Stable isotope on the evaluation of water quality in the presence of WWTPs in rivers

Lee, Jaewoong; Park, Taejin; Kim, Min-seob; Kim, Jongmin; Lee, Seunghyun; Lee, Su Kyuong; Lee, Young-Sun; Lee, Won-seok; Yu, Soonju; Rhew, Doughee

Stable isotope on the evaluation of water quality in the presence of WWTPs in rivers

2016

We investigated the distribution of nitrogen compounds in Han River as well as two tributaries of Tancheon and Jungrangcheon. Particularly, we observed the significant releases of NH₄ ⁺-N from effluent of wastewater treatment plants (WWTPs) in two tributaries that has resulted in the increases of ammonium nitrogen (NH₄ ⁺-N) in Han River as well as in Tancheon and Jungrangcheon. Due to the increases of NH₄ ⁺-N in two tributaries, the larger distribution of δ¹⁵N-NH₄ ⁺ was observed than those of δ¹⁵N-NO₃ ⁻ in downstream. We calculated the contribution rate of ammonium nitrogen and nitrate nitrogen from effluent to downstream according to the results of stable isotope. The contribution rates of δ¹⁵N-NH₄ ⁺ from effluent to downstream were significant that ranged between 53 and 100 % in Tancheon and between 27 and 100 % in Jungrangcheon. While the contribution of δ¹⁵N-NO₃ ⁻ was not significant in Tancheon, it was occasionally observed in Jungrangcheon. These results demonstrated that WWTPs are the major sources of NH₄ ⁺-N in two tributaries, which caused the distinguishable stable isotope of δ¹⁵N-NH₄ ⁺. Therefore, the stable isotope of δ¹⁵N-NH₄ ⁺ could be a useful parameter or tracer for the evaluation of NH₄-N released from WWTPs in rivers.

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