SS4.06 Speciation, Bioavailability, and Impacts of Atmospheric Trace Metals in Aquatic Systems
Date: Wednesday, June 12, 2002
Time: 4:30:00 PM
Location: Esquimalt
 
AmyotM, Institut national de la recherche scientifique (INRS), Sainte-Foy, Canada, marc_amyot@inrs-eau.uquebec.ca
Southworth, G, , Oak Ridge National Laboratory, Oak Ridge, USA, cgr@ornl.gov
Lindberg, S, E, Oak Ridge National Laboratory, Oak Ridge, USA, sll@ornl.gov
Hintelmann, H, , Trent University, Peterborough, Canada, hhintelmann@trentu.ca
Lalonde, J, D, Institut national de la recherche scientifique, Sainte-Foy, Canada, janick_lalonde@inrs-eau.uquebec.ca
Gilmour, C, C, The Academy of Natural Sciences Estuarine Research Center, St. Leonard, USA, , gilmour@acnatsci.org
Rudd, J, W, Freshwater Institute, Winnipeg, Canada, RuddJ@dfo-mpo.gc.ca
Kelly, C, , Freshwater Institute, Winnipeg, Canada, KellyC@dfo-mpo.gc.ca
Harris, R, , Tetra Tech Inc, Oakville, Canada, rharris6@cogeco.ca
Poulain, A, , Institut national de la recherche scientifique, Sainte-Foy, Canada, zalexp@yahoo.ca
 
EVOLUTION OF DISSOLVED GASEOUS MERCURY IN LARGE LAKE ENCLOSURES AMENDED WITH A STABLE ISOTOPE OF MERCURY
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METAALICUS (Mercury Experiment to Assess Atmospheric Loading in Canada and United States) aims at establishing the link between atmospheric deposition of mercury and mercury concentrations in fish. As part of this initiative, we conducted an enclosure experiment in Lake 239 at the Experimental Lakes Area. Our specific goal was to follow redox transformations of added 200HgCl2. Dissolved gaseous mercury (DGM, mainly Hg(0)) concentrations reached very high surface levels (up to 6 ng/L) during the days following the spike (total Hg: 20 ng/L), leading to important losses to the atmosphere. These losses may explain the decrease in total Hg observed in the enclosures over time. Photochemical experiments using enclosure waters revealed that photoreduction rates were high after spiking (1 ng/L/h) and decreased during the summer, with low rates observed in August (0.01 ng/L/h). These low rates may be caused by photobleaching of DOC in the enclosures. These results indicate that newly deposited Hg may be efficiently recycled back to the atmosphere, under certain conditions.