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Communication at the NABS Annual meeting, Keystone, 2000
(143) DENITRIFICATION IN SEDIMENTS FROM HEADWATER STREAMS IN THE SOUTHERN APPALACHIAN MOUNTAINS, USA.
L.A. Martin1, P.J. Mulholland2, J.R. Webster1, and H.M. Valett1. 1Department of Biology, Virginia Polytechnic Institute & State University, Blacksburg, VA 24061-0406, 2Oak Ridge National Laboratory, Environmental Sciences Division, P.O. Box 2008, Oak Ridge, TN 37831-6036
We investigated seasonal variations in resource availability (nitrate and labile organic carbon, LOC) as determinants of denitrification in sediments of streams in the southern Appalachian Mountains, USA. Stream water and sediments were sampled seasonally in two streams of contrasting nitrate availability, Noland Creek and Walker Branch. Eight additional streams with varying nitrate levels were sampled once during summer. Stream sediments were incubated at ambient stream temperatures, and nitrous oxide accumulation was quantified following acetylene inhibition of nitrous oxide reduction. Denitrification potential was greater in Noland Creek than Walker Branch, and was generally greater in sediments from the higher-nitrate streams. In autumn and spring, we studied the effects of resource limitations on denitrification via nitrate and LOC amendments. Denitrification potential in Walker Branch sediments appears to be nitrate limited, with temperature having little effect on rates. Denitrification potential in Noland Creek was not limited by nitrate, but temperature had a significant effect. When Noland Creek seasonal data were corrected to a common temperature, however, no seasonal differences in denitrification potential were detected. We found that nitrate availability, more than LOC availability, controls potential denitrification in these streams.
Presented at 2:00 PM on Tuesday, May 30, 2000 in Nutrient Processes in Sediment
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