Fugacity-Based Model of PCB Bioaccumulation in Complex Aquatic Food Webs

Abstract

A fugacity-based model is developed to simulate the phenomena of bioconcentration and biomagnification of organic contaminants in complex food webs in aquatic systems comprising contaminated water and sediment. The food web consists of N classes of organisms, which may feed on all organisms including their own class, and in which each organism may experience chemical uptake from benthic or pelagic food organisms and water with clearance by respiration, egestion, and metabolism. The expressions reduce to a single equation involving an N × N matrix of food preference parameters that is readily solved to give concentrations and fluxes throughout the food web. The model is applied illustratively to bioaccumulation of PCB congeners in Lake Ontario yielding results generally within a factor of 3 of measured values. This approach quantifies the roles of exchange with water, food uptake, and food web structure as determinants of bioaccumulation in aquatic systems and has the potential to be extended to treat broader food webs including terrestrial and avian organisms.