Tracking nitrate sources in agricultural-urban watershed using dual stable isotope and Bayesian mixing model approach: Considering N transformation by Lagrangian sampling

Ryu, Hui-Seong; Kang, Tae-Woo; Kim, Kyung-Hyun; Nam, Taehui; Han, Yeong-un; Kim, Jihyun; Kim, Min-Seob; Lim, Hyejung; Seo, Kyungae; Lee, Kyoung-Hee; Yoon, Suk-Hee; Hwang, Seung-Hoon; Na, Eun Hye; Lee, Jung Ho

doi:10.1016/j.jenvman.2021.113693

Cited by 19 publications

(3 citation statements)

References 44 publications

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“…This study hypothesizes that nitrogen sources can be more effectively distinguished if dual δ 15 N-NH 4 and δ 15 N-NO 3 axes, rather than a single-isotope approach, are applied in complex river watersheds, especially those with sewage treatment plants. The identified manure and sewage sources based on the δ 15 N-NO 3 and δ 18 O-NO 3 values resulted in overlapping of corresponding values between some sources, leading to lack of identification accuracy [17,47,48]. Additionally, the sensitivity of δ 15 N-NH 4 to NH 4 + -N concentration is greater than that of δ 15 N-NO 3 to NO 3 − -N concentration, even when the NH 4 + -N concentration is low [16].…”

Section: Identification Of Nitrogen Sources and Contribution Using Du...mentioning

confidence: 99%

“…Nevertheless, in watersheds with complex land-use patterns, nitrogen transport processes are unclear, and the quantification of sources remains difficult [13,14]. However, approaches using stable nitrogen isotope ratios of ammonium and nitrate (δ 15 N-NH 4 and δ 15 N-NO 3 ) have garnered attention in tracking sources of nitrogen pollution [15][16][17]. The technique employing the double-use of nitrogen (δ 15 N-NO 3 ) and oxygen (δ 18 O-NO 3 ) in stable isotope analysis of nitrates using a bacterial denitrification method has been introduced [18].…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, the stable isotope ratios of nitrogen and oxygen in nitrates are determined by the nitrogen pool characteristics and chemical isotope fractionation that exist at the time of production. The natural ratios of stable nitrogen and oxygen isotopes of nitrates have been used to identify various nitrogen pollution sources such as agricultural land, forest reservoirs, and lakes [17,20,21]. This is because nitrate (NO 3 ) is the dominant form of nitrogen entering surface waters, and each nitrogen source has a distinct stable isotope ratio.…”

Section: Introductionmentioning

confidence: 99%

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A Quantitative Approach for Identifying Nitrogen Sources in Complex Yeongsan River Watershed, Republic of Korea, Based on Dual Nitrogen Isotope Ratios and Hydrological Model

Hong,

Han,

Kim

et al. 2023

Water

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Effective management of nitrate loading in complex river systems requires quantitative estimation to trace different nitrogen sources. This study aims to validate an integrated framework using soluble nitrogen isotope ratios (δ15N–NH4 and δ15N–NO3) and hydrological modeling (hydrological simulation program SPARROW) of the main stream and tributaries in the Yeongsan River to determine anthropogenic nitrogen fluxes among different land-use types in the complex river watershed. The δ15N–NH4 and δ15N–NO3 isotopic compositions varied across different land-use types (4.9 to 15.5‰ for δ15N–NH4 and −4.9 to 12.1‰ for δ15N–NO3), reflecting the different sources of nitrogen in the watershed (soil N including synthetic fertilizer N, manure N, and sewage treatment plant effluent N). We compared the soluble nitrogen isotopic compositions (δ15N–NH4 and δ15N–NO3) of the river water with various nitrogen sources (soil N, manure N, and sewage N) to assess their contribution, revealing that N from sewage treatment plant effluent as a point source was dominant during the dry season and N from forest- and soil-derived non-point sources was dominant due to intensive rainfall during the wet season. The coefficient of determination (R2) between the measured pollution load and the predicted pollution load calculated by the SPARROW model was 0.95, indicating a high correlation. In addition, the EMMA-based nitrogen contributions compared to the SPARROW-based nitrogen fluxes were similar to each other, indicating that large amounts of forest- and soil-derived N may be transported to the Yeongsan River watershed as non-point sources, along with the effect of sewage treatment plant effluent N as a point source. This study provides valuable insights for the formulation of management policies to control nitrogen inputs from point and non-point sources across different land-use types for the restoration of water quality and aquatic ecosystems in complex river systems. Given the recent escalation in human activity near aquatic environments, this framework is effective in estimating the quantitative contribution of individual anthropogenic nitrogen sources transported along riverine systems.

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