Soil Properties Influencing DDT Bioactivity
1971
Peterson, J. R. | Adams, R. S. | Cutkomp, L. K.
The study was conducted to determine the important soil variables affecting the bioactivity of DDT in soils to Drosophila melanogaster Meigen. Mathematical prediction equations were derived. Failure of the bioassay technique to be generally applicable necessitated division of the 31 soil samples used into two groups. The LD₅₀ (lethal dose for 50% of the population) to D. melanogaster ranged from 43 µg DDT/g of soil in a Hubbard loamy sand subsurface sample to 790 µg/g in a Blue Earth silt loam subsurface sample. With one group of soils, a regression equation using organic carbon, fine clay, and 0.1N HCl extractable Fe contents and cation exchange capacity described 97% of the variability in LD₅₀. With a second group of soils, exhibiting much higher DDT bioactivity, a regression equation using organic carbon content and field moisture capacity described 91% of the variability. The results indicated that sorption of DDT by soil organic matter was the principal means of deactivation.
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