Selenium removal by constructed wetlands: quantitative importance of biological volatilization in the treatment of selenium-laden agricultural drainage water.
Management of selenium (Se) -contaminated agricultural drainage water is one of the most important environmental issues in California. To evaluate the feasibility of utilizing constructed wetlands to remediate Se-laden drainage water and the role of biological volatilization in Se removal, 10 flow-through wetland cells were constructed in 1996 in Corcoran, California. The monthly monitoring study from May 1997 to December 1999 showed that the vegetated wetlands were capable of significantly reducing Se from the inflow drainage water; an average of 69.2% of the total Se mass in the inflow was removed. Most of the Se was retained in sediment, and <5% of the Se was accumulated in plant tissues. Selenium volatilization was highest in the rabbitfoot grass wetland cell, where 9.4% of the Se input was volatilized over a 2-year period. Volatilization was greater in spring and summer than in fall and winter. For example, in May and June of 1998, 35 and 48%, respectively, of the Se entering the rabbitfoot grass cell was volatilized, whereas in the winter months, <5% was volatilized. The feasibility of using constructed wetlands for Se remediation, methods for the enhancement of Se volatilization, and the importance of considering potential Se ecotoxicity are discussed.
Lin
Zhi-Qing
ZQ
Department of Plant and Microbial Biology, University of California, 111 Koshland Hall, Berkeley, California 94720-3102, USA. zhlin@siue.edu
Terry
Norman
N
D000383:Agriculture; D017753:Ecosystem; D004784:Environmental Monitoring; D010944:Plants; D012621:Seasons; D012643:Selenium / Q000302:isolation & purification* / Q000493:pharmacokinetics; D014018:Tissue Distribution; D014835:Volatilization; D014873:Water Pollutants / Q000302:isolation & purification* / Q000493:pharmacokinetics; D014881:Water Supply
D014873:Water Pollutants; D012643:Selenium