Britt Hall - Academia.edu (original) (raw)

Papers by Britt Hall

Research paper thumbnail of Food as the Dominant Pathway of Methylmercury Uptake by Fish

Water, Air, and Soil Pollution, 1997

A field experiment was conducted to determine the degree to which fish accumulated methylmercury ... more A field experiment was conducted to determine the degree to which fish accumulated methylmercury (MeHg) via their food or via passive uptake from water through the gills. Finescale dace (Phoxinus neogaeus) were held in 2000 L enclosed pens floating in an undisturbed, oligotrophic lake in northwestern Ontario. Fish were exposed to water containing either low (0.10-0.40 ng L 1), intermediate (0.45-1.30 ng L 1), or high (0.80-2.1 ng L 1) concentrations of MeHg. Zooplankton with either low (0.16-0.18 g g 1 d.w.) or high (0.28-0.76 g g 1 d.w.) concentrations of MeHg were added daily to each pen. Fish fed zooplankton with high concentrations of MeHg had significantly higher concentrations of mercury in muscle after 32 days than fish fed zooplankton with low concentrations of MeHg (ANCOVA, P<0.0001). Fish feeding on zooplankton with low concentrations of MeHg had the same amount of Hg in their tissues as fish at the start of the experiment. Uptake from water was at most 15%. This is the first experiment to confirm that food is the dominant pathway of MeHg bioaccumulation in fish at natural levels of MeHg.

Research paper thumbnail of Mercury Elevator in Lakes: A Novel Vector of Methylmercury Transfer to Fish via Migratory Invertebrates

Research paper thumbnail of Mercury exposure to red-winged blackbirds (Agelaius phoeniceus) and dragonfly (Odonata: Aeshnidae) nymphs in Prairie Pothole wetlands

FACETS

The Prairie Pothole Region (PPR) in the northern Great Plains is an area of ecological significan... more The Prairie Pothole Region (PPR) in the northern Great Plains is an area of ecological significance, serving as an important breeding site for avian wildlife. However, organisms feeding within the PPR may be at risk of mercury (Hg) exposure due to deposition of anthropogenic emissions and the high Hg methylation potential of PPR wetlands. We quantified Hg concentrations in red-winged blackbirds’ ( Agelaius phoeniceus (Linnaeus, 1766); RWBLs) blood, feathers, and eggs in the spring and summer breeding season and compared our values with those from RWBLs sampled from ecoregions across North America. Hg concentrations in whole water, aeshnid dragonfly nymphs, and RWBL tissues varied by wetland and were below those considered to elicit acute effects in wildlife, and egg total Hg (THg) concentrations were significantly related to spring whole water methylmercury concentrations. Only RWBL blood THg concentrations showed a clear increase in summer compared with spring, resulting in decoupl...

Research paper thumbnail of Habitat specificity is not universal proxy for sensitivity to habitat conversion among rodents on the Canadian Prairies

Converting habitat for agricultural production threatens biodiversity loss worldwide and has sign... more Converting habitat for agricultural production threatens biodiversity loss worldwide and has significant implications for human well-being. Debates on how to conserve biodiversity as the demand for agriculture products rises is being informed by studies using habitat specificity as a proxy for sensitivity to land modification, assuming all species respond to habitat loss and fragmentation relative to their affinity towards the habitat type being converted. Here, we test this assumption among rodent assemblages on the Canadian Prairies, hypothesizing negative responses among grassland obligates and neutral or positive responses among habitat generalists to landscape change along a gradient of increasing agricultural intensity. We found complex, sometimes contradictory responses among rodent species, which depended on the magnitude of habitat loss that had occurred and did not always reflect each species relative affinity for grassland habitat. Our results suggest future studies shoul...

