Organic Pollutant Sorption in Aquatic Systems

Abstract

An understanding of sorption processes is an important key to describing pollutant fate in an aquatic system because sorption may alter significantly physical transport and chemical reactivity of pollutants. The sorption of uncharged organic chemicals to natural aquatic sorbents is dominated by “hydrophobic interactions.” For composite particulates (i.e., sediments/soils), organic matter is the primary sorbing constituent. Sorption partition coefficients, indexed to organic carbon (Koc), are relatively invariant for natural sorbents. Koc's can be estimated from other physical properties of pollutants (aqueous solubility or octanol/water partition coefficients). Hydrophilic contributions to sorption tend to occur with one or both of the following conditions: (1) High sorbate polarity; and (2) low organic carbon content of the sorbent, especially with coincident high clay content. Although a priori estimation techniques comparable to hydrophobic sorption are not presently available, hydrophilic contribution...