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Submitted to: Plant and Soil
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 1/1/2000 Publication Date: N/A Citation: N/A Interpretive Summary: Drainage water reuse is proposed for reducing the volume of saline drainage water in the west side of central California. Saline effluent collected in some regions of central California contains potentially a new hazard to long term reuse, namely the presence of selenium. Phytoextraction of selenium is a proposed strategy for reducing Se levels in irrigated agricultural soils. The objective of this study is to determine the efficiency of canola, Indian mustard, and barley to extract selenium from soils irrigated with selenium-laden effluent. The results show that accumulation of selenium by both canola and Indian mustard significantly reduced the residual selenium deposited in the soil by the effluent. In addition to plant accumulation of selenium, leaching and possibly volatilization contributed to losses of residual selenium. Long-term field studies are essential to determine the potential effectiveness of canola and Indian mustard to tolerate poor quality water, and extract and volatilize selenium under hot summer conditions present in central California. Technical Abstract: Vegetation management or phytoremediation of selenium (Se) is a recently proposed strategy for reducing Se levels in the soil irrigated with a Se- laden effluent. Selenium accumulation and Se extraction by two Brassica species, canola and Indian mustard, and barley was evaluated under greenhouse conditions. In Study 1, treatments consisted of irrigating the noted plant species with an effluent containing .15 mg Se/L, 10 mg B/L, and EC of 10 dS/M. In Study 2, soils were pre-loaded with Se at 2 mg Se/L, boron (B) at 10 mg B/L, and salts to achieve an EC of 8 dS/M. In Study 1, Se concentrations averaged 22 mg Se/kg DM in both Brassica species and 4 mg Se/kg DM in barley. Losses of soil Se were as high as 40% for the Brassica and 20% for barley. Approximately 50% and 12% of the lost soil Se was recovered in the Brassica shoots and barley, respectively. In Study 2, Se concentrations averaged 75 and 12 mg Se/kg DM in both Brassica species and barley, respectively. Approximately 60 and 23% of the lost soil Se was accumulated in Brassica and barley, respectively. In both studies, leaching and presumably biological volatilization also contributed to soil Se losses. Results from both studies indicate that the tested Brassica species were most effective for removing Se added to soil via use of Se- laden effluent. The study is presently being conducted under field conditions. |
