed in acid-washed plastic freezer bags and refrigerated within 24 hours. Measurements of pH were taken in the field using a portable pH meter. Peats were subsampled in a clean room, using an acid-washed plastic knife. Samples for analysis were removed from the interior of the peat block, so as to use material that was uncontaminated by the sampling procedure. Samples were selected to include peats from a range of depths within each profile. The peats were subsequently freeze-dried, and ground to a fine powder with an agate mill that was thoroughly acid-rinsed and washed with deionized water between each sample. Organic carbon and sulphur were determined using a LECO-SC444 carbon and sulphur analyser. Samples were treated with 10% HC1 for 24 hours to remove carbonate, and were subsequently rinsed with distilled water and dried at 80\u00C2\u00B0C overnight. The sequential extraction procedure used in this research was developed from methods described in Tessier et al. (1979), Hall et al. (1996a,b), Land et al. (1999), Clark et al. (1997), and Kersten and Forstner (1987). After reviewing the literature and considering the type of sediment involved and the objectives of the study, the following procedure was developed: 1 g of sample was added to acid washed Nalgene \u00C2\u00AE centrifuge tubes. Water soluble/exchangeable phase extraction: Due to very low recoveries in an initial batch of sequential leaching, the water soluble fraction was pooled with the exchangeable phase. The water soluble fraction was extracted by adding 25 ml of distilled deionised water to each sample. The samples were shaken for 1 hour, and were then centrifuged for 15 minutes at 10000 rpm. The samples were then rinsed with an additional 10 ml of deionized distilled water, shaken briefly, centrifuged, and decanted. The decanted supernatant was then centrifuged at 15000 rpm for 30 minutes to separate any suspended solids that were accidentally decanted earlier.; The supernatant was decanted into an acid washed Nalgene\u00C2\u00AE HDPE sample bottle. The exchangeable fraction was extracted by adding 25 ml of 1 M MgCl2 solution to each sample. The samples were shaken for one hour and were subsequently centrifuged, rinsed and decanted in the manner described for the water soluble fraction. Carbonate phase extraction: 25 ml of 1M Na-CH3COOH, adjusted to pH 5 with glacial acetic acid, was added to each sample. The samples were shaken for two hours, and centrifuged and rinsed with water as described above. Iron and Manganese oxide, hydroxide and oxy-hydroxides (reducible Fe and Mn) phase extraction: 25 ml of 0.1 M NH2OH HC1 was added to each sample. The samples were heated in a 80\u00C2\u00B0C water bath for 2 hours, then were shaken for an additional 2 hours. Subsequently, the samples were centrifuged and rinsed in the manner described above. Organically-chelated ions: The samples were transferred to 250 ml beakers. 100 ml of 1M NaP207 solution was added to each sample. The sample was shaken for one hour, centrifuged and decanted. The procedure was repeated. The samples were subsequently rinsed with deionized distilled water, as with the other extraction steps. Sulphide phase extraction: 50 ml of 30% H2O2 was added to each sample. The reaction is quite vigorous (effervescent) when the samples contain a large amount of organic matter, resulting in almost instantaneous \"bubbling over\" when the procedure developed for mineral soils and sediments was followed (heating to 80\u00C2\u00B0C for two hours). For this reason, this extraction had to be performed in a number of steps and over a longer period of time than the peroxide extractions described in the literature for non-organic sediments. The samples were gently swirled by hand to mix, and were then allowed to settle. When bubbling had ceased, the samples were shaken more vigorously, then allowed to settle. The samples were subsequently heated in a 40\u00C2\u00B0C water bath. The samples were removed as soon as the bubbling became vigorous, and were allowed to cool. This procedure continued, until the reaction rate became observably slower. Throughout this procedure, the hydrogen peroxide evaporates, and thus further additions of H2O2 are necessary. When the reaction rate at 40\u00C2\u00B0C slowed, the samples were heated to 80\u00C2\u00B0C. The samples were heated continuously, with periodic cooling to prevent boiling over as necessary, with further additions of H2O2 until all bubbling had ceased (this procedure may take several days, depending on the organic content of the samples). The samples were then centrifuged and rinsed as described previously. Residual fraction: The remaining residue from each sample was treated with 10 ml of H F / H N O 3 / H C I solution (5:3:1 ratio), in a Teflon microwave digestion vessel. Microwave digestion followed the manufacturer's recommendations for soils (CEM Technologies, personal communication, 2001). Samples were digested until all residue was observed to be dissolved, or until no further dissolution appeared to be occurring. Total concentrations were determined using microwave digestion of homogenised whole samples in triple acid solution similar to the digestion of the residual fraction, following a pre-digestion stage in open vessels to allow volatile gasses evolved from the decomposition of organic matter to be released prior to sealing in the microwave vessels. Extractions were performed in sets of 7 with one blank per extraction step per set. Following extraction, all extracts were heated to dryness in a deionised-distilled water bath and redissolved in 20 ml of 2% high purity nitric acid (250 ml in the case of the organic chelate fraction). ICP-MS analysis was performed with a Ru internal standard and a high purity Seastar \u00C2\u00AE nitric acid matrix. Instrument calibration was performed with a multi-element standard solution. Replicate analyses, at both equal and variable dilutions, analysis of two isotopes of Ni, Cu, Zn, Sb and Cd, and blanks were used as a check on data reliability. The exchangeable, carbonate and organic chelate fractions were analysed using standard additions to a sample of the blank in order to account for matrix interference effects. When the sum of the concentrations from the sequential leaching procedure is compared with the total digestion concentration, the percent error is variable. Percent error for the three profiles averages +/-35% but ranges between +/-0.7% to 100% for individual samples. This may be due to sample heterogeneity or to cumulative error associated with each leaching step. However, correlation coefficients for the summed concentration versus the total concentration for each data set are high (0.71 for Thunder Road, 0.91 for Cominco and 0.96 for Champion Lakes), indicating that the overall trends in the total concentration are reflected in the summed concentrations. While sequential extraction methods have been shown to be helpful, they are by no means infallible (Kersten and Forstner, 1987; Martin et al., 1987). The results of each extraction step can be considered to be operationally-defined, rather than absolute, since extraction may be incomplete due to incomplete solublisation or to readsorption, or may inadvertently release metals associated with another fraction. Individual elements may respond differently to the extracting solution (e.g. Dominik et al., 1983; Luksiene and Shvedov, 1985). A major problem encountered with the use of sequential extractions with anaerobic sediments such as peats is that changes in phase association may occur when the samples are oxidised during sampling, storage or drying. Forstner (1987) and Kersten and Forstner (1987) examined this problem experimentally, and found that the majority of the oxidative transfer of trace elements occurs between the organic and the reducible iron phases. For this reason, it should be assumed that at least some of the trace elements measured in the reducible iron phase originated in the organic matter phase. However, knowledge of the potential errors associated with the use of these procedures enables data to be discussed in a useful way. 5.5 Results 5.5.1 Summary of Results from Previous Studies Chapter 2 examines the total concentration of selected trace elements of the peat profiles in the vicinity of the smelter, and discusses these concentrations with reference to measurements of atmospherically deposited trace metals and trace metal concentrations in mineral soils near the peats and from background locations. Peats closest to the smelter have elevated concentrations of Pb, Zn, Sb, As, Cd, and Cu, which decrease with increasing radial distance from the smelter. The peats are enriched in the aforementioned elements relative to the mineral soils, and the extent of enrichment is relative to the extent of element loading at the site. This finding indicates that the elements deposited on the surface of the soil from atmospheric fallout are subsequently solubilised and transported from the soil to the peat, where they are sequestered as a result of the geochemical conditions found within the peat. Nickel concentrations, however, did not decrease with increasing distance from the smelter, nor was Ni relatively enriched in the peat relative to the mineral soils. Based on these findings, it was concluded that Ni was largely of geogenic origin. Selected samples of the peat ash material examined by SEM-EDX were found to have trace elements present in several elemental associations (Chapter 4). Heat-treated rounded particulate matter from the smelter was noted to contain Pb and/or Zn in association with Si, Al, and Fe. Angular particles of sulphide minerals with high concentrations of Pb or Zn were determined to be either fugitive emissions from the smelter operation or detrital minerals. Both particle types occurred in the peats from the Cominco and Thunder Road sites, but were not detected in the Champion Lakes site. The only evidence of anthropogenic impact in the Champion Lakes peat was the presence of spherical fly ash particles composed of Si-rich glassy material. Zn was also noted in geogenic particles. The organic petrographic composition of the peats was determined by point counting in reflected white and blue light (Chapter 6). While the practice of using the maceral composition to classify the depositional environment (e.g. swamp, bog, marsh or fen) has come under criticism, the organic petrographic characteristics are useful in determining the past and present conditions of early diagenesis within the peat (e.g. Wiist et al., 2001). The peat from the Cominco profile was well humified with abundant fungi, indicating that conditions within this peat are frequently aerobic. The Thunder Road peat was better preserved, with higher contents of textinite (intact cell structure) and texto-ulminite (anaerobic gelification) indicating less oxidizing conditions. The Champion Lakes peat maceral composition is indicative of a relatively well preserved peat subject to some oxidation. 5.5.2 Sequential Leaching Results The mode of occurrence of elements is largely a function of the Eh and pH conditions within the peat, and the source of the trace elements. While there is a great deal of variability in behaviour between the elements, generally, the reducible fraction is more significant as a sink for elements in the uppermost, more aerobic portion of the profile, while the organic and residual fractions are of greater importance with increasing depth. 5.5.2.1 Cominco Site Total concentration trends follow a similar pattern for Sb, As, Cd, Cu, Pb and Zn (Fig. 5-2). The concentrations at the peat surface are relatively high, followed by a zone of lower concentrations in the 8-11 cm sample. Concentrations for the aforementioned elements increase sharply in the 14-17 cm sample, and decrease steadily in the deeper samples. Concentrations in the mineral basal sediment underlying the peat profile increase sharply relative to the overlying peat, they are low relative to the concentrations measured in the upper portion of the peat profile. Concentrations of Ni are relatively consistent throughout the profile. Organic carbon ranges from 20.9% at the surface to 2.9% in the basal mineral sediment, and total sulphur ranges from 0.04-0.32% (Table 5-1). The exchangeable fraction is an important sink for Ni, As, Zn, Cd and Pb (Figs. 5-3 and 5-4). The relative importance of this sink increases with profile depth for Ni, As and Pb, while the Zn exchangeable fraction is consistent throughout the profile depth (3.6-10.6%), and the Cd exchangeable fraction fluctuates throughout the profile (7.5-44.6%). The carbonate fraction is a significant sink for Pb (8.6-19.5%) and to a lesser extent, Zn (1-7%) and Cd (2-7%), while generally contributing less than 4.5 % of the total element concentration for Ni, Cu, As and Sb. The relative proportion of carbonate-associated elements decreases with increasing peat depth for Zn and Cd and to a lesser extent for Pb, although the absolute concentration follows overall concentration trends, with a spike in the 14-17 cm sample. The reducible Fe and Mn fraction is the major sink for Pb, Zn, As and Cd (19-72%) throughout the profile depth, and a major sink for Ni, Cu and Sb in selected samples. There is a relative and absolute concentration spike of reducible-fraction associated elements in the 14-17 cm sample, coinciding with the increase in total concentrations. Typically <20% of the total Pb, Sb, Cu and As occur within the organic chelate fraction, and the highest relative and absolute concentrations coincide with the total concentration spike at 14-17 cm depth. The sulphide fraction represents approximately 2-4% of the As, Pb, Zn and Cu, and 7-10% of the Sb and Cu at the surface of the peat. The relative percentage of elements extracted from the sulphide phase decreases with increasing depth to the basal mineral sediment. The relative percentage of sulphide-associated elements increases abruptly in the basal mineral sediment for all the examined elements. The sulphide fraction represents 8% (Cd) to 48% (Cu) of the total element concentration in the basal mineral sediment, while the peat immediately above (32-36 cm) contains little or no Concentration (ppm) M O) CO O O O o O O O O O Concentration (ppm) Pb Zn Figure 5-2. Total element concentrations within the Cominco profile. BSed = basal mineral sediment. Sample % Sulfur %Carbon Cominco 2-3 0.29 20.88 Cominco 3-4 0.27 18.28 Cominco 8-11 0.21 13.37 Cominco 14-17 0.32 12.31 Cominco 32-36 0.01 0.41 Cominco Basal Sediment 0.04 2.91 Cominco Mineral Topsoil 0.05 6.44 Rossland Background Soil 0.00 0.05 Thunder Road 0-1 0.33 31.03 Thunder Road 3-4 0.36 28.62 Thunder 2-3 0.33 30.27 Thunder 5-6 0.35 26.74 Thunder Road 17-20 0.07 4.45 Thunder Road Basal 0.01 0.52 Sediment Champion Lakes 2-3 0.97 31.96 Champion Lakes 3-4 0.85 29.67 Champion Lakes 4-5 0.86 34.24 Champion Lakes 35-36 1.52 39.78 Champion Mineral soil 0.06 13.50 Table 5-1. Organic carbon and total sulphur concentrations of selected samples. sulphide-associated trace elements. The residual phase is the major mode of occurrence for Ni, Cu and Sb. The relative proportion of Zn, Cd and Pb associated with the residual phase is variable throughout the depth of the profile, but is negligible in the basal mineral sediment, (<3%). Trace elements associated with the silicate particulates emitted by the smelter are most likely extracted in the residual fraction, and so the residual fraction is not necessarily exclusively representative of geogenic materials. 5.5.2.2 Thunder Road Total concentrations of trace elements are lower at the Thunder Road site than at the Cominco site (Fig. 5-5). Concentrations of Pb and Zn are highest at the surface of the peat and decrease with depth, as do concentrations of As, Sb and Cd, although to a lesser relative extent. Concentrations of Cu and Ni increase with increasing depth in the peat. All elements are present in lower concentrations in the basal mineral sediment than in the JQ D. O \u00E2\u0080\u00A2o o O IO o 10 r- r CN N o J2 cn ro CO <*> a) W to S CD CO in o 10 \u00E2\u0080\u00A2\u00C2\u00AB- CM CM 8 / \ / \ / X \u00E2\u0080\u00A2 .,\u00E2\u0080\u00A2\u00C2\u00AB : i . \u00E2\u0080\u00A2 t - ,. '^rr^t I . 10 o w ^ CM CM s J2 \"5 c/J (5 \u00C2\u00AB n ^ m CD in < w o m o m o (\u00C2\u00A3-ornco T-T-CMCM tocoojig^ Q-0 .2 a)Oc/D_ c5\u00E2\u0084\u00A2-- ro to o \u00E2\u0080\u00A2C-Q.