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Herbstritt B, Wengeler L, Orlowski N. Coping with spectral interferences when measuring water stable isotopes of vegetables. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2024; 38:e9907. [PMID: 39234849 DOI: 10.1002/rcm.9907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 08/20/2024] [Accepted: 08/21/2024] [Indexed: 09/06/2024]
Abstract
RATIONALE Laser-based analyzers are widely used in ecohydrology to analyze plant water isotopic compositions (δ18O and δ2H). The suitability of three different water extraction and isotope equilibration techniques was compared. We examined whether co-extracted volatile organic compounds (VOCs) affect laser-based isotope measurements and used the instrument's spectral parameters to post-correct for interfering VOCs. METHODS Cryogenic vacuum extraction, vapor headspace equilibration in bags, and vapor equilibration in situ probes were used to extract liquid water or water vapor for laser-based isotope analysis (cavity ring-down spectrometry, CRDS). Isotope data were calibrated by standards for each method separately. Spectral parameters of the instrument, appropriate to identify spectral interferences with MeOH and CH4, were identified and used for post-correction. Differences between the three methods and between the origins of the vegetables were identified by statistical tests. RESULTS VOCs were found in various amounts for the three different methods. They were co-extracted or co-equilibrated during the different extraction or equilibration methods. Correlation coefficients of isotope data and "CH4" (spectral parameter) were 0.99 or better; however, slopes for δ18O were similar on different instrument types but different for δ2H. Our correction approach improved results and inter-comparability of the methods considerably without knowing the chemical composition of the plant sap. CONCLUSIONS All three methods were sensitive enough to distinguish and resolve differences in natural abundance. Data quality was improved by the "CH4 correction" approach but could probably be optimized by a plant species-specific correction. Standardized tools for contaminant removal or post-correction applications from manufacturers, in particular for vapor-mode analysis, are still needed.
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Affiliation(s)
- Barbara Herbstritt
- Faculty of Environment and Natural Resources, University of Freiburg, Freiburg im Breisgau, Germany
| | - Lena Wengeler
- Faculty of Environment and Natural Resources, University of Freiburg, Freiburg im Breisgau, Germany
| | - Natalie Orlowski
- Faculty of Environment and Natural Resources, University of Freiburg, Freiburg im Breisgau, Germany
- Institute of Soil Science and Site Ecology, TU Dresden, Tharandt, Germany
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Orlowski N, Rinderer M, Dubbert M, Ceperley N, Hrachowitz M, Gessler A, Rothfuss Y, Sprenger M, Heidbüchel I, Kübert A, Beyer M, Zuecco G, McCarter C. Challenges in studying water fluxes within the soil-plant-atmosphere continuum: A tracer-based perspective on pathways to progress. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 881:163510. [PMID: 37059146 DOI: 10.1016/j.scitotenv.2023.163510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 04/04/2023] [Accepted: 04/10/2023] [Indexed: 06/01/2023]
Abstract
Tracing and quantifying water fluxes in the hydrological cycle is crucial for understanding the current state of ecohydrological systems and their vulnerability to environmental change. Especially the interface between ecosystems and the atmosphere that is strongly mediated by plants is important to meaningfully describe ecohydrological system functioning. Many of the dynamic interactions generated by water fluxes between soil, plant and the atmosphere are not well understood, which is partly due to a lack of interdisciplinary research. This opinion paper reflects the outcome of a discussion among hydrologists, plant ecophysiologists and soil scientists on open questions and new opportunities for collaborative research on the topic "water fluxes in the soil-plant-atmosphere continuum" especially focusing on environmental and artificial tracers. We emphasize the need for a multi-scale experimental approach, where a hypothesis is tested at multiple spatial scales and under diverse environmental conditions to better describe the small-scale processes (i.e., causes) that lead to large-scale patterns of ecosystem functioning (i.e., consequences). Novel in-situ, high-frequency measurement techniques offer the opportunity to sample data at a high spatial and temporal resolution needed to understand the underlying processes. We advocate for a combination of long-term natural abundance measurements and event-based approaches. Multiple environmental and artificial tracers, such as stable isotopes, and a suite of experimental and analytical approaches should be combined to complement information gained by different methods. Virtual experiments using process-based models should be used to inform sampling campaigns and field experiments, e.g., to improve experimental designs and to simulate experimental outcomes. On the other hand, experimental data are a pre-requisite to improve our currently incomplete models. Interdisciplinary collaboration will help to overcome research gaps that overlap across different earth system science fields and help to generate a more holistic view of water fluxes between soil, plant and atmosphere in diverse ecosystems.
