Transformation and Detoxification of Halogenated Fumigants by Ammonium Thiosulfate

• Published in: Environmental science & technology Vol. 34; no. 17; pp. 3717 - 3721
• Main Authors: Wang, Q, Gan, J, Papiernik, S. K, Yates, S. R
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01-09-2000
• Subjects: 1,3-dichloropropene; ammonium thiosulfate; Applied sciences; Bacteria; Biological and medical sciences; Chemical control; chloropicrin; Control; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Global environmental pollution; methyl bromide; methyl iodide; Pesticides; Phytopathology. Animal pests. Plant and forest protection; Pollution; propargyl bromide; Protozoa. Invertebrates; Soils; Vibrio fischeri; Bioluminescence; Fumigation; Dehalogenation; Toxicity; Temperature effect; Soil pollution; Vibrio fischeri; Pest management; Chemical control; Reaction mechanism; Bacteria; Rate constant; Activation energy; Nitrogen fertilizer; Halogen Organic compounds; Ammonium Thiosulfates; Ground water; Methyl bromide; Bioassay; Mineral amendment; Pollution prevention; Fumigant; Reaction rate; Chloropicrin; Environment impact; Vibrionaceae; Air pollution; Water pollution; Kinetics; Iodomethane; Nucleophilic substitution
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es000973z

Fumigants are commonly used at high rates (100−400 kg ha-1) in warm regions to control soil-borne pests. Many fumigants, however, tend to move easily from the treated soil into the atmosphere or groundwater, resulting in air or groundwater pollution. We studied the transformation of the fumigants methyl bromide (MeBr), propargyl bromide (PBr), 1,3-dichloropropene (1,3-D), chloropicrin (CP), and methyl iodide (MeI) by fertilizer ammonium thiosulfate (ATS). All fumigants were rapidly dehalogenated by thiosulfate via nucleophilic substitution, and the rate of transformation followed the order MeBr ≈ MeI > PBr > 1,3-D > CP. For all fumigants, the reaction followed second-order kinetics with activation energy of ∼73 kJ mol-1, suggesting a similar rate-limiting step. In soil, amendment of ATS at 1.0 mmol kg-1 accelerated fumigant dissipation by 21−63 times for MeBr, MeI, and PBr and by 4.6−5.5 times for 1,3-D and CP. Preliminary toxicity assays using the luminescent bacterium Vibrio fisheri showed that ATS transformation largely eliminated the acute toxicity of fumigants to this organism. These results suggest that thiosulfate transformation of halogenated fumigants is likely a benign chemical approach that may be used for mitigating environmental and health risks in fumigation.