HR: 0800h
AN: B11B-0390    [Abstracts]
TI: Changes in Total and Methyl Mercury Concentrations and Fluxes Resulting From Clearcut Logging and Drought in Boreal Forest Wetlands and Hillslope Groundwaters
AU: * Allan, C J
EM: cjallan@uncc.edu
AF: Dept. of Geography and Earth Sciences UNC Charlotte, 9201 University City Blvd., Charlotte, NC 28223, United States
AU: Heyes, A
EM: heyes@cbl.umces.edu
AF: Chesepeake Biological Laboratory University of Maryland, 1 Williams St. PO Box 38, Solomons, Md 20688, United States
AU: Mackereth, R
EM: rob.mackereth@mnr.gov.on.ca
AF: Center for Northern Forest Ecosystem Research Ontario Ministry of Natural Resources, 955 Oliver Rd, Thunder BAy, Ont P7B 5E1, Canada
AB: Two zero order boreal forest catchments in NW Ontario have been hydrochemically monitored since spring 2003. One of the cathcments, E1 was clearcut logged during mid summer 2004. Ground and surface water samples have been analyzed for Total and Methyl Hg THg, MeHg), DOC, major ion and nutrient concentrations over the duration of the project. Contrary to results from northern European forestry studies no significant changes in MeHg or THg concentrations in ground or surface waters were measured in the first two years after logging. However, there was approximately a two-fold increase in Hg transport from the logged watershed as a result of the increased runoff flux. Internal mass balance estimates suggest that proportion of MeHg contributed from a valley bottom has doubled in relation to MeHg contributions from logged hillslopes during the initial post harvest period. Conversely, the proportion of THg contributed from hillslope soils has increased by 80% during the post logging period in comparison to the valley bottom wetland. During 2006 the study site experience a severe drought with precipitation levels approximately 50% of normal. THg surface and groundwater concentrations in both the logged and reference watershed have increased on average two to six fold upon the resumption of more normal precipitation levels during the first half of 2007.
DE: 0432 Contaminant and organic biogeochemistry (0792)
DE: 0497 Wetlands (1890)
DE: 1632 Land cover change
SC: Biogeosciences [B]
MN: 2007 Fall Meeting