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Affiliation(s)
- Natalie Orlowski
- Hydrology, Faculty of Environment and Natural Resources, University of Freiburg, Freiburg im Breisgau, Germany.
| | - Michael Rinderer
- Hydrology, Faculty of Environment and Natural Resources, University of Freiburg, Freiburg im Breisgau, Germany; Geo7 AG, Bern, Switzerland
| | - Maren Dubbert
- Isotope Biogeochemistry and Gasfluxes, ZALF, Müncheberg, Germany
| | | | - Markus Hrachowitz
- Department of Water Management, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Stevinweg 1, 2628CN Delft, Netherlands
| | - Arthur Gessler
- Forest Dynamics, Swiss Federal Research Institute WSL, Birmensdorf, Switzerland; Institute of Terrestrial Ecosystems, ETH Zurich, Zurich, Switzerland
| | - Youri Rothfuss
- Institute of Bio- and Geosciences, Agrosphere (IBG-3), Forschungszentrum Jülich GmbH, Jülich, Germany; Terra Teaching and Research Centre, University of Liège, Gembloux, Belgium
| | - Matthias Sprenger
- Earth and Environmental Sciences at the Lawrence Berkeley National Laboratory, Berkeley, USA
| | - Ingo Heidbüchel
- Hydrological Modelling, University of Bayreuth, Bayreuth, Germany; Hydrogeology, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany
| | - Angelika Kübert
- Institute for Atmospheric and Earth System Research (INAR), University of Helsinki, Helsinki, Finland
| | - Matthias Beyer
- Institute for Geoecology, Technische Universität Braunschweig, Braunschweig, Germany
| | - Giulia Zuecco
- Department of Land, Environment, Agriculture and Forestry, University of Padova, Legnaro, Italy; Department of Chemical Sciences, University of Padova, Padova, Italy
| | - Colin McCarter
- Department of Geography, Department of Biology and Chemistry, Nipissing University, North Bay, Ontario, Canada
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Shin WJ, Jung YY, Choi M, Choi SH, Choi HB, Lee KS, Bong YS, Song H, Koh DC. National-scale investigation of dual nitrate isotopes and chloride ion in South Korea: Nitrate source apportionment for stream water. ENVIRONMENTAL RESEARCH 2023; 228:115873. [PMID: 37062482 DOI: 10.1016/j.envres.2023.115873] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 04/05/2023] [Accepted: 04/09/2023] [Indexed: 05/16/2023]
Abstract
Nitrate sources in surface water have been identified using dual-isotope compositions of nitrate with various tools to efficiently manage the water quality at the local scale. Correlation between Cl and NO3 has also been used to identify NO3. In this study, we assess the reliability of the dual-isotope approach and Cl in terms of nitrate source apportionment. To this end, we collected stream water samples throughout South Korea to estimate nitrate sources in streams and determine whether the land-use pattern was closely related to nitrate sources. The δ15N-NO3 ranging from -1.3 to 14.8‰ showed a spatial distribution that was lower in mountain ranges (<7‰) than plain areas (>8‰). The Cl concentration in this national-scale distribution was also assessed. The relationship between the proportion of Cl and δ15N-NO3 classifies nitrate sources into areas characterized by three land-use patterns: (1) agricultural and business areas, (2) forests in highlands, and (3) lowland forests, of which (1) had proportions of Cl >50%, while (2) and (3) were <50%. The samples in (3) showed δ15N-NO3 values > 6‰, similar to those of (1). Deuterium excess of samples was negatively correlated (R2 = 0.53) with δ15N-NO3, accounting for the fact that δ15N-NO3 reflected land-use patterns. Samples were dominantly affected by agriculture-derived sources and domestic sewage showed NO3/Cl of <0.4 and δ15N-NO3 of >6‰. These results suggest that nitrate source apportionment should be comprehensively evaluated considering the dual-isotope approach, land-use patterns, and Cl proportions.
