High Methylmercury in Arctic and Subarctic Ponds is Related to Nutrient Levels in the Warming Eastern Canadian Arctic

Permafrost thaw ponds are ubiquitous in the eastern Canadian Arctic, yet little information exists on their potential as sources of methylmercury (MeHg) to freshwaters. They are microbially active and conducive to methylation of inorganic mercury, and are also affected by Arctic warming. This multiy...

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Veröffentlicht in:Environmental science & technology Jg. 49; H. 13; S. 7743
Hauptverfasser: MacMillan, Gwyneth A, Girard, Catherine, Chételat, John, Laurion, Isabelle, Amyot, Marc
Format: Journal Article
Sprache:Englisch
Veröffentlicht: United States 07.07.2015
Schlagworte:
Arctic Regions
Canada
Carbon Dioxide - analysis
Ecosystem
Environmental Monitoring
Global Warming
Lakes - analysis
Mercury - analysis
Methane - analysis
Methylmercury Compounds - analysis
Nitrogen - analysis
Nunavut
Phosphorus - analysis
Ponds - analysis
Ponds - chemistry
Water Pollutants, Chemical - analysis
ISSN:1520-5851, 1520-5851
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Zusammenfassung:Permafrost thaw ponds are ubiquitous in the eastern Canadian Arctic, yet little information exists on their potential as sources of methylmercury (MeHg) to freshwaters. They are microbially active and conducive to methylation of inorganic mercury, and are also affected by Arctic warming. This multiyear study investigated thaw ponds in a discontinuous permafrost region in the Subarctic taiga (Kuujjuarapik-Whapmagoostui, QC) and a continuous permafrost region in the Arctic tundra (Bylot Island, NU). MeHg concentrations in thaw ponds were well above levels measured in most freshwater ecosystems in the Canadian Arctic (>0.1 ng L(-1)). On Bylot, ice-wedge trough ponds showed significantly higher MeHg (0.3-2.2 ng L(-1)) than polygonal ponds (0.1-0.3 ng L(-1)) or lakes (<0.1 ng L(-1)). High MeHg was measured in the bottom waters of Subarctic thaw ponds near Kuujjuarapik (0.1-3.1 ng L(-1)). High water MeHg concentrations in thaw ponds were strongly correlated with variables associated with high inputs of organic matter (DOC, a320, Fe), nutrients (TP, TN), and microbial activity (dissolved CO2 and CH4). Thawing permafrost due to Arctic warming will continue to release nutrients and organic carbon into these systems and increase ponding in some regions, likely stimulating higher water concentrations of MeHg. Greater hydrological connectivity from permafrost thawing may potentially increase transport of MeHg from thaw ponds to neighboring aquatic ecosystems.
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ISSN:1520-5851
1520-5851
DOI:10.1021/acs.est.5b00763