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Title: Fate and Distribution of the Octyl- and Nonylphenol Ethoxylates and Some Carboxylated Transformation Products in the Back River, Maryland

Author
item LOYO-ROSALES, JORGE - UNIV OF CA, BERKLEY
item Rice, Clifford
item TORRENTS, ALBA - UNIV OF MD, COLLEGE PARK

Submitted to: Journal of Environmental Monitoring
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/6/2009
Publication Date: 11/27/2009
Citation: Loyo-Rosales, J.E., Rice, C., Torrents, A. 2009. Fate and Distribution of the Octyl- and Nonylphenol Ethoxylates and Some Carboxylated Transformation Products in the Back River, Maryland. Journal of Environmental Monitoring. 12:614-621.

Interpretive Summary: The concentrations of nonylphenol (NP), octylphenol (OP), their ethoxylates (NP0-16EO and OP0-5EO respectively) and some of their carboxylated derivatives (NP1-2EC and OP1EC quantitatively; NP3-4EC and OP2EC qualitatively) were evaluated in water samples from the Back River, MD, a sub-estuary of the Chesapeake Bay that receives effluent from Back River wastewater treatment plant. The most abundant of the alkylphenolic compounds (APEs) were the carboxylates (APECs, > 95% on mass basis), followed by NP in September and October, and NP1-2EO in March. NP concentrations found in this study, 0.087 – 0.69 µg/L, were below acute toxicity thresholds, and generally below recently proposed water quality criteria by the US EPA; although in March, concentrations can be close to 40% of the chronic exposure limit (1.7 µg/L) for saltwater. Total NPE concentrations in the estuary seemed to vary in accordance to the concentrations in the WWTP effluent, especially in the case of the APECs. However, a closer analysis of the data using a simple steady-state model of the Back River suggested that in the fall sampling events, when rain occurred, the ethoxylates present in the particulate matter might have originated in the river’s tributaries rather than the WWTP.

Technical Abstract: The Back River is a sub-estuary of the Chesapeake Bay that receives effluent from a wastewater treatment plant (WWTP) and urban runoff from the metropolitan area of Baltimore, MD. In order to study the fate of the alkylphenol ethoxylates (APEOs) and their transformation products, including those that have been found to be weakly estrogenic, the concentrations of nonylphenol and octylphenol ethoxylates (NP0-16EO and OP0-5EO respectively), nonylphenol (NP), octylphenol (OP), and the carboxylated derivatives NP1-2EC and OP1EC were measured in water samples collected in the Back River and the WWTP effluent in September and October 2004, and in March 2005. In all sampling events, the most abundant of the alkylphenolic compounds (APEs) were the carboxylates (APECs, > 95%), followed by NP in September and October, and NP1-2EO in March. NP concentrations found in this study, 0.087 – 0.69 µg/L, were below acute toxicity thresholds, and generally below the U.S. EPA water quality criteria; although in March concentrations were approximately 30 to 50% of the chronic exposure limit (1.4 µg/L) for saltwater. Total NPE concentrations in the estuary seemed to be a function of the concentrations in the WWTP effluent, especially in the case of the APECs. However, a closer analysis of the data suggested that in the fall sampling events, when rain occurred, the long-chain ethoxylates present in the particulate matter originated in the river’s tributaries carrying urban runoff and not in the WWTP. Fitting these data to a simple steady-state model provided additional incite into the environmental fate of these compounds.