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Spangenberg JE, Lantos I. Fingerprinting of monovarietal olive oils from Argentina and Uruguay via stable isotope, fatty acid profile, and chemometric analyses. Food Chem 2024; 449:139194. [PMID: 38574525 DOI: 10.1016/j.foodchem.2024.139194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Revised: 03/18/2024] [Accepted: 03/28/2024] [Indexed: 04/06/2024]
Abstract
Tracing methods of non-European EVOOs commercialized worldwide are becoming crucial for effective authenticity controls. Limited analytical studies of these oils are available on a global scale, similar to those of European EVOOs. We report for the first time the fatty acid concentrations, bulk-oil 2H/1H, 13C/12C, and 18O/16O ratios and fatty acid 13C/12C ratios of 43 authentic monovarietal EVOOs from different geographical regions in Argentina and Uruguay. The samples were obtained from a wide range of latitudes and altitudes along an E-W profile, from lowlands near the Atlantic Ocean to the pre-Andean highlands near the Pacific Ocean. Principal component scores were used to cluster EVOOs into three groups- central-western Argentina, central Argentina, and Uruguay-based on nine stable isotope ratios and the oleic-linoleic acid concentration ratio. The bulk 2H/1H and 18O/16O values and 13C/12C of palmitoleic and linoleic acids provide good tools for differentiating these oils via linear discriminant analysis.
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Affiliation(s)
- Jorge Enrique Spangenberg
- Institute of Earth Surface Dynamics (IDYST), University of Lausanne, Geopolis Building, CH-1015 Lausanne, Switzerland.
| | - Irene Lantos
- Instituto de las Culturas (IDECU), Universidad de Buenos Aires & Consejo Nacional de Investigaciones Científicas y Técnicas, Moreno 350, C1091AAH Buenos Aires, Argentina
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Terzer-Wassmuth S, Araguás-Araguás LJ, Wassenaar LI, Stumpp C. Global and local meteoric water lines for δ 17O/δ 18O and the spatiotemporal distribution of Δ' 17O in Earth's precipitation. Sci Rep 2023; 13:19056. [PMID: 37925549 PMCID: PMC10625609 DOI: 10.1038/s41598-023-45920-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 10/25/2023] [Indexed: 11/06/2023] Open
Abstract
Recently, δ17O and its excess (Δ'17O) have become increasingly significant "triple-oxygen-isotope" indicators of distinctive hydrological processes in hydrology and climatology. This situation mirrors the research regarding δ18O and δ2H in the 1960s towards a solid theoretical base and a surge in application examples and field studies worldwide. Currently, systematic global measurements for δ17O in precipitation are still lacking. As a result, attempts have been made to define a Global δ17O/δ18O Meteoric Water Line (GMWL), often by using regional or local datasets of varying systematicity. Different definitions of the global reference slope (λref) for determining Δ'17O values have been proposed, by ongoing debate around a proposed consensus value of 0.528. This study used worldwide samples archived in the IAEA Global Network of Isotopes in Precipitation (GNIP) to (a) derive a δ17O/δ18O GMWL based on four-year monthly records from 66 GNIP stations, (b) formulate local δ17O/δ18O meteoric water lines (LMWL) for these stations' areas, and (c) evaluate regional and seasonal variations of Δ'17O in precipitation. The GMWL for δ17O/δ18O was determined to be δ'17O = 0.5280 ± 0.0002 δ'18O + 0.0153 ± 0.0013, in keeping with the consensus value. Furthermore, our results suggested that using a line-conditioned 17O-excess is a viable alternative over the global λref in the context of regional hydrology and paleoclimatology interpretations; however, without challenging the global λref as such.
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Affiliation(s)
- Stefan Terzer-Wassmuth
- International Atomic Energy Agency, Department of Nuclear Sciences and Applications, Division of Physical and Chemical Sciences, Isotope Hydrology Section, Vienna International Centre, PO Box 100, 1400, Vienna, Austria.
