title: Mercury in freshwater ecosystems of the Canadian Arctic: recent advances on its cycling and fate.
abstract: The Canadian Arctic has vast freshwater resources, and fish are important in the diet of many Northerners. Mercury is a contaminant of concern because of its potential toxicity and elevated bioaccumulation in some fish populations. Over the last decade, significant advances have been made in characterizing the cycling and fate of mercury in these freshwater environments. Large amounts of new data on concentrations, speciation and fluxes of Hg are provided and summarized for water and sediment, which were virtually absent for the Canadian Arctic a decade ago. The biogeochemical processes that control the speciation of mercury remain poorly resolved, including the sites and controls of methylmercury production. Food web studies have examined the roles of Hg uptake, trophic transfer, and diet for Hg bioaccumulation in fish, and, in particular, advances have been made in identifying determinants of mercury levels in lake-dwelling and sea-run forms of Arctic char. In a comparison of common freshwater fish species that were sampled across the Canadian Arctic between 2002 and 2009, no geographic patterns or regional hotspots were evident. Over the last two to four decades, Hg concentrations have increased in some monitored populations of fish in the Mackenzie River Basin while other populations from the Yukon and Nunavut showed no change or a slight decline. The different Hg trends indicate that the drivers of temporal change may be regional or habitat-specific. The Canadian Arctic is undergoing profound environmental change, and preliminary evidence suggests that it may be impacting the cycling and bioaccumulation of mercury. Further research is needed to investigate climate change impacts on the Hg cycle as well as biogeochemical controls of methylmercury production and the processes leading to increasing Hg levels in some fish populations in the Canadian Arctic.
authors.affiliation: Environment Canada, National Wildlife Research Centre, Ottawa, Ontario K1A 0H3, Canada. Electronic address: John.Chetelat@ec.gc.ca.
authors.forename: John
authors.initials: J
authors.lastname: Chételat
authors.affiliation: Centre d'études nordiques, Département de sciences biologiques, Université de Montréal, Montreal, Quebec H3C 3J7, Canada.
authors.forename: Marc
authors.initials: M
authors.lastname: Amyot
authors.affiliation: Faculty of Forestry and Environmental Management, University of New Brunswick, Fredericton, New Brunswick E3B 5A3, Canada.
authors.forename: Paul
authors.initials: P
authors.lastname: Arp
authors.affiliation: Department of Biology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada.
authors.forename: Jules M
authors.initials: JM
authors.lastname: Blais
authors.affiliation: Environment Canada, Canada Centre for Inland Waters, Burlington, Ontario L7R 4A6, Canada.
authors.forename: David
authors.initials: D
authors.lastname: Depew
authors.affiliation: Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada.
authors.forename: Craig A
authors.initials: CA
authors.lastname: Emmerton
authors.affiliation: Environment Canada, Aquatic Contaminants Research Division, Saskatoon, Saskatchewan S7N 3H5, Canada.
authors.forename: Marlene
authors.initials: M
authors.lastname: Evans
authors.affiliation: Gamberg Consulting, Whitehorse, Yukon Y1A 5M2, Canada.
authors.forename: Mary
authors.initials: M
authors.lastname: Gamberg
authors.affiliation: Department of Geography, University of Victoria, Victoria, BC V8W 3R4, Canada.
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Gantner
authors.affiliation: Centre d'études nordiques, Département de sciences biologiques, Université de Montréal, Montreal, Quebec H3C 3J7, Canada.
authors.forename: Catherine
authors.initials: C
authors.lastname: Girard
authors.affiliation: Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Graydon
authors.affiliation: Environment Canada, Canada Centre for Inland Waters, Burlington, Ontario L7R 4A6, Canada.
authors.forename: Jane
authors.initials: J
authors.lastname: Kirk
authors.affiliation: Lean Environmental, Apsley, Ontario K0L 1A0, Canada.
authors.forename: David
authors.initials: D
authors.lastname: Lean
authors.affiliation: Earth and Environmental Sciences, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
authors.forename: Igor
authors.initials: I
authors.lastname: Lehnherr
authors.affiliation: Environment Canada, Canada Centre for Inland Waters, Burlington, Ontario L7R 4A6, Canada.
authors.forename: Derek
authors.initials: D
authors.lastname: Muir
authors.affiliation: Faculty of Forestry and Environmental Management, University of New Brunswick, Fredericton, New Brunswick E3B 5A3, Canada.
authors.forename: Mina
authors.initials: M
authors.lastname: Nasr
authors.affiliation: Department of Biology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada.
authors.forename: Alexandre J
authors.initials: AJ
authors.lastname: Poulain
authors.affiliation: Department of Biology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
authors.forename: Michael
authors.initials: M
authors.lastname: Power
authors.affiliation: Aboriginal Affairs and Northern Development Canada, Whitehorse, Yukon Y1A 2B5, Canada.
authors.forename: Pat
authors.initials: P
authors.lastname: Roach
authors.affiliation: Centre for Earth Observation Science, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada.
authors.forename: Gary
authors.initials: G
authors.lastname: Stern
authors.affiliation: Department of Biology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
authors.forename: Heidi
authors.initials: H
authors.lastname: Swanson
authors.affiliation: Department of Biology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
authors.forename: Shannon
authors.initials: S
authors.lastname: van der Velden
mesh_terms: D000818:Animals; D001110:Arctic Regions; D002170:Canada; D017753:Ecosystem; D004784:Environmental Monitoring; D020387:Food Chain; D008628:Mercury / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D014874:Water Pollutants, Chemical; D008628:Mercury
keywords: Arctic; Bioaccumulation; Biogeochemistry; Fresh water; Mercury; Temporal trends