Time-integrated, flux-based monitoring using semipermeable membrane devices to estimate the contribution of industrial facilities to regional polychlorinated biphenyl budgets

Passive monitoring of polychlorinated biphenyls (PCB) using semipermeable m embrane devices (SPMD) was employed to evaluate the contribution of point a nd nonpoint sources to the Bur of PCB in a drainage system encompassing thr ee U.S. Department of Energy (U.S. DOE) industrial and research facilities in eastern Tennessee, USA. Polychlorinated biphenyls concentrations were hi ghest at outfalls containing process waste from the DOE industrial faciliti es. The significance of these releases was evaluated by calculating the PCB flux (mass per unit time) at different monitoring locations. The Bur was c alculated from the time-integrated estimates of the aqueous concentrations of PCB and estimates of the volumetric flow rates of discharges and receivi ng streams during the deployment period. The DOE discharges accounted for m ost of the flux of PCB entering the Clinch River from the DOE drainage area s, but these sources constituted only 10% of the flux in the Clinch River a bout the DOE sources. Principal components analysis was helpful in attribut ing sources of PCB. In a stream receiving multiple inputs of PCB, congener profiles from upstream sources and discrete discharges were consistent with a mixture of those congener profiles in the downstream receiving water. In another stream with a single upstream source of PCB, changes in PCB Aux an d congener profiles suggested an apparent steady-state distribution between dissolved PCB and PCB adsorbed to organic matter on the streambed. The flu x of dissolved PCB along different stream reaches reflected changes in the sediment organic content. Subtle alterations in congener profiles moving do wnstream suggested preferential desorption of less chlorinated congeners an d sorption of mon highly chlorinated congeners to sediment. Time-integrated flux-based monitoring can be useful across a range of spatial scales for e valuating the significance of point and nonpoint contaminant sources and ca n help identify and prioritize feasible remedial alternatives.