Factors influencing concentrations of polychlorinated biphenyls in organisms from an estuarine ecosystem

Abstract

Polychlorinated biphenyls (PCB's) were detected in both the abiotic and biotic components of the Brisbane River estuary. Maximum average concentrations were detected in the muscle tissue of pelican (8.2 mg kg^-1), gull (2.6 mg kg^-1) and catfish (2.1 mg kg^-1). Biomagnification was shown not to be a significant factor controlling PCB concentrations in the organisms investigated except in pelicans and gulls. In these cases, estimates of uptake from food sources indicated that biomagnification could be the major process involved. Metabolism or excretion was also found to influence the observed PCB composition of these organisms. Field and laboratory data indicated that, with some benthic organisms, sediment concentrations were the major influence on body concentrations of PCB's and a direct relationship between body concentration and the log of sediment concentration was established. Further laboratory experiments indicated that the uptake of individual PCB's was influenced primarily by two factors: the partition coefficient of n-octanol to water (p) and stereochemical effects. A direct relationship between uptake and the product of log p and the steric effect coefficient was demonstrated. Thus, maximum uptake was found with penta- and hexachlorobiphenyls, predominant in Arochlor 1254. Comparatively less uptake was found with di-, tri- and tetrachlorobiphenyls (Arochlor 1242), which have lower values for log p, and hepta- and octachlorobiphenyls, predominant in Arochlor 1260, which have lower steric effect coefficients.