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Haberstroh S, Kübert A, Werner C. Two common pitfalls in the analysis of water-stable isotopologues with cryogenic vacuum extraction and cavity ring-down spectroscopy. ANALYTICAL SCIENCE ADVANCES 2024; 5:2300053. [PMID: 38827022 PMCID: PMC11142394 DOI: 10.1002/ansa.202300053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2023] [Revised: 01/08/2024] [Accepted: 01/11/2024] [Indexed: 06/04/2024]
Abstract
Water stable isotopologue analysis is widely used to disentangle ecohydrological processes. Yet, there are increasing reports of measurement uncertainties for established and emerging methods, such as cryogenic vacuum extraction (CVE) or cavity ring-down spectroscopy (CRDS). With this study, we investigate two pitfalls, that potentially contribute to uncertainties in water-stable isotopologue research. To investigate fractionation sources in CVE, we extracted pure water of known isotopic composition with cotton, glass wool or without cover and compared the isotopologue results with non-extracted reference samples. To characterise the dependency of δ2H and δ18O on the water mixing ratio in CRDS, which is of high importance for in-situ applications with large natural variations in mixing ratios, we chose samples with a large range of isotopic compositions and determined δ2H and δ18O for different water mixing ratios with two CRDS analysers (Picarro, Inc.). Cotton wool had a strong fractionation effect on δ2H values, which increased with more 2H-enriched samples. δ2H and δ18O values showed a strong dependency on the water mixing ratio analysed with CRDS with differences of up to 34.5‰ (δ2H) and 3.9‰ (δ18O) for the same sample at different mixing ratios. CVE and CRDS, now routinely applied in water stable isotopologue research, come with pitfalls, namely fractionation effects of cover materials and water mixing ratio dependencies of δ2H and δ18O, which can lead to erroneous isotopologue results and thus, invalid conclusions about (ecohydrological) processes. These practical issues identified here should be reported and addressed adequately in water-stable isotopologue research.
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Affiliation(s)
- Simon Haberstroh
- Ecosystem PhysiologyFaculty of Environment and Natural ResourcesInstitute of Earth and Environmental SciencesUniversity FreiburgFreiburgGermany
| | - Angelika Kübert
- Ecosystem PhysiologyFaculty of Environment and Natural ResourcesInstitute of Earth and Environmental SciencesUniversity FreiburgFreiburgGermany
- Institute for Atmospheric and Earth System Research (INAR)University of HelsinkiHelsinkiFinland
| | - Christiane Werner
- Ecosystem PhysiologyFaculty of Environment and Natural ResourcesInstitute of Earth and Environmental SciencesUniversity FreiburgFreiburgGermany
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2
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Kühnhammer K, van Haren J, Kübert A, Bailey K, Dubbert M, Hu J, Ladd SN, Meredith LK, Werner C, Beyer M. Deep roots mitigate drought impacts on tropical trees despite limited quantitative contribution to transpiration. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 893:164763. [PMID: 37308023 PMCID: PMC10331952 DOI: 10.1016/j.scitotenv.2023.164763] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 06/05/2023] [Accepted: 06/07/2023] [Indexed: 06/14/2023]
Abstract
Deep rooting is considered a central drought-mitigation trait with vast impact on ecosystem water cycling. Despite its importance, little is known about the overall quantitative water use via deep roots and dynamic shifts of water uptake depths with changing ambient conditions. Knowledge is especially sparse for tropical trees. Therefore, we conducted a drought, deep soil water labeling and re-wetting experiment at Biosphere 2 Tropical Rainforest. We used in situ methods to determine water stable isotope values in soil and tree water in high temporal resolution. Complemented by soil and stem water content and sap flow measurements we determined percentages and quantities of deep-water in total root water uptake dynamics of different tree species. All canopy trees had access to deep-water (max. uptake depth 3.3 m), with contributions to transpiration ranging between 21 % and 90 % during drought, when surface soil water availability was limited. Our results suggest that deep soil is an essential water source for tropical trees that delays potentially detrimental drops in plant water potentials and stem water content when surface soil water is limited and could hence mitigate the impacts of increasing drought occurrence and intensity as a consequence of climate change. Quantitatively, however, the amount of deep-water uptake was low due to the trees' reduction of sap flow during drought. Total water uptake largely followed surface soil water availability and trees switched back their uptake depth dynamically, from deep to shallow soils, following rainfall. Total transpiration fluxes were hence largely driven by precipitation input.
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Affiliation(s)
- Kathrin Kühnhammer
- IGOE, Environmental Geochemistry, TU Braunschweig, Langer Kamp 19c, 38106 Braunschweig, Germany; Ecosystem Physiology, University of Freiburg, Georges-Köhler-Allee 53/54, 79110 Freiburg, Germany.
| | - Joost van Haren
- Biosphere 2, University of Arizona, 32540 S Biosphere Road, Oracle, AZ 85623, USA; Honors College, University of Arizona, 1101 E. Mabel St., Tucson, AZ 85719, USA
| | - Angelika Kübert
- Ecosystem Physiology, University of Freiburg, Georges-Köhler-Allee 53/54, 79110 Freiburg, Germany; Institute for Atmospheric and Earth System Research, University of Helsinki, P.O. Box 68, Pietari Kalmin katu 5, 00014 Helsinki, Finland
| | - Kinzie Bailey
- School of Natural Resources and the Environment, University of Arizona, 1064 E Lowell St, Tucson, AZ 85721, USA
| | - Maren Dubbert
- Ecosystem Physiology, University of Freiburg, Georges-Köhler-Allee 53/54, 79110 Freiburg, Germany; Isotope Biogeochemistry and Gasfluxes, ZALF, Eberswalder Straße 84, 15374 Müncheberg, Germany
| | - Jia Hu
- School of Natural Resources and the Environment, University of Arizona, 1064 E Lowell St, Tucson, AZ 85721, USA
| | - S Nemiah Ladd
- Ecosystem Physiology, University of Freiburg, Georges-Köhler-Allee 53/54, 79110 Freiburg, Germany; Department of Environmental Sciences, University of Basel, Bernoullistrasse 32, 4056 Basel, Switzerland
| | - Laura K Meredith
- Biosphere 2, University of Arizona, 32540 S Biosphere Road, Oracle, AZ 85623, USA; School of Natural Resources and the Environment, University of Arizona, 1064 E Lowell St, Tucson, AZ 85721, USA
| | - Christiane Werner
- Ecosystem Physiology, University of Freiburg, Georges-Köhler-Allee 53/54, 79110 Freiburg, Germany
| | - Matthias Beyer
- IGOE, Environmental Geochemistry, TU Braunschweig, Langer Kamp 19c, 38106 Braunschweig, Germany
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Kübert A, Dubbert M, Bamberger I, Kühnhammer K, Beyer M, van Haren J, Bailey K, Hu J, Meredith LK, Nemiah Ladd S, Werner C. Tracing plant source water dynamics during drought by continuous transpiration measurements: An in-situ stable isotope approach. PLANT, CELL & ENVIRONMENT 2023; 46:133-149. [PMID: 36305510 DOI: 10.1111/pce.14475] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 10/21/2022] [Accepted: 10/23/2022] [Indexed: 06/16/2023]
Abstract
The isotopic composition of xylem water (δX ) is of considerable interest for plant source water studies. In-situ monitored isotopic composition of transpired water (δT ) could provide a nondestructive proxy for δX -values. Using flow-through leaf chambers, we monitored 2-hourly δT -dynamics in two tropical plant species, one canopy-forming tree and one understory herbaceous species. In an enclosed rainforest (Biosphere 2), we observed δT -dynamics in response to an experimental severe drought, followed by a 2 H deep-water pulse applied belowground before starting regular rain. We also sampled branches to obtain δX -values from cryogenic vacuum extraction (CVE). Daily flux-weighted δ18 OT -values were a good proxy for δ18 OX -values under well-watered and drought conditions that matched the rainforest's water source. Transpiration-derived δ18 OX -values were mostly lower than CVE-derived values. Transpiration-derived δ2 HX -values were relatively high compared to source water and consistently higher than CVE-derived values during drought. Tracing the 2 H deep-water pulse in real-time showed distinct water uptake and transport responses: a fast and strong contribution of deep water to canopy tree transpiration contrasting with a slow and limited contribution to understory species transpiration. Thus, the in-situ transpiration method is a promising tool to capture rapid dynamics in plant water uptake and use by both woody and nonwoody species.
