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Atmospheric Concentrations and Wet/Dry Loadings of Mercury at the Remote Experimental Lakes Area, Northwestern Ontario, Canada.

https://arctichealth.org/en/permalink/ahliterature301563
Source
Environ Sci Technol. 2019 Jul 16; 53(14):8017-8026
Publication Type
Journal Article
Date
Jul-16-2019
Author
Vincent L St Louis
Jennifer A Graydon
Igor Lehnherr
Helen M Amos
Elsie M Sunderland
Kyra A St Pierre
Craig A Emmerton
Ken Sandilands
Michael Tate
Alexandra Steffen
Elyn R Humphreys
Author Affiliation
Department of Biological Sciences , University of Alberta , Edmonton , Alberta T6G 2E9 , Canada.
Source
Environ Sci Technol. 2019 Jul 16; 53(14):8017-8026
Date
Jul-16-2019
Language
English
Publication Type
Journal Article
Abstract
Mercury (Hg) is a global pollutant released from both natural and human sources. Here we compare long-term records of wet deposition loadings of total Hg (THg) in the open to dry deposition loadings of THg in throughfall and litterfall under four boreal mixedwood canopy types at the remote Experimental Lakes Area (ELA) in Northwestern Ontario, Canada. We also present long-term records of atmospheric concentrations of gaseous elemental (GEM), gaseous oxidized (GOM), and particle bound (PBM) Hg measured at the ELA. We show that dry THg loadings in throughfall and litterfall are 2.7 to 6.1 times greater than wet THg loadings in the open. GEM concentrations showed distinct monthly and daily patterns, correlating positively in spring and summer with rates of gross ecosystem productivity and respiration. GOM and PBM concentrations were less variable throughout the year but were highest in the winter, when concentrations of anthropogenically sourced particles and gases were also high. Forest fires, Arctic air masses, and road salt also impacted GEM, GOM, and PBM concentrations at the ELA. A nested GEOS-Chem simulation for the ELA region produced a dry/wet deposition ratio of >5, suggesting that the importance of dry deposition in forested regions can be reasonably modeled by existing schemes for trace gases.
PubMed ID
31250626 View in PubMed
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Contrasting the ecological effects of decreasing ice cover versus accelerated glacial melt on the High Arctic's largest lake.

https://arctichealth.org/en/permalink/ahliterature305488
Source
Proc Biol Sci. 2020 06 24; 287(1929):20201185
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Date
06-24-2020
Author
Neal Michelutti
Marianne S V Douglas
Dermot Antoniades
Igor Lehnherr
Vincent L St Louis
Kyra St Pierre
Derek C G Muir
Gregg Brunskill
John P Smol
Author Affiliation
Paleoecological Environmental Assessment and Research Laboratory (PEARL), Department of Biology, Queen's University, Kingston, Ontario, Canada K7L 3N6.
Source
Proc Biol Sci. 2020 06 24; 287(1929):20201185
Date
06-24-2020
Language
English
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Keywords
Arctic Regions
Climate change
Diatoms
Ecosystem
Environmental monitoring
Ice Cover
Lakes
Plankton
Abstract
Lake Hazen, the High Arctic's largest lake, has received an approximately 10-fold increase in glacial meltwater since its catchment glaciers shifted from net mass gain to net mass loss in 2007 common era (CE), concurrent with recent warming. Increased glacial meltwater can alter the ecological functioning of recipient aquatic ecosystems via changes to nutrient budgets, turbidity and thermal regimes. Here, we examine a rare set of five high-resolution sediment cores collected in Lake Hazen between 1990 and 2017 CE to investigate the influence of increased glacial meltwater versus alterations to lake ice phenology on ecological change. Subfossil diatom assemblages in all cores show two major shifts over the past approximately 200 years including: (i) a proliferation of pioneering, benthic taxa at approximately 1900 CE from previously depauperate populations; and (ii) a rise in planktonic taxa beginning at approximately 1980 CE to present-day dominance. The topmost intervals from each sequentially collected core provide exact dates and demonstrate that diatom regime shifts occurred decades prior to accelerated glacial inputs. These data show that diatom assemblages in Lake Hazen are responding primarily to intrinsic lake factors linked to decreasing duration of lake ice and snow cover rather than to limnological impacts associated with increased glacial runoff.
PubMed ID
32576110 View in PubMed
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Determination of monomethylmercury and dimethylmercury in the Arctic marine boundary layer.

