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Title: Nitrogen Export from a First Order Watershed in the Mid-Atlantic Coast Plain, Maryland

Author
item McCarty, Gregory
item ANGIER, JONATHAN - EPA/PESTICIDE PROGRAMS

Submitted to: International Nitrogen Conference
Publication Type: Abstract Only
Publication Acceptance Date: 10/1/2007
Publication Date: 10/1/2007
Citation: McCarty, G.W., Angier, J. 2007. Nitrogen export from a first order watershed in the Mid-Atlantic Coastal Plain, Maryland [abstract]. Proceedings of the Fourth International Nitrogen Conference. p. 160.

Interpretive Summary:

Technical Abstract: The ability of riparian ecosystems to remove nitrate from exfiltrating groundwater may be an important control on export of nitrogen from first order catchments. Many riparian zone hydrologic models assume uniform groundwater flow through organic-rich soil under reducing conditions, leading to effective removal of groundwater nitrate prior to discharge into a stream. However, in a small first-order stream in the mid-Atlantic coastal plain, baseflow generation was highly variable (spatially and temporally). Average baseflow nitrate loads were greater in winter than summer, and higher during a wetter year than in dryer years. Specific sections of the stream consistently received greater amounts of high nitrate groundwater than others. Areas within the riparian zone responsible for most of the nitrogen exported from the watershed are termed “critical areas.” Over this 5-year study most of the nitrogen exported during baseflow originated from a critical area comprising less than 10% of the total riparian zone land area. Allocation of resources to address and improve mitigation function in critical areas within riparian buffers is important for improving the efficiency of nitrogen removal by these ecosystems.