Predicting the Environmental Partitioning of Organic Contaminants and their Transfer to Biota

Abstract

This chapter examines the partitioning behaviour of chemicals in aquatic ecosystems. We first outline this behaviour in qualitative terms by identifying the phases or compartments of interest, and the extent to which organic chemicals can establish concentration differences between these compartments. Reasons are suggested for this partitioning behaviour. In many respects the partitioning phenomena can be explained by simple physical chemical principles, thus we digress to examine these principles and especially the role of fundamental physical chemical properties in determining partitioning characteristics. There is a compelling incentive to establish these principles because the large number of organic chemicals encountered in aquatic systems renders a chemical by chemical assessment virtually impossible. It is preferable to seek out the underlying determinants of partitioning and develop chemical structure-property-partitioning relationships thus enabling the behaviour of one chemical to be inferred from that of another. It transpires that there are two methods of characterizing this partitioning behaviour; the conventional partition coefficient approach, and the more recent and novel fugacity approach. Ultimately, these two approaches give identical results. Both are illustrated in this chapter.