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Affiliation(s)
- Woo-Jin Shin
- Research Center for Geochronology and Isotope Analysis, Korea Basic Science Institute, Cheongju-si, Chungbuk, 28119, Republic of Korea.
| | - Youn-Young Jung
- Research Center for Geochronology and Isotope Analysis, Korea Basic Science Institute, Cheongju-si, Chungbuk, 28119, Republic of Korea
| | - Moojin Choi
- Research Center for Geochronology and Isotope Analysis, Korea Basic Science Institute, Cheongju-si, Chungbuk, 28119, Republic of Korea
| | - Seung-Hyun Choi
- Research Center for Geochronology and Isotope Analysis, Korea Basic Science Institute, Cheongju-si, Chungbuk, 28119, Republic of Korea
| | - Hye-Bin Choi
- Research Center for Geochronology and Isotope Analysis, Korea Basic Science Institute, Cheongju-si, Chungbuk, 28119, Republic of Korea; Department of Science Education, Ewha Womans University, Seoul, 03760, Republic of Korea; Healthcare & Spa Industry Promotion Agency, Chungnam, 31471, Republic of Korea
| | - Kwang-Sik Lee
- Research Center for Geochronology and Isotope Analysis, Korea Basic Science Institute, Cheongju-si, Chungbuk, 28119, Republic of Korea; Graduate School of Analytical Science and Technology, Chungnam National University, Daejeon, 34134, Republic of Korea
| | - Yeon-Sik Bong
- Center for Research Equipment, Korea Basic Science Institute, Cheongju-si, Chungbuk, 28119, Republic of Korea
| | - Hyeongseok Song
- Graduate School of Analytical Science and Technology, Chungnam National University, Daejeon, 34134, Republic of Korea; Chromatography and Mass Spectrometry Division, Thermo Fisher Scientific, Seoul, 06349, Republic of Korea
| | - Dong-Chan Koh
- Korea Institute of Geoscience and Mineral Resources, Daejeon, 34132, Republic of Korea; University of Science and Technology, Daejeon 34113, Republic of Korea
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Zhang J, Xu Z. Vacuum extraction of high-salinity water for the determination of oxygen and hydrogen isotopic compositions using cavity ring-down spectroscopy. Microchem J 2023. [DOI: 10.1016/j.microc.2023.108678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2023]
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Jung YY, Shin WJ, Seo KH, Koh DC, Ko KS, Lee KS. Spatial distributions of oxygen and hydrogen isotopes in multi-level groundwater across South Korea: A case study of mountainous regions. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 812:151428. [PMID: 34742991 DOI: 10.1016/j.scitotenv.2021.151428] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 10/18/2021] [Accepted: 10/31/2021] [Indexed: 06/13/2023]
Abstract
This study presents the spatial distributions of stable isotopes for groundwater according to well depth and spring water across South Korea, using an interpolation model to provide baseline information for hydrological studies. In total, 888 groundwater and 108 spring water samples were collected across South Korea; their oxygen and hydrogen isotopic compositions (δ18O and δ2H) were analyzed. δ18O and δ2H values biased toward the summer local meteoric water line and low d-excess values indicate that summer precipitation is important for groundwater recharge. The δ18O and δ2H values for groundwater and spring water decrease progressively from the southwest to the northeast on the Korean Peninsula. Based on eight hydrological regions, the average δ18O values of groundwater and spring water are negatively correlated with latitude, but they are positively correlated with temperature. This result indicates that the spatial distributions of groundwater isotopic values in South Korea are significantly influenced by latitude and altitude effects associated with the movement of the North Pacific air mass in summer. Spring waters showed a negative correlation between δ18O and d-excess, with more depleted 18O values than groundwater, indicating that local recharge and flow within mountainous areas is dominant. Considering that the correlation in multi-level groundwater located in northern regions is similar to that of spring water, the contribution of regional groundwater flow, which is recharged in mountainous areas, is considered to be higher in the northern regions. The spatial distribution of δ18O in groundwater gradually approached the spatial distribution of spring water with increasing well depth, indicating that the contribution of regional groundwater flow may be greater in deep groundwater. Our results provide estimates for data-poor regions, supporting the investigation of links between groundwater and other hydrological factors.
