ISSN:
1573-2932
Keywords:
ammonium
;
nitrate nitrogen
;
organic-N
;
watershed
;
weather effects
Source:
Springer Online Journal Archives 1860-2000
Topics:
Energy, Environment Protection, Nuclear Power Engineering
Notes:
Abstract We studied discharges of total-N, nitrate, ammonium, and total organic-N from seven contiguous small watersheds on the Atlantic Coastal Plain in Maryland for up to 25 yr. These watersheds have perched aquifers so all groundwater discharges as well as surface runoff were measured at V-notch weirs which included volume-integrating flow-proportional samplers. Interannual variations in annual and seasonal precipitation during this study spanned approximately the range of 160 yr weather records in the region. Annual total-N area yields from the overall watershed varied nine-fold, correlations of all N-parameter discharges with precipitation were highly significant, and power function regressions of precipitation vs N-discharge explained from 36 to 59% of the variance. Nitrogen fluxes from a cropland watershed were much higher and more variable with volume of precipitation, while fluxes from a forested watershed were much lower and were primarily composed of organic-N. Correlations of N-fluxes with precipitation were higher in the winter and spring. Annual and seasonal N-concentrations also often increased significantly with precipitation. Variations in seasonal air temperature sometimes explained significant amounts of variance in N-discharges, especially ammonium. A model composed of regressions was used to construct graphical and tabular summaries.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1005194630598
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