^ as ca-2 O J^ rj) rn W X (0 O c ' c '\u00C2\u00A9 UJOQTOOQi Mil sample depth (cm) Figure 5-3. Absolute concentrations (in ppm) for sequentially extracted fractions in the Cominco profile, including the basal mineral sediment (BSed). Concentrations for the Cominco mineral soil (MS) and the Rossland background soil (BG) are included below the results for the peat profile. Figure 5-4. Relative concentrations (%) for sequentially extracted fractions in the Cominco profile, including the basal mineral sediment (BSed). Relative concentrations for the Cominco mineral soil (MS) and the Rossland background soil (BG) are included below the results for the peat profile. W l Depth (cm) Depth (cm) W M -\u00C2\u00BB\u00E2\u0080\u00A2 M O Ji i i i 0) w s m w w ffl 10 o ( D \u00C2\u00AB I 0 Q. 0) W CO M i i rv* N) o rv* o cv* 0) o (V-00 o 0s o o o o cn o oo o o o SSI Depth (cm) Depth (cm) 0 3 , I -vi i 00 73 (D CL C 0) 0 0 CQ 0) CO c \"D 3\" d CD CO 0) 5 o' O zr CD_ 0) 0 70 CD a c o cr CD W M i i k W 1 0 R 4- i i I \" I 1 o 0) o 3 0) <-t-CD m X o \u00E2\u0080\u00A2y 0) 3 (Q CD 0) d ; CD Ni O A o 0s 00 o O o 03 0 CO \u00C2\u00B0 D 0) 0-03 w N) (/) N) O \u00C2\u00AE u ro a 0) w m i 00 I >1 ^ r r i 00 W N) \u00E2\u0080\u00A2l W 1 1 N) O A O 0) o oo o 0s o o U 0 a overlying peat. Organic carbon ranges from 31 weight % at the peat surface to 0.5% in the basal mineral sediment, and total sulphur ranges from 0.33 to 0.01 % (Table 5-1). The exchangeable fraction is a significant sink for Ni, Zn, As, Cd and Pb, (Figs. 5-6 and 5-7). Patterns of distribution with profile depth vary between elements: exchangeable Ni is particularly enriched in the 2-3 cm sample, while exchangeable Zn, As and Cd distributions are variable throughout the profile and the relative proportion of exchangeable Pb increases with increasing profile depth. The carbonate fraction is a significant sink for Pb, Zn and Cd (2-25%), and a minor sink for As, Ni and Cu (up to 4%). The relative percentage of element sequestration associated with the carbonate fraction decreases with increasing profile depth for Zn and Cd, but increases with depth for Pb at the expense of the organic chelate fraction. The reducible fraction is a major sink for Ni near the surface (up to 27%), and for Zn, As, Cd and Pb throughout the profile (17-76%o). The organically chelated fraction is a major sink for Pb and As, and a minor sink for Sb. The percentage of As and Pb sequestered in the organic fraction decreases with increasing profile depth. The sulphide fraction is significant for Ni, Cu, Zn, As, Sb, and Pb at the surface and in the basal mineral sediment. The relative percentage of Ni, Cu, Zn, As, Cd and Pb associated with the sulphide fraction decreases with increasing profile depth, to a minimum in the 19-20 cm sample, and then sharply increases in the underlying mineral sediment, similar to the Cominco profile. The absolute concentrations of trace elements in the sulphide fraction are also significantly higher for Ni, Cu, Zn and Pb, Concentration (ppm) - i N) W ^ o o o o o o o o o Concentration (ppm) \u00E2\u0080\u00A2 -k N3 K> cn o cn o cn o o o o o o o o o o o -A-Sb \u00E2\u0080\u0094 Cd -\u00E2\u0080\u00A2-Cu -4-Ni Pb Zn Figure 5-5. Total element concentrations within the Thunder Road profile, including basal sediment (Bsed). c N -Q CL 3 o 73 o (A < A W \u00C2\u00A9 jD 1o jc xi CO Sb -As -Cd Cu -Ni Pb Zn Figure 5-8. Total element concentrations within the Champion Lakes profile. 1?-JE R Z B 4 o -o 1?0|-n ? 80-40-10 8 6 c/>\u00C2\u00A3 4 2 0 S w oo ca XI CO ni a> iB \u00C2\u00A9 2>(0 5 c c ~ (OO \" -5-e -a x to a) HI o an \u00C2\u00A9 0 TJ JO 1c a) .a. -C 3 O CO _ o \"Q co ' c \"c -5 CO CO s O O Q f l i n n Sample Depth (cm) Figure 5-9. Absolute concentrations (in ppm) for sequentially extracted fractions in the Champion Lakes profile, and for a nearby mineral soil (MS). Figure 5-10. Relative concentrations (%) for sequentially extracted fractions in the Champion Lakes profile and a nearby mineral soil (MS). Depth (cm) Depth (cm) --J CD 00 ro i. CD CO CD cn ro ro i 00 CD cln clo ro i X O o CD CD cn cn ! I I i CD \u00E2\u0080\u00A2si O) ^ U M - i _ (D CO (D Ul N) ^ ^ i i i i i i ^ 00 O) Ol W N) - 1 1 / 1 O ^ O O) ffl Ul IV ) o -fv CD N 3 CD CD OO O O CD u ro CD cn NJ i ro cn co to 0 0 ) 0 ) 0 1 0 1 CD -t^ CO CO CO CO cn CD CO (1) UI IJO -P\u00C2\u00BB ^ 00 CD (Jl w M A C/D q o \u00C2\u00A9 O) Oi N3 CD -H* CD o C CD CD OO CD C D C D ON \"-J Sb 40% 60% E o Q. a) Q 100% 0% 20% Cd 40% 60% 80% 100% 2-5 14-15 22-26 35-36 49-50 63-64 79-80 MS -I mwmm& - u wniwwiai i m m - T i a v . - . v rmzFTXxx; ' i - - v//\"\"//'///////////// r WV S/////////. c w i i i i i 0% 20% Pb 40% 60% 80% 100% E o a. a> Q 2-5 22-26 49-50 MS E i h 1 1 i 1 1 mmmmmtm -1 1 vmmmtmtm^ WMwmmsm \----mmmmmmmmmi: Residual 5.5.2.4 Comparison to results of sequential leaching from soil and stream sediment samples Samples of mineral topsoil from the Cominco and Champion Lakes sites and from a background site located near the town of Rossland were sequentially extracted following the procedure used for the peats in order to determine if differences in mode of occurrence exist between mineral and organic soils. The extraction data for the Cominco and background soils is presented in Figures 5-3 and 5-4, and the Champion Lakes data is presented in Figures 5-9 and 5-10. Total concentrations for trace elements in the Cominco site soil were typically lower than those measured in the surface samples from the peat profile, with the exception of Ni and Sb, which were similar. Trace element concentrations in the Rossland soil were much lower than the Cominco site soil, with the exception of Ni, which was higher in the background soil (Fig. 5-3). Organic carbon and sulphur contents are 6.4 weight % C and 0.05 weight % S for the Cominco site and 0.05 weight% C and 0 weight% S for the background soil, respectively. The total concentrations of Cd, As and Sb in the background soil are less than 2 ppm each, and extraction recoveries of these elements do not exceed 1 ppm for any fraction. Concentrations of trace elements in the Champion Lakes soil are similar to those found in the surface peats for Cd, Cu, As, and Sb, higher for Ni, and lower for Pb and Zn. The organic carbon content of the Champion Lakes soil is 13.5%, and the sulphur content is 0.06%. The mode of occurrence of trace elements in the mineral soils differs somewhat from that seen in the peats. Nickel, Cu, Zn, As, Cd and Pb are associated with the sulphide fraction in both the Cominco and the background soil to a greater extent than in the peats. Sulphides are also a significant mode of occurrence for the aforementioned elements in the Champion Lakes soils, and absolute concentrations of trace elements in the sulphide fraction of the soil are equivalent to those in the surface peats. The sulphide component of the background soil is surprising, given that sulphur was not detected by the sulphur analyser. This result may be due to sample heterogeneity, or the inability of the sulphur analyser to decompose the sulphur species present within the soil. Alternatively, this result may indicate that the peroxide extraction is not specific to sulphides. Carbonates are an important sink for Pb, Zn and Cd in the Cominco and Rossland soils, and a minor sink for Pb in the Champion Lakes soil, similar to the peats. Pb and As were measured within the reducible fraction of the Cominco soil at similar percentages to the peat, while the reducible Cd and Zn fractions represent a smaller percentage of the total element concentration than in the peats. The reducible fraction is a major sink for Pb, Zn and Cd in the Champion Lakes soil, and a minor sink for As. The relative importance of the reducible fraction is greater in the Champion Lakes mineral soil than in the peat (e.g. 53% of the Pb in the soil is found in the reducible fraction, versus 6% in the surface peat sample). The reducible fraction is a relatively minor sink in the background soil from Rossland. The background soil contains little organic matter and so has little capacity to sequester metals in the organic fraction. The Cominco site soil has higher organic C, and the organic fraction is a sink for As, Cu and Sb (10-14%). The organic fraction of the Champion Lakes mineral soil retains Pb, As, Sb and Cu (8-11%). The residual fraction is a major contributor to the total Ni, Zn, Sb, Cd and Pb in the background soil from Rossland, while the residual fraction from the Cominco site soil is a major mode of occurrence only for Ni, Zn, and Sb. The Champion Lakes mineral soil residual fraction is the largest sink for Sb, and an important fraction for Ni, Cu, Zn, As, and Pb (11-28%). Surprisingly, the residual fraction of the surface peat is a larger contributor of all the examined trace elements than the residual fraction in the mineral soil, in terms of both relative and absolute concentrations. The reason for this finding is uncertain. In summary, trace elements within both the Cominco soil and the background soil are concentrated in the sulphide and residual fractions, and are not sequestered by the reducible, carbonate exchangeable or organic fraction to the same extent as in the peats. Both of these soils are sandy and contain little organic matter, and so have little capacity to retain trace elements mobilised by weathering from particulates or deposited as ionic species in precipitation. The Champion Lakes mineral soil is an organic-rich topsoil from a forested area, and is capable of retaining mobile species through a variety of mechanisms. 0% -t\u00E2\u0080\u0094\u00E2\u0080\u00A2 Hanna Creek 20% 40% 60% 80% 100% Sb As Cd Cu Pb Zn +-S b b b mmwam _ T - . W ^ K \u00E2\u0080\u0094vs/m 3 W/Zmv-A mmm o% 20% Ryan Creek 40% 60% 80% 100% Topping Creek 20% 40% 60% 80% Blueberry Creek 40% 60% 80% 100% t = j Exchangeable g g Carbonate HH Reducible Organic Chelate Organic/Sulphide Residual Figure 5-11. Relative concentrations (%) for sequentially extracted fractions in selected stream sediments. Stream sediments were sequentially leached following the same procedure as was used for the peats. Sediments from four localities were examined: Upper Trail Creek, located near the Thunder Road site; Lower Ryan Creek, located near a zinc concentrate unloading site, which has been shown to be subject to high trace element inputs from fugitive emissions (Goodarzi et al., 2G03); Upper Blueberry Creek, located north west of the smelter; and Middle Hanna Creek, located between Trail and Blueberry Creeks (Fig. 5-1). The Ryan Creek sample has higher concentrations of sulphide-associated Cd and Zn relative to the other streams, due to the impact of the ore concentrate unloading site (6% Cd, 13% for Zn; Fig. 5-11). However, the relative contribution of other elements in the sulphide fraction is minor at Ryan Creek, and negligible at the other sites. Antimony, As, and Cu are found mainly within the residual fraction at all sites, reflecting the geogenic nature of these elements, or at least their non-bioavailability in stream sediments. Cadmium exists primarily in the exchangeable fraction (>41%). Cadmium, Zn and Pb are also found in the carbonate fraction, particularly in the Hanna, Ryan and Trail Creek sites (9-17% for Pb). Reducible Pb, Zn, Cd and As are important modes of occurrence at all locations. 5.6 Discussion 5.6.1 Controls on Speciation 5.6.1.1 Adsorption The adsorption (ionic bonding) of elements to surfaces is a function of pH, the charge concentration of the adsorbing substrate and the concentration of the charged ionic species (e.g. Elder, 1988). Adsorption behaviour of a given ion to a given surface is strongly influenced by pH, with the relative percentage of adsorbed species versus pH being described by a steep \"adsorption edge\" Langmuir-type isotherm over a short range of pH. The pH at which this isotherm occurs is variable, depending on the properties and concentration of the adsorbed element and the availability of sites for adsorption. It has also been shown that organic substances and oxyhydroxides of Fe and Mn may coat mineral particles, thus altering the absorptive capacity of the minerals (Davis, 1984). The expected adsorption behaviour may also be disrupted by competing reactions in heterogeneous systems (Jacquier et al., 2001). For these reasons, it is difficult to predict the adsorption behaviour of elements in natural systems. Nickel, Cd, Zn, and As were found in the exchangeable fraction in all profiles, while exchangeable Pb and Sb were only measured in selected samples. Exchangeable Cu is not an important fraction in any peat, soil or sediment. Forstner and Haase (1998) point out that the metalloid As, unlike the heavy metals, commonly exists as an uncharged species in natural waters through a range of Eh and pH conditions, and so is not as susceptible to immobilization by sorption. However, As was removed in the exchangeable fraction in most samples, indicating that the As was present either as an adsorbed or water soluble species. Adsorbed elements are held to surfaces via ionic bonding, and are highly susceptible to desorption due to changes in pH or displacement by other charged species. For this reason, the exchangeable fraction can be considered to have a high potential mobility. 5.6.1.2 The Carbonate Fraction Carbonate ligands maybe produced as a result of dissilimilatory sulphate reduction, according to the equation 9CH20 + 4S042\" + 4Fe(OH)3 + 4Me2+ - \u00C2\u00BB 4FeS + 4MeC03 + 15H20 + 5C02 (Berner, 1984; Clark, 1998). Carbonate ligands may also be present in solution as a result of inorganic processes, such as the dissolution of carbonate minerals, and from dissolved atmospheric CO2. Carbonates are an important sink for Pb, Zn and Cd in the peat profiles and soil samples, indicating reprecipitation of mobile ions of these elements. Based on Eh-pH diagrams, the weakly acidic to neutral conditions in the peat favour the formation of PbC03 relative to Cd and Zn carbonates (Brookins, 1988), in agreement with the observations. Gee et al. (2001) determined that PbCC>3 is soluble below a pH of 5, releasing the Pb to solution, suggesting that the carbonate fraction would not act as an effective sink for Pb in more acidic peats. The importance of the carbonate fraction as a sink for Pb, and to a lesser extent, Zn, and Cd, in a variety of environments has been noted by numerous authors. Lead carbonate was noted as a weathering product on the surface of Pb shot from a shooting range (Rooney et al., 1999). Carbonate species were determined to be an important mode of occurrence for Cd, Zn and Pb in soils around a modern Pb-Zn smelter (Verner et al., 1996), and in soils contaminated by mining wastes (Song et al., 1999). Cerussite was determined to be the major mineral association for Pb at historical smelter sites, and an important control on Pb mobility (Maskall et al., 1996; Gee et al., 1997; 2001; Lee and Thornton, 2001). Carbonate-complex formation has been shown to be an important reaction in anaerobic constructed wetland environments (Barton and Karathanasis, 1998) and in anaerobic soils (Charlatchaka and Cambier, 2000). 5.6.1.3 The Reducible Fraction In agreement with the findings of the current study, the reducible Fe/Mn fraction has been shown to be an important sink for trace elements in peats (Bendell-Young, 1999; Bendell-Young et al., 2002), mineral soils (Karczewska, 1996; Verner et al., 1996; Astrom, 1998; Rieuwerts et al., 2000; Lombi et al., 2000; Palumbo et al., 2001; Lee and Thornton, 2001; Davranche et al., 2003) and sediments (Clark et al., 1998; El Bilaili et al., 2002; Lee et al., 2002; Mucci et al., 2003). The reducible fraction is a significant sink for As, Zn, Cd and Pb in the heavily-impacted Cominco and Thunder Road peats, and for As, Zn and Cd in the Champion Lakes peat. The reducible fraction is also an important sink for these elements in mineral soils and stream sediments. The relative significance of the reducible fraction is typically highest in aerobic environments, such as the mineral soils and the Cominco profile. However, it should be noted that the peats were dried prior to treatment, and so some of the operationally-defined reducible fraction may have been attributable to the organic or sulphide fraction within the in situ peat (Forstner, 1987; Kersten and Forstner, 1987), particularly in the case of peats that are predominantly waterlogged, such as Champion Lakes. The precipitation of reducible Fe and Mn compounds is controlled by both biotic and abiotic factors, including pH, Eh, (Brookins, 1988; Kirby et al., 1999; Lee et al., 2002) and the presence of iron-oxidising bacteria (Kirby et al., 1999). Metals are retained by Fe-Mn oxide complexes both by adsorption to negatively charged sites on Fe-Mn oxide surfaces and by isomorphous substitution during precipitation (Herbert, 1996). Palumbo et al. (2001) noted significant enrichment of Pb, Cd, and Ni in Fe-Mn nodules found in alfisolic soils, and found that Cd, Cu, and Ni show a strong affinity for Mn, while Pb shows a strong affinity for Fe. This is in accordance to the findings, of Lee et al. (2002), who found that the adsorption of Pb coincided with the precipitation of Fe-oxide species at pH s4, while Cu, Zn, Ni and Cd were adsorbed at higher pH's, coinciding with the precipitation of Al-oxide and Mn-oxide species. Bendell-Young (1999) found that sorption of Zn was associated with Fe-oxides, rather than Mn oxides, in peats from a range of environments. 