Broad spectrum haloorganic biocides are widely employed as soil fumigants to combat the destructive action of plant parasitic nematodes and fungi. The actual fate of alkyl halides in soil along with their means of intoxication and metabolism is only beginning to be defined. However, knowledge of these processes is essential for their continued safe utilization as environmental drugs. The current project is a part of ongoing work in the author's laboratory aimed at mapping the chemical and biochemical fate of alkyl halide biocides in soil. Our general objectives is to map enough biodehalogenation processes such that the fate of a given haloorganic substance in the biosphere might be predicted and modes of intoxication by it might be delineated. For more chemically reactive organic halides, a determination of the nature of nonbiochemical transformations is equally important to understanding the "environmental metabolism" of a given substrate. The current project is focused upon two particularly toxic substrates for which information is notably meager: methyl bromide and chloropicrin. The specific aim of this proposal is to determine the possible chemical and biochemical fate of these substances in soil. Their path(s) of metabolism to nontoxic substances (if it occurs) is to be determined.