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Caffeine in an Urbanized Estuary: Past and Present Influence of Wastewater Effluents in Boston Harbor, MA, USA
Katz, D., M. Cantwell, AND J. Sullivan. Caffeine in an Urbanized Estuary: Past and Present Influence of Wastewater Effluents in Boston Harbor, MA, USA. Society of Environmental Toxicology and Chemistry (SETAC) North America 37th Annual Meeting, Orlando, FL, November 06 - 10, 2016.
This work provides spatial information on the distribution of waterborne contaminants in an urban estuary impacted by wastewater treatment plant (WWTP) effluents using caffeine as an indicator compound. Results indicated that caffeine concentrations have significantly decreased over the last 20 years and provide insight into current contributors of wastewater contamination in Boston Harbor.
Caffeine has been identified by previous research as a potential tracer of sanitary wastewater. To further assess the utility of caffeine as a tracer of wastewater sources, samples from 25 sites throughout Boston Harbor were collected and analyzed for caffeine by LC-MS/MS. Caffeine concentrations in Boston Harbor ranged from 15 ng/L in the outer harbor to a high of 185 ng/L in the inner harbor; mean concentrations and median concentrations were 51 ng/L were 33 ng/L respectively. These data were visualized by a simple inverse distance weighting model to improve the understanding of transport and fate dynamics of wastewater derived contaminants. Elevated concentrations of caffeine in the inner harbor during the sampling period were determined to be the result of a combined sewage overflow (CSO) event as well as illicit discharge of sanitary sewage into municipal storm drains. A comparison of contemporary results to data from 1998 to 1999 shows significant reductions in caffeine levels within the harbor. For instance, concentrations were reduced by a factor of approximately 20 at the site of the former wastewater effluent discharge outfall in Boston Harbor. Lower present-day concentrations throughout the harbor were attributed to the relocation of effluent discharge from within the harbor to Massachusetts Bay, and a reduction in the number and discharge volume of CSOs. Spatial distributions of caffeine identified CSOs as the major contemporary source of contaminants to the inner harbor. These results provide additional evidence for the use of caffeine as an effective tracer of sanitary wastewater sources in urban estuaries. Furthermore, these results demonstrate the efficacy of both treated and untreated wastewater effluent reduction strategies put in place to improve the condition of Boston Harbor.