Coupling biodegradation of organic chemicals to sorption and transport in soils and aquifers: Paradigms and paradoxes

Understanding sorption, biodegradation, and transport of organic chemicals in soils and aquifers is essential for predicting their fate and transport in the environment. This chapter discusses the scientific and practical issues, with a specific emphasis on biodegradation of organic chemicals in soils and aquifers. It examines the need for understanding coupling of certain key processes governing environmental behavior of pesticides and other organic chemicals in soils and aquifers; the reasons for decoupling of processes in explaining experimental observations; and the difficulties and successes encountered in developing and validating coupled-processes models and estimating the required model parameters. The major parameters needed to run the coupled-processes models can be grouped into three categories: hydrological parameters, chemical parameters, and microbiological parameters. Extensive amounts of data have been collected and indirect estimation techniques have been proposed for characterizing the hydrological and chemical parameters.