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Selected Pharmaceuticals Entering an Estuary: Concentrations, Temporal Trends, Partitioning and Fluxes
Citation:
Cantwell, M., D. Katz, J. Sullivan, K. Ho, R. Burgess, AND M. Cashman. Selected Pharmaceuticals Entering an Estuary: Concentrations, Temporal Trends, Partitioning and Fluxes. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY. Society of Environmental Toxicology and Chemistry, Pensacola, FL, 35(11):2665-2673, (2016).
Impact/Purpose:
The long-term usage of pharmaceutical compounds has resulted in their presence at elevated levels in the waters of developed nations. Following use, active pharmaceutical ingredients (APIs) enter the environment with their primary route of entry through domestic wastewater treatment plant discharges. Pharmaceuticals has been identified as a contaminant of emerging concern, with little known about their fate and effects, particularly in estuarine environments. This manuscript details a long-term sampling study specifically conducted so that the temporal trends of the APIs could be elucidated in order to make an accurate assessment of their potential exposure risk. A total of 15 pharmaceuticals comprising 8 classes of compounds were selected and measured in this study based on their high volume use or high frequency of detection in freshwater systems. The range of concentrations in the SPM and dissolved phase for each of the APIs over the course of the study illustrates the temporal variability associated with urbanized rivers that receive high proportions of domestic WWTP effluents. Both Kds and Kocs were derived for the studied APIs over the course of 1 year, normalizing to the ƒoc in the SPM (Koc) reduced the variability in the Kds, indicating the importance of organic matter for regulating sorption of APIs. The long-term results of this study report the range of variability in partitioning that has not been observed to date in prior field or laboratory studies. Further, The temporal trends of the APIs provides information needed to begin to assess and understand the risk of chronic exposure of these pharmaceuticals to marine aquatic life via the water column and support development of aquatic life criteria.
Description:
In many coastal watersheds and ecosystems, rivers discharging to estuaries receive waters from domestic wastewater-treatment plants resulting in the release and distribution of pharmaceuticals to the marine environment. In the present study, 15 active pharmaceutical ingredients were measured regularly over 1 yr in the dissolved and particulate phases as they entered Narragansett Bay from the Pawtuxet River in Cranston (Rhode Island, USA). Of the active pharmaceutical ingredients measured, 14 were consistently present in the dissolved phase, with concentrations ranging from below detection to >310 ng/L, whereas 8 were present in the particulate phase (0.2–18 ng/g). Partition coefficients (Kds and KOCs) were determined, and organic carbon normalization reduced variability associated with Kds for the active pharmaceutical ingredients evaluated. Flux estimates based on river flow were calculated for both dissolved and particulate-phase active pharmaceutical ingredients, with particulate fluxes being low (1–12 g/yr) and dissolved fluxes of active pharmaceutical ingredients being 155 g/yr to 11 600 g/yr. Results indicate that the pharmaceuticals measured in the present study reside primarily in the dissolved phase and thus are likely bioavailable on entering the estuarine waters of Narragansett Bay. This long-term temporal study provides important information on seasonal and annual dynamics of pharmaceuticals in an urban estuarine watershed.
