ABSTRACT
The role of chemical speciation in metal bioavailability can be interpreted in many different ways. The term speciation has been used for many varied meanings. Bioavailability is even more contentious; different fields have precise but different definitions for it. The link between speciation and bioavailability has long been recognized and many earlier texts have summarized some of the important aspects (Allen et al 1980, Florence 1982, Langston and Bryan 1984, Bernhard et al. 1986, Bruemmer et al. 1986, Allen 1993, Luoma 1995, Tack and Verloo 1995, Allen and Hansen 1996). This chapter interprets bioavailability within the context of ecotoxicological risk assessment (as opposed to anthropocentric health assessment) as seen by the author. For human-based risk assessment, readers are referred to Chapter 1. Various approaches for chemical speciation will be explored in more detail, from simple separation in a contaminant pool to the free ion activity model.