https://arctichealth.org/en/permalink/ahliterature258474
Source
Environ Sci Technol. 2014 Dec 1;
Publication Type
Article
Date
Dec-1-2014
Author
Pascale A Baya
Michel Gosselin
Igor Lehnherr
Vincent L St Louis
Holger Hintelmann
Source
Environ Sci Technol. 2014 Dec 1;
Date
Dec-1-2014
Language
English
Publication Type
Article
Abstract
Our understanding of the biogeochemical cycling of monomethylmercury (MMHg) in the Arctic is incomplete because atmospheric sources and sinks of MMHg are still unclear. We sampled air in the Canadian Arctic marine boundary layer to quantify, for the first time, atmospheric concentrations of methylated Hg species (both MMHg and dimethylmercury (DMHg)), and, estimate the importance of atmospheric deposition as a source of MMHg to Arctic land- and sea-scapes. Overall atmospheric MMHg and DMHg concentrations (mean ± SD) were 2.9 ± 3.6 and 3.8 ± 3.1 pg m-3, respectively. Concentrations of methylated Hg species in the marine boundary layer significantly varied amongst our sites, with a predominance of MMHg over Hudson Bay (HB), and DMHg over Canadian Arctic Archipelago (CAA) waters. We concluded that DMHg is of marine origin and that primary production rate and sea-ice cover are major drivers of its concentration in the Canadian Arctic marine boundary layer. Summer wet deposition rates of atmospheric MMHg, likely to be the product of DMHg degradation in the atmosphere, were estimated at 188 ± 117.5 ng m-2 and 37 ± 21.7 ng m-2 for HB and CAA, respectively, sustaining MMHg concentrations available for bio-magnification in the pelagic food web.
PubMed ID
25437177 View in PubMed
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Differences in Mercury Bioaccumulation between Polar Bears (Ursus maritimus) from the Canadian high- and sub-Arctic.

https://arctichealth.org/en/permalink/ahliterature100877
Source
Environ Sci Technol. 2011 Jun 16;
Publication Type
Article
Date
Jun-16-2011
Author
Vincent L St Louis
Andrew E Derocher
Ian Stirling
Jennifer A Graydon
Caroline Lee
Erin Jocksch
Evan Richardson
Sarah Ghorpade
Alvin K Kwan
Jane L Kirk
Igor Lehnherr
Heidi K Swanson
Author Affiliation
Department of Biological Sciences, University of Alberta , Edmonton, Alberta Canada T6G 2E9.
Source
Environ Sci Technol. 2011 Jun 16;
Date
Jun-16-2011
Language
English
Publication Type
Article
Abstract
Polar bears (Ursus maritimus) are being impacted by climate change and increased exposure to pollutants throughout their northern circumpolar range. In this study, we quantified concentrations of total mercury (THg) in the hair of polar bears from Canadian high- (southern Beaufort Sea, SBS) and sub- (western Hudson Bay, WHB) Arctic populations. Concentrations of THg in polar bears from the SBS population (14.8 ± 6.6 µg g(-1)) were significantly higher than in polar bears from WHB (4.1 ± 1.0 µg g(-1)). On the basis of d(15)N signatures in hair, in conjunction with published d(15)N signatures in particulate organic matter and sediments, we estimated that the pelagic and benthic food webs in the SBS are ~4.7 and ~4.0 trophic levels long, whereas in WHB they are only ~3.6 and ~3.3 trophic levels long. Furthermore, the more depleted d(13)C ratios in hair from SBS polar bears relative to those from WHB suggests that SBS polar bears feed on food webs that are relatively more pelagic (and longer), whereas polar bears from WHB feed on those that are relatively more benthic (and shorter). Food web length and structure accounted for ~67% of the variation we found in THg concentrations among all polar bears across both populations. The regional difference in polar bear hair THg concentrations was also likely due to regional differences in water-column concentrations of methyl Hg (the toxic form of Hg that biomagnifies through food webs) available for bioaccumulation at the base of the food webs. For example, concentrations of methylated Hg at mid-depths in the marine water column of the northern Canadian Arctic Archipelago were 79.8 ± 37.3 pg L(-1), whereas, in HB, they averaged only 38.3 ± 16.6 pg L(-1). We conclude that a longer food web and higher pelagic concentrations of methylated Hg available to initiate bioaccumulation in the BS resulted in higher concentrations of THg in polar bears from the SBS region compared to those inhabiting the western coast of HB.
PubMed ID
21678897 View in PubMed
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Fate and Transport of Perfluoroalkyl Substances from Snowpacks into a Lake in the High Arctic of Canada.

