The degradation of (<i>Z</i>)‐ and (<i>E</i>)‐1,3‐dichloropropenes and 1,2‐dichloropropane in soil

Abstract

Abstract The degradation in soil of the major constituents of a 1,3‐dichloropropene‐1,2‐dich‐loropropane nematicide has been studied under laboratory and outdoor conditions. In sealed glass containers, ( Z )‐ and ( E )‐1,3‐dichloropene‐ 2 ‐ 14 C were converted in soil into the corresponding 3‐chloroallyl alcohols and these alcohols were in part strongly bound to the soil. The ( Z )‐ and ( E )‐3‐chloroacrylic acids were also found as minor products. More polar products were detected and these released the chloroacrylic acids in 20–30% yield upon hydrolysis. Although the 1,3‐dichloropropenes were lost by volatilisation from soil stored in open glass jars outdoors, they also underwent degradation to the same products that were detected in sealed containers. There was evidence of only slight degradation of 1,2‐dichloropropane‐ 2 ‐ 14 C (4 % or less of the applied radioactivity remained unextracted from a loam soil after 5 months). When soil treated with the 1,2‐dichloropropane was stored outdoors in an open glass container, less than 1 % of the original radiolabel remained in the soil after 10 days under these conditions due to volatilisation of the applied material. In a separate experiment potatoes were grown in soil 6 months after treatment with a mixture of both ( Z )‐ and ( E )‐1,3‐dichloropropene‐ 2 ‐ 14 C and 1,2‐dichloropropane‐ 2 ‐ 14 C. Although 5 % of the applied radiolabel remained in the soil at potato harvest the potato tubers contained only a very small residue (0.007 mg/kg).