5.6.1.4 The Sulphide Fraction The formation of sygenetic sulphides occurs under anaerobic conditions, as a by-product of the dissimilatory metabolism of sulphate-reducing bacteria. These bacteria use organic oxysulphur compounds as terminal electron acceptors in their respiration processes, generating HS~, which reacts with ferrous iron to form framboidal pyrite (Altschulter et al., 1983), according to the following reactions (Tuttle et al., 1969; Altschulter et al., 1983; Southam et al., 2001) CH20 + S042\" H2S + 2HC03\" H2S + Fe2+ FeS + 2H+ FeS + S\u00C2\u00B0 FeS2 Iron (III) is also reduced to Fe (II) by bacteria as a by-product of dissimilatory metabolism. This process is enhanced in the presence of organic matter, which acts as an \"electron shuttle\" between the microbes and the surface of the Fe-bearing mineral (Fredrickson et al., 1998). Iron (III) reduction has been shown to result in the mobilisation of associated trace elements (e.g. Charlatchka and Cambier, 2000; Davranche et al., 2003) in open systems where leaching is extensive and other complexing ligands are not present. However, in a \"semi-closed\" hydrological system such as a peatland, it is likely that trace elements liberated by the reduction of iron oxides will be retained as sulphides or organic complexes, and hence be retained within the peatland. Arsenic associated with Fe complexes in estuarine sediments was found to be rapidly scavenged by newly-formed Fe complexes following changes in redox conditions. This occurred both in the case of anaerobic Fe (II) monosulphides that were rapidly oxidized to form Fe oxyhydroxides (Saulnier and Mucci, 2000), and in the case of aerobic Fe oxides that were rapidly buried, which retained As as Fe-sulphides (Mucci et al., 2003). It is probable that some redox-induced leaching occurs in the peat profiles. The enrichment of reducible fraction-associated elements (Sb, As, Cd, Cu, Pb) in the Cominco profile at 14-15 cm depth may have formed due to leaching from the overlying sediments accompanying the dissolution of Fe-oxides during periods of flooding, with reprecipitation as suphides under the reducing conditions found at depth, followed by conversion to Fe-oxides upon the re-establishment of oxidising conditions. Such concentration \"spikes\" at redox transition zones were noted by Astrom (1998) and Clark etal. (1998). It has long been known that many trace elements found in anaerobic sediments are associated with syngenetic pyrite and other sulphides (e.g. Finkelman, 1980; Casagrande, 1987; Miiller, 2002). In a study of anoxic sediments from a Norwegian fjord, Muller (2002) found rates of trace element coprecipitation with pyrite to be greater than 98% of the total \"reactive concentration\" of Cu, Ni, Zn and Pb. Factors controlling the rate of formation of ferrous sulphides include the availability of sulphide, the availability of ferrous iron, and the availability of organic substrates for dissimilatory microbial respiration. As Fe and S are quite ubiquitous in the environment around the smelter, it is likely that the main control on the formation of pyrite is the presence of reducing conditions, and the main control on the degree of coprecipitation is the extent of competing reactions. Elements may also be precipitated as non-ferrous sulphides (e.g. ZnS). Sulphide-associated Zn, Cd, Pb, Sb, Cu and As make up a significant portion of the total element concentration in soils and the surface peats at the Thunder Road site and in the Cominco mineral soil. The relative contribution of the sulphide fraction to the total element concentration decreases with increasing depth in the Cominco and Thunder Road profiles, particularly for Zn, Pb and Cd. This suggests that some of the sulphide-associated elements in the surface peats and the mineral soils may be derived from sulphide-rich fugitive dust from the smelter, rather than from syngenetic sulphides (Goodarzi et al., 2003; Chapter 4). Sulphides are unlikely to precipitate in aerobic mineral topsoils, and so sulphide precipitation is an improbable mechanism for trapping mobile ions from solution in the mineral soil environment. Syngenetic sulphide formation would be expected to increase with the increasingly reducing conditions found in the deeper peats. However, sygenetic pyrites are often observed within plant cell structures, where reducing micro-environments are created as a result of the decomposition of plant materials (e.g. Altschuler et al., 1983; Cohen et al., 1983; Chague-Goff et al., 1996). This suggests that trace elements may be coprecipitated with sulphides in sediments that are predominantly aerobic. Alternatively, it is possible that not all the organically-associated elements were removed by Na-pyrophosphate in the previous extraction step. Hall et al. (1996a) determined that two 1-hour extraction periods were sufficient to extract the majority of the Na-pyrophosphate extractable metals, although it is possible that some of the organically-associated elements are not extractable by this method. The pattern of increasing sulphide association with depth in the Champion Lakes profile is contrary to the observations in the Cominco and Thunder Road profiles. It is likely that the majority of trace elements associated with sulphides precipitated from solution under the reducing conditions within the peat. The relative contribution of the sulphide fraction is minimal in the peat directly above the basal sediment in both the Cominco and Thunder Road sites. This suggests that the mobile trace elements are sequestered by another mechanism before percolating to greater depth. The increase in relative and absolute concentrations of sulphide-associated elements in the basal mineral sediments suggests either syngenetic coprecipitation of anthropogenic and/or geogenic trace elements from groundwater which preferentially flows through the mineral sediment, or the presence of geogenic sulphide minerals, or possibly a combination of the two factors. 5.6.1.5 Organic complexation The retention of metals by organic matter via complexation with negatively charged functional groups, typically carboxyls, phenols, thiols or amines, as unidentate complexes or bidentate complexes (chelates) is an important factor in the fate of trace elements in the environment. The potential for trace metal complexation is a function of the solution pH, the metal ion in question (Kerndorff and Schnitzer, 1980; Stack et al., 1994; Cohen et al., 1995), the functional group chemistry of the organic matter, and the physical structure of the organic matter (Sohn and Rajski, 1990; Wu and Tanoue, 2001; Leenheer et al., 2003). The fraction of organically associated elements is relatively small when compared to the reducible and carbonate fractions. This may be partially due to the transformation of organically-complexed elements to reducible Fe or Mn species as a result of the oxidation that occurred during sampling and storage (Kersten and Forstner, 1987). The relatively minor contribution of the organic fraction to the total elemental concentration may also reflect a greater tendency for the examined trace elements to form Fe-oxide or carbonate complexes. Nonetheless, the organic fraction is a major sink for Pb in all profiles and is a significant sink for Zn, Cd, Cu and Sb. The Cominco and Champion Lakes soils also contained organically-associated Pb, Sb, As and Cu, while the organic C-poor background soil from Rossland did not. Organic carbon is thus an important parameter to be considered when conducting trace element surveys of mineral soils. 5.6.1.6 The Residual Fraction Trace elements extracted from the residual fraction are believed to be predominantly geogenically derived, and are frequently associated with silicate minerals. The residual fraction also contains all the elements associated with other phases that were incompletely extracted previously (e.g. some crystalline sulphides and Fe-oxides may remain within the sediment). Silicate slags from the smelter may also be resistant to all previous extracting solutions. The residual fraction is the major source of Sb and Ni, and is a significant mode of occurrence for Cu, Zn, Cd and Pb in the Cominco and Thunder Road profiles. The relative contribution of this fraction typically increases with increasing profile depth, indicating a probable partial geogenic source for these elements, or at least increasingly limited mobility for the trace elements in the deeper peats. The relative significance of the residual fraction decreases to zero for all elements other than Zn and Sb with increasing peat depth in the Champion Lakes peat. The relatively high concentrations of Pb, Zn, Sb, and Cd at the surface of the profile suggest deposition from the smelter, although a large proportion of these elements are in the residual fraction, which suggests a geogenic origin. The proposed geogenic origin for the trace elements is supported by the SEM examination of the peat, in which no trace element enriched particulate material from the smelter was observed (Chapter 4), and by the atmospheric deposition monitoring program, which measured little smelter impact at this location (Goodarzi et al., 2003). The increase in residual trace elements at the peat surface may be due to increased input of inorganic particulate matter due to enhanced erosion as a result of anthropogenic activities. The lack of residual-associated elements below 50 cm may be due to the gradual dissolution of detrital minerals within the peat at depth (Bennett et al., 1991), or due to a lack of deposition of detrital materials at the time of peat formation. 5.6.2 The role of source material in determining mode of occurrence There are several potential sources of trace elements to the peats, which influence the mode of occurrence. Heat-treated particulate material is released from the smelter during the course of ore processing (Goodarzi et al., 2003; Chapter 4). These particles are typically oxides, sulphates and silicates enriched in Pb and Zn. Freshly deposited particles from the atmospheric monitoring stations observed by SEM frequently had strong O peaks on the EDX spectra (Goodarzi et al., 2003). A similar SEM investigation of the peat ash materials did not reveal this strong O signal in similar particles, suggesting that these heat-treated materials are subject to weathering and solublisation in the environment, in accordance with the findings of Davranche et al. (2003). These mobile elements are leached from the site of deposition and migrate as soluble species until they become sequestered in the peats, in the exchangeable, carbonate, reducible, organic or sulphide fractions. Carbonates and the reducible fraction are also a major sink for elements within the soils, however, overall trace elements concentrations tend to be higher in the peats, particularly for elements that do not readily form carbonate species (Cu, As). Elements which are not weathered from these silicate particles are likely to be extracted in the residual fraction. A second source of trace elements in the area surrounding the smelter is fugitive dust released from ore feedstock material during transportation and storage. This dust is composed primarily of sulphides and the associated trace elements. Goodarzi et al. (2003) cite fugitive dust from smelter feedstock as the most significant source of trace elements in the area immediately surrounding the smelter, although stack-emitted materials make up a greater relative contribution with increasing distance. The significance of this fugitive material in the peats from the Cominco and Thunder Road sites was noted in Chapter 4 in an SEM-EDX study of peat ash materials. This suggests that a portion of the sulphide fraction from the Cominco and Thunder Road sites is derived from fugitive dust, rather than sulphides precipitated in situ. Secondary sources may also contribute to the trace element concentrations and influence their mode of occurrence. Cadmium at the Thunder Road site is believed to be partially derived from past emissions from the fertiliser plant, which previously produced phosphate fertilisers, although only N-fertilisers have been produced for the past decade (W. Duncan, personal communication). The Cominco site is located in close proximity to a major roadway, and so may be subject to significant input from automobiles (e.g. brake dust, and previously, Pb from gasoline), road dust and salt. There may be additional secondary sources that were not identified (e.g. old mining spoils, undocumented landfills, agricultural chemicals) and so it is difficult to accurately determine the impact that these diffuse sources may have on the concentration and mode of occurrence of the trace elements. A fourth source of trace elements is local geogenic input. The geology of the Trail area is diverse and natural background geochemistry is known to be variable, with areas of high grade sulphide-hosted ores (Beddoe-Stephens and Lambert, 1982; Little, 1982; Sevigny, 1990; Hoy and Andrew, 1989,1991). For this reason, it is not reasonable to assume a single value will represent the geogenic background for the study area. Crystalline sphalerite was observed in the Champion Lakes peat by SEM-EDX, and several geogenic particles were observed to contain Pb and Zn, although these may have been surface coatings, but no minerals associated with high trace elemental concentrations were detected by XRD (Chapter 4). Elements derived from local geogenic sources may be associated with the residual or sulphide fraction, or may be found within any of the other fractions as a result of mobilisation during weathering and subsequent sequestration. 5.7 Conclusions Sequential leaching of peat and soil samples subject to variable input from a Pb-Zn smelter illustrates that mode of occurrence is a function of the geochemical conditions within the peat and the sources from which the trace elements are derived. In the heavily impacted peat profiles, As, Cd, Zn and Pb are typically sequestered as exchangeable species, carbonates, Fe-oxides or organic complexes, indicating that these elements were most likely precipitated within the peat from solution, and may be subject to subsequent mobilisation, while Ni and Sb are commonly found in more stable residual forms. Mineral soils, which are relatively depleted in mobile trace elements compared to the nearby peats, generally contain higher proportions of trace elements associated with the recalcitrant residual and sulphide fractions, due to leaching of more labile species. Peats from a profile subject to less deposition from the smelter contained a greater proportion of residual and sulphide associated elements, due to the higher relative contribution of geogenically-derived materials. 5.8 References Altschuler, Z.S., Schnepfe, M.M., Silber, C.C. and Simon, F.O., 1983. Sulphur diagenesis in everglades peat and origin of pyrite in coal. 