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Affiliation(s)
- Youn-Young Jung
- Korea Basic Science Institute, Chungbuk 28119, Republic of Korea
| | - Woo-Jin Shin
- Korea Basic Science Institute, Chungbuk 28119, Republic of Korea
| | - Kyung-Hen Seo
- Korea Environment Corporation, Incheon 22689, Republic of Korea
| | - Dong-Chan Koh
- Korea Institute of Geoscience and Mineral Resources, Daejeon 34132, Republic of Korea; University of Science and Technology, Daejeon 34113, Republic of Korea
| | - Kyung-Seok Ko
- Korea Institute of Geoscience and Mineral Resources, Daejeon 34132, Republic of Korea
| | - Kwang-Sik Lee
- Korea Basic Science Institute, Chungbuk 28119, Republic of Korea.
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Cui J, Lide T, Yu W. Organic contamination in online laser-based plant stem and leaf water isotope measurements for pre-extracted samples. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2021; 57:262-270. [PMID: 33594914 DOI: 10.1080/10256016.2021.1883010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 12/17/2020] [Indexed: 06/12/2023]
Abstract
Water stable isotopes have been widely used as natural tracers to investigate soil-plant-atmosphere interactions. Recent developments in induction module cavity ring-down spectroscopy (IM-CRDS) have made it possible to rapidly complete isotope analyses, and to combust co-extracted organic compounds at the same time. However, the agreement between IM-CRDS and isotope ratio mass spectrometry (IRMS) analyses has generally been poor and was primarily attributable to spectral interference of IM-CRDS. Here we evaluated the impacts of organic contamination on the isotope ratios using IM-CRDS with two different methods. No spectral interference was observed for solid samples measured directly by IM-CRDS, whereas clear organic contamination occurred in isotope analyses for pre-extracted plant stem and leaf samples. Our results demonstrate that IM-CRDS can fully combust co-extracted organic compounds by in-line oxidation in the direct measurement of solid samples, although this may not guarantee that the IM-CRDS can obtain better isotopic data than IRMS. It may be risky to evaluate the performance of IM-CRDS by measuring pre-extracted water samples because cryogenic vacuum distillation is likely to introduce extra organic compounds, which may not be fully removed during subsequent IM-CRDS measurement. In addition, spectral variables are useful for post-processing corrections.