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Affiliation(s)
- Angelika Kübert
- Ecosystem Physiology, University of Freiburg, Freiburg, Germany
- Institute for Atmospheric and Earth System Research, University of Helsinki, Helsinki, Finland
| | - Maren Dubbert
- Isotope Biogeochemistry and Gas Fluxes, Landscape Functioning, ZALF, Müncheberg, Germany
| | - Ines Bamberger
- Atmospheric Chemistry Group, University of Bayreuth, Bayreuth, Germany
| | - Kathrin Kühnhammer
- Ecosystem Physiology, University of Freiburg, Freiburg, Germany
- Institute for Geoecology, Technical University of Braunschweig, Braunschweig, Germany
| | - Matthias Beyer
- Institute for Geoecology, Technical University of Braunschweig, Braunschweig, Germany
| | - Joost van Haren
- Biosphere 2, University of Arizona, Tucson, Arizona, USA
- Honors College, University of Arizona, Tucson, Arizona, USA
| | - Kinzie Bailey
- School of Natural Resources and the Environment, University of Arizona, Tucson, Arizona, USA
| | - Jia Hu
- School of Natural Resources and the Environment, University of Arizona, Tucson, Arizona, USA
| | - Laura K Meredith
- Biosphere 2, University of Arizona, Tucson, Arizona, USA
- School of Natural Resources and the Environment, University of Arizona, Tucson, Arizona, USA
| | - S Nemiah Ladd
- Ecosystem Physiology, University of Freiburg, Freiburg, Germany
- Biogeochemistry Group, Department of Environmental Sciences, University of Basel, Basel, Switzerland
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Voigt C, Vallet-Coulomb C, Piel C, Alexandre A. 17 O-excess and d-excess of atmospheric water vapor measured by cavity ring-down spectrometry: Evidence of a matrix effect and implication for the calibration procedure. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2022; 36:e9227. [PMID: 34845759 DOI: 10.1002/rcm.9227] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 11/22/2021] [Accepted: 11/22/2021] [Indexed: 06/13/2023]
Abstract
RATIONALE Producing robust high-frequency time series of raw atmospheric water vapor isotope data using laser spectrometry requires accurate calibration. In particular, the chemical composition of the analyzed sample gas can cause isotope bias. This study assesses the matrix effect on calibrated δ17 O, δ18 O, δ2 H, 17 O-excess, and d-excess values of atmospheric water vapor. METHODS A Picarro L2140-i cavity ring-down spectrometer with an autosampler and a vaporizer is used to analyze δ17 O, δ18 O, δ2 H, 17 O-excess, and d-excess of two water standards. Isotope data obtained using synthetic air and dry ambient air as carrier gas at water mixing ratios ranging from 2000 to 30 000 ppmv are compared. Based on the results, atmospheric water vapor measurements are calibrated. The expected precision is estimated by Monte Carlo simulation. RESULTS The dry air source strongly impacts raw isotope values of the two water standards but has no effect on the mixing ratio dependency functions. When synthetic air is used, δ17 O, δ18 O, and 17 O-excess of calibrated atmospheric water vapor are overestimated by 0.6‰, 0.7‰, and 217 per meg, respectively, whereas δ2 H and d-excess are underestimated by 1.5‰ and 7.3‰. Optimum precisions for the calibrated δ17 O, δ18 O, δ2 H, 17 O-excess, and d-excess values and 12 min integration time are 0.02‰, 0.03‰, 0.4‰, 14 per meg, and 0.4‰, respectively. CONCLUSIONS Regarding the obtained results, recommendations for the calibration of atmospheric water vapor isotope measurements are presented. The necessity to use dry ambient air as dry air source when running the standards for calibration is pointed out as a prerequisite for accurate atmospheric water vapor 17 O-excess and d-excess measurements.
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Affiliation(s)
- Claudia Voigt
- Aix Marseille Univ, CNRS, IRD, INRAE, CEREGE, Aix-en-Provence, France
| | | | - Clément Piel
- ECOTRON Européen de Montpellier, UAR 3248, Centre National de la Recherche Scientifique (CNRS), Campus de Baillarguet, Montferrier-sur-Lez, France
| | - Anne Alexandre
- Aix Marseille Univ, CNRS, IRD, INRAE, CEREGE, Aix-en-Provence, France
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Kühnhammer K, Dahlmann A, Iraheta A, Gerchow M, Birkel C, Marshall JD, Beyer M. Continuous in situ measurements of water stable isotopes in soils, tree trunk and root xylem: Field approval. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2022; 36:e9232. [PMID: 34862674 DOI: 10.1002/rcm.9232] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 11/26/2021] [Accepted: 11/27/2021] [Indexed: 06/13/2023]
Abstract
RATIONALE New methods to measure stable isotopes of soil and tree water directly in the field enable us to increase the temporal resolution of obtained data and advance our knowledge on the dynamics of soil and plant water fluxes. Only few field applications exist. However, these are needed to further improve novel methods and hence exploit their full potential. METHODS We tested the borehole equilibration method in the field and collected in situ and destructive samples of stable isotopes of soil, trunk and root xylem water over a 2.5-month experiment in a tropical dry forest under natural abundance conditions and following labelled irrigation. Water from destructive samples was extracted using cryogenic vacuum extraction. Isotope ratios were determined with IRIS instruments using cavity ring-down spectroscopy both in the field and in the laboratory. RESULTS In general, timelines of both methods agreed well for both soil and xylem samples. Irrigation labelled with heavy hydrogen isotopes clearly impacted the isotope composition of soil water and one of the two studied tree species. Inter-method deviations increased in consequence of labelling, which revealed their different capabilities to cover spatial and temporal heterogeneities. CONCLUSIONS We applied the novel borehole equilibration method in a remote field location. Our experiment reinforced the potential of this in situ method for measuring xylem water isotopes in both tree trunks and roots and confirmed the reliability of gas permeable soil probes. However, in situ xylem measurements should be further developed to reduce the uncertainty within the range of natural abundance and hence enable their full potential.
