Competitive degradation between the fumigants chloropicrin and 1,3-dichloropropene in unamended and amended soils

ABSTRACT Indianapolis, IN) have been developed as commercial formulations.The mixture of 1,3-dichloropropene (1,3-D) and chloropicrin (CP) Fumigants have high vapor pressures and are trans-is used as a preplant soil fumigant. In comparison with individual ported predominantly in the vapor phase. Excessivefumigants, application of a mixture may affect the environmental emissions of their vapor into the atmosphere may con-dissipation and fate of each chemical, such as emission and degrada-tribute to air pollution and cause adverse effects ontion. We investigated the degradation of CP, 1,3-D, and their mixture in fresh soils and sterile soils, and evaluated the competitive character- human and environmental health. Because many fumi-istic of fumigants in the mixture. The degradation of low concentra- gants have acute and chronic toxicity, genotoxicity, or tions of CP in fresh soil was accelerated at early times in the presence carcinogenicity, their emissions have caused wide con-of 1,3-D, whereas the addition of CP reduced the degradation rate cern and excessive concentrations in air have triggered of trans-1,3-D, possibly by inhibiting the activity of trans-1,3-D de- restrictions of their use. For instance, high 1,3-D concen-grading microorganisms. The potential of applying amendments to trations were detected in the ambient air near fumigated the soil to increase the rate of CP and 1,3-D degradation was also fields in 1990, resulting in a four-year suspension ofillustrated. The degradation of both fumigants was significantly en-1,3-D use in California (California Department of Foodhanced in soils amended with ammonium thiosulfate (ATS) and so-and Agriculture, 1990). Airborne levels of CP deter-dium diethyldithiocarbamate (Na-DEDTC) compared with unamende