Research paper thumbnail of Spatial analysis of a hydrocarbon waste‐remediating landfarm demonstrates influence of management practices on bacterial and fungal community structure

Microbial Biotechnology

Cultivation of dedicated soil plots called 'landfarms' is an effective technology for bioremediat... more Cultivation of dedicated soil plots called 'landfarms' is an effective technology for bioremediation of hydrocarbon waste generated by various industrial practices. To understand the influence of soil conditions on landfarm microbial communities, analysis of bacterial and fungal community structure using nextgeneration sequencing at different sections and depths was performed across a hydrocarbon-waste landfarm in Regina, Saskatchewan, Canada. While a core set of hydrocarbon-associated bacterial and fungal taxa are present throughout the landfarm, unique bacterial and fungal operational taxonomic units are differentially abundant at sections within the landfarm, which correlate with differences in soil physiochemical properties and management practices. Increased frequency of waste application resulted in strong positive correlations between bacterial community assemblages and elevated amounts of oil, grease and F3-F4 hydrocarbon fractions. In areas of standing water and lower application of hydrocarbon, microbial community structure correlated with soil pH, trace nutrients and metals. Overall, diversity and structure of bacterial communities remain relatively stable across the landfarm, while in contrast, fungal community structure appears more responsive to soil oxygen conditions. Results are consistent with the hypothesis that years of bioremediation activity have shaped microbial communities; however, several management practices can be undertaken to increase efficiency of remediation, including the removal of standing water and soil tilling across the landfarm.

Research paper thumbnail of Trapped river otters (Lontra canadensis) from central Saskatchewan differ in total and organic mercury concentrations by sex and geographic location

FACETS

Mercury (Hg) in wildlife remains of great concern, especially for apex piscivores. Despite this, ... more Mercury (Hg) in wildlife remains of great concern, especially for apex piscivores. Despite this, exposure information from many species in many areas is lacking, so that management decisions are hampered. Here we examine Hg concentrations in fur, liver, and kidney tissues from river otters ( Lontra canadensis (Schreber, 1777)) ( n = 203) to quantify existing Hg concentrations over a broad geographic area in Saskatchewan. Mean fur total Hg (THg) (9.68 ± 7.52 mg/kg fresh weight (f.w.)) was significantly correlated with THg and organic Hg (OHg) in liver and kidney tissue, showcasing the potential for using fur as a noninvasive method of monitoring Hg in top-level mammals. Livers of males had higher mean OHg concentrations than livers of females (males: 2.71 mg/kg d.w., females: 1.87 mg/kg d.w.), but not significantly so. No sex-related differences were observed in kidney OHg concentrations. THg concentrations in otter fur collected in the Boreal Shield ecozone (Churchill River Upland) ...

Research paper thumbnail of Multidecadal carbon sequestration in a headwater boreal lake

Limnology and Oceanography

Dissolved organic carbon (DOC) was measured continuously since 1970 in a pristine headwater borea... more Dissolved organic carbon (DOC) was measured continuously since 1970 in a pristine headwater boreal lake and its catchment at the IISD-Experimental Lakes Area (Ontario, Canada). Mass balanced accounting of DOC concentrations in precipitation, watershed runoff, and inflow and outflow streams, and integrated weekly hydrological data determined annual mass flux of DOC to and from the lake. Inputs minus outputs represented two residual terms: (1) mineralization and evasion of CO 2 and (2) DOC flocculation and sediment burial. Accumulation of organic carbon in sediment cores estimated permanent storage and evasion was calculated by subtraction of burial from the annual retention over 40 yr (1971-2010). Terrestrial sources accounted for 92% AE 1% of DOC load; 37% AE 2% of which was lost via the outflow. About 40% AE 3% of DOC load accumulated in sediments and 23 AE 3% was lost as CO 2. Over 40 yr, C sequestration in sediments was a more important sink than evasion or outflow. We explore the fate of DOC during decade long periods of differing precipitation patterns. Loading and loss via the outflow was higher in wet (1990-2010) compared to dry (1980-1990) years. Due to longer DOC processing times when water residence times are longer, it is possible that if drought increases in the boreal forest, the efficiency of headwater lakes to sequester C in sediments maybe greater than in wet periods.

Research paper thumbnail of Recent advances in the study of mercury methylation in aquatic systems

FACETS

With increasing input of neurotoxic mercury to environments as a result of anthropogenic activity... more With increasing input of neurotoxic mercury to environments as a result of anthropogenic activity, it has become imperative to examine how mercury may enter biotic systems through its methylation to bioavailable forms in aquatic environments. Recent development of stable isotope-based methods in methylation studies has enabled a better understanding of the factors controlling methylation in aquatic systems. In addition, the identification and tracking of the hgcAB gene cluster, which is necessary for methylation, has broadened the range of known methylators and methylation-conducive environments. Study of abiotic factors in methylation with new molecular methods (the use of stable isotopes and genomic methods) has helped elucidate the confounding influences of many environmental factors, as these methods enable the examination of their direct effects instead of merely correlative observations. Such developments will be helpful in the finer characterization of mercury biogeochemical ...

Research paper thumbnail of Mercury and methylmercury in aquatic sediment across western North America

Science of The Total Environment, 2016

concentrations of aquatic sediment compiled from >11000 sites across western NA  Geospatial attr... more concentrations of aquatic sediment compiled from >11000 sites across western NA  Geospatial attributes were integrated with Hg and MeHg concentrations  MeHg concentrations differed among landscape categories, trends differed from THg  THg-MeHg relationship was weak (r 2 = 0.25) but significant across the landscape  51% of MeHg variation explained by within-site variability and landscape categories

Research paper thumbnail of Methylmercury and Total Mercury in Plant Lifter Decomposing in Upland Forests and Flooded Landscapes

Environmental Science Technology, 2004

Research paper thumbnail of Effects of in-channel beaver impoundments on mercury bioaccumulation in Rocky Mountain stream food webs

Research paper thumbnail of Bioaccumulation of mercury in the aquatic food chain in newly flooded areas

Metal ions in biological systems

Research paper thumbnail of Ecotoxicology 2014 Clayden et al Supplementary Info

Research paper thumbnail of Mercury methylation in high and low-sulphate impacted wetland ponds within the prairie pothole region of North America

Environmental Pollution, 2015

How to cite TSpace items Always cite the published version, so the author(s) will receive recogni... more How to cite TSpace items Always cite the published version, so the author(s) will receive recognition through services that track citation counts, e.g. Scopus. If you need to cite the page number of the author manuscript from TSpace because you cannot access the published version, then cite the TSpace version in addition to the published version using the permanent URI (handle) found on the record page.

Research paper thumbnail of Mercury Concentrations in Surface Water and Harvested Waterfowl from the Prairie Pothole Region of Saskatchewan

Environmental Science & Technology, 2009

Mercury cycling in prairie ecosystems is poorly understood. We examined methylmercury (MeHg) conc... more Mercury cycling in prairie ecosystems is poorly understood. We examined methylmercury (MeHg) concentrations in whole water from 49 diverse prairie wetlands and lakes in Saskatchewan. We also determined total Hg (THg) concentrations in waterfowl harvested by hunters for consumption. Average whole water MeHg concentrations ranged from 0.02 to over 4 ng L(-1) and were higher in water from wetland ponds compared to those in lakes. High MeHg concentrations in prairie wetlands present the possibility of increased Hg concentrations in biota inhabiting these and other similar systems. We therefore measured THg in 72 birds representing 13 species of waterfowl that commonly use prairie aquatic habitats. A large range in THg concentrations was observed among individual birds, with values ranging from below the detection limit to over 435 ng g(-1). When waterfowl were classified according to diet, we observed clear evidence of THg biomagnification with increasing proportion of animal prey consumed. THg concentrations in waterfowl collected by hunters did not exceed consumption guidelines of 0.5 mg kg(-1) developed for fish. This is the first study that has reported MeHg concentrations in water from the prairie pothole region of southern Saskatchewan.

