The adsorption and degradation behaviors of the organophosphorous insecticide chlorpyrifos in soils sampled from Ansim (AS) and Gunwi (GW) regions with different organic matter contents in Korea were investigated to predict the variable persistence of the insecticide in the soil environment. The adsorption test showed that the chlorpyrifos adsorptive capacity to the AS soil containing high organic matter content was greater than that for the GW soil. The extent of the time-dependent degradation of chlorpyrifos in the tested soils was not significantly different except at 90 days after the treatment. In the present study, a chemical-specific residue model was developed by combining Freundlich isotherm equation with first order kinetics equation. Parameters of the model were calculated using the experimental data for the adsorption and degradation of chlorpyrifos in the soils. An availability of the developed model was statistically assessed to estimate the chlorpyrifos residue in soil solutions that could be absorbed into plants. The modelled values were satisfactory, having a mean deviation of 32% from the measured data. The correlation between the modelled and measured data was acceptable, with mean coefficients of correlation (R2) of 0.89. Furthermore, the average of the residual error, known as the standard deviation of the log of residuals between measured and modelled values was low at 0.43, which corresponded to a mean factor of -1.9. Therefore, the developed model can surely be used as a critical tool to predict the subsequent plant uptake of chlorpyrifos persisted in soils, having various characteristics.

Theoretical estimation for variable persistence of chlorpyrifos in soils with different organic matters

248th National Meeting (2014)

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