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Oxidation and mobilization of selenium by nitrate in irrigation drainage

Journal of Environmental Quality

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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.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Oxidation and mobilization of selenium by nitrate in irrigation drainage
Series title:
Journal of Environmental Quality
Volume
28
Issue:
4
Year Published:
1999
Language:
English
Publisher:
American Soc of Agronomy Inc
Publisher location:
Madison, WI, United States
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Environmental Quality
First page:
1182
Last page:
1187
Number of Pages:
6