Longitudinal and seasonal patterns of stream acidity in a headwater catchment on the Appalachian Plateau, West Virginia, U.S.A.

Author: Fitzhugh* R.D.  

Publisher: Springer Publishing Company

ISSN: 0168-2563

Source: Biogeochemistry, Vol.47, Iss.1, 1999-10, pp. : 39-62

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Abstract

The chemical composition during baseflow was used to elucidate the fundamental processes controlling longitudinal and seasonal patterns of stream acidity in Yellow Creek, a chronically acidic headwater (pH range 3.7--4.2) on the Appalachian Plateau in northeastern West Virginia. Sulfate concentrations controlled the variability of stream acidity within the Yellow Creek catchment. Decreases in stream free H^plus acidity with decreasing elevation likely resulted from SO_4^2 minus retention in riparian wetland areas as well as spatial variation in dominant tree species. Seasonal variations in free H^plus and inorganic monomeric aluminum (Al^n plus) concentrations appeared related to seasonal fluctuations in baseflow discharge which was controlled by vegetative activity. Baseflow stream discharge, as well as H^plus and Al^n plusacidity, gradually declined during the growing season (June through October), likely reflecting microbial SO_4^2 minus reduction in saturated anaerobic environments within riparian wetlands. A marked pulse of stream H^plus, Al^n plus, and SO_4^2 minuscoincided with an abrupt increase in baseflow discharge resulting from the cessation of transpiration after leaf-fall in November. This seasonal pattern suggests that autumn may be a critical period for eastern brook trout in streams draining wetlands on the Appalachian Plateau.

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