Research paper thumbnail of Peer Reviewed: Experimenting with Hydroelectric Reservoirs

Environmental Science & Technology, 2004

Research paper thumbnail of Long-Term Wet and Dry Deposition of Total and Methyl Mercury in the Remote Boreal Ecoregion of Canada

Environmental Science & Technology, 2008

The purpose of the METAALICUS experiment was to examine the timing and magnitude of the response ... more The purpose of the METAALICUS experiment was to examine the timing and magnitude of the response of fish Hg concentrations to changes in atmospheric Hg loading. Enriched stable Hg isotopes were applied as HgNO 3 to the lake (202 Hg), wetland (198 Hg) and upland (200 Hg) compartments of the L658 watershed at ~22 ug m-2 yr-1 since 2001 (1, 2). However, the present study focused on deposition of ambient Hg, not the experimentally-applied isotopic Hg. Analytical Methods Precipitation and throughfall samples collected between 1992 and 2000 were analysed for total Hg (THg; all forms of Hg in a sample) using EPA Method 1631 (3) by Flett Research Ltd. (Winnipeg, MB). Briefly, all Hg in samples was oxidized to Hg(II) by the addition of BrCl, reduced to Hg(0) using SnCl 2 , purged onto gold traps, thermally desorbed and analyzed by cold vapour atomic fluorescence spectrometry (CVAFS). Samples collected in the METAALICUS watershed between 2001 and 2006 were analysed using inductively coupled plasma mass spectrometry (ICP-MS, 4, 5). Because ICP-MS quantifies concentrations of individual Hg isotopes, it was possible to distinguish concentrations of ambient Hg from the experimentally loaded enriched Hg isotopes. To calculate concentrations of ambient Hg, an isotope that was not experimentally applied to the watershed was used as an ambient Hg surrogate (199 Hg). Samples collected in 2001-2004 were analyzed at the Trent University Worsfold Water Quality Center (Peterborough, ON). Samples were continuously mixed in-line with SnCl 2 using peristaltic pumps, and the reduced gaseous Hg(0) formed was separated in a custom-made gas/liquid separator and swept into the plasma of a Finnigan Element 2 ICP-MS (6). For samples collected between 2005 and 2006, analysis was completed at the University of Alberta Biogeochemical Laboratory (Edmonton, AB). In this laboratory, reduction of Hg and gas/liquid separation was accomplished using an automated Tekran 2600 total Hg analyzer interfaced with a PerkinElmer Elan DRC-e ICP-MS for detection. Precipitation and throughfall samples collected for methylmercury (MeHg) analyses prior to 2001 were distilled, ethylated by additions of sodium tetra-ethyl-borate (NaBEt 4), and volatile Hg species were purged and trapped using either carbo or tenax traps. Samples were thermally desorbed and separated by gas chromatography before quantification by CVAFS (7, 8). Samples collected in the METAALICUS watershed were analyzed for MeHg as described above, except that

Research paper thumbnail of Methylmercury and Total Mercury in Plant Litter Decomposing in Upland Forests and Flooded Landscapes

Environmental Science & Technology, 2004

Research paper thumbnail of Response | Mercury and the FLUDEX project

Environmental Science & Technology, 2005

Research paper thumbnail of Concentrations of methylmercury in invertebrates from wetlands of the Prairie Pothole Region of North America

Environmental Pollution, 2012

Prairie wetlands may be important sites of mercury (Hg) methylation resulting in elevated methylm... more Prairie wetlands may be important sites of mercury (Hg) methylation resulting in elevated methylmercury (MeHg) concentrations in water, sediments and biota. Invertebrates are an important food resource and may act as an indicator of MeHg exposure to higher organisms. In 2007e2008, invertebrates were collected from wetland ponds in central Saskatchewan, categorized into functional feeding groups (FFGs) and analyzed for total Hg (THg) and MeHg. Methylmercury and THg concentrations in four FFGs ranged from 0.2e393.5 ng$g À1 and 9.7e507.1 ng$g À1 , respectively. Methylmercury concentrations generally increased from gastropods with significantly lower average MeHg concentrations compared to other invertebrate taxa. Surrounding land use (agricultural, grassland and organic agricultural) may influence MeHg concentrations in invertebrates, with invertebrate MeHg concentrations being higher from organic ponds (457.