| | - Luis J Araguás-Araguás
- International Atomic Energy Agency, Department of Nuclear Sciences and Applications, Division of Physical and Chemical Sciences, Isotope Hydrology Section, Vienna International Centre, PO Box 100, 1400, Vienna, Austria
| | - Leonard I Wassenaar
- International Atomic Energy Agency, Department of Nuclear Sciences and Applications, Division of Physical and Chemical Sciences, Isotope Hydrology Section, Vienna International Centre, PO Box 100, 1400, Vienna, Austria
- WasserCluster Lunz Biologische Station GmbH, Dr. Carl Kupelwieser Promenade 5, 3293, Lunz Am See, Austria
| | - Christine Stumpp
- Department of Water, Atmosphere and Environment, Institute of Soil Physics and Rural Water Management, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, 1190, Vienna, Austria
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Keinan J, Goldsmith Y. A simple method for rapid removal of the memory effect in cavity ring-down spectroscopy water isotope measurements. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2023; 37:e9600. [PMID: 37698151 DOI: 10.1002/rcm.9600] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 06/09/2023] [Accepted: 06/22/2023] [Indexed: 09/13/2023]
Abstract
RATIONALE The accuracy determined in the routine analysis of water isotopes (δ17 O, δ18 O, δ2 H) using cavity ring-down spectroscopy is greatly affected by the memory effect (ME), a sample-to-sample carryover that biases measurements. This study aims to develop a simple method that rapidly removes the ME. METHODS We developed a method, designed for the Picarro L2140-i, that removes the ME by injecting small amounts of water with an extreme isotopic value ("kick") in the opposite direction of the ME. We conducted 11 experiments to identify the optimal kick for pairs of isotopically enriched and depleted samples. Once quantified, the optimal kick was used to create an ME-free, unbiased calibration curve, which was verified using international and internal lab standards. RESULTS Our kick method removes the ME very efficiently in half the time it takes for experiments without a kick. The optimal number of kick injections required to minimize stabilization time between standards of different compositions is three injections of δ2 H ≈ -1000‰ water per a 100‰ difference between standards. Three runs of routine measurements using the kick method resulted in uncertainties of 0.03‰, 0.2‰, and 5 permeg for δ18 O, δ2 H, and 17 O-excess, respectively. CONCLUSIONS This study demonstrates a new method for rapidly removing the ME. Our kick protocol is a readily available, cheap, and efficient approach to reduce instrumental bias and improve measurement accuracy.
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Affiliation(s)
- Jonathan Keinan
- Institute of Earth Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
- Geological Survey of Israel, Jerusalem, Israel
| | - Yonaton Goldsmith
- Institute of Earth Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
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Terzer-Wassmuth S, Wassenaar LI. Performance of low-cost stainless-steel beverage kegs for long-term storage integrity and easy dispensing of water isotope (δ 18 O, δ 2 H) reference materials. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2021; 35:e9164. [PMID: 34270817 DOI: 10.1002/rcm.9164] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 07/08/2021] [Accepted: 07/12/2021] [Indexed: 06/13/2023]
Abstract
RATIONALE A widespread problem observed in global water isotope (δ18 O, δ2 H) proficiency tests is compromised working reference materials due to storage-dispensing evaporation effects. Proper storage requires no evaporation or leakage, which causes isotopic drift and bias. Surveys by the International Atomic Energy Agency (IAEA) show most isotope laboratories use glass or plastic bottles to store working reference materials, with frequent opening and closings that pose evaporation risks. Practical small (ca. 2-5 L) storage-dispensing solutions free of air exposure, evaporation, and leakage are needed. We also tested several smaller-scale bottles for day-to-day aliquots. METHODS We tested low-cost, conveniently sized (4 L) adaptations of a common stainless-steel beverage keg with a liquid dispenser, with minor modifications to facilitate low-flow dispensing and pressurization (1-2 bar) with Ar or N2 . We tested three kegs (100%, 75%, 50% initial fills) for a 2-year period along with monthly dispensing to assess long-term storage viability for maintaining δ18 O and δ2 H integrity and dispensing, and day-to-day aliquot bottles for 6 months. RESULTS Test results showed these small keg storage systems fully maintained the isotopic integrity of water over the 2-year testing period with no trend in the isotopic data that would reveal evaporative loss or leakage (e.g., pressure or mass loss) regardless of starting fill level. However, evaporated water in the outlet tube assembly must be eliminated by discarding 15-20 mL before dispensing into appropriate daily-use laboratory standard bottles (30-100 mL). Glass bottles for daily aliquots showed good integrity properties, but only if their fill level was >50%. CONCLUSIONS The use of a low-cost pressurized metal beverage keg dispensing system provides a robust solution to enable laboratories to maintain the integrity of their water isotope working reference materials over several years.
