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Observations of Wickford Harbor, RI Before and During Non-Point Source Nutrient Reductions
Citation:
Schwartz, M., A. Oczkowski, Alana Hanson, S. Balint, AND Rick McKinney. Observations of Wickford Harbor, RI Before and During Non-Point Source Nutrient Reductions. NEERS Spring Meeting 2023, Brooklyn, NY, April 27 - 29, 2023.
Impact/Purpose:
Non-point sources of pollution are hard to identify making them difficult to manage and monitor. Furthermore, it is difficult to predict when and how an ecosystem will respond to changes in non-point source pollution. This preliminary data shows how embayments are responding before and during the changeover of local homes and businesses from septic to sewage, reducing non-point nitrogen inputs.
Description:
Septic inputs are considered to be the primary source of nutrients in some shallow embayments in Wickford Harbor, RI. In 2017, the town of North Kingstown installed a sewer line to decrease non-point source nitrogen (N) contributions, and in the years since then local shops, restaurants, and some homes have tied in. In 2018 we began monthly monitoring of nutrients, stable isotopes, and water quality parameters to characterize the embayments before and during reductions in septic inputs. Fecal coliform counts averaged 65.4 CFU/100ml with a maximum of 588.0 CFU/100ml, indicating the presence of septic effluent. Particulate organic matter analyzed for N stable isotopes has an average delta15N of 7.9 permil, consistent with sewage influence, but seasonal decreases to < 5 permil suggest complex N dynamics. Definitive responses to the non-point N reductions have not yet been detected but we expected slow responses. We will continue to monitor so that we can draw conclusions about the reduction of non-point source pollution in the future.
