용존유기탄소의 δ13 C 분석시 고형화 전처리 방법 비교: 알칼린 과황산칼륨산화-탄산침전과 동결건조 = Comparison of Solidification Pre-treatment Methods for the Determination of δ13C of Dissolved Organic Carbon: Alkaline Persulfate Oxidation-Carbonate Precipitation vs. Freeze Drying

다국어 초록 (Multilingual Abstract)

BACKGROUND: The carbon (C) isotope ratio (δ13C) of dissolved organic C (DOC) is an indicator of water pollution source. In this study, the potential use of two pre-treatments for the δ13C analysis, alkaline persulfate oxidation coupledwith carbonate precipitation (precipitation) and freeze drying (drying), were compared to suggest a more feasible pre-treatment method.
METHODS AND RESULTS: Two reference materials with different δ13C values were used for the experiments; chemical grade glucose (-12.0±0.02‰) and pig manure compost extract (-23.3±0.04‰). In the precipitation method, themeasured δ13C values were consistently lower than the theoretically calculated values as dissolved CO2 could not be removed due to the alkaline property of the reagents and the dissolution of air CO2 into the alkaline solution. The dryingmethod also resulted inmore negative δ13C than the calculated δ13C; however, the difference was systematic (3.9±0.3‰) and therewas a strong correlation (δ 13Ccalculated=0.87×δ13Cmeasured-0.624, r2=0.98) between the calculated andmeasured δ13C. Calibration of δ13Cusingthe relationship between the calculated and themeasured δ13C values produced reliable and accurate δ13C values.
CONCLUSION:Our results suggest that the dryingmethod is more accurate pre-treatment method to minimize the influence of air CO2 compared to the precipitationmethod for the determination of δ13C of DOC.

국문 초록 (Abstract)

DOC의 δ13C은 수질 오염원 규명에 활용할 수 있는 매우유용한 지표이다. 본 연구에서는 안정성동위원소비 질량분석기(EA-SIRMS)를 이용하여 DOC의 δ13C을 분석할 때 사용하는 두 가지 전처리방법(과황산칼륨산화-SrCO3침전법과 동결건조법)의 정확도를 비교 평가하였다. 표준물질로는 글루코스(δ13C; -12.0±0.02‰)와 돈분퇴비 침출액 건조분말(δ13C; -23.3±0.04‰)을 사용하였다. 과황산칼륨산화-SrCO3침전법에서는 용액의 알칼리성에 의해 DIC 제거가 어렵고 공기 중CO2의 영향에 의해 시료가 오염되어 분석결과의 정확도가매우 낮았다. 반면, 동결건조법은 산 첨가에 의해 DIC 제거가 가능하였고, 측정값과 이론값의 상관관계가 매우 높아 실험조건별로 표준물질을 이용하여 측정값을 이론값에 근접하게 보정할 수 있는 것으로 나타났다. 따라서, EA-SIRMS를이용하여 DOC의 δ13C 분석시 동결건조법으로 시료를 전처리하면 분석결과의 정확도를 증대시킬 수 있을 것으로 판단된다.

참고문헌 (Reference)

1 Nitschelm, J. J., "Using stable isotopes to determine soil carbon input differences under ambient and elevated atmospheric CO2 conditions" 3 (3): 411-416, 1997

2 Parker, S. R., "Temporal variability in the concentration and stable carbon isotope composition of dissolved inorganic and organic carbon in two Montana, USA rivers" 16 (16): 61-84, 2010

3 Choi, W. J., "Synthetic fertilizer and livestock manure differently affect δ15N in the agricultural landscape: A review" 237 (237): 1-15, 2017

4 Van Geldern, R., "Stable carbon isotope analysis of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) in natural waters-Results from a worldwide proficiency test" 27 (27): 2099-2107, 2013

5 Yanagi, Y., "Stable carbon and nitrogen isotope analysis as a toll for inferring beef cattle feeding systems in Japan" 134 (134): 502-506, 2012

6 Tu, C. L., "Sources of dissolved organic carbon in forest soils: evidences from the differences of organic carbon concentration and isotope composition studies" 63 (63): 723-730, 2011

7 Yoo, S. H., "Soil and water qualities affected by six decades of agricultural paradigm shifts in Korea" 51 (51): 127-157, 2012

8 Ongley, E. D., "Current status of agricultural and rural non-point source pollution assessment in China" 158 (158): 1159-1168, 2010

9 Harris, D., "Continuous flow isotope ratio mass spectrometry of carbon dioxide trapped as strontium carbonate" 28 (28): 747-757, 1997

10 Lambert, T., "Carbon isotopes as tracers of dissolved organic carbon sources and water pathways in headwater catchments" 402 (402): 228-238, 2011

11 Zhou, J., "Carbon and nitrogen composition and stable isotope as potential indicators of source and fate of organic matter in the salt marsh of the Changjiang Estuary, China" 65 (65): 310-317, 2006

12 Dungait, J. A. J., "Applications of stable isotope ratio masss spectrometry in cattle dung carbon cycling studies" 24 (24): 495-500, 2010

13 Cabrera, M. L., "Alkaline persulfate oxidation for determining total nitrogen in microbial biomass extracts" 57 (57): 1007-1012, 1993

14 Sun, B., "Agricultural non-point source pollution in China: causes and mitigation measures" 41 (41): 370-379, 2012

15 최우정, "A short overview on linking annual tree ring carbon isotopes to historical changes in atmospheric environment" 한국산림과학회 8 (8): 61-66, 2012

16 Yu, K., "A persulfate oxidation method for stable isotope analysis of dissolved organic carbon and the influence of inorganic ions on the results" 392 (392): 63-68, 2015

17 Kirkels, F. M. S. A., "A novel high-temperature combustion based system for stable isotope analysis of dissolved organic carbon in aqueous samples. Ⅱ: optimization and assessment of analytical performance" 28 (28): 2574-2586, 2014

18 Amiotte-suchet, P., "13C composition of dissolved ogranic carbon in upland forested catchments of the morvan mountains (France): Influence of coniferous and deciduous vegetation" 335 (335): 354-363, 2007