Mercury in the marine environment of the Canadian Arctic: Review of recent findings

• Published in: The Science of the total environment Vol. 509-510; pp. 67 - 90
• Main Authors: Braune, Birgit, Chételat, John, Amyot, Marc, Brown, Tanya, Clayden, Meredith, Evans, Marlene, Fisk, Aaron, Gaden, Ashley, Girard, Catherine, Hare, Alex, Kirk, Jane, Lehnherr, Igor, Letcher, Robert, Loseto, Lisa, Macdonald, Robie, Mann, Erin, McMeans, Bailey, Muir, Derek, O'Driscoll, Nelson, Poulain, Alexandre, Reimer, Ken, Stern, Gary
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15-03-2015
• Subjects: Arctic Regions; Bioaccumulation; Biogeochemical processes; Canada; Canadian Arctic; Environmental Monitoring; Food webs; Foods; Marine; Marine environment; Marine environments; Mercury; Mercury (metal); Mercury - analysis; Methylation; Sediments; Snow; Temporal trends; Water Pollutants, Chemical - analysis; Canada; Arctic Regions; PNW, Beaufort Sea; PN, Arctic Ocean; PNW, Canada, Hudson Bay; Marine environment; Biogeochemical processes; Temporal trends; Food webs; Mercury; Canadian Arctic
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2014.05.133

This review summarizes data and information which have been generated on mercury (Hg) in the marine environment of the Canadian Arctic since the previous Canadian Arctic Contaminants Assessment Report (CACAR) was released in 2003. Much new information has been collected on Hg concentrations in marine water, snow and ice in the Canadian Arctic. The first measurements of methylation rates in Arctic seawater indicate that the water column is an important site for Hg methylation. Arctic marine waters were also found to be a substantial source of gaseous Hg to the atmosphere during the ice-free season. High Hg concentrations have been found in marine snow as a result of deposition following atmospheric mercury depletion events, although much of this Hg is photoreduced and re-emitted back to the atmosphere. The most extensive sampling of marine sediments in the Canadian Arctic was carried out in Hudson Bay where sediment total Hg (THg) concentrations were low compared with other marine regions in the circumpolar Arctic. Mass balance models have been developed to provide quantitative estimates of THg fluxes into and out of the Arctic Ocean and Hudson Bay.
Several recent studies on Hg biomagnification have improved our understanding of trophic transfer of Hg through marine food webs. Over the past several decades, Hg concentrations have increased in some marine biota, while other populations showed no temporal change. Marine biota also exhibited considerable geographic variation in Hg concentrations with ringed seals, beluga and polar bears from the Beaufort Sea region having higher Hg concentrations compared with other parts of the Canadian Arctic. The drivers of these variable patterns of Hg bioaccumulation, both regionally and temporally, within the Canadian Arctic remain unclear. Further research is needed to identify the underlying processes including the interplay between biogeochemical and food web processes and climate change.
•The water column in Arctic marine waters is important for mercury methylation.•Mercury deposited on marine snow pack is rapidly re-emitted to the atmosphere.•Rates of mercury biomagnification were similar across Arctic marine food webs.•Mercury is higher in Beaufort Sea biota than in other Canadian Arctic areas.•Mercury in some marine biota has increased in recent decades.