Effects of Climate Change and Pharmaceuticals and Personal Care Products on Nitrogen Reduction Efforts in the Long Island Sound Watershed

Abstract

Nutrient enrichment of surface waters can lead to harmful algae blooms and hypoxic events in estuaries which is a concern in the New England region. Long Island Sound is an estuary bordered by Long Island, NY, and Connecticut with a history of nitrogen enrichment from wastewater and stormwater runoff. My paper focuses on the impacts of climate change and pharmaceuticals and personal care products (PPCPs) on nitrogen reduction efforts in the Long Island Sound watershed. To understand these potential impacts, I searched for scientific papers from major repositories using questions regarding the relationships between precipitation, surface runoff, CSO events, nitrogen loading, and the potential synergetic effects of climate change, plus the impact of PPCPs on bacterial nitrogen reduction. I then conducted a literature review and analysis of the articles to establish their findings on these relationships. Afterwards, I conducted a case study on four urban Connecticut districts with CSOs, analyzing their urban cover, precipitation, and CSO events to substantiate the relationships. The analysis of the literature established that surface runoff from precipitation on impervious surfaces is a main contributor to CSO events and subsequent nitrogen pollution. Furthermore, climate change is predicted to increase heavy precipitation, subsequently increasing stormwater and CSO volumes, and the concentration of conveyed pollutants. Results from the case study indicate an increase in the intensity of impervious surfaces and an increase in the average monthly rainfall (0.17 inches; March to September) in the studied districts. Also, a statistically significant relationship between rainfall and CSO events was found for the districts of Bridgeport and Norwich. Lastly, common PPCPs found in wastewater such as antimicrobials can have an inhibitory effect on bacterial nitrification and denitrification processes. Mitigation strategies to address stormwater runoff in urban areas should be targeted and applied at different spatial scales for the greatest effect. More study is needed using direct measurements of rainfall, stormwater, and CSO discharges to better understand their relationship and conveyance of nitrogen to surface waters. Moreover, direct testing for common PPCPs in wastewater is needed to ascertain current concentrations and their potential effects on nitrogen reduction during wastewater treatment.