HR: 1340h
AN: H13F-0475    [Abstracts]
TI: Are Brook Trout Streams in Western Virginia and Shenandoah National Park Recovering from Acidification?
AU: * Webb, J R
EM: rwebb@virginia.edu
AF: Hydrology, Department of Environmental Sciences, University of Virginia, Charlottesville, VA 22903 United States
AB: Stream water composition data obtained through periodic sampling of small mountain headwater streams in Shenandoah National Park (SNP) and western Virginia were examined for evidence of change in acid-base status. Decreasing concentrations of sulfate and increasing concentrations of acid-neutralizing capacity (ANC) in stream waters of SNP during the 1988-2001 period are consistent with recovery from acidification, whereas changes in the concentration of these constituents in stream waters of the larger western Virginia region during the same period are consistent with continued acidification. Although the observed changes in the composition of streams in SNP represent an improvement over acidification trends observed in the 1980s, the degree of apparent recovery is relatively minor in relation to recovery observed in other regions, in relation to estimated historic stream acidification in SNP, and in relation to potential biological significance. In addition, a transient increase in concentrations and export of nitrate in SNP stream waters following forest defoliation by the gypsy moth complicates interpretation of trends in acid-base status and may account for much of the apparent recovery from acidification. An overview of regional trends in ANC and sulfate concentrations suggests the presence of a north-south gradient in surface water recovery from acidification, consistent with expectations based on regional differences in watershed retention of sulfur.
DE: 1803 Anthropogenic effects
DE: 1806 Chemistry of fresh water
DE: 1871 Surface water quality
DE: 1615 Biogeochemical processes (4805)
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting