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Dulinski M, Rozanski K, Pierchala A, Gorczyca Z. Isotope effects accompanying δ 2 H, δ 18 O and δ 17 O analyses of aqueous saline solutions using cavity ring-down laser spectroscopy. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2024; 38:e9680. [PMID: 38212654 DOI: 10.1002/rcm.9680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Revised: 10/22/2023] [Accepted: 11/10/2023] [Indexed: 01/13/2024]
Abstract
RATIONALE The presence of substantial amounts of dissolved salts creates serious difficulties in isotope analyses of water samples using conventional isotope ratio mass spectrometry. Although nowadays laser-based instruments are increasingly used for this purpose, a comprehensive assessment of isotope effects associated with direct analyses of aqueous saline solutions using this technology is lacking. METHODS Here we report the results of laboratory experiments aimed at quantifying isotope effects associated with direct, δ2 H, δ18 O and δ17 O analyses of single-salt solutions and double-salt mixtures prepared with a water of known isotopic composition. Three single-salt solutions (NaCl, CaCl2 and MgSO4 ) and two double-salt mixtures (NaCl + CaCl2 and NaCl + MgSO4 ) were prepared and investigated for a wide range of molalities. The triple-isotope composition of the prepared solutions was analysed with the aid of a Picarro L2140-i Cavity Ring-Down Spectroscopy analyser. RESULTS The NaCl and CaCl2 solutions revealed small negative salt effects, independent of molality and comparable with measurement uncertainty. The MgCl2 solution showed the highest salt effects, reaching saturated solution ca. +2.7‰ (2 H), -3.5‰ (18 O) and -1.7‰ (17 O). Salt effects for the double-salt mixtures generally mirrored the effects observed for the single-salt solutions. The observed salt effects are discussed in the context of processes occurring during the injection of the salt solutions into the vaporizer unit of the CRDS analyser. CONCLUSIONS The presented study has demonstrated feasibility of direct, triple-isotope analyses of aqueous salt solutions using a Picarro L2140-i CRDS analyser for a broad range of salinities up to saturated conditions. Large uncertainties of 17 O-excess determinations for solutions forming hydrated salts preclude the use of this parameter for interpretation purposes.
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Affiliation(s)
- Marek Dulinski
- Faculty of Physics and Applied Computer Science, AGH University of Krakow, Krakow, Poland
| | - Kazimierz Rozanski
- Faculty of Physics and Applied Computer Science, AGH University of Krakow, Krakow, Poland
| | - Anna Pierchala
- Faculty of Physics and Applied Computer Science, AGH University of Krakow, Krakow, Poland
| | - Zbigniew Gorczyca
- Faculty of Physics and Applied Computer Science, AGH University of Krakow, Krakow, Poland
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El-Shenawy MI, Herwartz D, Staubwasser M. A passive method for sampling water in the soil-plant-atmosphere continuum for stable hydrogen and oxygen isotope analyses. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2024; 38:e9646. [PMID: 38124170 DOI: 10.1002/rcm.9646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 09/12/2023] [Accepted: 09/14/2023] [Indexed: 12/23/2023]
Abstract
RATIONALE Hydrogen and oxygen isotopes in water molecules are powerful tools to constrain the dynamics of water cycling within the soil-plant-atmosphere continuum (SPAC). However, the recovery of water from the SPAC requires logistical arrangements and implementation of different time- and cost-consuming techniques in either the field or the laboratory. METHODS We developed a passive method to sample water from the three compartments of the SPAC by using a hygroscopic salt of a high water absorbance capacity (CaCl2 ). This method allows either H2 O(V) -H2 O(L) isotope equilibration in the case of infinite water reservoir (atmospheric water vapor (WV)) or quantitative absorption of water from a finite water reservoir (e.g. soil and plants). The water absorbed by CaCl2 was distilled first and subsequently processed for hydrogen and triple oxygen isotope mass spectrometry analyses. The distillation step can be bypassed when employing isotope analytical techniques that are based on equilibration. RESULTS Our experiments show that anhydrous CaCl2 absorbs WV of 210 ± 6% and 130 ± 6% of its dry weight from an infinite WV reservoir at relative humidity of 60% and 30%, respectively. Chemical and isotope equilibrations between WV and absorbed water were attained within 3 days at room temperature, enabling the back-calculation of the isotope composition of atmospheric WV. Preliminary experiments to extract water from plant and sand (i.e. finite WV reservoir) demonstrate a quasi-complete recovery of water in these matrices without significant isotope fractionation. The reproducibility of our method is better than 1.6‰, 0.32‰, 0.17‰ and 6‰ per meg for δ2 H, δ18 O, δ17 O and 17 O-excess. CONCLUSIONS The CaCl2 -H2 O absorption (passive) method requires very limited logistics in the field facilitating spatial and temporal water vapor/water sampling from atmosphere and soil at low resolution (i.e. average of 3-5 days). Moreover, it allows high sample throughput for the extraction of plant water in the laboratory. The reproducibility of this method is similar to the analytical uncertainty in mass spectrometry analyses.
