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RECONSTRUCTION OF CONTAMINANT TRENDS IN A SALT WEDGE ESTUARY WITH SEDIMENT CORES DATED USING A MULTIPLE PROXY APPROACH
Citation:
CANTWELL, M. G., J. W. KING, R. M. BURGESS, AND P. G. APPLEBY. RECONSTRUCTION OF CONTAMINANT TRENDS IN A SALT WEDGE ESTUARY WITH SEDIMENT CORES DATED USING A MULTIPLE PROXY APPROACH. MARINE ENVIRONMENTAL RESEARCH. Elsevier Science Ltd, New York, NY, 64(2):225-246, (2007).
Impact/Purpose:
to reconstruct spatial and temporal trends of pollution in an estuary
Description:
The Taunton River is a partially mixed tidal estuary in southeastern Massachusetts (USA) which has received significant contaminant inputs, yet little information exists on the history of discharge and the subsequent fate of these contaminants. Three sediment cores taken along a transect were analyzed, reconstructing the spatial and temporal trends of pollution in the estuary. A combination of radiometric dating, contaminant markers, and storm layers from major hurricanes were used to establish age models and sediment accumulation rates. Age estimates obtained from the different dating methods compared well, resulting in an accurate time-line of contaminant release to the estuary. Polycyclic aromatic hydrocarbons (PAHs) were present in one core at depths corresponding to the early 1860s, earlier than previously established dates of introduction. Temporal and spatial trends of Cr, Cu, Hg and Pb indicated multiple sources of input to the river whose contributions changed over time. Polychlorinated biphenyls (PCBs) were present in each of the cores from the 1930s onward, with elevated levels still present in surficial sediments at several sites. A unique organic compound which was produced locally was used as a tracer to track contaminant transport in the river. Tracer data indicates that contaminants are still being transported and deposited to surficial sediments at high concentrations well after their discharge. This reconstruction demonstrates the utility of using multiple dating proxies where often the sole use of radiometric dating techniques is not an option and provides insights into the fate of contaminants discharged decades ago but continue to represent environmental risks.