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Chapter 6 The organic petrographic characteristics of peats from an area of high trace element input 6.1 Introduction While chemical analyses are critical in evaluating sediment samples from areas subject to anthropogenic environmental impact, microscopic methods which characterise the enclosing sediments can contribute valuable complimentary information. In the case of peat sediments, organic petrographic methods are particularly useful. Organic petrography can be used to quantitatively characterise the phyteral composition of a peat, and to reconstruct a general depositional history of the peat in terms of the redox conditions, microbial populations and the nature of the vegetation. The conditions within the peatland have important implications for the capacity to sequester metals, as metal mobility is a function of numerous interrelated factors such as the redox conditions, the pH, and the potential for metal retention by sorption, complexation, coprecipitation and chelation by various components found within the peat. These environmental parameters are imprinted on the peat in terms of the extent of humification, gelification and oxidation, as indicated by the content of huminitic and inertinitic macerals. This study examines the organic petrographic characteristics of peats from the area surrounding the Teck-Cominco Pb-Zn smelter in Trail, British Columbia, Canada, and is part of a Geological Survey of Canada-Teck Cominco project to determine the trace elemental impact of the smelter on the surrounding area. The capacity for peats to retain selected trace elements (Sb, As, Cd, Cu, Pb, Ni and Zn) relative to the mineral topsoils was discussed in Chapter 2. It was observed that the small shallow peatlands in the region are significant sinks for mobile metal species deposited from the smelter. Both the total concentration and the mode of occurrence of selected trace elements as determined by sequential leaching vary as a function of profile depth (Chapter 5). Thus, characterising the maceral composition of the peat enables discussion of the behaviour of the trace elements as a function of the prevailing conditions within the profile. A reflected light microscopic investigation was conducted to achieve two objectives: 1. To characterise the peat in terms of the nature of the constituents and the degree of diagenesis due to chemical and biochemical humification. Stack et al. (1994) and Cohen et al. (1995) have demonstrated that metal sorption by peats varies both as a function of the individual metal and of the peat characteristics. The extent of humification may have implications for the sorption capacity of the organic fraction for metals. Although there is no single accepted model for the early diagenesis of organic matter, it is generally proposed that as humification proceeds, cellulose is mineralised and the more recalcitrant lignin compounds become increasingly molecularly condensed, leading to a decrease in functional groups available to chelate and sequester metal ions. Due to overprinting by factors such as differing amounts of anthropogenic deposition and variable bedrock geochemistry between the sites, it is not reasonable to expect metal concentrations to be meaningfully correlated with the degree of peat humification on a site-to site basis. However, since the organic fraction, as defined by sequential leaching, has been shown to be an important repository for metals (Chapter 5) the degree of humification is a parameter worthy of further observation. Organic petrographic methods may also be used to construct a history of diagenetic conditions within the peat profile. Characteristics such as the Eh and pH conditions may be inferred from the degree and type of diagenesis. Gelification (loss of ligno-cellulosic cell wall integrity) occurs under anaerobic conditions due to bacterial activity, while humification (mineralisation of organic matter) and fungal degradation of lignin require aerobic conditions, and occur at a much faster rate than gelification. The presence of funginite (fungal remains) may also be used as an indicator of past or present aerobic conditions, as fungi are obligate aerobes. Other inertinite macerals such as semi-fusintite and inertodetrinite may indicate in situ oxidising conditions, or may be allochthonous (e.g. ash material transported by wind from forest fires). 2. To qualitatively characterise the mineral matter within the peat samples. Mineral matter within peats may be of both detrital (e.g. quartz particles) and neoformed origins (e.g. pyrite). Detrital mineral matter may be a source of geogenic trace elements, while neoformed sulphide minerals may sequester aqueous metal species. 6.2 Sampling Locations The Teck-Cominco smelter is located in Trail, British Columbia, situated in the Columbia River Valley within the Columbia Mountains. The smelter has been in operation since 1896, and produces Pb and Zn as its primary products, as well as Cd, In, Ge, Ag, Au, Bi, Cu, As, sulphuric acid and ammonium sulphate fertiliser. The sampling locations are underlain by Jurassic and Cretaceous plutonic rocks emplaced during the Columbian Orogeny (the Nelson Intrusives), and Jurassic metavolcanic and metasedimentary rocks (the Elise Formation). Due to the relatively dry climate, peatlands in the region are few in number, and of limited size and depth. A description of the sampling sites is provided in Table 6-1, and their locations are indicated in Figure 6-1. Photographs of the sampling sites are provided in Figure 6-2. Site Bedrock Geology Vegetation pH and Comments Cominco UTM Zone 11,0446226, 5440375 Trail Pluton (granodiorite, quartz diorite) Typha latifolia (common cattail), Epilobium ciliatum (purple leafed willow herb) Carex urticulata (beaked sedge) Equisetum palustre, and Deschampsia cespitosa (tufted hairgrass) 5.3 (surface) 5.6 (mineral sediment) 5.7 (pore water) -saturated at the time of sampling, although gleying was noted in the uppermost 15 cm-intermittently aerobic. Zones of oxidation were noted around roots. Thunder Road UTM Zone 11,0445145, 5440974 Trail Pluton (granodiorite, quartz diorite) Typha latifolia (common cattail), Pinus sp. (pine) Betula sp. (birch) Epilobium ciliatium Equisetum palustre, and Deschampsia cespitosa (tufted hairgrass) 5.0 (surface) 5.4 (mineral sediment) 5.7 (pore water) -watertable was approximately 10 cm below the surface at the time of sampling Champion Lakes Provincial Park UTM Zone 11,0453623, 5448726 Elise Formation (flow breccia, lava agglomerate, volcanic breccia, tuff, tuffaceous conglomerate, andesite, basalt, augite porphyry, metamorphosed to greenschist facies). Limestone xenoliths and calcite amygdules found within mafic flows. Economic deposits of Pb, Zn Ag, associated with sulphides. Carex sp. Nuphar lutea (cow lily) Assorted grasses 6.5 (surface) 6.5 (15cm depth) 6.4 (pore water) Saturated profile Bombi Summit UTM Zone 11, 0459296, 5454509 Bonnington Pluton (hornblende rich granodiorite, granitic gneiss, amphibolite) Carex Assorted grasses Organic rich-sediment, not peat Possible urban contamination, due to proximity to road Table 6-1. Description of sampling sites, bedrock geology and vegetation. 117\u00C2\u00B046 117\u00C2\u00B034 \"149\u00C2\u00B015* | QUATERNARY \u00E2\u0080\u00A2Unconsolidated sediments; till, sand gravel, silt JU^STC/CRETACEOUS 1 NEUSON INTRUSIONS: \"granodiorite; minor quartz diorite and diorite X ROSSLAND MONZONITE: -ibJdJite-bornblBnde-augite monzonite, mainly medium grained C iELj^E FORMATION: da, massive andesites aiu Lwsdlts, agglomerate, tuff, breccia, laminated siltstone PALEOZOIC [TH.UO|JNT ROBERTS FORMATION: L^jblagksiltstone and argillaceous quartzitB, slate, greywacke, chert pebble conglomerate, lava; Kmestone J J^OWN L GNEISS: libolite and grey biotite gneiss, hcmblende gneiss, mica schist, aplite and Kilometres 1 0 1 i i r Figure 6-1. Geological map of the Trail area, indicating the location of sampling sites. Figure 6-2. Location photographs a. Teck-Cominco smelter b. Cominco sampling site c. Cominco peat profile during sampling d. Thunder Road sampling site e. Champion Lakes sampling site. f. Bombi Summit sampling site. 6.3 Methodology Sites were selected in order to encompass a range of suspected impact from the smelter. Each site was sampled by digging a small pit and removing blocks of peat from the pit wall. The peat was sealed in zip-top freezer bags and was refrigerated within 12 hours of sampling. Whole peat samples were sectioned into 5 cm oriented blocks in order to obtain a representative continuous profile for analysis. The blocks were freeze dried until desiccated. The samples were placed in rubber moulds greased with petroleum jelly, impregnated with resin under a vacuum and allowed to cure overnight. The samples were then removed from the moulds and polished with progressively finer grit paper on a polishing turntable. The final mirror surface was achieved through the use of Al-flour slurry and a silk polishing cloth. The point counts were carried out using an oil immersion objective on a Leitz reflected light microscope, using white light to observe mineral matter and blue light for organic matter. Four hundred counts per block were used to calculate volume percentages for maceral composition. Maceral terminology followed ICCP guidelines (ICCP, 1971; 1997) adapted for peats (e.g. Esterle et al., 1991). Sequential leaching was performed, and is discussed in detail in Chapter 5. The procedure followed is modified from Tessier et al. (1979) and Hall et al. (1996). Elemental concentrations were determined by Instrumental Neutron Activation analysis (INAA) and inductively coupled plasma mass spectrometry (ICP-MS), performed by Becquerel Laboratories in Mississaugua, Canada, and ICP-MS performed at the University of British Columbia (Refer to Chapters 2 and 5 for further details). 6.4 Results and Discussion 6.4.1 Trace Element Concentrations The highest concentrations of Sb, As, Cu, Pb, Ni, and Zn are found in the Cominco profile (Table 6-2). Cadmium concentrations are highest in the Thunder Road profile. Trace element concentrations are considerably lower in the Champion Lakes and Bombi Summit profiles. A complete discussion of total trace element concentrations in the peats and the results of a sequential leaching process is presented in Chapter 5. Sample Depth (cm) Sb ppm As ppm Cd ppm Cu ppm Pb ppm Ni ppm Zn ppm COMINCO 0-1 126 78.5 61.7 196 3550 10.8 5910 1-2 141 97.8 65.2 223 3830 11.6 5600 2-3 128 153 53.8 215 3780 15.4 4230 3-4 142 116 60.3 227 3830 13.2 4730 4-5 121 164 47.1 214 3940 14.8 3570 17-20 85.0 247 60.1 226 5240 12.4 3040 THUNDER ROAD 0-1 34.1 60.0 119 82 1670 9.2 2730 1-2 37.7 64.4 105 103 2070 10.6 2270 2-3 33.0 62.0 139 84 1750 9.4 2900 3-4 37.6 65.4 134 96 1980 11 2590 5-6 32.5 67.5 104 92 1990 10.8 2330 11-14 34.9 59.0 120 96 1940 11 2300 CHAMPION LAKES 0-1 1.2 1.8 2.4 12 77 3 148 1-2 1.6 3.6 3.7 16 101.5 6 194 2-3 5.5 8.3 6.0 14 172 9.2 214 3-4 3.8 6.8 4.4 13 114.5 6 208 4-5 9.0 15.4 6.8 20 246 8.8 268 11-16 15.2 15.8 6.5 24 324 4.4 178 BOMBI SUMMIT 0-1 2.2 2.9 2.1 14 79.5 12.8 130 1-2 3.0 7.8 2.1 15 104 10.2 122 2-3 2.8 22.6 2.1 13 108.5 11.2 116 3-4 5.0 7.8 3.3 18 191 11.4 150 4-5 8.8 9.8 7.9 29 476 10.8 248 6-7.5 2.5 4.1 1.1 8.2 82.1 9.8 85.3 7.5-9 1.3 5.2 0.8 6 35 12.4 76 Table 6-2. Concentrations of trace elements in the peat profiles. (1) CT) O E x a5 -g 2 P fc w 3 C 'E 0 [c X 0 -4\u00E2\u0080\u0094' c 0 \u00E2\u0080\u00A24\u00E2\u0080\u0094' ' c >> \u00E2\u0080\u00A2C Q. O O ._ CL u-h \u00C2\u00B0 O CL _ O (/) Q py Japuniij. jqiuog OOUjlUOQ >n uoidiueqo Figure 6-3. Organic petrographic composition of the peat profiles, expressed as volume % Results of the point count are summarised in Figure 6-3. A cross plot of structured/unstructured huminite macerals versus inertinite macerals (Fig. 6-4) provides an illustration of the extent of humification within each of the samples. 6.4.2 Organic Petrography and Mode of Occurrence 6.4.2.1 Cominco The peat from the Cominco site is sapric, with small (approximately 5 mm) fragments from reeds and rootlets. At 17 cm depth, large woody roots, approximately 1 cm in diameter, are present. At the time of sampling, the water table was very close to the surface, and the peat profile was completely saturated. The pH at this site ranges between 5.3 (surface peat) to 5.6 (mineral sediment), while the pore water had a pH of 5.7. This site is located approximately 0.5 km from the smelter and is known to be subject to heavy impact from the smelter (Goodarzi et al., 2003; Chapter 2). The organic petrographic makeup indicates that the Cominco profile consists of well humified peats (22-33 % textinite, 3-18% texto-ulminite and 5-7% humodetrinite/gelinite). The peat at the surface contains less textinite than the peat at depth, indicating that the peat surface is currently subject to more intense humification than it was in the past, and that the capacity of peatland to accumulate organic matter is decreasing, due to drainage and subsequent oxidation. The most abundant liptinite maceral is cutinite, ranging from 2-7%, with lesser amounts of resinite, liptodetrinite and sporinite. Funginite is prevalent throughout the profile, particularly in the uppermost peat (almost 40 %). The role of metals in inhibiting humification by restricting the growth of microbial populations is somewhat uncertain: Brookes and McGrath, (1984) determined that the application of sewage sludge containing heavy metals resulted in decreased microbial mass and respiration, while Filcheva et al. (1996) found no significant decrease in either parameter. Metals may be toxic to some microbes, but the impact is variable between species and between metals (Ledlin, 2000). Although copper sulphate is used as an agricultural fungicide, and the Cu concentration in the Cominco profile is high (up to 226 ppm), the abundant funginite suggests that fungal growth has not been inhibited, and the well-humified state of the 50 45 40 35 .E 30 \u00E2\u0080\u00A2e 0) Z 25 <3 P H 20 15 10 5 0 Well Humified Well Oxidised Well Humified Unoxidised Well Preserved Unoxidised 10 15 Humification Index Textinite/(Texto-ulminite+Humodetrinite) 20 Cominco \u00E2\u0080\u00A2 4 - 9 cm m 9-15 cm Champion Lake \u00E2\u0080\u00A2 5-9 cm O 9-16 cm 25 Thunder Road ' A 0-5 cm A 5-10 cm \u00C2\u00AE10-15cm Bombi Summit \u00E2\u0080\u00A2 0-5 cm \u00E2\u0080\u00A2 5-10 cm Figure 6-4 . Graph of humification index versus total inertinite content. peat suggests an active community of plant-decomposing microflora. The presence of relatively large amounts of semifusinite and inertodetrinite (4.7-5.8%) indicate that the site is frequently subject to intense oxidising conditions or input of combusted materials from forest fires. The peat from the Cominco site contains elevated concentrations of Sb, As, Cd, Cu, Pb and Zn relative to British Columbia (2002) and Environment Canada (2002) environmental quality standards for soils, including Pb concentrations of up to 5240 ppm and Zn concentrations of up to 6170 ppm. Nickel concentrations are below the listed soil quality standards. Concentrations of Sb and Zn are greatest at the surface and increase with depth, while As, and Pb are most concentrated at the base of the profile, and Cd, Cu and Ni concentrations are consistent throughout (Table 6-2). The oxidising, weakly acidic depositional environment indicated by the organic petrographic makeup is confirmed by the mode of occurrence for the smelter-derived trace elements. Both the carbonate and the reducible fractions are important sinks for Pb, Zn and Cd (Fig. 6-5). The carbonate fraction is a significant sink for Pb (9-20%) and to a lesser extent, Zn (1-7%) and Cd (2-7%). The prevalence of the carbonate fraction in this profile corresponds with the well-humified nature of the peat: highly acidic conditions that prevent the precipitation of carbonates also inhibit humification. The formation of Pb carbonate species may occur within the pH range of the peat (Brookins, 1988), although carbonate complexes for Zn, Cd, Ni and Cu are more stable at higher pH's and are thus less prevalent. The reducible Fe and Mn fraction is the major sink for Pb, Zn, As and Cd (19-72%) throughout the profile depth, and a major sink for Ni, Cu and Sb in selected samples. The organic chelate fraction is retains Pb, Sb, Cu and As (generally less than 20%). The sulphide fraction represents approximately 2-4% of the As, Pb, Zn and Cu, and 7-10% of the Sb and Cu at the surface of the peat. The relative importance of the sulphide fraction decreases with increasing depth until the basal mineral sediment Figure 6-5. Relative concentrations (%) for sequentially extracted fractions in the Cominco profile, including basal mineral sediment (Bsed). CD Ca) N ) C/> h O | O \u00C2\u00A3 1 0 Ca) N ) 1 Q 0 ) Ca) \u00E2\u0080\u00A2 I 71 (D w d c Q) o 0 CQ Q) 2 Si U) c T3 :x CL (D CO 0) D O O IT (D r+ (D O 0 s N) O ox ^ O 0 s \"0 o) 0\" 0 s CO o ox O O x\u00C2\u00B0 0 s o co -i cr o D Q) (D m X o D\" \u00C2\u00A3D 3 (Q (D 0) g; (D CD Ca) N ) - A ( / ) K ) O ^ o o \u00C2\u00AE i) N) ' \u00E2\u0080\u00A2M C O IV) n ^ iv \u00E2\u0080\u0094 \u00E2\u0080\u0094x i i i CD 0) l\) J ro o a 0) u s j co u _ __ I I I I i P is reached. This suggests that the oxidising conditions within the peat do not favour the formation of sulphides. 