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Affiliation(s)
- Mohammed I El-Shenawy
- Institute for Geology and Mineralogy, University of Cologne, Cologne, Germany
- Department of Geology, Beni-Suef University, Beni-Suef, Egypt
| | - Daniel Herwartz
- Institute for Geology and Mineralogy, University of Cologne, Cologne, Germany
| | - Michael Staubwasser
- Institute for Geology and Mineralogy, University of Cologne, Cologne, Germany
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Porowski A. AgF desalination procedure for the routine determination of oxygen and hydrogen isotopic composition of saline waters and brines. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2019; 55:41-55. [PMID: 30618268 DOI: 10.1080/10256016.2018.1561449] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 11/29/2018] [Indexed: 06/09/2023]
Abstract
The routine methods for stable oxygen and hydrogen isotope analysis of water involve water-CO2 gas equilibration and water reduction on hot metal (e.g. Zn, Cr, U) and subsequent mass spectrometric analysis of the evolved gases of CO2 and H2 for 18O/16O and 2H/1H ratios, respectively. Precise determination of the isotopic composition of water in brines with application of these standard methods is still problematic and technically often impossible due to detrimental influence of dissolved salts. The new method of brine desalination presented in this study overcomes the problem of the isotope salt effects encountered during the application of the routine techniques for the determination of the isotopic composition of high saline waters. The procedure combines two technical steps: (i) the chemical precipitation of Mg and Ca ions as insoluble non-hydroscopic fluorides, and (ii) the vacuum distillation of water from solution-precipitate mixture. The application of simple vacuum distillation allows full extraction of water and dehydration of remaining salts in a temperature range from 300 to 350 °C without hydrogen and oxygen isotope fractionation. The precision and accuracy of δ18O and δ2H determination of saline waters and brines with prior application of AgF desalination procedure is comparable with that usually obtained for fresh waters.