https://arctichealth.org/en/permalink/ahliterature310082
Source
Environ Sci Technol. 2019 Sep 17; 53(18):10753-10762
Publication Type
Journal Article
Date
Sep-17-2019
Author
John J MacInnis
Igor Lehnherr
Derek C G Muir
Kyra A St Pierre
Vincent L St Louis
Christine Spencer
Amila O De Silva
Author Affiliation
Department of Chemistry , Memorial University , St. John's , Newfoundland and Labrador A1B 3X7 , Canada.
Source
Environ Sci Technol. 2019 Sep 17; 53(18):10753-10762
Date
Sep-17-2019
Language
English
Publication Type
Journal Article
Keywords
Arctic Regions
Canada
Environmental monitoring
Fluorocarbons
Lakes
Nunavut
Abstract
The delivery of perfluoroalkyl substances (PFAS) from snowpacks into Lake Hazen, located on Ellesmere Island (Nunavut, Canada, 82° N) indicates that annual atmospheric deposition is a major source of PFAS that undergo complex cycling in the High Arctic. Perfluoroalkyl carboxylic acids (PFCA) in snowpacks display odd-even concentration ratios characteristic of long-range atmospheric transport and oxidation of volatile precursors. Major ion analysis in snowpacks suggests that sea spray, mineral dust, and combustion aerosol are all relevant to the fate of PFAS in the Lake Hazen watershed. Distinct drifts of light and dark snow (enriched with light absorbing particles, LAPs) facilitate the study of particle loads on the fate of PFAS in the snowpack. Total PFAS (SPFAS, ng m-2) loads are lower in snowpacks enriched with LAPs and are attributed to reductions in snowpack albedo combined with enhanced post-depositional melting. Elevated concentrations of PFCA are observed in the top 5 m of the water column during snowmelt periods compared to ice-covered or ice-free periods. PFAS concentrations in deep waters of the Lake Hazen water column were consistent between snowmelt, ice-free, and ice-covered periods, which is ascribed to the delivery of dense and turbid glacier meltwaters mixing PFAS throughout the Lake Hazen water column. These observations highlight the underlying mechanisms in PFAS cycling in High Arctic Lakes particularly in the context of increased particle loads and melting.
PubMed ID
31412696 View in PubMed
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Hair Mercury Concentrations in Western Hudson Bay Polar Bear Family Groups.

https://arctichealth.org/en/permalink/ahliterature271914
Source
Environ Sci Technol. 2016 Apr 29;
Publication Type
Article
Date
Apr-29-2016
Author
Thea Bechshoft
Andrew E Derocher
Evan Richardson
Nicholas J Lunn
Vincent L St Louis
Source
Environ Sci Technol. 2016 Apr 29;
Date
Apr-29-2016
Language
English
Publication Type
Article
Abstract
Methylmercury is one of the more toxic forms of mercury (Hg), the biomagnification of which is prevalent in the Arctic where apex predators such as polar bears (Ursus maritimus) can carry high loads. The maternal transfer of contaminants to offspring is a concern, as offspring may be particularly sensitive to the effects of environmental pollutants during early development. However, few studies of polar bears report on Hg in dependent young. We examined hair total Hg (THg) concentrations in 24 polar bear family groups in western Hudson Bay: mother, cub-of-the-year (COY), yearling, and 2 year old. THg concentrations increased with bear age, with COYs having lower concentrations than other offspring groups (p = 0.008). Using AICc-based regression models, we found maternal THg to be positively related to body condition and litter size, while overall offspring THg was positively related to maternal body condition in addition to being dependent on the sex and age of the offspring. COY THg concentrations were positively related to maternal THg while also depending on the sex of the offspring. Considering our results, future studies in polar bear ecotoxicology are encouraged to include offspring of different ages and sexes.
PubMed ID
27095340 View in PubMed
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Long-term wet and dry deposition of total and methyl mercury in the remote boreal ecoregion of Canada.