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Affiliation(s)
- Kathrin Kühnhammer
- IGOE, Environmental Geochemistry, Braunschweig, Germany
- Ecosystem Physiology, University of Freiburg, Freiburg, Germany
| | - Adrian Dahlmann
- IGOE, Environmental Geochemistry, Braunschweig, Germany
- Ecosystem Physiology, University of Freiburg, Freiburg, Germany
| | | | | | - Christian Birkel
- Department of Geography and Water and Global Change Observatory, Universidad de Costa Rica (UCR), San José, Costa Rica
| | - John D Marshall
- Department of Forest Ecology and Management, Faculty of Forest Sciences, Swedish University of Agricultural Sciences, Umeå, Sweden
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Kühnhammer K, Kübert A, Brüggemann N, Deseano Diaz P, van Dusschoten D, Javaux M, Merz S, Vereecken H, Dubbert M, Rothfuss Y. Investigating the root plasticity response of Centaurea jacea to soil water availability changes from isotopic analysis. THE NEW PHYTOLOGIST 2020; 226:98-110. [PMID: 31792975 DOI: 10.1111/nph.16352] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 11/21/2019] [Indexed: 06/10/2023]
Abstract
Root water uptake is a key ecohydrological process for which a physically based understanding has been developed in the past decades. However, due to methodological constraints, knowledge gaps remain about the plastic response of whole plant root systems to a rapidly changing environment. We designed a laboratory system for nondestructive monitoring of stable isotopic composition in plant transpiration of a herbaceous species (Centaurea jacea) and of soil water across depths, taking advantage of newly developed in situ methods. Daily root water uptake profiles were obtained using a statistical Bayesian multisource mixing model. Fast shifts in the isotopic composition of both soil and transpiration water could be observed with the setup and translated into dynamic and pronounced shifts of the root water uptake profile, even in well watered conditions. The incorporation of plant physiological and soil physical information into statistical modelling improved the model output. A simple exercise of water balance closure underlined the nonunique relationship between root water uptake profile on the one hand, and water content and root distribution profiles on the other, illustrating the continuous adaption of the plant water uptake as a function of its root hydraulic architecture and soil water availability during the experiment.
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Affiliation(s)
- Kathrin Kühnhammer
- Institute of Bio- and Geosciences, Agrosphere Institute (IBG-3), Forschungszentrum Jülich GmbH, Leo-Brandt-Straße, D-52425, Jülich, Germany
| | - Angelika Kübert
- Ecosystem Physiology, University Freiburg, D-79104, Freiburg, Germany
| | - Nicolas Brüggemann
- Institute of Bio- and Geosciences, Agrosphere Institute (IBG-3), Forschungszentrum Jülich GmbH, Leo-Brandt-Straße, D-52425, Jülich, Germany
| | - Paulina Deseano Diaz
- Institute of Bio- and Geosciences, Agrosphere Institute (IBG-3), Forschungszentrum Jülich GmbH, Leo-Brandt-Straße, D-52425, Jülich, Germany
| | - Dagmar van Dusschoten
- Institute of Bio- and Geosciences, Plant Sciences (IBG-2), Forschungszentrum Jülich GmbH, Leo-Brandt-Straße, D-52425, Jülich, Germany
| | - Mathieu Javaux
- Institute of Bio- and Geosciences, Agrosphere Institute (IBG-3), Forschungszentrum Jülich GmbH, Leo-Brandt-Straße, D-52425, Jülich, Germany
- Earth and Life Institute, Environmental Sciences (ELIE), Université catholique de Louvain (UCL), B-1348, Louvain-la-Neuve, Belgium
| | - Steffen Merz
- Institute of Energy and Climate Research, Fundamental Electrochemistry (IEK-9), Forschungszentrum Jülich GmbH, Leo-Brandt-Straße, D-52425, Jülich, Germany
| | - Harry Vereecken
- Institute of Bio- and Geosciences, Agrosphere Institute (IBG-3), Forschungszentrum Jülich GmbH, Leo-Brandt-Straße, D-52425, Jülich, Germany
| | - Maren Dubbert
- Ecosystem Physiology, University Freiburg, D-79104, Freiburg, Germany
| | - Youri Rothfuss
- Institute of Bio- and Geosciences, Agrosphere Institute (IBG-3), Forschungszentrum Jülich GmbH, Leo-Brandt-Straße, D-52425, Jülich, Germany
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Kübert A, Paulus S, Dahlmann A, Werner C, Rothfuss Y, Orlowski N, Dubbert M. Water Stable Isotopes in Ecohydrological Field Research: Comparison Between In Situ and Destructive Monitoring Methods to Determine Soil Water Isotopic Signatures. FRONTIERS IN PLANT SCIENCE 2020; 11:387. [PMID: 32346381 PMCID: PMC7171290 DOI: 10.3389/fpls.2020.00387] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 03/18/2020] [Indexed: 05/15/2023]
Abstract
Ecohydrological isotope based field research is often constrained by a lack of temporally explicit soil water data, usually related to the choice of destructive sampling in the field and subsequent analysis in the laboratory. New techniques based on gas permeable membranes allow to sample soil water vapor in situ and infer soil liquid water isotopic signatures. Here, a membrane-based in situ soil water vapor sampling method was tested at a grassland site in Freiburg, Germany. It was further compared with two commonly used destructive sampling approaches for determination of soil liquid water isotopic signatures: cryogenic vacuum extraction and centrifugation. All methods were tested under semi-controlled field conditions, conducting an experiment with dry-wet cycling and two isotopically different labeling irrigation waters. We found mean absolute differences between cryogenic vacuum extraction and in situ vapor measurements of 0.3-14.2‰ (δ18O) and 0.4-152.2‰ (δ2H) for soil liquid water. The smallest differences were found under natural abundance conditions of 2H and 18O, the strongest differences were observed after irrigation with labeled waters. Labeling strongly increased the isotopic variation in soil water: Mean soil water isotopic signatures derived by cryogenic vacuum extraction were -11.6 ± 10.9‰ (δ18O) and +61.9 ± 266.3‰ (δ2H). The in situ soil water vapor method showed isotopic signatures of -12.5 ± 9.4‰ (δ18O) and +169.3 ± 261.5‰ (δ2H). Centrifugation was unsuccessful for soil samples due to low water recovery rates. It is therefore not recommended. Our study highlights that the in situ soil water vapor method captures the temporal dynamics in the isotopic signature of soil water well while the destructive approach also includes the natural lateral isotopic heterogeneity. The different advantages and limitations of the three methods regarding setup, handling and costs are discussed. The choice of method should not only consider prevailing environmental conditions but the experimental design and goal. We see a very promising tool in the in situ soil water vapor method, capturing both temporal developments and spatial variability of soil water processes.
