Anaerobic Conversion of DDT to DDD and Aerobic Stability of DDT in Soil

Guenzi, W. D.; Beard, W. E.

Anaerobic Conversion of DDT to DDD and Aerobic Stability of DDT in Soil

1968

Guenzi, W. D. | Beard, W. E.

¹⁴C-DDT and carrier DDT were added to nonamended and to 1% alfalfa-amended Pawnee silt loam. One set of sterile and nonsterile soil samples was incubated anaerobically, and another set was incubated aerobically. After predetermined periods of incubation, the soil samples were extracted, the extracts chromatographed on thin layer plates, and the separated radioactive DDT and decomposition products transferred into vials for quantitative determination by liquid scintillation counting. DDT was converted to DDD (TDE) in an anaerobic soil system by microorganisms; only traces of six other degradation products were detected. Amending the soil with 1% alfalfa increased the rate of conversion, and less than 1% of the applied DDT was recovered in the soil extract as the original molecule after 12 weeks of incubation. After six months of aerobic incubation, 75% of the added DDT was recovered in both the sterile and nonsterile soils. A maximum of 4% DDE and a trace of DDD was detected during the incubation period. Less than 1% of the carbon-14 in the phenyl ring of DDT was oxidized to CO₂ in the nonsterile soil. No radioactivity was found in n-hexane traps, indicating no loss of DDT in the vapor phase.

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