https://arctichealth.org/en/permalink/ahliterature153788
Source
Environ Sci Technol. 2008 Nov 15;42(22):8345-51
Publication Type
Article
Date
Nov-15-2008
Author
Jennifer A Graydon
Vincent L St Louis
Holger Hintelmann
Steve E Lindberg
Ken A Sandilands
John W M Rudd
Carol A Kelly
Britt D Hall
Linnea D Mowat
Author Affiliation
Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2E9. jgraydon@ualberta.ca
Source
Environ Sci Technol. 2008 Nov 15;42(22):8345-51
Date
Nov-15-2008
Language
English
Publication Type
Article
Keywords
Animals
Ecosystem
Environmental Monitoring - methods
Fresh Water
Humans
Methylmercury compounds - analysis
Ontario
Trees
Water Pollutants, Chemical - analysis
Wetlands
Abstract
Although a positive relationship between atmospheric loadings of inorganic mercury (Hg(II)) to watersheds and concentrations of methyl mercury (MeHg) in fish has now been established, net wet and dry deposition of Hg(II) and MeHg to watersheds remains challenging to quantify. In this study, concentrations and loadings of total mercury (THg; all forms of Hg in a sample) and MeHg in open area wet deposition, throughfall, and litterfall were quantified atthe remote Experimental Lakes Area in the boreal ecoregion, NW Ontario, Canada. Between 1992 and 2006, mean annual THg and MeHg loadings in the open were 36 +/- 17 and 0.5 +/- 0.2 mg ha(-1), respectively. Throughfall THg and MeHg loadings were generally 2-4 times and 0.8-2 times higher, respectively, than loadings in the open. Loadings of both THg and MeHg were highest under an old growth spruce/fir canopy and lowest under a deciduous maple canopy, whereas loadings under young jack pine and wetland spruce/pine/alder canopies were intermediate. Litterfall generally represented the largest input of THg (86-105 mg ha(-1)) and MeHg (0.7-0.8 mg ha(-1)) to the landscape on an annual basis. Using the "direct" method of estimating dry deposition (thoughfall + litterfall - open loadings), we calculated that annual dry deposition of THg and MeHg under forest canopies ranged from 105 to 201 mg ha(-1), whereas dry deposition of MeHg ranged from 0.7 to 1.2 mg ha(-1). Photoreduction and emission of wet-deposited Hg(ll) from canopy foliage were accounted for, resulting in 3-5% (5-6 mg ha(-1)) higher annual estimates of dry deposition than via the direct method alone. NetTHg and MeHg loadings to this remote landscape were lower than at any other previously studied forested site globally. This study shows that THg and MeHg loading can be extremely variable within a heterogeneous boreal landscape and that processes such as Hg photoreduction and emission from foliage should be considered when estimating dry deposition of Hg.
PubMed ID
19068816 View in PubMed
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Mercury in Arctic marine ecosystems: sources, pathways and exposure.

https://arctichealth.org/en/permalink/ahliterature119433
Source
Environ Res. 2012 Nov;119:64-87
Publication Type
Article
Date
Nov-2012
Author
Jane L Kirk
Igor Lehnherr
Maria Andersson
Birgit M Braune
Laurie Chan
Ashu P Dastoor
Dorothy Durnford
Amber L Gleason
Lisa L Loseto
Alexandra Steffen
Vincent L St Louis
Author Affiliation
Environment Canada, Aquatic Contaminants Research Division, 867 Lakeshore Dr, Burlington, ON L7R 4A6, Canada. Jane.Kirk@ec.gc.ca
Source
Environ Res. 2012 Nov;119:64-87
Date
Nov-2012
Language
English
Publication Type
Article
Keywords
Animals
Arctic Regions
Ecosystem
Environmental Exposure
Humans
Mercury - chemistry - metabolism
Water Pollutants, Chemical - chemistry - metabolism
Abstract
Mercury in the Arctic is an important environmental and human health issue. The reliance of Northern Peoples on traditional foods, such as marine mammals, for subsistence means that they are particularly at risk from mercury exposure. The cycling of mercury in Arctic marine systems is reviewed here, with emphasis placed on the key sources, pathways and processes which regulate mercury levels in marine food webs and ultimately the exposure of human populations to this contaminant. While many knowledge gaps exist limiting our ability to make strong conclusions, it appears that the long-range transport of mercury from Asian emissions is an important source of atmospheric Hg to the Arctic and that mercury methylation resulting in monomethylmercury production (an organic form of mercury which is both toxic and bioaccumulated) in Arctic marine waters is the principal source of mercury incorporated into food webs. Mercury concentrations in biological organisms have increased since the onset of the industrial age and are controlled by a combination of abiotic factors (e.g., monomethylmercury supply), food web dynamics and structure, and animal behavior (e.g., habitat selection and feeding behavior). Finally, although some Northern Peoples have high mercury concentrations of mercury in their blood and hair, harvesting and consuming traditional foods have many nutritional, social, cultural and physical health benefits which must be considered in risk management and communication.
Notes
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PubMed ID
23102902 View in PubMed
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Net ecosystem exchange of CO2 with rapidly changing high Arctic landscapes.

