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TEMPORAL TRENDS OF AROCLOR 1268 IN THE TAUNTON RIVER ESTUARY: EVIDENCE OF EARLY PRODUCTION, USE AND RELEASE TO THE ENVIRONMENT
Citation:
CANTWELL, M. G., J. KING, AND R. M. BURGESS. TEMPORAL TRENDS OF AROCLOR 1268 IN THE TAUNTON RIVER ESTUARY: EVIDENCE OF EARLY PRODUCTION, USE AND RELEASE TO THE ENVIRONMENT. MARINE POLLUTION BULLETIN. Elsevier Science Ltd, New York, NY, 52(9):1105-1111, (2006).
Impact/Purpose:
To help explain the presence of previously reported high levels of PCB congeners in sediments of the Lower Taunton River.
Description:
Sediment cores were collected at three sites from the Lower Taunton River in Narragansett Bay, MA, dated and examined for PCBs. At each site, PCBs first appear in the sediment cores at depths corresponding to 1929 based on a combination of radiometric and anthropogenic dating proxies. In the early to mid-1940s, PCB concentrations rose rapidly in each core with a simultaneous increase in the proportion of hepta to decachlorobiphenyl congeners present. The congener distribution pattern was identified as Aroclor 1268, a highly chlorinated technical PCB mixture. Accumulation of Aroclor 1268 continued at each of the sites with concentrations peaking by the late 1950s. One coring site located adjacent to a former industrial facility had much higher PCB concentrations than the others, suggesting that this location was the source of PCBs to the Taunton River. Temporal trends in the cores show that Aroclor 1268 discharge was discontinued in the late 1950s, and by the early 1970s, a wide distribution of congeners were present in all cores. However, at two of the three coring locations, elevated concentrations of the congeners associated with Aroclor 1268 are still present in surficial sediments (0-5cm), accounting for 34% and 55% of the total measured PCB, respectively. This finding indicates that physical processes in the river such as sediment resuspension are maintaining relic contaminants in the active sediment layer, with continued lateral transport of sediment-bound contaminants occurring long after their discharge. The early discharge of Aroclor 1268 combined with transport processes explains the presence of previously reported high levels of PCB congeners 206 and 209 present in surficial sediments of the Lower Taunton River.