IDENTIFICATION OF HISTORICAL PCDD F SOURCES IN NEWARK BAY ESTUARY SUBSURFACE SEDIMENTS USING POLYTOPIC VECTOR ANALYSIS AND RADIOISOTOPE DATING TECHNIQUES/

Fifty sediment cores, comprising a total of 194 individual samples, we re collected throughout the Newark Bay Estuary including the Arthur Ki ll, Rahway River, Elizabeth River, Hackensack River, Kill van Kull, an d Passaic River between November 1991 and March 1993. All samples were analyzed for polychlorinated dibenzo-p dioxins and dibenzofurans (PCD D/Fs). An additional six to ten samples were collected from each core and analyzed for the radioisotopes Pb-210 and Cs-137. The Pb-210 and C s-137 results were used to estimate sediment accumulation rates for ea ch core and approximate dates of sediment deposition for individual sa mples analyzed for PCDD/Fs. Sediment cores for which radioisotope resu lts were inadequate for radiodating were excluded from the analysis, l eaving a total of 26 cores, comprising 50 individual samples, for furt her statistical analysis. These remaining samples were grouped into th ree categories (models) based on their estimated dates of deposition. The time intervals represented by each model were 1950-1965 (model 506 5), 1970-1979 (model 7079), and 1980-1989 (model 8089). Polytopic vect or analysis (PVA) was performed separately on each model to determine the number of dominant fingerprint patterns (end members) present with in each model. PVA results indicate that the 5065 model comprises five distinct end members, while the 7079 and 8089 models comprise six dis tinct end members. Comparison of end member patterns with source-speci fic fingerprint patterns found three PCDD/F congener patterns common t o all models: combustion sources, sewage sludge sources, and sources a ssociated with polychlorinated biphenyls (PCBs). In addition, each oft he three models contained more than one sewage sludge or combustion pa ttern as well as at least one pattern that could not be identified. In many cases, the location of specific land-based sources (i.e, combine d sewer overflow (CSO) outfalls and PCB-contaminated sites) was consis tent with the identified end members. For example, the highest proport ion of the PCB source end member was present in a sample collected adj acent to a PCB-contaminated site on the lower Passaic River, and the h ighest proportions of the sewage sludge source end members were presen t in samples collected adjacent to CSO and sewage treatment plant outf alls. The combustion and sewage sludge source end members were present in relatively high proportions in nearly all samples. These results a re consistent with a recent study of surface sediments from the same l ocations, which reported that atmospheric deposition (combustion), and CSO and wastewater treatment plant discharges (sewage sludge) were th e dominant sources of PCDD/Fs to surface sediments. As with the subsur face sediments, the locations of known land-based sources are consiste nt with the end members identified in surface sediments such as the PC B-contaminated site identified in this analysis. This indicates that c ontaminants in subsurface sediments may not impact surface sediments a nd that for health risk assessment and risk management purposes, an em phasis should be placed on controlling on-going impacts to surface sed iments from municipal and industrial discharges. The results of this s tudy are consistent with recent findings reported by the U.S. Environm ental Protection Agency that combustion and incineration are the major sources of PCDD/Fs to the environment. CSOs provide a mechanism of tr ansport for combustion/incineration-related PCDD/Fs as well as those a ssociated with industries that discharge to the combined sewer system. Until combustion/incineration sources and CSO discharges are adequate ly controlled, they will remain a continuing and on-going source of PC DD/Fs to the surface sediments of the lower Passaic River. (C) 1997 El sevier Science Ltd.