1987 Volume 22 Issue 4 Pages 278-285
A potentially important source of atmospheric selenium is natural volatilization by biomethylation. This study was carried out to ascertain the quantity of selenium that could be volatilized into the atmosphere from soils by methylation when selenite was added under aerobic and anaerobic conditions. A reaction flask containing soil sample was placed in an incubator and a stream of air or nitrogen was passed through the flask to sweep the volatile selenium compounds present in the headspace into a nitric acid trap. No volatilization of selenium occurred when soils are sterilized. Soil microorganisms play an important part in the process of selenium volatilization. The release of volatile selenium compounds from soils is greatly influenced by various factors including temperature, pH, moisture, light, presence of supplementary nutrient for microorganisms, addition of antibiotic substance, and biochemical availability of selenium. The total amounts of selenium compounds volatilized from soils containing 1% of glucose ranged from 0.26 to 7.2% of that added as sodium selenite. Microbial growth rate seems to have some positive influence on the volatilization rate of selenium. The volatilization of selenium was enhanced greatly in the case when the soil was supplemen ted with nutrients to stimulate microbial growth.
