Polychlorinated Biphenyl Source Identification in Fish Tissue Using a Multivariate Statistical Evaluation of Congeners and Stable Isotope Ratio Mass Spectrometry

Polychlorinated biphenyls (PCBs) were commercially produced mixtures primarily utilized as dielectric fluids in the electrical industry. However, due to their stability, they were widely used in many other applications. Although production of PCBs ceased in the 1970\u27s, they continue to be a contaminant in the environment due to their widespread use, their recalcitrant behavior, and their proposed toxicological effects. In 2008, a routine environmental investigation of an abandoned, concrete-lined pool at a Department of Defense (DoD) training facility in Williamsburg, Virginia led to the discovery of a PCB release from the facility into an adjacent reservoir. A forensic study was performed to determine if other PCB sources were present and to evaluate if the contamination in the fish could be traced to specific sources. This research required the analysis of soils, sediments, and fish, and the subsequent fingerprinting of PCB profiles in each media. Polytopic vector analysis (PVA) was utilized to estimate the number of end-members (sources) that contributed to contamination in different species of fish, the relative contributions of key congeners in each species, and the mixing proportion of estimated end-members in each sample. Calculated end-member profiles from the PVA were compared to known concentrations of PCBs found in several sediment locations. Following the PVA evaluations, carbon and chlorine compound specific isotope analysis (CSIA) of several sediment and fish tissue samples was performed using a novel approach in an effort to further confirm the initial conclusions from the PVA. Despite weathering processes, which significantly changed the PCB congener profiles from the respective sources, results of the PVA and the general profiles of PCBs in sediments from different locations confirmed that while the PCB release from the DoD facility has impacted fish in the reservoir, there were other sources of PCB present in sediments and fish. Reference locations far removed from the Navy release showed the highest concentrations in sediments but did not show a prevalent signature in fish tissue. The isotopic data support the PVA conclusions that a source signature consistent with the Navy release was the prevalent signature in the fish, but the data also show the presence of other sources