Soil as a terrestrial sink for methyl bromide fumigant: Preliminary results

Air and surface soil samples were taken at three stations downwind of a strip of soil fumigated with injected methyl bromide. Integrated horizontal flux of methyl bromide at each sampling station showed the removal of 46% of the methyl bromide mass from the plume by the time it reached 30–60 m downwind. Based on the U.S. EPAʹs dispersion model SCREEN-3, a mass loss of 42% was estimated. Analysis of the surface soil samples indicated the presence of methyl bromide residues that declined in concentration with distance downwind from the source. Laboratory tests confirmed the first-order rapid uptake (2–4 minutes) of methyl bromide by field soil.