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STREAM WATER CHEMISTRY IN WATERSHEDS RECEIVING DIFFERENT ATMOSPHERIC INPUTS OF H + , NH 4 , NO 3 − , AND SO 4 2−1
Author(s) -
Stottlemyer Robert
Publication year - 1997
Publication title -
jawra journal of the american water resources association
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.957
H-Index - 105
eISSN - 1752-1688
pISSN - 1093-474X
DOI - 10.1111/j.1752-1688.1997.tb04104.x
Subject(s) - precipitation , watershed , hydrology (agriculture) , soil water , chemistry , streams , meltwater , water year , environmental science , environmental chemistry , water resources , snow , geology , ecology , geography , soil science , geomorphology , meteorology , computer network , geotechnical engineering , machine learning , computer science , biology
Weekly precipitation and stream water samples were collected from small watersheds in Denali National Park, Alaska, the Fraser Experimental Forest, Colorado, Isle Royale National Park, Michigan, and the Calumet watershed on the south shore of Lake Superior, Michigan. The objective was to determine if stream water chemistry at the mouth and upstream stations reflected precipitation chemistry across a range of atmospheric inputs of H + , NH 4 + , NO 3 − − , and SO 4 2− . Volume‐weighted precipitation H + , NH 4 + , NO 3 − − , and SO 4 2− concentrations varied 4 to 8 fold with concentrations highest at Calumet and lowest in Denali. Stream water chemistry varied among sites, but did not reflect precipitation chemistry. The Denali watershed, Rock Creek, had the lowest precipitation NO 3 − − and SO 4 2− concentrations, but the highest stream water NO 3 − and SO 4 2− concentrations. Among sites, the ratio of mean monthly upstream NO 3 − − concentration to precipitation NO 3 − ‐ concentration declined (p < 0.001, R 2 = 0.47) as precipitation NO 3 − − concentration increased. The ratio of mean monthly upstream to precipitation SO 4 2− concentration showed no significant relationship to change in precipitation SO 4 2− concentration. Watersheds showed strong retention of inorganic N (> 90 percent inputs) across inputs ranging from 0.12 to > 6 kg N ha −1 y −1 . Factors possibly accounting for the weak or non‐existent signal between stream water and precipitation ion concentrations include rapid modification of meltwater and precipitation chemistry by soil processes, and the presence of unfrozen soils which permits winter mineralization and nitrification to occur.