6.4.2.2 Thunder Road Profile This site is located approximately 1.5 km from the smelter and is subject to significant trace element deposition from the smelter, although to a lesser extent than the Cominco site, due to the larger intervening radial distance and partial topographic sheltering (Goodarzi et al., 2003, Chapter 2). The site is also subject to input from a fertiliser factory, which currently produces N-fertiliser, but previously produced phosphate and potassium fertilisers as well (W. Duncan, personal communication). Macroscopically, the Thunder Road peat is uniform in appearance throughout the profile. Fine rootlets ( \u00E2\u0080\u00A2 \u00E2\u0080\u00A2 i CD -t^ CO 0 1 K> O OJ Sb 0% 20% 40% 60% 80% 100% 0-1 _ 2-3 1 3-4 CL 0) \u00E2\u0080\u00A2U E o 5-6 14-15 19-20 BSed 0-1 2-3 3-4 \u00E2\u0080\u00A25. 5-6 0) \"\u00C2\u00B014-15 19-20 BSed -J 1 1 1 1 I K m 1 ife1-mam mm* i -I I I mmm WMBM 1 1 \ M M wMmfflwmmmm j i \u00E2\u0080\u0094 I \ m m m AViTAWA' 1 WMM&MW^^ -] mmmw i i i i i i i Pb 20% 40% 60% 80% 100% mm Cd 0% 20% 40% 60% 80% 100% 0-1 2-3 3-4 5-6 14-15 19-20 BSed m. m ^ ^ Exchangeable Carbonate Reducible Organic Chela te Organic/Sulphide Residual m The relative percentage of element sequestration associated with the carbonate fraction decreases with increasing profile depth for Zn and Cd, but increases with increasing depth for Pb at the expense of the organic chelate fraction. The reducible fraction is a major sink for Ni near the surface (up to 27%), and for Zn, As, Cd and Pb throughout the profile (17-76%). The organically chelated fraction is a major sink for Pb and As, and a minor sink for Sb. The percentage of As and Pb sequestered in the organic fraction decreases with increasing profile depth. The sulphide fraction is significant for Ni, Cu, Zn, As, Sb, and Pb at the surface, but decreases with increasing profile depth. 6.4.2.3 Champion Lakes Profile This site is located in a provincial park, approximately 13.5 km from the smelter. The site is somewhat sheltered from deposition from the smelter due to the intervening mountainous topography, and the fact that the prevailing winds are generally from the northwest (Goodarzi et al., 2003). Peat was sampled from a marsh surrounding First Lake. The peat is fibric at the surface (the top 3 cm), and is yellowish-brown in colour. It gradually grades from fibric to dark brown hemic peat (approximately 7 cm) to black sapric peat (approximately 12 cm), with intact rootlets, and partially humified reeds set in an amorphous matrix. The peat pH was 6.4 at the surface and at depth, while the pore water had a pH of 6.5. The Champion Lakes site peat displays a humification pattern typical of an active peat-forming environment, in that the surficial peat is predominantly minimally-altered textinite-rich peat (55% textinite, 6% texto-ulminite, 2% humodetrinite), while the peat at depth is more gelified (37% textinite, 17% texto-ulminite, 4% humodetrinite). This indicates that the peat below 9 cm is waterlogged, permitting bacterial gelification. The presence of funginite and other inertinite (12-16%) is evidence of intermittent aerobic conditions within the profile, likely due to fluctuations in the lake water levels. The near-neutral pH conditions illustrate the moderating influence of the lake water, which acts to dilute the impact of organic acids generated during humification. Total trace elemental concentrations are much lower in the Champion Lakes profile than at the Cominco and Thunder Road sites. Concentrations of trace elements generally increase with depth (Table 6-2). A minor carbonate and organic chelate association is noted for Zn and Pb at the profile surface (2-9%; Fig. 6-7). The reducible fraction is a sink for Zn, As and Cd at the peat surface (16-21%) and for Zn throughout the profile depth (up to 40%). Sulphides are relatively more important in this profile than for the Cominco and Thunder Road profiles, although overall concentrations are much lower. Sulphur concentrations are higher in the Champion Lakes peat than in the Cominco or Thunder Road peats and thus there is a greater pool of sulphur for the trace elements to react with. The major proportions of Ni, Cu, and As, Sb and Pb at depth are found within the sulphide fraction. 6.4.2.4.Bombi Summit Profile The Bombi Summit organic deposit consists of 7 cm of peat overlying sandy sediment, located approximately 16 km from the smelter. There is a thin (<1 cm) layer of fibrous peat at the surface, while the underlying material is a dark brown to black amorphous matrix with fine rootlets and reed fragments in variable states of decomposition, and coarse sand grains. Large wood fragments (approximately 3.5 cm diameter) are also present throughout the profile. The Bombi Summit peat is moderately humified at the surface (45% textinite), but highly detrital and oxidised in the 5-10 cm sample (6% humodetrinite, 26% liptodetrinite, 19% funginite, 8% other inertinite). The high funginite content (25-28%) indicates that oxidising conditions prevail at this site. Antimony, Cd, Cu, Pb, Zn in the Bombi Summit profile increase in concentration from the surface to a maximum in the 4-5 cm sample, and then decrease to a minimum in the 7.5-9 cm sample. Arsenic is most concentrated in the 2-3 cm sample and Ni concentrations are consistent throughout the profile (Table 6-2). Trace elements are associated primarily with the reducible, sulphide and residual phases (M. Hawke, unpublished data). Ni 40% 60% Cu 60% 100% Zn As _ 0% 20% 40% 60% 80% 100% 0% 20% 40% 60% 80% 100% \u00C2\u00AB 2-5 m m m - ^ i - \u00E2\u0080\u0094 \u00E2\u0080\u0094 n 2-5 1 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00C2\u00A3 1 , | ^14-15 14-15 w/m T3 Sb 40% 60% Cd 40% 60% 80% 100% CL d) \u00E2\u0080\u00A2o 0% 2-5] 14-15 fe 20% i M W W Pb 40% 60% + \u00E2\u0080\u00A2 ! 80% 100% Exchangeable Carbonate j | j Reducible Organic Chelate ^ Organic/Sulphide I Residual Figure 6-7. Relative concentrations (%) for sequentially extracted fractions in the Champion Lakes profile. 6.4.3 Inorganic Matter Micrographs (Fig. 6-8) illustrate some examples of the types of mineral matter observed in the Cominco profile. Of particular interest is the occurrence of permineralised diatoms, pollen grains and plant tissues (Fig. 6-8 d and e), which act as nuclei for precipitation reactions. Finely dispersed sulphide minerals (Fig. 6-8a) are common in all profiles, but are typical epigenetic minerals found in peatlands, and as such cannot be used to infer anthropogenic impact. Examples of high temperature carbonaceous neoformed particulate material (fly ash) occur in several samples (Fig. 6-8b and c). Coal is used to fire the slag furnace, and coke is used as a flux in Pb production, and so the smelter is the most likely source of this material. The peat is also rich in detrital minerals such as quartz (Fig. 6-8f). Figure 6-9 illustrates examples of mineral matter from the Champion Lakes peat, which are similar to the Cominco peats, including permineralised plant materials, fly ash from the smelter and sulphide minerals such as pyrite. Other than the fly ash, no smelter-derived particulate material was observed using light microscopy, although an SEM-EDX study of peat ash material (Chapter 4) identified Pb and Zn containing particles, originating both from the smelter stack and from fugitive feedstock dust, based on the particle morphology. These particles were typically less than 2 pm in diameter, and it is likely that their defining characteristics (rounded or \"fluffy\" morphology) would not be recognisable at the level of magnification used for the point count. Since the particles emitted from the smelter had varying chemical compositions, as determined by EDX (Fe, S, and Si associations), their optical properties under reflected white light may also be variable. 6.4.4 Organic Sequestration of Metals-the role of peat type and humification Trace element fractionation and mobilization is subject to a number of controls, including Eh and pH (e.g. Forstner, 1987). Since redox and pH conditions may fluctuate within peatlands due to both day-to-day and seasonal climatic variation, the concentration and mode of occurrence of the trace elements are likely in a state of flux (e.g. Van Den Berg et al., 1999). Eh-pH diagrams, such as those presented in Brookins (1988), are helpful in determining potential speciation, but are not entirely A m Figure 6-8. Examples of mineral matter found within the Cominco profile. A. Sulphide mineral, probably pyrite B. and C. highly reflecting carbonaceous material (fly ash) produced from the combustion of coal in the smelter operation. D. diatom permineralised with sulphides. E. pollen grain permineralised with sulphides F. oxidised framboidal pyrite and quartz grain. c Figure 6-9. Examples of mineral matter found within the Champion Lakes profile. A. woody material permineralised by sulphides. B. fly ash particle. C. particle of sulphide mineral, probably sphalerite. applicable to situations where mode of occurrence may be influenced by reactions with organic matter or microbial activity. Co-precipitation of trace elements with Fe and Mn oxides is an important mode of sequestration within the aerobic sediments, notably the upper portions of the Cominco and Thunder Road profiles and the Bombi Summit profile. Neo-formed sulphides, similar to the examples illustrated in Figures 6-8 and 6-9, are important trace element sinks in the anaerobic portions of the profiles, such as the Thunder Road and Champion Lakes peats. The role of the microbial community in trace element behaviour is frequently overlooked. In all profiles, there is evidence of an active microbial community, as indicated by the direct evidence of funginite, and the indirect evidence of humified and gelified plant tissues. Microflora have the potential to accumulate significant amounts of trace metals through a variety of mechanisms, including ionic and covalent adsorption to the cell surface, passive and active uptake, and complexation within extracellular polymers such as capsid layers or slime (Ledin, 2000). Amine groups found within humic substances are also attributed in part to microbial and algal sources (e.g. Hatcher and Spiker, 1988). While the population of the microbial community was not determined in this organic petrography study, it is recognised that some of the organic substances responsible for the retention of trace elements in the peat are likely derived from microflora. Rates of peat growth and humification will also affect the concentration of non-mobile atmospherically-deposited elements, as slowly-accumulating peat will be exposed to the atmosphere for longer periods of time (Kempter et al., 1997). The well humified peat at the Cominco site likely accumulates at a slower rate than the well preserved peat in the Thunder Road profile due to higher net rates of organic matter mineralisation, which may partially account for the higher concentrations of trace elements found within the Cominco peat. Dating of the peat deposits would provide information regarding the age of the peats and the accumulation rates, however, this is beyond the scope of the current project. However, the higher rates of trace elemental deposition at the Cominco site relative to the Thunder Road site (Goodarzi et al., 2003) are the most significant reason for the higher concentrations found in the Cominco peat. The ability of organic matter to sequester metals has long been recognised. Metals are held by the organic matter via both adsorption (outer sphere complexes, i.e., exchangeable fraction) and by complexation by organic acid functional groups (inner sphere complexes, i.e., the organic fraction as defined by sequential leaching). Reactions with organic substances may serve both to retain and to mobilise metals, depending upon whether the organic complex is soluble or insoluble. Studies which have noted that the fine fraction of peats typically have greater metal retention capacity than more fibrous peats have tentatively attributed this finding to the greater surface area available for exchangeable ions (Cohen et al., 1995). However, the contribution of the exchangeable fraction may consist of only a small percentage to the total metal concentration, particularly for Sb and Cu (Chapter 5). A more significant mechanism for the retention of metals by organic matter is complexation with negatively charged functional groups, typically carboxyls, phenols, thiols or amines as unidentate complexes or bidentate complexes (chelates). Numerous studies have examined the nature of metal-organic interactions, and have demonstrated that the potential for metal complexation is a function of solution pH, the metal ions in solution, the functional group chemistry of the organic matter, and the physical structure of the organic matter. Kerndorff and Schnitzer (1980) illustrated that metal ions compete for complexation sites, and the order of sorption from solution at a pH of 5.8 was as follows: Hg=Fe=Pb=Al=Cr=Cu>Cd-Zn>Co>Mn. Organic coatings on alumina particles and dissolved organic complexes were shown to enhance adsorption of Cu (Davis, 1984). Amine groups combined with carboxyl groups are thought to be more efficient chelators of metals than carboxyl groups alone (Sohn and Rajski, 1990; Wu and Tanoue, 2001). The structure of humic substances is also cited as an important parameter in controlling the potential for complexation, i.e. structurally complex molecules with abundant negatively charged ligands are more capable of forming bidentate complexes (Wu and Tanoue, 2001; Leenheer et al., 2003). With increasing humification, quinone groups with free radicals are thought to take on a more important role in sequestering metals (Jerzykiewicz et al., 2002), although these complexes are less stable than chelates. As humification proceeds in the early stages of peatification, oxidation of lignin side chains results in an increase in carboxylic acid groups, thereby increasing the potential for metal retention. These side chains are increasingly lost as humification continues to more advanced stages of diagenesis. The peats examined in this study were derived from a variety of vascular plants with rooting systems that penetrate to varying depths, as was observed in the macroscopic observations and by the organic petrographic study. Under these circumstances, fresh materials are constantly input throughout the profile to the maximum depth of rooting, and so the availability of potential complexing organic ligands is unlikely to be a limiting factor. It is difficult to accurately model the organic complexation of metals in an active peat environment, as each organic substance has a different equilibrium constant for each metal (see, for example, Prapaipong et al. (1999) for a summary of thermodynamic properties of metal-dicarboxylate ligand complexes) and the organic composition of the peat is constantly changing. However, it would be worthwhile to characterise the functional group chemistry of peat materials from different vegetation types at different stages of humification, in order to assess their effectiveness as environmental remediation sorbants for metals. 6.5 Conclusions Microscopic investigations of contaminated sediments aid in characterising both the contaminants and the enclosing sediments. An assessment of the organic petrographic characteristics of the peat is a valuable tool in determining the depositional history of the peatland and thus, past and present environmental conditions within the sediment. The environmental conditions within the profile determine the mode of occurrence and thus the potential for remobilisation, should the prevailing conditions change. Well humified peats indicative of near-neutral pH and oxidising conditions are conducive to the formation of reducible Fe-oxide complexes, which may be subject to remobilisation and leaching under reducing conditions. Carbonate complexes are likely to be rapidly solubilised, should the pH decrease. Predominantly reducing conditions are indicated by gelified textinite macerals. Elements precipitated as sulphides under prevailing reducing conditions may be mobilised under oxidising conditions. Light microscopy also allows one to observe neoformed precipitated mineral matter and particulate matter from external sources. 