Research paper thumbnail of Food as the Dominant Pathway of Methylmercury Uptake by Fish

Water, Air, and Soil Pollution, 1997

A field experiment was conducted to determine the degree to which fish accumulated methylmercury ... more A field experiment was conducted to determine the degree to which fish accumulated methylmercury (MeHg) via their food or via passive uptake from water through the gills. Finescale dace (Phoxinus neogaeus) were held in 2000 L enclosed pens floating in an undisturbed, oligotrophic lake in northwestern Ontario. Fish were exposed to water containing either low (0.10-0.40 ng L 1), intermediate (0.45-1.30 ng L 1), or high (0.80-2.1 ng L 1) concentrations of MeHg. Zooplankton with either low (0.16-0.18 g g 1 d.w.) or high (0.28-0.76 g g 1 d.w.) concentrations of MeHg were added daily to each pen. Fish fed zooplankton with high concentrations of MeHg had significantly higher concentrations of mercury in muscle after 32 days than fish fed zooplankton with low concentrations of MeHg (ANCOVA, P<0.0001). Fish feeding on zooplankton with low concentrations of MeHg had the same amount of Hg in their tissues as fish at the start of the experiment. Uptake from water was at most 15%. This is the first experiment to confirm that food is the dominant pathway of MeHg bioaccumulation in fish at natural levels of MeHg.

Research paper thumbnail of Mercury Elevator in Lakes: A Novel Vector of Methylmercury Transfer to Fish via Migratory Invertebrates

Research paper thumbnail of Mercury exposure to red-winged blackbirds (Agelaius phoeniceus) and dragonfly (Odonata: Aeshnidae) nymphs in Prairie Pothole wetlands

FACETS

The Prairie Pothole Region (PPR) in the northern Great Plains is an area of ecological significan... more The Prairie Pothole Region (PPR) in the northern Great Plains is an area of ecological significance, serving as an important breeding site for avian wildlife. However, organisms feeding within the PPR may be at risk of mercury (Hg) exposure due to deposition of anthropogenic emissions and the high Hg methylation potential of PPR wetlands. We quantified Hg concentrations in red-winged blackbirds’ ( Agelaius phoeniceus (Linnaeus, 1766); RWBLs) blood, feathers, and eggs in the spring and summer breeding season and compared our values with those from RWBLs sampled from ecoregions across North America. Hg concentrations in whole water, aeshnid dragonfly nymphs, and RWBL tissues varied by wetland and were below those considered to elicit acute effects in wildlife, and egg total Hg (THg) concentrations were significantly related to spring whole water methylmercury concentrations. Only RWBL blood THg concentrations showed a clear increase in summer compared with spring, resulting in decoupl...

Research paper thumbnail of Habitat specificity is not universal proxy for sensitivity to habitat conversion among rodents on the Canadian Prairies

Converting habitat for agricultural production threatens biodiversity loss worldwide and has sign... more Converting habitat for agricultural production threatens biodiversity loss worldwide and has significant implications for human well-being. Debates on how to conserve biodiversity as the demand for agriculture products rises is being informed by studies using habitat specificity as a proxy for sensitivity to land modification, assuming all species respond to habitat loss and fragmentation relative to their affinity towards the habitat type being converted. Here, we test this assumption among rodent assemblages on the Canadian Prairies, hypothesizing negative responses among grassland obligates and neutral or positive responses among habitat generalists to landscape change along a gradient of increasing agricultural intensity. We found complex, sometimes contradictory responses among rodent species, which depended on the magnitude of habitat loss that had occurred and did not always reflect each species relative affinity for grassland habitat. Our results suggest future studies shoul...

