Fate of PCB congeners in an industrial harbor of Lake Michigan.

We have quantified the release of polychlorinated biphenyls (PCBs) from Indiana Harbor and Ship Canal (IHSC) to Lake Michigan and the atmosphere. Navigational dredging is planned for this system, and there is concern that dredging will result in releases of PCBs. We have analyzed greater than 158 PCBs in surficial sediment, water, suspended particles, and air. We predicted the release of PCBs from sediments to water and from water to air. To quantify the level of confidence in our calculations, we used a Monte Carlo simulation for each congener flux. We determined that 4 +/- 0.05 kg of summation operatorPCBs were released from the sediment to the water and 7 +/- 0.1 kg of summation operatorPCBs were volatilized from the water to the air annually. We measured input from the upstream regions of the canal system of 45.0 kg yr(-1) and export to Lake Michigan of 43.9 kg yr(-1). The summation operatorPCBs mass balance accounts for nearly all the PCB inputs and losses to the navigational regions. The congener profiles in sediment, water, and air support our determination that the contaminated sediment is a major source of PCBs into the water and air above it. We have shown that the system is currently a significant source of PCBs to the air and to Lake Michigan, even under quiescent conditions.