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Pharmaceuticals in Groundwater Under the Influence of On-site Septic Systems
Citation:
Glassmeyer, S., T. McCobb, E. Furlong, D. Kolpin, M. Mills, J. Shoemaker, D. LeBlanc, J. Barbaro, AND M. Belaval. Pharmaceuticals in Groundwater Under the Influence of On-site Septic Systems. SETAC North America, Portland, OR, November 14 - 18, 2021.
Impact/Purpose:
This presentation describes the results of groundwater sampling in a location switching from onsite septic to municipal wastewater. The concentrations of some pharmaceuticals in the first several rounds of sampling were found at concentrations at the same order of magnitude as that found in wastewater effluents.
Description:
Contaminants of Emerging Concern (CECs), as a class of chemicals and potential biological stressors, are difficult to measure, and can be linked to many ongoing and historic sources. One challenge with source identification and mitigation is that in many instances multiple sources contribute to contaminant loading to the aquatic system. Research has identified municipal wastewater-treatment discharges (e.g. aqueous effluents, biosolids) as important sources of CECs to the environment. Although more than 20% of households across the United States use private onsite septic systems, yet understanding and characterizing environmental exposures and corresponding environmental effects derived from such sources are lacking. Groundwater is an important resource to the Cape Cod region of Massachusetts. Cape Cod's fifteen towns rely on a sole-source aquifer for drinking water and groundwater is the primary receiver of wastewater disposal for both on-site and municipal wastewater treatment. To better manage wastewater input to the aquifer and to improve groundwater quality, over 1,400 homes in the town of Falmouth were connected to the municipal sewer system beginning in 2016. This conversion from onsite septic to a municipal sewer system provided a unique opportunity to observe potential changes occurring in groundwater quality in response to the change in the CEC source term. The results of this study will provide important information to other areas where aquifers are overlain by high densities of onsite septic systems. Groundwater samples were analyzed for over 100 chemical and microbial CECs. Maximum observed concentrations of target CECs were often found at similar (e.g. buproprion, cotinine, tramadol) or even higher (e.g., carbamazepine, fluconazole, sulfamethoxazole, sucralose) concentrations compared to that found in municipal wastewater effluent. These results clearly document onsite septic systems as another important environmental pathway for CECs.