https://arctichealth.org/en/permalink/ahliterature265526
Source
Glob Chang Biol. 2015 Aug 17;
Publication Type
Article
Date
Aug-17-2015
Author
Craig A Emmerton
Vincent L St Louis
Elyn R Humphreys
John A Gamon
Joel D Barker
Gilberto Z Pastorello
Source
Glob Chang Biol. 2015 Aug 17;
Date
Aug-17-2015
Language
English
Publication Type
Article
Abstract
High Arctic landscapes are expansive and changing rapidly. However our understanding of their functional responses and potential to mitigate or enhance anthropogenic climate change is limited by few measurements. We collected eddy covariance measurements to quantify the net ecosystem exchange (NEE) of CO2 with polar semidesert and meadow wetland landscapes at the highest-latitude location measured to date (82°N). We coupled these rare data with ground and satellite vegetation production measurements (Normalized Difference Vegetation Index; NDVI) to evaluate the effectiveness of upscaling local to regional NEE. During the growing season, the dry polar semidesert landscape was a near zero sink of atmospheric CO2 (NEE: -0.3±13.5 g C m(-2) ). A nearby meadow wetland accumulated over 300 times more carbon (NEE: -79.3±20.0 g C m(-2) ) than the polar semidesert landscape, and was similar to meadow wetland NEE at much more southerly latitudes. Polar semidesert NEE was most influenced by moisture, with wetter surface soils resulting in greater soil respiration and CO2 emissions. At the meadow wetland, soil heating enhanced plant growth, which in turn increased CO2 uptake. Our upscaling assessment found that polar semidesert NDVI measured on site was low (mean: 0.120-0.157) and similar to satellite measurements (mean: 0.155-0.163). However, weak plant growth resulted in poor satellite NDVI-NEE relationships and created challenges for remotely-detecting changes in the cycling of carbon on the polar semidesert landscape. The meadow wetland appeared more suitable to assess plant production and NEE via remote-sensing, however high Arctic wetland extent is constrained by topography to small areas that may be difficult to resolve with large satellite pixels. We predict that until summer precipitation and humidity increases substantially, climate-related changes of dry high Arctic landscapes may be restricted by poor soil moisture retention, and therefore have some inertia against short-term changes in NEE. This article is protected by copyright. All rights reserved.
PubMed ID
26279166 View in PubMed
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Physicochemical Drivers of Microbial Community Structure in Sediments of Lake Hazen, Nunavut, Canada.

https://arctichealth.org/en/permalink/ahliterature292428
Source
Front Microbiol. 2018; 9:1138
Publication Type
Journal Article
Date
2018
Author
Matti O Ruuskanen
Kyra A St Pierre
Vincent L St Louis
Stéphane Aris-Brosou
Alexandre J Poulain
Author Affiliation
Department of Biology, University of Ottawa, Ottawa, ON, Canada.
Source
Front Microbiol. 2018; 9:1138
Date
2018
Language
English
Publication Type
Journal Article
Abstract
The Arctic is undergoing rapid environmental change, potentially affecting the physicochemical constraints of microbial communities that play a large role in both carbon and nutrient cycling in lacustrine environments. However, the microbial communities in such Arctic environments have seldom been studied, and the drivers of their composition are poorly characterized. To address these gaps, we surveyed the biologically active surface sediments in Lake Hazen, the largest lake by volume north of the Arctic Circle, and a small lake and shoreline pond in its watershed. High-throughput amplicon sequencing of the 16S rRNA gene uncovered a community dominated by Proteobacteria, Bacteroidetes, and Chloroflexi, similar to those found in other cold and oligotrophic lake sediments. We also show that the microbial community structure in this Arctic polar desert is shaped by pH and redox gradients. This study lays the groundwork for predicting how sediment microbial communities in the Arctic could respond as climate change proceeds to alter their physicochemical constraints.
Notes
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