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Spatial Distribution of the Emerging Contaminant Triclosan in Sediments and Water of an Urbanized Estuary: Greenwich Bay, Rhode Island, USA
Citation:
Katz, D., M. Cantwell, J. Sullivan, M. Perron, R. Burgess, K. Ho, AND M. Charpentier. Spatial Distribution of the Emerging Contaminant Triclosan in Sediments and Water of an Urbanized Estuary: Greenwich Bay, Rhode Island, USA. Presented at SETAC North America 33rd Annual Meeting, Long Beach, CA, November 11 - 15, 2012.
Impact/Purpose:
Triclosan is an antibacterial additive used in the formulation of a variety of consumer and personal care products. Triclosan’s primary route of entry to the environment is through domestic wastewater treatment plant discharges. Triclosan has been identified as a contaminant of emerging concern, with little known about its fate and effects, particularly in estuarine environments. This contribution describes the spatial distribution of Triclosan in surficial sediments and a sediment core collected from a semi-enclosed urbanized estuarine embayment located within Narragansett Bay, Rhode Island on the Atlantic Coast of the United States. Surficial sediments show a decrease in Triclosan concentrations with increasing distance from the waste water treatment plant. Previous sediment core records typically show increasing Triclosan concentrations over the last several decades, however, sediment core data from this site shows a decrease in Triclosan over approximately the last 20 years. The decrease in Triclosan upcore also corresponds to a contemporaneous decrease of a chemical tracer associated with local commercial production of Triclosan. An estimate of the spatial distribution of Triclosan was produced using ordinary kriging, and these results combined with waste water treatment effluent data indicate Triclosan is being advected into Greenwich Bay from outside sources. The information in this article will be useful for scientists and regulators involved with assessing the environmental risk associated with the use of Triclosan and similar chemicals used in consumer products which enter the environment via waste water treatment effluent.
Description:
The use of personal care products (PCPs) has resulted in the release and accumulation of a diverse assemblage of emerging chemicals in the environment. Many PCPs incorporate triclosan (TCS), an antimicrobial compound, within their formulations and as a result, TCS is frequently present in wastewater treatment plant (WWTP) effluents. Many wastewater outfalls discharge directly or indirectly into the marine environment along the coastline of the United States. Continuous discharge of wastewater effluent has resulted in the accumulation of PCP components such as TCS in coastal and estuarine sediments. This study investigated the factors controlling the accumulation and spatial distribution of TCS within the sediments of a small urbanized embayment with a single domestic WWTP. Dissolved TCS in the water column was measured at several sites (n=14) and found to range between 0.5 and 8.0 ng L-1 with higher concentrations further from the WWTP outfall. Sediment TCS was measured at sites throughout the bay and associated coves and higher concentrations were found in the coves (n=36) where sediments were enriched in organic carbon. A bay-wide sediment TCS budget was determined by ordinary kriging of measured values. Annual accumulation rates exceeded the calculated annual discharge of TCS from the local WWTP, indicating contribution of TCS from at least one previously unidentified source. Further investigation using sediment cores and a chemical tracer revealed that advective processes are likely responsible for transporting the excess TCS into the embayment. Results suggest a significant fraction of the TCS in Greenwich Bay originated from upper Narragansett Bay, which receives effluent from several large WWTPs and contains TCS-contaminated sediments from past manufacturing activities. This study demonstrates an approach to better understand the factors affecting the distribution emerging contaminants within estuarine systems.