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Affiliation(s)
- Adam Porowski
- a Polish Academy of Sciences (INGPAN) , Institute of Geological Sciences , Warszawa , Poland
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Oerter EJ, Singleton M, Thaw M, Davisson ML. Water vapor exposure chamber for constant humidity and hydrogen and oxygen stable isotope composition. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2019; 33:89-96. [PMID: 30325553 DOI: 10.1002/rcm.8311] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 10/09/2018] [Accepted: 10/10/2018] [Indexed: 06/08/2023]
Abstract
RATIONALE Water vapor exposure experiments have applications for studying water physisorption and chemisorption hydration and hydroxylation reactions on a wide variety of material surfaces. The stable isotopes of hydrogen and oxygen in the water molecule are useful tracers of water exchange mechanisms and/or rates in such vapor exposure experiments. METHODS We designed and built a humidity chamber system that uses membrane-mediated liquid-vapor exchange of water followed by mixing with dry air to control the relative humidity of air and its δ2 H and δ18 O isotopic composition. We tested the stability and precision of the humidity and its isotopic composition on hourly to 90-day timescales. RESULTS The humidity chamber design reported here is capable of providing relative humidity control to within ±1%, and consistent δ2 H and δ18 O values of the water vapor that are similar to our cavity ringdown spectroscopy (CRDS) measurement precision (δ2 Hvap ± 0.7‰ and δ18 Ovap ± 0.24‰). We quantify the isotopic enrichment effects of Rayleigh distillation in the system and provide information on water reservoir sizes large enough to buffer isotopic enrichment effects to within measurement precision. CONCLUSIONS The humidity chamber design reported here provides a means to create constant δ2 H and δ18 O values over the course of an exposure experiment. The design has applications to a wide range of studies of water sorption on material surfaces from foods and pharmaceuticals to geological materials.
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Affiliation(s)
- Erik J Oerter
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA, 94550, USA
| | - Michael Singleton
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA, 94550, USA
| | - Melissa Thaw
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA, 94550, USA
- University of California, Merced, 5200 Lake Road, Merced, CA, 95340, USA
| | - M Lee Davisson
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA, 94550, USA
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Wassenaar LI, Terzer-Wassmuth S, Douence C, Araguas-Araguas L, Aggarwal PK, Coplen TB. Seeking excellence: An evaluation of 235 international laboratories conducting water isotope analyses by isotope-ratio and laser-absorption spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2018; 32:393-406. [PMID: 29315909 DOI: 10.1002/rcm.8052] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 12/15/2017] [Accepted: 12/18/2017] [Indexed: 06/07/2023]
Abstract
RATIONALE Water stable isotope ratios (δ2 H and δ18 O values) are widely used tracers in environmental studies; hence, accurate and precise assays are required for providing sound scientific information. We tested the analytical performance of 235 international laboratories conducting water isotope analyses using dual-inlet and continuous-flow isotope ratio mass spectrometers and laser spectrometers through a water isotope inter-comparison test. METHODS Eight test water samples were distributed by the IAEA to international stable isotope laboratories. These consisted of a core set of five samples spanning the common δ-range of natural waters, and three optional samples (highly depleted, enriched, and saline). The fifth core sample contained unrevealed trace methanol to assess analyst vigilance to the impact of organic contamination on water isotopic measurements made by all instrument technologies. RESULTS For the core and optional samples ~73 % of laboratories gave acceptable results within 0.2 ‰ and 1.5 ‰ of the reference values for δ18 O and δ2 H, respectively; ~27 % produced unacceptable results. Top performance for δ18 O values was dominated by dual-inlet IRMS laboratories; top performance for δ2 H values was led by laser spectrometer laboratories. Continuous-flow instruments yielded comparatively intermediate results. Trace methanol contamination of water resulted in extreme outlier δ-values for laser instruments, but also affected reactor-based continuous-flow IRMS systems; however, dual-inlet IRMS δ-values were unaffected. CONCLUSIONS Analysis of the laboratory results and their metadata suggested inaccurate or imprecise performance stemmed mainly from skill- and knowledge-based errors including: calculation mistakes, inappropriate or compromised laboratory calibration standards, poorly performing instrumentation, lack of vigilance to contamination, or inattention to unreasonable isotopic outcomes. To counteract common errors, we recommend that laboratories include 1-2 'known' control standards in all autoruns; laser laboratories should screen each autorun for spectral contamination; and all laboratories should evaluate whether derived d-excess values are realistic when both isotope ratios are measured. Combined, these data evaluation strategies should immediately inform the laboratory about fundamental mistakes or compromised samples.