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Affiliation(s)
- Angelika Kübert
- Ecosystem Physiology, University of Freiburg, Freiburg, Germany
- *Correspondence: Angelika Kübert,
| | - Sinikka Paulus
- Ecosystem Physiology, University of Freiburg, Freiburg, Germany
- Department of Biogeochemical Integration, Max Planck Institute for Biogeochemistry, Jena, Germany
| | - Adrian Dahlmann
- Ecosystem Physiology, University of Freiburg, Freiburg, Germany
| | | | - Youri Rothfuss
- Institute of Bio- and Geosciences, Agrosphere Institute (IBG-3), Jülich, Germany
| | | | - Maren Dubbert
- Ecosystem Physiology, University of Freiburg, Freiburg, Germany
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Mattei A, Barbecot F, Guillon S, Goblet P, Hélie JF, Meyzonnat G. Improved accuracy and precision of water stable isotope measurements using the direct vapour equilibration method. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2019; 33:1613-1622. [PMID: 31141839 DOI: 10.1002/rcm.8494] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 05/20/2019] [Accepted: 05/22/2019] [Indexed: 06/09/2023]
Abstract
RATIONALE A method to measure the δ2 H and δ18 O composition of pore water in soil samples using direct vapour equilibration and laser spectrometry was first described in 2008, and was rapidly adopted. Here, we describe an improved setup to measure pore water δ2 H and δ18 O values through direct vapour equilibration with a laser spectrometer, combining a liquid and a vapour mode for water isotope analyses, and resulting in improved accuracy. METHODS We first tested new gas sampling bags as part of the equilibration protocol. Then, to assess measurement accuracy, vapour samples from equilibrated liquid waters of known isotope composition were measured in the liquid mode of the analyser using the new setup as well as the manufacturer's vapour mode. Various modes of preparing liquid water standards, namely equilibration, nebulisation, and vapourisation, were tested to determine the best calibration in terms of accuracy. Finally, the proposed modified liquid setup was validated by analysing water vapour equilibrated from soil pore water of a known composition. RESULTS The δ2 H and δ18 O measurements were found to be more accurate by the modified liquid mode than by the factory-setup vapour mode. The strong and non-linear dependence of measured δ2 H and δ18 O values on H2 O concentration in vapour mode, especially at concentrations equal to the vapour pressure saturation typically found in laboratories, is problematic for corrections. Regarding calibration and standards, the use of two equilibrated liquid water standards was found to best calibrate measurements in the modified liquid setup. Finally, the modified liquid mode setup and its calibration, as described here, were shown to be appropriate for soil pore water analysis. CONCLUSIONS The proposed modified setup results in more precise δ2 H and δ18 O soil pore water values than the usual protocols. An average standard deviation of 0.04‰ for δ18 O values and 0.3‰ for δ2 H values, based on 228 soil sample analyses, was obtained.
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Affiliation(s)
- Alexandra Mattei
- GEOTOP, Département des sciences de la Terre et de l'atmosphère, Université du Québec à Montréal, CP8888 succ. Centre-Ville, Montréal, QC, H3C 3P8, Canada
- MINES ParisTech, PSL Research University, Centre for Geosciences and Geoengineering, 35 rue Saint-Honoré, 77300, Fontainebleau, France
| | - Florent Barbecot
- GEOTOP, Département des sciences de la Terre et de l'atmosphère, Université du Québec à Montréal, CP8888 succ. Centre-Ville, Montréal, QC, H3C 3P8, Canada
| | - Sophie Guillon
- MINES ParisTech, PSL Research University, Centre for Geosciences and Geoengineering, 35 rue Saint-Honoré, 77300, Fontainebleau, France
| | - Patrick Goblet
- MINES ParisTech, PSL Research University, Centre for Geosciences and Geoengineering, 35 rue Saint-Honoré, 77300, Fontainebleau, France
| | - Jean-François Hélie
- GEOTOP, Département des sciences de la Terre et de l'atmosphère, Université du Québec à Montréal, CP8888 succ. Centre-Ville, Montréal, QC, H3C 3P8, Canada
| | - Guillaume Meyzonnat
- GEOTOP, Département des sciences de la Terre et de l'atmosphère, Université du Québec à Montréal, CP8888 succ. Centre-Ville, Montréal, QC, H3C 3P8, Canada
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A Review on the Methods for Observing the Substance and Energy Exchange between Atmosphere Boundary Layer and Free Troposphere. ATMOSPHERE 2018. [DOI: 10.3390/atmos9120460] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Atmosphere boundary layer (ABL or BL) acts as a pivotal part in the climate by regulating the vertical exchange of moisture, aerosol, trace gases and energy between the earth surface and free troposphere (FT). However, compared with research on the exchange between earth surface and ABL, there are fewer researches on the exchange between ABL and FT, especially when it comes to the quantitative measurement of vertical exchange flux between them. In this paper, a number of various methodologies for investigating the exchange of the substance and energy between ABL and FT are reviewed as follows: (1) methods to obtain entrainment rate, which include method by investigating the height of inversion layer, method of flux-jump, estimating with dataset from the ASTEX Lagrangian Experiments and method of using satellite observations and Microwave Imager; (2) mass budget method, which can yield quantitative measurements of exchange flux between ABL and FT; (3) qualitative measurements: method based on Rayleigh distillation and mixing processes, methods of ground-based remote sensing and airborne tracer-tracer relationship/ratio method.
