PESTICIDE ADSORlrrION IN A SOIL-WATER SYSTEM IN THE PRF~ENCE OF SURFACTANTS

In the present work changes in the adsorption of four 14C-labelled pesticides-diazinon, acephate, atrazine and ethofumesate- ona sandy loam soil, induced by application of anionic, cationic and nonionic suffactants-tetradecyitrimethylammonium bro ide (TDTMA), sodium dodecyl sulphate (SDS) and polyoxyethylene sorhitanmonooleate (Tween 80)-, were determined using a batch equilibrium method. Three concentrations of each surfactant were used: lower, equal to or higher than the critical micellar concentration. The increases or decreases in the values of the Freundlieh constant K for adsorption of the different pesticides by soil in the experiments revealed that the bebaviour of pesticides in soil-water systems with micelle-forming surfactants mainly depends on the degree of hydrophohicity of the pesticide and the type of surfactant, as well as on the concentration f surfactant in the system. Copyright © 1996 Elsevier Science Lt