6.6 References British Columbia. Ministry of Water, Land and Air Protection, 2002. Waste Management Act: Contaminated Sites Regulation. Available: http://www.qp.gov.bc.ca/statreg/regAVAVasteMgmtAVasteMgmt375_96/375_96.htm Brookes, P.C. and McGrath S.P., 1984. Effects of metal toxicity on the size of the microbial biomass. Journal of Soil Science, 35, 341-346. Canada. Environment Canada, 2002. Canadian Soil Quality Guidelines. Available: http://www.ccme.ca/assets/pdf/el_06.pdf Cohen, A.D., Stack, E.M., Eltayeb, S. and Durig, J.R., 1995. Applications of peat-based sorbents for removal of metals from water. Extended abstract, I&EC Special Symposium, American Chemical Society, September, 1995. 4p. Davis, J.A., 1984. Complexation of trace metals by adsorbed natural organic matter. Geochimica et Cosmochimica Acta, 48: 679-691. Esterle, J.S. and Ferm, J.C., 1994. Spatial variability in modern tropical peat deposits from Sarawak, Malaysia and Sumatra, Indonesia: analogues for coal. International Journal of Coal Geology, 26: 1-41. Forstner, U., 1987. Metal speciation in solid wastes\u00E2\u0080\u0094Factors affecting mobility. In: Speciation of Metals in Water, Sediment and Soil Systems, L. Landner, ed. Lecture Notes in Earth Sciences, Springer Verlag, pp 13-42. Filcheva, E., Cheshire, M.V., Campbell, C.D. and McPhail, D.B., 1996. Effect of heavy metal contamination on the rate of decomposition of sewage sludge and microbial activity. Applied Geochemistry, 11: 331-333. Goodarzi, F., Sanei, H., and Duncan, W.F., 2003. Deposition of trace elements in the Trail region, British Columbia; an assessment of the environmental effect of a base metal smelter on land. Geological Survey of Canada Bulletin 573, 50 pp. Goodarzi, F., Reyes, J., and Sanei, H., 2002. Concentrations of elements in the stream sediments in Trail, BC and the surrounding area and the natural background concentration. Unpublished report. Hall, G.E.M., Vaive, J.E., and MacLaurin, A.I., 1996. Analytical aspects of the application of sodium pyrophosphate reagent in the specific extraction of the labile organic compounds of humus and soils. Journal of Geochemical Exploration, 56: 23-36. International Commission of Coal Petrology, 1971. International Handbook of Coal Petrography. Centre National de la Recherche Scientifique (reprinted 1985, the University of Newcastle-upon-Tyne). International Commission of Coal Petrology, 1997. Inertinite Classification-ICCP System 1997. International committee for Coal and Organic Petrology. Wellington, New Zealand, 1997. Jerzykiewicz, M., Jezierski, A., Czechowski, F., and Drozd, J. 2002. Influence of metal ions binding on free radical concentration in humic acids. A quantitative electron paramagnetic resonance study. Organic Geochemistry, 33: 265-268. Kempter, H., Gorres, M. and Frenzel, B., 1997. Ti and Pb concentrations in rainwater fed bogs in Europe as indicators of past anthropogenic activities. Water, Air and Soil Pollution, 100: 367-377. Kerndorff, H. and Schnitzer, M., 1980. Sorption of metals on humic acid. Geochimica et Cosmochimica Acta, 44: 1701-1708. Leenheer, J.A., Wershaw, R.L., Brown, G.K. and Reddy, M.M., 2003. Characterization and diagenesis of strong-acid carboxyl groups in humic substances. Applied Geochemistry, 18: 471-482. Little, H.W., 1960. Nelson.Map-Area, West Half, British Columbia (82 FW1/2). Geological Survey of Canada Memoir 308. 205pp. Little, H.W., 1982. Geology of the Rossland-Trail Map-Area, British Columbia. Geological Survey of Canada Paper 79-26, 38pp. Prapaipong, P., Shock, E.L. and Koretsky, C.M., 1999. Metal-organic complexes in geochemical processes: Temperature dependence of the standard thermodynamic properties of aqueous complexes between metal cations and dicarboxylate ligands. Geochimica et Cosmochimica Acta, 63: 2547-2577. Sevigny, J.H., 1990. Geochemistry of the Jurassic Nelson plutonic suite, southeastern British Columbia. In: Project Lithoprobe; southern Canadian Cordillera transect workshop. Lithoprobe Report 11, pp. 41-52. Sohn, M. and Rajski, S., 1990. The adsorption of Cd (II) from seawater by humic acids of various sources of origin. Organic Geochemistry, 15:439-447. Stevenson, F.J., 1994. Humus Chemistry: Genesis, Composition, Reactions. John Wiley and Sons, New York. 496 p. Tessier, A., Campbell, P.G.C. and Bisson, M., 1979. Sequential extraction procedure for the speciation of particulate trace metals. Analytical Chemistry, 51: 844-851. Van den Berg, G. A., Loch, J.P.G., Van der Heijdt, L.M. and Zwolsman, J.J.G., 1999. Mobilisation of heavy metals in contaminated sediment in the River Meuse, The Netherlands. Water, Air and Soil Pollution, 116: 567-586. Wu, F. and Tanoue, E., 2001. Geochemical characterization of organic ligands for copper (II) in different molecular size fractions in Lake Biwa, Japan. Organic Geochemistry, 32: 11-20. Wiist, R.A.J., Hawke, M.I. and Bustin, R.M., 2001. Comparing maceral ratios from tropical peatlands with assumptions from coal studies: do classic coal petrographic interpretation methods have to be discarded? International Journal of Coal Geology, 48: 115-132. Chapter 7 Conclusions 7.1 Key findings resulting from this research The overall objective of the research was to investigate the role of peat deposits in the partitioning of deposited trace elements in the region surrounding a Pb-Zn smelter. The researcher was pursued through a series investigations, some of which were more successful than others. The principal conclusions and recommendations for further research are summarised below. 7.1.1 Trace element concentrations in organic deposits in the area surrounding a base metal smelter Trace elements deposited in the region immediately surrounding the smelter were shown to be highly subject to weathering and mobilisation in the environment, as indicated by concentration differentials noted between peats/organic soils and nearby mineral soils. The preferential sequestration of the mobile trace elements in peats is due to the capacity of organic matter to sequester ionic species, the enhanced potential for precipitation of trace elements under reducing conditions, and possibly to the net inflow of groundwater to peatlands. The finding that the deposited trace elements are subject to mobilisation following deposition indicates that the trace elements should be considered to be potentially bioavailable, which has implications for both remediation (i.e. phytoremediation methods may be effective for removing trace elements from soils) and for environmental policy (i.e. guidelines based on an awareness of the potential for the trace elements to enter the food chain via locally grown produce or through the grazing of livestock on contaminated soils). The concurrent examination of trace element concentration data from peats and mineral soils and the depositional rate data obtained from the moss monitoring program made it possible to identify locations subject to impact from secondary sources (Cd from the fertiliser plant at Thunder Road) and geogenic input (Cu at Champion Lakes). These findings underline the importance of using several types of sampling media when conducting environmental impact studies. 7.1.2 Geochemical finger-printing, using element ratios and REE signatures It was found that the use of conservative element ratios is generally ineffective in the case of this study, both as a means of subtracting the background geochemical input from the peatlands, and as a method for calculating a meaningful \"enrichment factor\" to express the extent of trace element contamination relative to a benchmark factor. It was found that the conservative elements do not necessarily represent a stable geochemical baseline to which it is possible to normalise trace element concentrations. Indeed it was found that the concentrations of the two conservative elements used in this study (Ti and Zr) fluctuated with respect to each other, and relative to the ash content, indicating that so-called conservative elemental concentrations do not actually represent a reasonable proxy for geogenic input. Furthermore, the calculated enrichment factors varied widely, depending on the choice of the media used for the benchmark, and on the conservative element used, rendering their significance as environmental indicators questionable. These findings indicate that although conservative element ratios have been shown to be effective indicators of anthropogenic input in remote ombrotrophic peatlands, in the case of this study they are ineffective. Rare earth element signatures were also found to be relatively ineffective tools for indicating the extent of smelter impact on the surrounding environment. Chondrite normalised REE signatures from smelter feedstocks and wastes were relatively flat, while the REE signatures from peats were highly LREE enriched, similar to soils and stream sediments sampled in the region. This finding indicates that the peat REE signature is most influenced by local geochemistry, and is not extensively impacted by the smelter. REE signatures from moss monitoring media, however, were more characteristic of the smelter materials. 7.1.3 SEM-EDX study of peat ash Scanning electron microscopy was found to be a useful method to identify the source of particulate matter found within the peat ash from the sampling sites. Stack emitted particles, identifiable by a rounded morphology due to rapid cooling, were commonly found in the peats sampled in close proximity to the smelter. Energy dispersive X-ray spectroscopy indicates that these particles contain Zn and Pb, commonly in association with Si, Fe and S. Precipitates containing Zn and Pb in association with Fe were also detected in the samples from the area immediately surrounding the smelter. Angular particles, particularly Zn in association with S, are indicative of either fugitive dust particles or geogenic materials. 7.1.4 Sequential extraction Peats and soils from the region surrounding the smelter were subjected to a sequential extraction technique to determine the mode of occurrence as a function of source and deposition environmental conditions. Trace elements from sites which are known to be heavily impacted by the smelter are typically found to have a mode of occurrence indicative of solubilisation and subsequent reprecipitation or sequestration (i.e. exchangeable, carbonate, reducible Fe/Mn, organic chelate). This finding supports the conclusion from Chapter 2 that trace elements that are emitted from the smelter are subject to extensive mobilisation within the environment following deposition. The predominant modes of occurrence found at the less impacted sites were indicative of geogenic origins (i.e. the residual and, to some extent, the sulphide fractions). The relative distribution of trace element concentrations in each fraction was found to be a function of the redox conditions within the peatland, and the trace element source, and was found to vary between individual elements. 7.1.5 Organic petrography An organic petrographic investigation of the peats indicates that each site is subject to early diagenesis to varying degrees, and that the predominant early diagenetic processes differ from site to site. The Cominco site contained a relatively low volume of textinite, and had abundant inertinite macerals, particularly funginite. This organic petrographic makeup is indicative of a peatland subject to oxidising conditions, supported by field observations and the high relative significance of the Fe-oxide fraction, as determined by sequential extraction. The Thunder Road site, on the other hand, had a higher relative proportion of textinite, with low volumes of inertinite macerals, indicative of a peatland with predominantly reducing conditions. Correspondingly, the sequential leaching results from this site indicated a lower relative percentage of trace elements associated with Fe-oxides, with a correspondingly higher proportion of organically-chelated elements. The organic petrographic composition of the Champion Lakes peat indicates a peatland with moderate preservation potential, but as a significant proportion of the trace elements at this location are within the residual phase, the redox characteristics of the peat have less impact on mode of occurrence. 7.2 Suggestions for Future Research Numerous questions were raised during the course of this project that could be addressed in future research. It would be worthwhile to pursue the following topics further: 1. The peats sampled in this study were from small, shallow, minerotrophic peatlands in an area of complex bedrock geology. A study of ombrotrophic peatlands, subject only to atmospheric input (except at the peatland margins) from an area of high trace elemental impact would provide an opportunity to better discriminate between geogenic and anthropogenic trace elements within the peatland. Detailed transects of a larger ombrotrophic peatland would be useful in determining the extent to which trace elements are mobilised from surrounding mineral soils and sequestered within the peat subject to groundwater influence, while the ombrotrophic portion of the peatland could potentially provide a chronostratigraphic record of trace element deposition. 2. Sampling and monitoring programs employing similar methodologies could be conducted at other smelters in order to determine the extent to which the sandy, undeveloped nature of the mineral soils in the Trail region influences the potential for trace element mobility. Soils with higher clay and organic matter contents could potentially retain trace elements more effectively than the soils surrounding the Trail smelter. 3. The peat was sampled in the field and subsampled in the lab in such a way that oxidation occurred, which most likely resulted in subsequent changes to the mode of trace element occurrence. As a result, the results from the sequential extraction study may not be truly representative of conditions within the in situ peat. While this problem was judged not to be critical in this case, a sampling and analytical program designed to address this problem would be helpful in determining the true nature of the in situ peat geochemistry. Such a program would involve the immediate storage of all samples in an inert gas, and performing all lab work within a glove box under an inert atmosphere. 