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10
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Millar C, Pratt D, Schneider DJ, McDonnell JJ. A comparison of extraction systems for plant water stable isotope analysis. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2018; 32:1031-1044. [PMID: 29645300 DOI: 10.1002/rcm.8136] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 03/26/2018] [Accepted: 03/27/2018] [Indexed: 05/27/2023]
Abstract
RATIONALE The stable isotope ratios of water (δ2 H and δ18 O values) have been widely used to trace water in plants in a variety of physiological, ecohydrological, biogeochemical and hydrological studies. In such work, the analyte must first be extracted from samples, prior to isotopic analysis. While cryogenic vacuum distillation is currently the most widely used method reported in the literature, a variety of extraction-collection-analysis methods exist. A formal inter-method comparison on plant tissues has yet to be carried out. METHODS We performed an inter-method comparison of six plant water extraction techniques: direct vapour equilibration, microwave extraction, two unique versions of cryogenic vacuum distillation, centrifugation, and high-pressure mechanical squeezing. These methods were applied to four isotopically unique plant portions (head, stem, leaf, and root crown) of spring wheat (Triticum aestivum L.). Extracted plant water was analyzed via spectrometric (OA-ICOS) and mass-based (IRMS) analysis systems when possible. Spring wheat was grown under controlled conditions with irrigation inputs of a known isotopic composition. RESULTS The tested methods of extraction yielded markedly different isotopic signatures. Centrifugation, microwave extraction, direct vapour equilibration, and high-pressure mechanical squeezing produced water more enriched in 2 H and 18 O content. Both cryogenic vacuum distillation systems and the high-pressure mechanical squeezing method produced water more depleted in 2 H and 18 O content, depending upon the plant portion extracted. The various methods also produced differing concentrations of co-extracted organic compounds, depending on the mode of extraction. Overall, the direct vapor equilibration method outperformed all other methods. CONCLUSIONS Despite its popularity, cryogenic vacuum distillation was outperformed by the direct vapor equilibration method in terms of limited co-extraction of volatile organic compounds, rapid sample throughput, and near instantaneous returned stable isotope results. More research is now needed with other plant species, especially woody plants, to see how far the findings from this study could be extended.
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Affiliation(s)
- Cody Millar
- Global Institute for Water Security, School of Environment and Sustainability, University of Saskatchewan, 11 Innovation Boulevard, Saskatoon, SK, S7N 3H5, Canada
| | - Dyan Pratt
- Global Institute for Water Security, School of Environment and Sustainability, University of Saskatchewan, 11 Innovation Boulevard, Saskatoon, SK, S7N 3H5, Canada
| | - David J Schneider
- Global Institute for Food Security, University of Saskatchewan, 110 Gymnasium Place, Saskatoon, SK, S7N 4J8, Canada
| | - Jeffrey J McDonnell
- Global Institute for Water Security, School of Environment and Sustainability, University of Saskatchewan, 11 Innovation Boulevard, Saskatoon, SK, S7N 3H5, Canada
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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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Galewsky J, Steen-Larsen HC, Field RD, Worden J, Risi C, Schneider M. Stable isotopes in atmospheric water vapor and applications to the hydrologic cycle. REVIEWS OF GEOPHYSICS (WASHINGTON, D.C. : 1985) 2016; 54:809-865. [PMID: 32661517 PMCID: PMC7357203 DOI: 10.1002/2015rg000512] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The measurement and simulation of water vapor isotopic composition has matured rapidly over the last decade, with long-term datasets and comprehensive modeling capabilities now available. Theories for water vapor isotopic composition have been developed by extending the theories that have been used for the isotopic composition of precipitation to include a more nuanced understanding of evaporation, large-scale mixing, deep convection, and kinetic fractionation. The technologies for in-situ and remote sensing measurements of water vapor isotopic composition have developed especially rapidly over the last decade, with discrete water vapor sampling methods, based on mass spectroscopy, giving way to laser spectroscopic methods and satellite- and ground-based infrared absorption techniques. The simulation of water vapor isotopic composition has evolved from General Circulation Model (GCM) methods for simulating precipitation isotopic composition to sophisticated isotope-enabled microphysics schemes using higher-order moments for water- and ice-size distributions. The incorporation of isotopes into GCMs has enabled more detailed diagnostics of the water cycle and has led to improvements in its simulation. The combination of improved measurement and modeling of water vapor isotopic composition opens the door to new advances in our understanding of the atmospheric water cycle, in processes ranging from the marine boundary layer, through deep convection and tropospheric mixing, and into the water cycle of the stratosphere. Finally, studies of the processes governing modern water vapor isotopic composition provide an improved framework for the interpretation of paleoclimate proxy records of the hydrological cycle.
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Affiliation(s)
- Joseph Galewsky
- Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico, USA
| | | | - Robert D Field
- NASA Goddard Institute for Space Studies, New York, New York, USA
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York, USA
| | - John Worden
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Camille Risi
- Laboratoire de Meteorologie Dynamique, Institut Pierre Simon Laplace, Centre National de la Recherche Scientifique, Paris, France
| | - Matthias Schneider
- Institute for Meteorology and Climate Research (IMK-ASF), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
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Volkmann THM, Kühnhammer K, Herbstritt B, Gessler A, Weiler M. A method for in situ monitoring of the isotope composition of tree xylem water using laser spectroscopy. PLANT, CELL & ENVIRONMENT 2016; 39:2055-63. [PMID: 27260852 DOI: 10.1111/pce.12725] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 01/26/2016] [Accepted: 01/27/2016] [Indexed: 05/27/2023]
Abstract
Field studies analyzing the stable isotope composition of xylem water are providing important information on ecosystem water relations. However, the capacity of stable isotopes to characterize the functioning of plants in their environment has not been fully explored because of methodological constraints on the extent and resolution at which samples could be collected and analysed. Here, we introduce an in situ method offering the potential to continuously monitor the stable isotope composition of tree xylem water via its vapour phase using a commercial laser-based isotope analyser and compact microporous probes installed into the xylem. Our technique enables efficient high-frequency measurement with intervals of only a few minutes per sample while eliminating the need for costly and cumbersome destructive collection of plant material and laboratory-based processing. We present field observations of xylem water hydrogen and oxygen isotope compositions obtained over several days including a labelled irrigation event and compare them against results from concurrent destructive sampling with cryogenic distillation and mass spectrometric analysis. The data demonstrate that temporal changes as well as spatial patterns of integration in xylem water isotope composition can be resolved through direct measurement. The new technique can therefore present a valuable tool to study the hydraulic architecture and water utilization of trees.
