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GeoZentrum Nordbayern, Applied Geosciences, Friedrich-Alexander-University Erlangen-Nuremberg, Schlossgarten 5, 91054 Erlangen, Germany
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- PublicationRestrictedStable carbon isotope analysis of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) in natural waters – Results from a worldwide pro!ciency test(2013-06-21)
; ; ; ; ; ; ; ;van Geldern, R.; GeoZentrum Nordbayern, Applied Geosciences, Friedrich-Alexander-University Erlangen-Nuremberg, Schlossgarten 5, 91054 Erlangen, Germany ;Verma, M. P.; Geotermia, Instituto de Investigaciones Eléctricas, Reforma 113, Col. Palmira, Cuernavaca, Mor. C.P. 62490, Mexico ;Carvalho, M. C.; Centre for Coastal Biogeochemistry Research, Southern Cross University, Lismore 2480, NSW, Australia ;Grassa, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia ;Delgado-Huertas, A.; Laboratorio de Biogeoquímica de Isótopos Estables, Instituto Andaluz de Ciencias de la Tierra IACT(CSIC-UGR), Avda. de las Palmeras 4, 18100 Armilla, Granada, Spain ;Monvoisin, G.; Laboratoire Interactions et Dynamiques des Environnements de Surface, Bâtiment 504, Université Paris Sud, 91405 Orsay, France ;Barth, J. A. C.; GeoZentrum Nordbayern, Applied Geosciences, Friedrich-Alexander-University Erlangen-Nuremberg, Schlossgarten 5, 91054 Erlangen, Germany; ; ; ; ; ; 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 !13C 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 !13CDIC and !13CDOC values by !ve laboratories with isotope ratio mass spectrometry (IRMS) in an international pro!ciency test. RESULTS: The reported !13CDIC 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). !13CDOC values were only comparable for seawater and showed differences of 10 to 21‰for other samples. CONCLUSIONS: This study indicates that scatter in !13CDIC 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 speci!c 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.283 41 - PublicationRestrictedInter-laboratory test for oxygen and hydrogen stable isotope analyses of geothermal fluids: Assessment of reservoir fluid compositions(2018-10-30)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;; ; ; ; ; ; ;Knowledge of the accuracy and precision for oxygen (δ18 O values) and hydrogen (δ2 H values) stable isotope analyses of geothermal fluid samples is important to understand geothermal reservoir processes, such as partial boiling-condensation and encroachment of cold and reinjected waters. The challenging aspects of the analytical techniques for this specific matrix include memory effects and higher scatter of delta values with increasing total dissolved solids (TDS) concentrations, deterioration of Pt-catalysts by dissolved/gaseous H2 S for hydrogen isotope equilibration measurements and isotope salt effects that offset isotope ratios determined by gas equilibration techniques.92 1 - PublicationOpen AccessInterlaboratory test for chemical analysis of geothermal fluids: A new approach to determine deep geothermal reservoir fluid composition with uncertainty propagation(2022)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; A representative fluid sampling of surface geothermal manifestations and its analytical data quality assurance and quality control (QA/QC) are challenging aspects of understanding the geothermal reservoir processes. To achieve these goals, an interlaboratory test for the chemical analyses of ten water samples: one synthetic water, two lake waters (i.e., duplicated), one stream water, and six water samples from two geothermal wells of Los Azufres Geothermal field (LAGF), Michoacan, Mexico, was conducted. The geothermal wells were sampled at four points: (1) total discharge of condensed fluid at the wellhead, (2) separate liquid condensed in the well separator, (3) flushed liquid at the weir box, and (4) separated vapor condensed at the well-separator (data taken from Verma et al., 2022). Sixteen laboratories from ten countries reported their results. The pH, electrical conductivity, Ca2+, Li+, SO4 2 B, and Si-total measurements were 8.35 ± 0.04, 12.25 ± 0.53 mS/cm, 25 ± 1 mg/l, 18 ± 1 mg/l, 569 ± 33 mg/l, 320 ± 21 mg/l, and 20.5 ± 0.7 mg/l, which are close to the conventional true values, 8.40, 12.31 mS/cm, 23 mg/l, 19 mg/l, 647 mg/l, 330 mg/l, and 20.0 mg/l, respectively. Analytical errors for major ions, Na+, Cl130 125