4. An investigation of pore water chemistry would provide further insight into the processes occuring within the peatlands. APPENDIX A Comparing maceral ratios from tropical peatlands with assumptions from coal studies. Do classic coal petrographic interpretation methods have to be discarded?1 1. A version of this chapter has been published. Wttst, R.A.J., Hawke, M.I., and Bustin, R.M. (2001) Comparing maceral ratios from tropical peatlands with assumptions from coal studies. Do classic coal petrographic interpretation methods have to be discarded? International Journal of Coal Geology, 48: 115-132. A.A.I Introduction A.A.1.1 Maceral Ratio Indexes Depositional environments play a major role in determining the composition and preservation of peat and coals. The geology, climate, vegetation, and the hydrological regime, (e.g. level and flow of groundwater) of the peat deposits influence the distribution and quality of coal. Coal maceral compositions, determined through petrographic analyses, are used to determine the paleoenvironment and contribute to the understanding of composition, compaction and degree of preservation of plant material. Macerals are frequently considered to be plant- and/or environment-specific, and so the assessment of vegetation type, occurrences of droughts and fires, and intensity of humification and microbial activity is possible by studying coal macerals (e.g. Diessel,1982; Styan and Bustin, 1983; Goodarzi and Hill, 1989; Lamberson et al., 1991; Markic and Sachsenhofer, 1997), and many others). Organic petrographic studies have also been utilised to interpret the degree of preservation of peat deposits, and to examine the spatial distribution of inorganic material (e.g. pyrite, clays, quartz, diatoms) as a function of environment. Hence, paleoecological interpretations, such as main floral composition, can be inferred based on petrographic studies of peat deposits (Cohen and Spackman, 1972; Styan and Bustin, 1983; Cohen et al., 1987; Grady et al., 1993; Hawke et al., 1996; Shearer and Clarkson, 1998; Hawke et al., 1999). Ratios of selected \"diagnostic\" macerals, such as the gelification index (GI) or the tissue preservation index (TPI) of Diessel (1992) have been used in coals as indicators of paleo-peat preservational environment. The use of maceral ratios was proposed as a technique to illustrate the interrelationship of two parameters (such as humification versus gelification). The TPI is a ratio of macerals that have undergone little humification (in the case of this study, textinite, texto-ulminite, and semi-fusinte are used) versus macerals which are indicative of advanced humification (humodetrinite). The GI is a ratio of gelified macerals (texto-ulminite, eu-ulminite, macrinite) versus ungelified macerals (textinite). Cross plots of TPI and GI are then subdivided into interpreted \"peat environments of deposition\", based on the supposed characteristics of peats from specific environments. This approach was pioneered for paleoenvironmental interpretations of Permian coals by Diessel, (1986) and has since been used and abused extensively (e.g. Calder et al., 1991; Kalkreuth et al., 1991; Lamberson et al, 1991; Markic and Sachsenhofer, 1997; Vessey and Bustin, 2000). Modified maceral indexes, such as the groundwater index (GWI) or the vegetation index were also applied to non-Permian coals (Calder et al., 1991). The GWI is the ratio of strongly gelified to weakly gelified tissues and includes the amount of mineral matter as an indicator of flooding activity. The VI contrasts macerals of forest affinity with those of herbaceous and marginal aquatic affinity. Although coal maceral indexes have been \u00E2\u0080\u00A2 used extensively, it has been shown that temperate peats from known depositional environments are not readily classified by maceral ratios (Hawke et al., 1999) and that plant composition is probably a more important factor in governing preservation than has previously been thought (Shearer and Moore, 1994). Moreover, no correlation between peat type and depositional environment, climate or tectonic setting occurred in four bogs from New Zealand (Shearer and Moore, 2003). Maceral ratios have also been shown to give incorrect interpretations of Tertiary coals (Collinson and Scott, 1987; Crosdale, 1993). The purpose of this study is to examine the distribution of organic constituents in polished blocks of modern peat deposits from tropical Malaysia, and to determine whether the method of petrographic analysis of peat (as used in coal studies) can be utilised in reconstruction of past environments. In order to examine the potential usefulness of representing maceral ratio indices of modern peat deposits, three different cross plots of maceral contents and maceral ratios were constructed. This organic petrographic study is part of a larger project, examining the peats from Tasek Bera both in the context of biologically and ecologically dynamic sediments, and in the context of coal precursors (Wtist and Bustin, 1999; Wust and Bustin, 2001). A.A.1.2 Organic composition of tropical peats Climate, depositional environment, mire type, and vegetation type dictate peat composition. Tropical lowland peat deposits are often dominated by trees and shrubs (e.g. Polak, 1933; Merton, 1962; Polak, 1975; Anderson, 1976; Morley, 1982; Anderson, 1983; FRIM, 1997; Giesen, 1998; Phillips and Bustin, 1998; Wust and Bustin, 1999). material (branches, roots, and stumps with bark) and variable quantities of sapric, Peats Peats from Malaysia, Indonesia, Irian Jaya or Thailand have large amounts of woody from Malaysia, Indonesia, Irian Jaya or Thailand have large amounts of woody amorphous matrix. The matrix contains residues and fragments of fungi, bacteria, plankton, sponges, fibres, leaves, roots, cuticles, epidermis, trichomes, spores and pollen. The predominantly forested tropical peat-forming environments result in wood-rich peat deposits, unlike most temperate peat deposits, which are often dominated by shrubs, grasses and bryophytes (Barber, 1993). Tropical peats are therefore often rich in lignin with only small amounts of hemicellulose, cellulose, protein, and water-soluble compounds (Polak, 1975; Orem et al., 1996; Kuder et al., 1998), which are lost due to vigorous microbial activity. It is commonly thought that woody peats generally result in bright, vitrain-rich coal (Taylor et al., 1998, p. 37) and peat derived from bryophytes or Cyperaceae produce dull coal. Well-humified, inertinite-rich or gelified organic deposits are thought to result in dull coals (Taylor et al., 1998, p. 292). A.A. 2 Tropical Tasek Bera - physiographic settings, peat accumulation and spatial distribution A.A.2.1 Peat Formation The wetland basin of Tasek Bera is located between the eastern and the western mountain ranges in Peninsular Malaysia and covers an area of 552 km2 at an altitude of 30 m above sea level (Fig. A-l). The dendritic, lowland basin occupies the largest natural freshwater lake system in Malaysia. The basin is covered by 300 km2 of rubber and oil palm plantations and 252 km of wetland and lowland rain forest. The basin measures 27 km from north to south and 13 km at its widest point. Peat accumulation is concentrated along the tributaries but is widespread in the central and northern part of the basin, where the water level is high year round (Fig. A-l). In the central and northern part, the water level is usually 20 to 100 cm above the soil surface. During El-Nino events (low precipitation, <100 mm/month), water levels may drop up to 50 cm below the peat surface, and water flow is restricted to the channels and lakes. Similar water level changes in mire systems have been documented from Kalimantan (Moore et al., 1996). Because of the high water retention of the peat, the organic-rich sediments are saturated during low water level periods and the water table away from the lake/channel system drops to a maximum depth of 15 cm below the sediment surface. The peaty topsoils in the southern tributaries may be exposed to air for several weeks during months of low precipitation. The basal deposits of the Holocene sedimentary basin that form the floor of the peat are composed of lateritic, kaolinite-rich massive clay, clay-rich quartz sand, and lesser amounts of clay-rich silt or sand. Radiocarbon data suggests that peat accumulation started some 5000 years BP in the tributaries of the central and southern Tasek Bera Basin (Wust and Bustin, 1999). Rising water levels, due to various factors, led to paludification of the northern part of the basin, and the vegetation community changed from a forested to a palm- (Pandanus spp.) and sedge-dominated environment (Lepironia spp., Eleocharis spp.). In the northern part of the basin, peat began accumulating approximately 4000 years BP. Since then, climatic and vegetational changes have led to terrestrialization of the lakes and channels within the wetland basin and to paludification of the deeply weathered, riparian lowland forest zone (Wust, 2001). Several micro-climatic changes led to vegetation changes and punctuated peat accumulation. Peat accumulation rates increased during times of abundant precipitation to maximum 2 mm/a, but decreased (to 0.6 mm/a) or ceased altogether during times of low precipitation (Wiist and Bustin, 1999). The undulating rate of peat accumulation caused changes in drainage (water level) and thus runoff, which has a major impact on peat preservation. In the Tasek Bera area, organic-rich deposits from the central and northern areas are often less than 3 m thick and have high ash contents (>20 wt-%), independent of the type of vegetation (swamp forest and Lepironia - Pandanus environment). In some southern swamp forest tributaries, such as in Paya Kuang or Paya Belinau, ash contents are low (<10 wt-%) and peat deposits are thick (2-6 m). The latter deposits are ombrotrophic with low nutrient levels (Wiist and Bustin, 1999). However, none of the deposits are ombrogenous. to Temertoh 57 km 5? 10.064 -02\u00C2\u00B0 30.681 N 3\u00C2\u00B0 08.49: E 102\u00C2\u00B0 32.( XelatungX, ty^t PAHANG DARULMAKMUR r23 km Paya 'Tasek ; 'Damparj Burung j Bankung Paya Belinau; NEGERI SEMStU DARUL KHUSUS Sungai Ayer lighway 11 Kuning Sungai Palong 12 km Eastern Watershed X Sungai to Temertoh 67 km Western Watershed Sungai Bera |~| raMkB*raS\u00C2\u00AB\u00C2\u00ABm lo Cempaka N 3\" 00.176 \u00C2\u00A3102\u00C2\u00B0 46.627 The Tasek Bera Basin 12.5 km 17.8 km to Keratong N 2\u00C2\u00B0 54.184 E 102\u00C2\u00B0 45.626 10 km . 6.2 miles ' Figure A-l: Location map of the Tasek Bera Basin (Tasek = lake) illustrating the dendritic drainage pattern, extent of peat accumulation (gray shading) and peat swamp tributary names (Paya = swamp, swampy area). Inset map shows the location of the Tasek Bera Basin in the states of Pahang and Negeri Sembilan, Peninsular Malaysia. Selected core sites are indicated. Sites B64 and B102 are from a Lepironia articulata and Pandanus helicopus environment, while site B83 is situated in true swamp forest. A.A.2.2 Climate Peninsular Malaysia is situated in the tropical zone and is characterised by high temperatures throughout the year, with an average of 30\u00C2\u00B0C in the lowlands. Precipitation in the vicinity of Tasek Bera is up to 2600 mm/a, with the average precipitation exceeding 2000 mm/a. However, fluctuations of more than 1000 mm can occur from year to year. During the 1992 and 1997 El-Nino years, Felda Bera (4 km southeast of TB Basin) and Felda Triang (10 km west of TB Basin) recorded seven and four months, and seven and six months, respectively, of low (below 100 mm/month) precipitation (Wiist and Bustin, 1999). The amount of rainfall peaks during the two monsoon seasons (Wiist and Bustin, 1999). Rainfall studies during field campaigns in 1997 and 1998 revealed that major wind changes (e.g. El-Nino, La Nina) influence the amount of precipitation drastically. From June to November 1997, the water level in the Tasek Bera lake fell below the top of the peat soils, causing widespread death of phytoplankton and compaction of the top organic soil layer. In the lowland forest and swamp forests, temperatures are generally lower, because the dense canopy provides microclimatic regulation, and net water loss due to evapotranspiration is lower than in open reed swamp areas, and so soil and understory vegetation are protected from drying out. A.A.2.3 Biological diversity of the Tasek Bera wetland Tasek Bera Basin is characterised by three main natural vegetation communities: dry lowland dipterocarp forest (trees dominated by Dipterocarpaceae), freshwater swamp forest, and freshwater lake system. The dry lowland dipterocarp forest can be subdivided into two groups: a dipterocarp-dominated area and a mixed-forest area. The dipterocarp forest, which covers the lowland hills bordering the swamp area, is dominated by various species such as Shorea spp., Dipterocarpus spp., and Koompassia spp. The mixed-forest is a transition between the high-ash freshwater swamp and the dipterocarp forest, and hosts species of both forest types. The freshwater lake system hosts three different sub-environments: 1) open water, limnic environment, with patches of open water (average depth of 2 m) connected by a complex of channels. The plant assemblages are mainly: Utricularia flexuosa, Nymphea sp., Cryptocorynepurpurea (in channels of forested areas), Batrachospermum spp. 2) A littoral or sedge marsh environment with an average water depth of 0.8 m, with a floral composition dominated by sedges and grasses including Lepironia articulata, Eleocharis ochrostachys, Zachinellia spp., Utricularia spp., and Limnanthemum spp. 3) A pandan-dominated environment along open water bodies and in areas less prone to desiccation during months of low precipitation dominated by Pandanus helicopus with subordinate Thoracostachyum sumatranum. The freshwater swamp forest environment is divisible into a high-ash and a low-ash freshwater peat forest and has a seasonally fluctuating water depth (Wiist and Bustin, 1999). High ash swamp forest is found mainly in the northern lowland drainage tributaries, such as Paya Kelatung, Paya Kemiyan, or Paya Tebuk (Fig. A-l). The vegetation is dominated by Eugenia spp., Tristania spp., Koompassia spp., Macaranga spp., Ficus spp., Pandanus atrocarpus, and Thoracostachyum sumatranum. High-ash peat deposits also occur in some tributaries in the southern part of the basin in the areas of confluence (e.g. northern part of Paya Tasek Dampar, Fig. A-l). The high-ash swamp forest has shorter (rarely taller than 25 m), slender trees with small, sparse open canopies compared to the dense and high canopy lowland forest (<50 m). The vegetation of the northern swamp forests differs from the low-ash freshwater swamp forest areas in the south such as Paya Tasek Dampar, Paya Belinau or Paya Kuang (Fig. A-l). The dominant species of the high-ash swamp forest, Eugenia spp., are subordinate and sometimes absent for several hundred metres in the southern low-ash peat swamps. Paya Belinau's dominant tree species are Pandanus atrocarpus, Cratoxylon arborescens, Cyrtostachys renda, and Macaranga puncticulata, with Thoracostachyum sumatranum and Ficus spp. as understory shrubs (Wiist and Bustin, 1999). A.A.3 Methods Three representative samples (core B64, B104 and B83) were collected for this study using a Macaulay corer. Stratigraphy was described in the field following the classification systems described in Esterle and Ferm (1990) and Wust (2001). Soil pH (Cardy\u00C2\u00AE Model C-l) and Munsell colours were determined. All samples were oven dried at 85\u00C2\u00B0 to 105\u00C2\u00B0C for four to seven days for determination of moisture content. Organic and ash contents were determined by weight loss on ignition after ashing at 750\u00C2\u00B0C for 2 to 4 hours. The mineralogical analyses of the peats of Tasek Bera illustrated that biogenic inorganic material contributes up to >75% of the total ash content (Wiist et al., 2002), which makes it impossible to quantify the detrital mineral matter of the peats. Organic carbon analyses were done on a Carlo Erba NA-1500 analyzer according to the analytical method of Verardo et al. (1990). The carbon content of B83 and B102 (Table A-l) was estimated according to the linear correlation of ash and carbon content as demonstrated in Wiist (2001). Polished blocks were prepared for petrographic analysis in reflected light. Representative samples from each of the macroscopically observable peat facies were selected for petrographic analysis. Bulk core sections were freeze-dried and impregnated with epoxy resin under vacuum (Epo-Thin\u00C2\u00AE, Buehler Technologies), and were subsequently polished using standard coal petrographic methods adapted for peats (e.g. Stach et al., 1982; Esterle et al., 1991). Fluorescent light was used to conduct organic petrographic point counts, while observations of mineral matter were made under white light. Results are reported as volume percentages (mineral matter free), and are based on a count of 300 points with a 0.2 mm step interval. A.A.4 Results and Discussion Three representative cores were selected from the sedge (site B64 and B102) and forest (site B83) mires. These peat deposits are autochthonous, as is evident from the peat stratigraphy. Most deposits have high macroscopic organic fibre contents that show little humification, which is typical for tropical peat deposits. Peat deposits from the tropics are also known to have higher lignin contents (e.g. textinite) in the basal peat than in the deposits towards the topsoil (Esterle, 1990). A.A.4.1 Pandanus and Lepironia environment (Sites B64 and B102) The site of B64 is located in a swamp dominated by Lepironia, Pandanus and sedges (Fig. A-l). The profile was water saturated at the time of sampling. Macroscopically, this profile (Fig. A-2) consists of a sapric to fine hemic surficial layer with abundant Lepironia roots and root fragments (0-60 cm). With increasing depth (60-100 cm), Pandanus roots become predominant. Below 100 cm, the presence of abundant woody fragments and leaves within a hemic matrix indicates that the locality was at one time a forested swamp. The profile grades into a lowland Dipterocarp forest (approximately 225 cm depth) with wood and woody fragments, and subsequently grades into an increasingly inorganic sediment consisting of sand and silt. The ash yield fluctuates throughout the profile and ranges between 30 and 60 wt-% in the peat deposits (Table A-l). The ash content is lowest during the time of deposition of peat in the swamp forest and increases towards the topsoil. Abundant textinite (35%) in the upper peat layer (37-45 cm) is composed mainly of live and minimally-humified root tissues, plus