Seasonal nitrogen concentrations and nitrate isotopes of a New England River from 2018 to 2019

Data collection occurred in four parts during 2018 to 2019 for the Pawcatuck River: weekly collection from the Stillman and Westerly Bridges in Westerly, RI; collections were also taken seasonally from various bridges in a transect from head of the Pawcatuck River at Warden Pond to Westerly, RI; rain water was collected at UConn Avery Point - Groton, CT; and wastewater data reported by Westerly Wastewater Facility (which was corroborated in house at UConn Avery Point). Standard data collected was nutrient concentrations of nitrate, nitrite, ammonium, and phosphate. Total dissolved nitrogen, particulate nitrogen, and chlorophyll-a were also collected and measured. Our study utilized stable isotopes of nitrate and particulate nitrogen with the intent of tracking sources, cycling, and loading along the river. We focused on δ15N-NO3, δ18O-NO3, δ17O-NO3, and δ15N-PN. Through collection of rainwater at UConn Avery Point, percent atmospheric deposition of river samples based on the mass independent fractionation between δ17O and δ18O was calculated. Loading was calculated for each nutrient source based on collected data and river discharge reported from the USGS.