ABSTRACT
Sediments are the ultimate sink for hydrophobic organic pollutants and heavy metals. This chapter assesses the direct and modeling approaches in relation to sediment-dwelling organisms. Measuring tissue residues in field-collected sediment-dwelling organisms is the most straightforward method of assessing bioaccumulation. The basic procedure for conducting laboratory bioaccumulation tests is to place appropriate test organisms into the sediment and allow the organisms to accumulate the sediment-associated pollutants. The equilibrium partitioning bioaccumulation model assumes that neutral organic pollutants obtain a thermodynamic equilibrium among infaunal organisms, solid phases, and interstitial water. Bioaccumulation can be modeled as the net result of uptake and elimination kinetics, with the uptake and elimination rates modeled as independent processes. Bioenergetic-based toxicokinetic bioaccumulation models resemble the first-order kinetic model in describing tissue residues as the balance between uptake and loss rates.
