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Title: VOLATILIZATION AND DEGRADATION OF SOIL-APPLIED DIMETHYLSELENIDE

Author
item Dungan, Robert - Rob
item Yates, Scott
item FRANKENBERGER, WILLIAM - UC RIVERSIDE, CA

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/10/2002
Publication Date: 11/1/2002
Citation: DUNGAN, R.S., YATES, S.R., FRANKENBERGER, W.T. VOLATILIZATION AND DEGRADATION OF SOIL-APPLIED DIMETHYLSELENIDE. JOURNAL OF ENVIRONMENTAL QUALITY. 2002. 31(6):2045-2050.

Interpretive Summary: The formation of dimethylselenide (DMSe) is a microbially-mediated process that occurs in seleniferous environments. Dimethylselenide is a highly volatile gas, and it has been proposed that the microbial volatilization of selenium (Se) could be used to detoxify Se-contaminated soils. In this study, the degradation of DMSe was found to be due to biological processes and changes in temperature and soil moisture content had little influence on the degradation rate. Adding either 1 percent gluten or casein (by weight) to soil inhibited the degradation of DMSe. In soil columns, increasing the soil moisture content or depth to soil surface was found to significantly decrease the amount of DMSe transported to the air. Additions of 1 percent casein or gluten in the top 5 cm of soil caused higher cumulative loss of DMSe compared to unamended soil. Increasing our understanding of the soil conditions that influence the degradation and volatilization of DMSe should help to better facilitate Se volatilization as a remediation technique.

Technical Abstract: The effect of soil moisture, temperature, and organic amendments on the degradation of dimethylselenide (DMSe) was investigated. The degradation of DMSe was largely a result of biological mechanisms, however, changes in temperature (20-40 deg C) and soil moisture content (6-14 percent) had little influence on the degradation rate. In contrast, amending soil with either 1 percent gluten or casein (by weight) had an inhibitory effect on the degradation of DMSe. The transport of DMSe in packed soil columns was also investigated. Increasing the soil moisture content or depth to soil surface was found to significantly decrease the amount of DMSe transported to the air. In columns containing 1 percent casein or gluten in the top 5 cm of soil, the cumulative loss of DMSe was approximately 9percent higher than in unamended soil. Increasing our understanding of the soil conditions that influence the degradation and volatilization of DMSe should help to better facilitate Se volatilization as a remediation technique.