Soil Properties and Factors Influencing Aldrin-Dieldrin Recovery and Transformation1

Abstract

Variations in insecticidal effectiveness of aldrin and dieldrin in two different soils led to investigation of the persistence and possible transformation under field conditions. After 21 months, nearly one-half of the 5.4 p.p.m. of aldrin originally applied was lost, although a significant amount was recovered as dieldrin. Dieldrin loss from dieldrin-treated plots was less than aldrin Joss from aldrin-treated plots, and no significant transformation to aldrin was detected. Microbial activity appeared to be unimportant in these changes. Aldrin and dieldrin recoveries did not appear to correlate with buffer capacity, ammonium-binding power, cation exchange capacity, mechanical analysis, moisture tension, pH or chemical analyses of the soils. No single soil property appeared responsible for variations in effectiveness of the two insecticides. Properties found sufficiently different in the two soils to indicate that they may be concerned with this problem were their cation exchange capacities and their calcium and magnesium contents. The phenylazide method used on extracts of 20-gram soil samples was sensitive to 0.2 p.p.m. of aldrin and 0.4 p.p.m. of dieldrin. The method for extraction of aldrin needs additional investigation, Successive extractions with the usual aldrin solvent, Skellysolve B, gave higher recovery than single extraction. The dieldrin solvent, Skellysolve B plus 25% acetone, gave greater recovery of aldrin from soil with a single extraction. It appears that none of the methods used in these and in previous studies gave a complete picture of what happens to aldrin and dieldrin after their contact with the soil.