Title |
Transport and Fate of Nitrate at the Ground‐Water/Surface‐Water Interface
|
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Published in |
Journal of Environmental Quality, May 2008
|
DOI | 10.2134/jeq2006.0550 |
Pubmed ID | |
Authors |
Larry J. Puckett, Celia Zamora, Hedeff Essaid, John T. Wilson, Henry M. Johnson, Michael J. Brayton, Jason R. Vogel |
Abstract |
Although numerous studies of hyporheic exchange and denitrification have been conducted in pristine, high-gradient streams, few studies of this type have been conducted in nutrient-rich, low-gradient streams. This is a particularly important subject given the interest in nitrogen (N) inputs to the Gulf of Mexico and other eutrophic aquatic systems. A combination of hydrologic, mineralogical, chemical, dissolved gas, and isotopic data were used to determine the processes controlling transport and fate of NO(3)(-) in streambeds at five sites across the USA. Water samples were collected from streambeds at depths ranging from 0.3 to 3 m at three to five points across the stream and in two to five separate transects. Residence times of water ranging from 0.28 to 34.7 d m(-1) in the streambeds of N-rich watersheds played an important role in allowing denitrification to decrease NO(3)(-) concentrations. Where potential electron donors were limited and residence times were short, denitrification was limited. Consequently, in spite of reducing conditions at some sites, NO(3)(-) was transported into the stream. At two of the five study sites, NO(3)(-) in surface water infiltrated the streambeds and concentrations decreased, supporting current models that NO(3)(-) would be retained in N-rich streams. At the other three study sites, hydrogeologic controls limited or prevented infiltration of surface water into the streambed, and ground-water discharge contributed to NO(3)(-) loads. Our results also show that in these low hydrologic-gradient systems, storm and other high-flow events can be important factors for increasing surface-water movement into streambeds. |
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Geographical breakdown
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Colombia | 1 | 1% |
Switzerland | 1 | 1% |
France | 1 | 1% |
Italy | 1 | 1% |
New Zealand | 1 | 1% |
Argentina | 1 | 1% |
Unknown | 67 | 92% |
Demographic breakdown
Readers by professional status | Count | As % |
---|---|---|
Student > Master | 19 | 26% |
Researcher | 14 | 19% |
Student > Doctoral Student | 9 | 12% |
Student > Ph. D. Student | 8 | 11% |
Professor | 5 | 7% |
Other | 8 | 11% |
Unknown | 10 | 14% |
Readers by discipline | Count | As % |
---|---|---|
Environmental Science | 20 | 27% |
Earth and Planetary Sciences | 19 | 26% |
Agricultural and Biological Sciences | 7 | 10% |
Engineering | 6 | 8% |
Medicine and Dentistry | 2 | 3% |
Other | 4 | 5% |
Unknown | 15 | 21% |