Identification of Pollutants Sources of Water Supply using Nitrogen (δ15N) and Oxygen (δ18O) Stable Isotope Ratio in Nitrate

Abstract

In this study, according to determination of nitrogen (δN) and oxygen (δO) from nitrate (NO 3 ) in water for 2 years, 2016-2017, Gunwi, Korea, the origin of pollutants in supply water could be found. The sampling sites are including 6 points, Donggok, Yonga, Janggok1 and 2, reservoir of dam and Ingak temple around Gunwi Dam, Korea. The water samples were determined NO 3 -N using Ion Chromatography and Nitrogen (δN) and Oxygen (δO) stable isotope ratio in nitrate and isotope ratio mass spectrometry, respectively. The standard deviation of determined standard materials is less than 0.2‰ for δN AIR and 0.2‰ for δO VSMOW in water. The origin of the supply water pollution was analyzed through the correlation between the values of δN and δO in nitrate. The values indicated that these sources were originated sewage and livestock manure in the Dam. The dominant contribution of water pollutants was calculated about 50% from Donggok location in this study. In addition, the location of Yonga where has the small inflow rate also constantly contributed to the Dam.