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CARBON TRACE GASES IN LAKE AND BEAVER POND ICE NEAR THOMPSON, MANITOBA, CANADA
Kuhlbusch, T. A. AND R G. Zepp. CARBON TRACE GASES IN LAKE AND BEAVER POND ICE NEAR THOMPSON, MANITOBA, CANADA. JOURNAL OF GEOPHYSICAL RESEARCH 104(D22):27693-27698, (1999).
The overall objective of this task is to develop quantitative relationships for assessing the vulnerability of aquatic resources to global change. The task will contribute experimental and modeling tools for assessments of the interactions of global climate and UV changes with coral reefs and selected watersheds and estuaries in the U.S. These activities are contributing primarily to two APGs in the ecosystems component of the Global Change Research Multiyear Plan: the 2006 APG (APG 3) on building the capacity to assess global change impacts on coastal aquatic ecosystems, including coral reefs and estuaries and the 2004 APG (APG 2) on building capacity to assess and respond to global change impacts on selected watersheds. One major task objective is to assess interactions of global warming and UV exposure that are contributing to the observed coral bleaching and disease. Our lab is working with scientists at the NHEERL Gulf Ecology Lab to characterize UV exposure and effects at several coral reef sites. Other research in this task is examining the interactions between UV-induced breakdown of refractory organic matter in estuaries and coastal areas that enhance UV penetration into the water and concurrently form biologically-labile nitrogen-, phosphorus- and carbon-containing substances that stimulate productivity and microbial activity. This task also involves research in central Brazil that is part of the Large Scale Biosphere Atmosphere Experiment (LBA). The objectives of this project are to assess the impacts of land use and climatic changes on soil nutrient cycles and microbiota, trace gas exchange and water quality in the Brazilian cerrado. This work involves a close collaboration between EPA and a group of scientists from the Department of Ecology, University of Brasilia, Brazil. Other objectives of this task are to assess the interactions of land use and climate changes with the ecological functioning of streams in watersheds of the Piedmont region of the southestern U.S.
Concentrations of CO2, CO, and CH4 were measured in beaver pond and lake ice in April 1996 near Thompson, Manitoba to derive information on possible impacts of ice melting on corresponding atmospheric trace gas concentrations. CH4 concentrations in beaver pond and lake ice ranged between 0.3-150 mmol m(-3) and 3.1-56.2 mu mol m(-3), respectively. The corresponding CO concentrations showed no significant differences between the two lakes. They varied between 50 and 250 mu mol m(-3). These CO concentrations are some of the highest determined in any aquatic system. The differences in CH4 concentrations between lake and pond can be explained by the differences in production and microbial oxidation rates
between the two systems. No explanation can be given for the similar CO concentrations. Supersaturation factors for CO were 660+/-130 and 630+/-330, and 65-35000 and 0.6-13 for CH4 in the ice of the beaver pond and Troy Lake, respectively. When digging into the beaver pond ice, a continuous flow of bubbles with 0.32+/-0.06 vol% CH4, 2.2+/-0.3 vol% CO2, and
482+/-98 ppb CO coming out of the slash ice for about 20-30 minutes was noticed. Wintertime flux estimates of CH4 and CO showed that they represent at minimum 6.4 % and 2.2 % of that of the summer. It has to be noted that these wintertime fluxes will mostly be released to the atmosphere during the time of snowmelt, thus a limited time period of weeks.
Record Details:Record Type: DOCUMENT (JOURNAL/PEER REVIEWED JOURNAL)
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL EXPOSURE RESEARCH LABORATORY
ECOSYSTEMS RESEARCH DIVISION