Research paper thumbnail of Spatial analysis of a hydrocarbon waste‐remediating landfarm demonstrates influence of management practices on bacterial and fungal community structure

Microbial Biotechnology

Cultivation of dedicated soil plots called 'landfarms' is an effective technology for bioremediat... more Cultivation of dedicated soil plots called 'landfarms' is an effective technology for bioremediation of hydrocarbon waste generated by various industrial practices. To understand the influence of soil conditions on landfarm microbial communities, analysis of bacterial and fungal community structure using nextgeneration sequencing at different sections and depths was performed across a hydrocarbon-waste landfarm in Regina, Saskatchewan, Canada. While a core set of hydrocarbon-associated bacterial and fungal taxa are present throughout the landfarm, unique bacterial and fungal operational taxonomic units are differentially abundant at sections within the landfarm, which correlate with differences in soil physiochemical properties and management practices. Increased frequency of waste application resulted in strong positive correlations between bacterial community assemblages and elevated amounts of oil, grease and F3-F4 hydrocarbon fractions. In areas of standing water and lower application of hydrocarbon, microbial community structure correlated with soil pH, trace nutrients and metals. Overall, diversity and structure of bacterial communities remain relatively stable across the landfarm, while in contrast, fungal community structure appears more responsive to soil oxygen conditions. Results are consistent with the hypothesis that years of bioremediation activity have shaped microbial communities; however, several management practices can be undertaken to increase efficiency of remediation, including the removal of standing water and soil tilling across the landfarm.

Research paper thumbnail of Trapped river otters (Lontra canadensis) from central Saskatchewan differ in total and organic mercury concentrations by sex and geographic location

FACETS

Mercury (Hg) in wildlife remains of great concern, especially for apex piscivores. Despite this, ... more Mercury (Hg) in wildlife remains of great concern, especially for apex piscivores. Despite this, exposure information from many species in many areas is lacking, so that management decisions are hampered. Here we examine Hg concentrations in fur, liver, and kidney tissues from river otters ( Lontra canadensis (Schreber, 1777)) ( n = 203) to quantify existing Hg concentrations over a broad geographic area in Saskatchewan. Mean fur total Hg (THg) (9.68 ± 7.52 mg/kg fresh weight (f.w.)) was significantly correlated with THg and organic Hg (OHg) in liver and kidney tissue, showcasing the potential for using fur as a noninvasive method of monitoring Hg in top-level mammals. Livers of males had higher mean OHg concentrations than livers of females (males: 2.71 mg/kg d.w., females: 1.87 mg/kg d.w.), but not significantly so. No sex-related differences were observed in kidney OHg concentrations. THg concentrations in otter fur collected in the Boreal Shield ecozone (Churchill River Upland) ...

Research paper thumbnail of Multidecadal carbon sequestration in a headwater boreal lake

Limnology and Oceanography

Dissolved organic carbon (DOC) was measured continuously since 1970 in a pristine headwater borea... more Dissolved organic carbon (DOC) was measured continuously since 1970 in a pristine headwater boreal lake and its catchment at the IISD-Experimental Lakes Area (Ontario, Canada). Mass balanced accounting of DOC concentrations in precipitation, watershed runoff, and inflow and outflow streams, and integrated weekly hydrological data determined annual mass flux of DOC to and from the lake. Inputs minus outputs represented two residual terms: (1) mineralization and evasion of CO 2 and (2) DOC flocculation and sediment burial. Accumulation of organic carbon in sediment cores estimated permanent storage and evasion was calculated by subtraction of burial from the annual retention over 40 yr (1971-2010). Terrestrial sources accounted for 92% AE 1% of DOC load; 37% AE 2% of which was lost via the outflow. About 40% AE 3% of DOC load accumulated in sediments and 23 AE 3% was lost as CO 2. Over 40 yr, C sequestration in sediments was a more important sink than evasion or outflow. We explore the fate of DOC during decade long periods of differing precipitation patterns. Loading and loss via the outflow was higher in wet (1990-2010) compared to dry (1980-1990) years. Due to longer DOC processing times when water residence times are longer, it is possible that if drought increases in the boreal forest, the efficiency of headwater lakes to sequester C in sediments maybe greater than in wet periods.

