Experiments and modeling to quantify irreversibility of pesticide sorption-desorption in soil

Abstract

Pesticide sorption behavior is a complex process. The importance of extremely slow retention and release has superseded the notion that sorption of pesticides to soil is an instantaneous and reversible process. A fraction of sorbed pesticide is also often reported to bind irreversibly to the soil matrix. Irreversible sorption has potentially significant implications for reducing pesticide mobility and bioavailability. However, an accepted experimental method with the ability to quantify irreversible sorption does not exist due to procedural difficulties in identifying slowly reversible and irreversible fractions relevant at the field scale. Use of isotopes, generally 14C, is a promising means of quantifying irreversible sorption and providing crucial parameters and data for pesticide fate modeling.