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Affiliation(s)
- Till H M Volkmann
- Chair of Hydrology, Faculty of Environment and Natural Resources, University of Freiburg, Fahnenbergplatz, 79098, Freiburg, Germany
- Biosphere 2 Earth Science, University of Arizona, 845 N. Park Avenue, Tucson, AZ, 85721, USA
| | - Kathrin Kühnhammer
- Chair of Hydrology, Faculty of Environment and Natural Resources, University of Freiburg, Fahnenbergplatz, 79098, Freiburg, Germany
| | - Barbara Herbstritt
- Chair of Hydrology, Faculty of Environment and Natural Resources, University of Freiburg, Fahnenbergplatz, 79098, Freiburg, Germany
| | - Arthur Gessler
- Institute for Landscape Biogeochemistry, Leibniz Centre for Agricultural Landscape Research (ZALF), Eberswalder Straße 84, 15374, Müncheberg, Germany
- Research Unit Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Zürcherstrasse 111, 8903, Birmensdorf, Switzerland
- Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Altensteinstrasse 6, 14195, Berlin, Germany
| | - Markus Weiler
- Chair of Hydrology, Faculty of Environment and Natural Resources, University of Freiburg, Fahnenbergplatz, 79098, Freiburg, Germany
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Pratt DL, Lu M, Lee Barbour S, Jim Hendry M. An evaluation of materials and methods for vapour measurement of the isotopic composition of pore water in deep, unsaturated zones. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2016; 52:529-543. [PMID: 27002493 DOI: 10.1080/10256016.2016.1151423] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 01/08/2016] [Indexed: 06/05/2023]
Abstract
The development of in situ vapour sampling methods to measure δ(2)H and δ(18)O in pore water of deep, unsaturated soil profiles, including mine tailings and waste rock, is required to improve our ability to track water migration through these deposits. To develop appropriate field sampling methods, a laboratory study was first undertaken to evaluate potential materials and sampling methods to collect and analyse vapour samples from unsaturated mine waste. Field methods were developed based on these findings and tested at two mine sites using either on-site analyses with a portable isotope laser spectrometer or sample collection and storage prior to laboratory analyses. The field sites included a series of deep (>50 m) multiport profiles within a coal waste rock dump and open wells installed in a sand tailings dyke at an oil sands mine. Laboratory results show that memory effects in sample bags and tubing require 3-5 pore volumes of vapour flushing prior to sample collection and sample storage times are limited to 24 h. Field sampling highlighted a number of challenges including the need to correct for sample humidity and in situ temperature. Best results were obtained when a portable laser spectrometer was used to measure vapour samples in situ.
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Affiliation(s)
- Dyan L Pratt
- a Civil & Geological Engineering , University of Saskatchewan , Saskatoon , SK , Canada
| | - Mengna Lu
- a Civil & Geological Engineering , University of Saskatchewan , Saskatoon , SK , Canada
| | - S Lee Barbour
- a Civil & Geological Engineering , University of Saskatchewan , Saskatoon , SK , Canada
| | - M Jim Hendry
- b Geological Sciences , University of Saskatchewan , Saskatoon , SK , Canada
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Liu J, Xiao C, Ding M, Ren J. Variations in stable hydrogen and oxygen isotopes in atmospheric water vapor in the marine boundary layer across a wide latitude range. J Environ Sci (China) 2014; 26:2266-2276. [PMID: 25458681 DOI: 10.1016/j.jes.2014.09.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Revised: 03/31/2014] [Accepted: 04/11/2014] [Indexed: 06/04/2023]
Abstract
The newly-developed cavity ring-down laser absorption spectroscopy analyzer with special calibration protocols has enabled the direct measurement of atmospheric vapor isotopes at high spatial and temporal resolution. This paper presents real-time hydrogen and oxygen stable isotope data for atmospheric water vapor above the sea surface, over a wide range of latitudes spanning from 38°N to 69°S. Our results showed relatively higher values of δ(18)O and δ(2)H in the subtropical regions than those in the tropical and high latitude regions, and also a notable decreasing trend in the Antarctic coastal region. By combining the hydrogen and oxygen isotope data with meteoric water line and backward trajectory model analysis, we explored the kinetic fractionation caused by subsiding air masses and related saturated vapor pressure in the subtropics, and the evaporation-driven kinetic fractionation in the Antarctic region. Simultaneous observations of meteorological and marine variables were used to interpret the isotopic composition characteristics and influential factors, indicating that d-excess is negatively correlated with humidity across a wide range of latitudes and weather conditions worldwide. Coincident with previous studies, d-excess is also positively correlated with sea surface temperature and air temperature (Tair), with greater sensitivity to Tair. Thus, atmospheric vapor isotopes measured with high accuracy and good spatial-temporal resolution could act as informative tracers for exploring the water cycle at different regional scales. Such monitoring efforts should be undertaken over a longer time period and in different regions of the world.
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Affiliation(s)
- Jingfeng Liu
- State Key Laboratory of Cryospheric Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Cunde Xiao
- State Key Laboratory of Cryospheric Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China; Chinese Academy of Meteorological Sciences, Beijing 100081, China
| | - Minghu Ding
- State Key Laboratory of Cryospheric Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China; Chinese Academy of Meteorological Sciences, Beijing 100081, China
| | - Jiawen Ren
- State Key Laboratory of Cryospheric Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China
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Dubbert M, Cuntz M, Piayda A, Werner C. Oxygen isotope signatures of transpired water vapor: the role of isotopic non-steady-state transpiration under natural conditions. THE NEW PHYTOLOGIST 2014; 203:1242-1252. [PMID: 24909361 DOI: 10.1111/nph.12878] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Accepted: 05/06/2014] [Indexed: 05/20/2023]
Abstract
The oxygen isotope signature of water is a powerful tracer of water movement from plants to the global scale. However, little is known about the short-term variability of oxygen isotopes leaving the ecosystem via transpiration, as high-frequency measurements are lacking. A laser spectrometer was coupled to a gas-exchange chamber directly estimating branch-level fluxes in order to evaluate the short-term variability of the isotopic composition of transpiration (δE ) and to investigate the role of isotopic non-steady-state transpiration under natural conditions in cork-oak trees (Quercus suber) during distinct Mediterranean seasons. The measured δ(18) O of transpiration (δE ) deviated from isotopic steady state throughout most of the day even when leaf water at the evaporating sites was near isotopic steady state. High agreement was found between estimated and modeled δE values assuming non-steady-state enrichment of leaf water. Isoforcing, that is, the influence of the transpirational δ(18) O flux on atmospheric values, deviated from steady-state calculations but daily means were similar between steady state and non-steady state. However, strong daytime isoforcing on the atmosphere implies that short-term variations in δE are likely to have consequences for large-scale applications, for example, partitioning of ecosystem fluxes or satellite-based applications.
