Reversible and Irreversible Binding of Organics to Soils and the Effect of Biodegradation

Abstract

Remediation of contaminated soil is complicated by our incomplete understanding of processes which control sorption, desorption, and biodegradation of organic contaminants associated with soil surfaces. Because of the interest in intrinsic or natural remediation, knowledge of these processes is necessary if we are to understand the risks associated with this and other soil treatment strategies. One major area of concern is the potential for release of contaminants associated with soils that are not readily extracted during soil testing. Ball and Roberts (1991) have shown that for some soils, the time scale associated with adsorption and desorption can be of the order of several years. In addition, the apparently irreversible binding of organic contaminants to soils has been observed, especially for phenolic compounds, and this binding has generally been attributed to oxidative coupling wherein phenolics are incorporated into soil humic matter by chemical (Stone 1987) or biological (Bollag 1992) mechanisms. The magnitude and ultimate fate of contaminants that are not easily extracted from soils are the main focus of this chapter.