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Affiliation(s)
- Jiangpeng Cui
- Key Laboratory of Tibetan Plateau Environment Change and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, People's Republic of China
- Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences, Peking University, Beijing, People's Republic of China
| | - Tian Lide
- Key Laboratory of Tibetan Plateau Environment Change and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, People's Republic of China
- CAS Centre for Excellence in Tibetan Plateau Earth Sciences, Beijing, People's Republic of China
- Institute of International Rivers and Eco-Security, Yunnan University, Kunming, People's Republic of China
| | - Wusheng Yu
- Key Laboratory of Tibetan Plateau Environment Change and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, People's Republic of China
- CAS Centre for Excellence in Tibetan Plateau Earth Sciences, Beijing, People's Republic of China
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7
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Dew-induced transpiration suppression impacts the water and isotope balances of Colocasia leaves. Oecologia 2018; 187:1041-1051. [DOI: 10.1007/s00442-018-4199-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 06/05/2018] [Indexed: 10/28/2022]
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8
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Gerlein-Safdi C, Gauthier PPG, Sinkler CJ, Caylor KK. Leaf water 18 O and 2 H maps show directional enrichment discrepancy in Colocasia esculenta. PLANT, CELL & ENVIRONMENT 2017; 40:2095-2108. [PMID: 28658718 DOI: 10.1111/pce.13002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Revised: 05/31/2017] [Accepted: 06/02/2017] [Indexed: 06/07/2023]
Abstract
Spatial patterns of leaf water isotopes are challenging to predict because of the intricate link between vein and lamina water. Many models have attempted to predict these patterns, but to date, most have focused on monocots with parallel veins. These provide a simple system to study, but do not represent the majority of plant species. Here, a new protocol is developed using a Picarro induction module coupled to a cavity ringdown spectrometer to obtain maps of the leaf water isotopes (18 O and 2 H). The technique is applied to Colocasia esculenta leaves. The results are compared with isotope ratio mass spectrometry. In C. esculenta, a large enrichment in the radial direction is observed, but not in the longitudinal direction. The string-of-lakes model fails to predict the observed patterns, while the Farquhar-Gan model is more successful, especially when enrichment is accounted for along the radial direction. Our results show that reticulate-veined leaves experience a larger enrichment along the axis of the secondary veins than along the midrib. We hypothesize that this is due to the lower major/minor vein ratio that leads to longer pathways between major veins and sites of evaporation.
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Affiliation(s)
- Cynthia Gerlein-Safdi
- Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ, 08544, USA
| | - Paul P G Gauthier
- Department of Geosciences, Princeton University, Princeton, NJ, 08544, USA
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Craig James Sinkler
- Department of Geological, Environmental, and Marine Sciences, Rider University, Lawrenceville, NJ, 08648, USA
- EarthRes Group Inc., Pipersville, PA, 18947, USA
| | - Kelly Krispin Caylor
- Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ, 08544, USA
- Department of Geography, UC Santa Barbara, Santa Barbara, CA, 93106, USA
- Bren School of Environmental Science and Management, UC Santa Barbara, Santa Barbara, CA, 93106, USA
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Cui J, Tian L, Gerlein-Safdi C, Qu D. The influence of memory, sample size effects, and filter paper material on online laser-based plant and soil water isotope measurements. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2017; 31:509-522. [PMID: 28072488 DOI: 10.1002/rcm.7824] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 01/06/2017] [Accepted: 01/07/2017] [Indexed: 06/06/2023]
Abstract
RATIONALE The recent development of isotope ratio infrared spectroscopy (IRIS) was quickly followed by the addition of online extraction and analysis systems, making it faster and easier to measure soil and plant water isotopes. However, memory and sample size effects limit the efficiency and accuracy of these new setups. In response, this study presents a scheme dedicated to estimating and eliminating these two effects. METHODS Memory effect was determined by injecting two standard waters alternately. Each standard was injected nine times in a row and analyzed using induction module cavity ring-down spectroscopy (IM-CRDS). Memory coefficients were calculated using a new "multistage jump" algorithm. Sample size effects were evaluated by injecting water volumes ranging from 1 μL to 6 μL. Finally, the influence of cellulose filter paper on the isotopic measurements, the memory, and the sample size effect was evaluated by comparing it with glass filter paper. RESULTS Memory effects were detected for both δ18 O and δ2 H values, with the latter being stronger. Isotopic differences between replicates of the same plant or soil sample showed a clear decrease after memory correction. A small water volume effect was found only when the injected water volume was larger than 3 μL. However, while the correction method performed well for laboratory-made samples, it did not for field samples, due to the heterogeneity of the isotopic composition of the samples. Stronger memory and water volume effects were found for cellulose filter paper. CONCLUSIONS The memory coefficients and the water volume-isotope relationship improved the consistency and accuracy of both laboratory and field data. Our results indicate that cellulose filter paper may not be a suitable medium to measure standard waters and evaluate memory and water volume effects. Finally, a detailed correction and calibration protocol is suggested, along with notes on best practices to obtain good-quality IM-CRDS data. Copyright © 2017 John Wiley & Sons, Ltd.
