Selenium Biomethylation Products from Soil and Sewage Sludge

Abstract

Inorganic selenium compounds are converted to volatile methylated species (dimethyl selenide, dimethyl diselenide, and dimethyl selenone or methyl methylselenite) by microorganisms in sewage sludge and soil. In the absence of added selenium, no volatile selenium compounds were detected. All samples were evaluated without the addition of nutrients and in the presence of air or nitrogen. The methylation process may be an important step in the detoxification process for microorganisms exposed to high concentrations of selenium.

Hydrological and geochemical investigations of selenium behavior at Kesterson Reservoir

“…Selenite, which is stable under moderately reducing conditions, is soluble, but can strongly adsorb onto surfaces of common soil minerals and organic matter (Geering et al, 1968;Hingston et al, 1971;Hamdy et al, 1977;Balistrieri and Chao, 1987;Bar-Yosef and Meek, 1987;Neal et al, 1987;Christensen et al, 1989). Organo-selenium species include seleno-amino acids and volatile methylated Se compounds (Reamer and Zoller, 1980;Zieve and Peterson, 1981 ;Doran, 1982;Thompson-Eagle and Frankenberger, 1989). The essential role of microorganisms in catalyzing most Se transformations of environmental importance is now well-recognized (Doran, 1982;Zehr and Oremland, 1987;Jacobs, 1989;Macy et al, 1989;Oremland et al, 1989Oremland et al, , 1990Lortie et al, 1992;Frankenberger and Benson, 1994).…”

Freshwater Bacteria Can Methylate Selenium through the Thiopurine Methyltransferase Pathway

“…These forms are immobilized in the organic matter through microbial assimilation into amino acids and proteins and are mobilized in the atmosphere through biological methylation (7,12). It is noteworthy that in remote areas atmospheric concentrations of Se are far greater than the concentrations predicted to result from anthropogenic sources, suggesting that natural biological methylation is a key process involved in the flux of selenium in the atmosphere (17,27).…”

Determination of trimethylselenonium ion and i ts behavior in soil

“…Based on the fact that gaseous selenium compounds evolved from soil could not be completely trapped into the HN0 3 by the experimental system used, it is assumed that a considerable quantity of gaseous selenium compounds may be formed in the incubation system. The results reported by Doran and Alexander (1976), Reamer and Zoller (1980), and Karlson and Frankenberger (1988) suggest that DMSe is one of the major gaseous selenium compounds. We were also able to detect a small amount of DMSe in the head space of the incubation system by gas chromatography.…”