The biogeochemistry of metal contaminated peatlands

Shaun Watmough1, Erik Szkokan-Emilson2, Paul Pennington1, Sophie Barrett1, Laura Souter1, Myra Juckers1
1 Trent University
2 Laurentian University

O 6.6 in Biogeochemistry of wetlands

15.07.2014, 15:30-15:50, H17

Peatlands are dominant features of the Boreal landscape and are under increasing pressures from anthropogenic pollutants and climate change. This presentation synthesizes work conducted in peatlands (poor-fens) extending along a metal deposition gradient in the Sudbury region of Ontario, Canada. Peatlands located closest to the smelters are greatly enriched in Cu and Ni, although porewater chemistry is greatly influenced by the acidity of water and organic matter content.  Soil-surface partitioning of many metals (Ni, Co, Mn) can be explained by peat chemistry and porewater pH, but for others (Al, Cu) DOM is much more important.. The quantity and quality (Humification index) of dissolved organic carbon draining the peatlands is governed primarily by carbon content and quality in peat.  Porewater chemistry demonstrates tremendous temporal variability and following summer droughts the acidity of water draining the streams can fall by 1 pH unit and metal concentrations may increase 100 fold. Initially this change is brought about by the oxidation of sulphur into sulphuric acid but as droughts persist, nitrification and nitric acid production becomes increasingly important.  Currently peatlands are a source of several metals to surface waters and profiles of some metals in peat are greatly influenced by redox-induced metal mobility.  This study demonstrates natural variability in peatlands modify the negative impact of metal contamination but that climate change, and droughts in particular, can greatly enhance this stress. 

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last modified 2014-04-01