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Affiliation(s)
- Stefan Terzer-Wassmuth
- Isotope Hydrology Section, Division of Physical and Chemical Sciences, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna International Centre, PO Box 100, Vienna, 1400, Austria
| | - Leonard I Wassenaar
- Isotope Hydrology Section, Division of Physical and Chemical Sciences, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna International Centre, PO Box 100, Vienna, 1400, Austria
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Böttcher ME, Schmiedinger I. The impact of temperature on the water isotope ( 2H/ 1H, 17O/ 16O, 18O/ 16O) fractionation upon transport through a low-density polyethylene membrane. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2021; 57:183-192. [PMID: 33241946 DOI: 10.1080/10256016.2020.1845668] [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: 07/13/2020] [Accepted: 09/13/2020] [Indexed: 06/11/2023]
Abstract
In the present study we investigated the isotope effects associated with water loss from closed low-density polyethylene (LDPE) bottles via diffusion at temperatures between 4 and 60 °C. While at low temperatures (4 and 10 °C) no substantial diffusional loss of water was observed within storage time, a pronounced loss was found for the experiments at room temperature and 60 °C. The latter was associated with a substantial increase in δ 18O, δ 17O, and δ 2Η values, and a decrease in the deuterium excess. The magnitude of the isotope effects essentially depended on the extent of water evaporation from the closed bottles through the LDPE membrane.
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Affiliation(s)
- Michael Ernst Böttcher
- Geochemistry and Isotope Biogeochemistry Group, Department Marine Geology, Leibniz Institute for Baltic Sea Research (IOW), Warnemünde, Germany
- Marine Geochemistry, University of Greifswald, Greifswald, Germany
- Interdisciplinary Faculty, Department of Maritime Systems, University of Rostock, Rostock, Germany
| | - Iris Schmiedinger
- Geochemistry and Isotope Biogeochemistry Group, Department Marine Geology, Leibniz Institute for Baltic Sea Research (IOW), Warnemünde, Germany
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Gibson J, Eby P, Stadnyk T, Holmes T, Birks S, Pietroniro A. Dataset of 18O and 2H in streamflow across Canada: A national resource for tracing water sources, water balance and predictive modelling. Data Brief 2021; 34:106723. [PMID: 33521176 PMCID: PMC7820383 DOI: 10.1016/j.dib.2021.106723] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 12/18/2020] [Accepted: 01/06/2021] [Indexed: 12/04/2022] Open
Abstract
Oxygen-18 and deuterium were measured in streamflow samples collected from 331 gauging stations across Canada during 2013 to 2019. This dataset includes 9206 isotopic analyses made on 4603 individual water samples, and an additional 1259 analysis repeats for quality assurance/quality control. We also include arithmetic and flow-weighted averages, and other basic statistics for stations where adequate data were available. Station data are provided including station code, name, province, latitude, longitude and drainage area. Flow data were extracted from the historical database of the Water Survey of Canada. Details on the preliminary application of these data are provided in "18O and 2H in streamflow across Canada" [1]. Overall, these data are expected to be useful when combined with precipitation datasets and analytical or numerical models for water resource management and planning, including tracing streamflow source, water balance, evapotranspiration partitioning, residence time analysis, and early detection of climate and land use changes in Canada.
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Affiliation(s)
- J.J. Gibson
- InnoTech Alberta, 3-4476 Markham Street, Victoria BC V8Z 7X8 Canada
- University of Victoria, Department of Geography, Victoria BC V8W 3R4 Canada
| | - P. Eby
- InnoTech Alberta, 3-4476 Markham Street, Victoria BC V8Z 7X8 Canada
| | - T.A. Stadnyk
- University of Calgary, Geography, 2500 University Drive NW, Calgary AB T2N 1N4 Canada
- University of Manitoba, Civil Engineering, Winnipeg MB R3T 5V6 Canada
| | - T. Holmes
- University of Calgary, Geography, 2500 University Drive NW, Calgary AB T2N 1N4 Canada
- University of Manitoba, Civil Engineering, Winnipeg MB R3T 5V6 Canada
| | - S.J. Birks
- University of Victoria, Department of Geography, Victoria BC V8W 3R4 Canada
- InnoTech Alberta, 3608 - 33 St NW Calgary, Alberta T2L 2A6 Canada
| | - A. Pietroniro
- National Hydrological Service, Meteorological Service of Canada, National Hydrology Research Centre, 11 Innovation Blvd., Saskatoon SK S7N 3H5 Canada
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Payler SJ, Biddle JF, Sherwood Lollar B, Fox-Powell MG, Edwards T, Ngwenya BT, Paling SM, Cockell CS. An Ionic Limit to Life in the Deep Subsurface. Front Microbiol 2019; 10:426. [PMID: 30915051 PMCID: PMC6422919 DOI: 10.3389/fmicb.2019.00426] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 02/19/2019] [Indexed: 11/18/2022] Open
Abstract
