Distribution of Kepone in the James River Estuary

Abstract

An analysis is presented defining the distribution of an organic chemical in the water and bed of an estuarine system. The present structure of the model is a tidally averaged two‐dimensional (longitudinal‐vertical) main channel interacting with lateral embayments. The water column, segmented into two layers to incorporate the typical estuarine circulation, interacts with a bed which is also segmented into two layers, an active transport layer and a deeper stationary bed. Adsorption‐desorption kinetics are included which, in the case of Kepone distribution of the James River, are assumed to be at equilibrium. Both steady‐state as well as time‐variable conditions are analyzed to calibrate the model to reproduce presently observed concentrations of Kepone. A procedure of analysis to address the problem of organic chemicals in estuaries has been structured. The procedure involves a series of analytic and computational steps, relating to the fluid transport, the solids distribution, and the concentrations of the organic chemical in the water and the bed. The model has been applied to analyze the temporal and spatial distribution of Kepone in the James River under both constant and time‐variable freshwater flow conditions. Using actual hydrology and an assumed mass rate of input of Kepone, the concentration was calculated for a 10‐yr period of production, comparing well to observed values in the water and bed. Projections are presented to estimate the mass contained in the bed and that discharged to Chesapeake Bay.