Research paper thumbnail of Recent advances in the study of mercury methylation in aquatic systems

FACETS

With increasing input of neurotoxic mercury to environments as a result of anthropogenic activity... more With increasing input of neurotoxic mercury to environments as a result of anthropogenic activity, it has become imperative to examine how mercury may enter biotic systems through its methylation to bioavailable forms in aquatic environments. Recent development of stable isotope-based methods in methylation studies has enabled a better understanding of the factors controlling methylation in aquatic systems. In addition, the identification and tracking of the hgcAB gene cluster, which is necessary for methylation, has broadened the range of known methylators and methylation-conducive environments. Study of abiotic factors in methylation with new molecular methods (the use of stable isotopes and genomic methods) has helped elucidate the confounding influences of many environmental factors, as these methods enable the examination of their direct effects instead of merely correlative observations. Such developments will be helpful in the finer characterization of mercury biogeochemical ...

Research paper thumbnail of Mercury and methylmercury in aquatic sediment across western North America

Science of The Total Environment, 2016

concentrations of aquatic sediment compiled from >11000 sites across western NA  Geospatial attr... more concentrations of aquatic sediment compiled from >11000 sites across western NA  Geospatial attributes were integrated with Hg and MeHg concentrations  MeHg concentrations differed among landscape categories, trends differed from THg  THg-MeHg relationship was weak (r 2 = 0.25) but significant across the landscape  51% of MeHg variation explained by within-site variability and landscape categories

Research paper thumbnail of Methylmercury and Total Mercury in Plant Lifter Decomposing in Upland Forests and Flooded Landscapes

Environmental Science Technology, 2004

Research paper thumbnail of Effects of in-channel beaver impoundments on mercury bioaccumulation in Rocky Mountain stream food webs

Research paper thumbnail of Bioaccumulation of mercury in the aquatic food chain in newly flooded areas

Metal ions in biological systems

Research paper thumbnail of Ecotoxicology 2014 Clayden et al Supplementary Info

Research paper thumbnail of Mercury methylation in high and low-sulphate impacted wetland ponds within the prairie pothole region of North America

Environmental Pollution, 2015

How to cite TSpace items Always cite the published version, so the author(s) will receive recogni... more How to cite TSpace items Always cite the published version, so the author(s) will receive recognition through services that track citation counts, e.g. Scopus. If you need to cite the page number of the author manuscript from TSpace because you cannot access the published version, then cite the TSpace version in addition to the published version using the permanent URI (handle) found on the record page.

Research paper thumbnail of Mercury Concentrations in Surface Water and Harvested Waterfowl from the Prairie Pothole Region of Saskatchewan

Environmental Science & Technology, 2009

Mercury cycling in prairie ecosystems is poorly understood. We examined methylmercury (MeHg) conc... more Mercury cycling in prairie ecosystems is poorly understood. We examined methylmercury (MeHg) concentrations in whole water from 49 diverse prairie wetlands and lakes in Saskatchewan. We also determined total Hg (THg) concentrations in waterfowl harvested by hunters for consumption. Average whole water MeHg concentrations ranged from 0.02 to over 4 ng L(-1) and were higher in water from wetland ponds compared to those in lakes. High MeHg concentrations in prairie wetlands present the possibility of increased Hg concentrations in biota inhabiting these and other similar systems. We therefore measured THg in 72 birds representing 13 species of waterfowl that commonly use prairie aquatic habitats. A large range in THg concentrations was observed among individual birds, with values ranging from below the detection limit to over 435 ng g(-1). When waterfowl were classified according to diet, we observed clear evidence of THg biomagnification with increasing proportion of animal prey consumed. THg concentrations in waterfowl collected by hunters did not exceed consumption guidelines of 0.5 mg kg(-1) developed for fish. This is the first study that has reported MeHg concentrations in water from the prairie pothole region of southern Saskatchewan.

