ABSTRACT
Bioaccumulation of organic chemicals by fishes is a function of the properties of the chemical, the physiological characteristics of the animal and the physical and biological characteristics of the receiving environment. Most low molecular weight organics in bleached kraft mill effluents (BKMEs), such as chlorophenolics and aliphatics, have log KOW values in the 1 to 5 range and are accumulated mainly via uptake over the gills. Bioaccumulation of these compounds can be predicted with bioconcentration factors (BCF) if dissolved concentrations in water are known, although BCFs may be overestimated because of biotransformation. Very hydrophobic BKME components such as polychlorinated dioxins/furans (PCDD/Fs) are not only dissolved but are associated with particles and dissolved organic carbon in effluent and in receiving waters. PCDD/Fs are accumulated by fish mainly via the diet. Bioaccumulation of PCDD/Fs can be predicted from biota-sediment accumulation factors or with food chain models that include both water-borne and dietary pathways of accumulation. Sediment-water disequilibrium and food chain effects need to be taken into account when using BSAFs and food chain modeling to predict bioaccumulation.