The physical and chemical factors that can limit or prevent microbial growth in the deep subsurface are not well defined. Brines from an evaporite sequence were sampled in the Boulby Mine, United Kingdom between 800 and 1300 m depth. Ionic, hydrogen and oxygen isotopic composition were used to identify two brine sources, an aquifer situated in strata overlying the mine, and another ambiguous source distinct from the regional groundwater. The ability of the brines to support microbial replication was tested with culturing experiments using a diversity of inocula. The examined brines were found to be permissive for growth, except one. Testing this brine's physicochemical properties showed it to have low water activity and to be chaotropic, which we attribute to the high concentration of magnesium and chloride ions. Metagenomic sequencing of the brines that supported growth showed their microbial communities to be similar to each other and comparable to those found in other hypersaline environments. These data show that solutions high in dissolved ions can shape the microbial diversity of the continental deep subsurface biosphere. Furthermore, under certain circumstances, complex brines can establish a hard limit to microbial replication in the deep biosphere, highlighting the potential for subsurface uninhabitable aqueous environments at depths far shallower than a geothermally-defined limit to life.
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Affiliation(s)
- Samuel J. Payler
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
| | - Jennifer F. Biddle
- College of Earth, Ocean, and Environment, University of Delaware, Lewes, DE, United States
| | | | - Mark G. Fox-Powell
- School of Earth and Environmental Sciences, University of St. Andrews, St. Andrews, United Kingdom
| | | | - Bryne T. Ngwenya
- School of Geosciences, Kings Buildings, University of Edinburgh, Edinburgh, United Kingdom
| | - Sean M. Paling
- Boulby Underground Science Facility, Science and Technology Facilities Council, Swindon, United Kingdom
| | - Charles S. Cockell
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
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Stanič TF, Miler M, Brenčič M, Gosar M. Calcite precipitates in Slovenian bottled waters. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2017; 24:14176-14189. [PMID: 28421519 DOI: 10.1007/s11356-017-9015-4] [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: 09/09/2016] [Accepted: 04/10/2017] [Indexed: 06/07/2023]
Abstract
Storage of bottled waters in varying ambient conditions affects its characteristics. Different storage conditions cause changes in the initial chemical composition of bottled water which lead to the occurrence of precipitates with various morphologies. In order to assess the relationship between water composition, storage conditions and precipitate morphology, a study of four brands of Slovenian bottled water stored in PET bottles was carried out. Chemical analyses of the main ions and measurements of the physical properties of water samples were performed before and after storage of water samples at different ambient conditions. SEM/EDS analysis of precipitates was performed after elapsed storage time. The results show that the presence of Mg2+, SO42-, SiO2, Al, Mn and other impurities such as K+, Na+, Ba and Sr in the water controlled precipitate morphology by inhibiting crystal growth and leading to elongated rhombohedral calcite crystal forms which exhibit furrowed surfaces and calcite rosettes. Different storage conditions, however, affected the number of crystallization nuclei and size of calcite crystals. Hollow calcite spheres composed of cleavage rhombohedrons formed in the water with variable storage conditions by a combination of evaporation and precipitation of water droplets during high temperatures or by the bubble templating method.
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Affiliation(s)
| | - Miloš Miler
- Geological Survey of Slovenia, Dimičeva ulica 14, SI-1000, Ljubljana, Slovenia
| | - Mihael Brenčič
- Geological Survey of Slovenia, Dimičeva ulica 14, SI-1000, Ljubljana, Slovenia
- Department of Geology, Faculty of Natural Sciences and Engineering, University of Ljubljana, Aškerčeva cesta 12, SI-1000, Ljubljana, Slovenia
| | - Mateja Gosar
- Geological Survey of Slovenia, Dimičeva ulica 14, SI-1000, Ljubljana, Slovenia
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Dominik J, Tagliapietra D, Bravo AG, Sigovini M, Spangenberg JE, Amouroux D, Zonta R. Mercury in the food chain of the Lagoon of Venice, Italy. MARINE POLLUTION BULLETIN 2014; 88:194-206. [PMID: 25287224 DOI: 10.1016/j.marpolbul.2014.09.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Revised: 09/03/2014] [Accepted: 09/06/2014] [Indexed: 06/03/2023]
Abstract
Sediments and biota samples were collected in a restricted area of the Lagoon of Venice and analysed for total mercury, monomethyl mercury (MMHg), and nitrogen and carbon isotopes. Results were used to examine mercury biomagnification in a complex food chain. Sedimentary organic matter (SOM) proved to be a major source of nutrients and mercury to primary consumers. Contrary to inorganic mercury, MMHg was strongly biomagnified along the food chain, although the lognormal relationship between MMHg and δ(15)N was less constrained than generally reported from lakes or coastal marine ecosystems. The relationship improved when logMMHg concentrations were plotted against trophic positions derived from baseline δ(15)N estimate for primary consumers. From the regression slope a mean MMHg trophic magnification factor of 10 was obtained. Filter-feeding benthic bivalves accumulated more MMHg than other primary consumers and were probably important in MMHg transfer from sediments to higher levels of the food chain.