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Affiliation(s)
- Maren Dubbert
- Agroecosystem Research, BAYCEER, University of Bayreuth, Universitätsstraße 30, 95447, Bayreuth, Germany
| | - Matthias Cuntz
- UFZ - Computational Hydrosystems, Helmholtz Centre for Environmental Research, Permoserstraße 15, 04318, Leipzig, Germany
| | - Arndt Piayda
- UFZ - Computational Hydrosystems, Helmholtz Centre for Environmental Research, Permoserstraße 15, 04318, Leipzig, Germany
| | - Christiane Werner
- Agroecosystem Research, BAYCEER, University of Bayreuth, Universitätsstraße 30, 95447, Bayreuth, Germany
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Yamamoto A, Uchida Y, Akiyama H, Nakajima Y. Continuous and unattended measurements of the site preference of nitrous oxide emitted from an agricultural soil using quantum cascade laser spectrometry with intercomparison with isotope ratio mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2014; 28:1444-1452. [PMID: 24861593 DOI: 10.1002/rcm.6916] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Revised: 04/02/2014] [Accepted: 04/03/2014] [Indexed: 06/03/2023]
Abstract
RATIONALE The difference between the (15)N natural abundance of (14)N-(15)N-O and (15)N-(14)N-O (site preference; SP) is used to understand the mechanisms underlying N2O emissions from soils. We investigated the use of quantum cascade laser (QCL) absorption spectrometry for continuous and precise analysis of the SP of N2O emitted from a field soil at atmospheric mixing ratios. METHODS A QCL-based spectrometer was used to determine the SP of soil-emitted N2O accumulated in a closed chamber system without preconcentration. N2O standards (<2500 ppbv) were used to evaluate the precision of the QCL spectrometry (QCLS) system. CO2 and H2O were removed from the gas samples. Intercomparison measurements of QCLS and isotope ratio mass spectrometry (IRMS) were performed on N2O calibration gases at different mixing ratios. The observed dependency of the QCLS result on the N2O mixing ratio was corrected. RESULTS Measurement of SP of N2O emitted from the field suggested that the SP of N2O varied from 0 to 40‰ over a period of 1 month. The precisions of the SP measurements (300-2500 ppbv) were <1.9‰ for δ(15)N(α) values, <2.6‰ for δ(15)N(β) values, <2.1‰ for δ(15)N(bulk) values, and <2.1‰ for the SP (1 min averaging time) obtained on a once-an-hour calibrated QCLS system, with a cell temperature control precision of ±0.01 K. CONCLUSIONS Continuous and unattended measurements of the SP of N2O emitted from soils were achieved at low N2O mixing ratios. The accuracy of the QCLS measurements for the SP of N2O was significantly improved by precisely controlling the temperature of the system and by correcting for the concentration dependency of the raw data through an intercomparison with IRMS measurements.
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Affiliation(s)
- Akinori Yamamoto
- National Institute for Agro-Environmental Sciences, 3-1-3 Kannondai, Tsukuba, Ibaraki, 305-8604, Japan
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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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Simonin KA, Roddy AB, Link P, Apodaca R, Tu KP, Hu J, Dawson TE, Barbour MM. Isotopic composition of transpiration and rates of change in leaf water isotopologue storage in response to environmental variables. PLANT, CELL & ENVIRONMENT 2013; 36:2190-206. [PMID: 23647101 DOI: 10.1111/pce.12129] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Revised: 04/18/2013] [Accepted: 04/22/2013] [Indexed: 05/27/2023]
Abstract
During daylight hours, the isotope composition of leaf water generally approximates steady-state leaf water isotope enrichment model predictions. However, until very recently there was little direct confirmation that isotopic steady-state (ISS) transpiration in fact exists. Using isotope ratio infrared spectroscopy (IRIS) and leaf gas exchange systems we evaluated the isotope composition of transpiration and the rate of change in leaf water isotopologue storage (isostorage) when leaves were exposed to variable environments. In doing so, we developed a method for controlling the absolute humidity entering the gas exchange cuvette for a wide range of concentrations without changing the isotope composition of water vapour. The measurement system allowed estimation of (18)O enrichment both at the evaporation site and for bulk leaf water, in the steady state and the non-steady state. We show that non-steady-state effects dominate the transpiration isoflux even when leaves are at physiological steady state. Our results suggest that a variable environment likely prevents ISS transpiration from being achieved and that this effect may be exacerbated by lengthy leaf water turnover times due to high leaf water contents.
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Affiliation(s)
- Kevin A Simonin
- Faculty of Agriculture and Environment, University of Sydney, Sydney, NSW, 2570, Australia
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Wassenaar LI, Ahmad M, Aggarwal P, van Duren M, Pöltenstein L, Araguas L, Kurttas T. Worldwide proficiency test for routine analysis of δ2H and δ18O in water by isotope-ratio mass spectrometry and laser absorption spectroscopy. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2012; 26:1641-1648. [PMID: 22730085 DOI: 10.1002/rcm.6270] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
RATIONALE The interpretation of stable hydrogen and oxygen isotope data in isotope hydrology relies on accurate, high-precision analytical measurements of the (2)H:(1)H and (18)O:(16)O ratios in liquid H(2)O samples. METHODS A synthesis of the International Atomic Energy Agency (IAEA) worldwide proficiency test for analytical laboratories conducting routine analysis of δ(2)H and δ(18)O values in water (WICO2011) by isotope-ratio mass spectrometry (IRMS) and laser absorption spectroscopy (LAS) technology has been carried out. RESULTS This test revealed that >96% of the 160 laboratory submissions provided acceptable results within ±2‰ for δ(2) H values and ±0.2‰ for δ(18)O values of the established reference values for four test waters, and no difference in outcomes based on IRMS vs. LAS technology was found for good performing laboratories. CONCLUSIONS The leading cause of outliers appeared to be improper calibration or compromised storage of laboratory standard and primary reference waters; hence the importance of judicious storage of lab standards cannot be understated. The deprecated practice of single standard normalization was identified as a problem for some laboratories. We further recommend that laboratories strive to report parsimonious long-term precisions based upon control standards, and to improve quantification and correction for LAS instrumental drift and inter-sample carryover effects.
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Affiliation(s)
- L I Wassenaar
- International Atomic Energy Agency, Isotope Hydrology Section, Division of Physical and Chemical Sciences, Vienna International Centre, P.O. Box 100, 1400 Vienna, Austria.
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Koehler G, Wassenaar LI. Determination of the Hydrogen Isotopic Compositions of Organic Materials and Hydrous Minerals Using Thermal Combustion Laser Spectroscopy. Anal Chem 2012; 84:3640-5. [PMID: 22432837 DOI: 10.1021/ac3000489] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Geoff Koehler
- Environment Canada, 11 Innovation Boulevard, Saskatoon, SK, Canada, S7N 3H5
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Schmidt M, Maseyk K, Lett C, Biron P, Richard P, Bariac T, Seibt U. Reducing and correcting for contamination of ecosystem water stable isotopes measured by isotope ratio infrared spectroscopy. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2012; 26:141-153. [PMID: 22173802 DOI: 10.1002/rcm.5317] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Concern exists about the suitability of laser spectroscopic instruments for the measurement of the (18)O/(16)O and (2)H/(1)H values of liquid samples other than pure water. It is possible to derive erroneous isotope values due to optical interference by certain organic compounds, including some commonly present in ecosystem-derived samples such as leaf or soil waters. Here we investigated the reliability of wavelength-scanned cavity ring-down spectroscopy (CRDS) (18)O/(16)O and (2)H/(1)H measurements from a range of ecosystem-derived waters, through comparison with isotope ratio mass spectrometry (IRMS). We tested the residual of the spectral fit S(r) calculated by the CRDS instrument as a means to quantify the difference between the CRDS and IRMS δ-values. There was very good overall agreement between the CRDS and IRMS values for both isotopes, but differences of up to 2.3‰ (δ(18)O values) and 23‰ (δ(2)H values) were observed in leaf water extracts from Citrus limon and Alnus cordata. The S(r) statistic successfully detected contaminated samples. Treatment of Citrus leaf water with activated charcoal reduced, but did not eliminate, δ(2)H(CRDS) - δ(2)H(IRMS) linearly for the tested range of 0-20% charcoal. The effect of distillation temperature on the degree of contamination was large, particularly for δ(2)H values but variable, resulting in positive, negative or no correlation with distillation temperature. S(r) and δ(CRDS) - δ(IRMS) were highly correlated, in particular for δ(2)H values, across the range of samples that we tested, indicating the potential to use this relationship to correct the δ-values of contaminated plant water extracts. We also examined the sensitivity of the CRDS system to changes in the temperature of its operating environment. We found that temperature changes ≥4 °C for δ(18)O values and ≥10 °C for δ(2)H values resulted in errors larger than the CRDS precision for the respective isotopes and advise the use of such instruments only in sufficiently temperature-stabilised environments.
