ISSN:
1573-515X
Keywords:
acid deposition
;
atmospheric deposition
;
nitrate
;
nitrification
;
nitrogen
;
soil carbon
;
soil chemistry
;
stream water acidification
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Geosciences
Notes:
Abstract Cumulative effects of atmospheric N deposition mayincrease N export from watersheds and contribute tothe acidification of surface waters, but naturalfactors (such as forest productivity and soildrainage) that affect forest N cycling can alsocontrol watershed N export. To identify factors thatare related to stream-water export of N, elevationalgradients in atmospheric deposition and naturalprocesses were evaluated in a steep, first-orderwatershed in the Catskill Mountains of New York, from1991 to 1994. Atmospheric deposition of SO 4 2− , andprobably N, increased with increasing elevation withinthis watershed. Stream-water concentrations ofSO 4 2− increased with increasing elevationthroughout the year, whereas stream-waterconcentrations of NO 3 − decreased withincreasing elevation during the winter and springsnowmelt period, and showed no relation with elevationduring the growing season or the fall. Annual exportof N in stream water for the overall watershed equaled12% to 17% of the total atmospheric input on thebasis of two methods of estimation. This percentagedecreased with increasing elevation, from about 25%in the lowest subwatershed to 7% in the highestsubwatershed; a probable result of an upslope increasein the thickness of the surface organic horizon,attributable to an elevational gradient in temperaturethat slows decomposition rates at upper elevations. Balsam fir stands, more prevalent at upper elevationsthan lower elevations, may also affect the gradient ofsubwatershed N export by altering nitrification ratesin the soil. Variations in climate and vegetationmust be considered to determine how future trends inatmospheric deposition will effect watershed export ofnitrogen.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1006332230890
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