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Affiliation(s)
- Janusz Dominik
- Istituto di Scienze Marine - Consiglio Nazionale delle Ricerche, Arsenale - Tesa 104, Castello 2737/F 30122 Venezia, Italy; Institute F.-A. Forel, Université de Genève, CP 416, 1290 Versoix, Switzerland.
| | - Davide Tagliapietra
- Istituto di Scienze Marine - Consiglio Nazionale delle Ricerche, Arsenale - Tesa 104, Castello 2737/F 30122 Venezia, Italy
| | - Andrea G Bravo
- Institute F.-A. Forel, Université de Genève, CP 416, 1290 Versoix, Switzerland
| | - Marco Sigovini
- Istituto di Scienze Marine - Consiglio Nazionale delle Ricerche, Arsenale - Tesa 104, Castello 2737/F 30122 Venezia, Italy
| | - Jorge E Spangenberg
- Institute of Earth Surface Dynamics, University of Lausanne, CH 1015 Lausanne, Switzerland
| | - David Amouroux
- IPREM-LCABIE, UMR 5254 CNRS - Université de Pau et des Pays de l'Adour, Hélioparc, 2 av P. Angot, 64053 Pau, France
| | - Roberto Zonta
- Istituto di Scienze Marine - Consiglio Nazionale delle Ricerche, Arsenale - Tesa 104, Castello 2737/F 30122 Venezia, Italy
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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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van Geldern R, Verma MP, Carvalho MC, Grassa F, Delgado-Huertas A, Monvoisin G, Barth JAC. Stable carbon isotope analysis of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) in natural waters--results from a worldwide proficiency test. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2013; 27:2099-2107. [PMID: 23943331 DOI: 10.1002/rcm.6665] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2013] [Revised: 05/23/2013] [Accepted: 06/21/2013] [Indexed: 06/02/2023]
Abstract
RATIONALE Stable carbon isotope ratios of dissolved inorganic (DIC) and organic carbon (DOC) are of particular interest in aquatic geochemistry. The precision for this type of analysis is typically reported in the range of 0.1‰ to 0.5‰. However, there is no published attempt that compares δ(13)C measurements of DIC and DOC among different laboratories for natural water samples. METHODS Five natural water samples (lake water, seawater, two geothermal waters, and petroleum well water) were analyzed for δ(13)CDIC and δ(13)CDOC values by five laboratories with isotope ratio mass spectrometry (IRMS) in an international proficiency test. RESULTS The reported δ(13)CDIC values for lake water and seawater showed fairly good agreement within a range of about 1‰, whereas geothermal and petroleum waters were characterized by much larger differences (up to 6.6‰ between laboratories). δ(13)CDOC values were only comparable for seawater and showed differences of 10 to 21‰ for other samples. CONCLUSIONS This study indicates that scatter in δ(13)CDIC isotope data can be in the range of several per mil for samples from extreme environments (geothermal waters) and may not yield reliable information with respect to dissolved carbon (petroleum wells). The analyses of lake water and seawater also revealed a larger than expected difference and researchers from various disciplines should be aware of this. Evaluation of analytical procedures of the participating laboratories indicated that the differences cannot be explained by analytical errors or different data normalization procedures and must be related to specific sample characteristics or secondary effects during sample storage and handling. Our results reveal the need for further research on sources of error and on method standardization.
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Affiliation(s)
- Robert van Geldern
- GeoZentrum Nordbayern, Applied Geosciences, Friedrich-Alexander-University Erlangen-Nuremberg, Schlossgarten 5, 91054, Erlangen, Germany.
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