Research paper thumbnail of Peer Reviewed: Experimenting with Hydroelectric Reservoirs

Environmental Science & Technology, 2004

Research paper thumbnail of Long-Term Wet and Dry Deposition of Total and Methyl Mercury in the Remote Boreal Ecoregion of Canada

Environmental Science & Technology, 2008

The purpose of the METAALICUS experiment was to examine the timing and magnitude of the response ... more The purpose of the METAALICUS experiment was to examine the timing and magnitude of the response of fish Hg concentrations to changes in atmospheric Hg loading. Enriched stable Hg isotopes were applied as HgNO 3 to the lake (202 Hg), wetland (198 Hg) and upland (200 Hg) compartments of the L658 watershed at ~22 ug m-2 yr-1 since 2001 (1, 2). However, the present study focused on deposition of ambient Hg, not the experimentally-applied isotopic Hg. Analytical Methods Precipitation and throughfall samples collected between 1992 and 2000 were analysed for total Hg (THg; all forms of Hg in a sample) using EPA Method 1631 (3) by Flett Research Ltd. (Winnipeg, MB). Briefly, all Hg in samples was oxidized to Hg(II) by the addition of BrCl, reduced to Hg(0) using SnCl 2 , purged onto gold traps, thermally desorbed and analyzed by cold vapour atomic fluorescence spectrometry (CVAFS). Samples collected in the METAALICUS watershed between 2001 and 2006 were analysed using inductively coupled plasma mass spectrometry (ICP-MS, 4, 5). Because ICP-MS quantifies concentrations of individual Hg isotopes, it was possible to distinguish concentrations of ambient Hg from the experimentally loaded enriched Hg isotopes. To calculate concentrations of ambient Hg, an isotope that was not experimentally applied to the watershed was used as an ambient Hg surrogate (199 Hg). Samples collected in 2001-2004 were analyzed at the Trent University Worsfold Water Quality Center (Peterborough, ON). Samples were continuously mixed in-line with SnCl 2 using peristaltic pumps, and the reduced gaseous Hg(0) formed was separated in a custom-made gas/liquid separator and swept into the plasma of a Finnigan Element 2 ICP-MS (6). For samples collected between 2005 and 2006, analysis was completed at the University of Alberta Biogeochemical Laboratory (Edmonton, AB). In this laboratory, reduction of Hg and gas/liquid separation was accomplished using an automated Tekran 2600 total Hg analyzer interfaced with a PerkinElmer Elan DRC-e ICP-MS for detection. Precipitation and throughfall samples collected for methylmercury (MeHg) analyses prior to 2001 were distilled, ethylated by additions of sodium tetra-ethyl-borate (NaBEt 4), and volatile Hg species were purged and trapped using either carbo or tenax traps. Samples were thermally desorbed and separated by gas chromatography before quantification by CVAFS (7, 8). Samples collected in the METAALICUS watershed were analyzed for MeHg as described above, except that

Research paper thumbnail of Methylmercury and Total Mercury in Plant Litter Decomposing in Upland Forests and Flooded Landscapes

Environmental Science & Technology, 2004

Research paper thumbnail of Response | Mercury and the FLUDEX project

Environmental Science & Technology, 2005

Research paper thumbnail of Concentrations of methylmercury in invertebrates from wetlands of the Prairie Pothole Region of North America

Environmental Pollution, 2012

Prairie wetlands may be important sites of mercury (Hg) methylation resulting in elevated methylm... more Prairie wetlands may be important sites of mercury (Hg) methylation resulting in elevated methylmercury (MeHg) concentrations in water, sediments and biota. Invertebrates are an important food resource and may act as an indicator of MeHg exposure to higher organisms. In 2007e2008, invertebrates were collected from wetland ponds in central Saskatchewan, categorized into functional feeding groups (FFGs) and analyzed for total Hg (THg) and MeHg. Methylmercury and THg concentrations in four FFGs ranged from 0.2e393.5 ng$g À1 and 9.7e507.1 ng$g À1 , respectively. Methylmercury concentrations generally increased from gastropods with significantly lower average MeHg concentrations compared to other invertebrate taxa. Surrounding land use (agricultural, grassland and organic agricultural) may influence MeHg concentrations in invertebrates, with invertebrate MeHg concentrations being higher from organic ponds (457.