Page 62 - Partition & Adsorption of Organic Contaminants in Environmental Systems

Partition and Adsorption of Organic Contaminants in Environmental Systems. Cary T. Chiou
Copyright ¶ 2002 John Wiley & Sons, Inc.
ISBN: 0-471-23325-0

5 Contaminant Partition and

Bioconcentration

5.1 INTRODUCTION

The partition of organic compounds in a partially miscible solvent–water
system has been an important subject in chemistry as the basis for solvent
extraction of solutes from water. The application of partition coefficients to
biochemical systems began about a century ago with Meyer (1899) and
Overton (1901), who showed that the relative narcotic activities of drugs were
well correlated with their oil–water partition coefficients. The usefulness of the
partition coefficient as a system parameter for assessing the biochemical activ-
ity of an organic compound or a drug has been greatly extended by the work
of Fujita et al. (1964), Hansch and Fujita (1964), Hansch (1969), Leo and
Hansch (1971), and Leo et al. (1971). Leo and Hansch (1971) reviewed the
partition characteristics of organic compounds in a variety of solvent–water
systems and for practical reasons considered the octanol–water system to
be the most appropriate reference for assessing the relative lipophilicity
of organic solutes with biological components. Hansch (1969) showed, for
example, that the partition coefficients of organic solutes between protein
and water could be correlated successfully with their octanol–water partition
coefficients, thus providing an assessment of the binding of small organic
molecules with biological macromolecules.
The utility of partition coefficients to estimate the distribution of organic
contaminants in environmental systems has meanwhile become increasingly
evident since the 1970s. This development stemmed primarily from the obser-
vations that the potential of an organic contaminant to concentrate from water
into aquatic organisms (e.g., fish) may be correlated successfully with its
octanol–water partition coefficient (Neely et al., 1974; Lu and Metcalf, 1975;
Chiou et al., 1977; Könemann and van Leeuwen, 1980; Oliver and Nimii, 1983,
Banerjee et al., 1984; Chiou, 1985). Similar empirical correlations with
octanol–water partition coefficients were also found for soil/sediment–water
distribution coefficients of selected groups of organic contaminants (Chiou et
al., 1979; Karickhoff et al., 1979; Kenaga and Goring, 1980; Means et al., 1980;
Briggs, 1981; Schwarzenbach and Westall, 1981). Although the contaminant
distribution between water and natural organic substrates may often be more
complicated than a simple partition, these results manifest that an important
driving force for contaminant distribution in natural aquatic systems is con-
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