relatively unhumified material deposited at the surface (Fig. A-3). Textinite increases in the middle peat layer (102-110 cm) to 53%, most of which is comprised of large, intact woody fragments found in this horizon, and is still prevalent (33%) in the lowermost peat layer (220-228 cm). The humodetrinite content increases from 15% at the surface to 21% in the swamp forest peat facies, and declines to 4% in the dipterocarp forest facies. The high humodetrinite content at the surface is attributed to the high susceptibility of the surface vegetation to humification processes (i.e. the cellulose-rich sedges), while the humodetrinite within the swamp forest facies is consistent with an environment in which aerobic humification processes are the most significant diagenetic pathway. Texto-ulminite is a relatively minor constituent (6%), indicating that relatively little gelification (anaerobic diagenesis) has occurred. Corpohuminite is present in significant amounts (12%), indicating the presence of tannins within the peat. The relatively low carbon content (15%) found at the surface attests to the unaltered condition of much of the material making up the peat. The increase in carbon content with depth correlates with the increasing levels of humification. The majority of the liptinites consist of cutinite, resinite, liptodetrinite and suberinite. Due to the thermally immature nature of the peats, volatile oils within the plant structures are highly susceptible to reaction with the impregnating resin and with fluorescent light used in sample preparation, resulting in the formation of artifact \"resinites\" and \"exsudatinites\". These artifacts may, in part, account for the high \"resinite\" content within the 37-45 cm sample. Inertinite, consisting almost entirely of funginite, increases with increasing depth (2-21%). The presence of funginite indicates that aerobic conditions existed within the peat, as fungi are obligate aerobes (Brady and Weil, 1996). Figure A-2: Core B64 from Lepironia and Pandanus environment. The site was waterlogged at the time of core collection. Stratigraphic description and chemical characterization of the profile and petrographic composition. Petrographic results are reported on a volume percent basis. The huminites (vitrinites) are often dominant with various amounts of liptinites. Inertinites, mainly funginite, dominate the lower part of this littoral core. B64 Stratigraphy Munsell Characterization color N> UJ 0 -> 50 100 S. \u00C2\u00A9 150 Q 200 -250 J \u00C2\u00AB H I 3/2 4/1 3/2 5/2 7/1 abd roots ot Lepironia small, short root fragments abd roots ot Pandanus long fibers and roots ot Pandanus abd roots abd woody fragments, highly humified abd woody fragments, twigs, leaves woody fragments woody fragments and mud with sand and silt, organic fragments hemic fine hemic sapric organic rich mud a clay wood leaves UTTORAL PANDANUS AND SEDGE SWAMP SWAMP FOREST 50 -100 -150 -(abd = abundant) 2 0 0 -LOWLAND DIPTEROCARP FOREST 250 -3.5 roots Total moisture in wt-% C in wt-% 0 20 40 60 80 100 10152025303540 0 ' I L :/N ratii Carbon 7 0 20 40 60 80 100 10152025303540 0 HT-ash in wt-% C in wt-% r Petrographic analysis in vol-% 10 20 30 40 50 60 70 80 90 100 I I I I I I I I I I I ' M : \u00E2\u0080\u0094 0 20 30 Textinite ] Texto-Ulminite [HI Humodetrinite 80 90 100 Corpohuminite Liptinites Inertinites (Funginite) Site B102 is situated within a sedge marsh, similar to site B64 (Fig. A-l). The peat profile (Fig. A-3) is approximately 250 cm in depth, and records a vegetation history similar to that of B64. The sediment grades from white clay (7/1, 10YR) with few organic fragments at the base to an organic-rich mud with abundant short plant fragments and wood (216-219 cm). The mud is overlain by sapric and fine hemic peat (145-200 cm) with abundant plant fragments such as leaves, bark, charcoal, and wood (189-196 cm), as well as pandan fragments. Two fine hemic peat units with 100% pandan fragments (128-145 cm and 100-109 cm) are interbedded with a fine hemic peat (109-128 cm) with woody fragments and leaves. This interval is interpreted to have been deposited in a forest swamp environment. Above 30 cm, the peat has a clay-rich sapric matrix with abundant live Pandanus and Lepironia roots. The ash content of the peat deposits ranges from less than 20% to over 60% (Table A-l). Hence the carbon content fluctuates as well, with about 35% throughout most of the Textinite is less abundant in the upper portion of the profile (25%), increases to 67% in the 55-63 cm sample, and subsequently decreases to 16% in the 180-188 cm sample (Fig. A-4). Texto-ulminite increases consistently with depth, from 14-28%. Humodetrinite is consistent within the three uppermost samples (approximately 5%) but increases to 10% in the lowest sample. These trends indicate that in general, alteration of the peat increases with age, however the peat at the surface is more susceptible to alteration than the woody peat found at depth, and that conditions (water level, vegetation, climate) at the surface are not favourable to preservation. The majority of the liptinites present throughout the profile are liptodetrinites (up to 9%) and sporinites (up to 5%). Unlike the other profiles, semifusinite is present in significant amounts (up to 5% at site B102), indicating that fires have occurred in the past. Funginite is prevalent (4-20%), especially at the surface and in the lowermost sample, indicating that intermittent aerobic conditions prevailed. Figure A-3: Core B102 from Lepironia and Pandanus environment. The site was waterlogged at the time of core collection. Stratigraphic description and chemical characterization of the profile and petrographic composition. Petrographic results are reported on a volume percent basis. The huminites (vitrinites) are often dominant with various amounts of liptinites. Inertinites, mainly funginite, dominate the lower part of this littoral core. to B102 o 5 0 -\u00C2\u00A7 loo-ts. u 150-200-Stratigraphy Munsell color 3/1 3/1 2/2 2b0-> V V fibric s. s coarse hemic hemic fine hemic Characterization abd. roots of Pandanus, Lepironia abd. charcoal fragments abd. roots of Pandanus, Lepironia abd roots of Pandanus, Lepironia UTTORAL PANDANUS AND REED SWAMP WITH FOREST FIRES abd roots of Pandanus, Lepironia abd long roots of Pandanus, Lepironia abd roots of Pandanus (100%) no Lepironia \u00E2\u0080\u0094 abd. roots of Pandanus and woody fragments FOREST (leaves, bark) LITTORAL? abd. roots of Pandanus and woody fragments (leaves, bark, charcoal, roots, braches) abd. short, small woody fragments (roots, bark, leaves) abd organic fragments few, short organic fragments sapric ^ leaves organic rich mud roots clay (abd = abundant) SWAMP FOREST LOWLAND DIPTEROCARP FOREST wood Total moisture in wt-% Petrographic analysis in vol-% 0 20 40 60 80100 0 10 20 30 40 50 60 70 80 90 100 | Humodetrinite Inertinites (Funginite) Table A-l: Data analyses of the three representative cores of the Tasek Bera Basin for petrographic investigations. Core number, sample depth in cm, ash content in wt-%, carbon content in wt-% and pH are given. The carbon content of B83 and B102 was estimated based on the linear relationship between ash and carbon content of over 130 samples from the Tasek Bera mire (Wiist, 2001). deposit. r-N , 7 .c 102- 220-Depth in cm 37^45 1 1 Q 2 2 g 125- 220- 310- 435-J U 1 3 0 133 228 318 443 12-20 55-63 Vegetation type Sedges/pandan True Swamp Forest Sedges/pandan Ash content in wt.% Carbon content in wt.% (approx.) PH (H20) 48 44 35 23 25 30 4.7 4.6 4.5 12 5 8 8 8 >40 >45 >45 >45 >45 3.9 4 4.1 4.2 4.5 60 25 20 17 15 33 35 37 4.8 4.5 4.8 4.9 Core # B64 B83 B102 Petrographic analysis in vol.% Textinite Texto-Ulminite Humodetrinite/ Humogelinite Corpohuminite Cutinite Resinite Exsudatinite Suberinite Lipto-detrinite Sporinite Chlorophyllinite Fluorinite Funginite Other Inertinite 35.3 53 33.7 49.3 47.3 38.3 41.7 64.3 24.7 66.3 51 16 6 2.3 0.7 2.7 9.3 3 7.7 4 13.7 13.3 26.7 28.3 15.3 20.7 4.3 17 9.7 14.7 19 12.3 5 5.7 5.3 9.7 12.3 2.3 22.7 0.7 12 2.7 2.3 0.7 4.3 0 2.7 9 4.3 6 3.7 3.7 7.7 3 2.7 0.3 6 3 1.3 4.7 18 0 0.3 1 1.7 2.3 3.3 2.3 0 0 0.7 1.7 0 0 1.7 0 0 0.7 4.7 0 4.3 0 0.7 0.3 1.7 0.7 1.3 0.7 2.7 4 0.3 0.7 1.3 1.3 0.7 1.3 2.3 1.3 6 5 3.3 6 7 5.3 9 4.3 2.7 4 1.3 1 2 7 0 2.7 2.3 1.3 5 1 0.3 2.7 0 0 0.3 0.7 0 0 0.3 0 0.3 0 0 0 1.7 2.3 1.7 0.7 0 0 0 0.7 0.7 0.7 0 0.3 1.7 10.3 21.3 11.3 5.7 23.3 8.7 8 21 4 6.3 21 0 0 0.3 0.3 0.7 0 0 0 4.7 0.3 1.7 1 A.A.4.2 Swamp Forest Environment (Site B83) Sampling site B83 is located within a low-ash, ombrotrophic swamp forest (Fig. A-l). The profile (Fig. A-4) consists of hemic to fine hemic peat in the uppermost 150 cm, underlain by hemic to sapric peat to a depth of approximately 520 cm. The contact with the mineral sediment grades from organic-rich mud to clay at 560 cm. Abundant small woody fragments, leaves and roots in varying stages of preservation are embedded within the peat matrix throughout the profile. Ash content is often less than 10% and carbon content exceeds 40 to 45% (Table A-l). Textinite is the most abundant maceral throughout the profile, ranging from 38-68% (Fig. A-5). In the surficial horizon (30-38 cm), much of this textinite is derived from roots, while at depth the abundant woody fragments are the major source. Texto-ulminite is present in much smaller amounts, ranging from 3-9%, indicating a lack of anaerobic bacterial alteration processes that have affected the peat. Humodetrinite ranges from 10-23%, and is usually found agglomerated with the clay minerals, diatoms and sponge spicules that make up much of the hemic to sapric matrix. Corpohuminite is present only in limited amounts in most of the samples (less than 1-12%). Liptinites consist mainly of cutinite, liptodetrinite, suberinite, and sporinite, consistent with a hemic to sapric peat derived from wood and leaves. Inertinite is almost exclusively funginite, and ranges from 5-23%. The high funginite content is indicative of intermittent aerobic conditions throughout the depositional history of the peat. Figure A-4: Core B83 from the swamp forest environment of Paya Belinau (Fig. 1). The site was waterlogged at the time of core collection. Stratigraphic description and chemical characterization of the profile and petrographic composition. Petrographic results are reported on a volume percent basis. The huminites (vitrinites) are often dominant with various amounts of liptinites. Inertinites, mainly funginite, dominate the middle part of the swamp forest deposits. K> OJ Stratigraphy Munsell Characterization color 2/2 pH Total moisture in wt-% 3.5 4.0 4.5 5.0 0 20 40 60 80100 0 abd roots ot Lepironia small, short root fragments Petrographic analysis in vol-% 10 20 30 40 50 60 70 80 90 100 I I I I I I abd long roots of Pandanus long fibers and roots, woody long fibers, woody fragments leaves, bark 2.5/2 woody fragments, leaves, bark (5YR) small woody fragments, fibers, wood highly degraded, abd small woody fragments abd fibers highly degraded, abd small woody fragments abd woody fragments dense, abd. woody fragments highly degraded, roots, leaves, bark dense, abd. woody fragments highly degraded, roots, leaves, bark organic-rich mud abd charcoal fragments with sand 100 SWAMP FOREST 300 fine hemic ^ coarse hemic [JJJ sapric E/J5 hemic \u00E2\u0080\u00A2 organic rich mud LOWLAND 5 5 0 DIPTEROCARP FOREST 600 clay 3.75 4.25 4.75 wood roots leaves (abd = abundant) 0 10 20 30 40 50 60 70 80 90 100 Textinite g Corpohuminite Liptinites \u00E2\u0080\u00A2 Inertinites (Funginite) 0 20 40 60 80100 HT-ash in wt-% A.A.4.3 Maceral Ratio Diagrams Maceral ratios for interpretation of peat depositional environments are based on the concept of diagnostic macerals, which are either plant- or environment-specific (e.g. Diessel, 1982). The textinite plus texto-ulminite content versus the inertinite content is commonly assumed to delineate peat deposited under prevailing anaerobic versus aerobic conditions because the texto-ulminite content requires anaerobic or low-aerobic conditions, while the inertinite often indicates fires, drought or microbial activities. For site B64, inertinite increases with depth (Fig. A-5a). This suggests that anaerobic conditions prevailed during deposition of the uppermost peat, but that aerobic conditions were more common during the formation of the peat that is found at lower positions within the profile. Dissolved oxygen measurements (Wiist and Bustin, 1999) show that perennial high water levels prohibit aeration of the uppermost peat deposits. Changing water levels in the past on an annual or decade scale (water level fluctuations during monsoon and inter-monsoon time) could have resulted in periodic exposure of the peat surface at site B64 (e.g. Wiist and Bustin, 1999). In contrast to the perennial flooded site B64, the uppermost 7 to 10 cm of the peat deposits at core site B102 were above the water level during the El-Nino in 1998. For site B102, the textinite plus texto-ulminite content is relatively constant, whereas the inertinite (mainly funginite) content is highest in the surface horizon, lowest in the 55-63 cm sample and then gradually increases with depth in the remainder of the profile. This suggests that aerobic conditions have recently developed within the upper portion of the profile, while the peats below have been subject to intermittent oxidation. The swamp forest peat (B83, Fig. A-4) shows no pattern of variability with depth, indicating that conditions within the profile fluctuated substantially over time and that no simple conclusions can be drawn from using maceral ratios in this case.The results from this study plotted in maceral ratio diagrams produce mixed results (Fig. A-5b). Although sites B102 and B64 represent similar environments in terms of vegetation and hydrology, the plots suggests very dissimilar environments. TPI's for site B102 are generally much higher than those obtained for site B64, while GI's are similar, with the exception of the highly gelified basal peat, and to a lesser extent, surface peat, of profile B102 (Fig. A-5b). A similar pattern (as TPI and GI) emerges when texto-ulminite is cross-plotted with inertinite (Fig. A-5c). The B102 profile shows that both parameters increase concurrently with depth, with the exception of the surface sample, which is very high in inertinite, whereas in the B64 profile, the texto-ulminite content decreases with increasing inertinite content and increasing depth. The B83 profile does not show any clear pattern in maceral content variation with depth, similar to the other cross plots. A comparison of the results from these cross plots illustrates some of the problems inherent to the use of maceral ratio diagrams to determine paleodepositional environments. Although B64 (Fig. A-2) and B102 (Fig. A-3) are similar vegetational environments at the present time and have similar macroscopic peat compositions (Fig. A-2,7-3), the results are quite different (Table A-l), suggesting that the two sites have been subjected to differing postdepositional factors that control early diagenetic processes. For example, periodic drying of the profile and subsequent colonisation by fungi, or fires in the nearby dipterocarp forest, swamp forest or Pandanus helicopus, result in increased inertinite contents. During peatification and coalification, most of the readily hydrolysable substances of the plants are lost, such as cellulose and hemicellulose, while the humic substances become concentrated (Taylor et al., 1998). As a result of the differing early diagenetic pathways, original organic petrographic features of the profiles, derived, for example, from the vegetation type, are overprinted. The organic petrographic characteristics become increasingly divergent as time and diagenesis progress, resulting in coals that are entirely dissimilar. In addition, secondary alteration processes occur after burial and further alter the maceral composition of peat deposits, rendering maceral ratios almost useless. .\u00E2\u0080\u00A2ti c "Thesis/Dissertation"@en . "2004-05"@en . "10.14288/1.0052634"@en . "eng"@en . "Oceanography"@en . "Vancouver : University of British Columbia Library"@en . "University of British Columbia"@en . "For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use."@en . "Graduate"@en . "Elemental characteristics of organic deposits from an area surrounding a lead-zinc smelter : concentration, distribution, mode of occurrence and mobility"@en . "Text"@en . "http://hdl.handle.net/2429/17082"@en .