Factors Affecting the Volatilization of Insecticidal Residues from Soils

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Abstract
Laboratory and field studies showed that vapors toxic to both vinegar flies (Drosophila melanogaster Meigen) and house flies (Musca domestica L.) were given off from aldrin, heptachlor-phorate-, lindane-, heptachlore-poxide-, and dieldrin-treated soils. No evidence of volatization was obtained from soils treated with DDT, Sevin (1-naphthyl N-methylcarba-mate), malathion, and parathion. An increase in the rate of aldrin volatization from the soil resulted from increases in: Insecticide concentration in the soil; soil moisture; relative humidity of air passing over the soil; soil temperature; and rate of air movement over the surface of the soil. A decrease in the rate of aldrin volatization was noted in dry soils containing increasing amounts of clay and organic matter, and in wet soils containing increasing amounts of organic matter. The amount of soil in a given volume (bulk density) had no effect on the rate of aldrin volatilization. In laboratory tests conducted over intervals of 5 to 7 days, it was possible to account for 90% to 96% of the aldrin initially applied to three soil types (Quartz sand, Plainfield sand and Miami silt loam). It was found that 55% to 80% of the initially applied aldrin was present as aldrin 5 to 7 days after application, while only small amounts were converted to dieldrin. From 16% to 38% of the applied aldrin volatilized from the soil. Initially, the rate of aldrin volatilization was rapid, but over longer periods of time the insecticide became "bound" to the soil and volatilization decreased 1 day after insecticidal application to a constant rate which varied with the soil type.