• 한국물환경학회지
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• 제35권6호
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• pp.510-519
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• 2019

The 'Stable Isotope Analysis in R' (SIAR), one of the Bayesian mixing models for stable isotopes, has been proven to be useful for source apportionment of nitrates in rivers. In this study, the contribution ratios of nitrate sources were quantified by using the SIAR based on nitrogen and oxygen stable isotope measurements in the Yeongsan River. From the measurements, it was found that the values of δ¹⁵N-NO₃ and δ¹⁸O-NO₃ ranged from -8.2 ‰ to +13.4 ‰ and from +2.2 ‰ to +9.8 ‰, respectively. We further analyzed the contribution ratios of the five nitrate sources by using the SIAR. From the modeling results, the main nitrate source was found to be soil N (29.3 %), followed by sewage (26.7 %), manure (19.6 %), chemical fertilizer (17.9 %) and precipitation (6.3 %). From the results, it was found that the anthropogenic sources, i.e., sewage, manure and chemical fertilizer contribute 64.2% of the total nitrate inflow from the watershed. Due to the significant correlation of δ¹⁵N-NO₃ and lnNO₃^- in this study, the fractionation factors reflecting the biogeochemical processes of stable isotope ratios could be directly obtained. This may make the contribution ratios obtained in this study more precise. The fractionation factors were identified as +3.64 ± 0.91 ‰ for δ¹⁵N-NO₃ (p<0.01) and -5.67 ± 1.73 ‰ for δ¹⁸O-NO₃(p<0.01), respectively, and were applied in using the SIAR. The study showed that the stable isotope method using the SIAR could be applied to quantitatively calculate the contribution ratios of nitrate sources in the Yeongsan River.

• 한국지하수토양환경학회지:지하수토양환경
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• 제27권2호
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• pp.87-98
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• 2022

This study aims to prepare a technical protocol for identifying the source of nitrate in water using nitrogen (δ¹⁵N) and oxygen (δ¹⁸O) stable isotope ratios. The technical processes for nitrate sources identification are composed of site investigation, sample collection and analysis, isotope analysis, source identification using isotope characteristics, and source apportionment for multiple potential sources with the Bayesian isotope mixing model. Characteristics of various nitrate potential sources are reviewed, and their typical ranges of δ¹⁵N and δ¹⁸O are comparatively analyzed and summarized. This study also summarizes the current knowledge on the dual-isotope approach and how to correlate the field-relevant information such as land use and hydrochemical data to the nitrate source identification.

• 생태와환경
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• 제49권4호
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• pp.279-288
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• 2016

탄소와 질소 안정동위원소비를 이용한 먹이망 구조 해석 기법은 수생태계 연구에서 폭 넓게 활용되고 있으며, 먹이원의 정량적 기여율을 분석하는 믹싱모델에 적용될 수 있다. 본 연구에서는 Bayesian 모델을 이용한 믹싱모델의 적용이 가능한 통계 패키지(R, SIAR package)의 사용방법을 제시하고, 사용 예로 저수지 및 메소코즘 배양조에서의 동물플랑크톤과 먹이원의 탄소, 질소 안정동위원소비를 이용한 섭식 성향 분석 방법 및 결과를 제시하였다. 분석 결과, 국내 저수지 및 대형하천 등에서 주로 우점하는 Daphnia galeata는 소형의 POM (<$50{\mu}m$)을 주로 섭식하는 것으로 나타나, 부영양화된 환경에서 녹조 발생시 먹이로의 활용이 용이하지 않은 것으로 나타났다. 논 생태계 등에서 빈번히 출현하는 패충류의 경우 D. galeata와 유사한 섭식 성향을 나타내었다. 반면 습지 등에서 주로 출현하는 Simocephalus vetulus의 경우, 부착성 POM이 아닌 부유성 POM을 주로 섭식하며 Microcystis를 포함하는 대형의 POM (>$50{\mu}m$)을 섭식하는 것으로 분석되었다.