Methylmercury in Seawater and Its Bioaccumulation in Marine Food Webs of the Canadian Arctic
Mercury (Hg) is a major contaminant in the Arctic marine ecosystem, with concentrations in marine mammals and Indigenous Peoples frequently exceeding safety thresholds. The key step of Hg bioaccumulation is Hg methylation in the ocean, as the resulting monomethylmercury (MMHg) biomagnifies in the ma...
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Online Access: | http://hdl.handle.net/1993/33838 |
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ftunivmanitoba:oai:mspace.lib.umanitoba.ca:1993/33838 2023-06-18T03:38:28+02:00 Methylmercury in Seawater and Its Bioaccumulation in Marine Food Webs of the Canadian Arctic Wang, Kang Wang, Feiyue (Environment and Geography) Stern, Gary (Environment and Geography) Macdonald, Robbie (Environment and Geography) Kuzyk, Zou Zou (Geological Sciences) Letcher, Robert (Chemistry, Carleton University) 2019-03-28T18:31:34Z application/pdf http://hdl.handle.net/1993/33838 eng eng Wang, K., Munson, K.M., Beaupré-Laperrière, A., Mucci, A., Macdonald, R.M., Wang, F. (2018). Subsurface seawater methylmercury maximum explains biotic mercury concentrations in the Canadian Arctic. Scientific Reports, 8(1), 14465. https://doi.org/10.1038/s41598-018-32760-0. http://hdl.handle.net/1993/33838 open access Methylmercury Seawater Canadian Arctic Bioaccumulation doctoral thesis 2019 ftunivmanitoba https://doi.org/10.1038/s41598-018-32760-0 2023-06-04T17:39:19Z Mercury (Hg) is a major contaminant in the Arctic marine ecosystem, with concentrations in marine mammals and Indigenous Peoples frequently exceeding safety thresholds. The key step of Hg bioaccumulation is Hg methylation in the ocean, as the resulting monomethylmercury (MMHg) biomagnifies in the marine food webs. However, little is known about the sources and dynamics of seawater MMHg in the Arctic. In this research, high vertical resolution profiles of total Hg and methylated Hg (MeHg, sum of MMHg and dimethylmercury) were measured, for the first time, in seawater across the Canadian Arctic from the Canada Basin in the west, through the Canadian Arctic Archipelago, to Baffin Bay in the east and reaching Labrador Sea in the North Atlantic Ocean. Whereas total Hg concentrations are lower in the western Canadian Arctic, MeHg is enriched at shallow depths and its peak concentration decreases from west to east. Biological uptake of this subsurface MeHg and subsequent biomagnification can readily explain the regional gradients of biotic Hg in the Canadian Arctic. Seawater MeHg concentrations show significant correlations with nutrients and apparent oxygen utilization, but this does not necessarily support that MeHg is produced in-situ in the water column; instead, further analysis with water masses and N* reveals that the subsurface MeHg is likely originated from the Chukchi Sea sediments and advected within the Upper Halocline Water to the Canadian Arctic. The long-distance transport implies that MeHg in Arctic seawater must have a half-life much longer than previously determined from the seawater incubation approach, which is problematic in estimating Hg methylation and demethylation rates in seawater. Incubation studies with an Arctic copepod (Calanus hyperboreus) show that the microenvironments in copepod guts and fecal pellets are unlikely hotspots for Hg methylation, and that the copepod preferentially bioaccumulates MMHg over inorganic Hg and the main uptake pathway is trophic transfer. This study underlines ... Doctoral or Postdoctoral Thesis Arctic Arctic Archipelago Arctic copepod Arctic Baffin Bay Baffin Bay Baffin Calanus hyperboreus canada basin Canadian Arctic Archipelago Chukchi Chukchi Sea Labrador Sea North Atlantic MSpace at the University of Manitoba Arctic Baffin Bay Canada Canadian Arctic Archipelago Chukchi Sea Scientific Reports 8 1 |
institution |
Open Polar |
collection |
MSpace at the University of Manitoba |
op_collection_id |
ftunivmanitoba |
language |
English |
topic |
Methylmercury Seawater Canadian Arctic Bioaccumulation |
spellingShingle |
Methylmercury Seawater Canadian Arctic Bioaccumulation Wang, Kang Methylmercury in Seawater and Its Bioaccumulation in Marine Food Webs of the Canadian Arctic |
