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Variations in Base-Flow Nitrate Flux in a First-Order Stream and Riparian Zone
- Nonpoint source pollution, which contributes to contamination of surface waters, is difficult to control. Some pollutants, particularly nitrate (NO₃⁻), are predominantly transmitted through ground water. Riparian buffer zones have the potential to remove contaminants from ground water and reduce the amount of NO₃⁻ that enters surface water. This is a justification for setting aside vegetated buffer strips along waterways. Many riparian zone hydrologic models assume uniform ground-water flow through organic-rich soil under reducing conditions, leading to effective removal of ground-water NO₃⁻ prior to discharge into a stream. However, in a small first-order stream in the mid-Atlantic coastal plain, base-flow generation was highly variable (spatially and temporally). Average base-flow NO₃⁻ 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 NO₃⁻ ground water than others. Areas within the riparian zone responsible for most of the NO₃⁻ exported from the watershed are termed "critical areas." Over this 5-year study, most of the NO₃⁻ exported during base flow 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 should be a priority for continued riparian zone research.
Angier, J.T. , McCarty, G.W.
base flow , streams , water pollution , nitrates , riparian areas , nonpoint source pollution , riparian buffers , groundwater contamination , hydrologic models , coasts , spatial variation , temporal variation , pollution load , winter , summer , wet environmental conditions , dry environmental conditions , wetlands , agricultural watersheds , Maryland , Atlantic Ocean
- Includes references
- Journal of the American Water Resources Association 2008 Apr., v. 44, no. 2
Journal Articles, USDA Authors, Peer-Reviewed
- Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.