The fundamental sorption and desorption reactions between selected chlorinated hydrocarbon pesticides and clay minerals were established. The effects of several important environmental factors, including pH, temperature, salt (NaCl) concentration, and organic content, on the sorption and desorption reactions were also ascertained. Results obtained reveal that organochlorine pesticides are rapidly adsorbed by clays and also retained strongly after adsorption. Only small fractions of the adsorbed pesticides can be desorbed. The environmental factors of pH, temperature and salt content appear to exert no significant effect on the sorption and desorption reactions. The organic pollutants present in the water phase also bear no effect on the reactions. However, the organic humus present in the sediment phase is able to enhance the pesticide adsorption because chlorinated hydrocarbon pesticides are adsorbed in much greater quantities by organic humus than by clay minerals. Based on the study it seems promising that the sludge materials generated by waste treatment plant can be used as the pesticide carrier or diluent in future agricultural applications. (Author)