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Affiliation(s)
- Markus Schmidt
- BIOEMCO (UMR 7618: UPMC-Paris 6, INRA, CNRS, ENS, AgroParisTech, IRD, Paris 12), Campus AgroParisTech, Bâtiment EGER, 78850 Thiverval-Grignon, France.
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Munksgaard NC, Wurster CM, Bird MI. Continuous analysis of δ¹⁸O and δD values of water by diffusion sampling cavity ring-down spectrometry: a novel sampling device for unattended field monitoring of precipitation, ground and surface waters. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2011; 25:3706-3712. [PMID: 22468325 DOI: 10.1002/rcm.5282] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A novel sampling device suitable for continuous, unattended field monitoring of rapid isotopic changes in environmental waters is described. The device utilises diffusion through porous PTFE tubing to deliver water vapour continuously from a liquid water source for analysis of δ¹⁸O and δD values by Cavity Ring-Down Spectrometry (CRDS). Separation of the analysed water vapour from non-volatile dissolved and particulate contaminants in the liquid sample minimises spectral interferences associated with CRDS analyses of many aqueous samples. Comparison of isotopic data for a range of water samples analysed by Diffusion Sampling-CRDS (DS-CRDS) and Isotope Ratio Mass Spectrometry (IRMS) shows significant linear correlations between the two methods allowing for accurate standardisation of DS-CRDS data. The internal precision for an integration period of 3 min (standard deviation (SD) = 0.1‰ and 0.3‰ for δ¹⁸O and δD values, respectively) is similar to analysis of water by CRDS using an autosampler to inject and evaporate discrete water samples. The isotopic effects of variable air temperature, water vapour concentration, water pumping rate and dissolved organic content were found to be either negligible or correctable by analysis of water standards. The DS-CRDS system was used to analyse the O and H isotope composition in short-lived rain events. Other applications where finely time resolved water isotope data may be of benefit include recharge/discharge in groundwater/river systems and infiltration-related changes in cave drip water.
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Affiliation(s)
- Niels C Munksgaard
- James Cook University, Earth and Environmental Sciences, Cairns, Queensland, Australia.
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Tremoy G, Vimeux F, Cattani O, Mayaki S, Souley I, Favreau G. Measurements of water vapor isotope ratios with wavelength-scanned cavity ring-down spectroscopy technology: new insights and important caveats for deuterium excess measurements in tropical areas in comparison with isotope-ratio mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2011; 25:3469-3480. [PMID: 22095494 DOI: 10.1002/rcm.5252] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The new infrared laser spectroscopic techniques enable us to measure the isotopic composition (δ(18)O and δ(2)H) of atmospheric water vapor. With the objective of monitoring the isotopic composition of tropical water vapor (West Africa, South America), and to discuss deuterium excess variability (d=δ(2)H - 8δ(18)O) with an accuracy similar to measurements arising from isotope-ratio mass spectrometry (IRMS), we have conducted a number of tests and calibrations using a wavelength-scanned cavity ring-down spectroscopy (WS-CRDS) technique. We focus in this paper on four main aspects regarding (1) the tubing material, (2) the humidity calibration of the instrument, (3) the water vapor concentration effects on δ, and (4) the isotopic calibration of the instrument. First, we show that Synflex tubing strongly affects δ(2)H measurements and thus leads to unusable d values. Second, we show that the mixing ratio as measured by WS-CRDS has to be calibrated versus atmospheric mixing ratio measurements and we also suggest possible non-linear effects over the whole mixing ratio range (~2 to 20 g/kg). Third, we show that significant non-linear effects are induced by water vapor concentration variations on δ measurements, especially for mixing ratios lower than ~5 g/kg. This effect induces a 5 to 10‰ error in deuterium excess and is instrument-dependent. Finally, we show that an isotopic calibration (comparison between measured and true values of isotopic water standards) is needed to avoid errors on deuterium excess that can attain ~10‰.
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Affiliation(s)
- Guillaume Tremoy
- Institut Pierre Simon Laplace (IPSL), Laboratoire des Sciences du Climat et de l'Environnement (LSCE), UMR 8212 (CEA-CNRS-UVSQ), CE Saclay, Orme des Merisiers, Bât. 701, 91191 Gif-sur-Yvette, Cedex, France.
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Johnson LR, Sharp ZD, Galewsky J, Strong M, Van Pelt AD, Dong F, Noone D. Hydrogen isotope correction for laser instrument measurement bias at low water vapor concentration using conventional isotope analyses: application to measurements from Mauna Loa Observatory, Hawaii. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2011; 25:608-616. [PMID: 21290447 DOI: 10.1002/rcm.4894] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The hydrogen and oxygen isotope ratios of water vapor can be measured with commercially available laser spectroscopy analyzers in real time. Operation of the laser systems in relatively dry air is difficult because measurements are non-linear as a function of humidity at low water concentrations. Here we use field-based sampling coupled with traditional mass spectrometry techniques for assessing linearity and calibrating laser spectroscopy systems at low water vapor concentrations. Air samples are collected in an evacuated 2 L glass flask and the water is separated from the non-condensable gases cryogenically. Approximately 2 µL of water are reduced to H(2) gas and measured on an isotope ratio mass spectrometer. In a field experiment at the Mauna Loa Observatory (MLO), we ran Picarro and Los Gatos Research (LGR) laser analyzers for a period of 25 days in addition to periodic sample collection in evacuated flasks. When the two laser systems are corrected to the flask data, they are strongly coincident over the entire 25 days. The δ(2)H values were found to change by over 200‰ over 2.5 min as the boundary layer elevation changed relative to MLO. The δ(2)H values ranged from -106 to -332‰, and the δ(18)O values (uncorrected) ranged from -12 to -50‰. Raw data from laser analyzers in environments with low water vapor concentrations can be normalized to the international V-SMOW scale by calibration to the flask data measured conventionally. Bias correction is especially critical for the accurate determination of deuterium excess in dry air.
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Affiliation(s)
- L R Johnson
- Department of Earth and Planetary Sciences, MSCO, University of New Mexico, Albuquerque, 87131-0001, USA.
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