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Affiliation(s)
- Jiangpeng Cui
- Key Laboratory of Tibetan Plateau Environment Change and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Lide Tian
- Key Laboratory of Tibetan Plateau Environment Change and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, 100101, China
- CAS Centre for Excellence in Tibetan Plateau Earth Sciences, Beijing, 100101, China
| | - Cynthia Gerlein-Safdi
- Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ, 08540, USA
| | - Dongmei Qu
- Key Laboratory of Tibetan Plateau Environment Change and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, 100101, China
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Johnson JE, Hamann L, Dettman DL, Kim-Hak D, Leavitt SW, Monson RK, Papuga SA. Performance of induction module cavity ring-down spectroscopy (IM-CRDS) for measuring δ 18 O and δ 2 H values of soil, stem, and leaf waters. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2017; 31:547-560. [PMID: 28010033 DOI: 10.1002/rcm.7813] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2016] [Revised: 12/19/2016] [Accepted: 12/20/2016] [Indexed: 06/06/2023]
Abstract
RATIONALE Induction module cavity ring-down spectroscopy (IM-CRDS) has been proposed as a rapid and cost-effective alternative to cryogenic vacuum distillation (CVD) and isotope ratio mass spectrometry (IRMS) for the measurement of δ18 O and δ2 H values in matrix-bound waters. In the current study, we characterized the performance of IM-CRDS relative to CVD and IRMS and investigated the mechanisms responsible for differences between the methods. METHODS We collected a set of 75 soil, stem, and leaf water samples, and measured the δ18 O and δ2 H values of each sample with four techniques: CVD and IRMS, CVD and CRDS, CVD and IM-CRDS, and IM-CRDS alone. We then calculated the isotopic errors for each of the three CRDS methods relative to CVD and IRMS, and analyzed the relationships among these errors and suites of diagnostic spectral parameters that are indicative of organic contamination. RESULTS The IM-CRDS technique accurately assessed the δ18 O and δ2 H values of pure waters, but exhibited progressively increasing errors for soil waters, stem waters, and leaf waters. For soils, the errors were attributable to subsampling of isotopically heterogeneous source material, whereas for stems and leaves, they were attributable to spectral interference. Unexpectedly, the magnitude of spectral interference was higher for the solid samples analyzed directly via IM-CRDS than for those originally extracted via CVD and then analyzed by IM-CRDS. CONCLUSIONS There are many types of matrix-bound water samples for which IM-CRDS measurements include significant errors from spectral interference. As a result, spectral analysis and validation should be incorporated into IM-CRDS post-processing procedures. In the future, IM-CRDS performance could be improved through: (i) identification of the compounds that cause spectral interference, and either (ii) modification of the combustion step to completely oxidize these compounds to CO2 , and/or (iii) incorporation of corrections for these compounds into the spectral fitting models used by the CRDS analyzers. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- J E Johnson
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA
- Department of Global Ecology, Carnegie Institution, 260 Panama Street, Stanford, CA, 94305, USA
| | - L Hamann
- School of Natural Resources and the Environment, University of Arizona, Tucson, AZ, 85721, USA
| | - D L Dettman
- Department of Geosciences, University of Arizona, Tucson, AZ, 85721, USA
| | - D Kim-Hak
- Picarro, Inc., 3105 Patrick Henry Drive, Santa Clara, CA, 95054, USA
| | - S W Leavitt
- Laboratory of Tree-Ring Research, University of Arizona, Tucson, AZ, 85721, USA
| | - R K Monson
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA
- Laboratory of Tree-Ring Research, University of Arizona, Tucson, AZ, 85721, USA
| | - S A Papuga
- School of Natural Resources and the Environment, University of Arizona, Tucson, AZ, 85721, USA
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