Modeling the Fate and Transport of Organic Contaminants in Lake St. Clair

Abstract

Despite the rapid hydraulic turnover time of Lake St. Clair, inputs of organic contaminants to the lake are a cause for concern because of their potential long-term storage in the lake's surficial sediments. In order to understand and predict the transport and fate of organic contaminants in Lake St. Clair, a multisegment, contaminant mass balance model was developed. The model was calibrated and tested against four data sets that describe the behavior of the conservative chloride ion, and against two data sets that describe the fate and distribution of sediment-bound cesium-137. Model applications included simulations of octachlorostyrene (OCS) and polychlorinated biphenyl (PCB) dynamics in the lake. The model predicted that during 1971-83, 3.8 MT of OCS entered the lake, 2.8 MT were flushed from the system, 0.8 MT were lost due to biological degradation and volatilization, and 0.2 MT remained in the system. The model also predicted that during 1970–74, 3.4 MT of PCB entered the lake, 2.1 MT were flushed from the system, 2.2 MT were lost due to biological degradation and volatilization, and the system mass of PCB decreased from 1.9 to 1.0 MT.