PT15 Contaminated Harbour and River Sediment
Exhibit Hall
8:00 AM - Tuesday
(PT255) Reconstructing historical inputs of contaminants to the lower Taunton River using sediment cores along a transect.
Cantwell, M1, 2, King, J2, Burgess, R1, 1 US EPA NHEERL, Narragansett, RI, USA2 Graduate School of Oceanography, Narragansett, RI, USA
ABSTRACT- Estuaries have long been considered to be sinks for contaminants released as a consequence of anthropogenic activities. The Taunton River is a partially mixed tidal estuary in southeastern Massachusetts (U.S.A.) which has received significant chemical inputs since the Industrial Revolution, yet little information exists on the history of these discharges, and the subsequent fate of contaminants within the estuary. Embedded in the sediment is an archive of the pollutants accumulating over time. In this study, analysis of sediment cores enabled vertical profiles to be developed reconstructing the spatial and temporal trends of pollution in the Taunton River estuary. In this presentation, preliminary results of chemical analysis of sediment cores taken from along a transect in the Taunton River are presented. Polycyclic aromatic hydrocarbons (PAHs) were the first contaminants to appear in the cores at depths corresponding to the early 1880s. Heavy metals increased from background levels well before the 20th century, with Cr, Cu, Hg, Pb and Zn each exhibiting different temporal trends. Polychlorinated biphenyls (PCBs) are present in each of the cores from the 1930s onward, with changing congener patterns upcore, suggesting a major change in PCB composition over time. Using known contaminant introduction dates to establish sediment accumulation rates compared well with estimates from 210Pb and 137Cs dating techniques, demonstrating their utility as sediment dating proxies. A phenolic antioxidant compound with a known source and date of introduction to the river was used as a tracer to measure contaminant movement over time. Spatial data analysis reveals many of the contaminants present in the river emanated from a single point-source upstream, with subsequent redistribution along the transect by sediment transport processes. This type of reconstruction analysis provides insights on the behavior and fate of contaminants discharged years and decades ago but which continue to represent environmental risks.
Key words: contaminant remobilization, contaminated sediment, historical reconstruction, sediment cores