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Affiliation(s)
- L I Wassenaar
- International Atomic Energy Agency, Isotope Hydrology Section, PO Box 100, A-1400, Vienna, Austria
| | - S Terzer-Wassmuth
- International Atomic Energy Agency, Isotope Hydrology Section, PO Box 100, A-1400, Vienna, Austria
| | - C Douence
- International Atomic Energy Agency, Isotope Hydrology Section, PO Box 100, A-1400, Vienna, Austria
| | - L Araguas-Araguas
- International Atomic Energy Agency, Isotope Hydrology Section, PO Box 100, A-1400, Vienna, Austria
| | - P K Aggarwal
- International Atomic Energy Agency, Isotope Hydrology Section, PO Box 100, A-1400, Vienna, Austria
| | - T B Coplen
- US Geological Survey, 431 National Center, 12201Sunrise Valley Drive, Reston, VA, 20192, USA
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Stumpp C, Brüggemann N, Wingate L. Stable Isotope Approaches in Vadose Zone Research. VADOSE ZONE JOURNAL 2018; 17:1-7. [PMID: 0 DOI: 10.2136/vzj2018.05.0096] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Affiliation(s)
- Christine Stumpp
- Institute of Hydraulics and Rural Water Management, Univ. of Natural Resources and Life SciencesViennaAustria
- Institute of Groundwater EcologyHelmholtz Zentrum MünchenMünchenGermany
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Skrzypek G, Ford D. Stable isotope analysis of saline water samples on a cavity ring-down spectroscopy instrument. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:2827-2834. [PMID: 24528490 DOI: 10.1021/es4049412] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The analysis of the stable hydrogen and oxygen isotope composition of water using cavity ring-down spectroscopy (CRDS) instruments utilizing infrared absorption spectroscopy have been comprehensively tested. However, potential limitations of infrared spectroscopy for the analysis of highly saline water have not yet been evaluated. In this study, we assessed uncertainty arising from elevated salt concentrations in water analyzed on a CRDS instrument and the necessity of a correction procedure. We prepared various solutions of mixed salts and separate solutions with individual salts (NaCl, KCl, MgCl2, and CaCl2) using deionized water with a known stable isotope composition. Most of the individual salt and salt mixture solutions (some up to 340 g L(-1)) had δ-values within the range usual for CRDS analytical uncertainty (0.1‰ for δ (18)O and 1.0‰ for δ (2)H). Results were not compromised even when the total load of salt in the vaporizer reached ∼38.5 mg (equivalent to build up after running ∼100 ocean water samples). Therefore, highly saline mixtures can be successfully analyzed using CRDS, except highly concentrated MgCl2 solutions, without the need for an additional correction if the vaporizer is frequently cleaned and MgCl2 concentration in water is relatively low.
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Affiliation(s)
- Grzegorz Skrzypek
- West Australian Biogeochemistry Centre, School of Plant Biology, The University of Western Australia , MO90, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
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Wassenaar LI, Coplen TB, Aggarwal PK. Approaches for achieving long-term accuracy and precision of δ18O and δ2H for waters analyzed using laser absorption spectrometers. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:1123-1131. [PMID: 24328223 DOI: 10.1021/es403354n] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The measurement of δ(2)H and δ(18)O in water samples by laser absorption spectroscopy (LAS) are adopted increasingly in hydrologic and environmental studies. Although LAS instrumentation is easy to use, its incorporation into laboratory operations is not as easy, owing to extensive offline data manipulation required for outlier detection, derivation and application of algorithms to correct for between-sample memory, correcting for linear and nonlinear instrumental drift, VSMOW-SLAP scale normalization, and in maintaining long-term QA/QC audits. Here we propose a series of standardized water-isotope LAS performance tests and routine sample analysis templates, recommended procedural guidelines, and new data processing software (LIMS for Lasers) that altogether enables new and current LAS users to achieve and sustain long-term δ(2)H and δ(18)O accuracy and precision for these important isotopic assays.
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Affiliation(s)
- Leonard I Wassenaar
- Isotope Hydrology Section, International Atomic Energy Agency , Vienna International Center, Vienna, Austria , A-1400
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