PERSISTENCE AND MOVEMENT OF α- AND γ-CHLORDANE IN SOILS FOLLOWING TREATMENT WITH HIGH-PURITY CHLORDANE (VELSICOL HCS-3260)

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Abstract
Residues from high-purity chlordane (Velsicol HCS-3260) were determined in British Columbia soils for 16 mo following applications in June 1971 at two rates of 5.6 and 11.2 kg active ingredients (a.i.)/ha. Residues from a cool, moist location declined rapidly during the 1st mo following application, with greater percentage loss from the lower application rate. From the 2nd mo until 16 mo after application, decay rates were linear with time. Although 225 cm rain fell during this period, less than 2% of the total residues reached the 15–23-cm horizon. Calculated half-lives were 4 and 11 mo, respectively. Residues from a semiarid location were more persistent and did not decline rapidly within the 1st mo after application. Possible reasons for these differences are discussed. Leaching experiments with five different soil types in the laboratory confirmed the limited movement of chlordane observed in field soil.