Branfireun, B. A.. University of Toronto at Mississauga,
Roulet, N. A.. McGill University,
Nilsson, M. University of Umea,
Bishop, K. Swedish University of Agricultural Sciences,
Granberg, G. University of Umea,

Recent studies have found that some peatland sediments have highly elevated methylmercury (MeHg) concentrations, and that peatlands may act as sources of methylmercury to downstream aquatic systems. Sulfate-reducing bacteria have been implicated as methylators of inorganic mercury in many environments. This paper describes experiments undertaken to determine if observed high concentrations of MeHg could be the result of increased activity of sulfate-reducing bacteria in peatlands. Experiments in a poor fen in the Experimental Lakes Area, northwestern Ontario, Canada, demonstrated that sulfate additions 2 and 20 times that of the average monthly wet sulfate deposition to in situ peat and peat pore water resulted in a transient 5 to 10-fold increase in pore water MeHg concentrations over 5 days. A three year experiment in a mire near Umeň, Sweden, was undertaken in which sulfate additions 3.3 and 6.6 times the local rate of deposition were made to experimental plots. Pore water MeHg concentrations in the manipulated plots were 1.8 and 3.5 times higher than background MeHg respectively. These findings indicate that chronically elevated levels of atmospheric sulfate deposition to peatlands may result in higher peatland pore water MeHg concentrations and catchment MeHg yields.
Day: Tuesday, Feb. 2
Time: 12:15 - 12:30pm
Location: Sweeney Center
Code: SS07TU1215S