topic_facet |
Methylmercury Seawater Canadian Arctic Bioaccumulation |
description |
Mercury (Hg) is a major contaminant in the Arctic marine ecosystem, with concentrations in marine mammals and Indigenous Peoples frequently exceeding safety thresholds. The key step of Hg bioaccumulation is Hg methylation in the ocean, as the resulting monomethylmercury (MMHg) biomagnifies in the marine food webs. However, little is known about the sources and dynamics of seawater MMHg in the Arctic. In this research, high vertical resolution profiles of total Hg and methylated Hg (MeHg, sum of MMHg and dimethylmercury) were measured, for the first time, in seawater across the Canadian Arctic from the Canada Basin in the west, through the Canadian Arctic Archipelago, to Baffin Bay in the east and reaching Labrador Sea in the North Atlantic Ocean. Whereas total Hg concentrations are lower in the western Canadian Arctic, MeHg is enriched at shallow depths and its peak concentration decreases from west to east. Biological uptake of this subsurface MeHg and subsequent biomagnification can readily explain the regional gradients of biotic Hg in the Canadian Arctic. Seawater MeHg concentrations show significant correlations with nutrients and apparent oxygen utilization, but this does not necessarily support that MeHg is produced in-situ in the water column; instead, further analysis with water masses and N* reveals that the subsurface MeHg is likely originated from the Chukchi Sea sediments and advected within the Upper Halocline Water to the Canadian Arctic. The long-distance transport implies that MeHg in Arctic seawater must have a half-life much longer than previously determined from the seawater incubation approach, which is problematic in estimating Hg methylation and demethylation rates in seawater. Incubation studies with an Arctic copepod (Calanus hyperboreus) show that the microenvironments in copepod guts and fecal pellets are unlikely hotspots for Hg methylation, and that the copepod preferentially bioaccumulates MMHg over inorganic Hg and the main uptake pathway is trophic transfer. This study underlines ... |
author2 |
Wang, Feiyue (Environment and Geography) Stern, Gary (Environment and Geography) Macdonald, Robbie (Environment and Geography) Kuzyk, Zou Zou (Geological Sciences) Letcher, Robert (Chemistry, Carleton University) |
format |
Doctoral or Postdoctoral Thesis |
author |
Wang, Kang |
author_facet |
Wang, Kang |
author_sort |
Wang, Kang |
title |
Methylmercury in Seawater and Its Bioaccumulation in Marine Food Webs of the Canadian Arctic |
title_short |
Methylmercury in Seawater and Its Bioaccumulation in Marine Food Webs of the Canadian Arctic |
title_full |
Methylmercury in Seawater and Its Bioaccumulation in Marine Food Webs of the Canadian Arctic |
title_fullStr |
Methylmercury in Seawater and Its Bioaccumulation in Marine Food Webs of the Canadian Arctic |
title_full_unstemmed |
Methylmercury in Seawater and Its Bioaccumulation in Marine Food Webs of the Canadian Arctic |
title_sort |
methylmercury in seawater and its bioaccumulation in marine food webs of the canadian arctic |
publishDate |
2019 |
url |
http://hdl.handle.net/1993/33838 |
geographic |
Arctic Baffin Bay Canada Canadian Arctic Archipelago Chukchi Sea |
geographic_facet |
Arctic Baffin Bay Canada Canadian Arctic Archipelago Chukchi Sea |
genre |
Arctic Arctic Archipelago Arctic copepod Arctic Baffin Bay Baffin Bay Baffin Calanus hyperboreus canada basin Canadian Arctic Archipelago Chukchi Chukchi Sea Labrador Sea North Atlantic |
genre_facet |
Arctic Arctic Archipelago Arctic copepod Arctic Baffin Bay Baffin Bay Baffin Calanus hyperboreus canada basin Canadian Arctic Archipelago Chukchi Chukchi Sea Labrador Sea North Atlantic |
op_relation |
Wang, K., Munson, K.M., Beaupré-Laperrière, A., Mucci, A., Macdonald, R.M., Wang, F. (2018). Subsurface seawater methylmercury maximum explains biotic mercury concentrations in the Canadian Arctic. Scientific Reports, 8(1), 14465. https://doi.org/10.1038/s41598-018-32760-0. http://hdl.handle.net/1993/33838 |
op_rights |
open access |
op_doi |
https://doi.org/10.1038/s41598-018-32760-0 |
container_title |
Scientific Reports |
container_volume |
8 |
container_issue |
1 |
_version_ |
1769003471529312256 |