| Abstract: | Selenium (Se) can be oxidized by nitrate (NO3-) from irrigation on Cretaceous marine shale in western Colorado. Dissolved Se concentrations are positively correlated with dissolved NO3- concentrations in surface water and ground water samples from irrigated areas. Redox conditions dominate in the mobilization of Se in marine shale hydrogeologic settings; dissolved Se concentrations increase with increasing platinum-electrode potentials. Theoretical calculations for the oxidation of Se by NO3- and oxygen show favorable Gibbs free energies for the oxidation of Se by NO3-, indicating NO3- can act as an electron acceptor for the oxidation of Se. Laboratory batch experiments were performed by adding Mancos Shale samples to zero- dissolved-oxygen water containing 0, 5, 50, and 100 mg/L NO3- as N (mg N/L). Samples were incubated in airtight bottles at 25??C for 188 d; samples collected from the batch experiment bottles show increased Se concentrations over time with increased NO3- concentrations. Pseudo first-order rate constants for NO3- oxidation of Se ranged from 0.0007 to 0.0048/d for 0 to 100 mg N/L NO3- concentrations, respectively. Management of N fertilizer applications in Cretaceous shale settings might help to control the oxidation and mobilization of Se and other trace constituents into the environment. |
| Genre: | Article |
| ProdID: | 70021956 |
| Citation Author: | Wright, W. G. |
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| Citation End Page: | 1187 |
| Citation Issue: | 4 |
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| Citation Language: | English |
| Citation Larger Work Title: | Journal of Environmental Quality |
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| Citation Number Of Pages: | 6 |
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| Citation Publisher: | American Soc of Agronomy Inc |
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| Citation Search Results Text: | Oxidation and mobilization of selenium by nitrate in irrigation drainage; 1999; Article; Journal; Journal of Environmental Quality; Wright, W. G. |
| Citation Start Page: | 1182 |
| Citation Volume: | 28 |
| Citation Year: | 1999 |
| Type: | citation/reference |
| Text: | Oxidation and mobilization of selenium by nitrate in irrigation drainage; 1999; Article; Journal; Journal of Environmental Quality; Wright, W. G. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Fri, 1 Jan 1999 00:00 -0600 |
| Publisher: | American Soc of Agronomy Inc |
