Modeling Cadmium Fate at Superfund Site: Impact of Bioturbation

Abstract

A model of cadmium fate in the Foundry Cove Superfund site is calibrated to the postloading period from 1972 to 1989. Bioturbation (i.e. benthic mixing) of sediment cadmium is calculated to be primarily responsible for the slow decline in surface cadmium over this period. Such mixing increases the flux of cadmium from the cove by about an order of magnitude over the case of no mixing. Hindcasting previous cadmium exposure from consumption of contaminated blue crabs indicates an increased exposure of about 25 times acceptable levels during the peak loading period of 1965–70. Simulation of remedial controls indicates that if no action is taken, cadmium concentrations will continue to be at elevated levels at least to the year 2012. Capping of the inner cove with clean sand over an impermeable barrier (equivalent to “removal” of sediment cadmium), however, results in an immediate and constant decrease in cadmium to background levels.