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GUENZI W. D.; BEARD, W. E.
Soil Science: March 1981
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ABSTRACTWe evaluated the degradation of 14C ring-labeled p-chlorophenyl methyl sulfide (sulfide), -sulfoxide (sulfoxide), and -sulfone (sulfone) in soil by measuring total CO2, 14CO2, and residual 14C during a 160-day period. The amended soils (0.5, 5, and 50 ppm) were incubated at field capacity and at a constant temperature of 30°C. The amounts of 14C2 produced from ring cleavage and subsequent oxidation, expressed as the percentage, decreased as concentration increased and ranged from 5 to 17 percent. The rate of compound destruction to 14CO2 (nanograms of chemical per day) progressively increased as concentration increased, however. Residual 14C activity nearly accounted for the total activity in the 0.5− and 5-ppm treatments of the sulfoxide and sulfone, but total activity recovered from the 50-ppm treatments was only 83 percent for these same chemicals. Recovery from the sulfide treatments was much lower, which was probably due to volatilization losses during the first 10 days of incubation. Total CO2 production was not affected by soil chemical concentrations of 0.5 and 5 ppm, but was significantly reduced by the 50-ppm treatments. Degradation of chemicals (14CO2) was significantly correlated with degradation of soil organic carbon (CO2) at the two low concentrations, and this range would be representative of any potential field situation.

We evaluated the degradation of 14C ring-labeled p-chlorophenyl methyl sulfide (sulfide), -sulfoxide (sulfoxide), and -sulfone (sulfone) in soil by measuring total CO2, 14CO2, and residual 14C during a 160-day period. The amended soils (0.5, 5, and 50 ppm) were incubated at field capacity and at a constant temperature of 30°C. The amounts of 14C2 produced from ring cleavage and subsequent oxidation, expressed as the percentage, decreased as concentration increased and ranged from 5 to 17 percent. The rate of compound destruction to 14CO2 (nanograms of chemical per day) progressively increased as concentration increased, however. Residual 14C activity nearly accounted for the total activity in the 0.5− and 5-ppm treatments of the sulfoxide and sulfone, but total activity recovered from the 50-ppm treatments was only 83 percent for these same chemicals. Recovery from the sulfide treatments was much lower, which was probably due to volatilization losses during the first 10 days of incubation. Total CO2 production was not affected by soil chemical concentrations of 0.5 and 5 ppm, but was significantly reduced by the 50-ppm treatments. Degradation of chemicals (14CO2) was significantly correlated with degradation of soil organic carbon (CO2) at the two low concentrations, and this range would be representative of any potential field situation.

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