Mobility of pesticides and their hydrolysis metabolites in soil

The soil thin layer chromatography technique was employed to assess the mobility of 21 chemicals (6 insecticides, 4 herbicides, and 11 of their hydrolysis metabolites) in 6 different soils. The hydrolysis products of the four studied organophosphorus insecticides were significantly more mobile than their parent compounds, but the metabolites of carbamates, s triazines and phenoxy alkanoic acids were less mobile than their parent compounds. For the chemicals for which significant effects of soil variables were observed, greater levels of organic matter, clay, cation exchange capacity and water holding capacity (at one‐third bar) lowered the mobility Soil pH significantly affected mobility of many of the chemicals studied, with increased mobility in soils with higher pH values. Both water solubility and octanol/water partition coefficient ( K ow ) significantly correlated with the mobility of the chemicals studied, however, K ow was found to be the better predictor of mobility No direct relationship existed between the pK a of the chemicals and their mobility