Leaching behavior of chlorinated hydrocarbon soil fumigants in repacked soil columns

The leaching behavior of Telone (active ingredients 1,3-dichloropropene and 1,2-dichloropropane) and Telone II (active ingredient 1,3-dichloropropene) and the trace chlorinated hydrocarbon impurities in the fumigant formulations including 1,2,2-trichloropropane; 1,2,3-trichloropropane; 2,3-dichloropropene; and 1,3-dichloropropane, were studied using 75 cm long repacked soil columns in two experiments. In Exp. 1, soil columns received Telone, Telone II, or no soil fumigant. In Exp. 2, Telone II was applied to soil columns containing four soils: surface or subsurface samples from coarse- and medium-textured soils. The concentrations of the chlorinated hydrocarbon compounds were measured in the soil and leachate. The concentrations of 3-chloroallyl alcohol and 3-chloroacrylic acid, breakdown products of 1,3-dichloropropene, were also measured in leachate after Telone application. 1,3-Dichloropropene, 3-chloroallyl alcohol, and 3-chloroacrylic acid degraded rapidly, and exhibited minimal adsorption to the soil. The remaining compounds were persistent in soil. Recovery of the applied compounds was lower in the surface than in the subsurface soils, particularly in the medium-textured soil, likely due to greater biological activity in the surface soils. The risk of loss of these compounds from the root zone was minimal for 1,3dichloropropene, and lower with use of Telone II than of Telone. 1,2,2-Trichloropropane was identified as the compound in Telone II most likely to result in groundwater contamination. Significant recovery of the chlorinated hydrocarbon compounds from the control treatment, using soil that had received prior fumigant applications, suggests that these compounds may be released from soil well after the time of fumigant application.