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RISS 인기검색어
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- 저자 : 정현미 ( Jongwoo Choi ) (검색결과 3 건)
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암모늄 확산법을 이용한 암모늄 질소 안정동위원소 분석법
김민섭 ( Min-seob Kim ),임보라 ( Bo-ra Lim ),박시영 ( Si-yeong Park ),유은진 ( Eunjin Yoo ),정현미 ( Hyen-mi Chung ),최종우 ( Jongwoo Choi ) 한국환경농학회 2020 한국환경농학회 학술대회집 Vol.2020 No.-
In this study, we introduce the method for measuring <sup>15</sup>N-NH<sub>4</sub><sup>+</sup> using an ammonium diffusion technique. The advantage of this method is that it is broadly applicable to all types of water and it allows measurements in samples with lower ammonium concentrations than has previously been possible. The NH<sub>4</sub><sup>+</sup> is converted to NH<sub>3</sub> with pH〈11 condition and then it is trapped in a filter package with ammonium sulfate. During different incubation time of 1, 2, 3, 4, 5, 6, 7, 9, 12 and 14 days, measured <sup>15</sup>N-NH<sub>4</sub><sup>+</sup> values of samples reacted after 7 days yielded the most consistent results with certified values. To evaluate a success of the method developed in this study, two international standards, IAEA-N1 (δ<sup>15</sup>N = +0.4‰) and IAEA-N2 (δ<sup>15</sup>N = +20.3‰) were used. Measured their δ<sup>15</sup>N values were +0.4 ± 0.3‰ (n=10) for IAEA-N1 and +20.3 ± 0.2‰ (n=10) for IAEA-N2, respectively, in excellent agreement with recommended values within the error. The method developed in this study will be useful tool for the identification of nitrogen source in aquatic ecosystem.
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탈질법을 이용한 질산험의 질소 및 산소 안정동위원소비 분석법 소개
임보라 ( Bo-ra Lim ),김민섭 ( Min-seob Kim ),박시영 ( Si-yeong Park ),유은진 ( Eunjin Yoo ),정현미 ( Hyen-mi Chung ),최종우 ( Jongwoo Choi ) 한국환경농학회 2020 한국환경농학회 학술대회집 Vol.2020 No.-
Nitrogen loading from domestic, agricultural and industrial sources can lead to excessive growth of macrophytes or phytoplankton in aquatic environment. Many studies have used stable isotope ratios to identify anthropogenic nitrogen in aquatic systems as a useful method for studying nitrogen cycle. In this study to evaluate the precision and accuracy of denitrification bacteria method (Pseudomonas chlororaphis ssp. aureofaciens(ATCC® 13985)), three reference (I AEA-NO-3 (Potassium nitrate KNO<sub>3</sub>), USGS34(Potassium nitrate KNO<sub>3</sub>), USGS35(Sodium nitrate KNO3)) were analyzed 5 times repeatedly. Measured the δ<sup>15</sup>N-NO<sub>3</sub> and δ<sup>18</sup>O-NO<sub>3</sub> values of IAEA-NO-3, USGS34 and USGS35 were δ<sup>15</sup>N:4.7±0.1‰ δ<sup>18</sup>O:25.6±0.5‰, δ<sup>15</sup>N:-1.8±0.1‰ δ<sup>18</sup>O:-27.8±0.4‰, and δ<sup>15</sup>N:2.7±0.2‰ δ<sup>18</sup>O:57.5±0.7‰, respectively, which are within recommended values of analytical uncertainties. Also, we investigated isotope values of potential nitrogen source (soil, synthetic fertilizer and organic-animal manures) and temporal patterns of δ<sup>15</sup>N-NO3 and δ<sup>18</sup>O-NO<sub>3</sub> values in groundwater samples during from May to December. δ<sup>15</sup>N-NO3 and δ<sup>18</sup>O-NO<sub>3</sub> values are enriched in December suggesting that organic-animal manures should be one of the main N sources in those areas. The current study clarifies the reliability of denitrification bacteria method and the usefulness of stable isotopic techniques to trace the anthropogenic nitrogen source in freshwater ecosystem.
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TC/TN-IRMS를 이용한 수질시료 내 총 유기탄소 안정동위원소 분석법 소개
박시영 ( Si-yeong Park ),김민섭 ( Min-seob Kim ),임보라 ( Bo-ra Lim ),윤숙희 ( Suk-hee Yoon ),유은진 ( Hyen-mi Chung ),정현미 ( Jongwoo Choi ),최종우 한국환경농학회 2020 한국환경농학회 학술대회집 Vol.2020 No.-
The measurement of stable isotope ratios on total organic carbon (TOC) has long posed analytical problems and limited the use of this powerful tracer in biogeochemical studies in aquatic systems. Here, we provide a detailed description of a successful coupling of a custom-modified total organic carbon and nitrogen analyzer (Elementar, ISO TOC Cube) to an isotope-ratio mass spectrometer (Isoprime precision, CF-IRMS). The method is based on the wet oxidation of up to 20 mL aqueous sample in a closed reactor, produced CO<sub>2</sub> is carried over a water trap and purification column in a stream of He and introduced into the IRMS via a conventional open-split interface, enabling both quantification and δ<sup>13</sup>C analysis. Typical repeatability of δ<sup>13</sup>C analyses on TOC in this setup is in the order of 0.3‰ or better, comparable to that obtained in a more conventional elemental analyzer-IRMS setup. Typical overall system blank values for TOC analysis are in the order of 1 ㎍ C. Analytical conditions (reaction time, reagent concentrations) were optimized for samples, so that a single method can handle all types of environmental TOC samples. To evaluate a success of the method developed in this study, two international standards, IAEA-600 (δ<sup>13</sup>C = -27.7‰) and IAEA-CO-8 (δ<sup>13</sup>C = -5.7‰) were used. Measured their δ<sup>13</sup>C values were -27.7 ± 0.3‰ (n=100) for IAEA-600 and -5.7 ± 0.4‰ (n=100) for IAEA-CO-8, respectively, in excellent agreement with recommended values within the error. The method developed in this study will help researcher studying carbon cycle and tracing sources of TOC in the aquatic environment.
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