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Dordoni M, Tittel J, Rosenlöcher Y, Rinke K, Barth JAC. Metabolic activity of Planktothrix rubescens and its consequences on oxygen dynamics in laboratory experiment: A stable isotope study. JOURNAL OF PHYCOLOGY 2024. [PMID: 38634250 DOI: 10.1111/jpy.13455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 01/21/2024] [Accepted: 03/08/2024] [Indexed: 04/19/2024]
Abstract
Fluctuations in dissolved oxygen (DO) contents in natural waters can become intense during cyanobacteria blooms. In a reconnaissance study, we investigated DO concentrations and stable isotope dynamics during a laboratory experiment with the cyanobacterium Planktothrix rubescens in order to obtain insights into primary production under specific conditions. This observation was extended to sub-daily timescales with alternating light and dark phases. Dissolved oxygen concentrations and its isotopes (δ18ODO) ranged from 0.02 to 0.06 mmol · L-1 and from +9.6‰ to +23.4‰. The δ18ODO proved to be more sensitive than concentration measurements in response to metabolic variation and registered earlier shifts to dominance by respiration. Oxygen (O2) contents in the headspace and its isotopes (δ18OO2) ranged from 2.62 to 3.20 mmol · L-1 and from +9.8‰ to +21.9‰. Headspace samples showed less fluctuations in concentration and isotope trends because aquatic processes were hardly able to alter signals once the gas had reached the headspace. Headspace δ18OO2 values were corrected for gas-water equilibration and were determined to be higher than the mean δ18OH2O of -8.7‰. This finding suggests that counteracting respiration was important even during the highest photosynthetic activity. Additionally, headspace analyses led to the definition of a fractionation factor for respiration (αR) of this cyanobacterium with a value of 0.980. This value confirms the one commonly used for cyanobacteria. Our findings may become important for the management of water bodies where decreases in DO are caused by cyanobacteria.
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Affiliation(s)
- Marlene Dordoni
- Department of Geography and Geosciences, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Jörg Tittel
- Helmholtz Centre for Environmental Research-UFZ, Magdeburg, Germany
| | | | - Karsten Rinke
- Helmholtz Centre for Environmental Research-UFZ, Magdeburg, Germany
| | - Johannes A C Barth
- Department of Geography and Geosciences, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
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2
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Soto DX, Araguás-Araguás LJ, Han LF, Wassenaar LI. Radiocarbon integrity of dissolved inorganic carbon (DIC) samples stored in plastic and glass bottles: implications for reliable groundwater age dating. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2024; 60:53-65. [PMID: 38092692 DOI: 10.1080/10256016.2023.2289962] [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: 05/16/2023] [Accepted: 11/10/2023] [Indexed: 02/01/2024]
Abstract
Various approaches based on the natural variations of carbon isotopes (14C and 13C) in dissolved inorganic carbon (DIC) are routinely used to study groundwater dynamics and to estimate recharge rates by deriving groundwater ages. However, differences in 14C activities in groundwater samples collected repeatedly from the same wells and discordantly young 14C groundwater ages compared to noble gases led some authors to question the validity of radiocarbon dating. Poor sampling protocols and storage effects (14C contamination) for radiocarbon analysis are a critical factor in explaining age determination discrepancies. We evaluated the impact of storage protocols on carbon isotope exchange with atmospheric carbon dioxide by comparing glass versus standard plastic field sampling bottles for various storage times before radiocarbon and 13C analyses. The 14C bias after 12 months in pre-evacuated glass vials was minimal and within analytical precision. However, storage of DIC samples in plastic sampling bottles led to marked changes in 14C and 13C contents (up to ∼15 pmC and ∼ 5 ‰, respectively, after 12 months), meaning contamination led to younger groundwater age estimations than it should have been. Protocols for sampling and storing DIC samples for radiocarbon using pre-evacuated glass bottles help avoid atmospheric 14CO2 contamination and microbial activity.
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Affiliation(s)
- David X Soto
- Isotope Hydrology Section, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna, Austria
- Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany
| | - Luis J Araguás-Araguás
- Isotope Hydrology Section, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna, Austria
| | - Liang-Feng Han
- Isotope Hydrology Section, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna, Austria
| | - Leonard I Wassenaar
- Isotope Hydrology Section, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna, Austria
- Wasser Cluster Lunz Biological Station, Lunz am See, Austria
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Dordoni M, Seewald M, Rinke K, Schmidmeier J, Barth JAC. Novel evaluations of sources and sinks of dissolved oxygen via stable isotopes in lentic water bodies. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 838:156541. [PMID: 35679920 DOI: 10.1016/j.scitotenv.2022.156541] [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: 04/14/2022] [Revised: 06/03/2022] [Accepted: 06/03/2022] [Indexed: 06/15/2023]
Abstract
Dissolved oxygen (DO) dynamics of a temperate drinking water reservoir in the Harz Mountains (Germany) were investigated over a time period of 18 months. Via depth profiles in a fortnightly sampling resolution we were able to trace DO and temperature dynamics including the formation and breakdown of a Metalimnetic Oxygen Minimum (MOM) by means of DO concentration, saturation patterns and stable isotope ratios of dissolved oxygen (expressed as δ18ODO). Over the evaluation period, 19.4 % of the samples collected had δ18ODO values compatible with atmospheric equilibration (+24.6 ‰ ± 0.4 ‰). With values smaller and larger than this threshold, the remaining δ18ODO values showed that 40.8 % of our samples were dominated by photosynthesis and 39.8 % by respiration. From December to April the reservoir was mixed and DO consumption by respiration exceeded production via photosynthesis. During stratification period, quantification of respiration/photosynthesis rates (R/P) confirmed the epilimnion as a photosynthetic (i.e. net-autotrophic) environment while the hypolimnion was heterotrophic and dominated by respiration at various degrees. Samples of the MOM zone showed the highest R/P ratios and had among the most positive δ18ODO signals caused by respiration. This study showed that combinations of DO concentrations and their isotope ratios are promising to quantify critical zones of respiration and photosynthesis in aquatic environments.
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Affiliation(s)
- Marlene Dordoni
- Department of Geography and Geosciences, GeoZentrum Nordbayern, Friedrich- Alexander-Universität Erlangen-Nürnberg (FAU), Schlossgarten 5, Erlangen 91054, Germany.
| | - Michael Seewald
- Helmholtz Centre for Environmental Research-UFZ, Brueckstrasse 3a, D-39114 Magdeburg, Germany
| | - Karsten Rinke
- Helmholtz Centre for Environmental Research-UFZ, Brueckstrasse 3a, D-39114 Magdeburg, Germany
| | - Jakob Schmidmeier
- Department of Geography and Geosciences, GeoZentrum Nordbayern, Friedrich- Alexander-Universität Erlangen-Nürnberg (FAU), Schlossgarten 5, Erlangen 91054, Germany
| | - Johannes A C Barth
- Department of Geography and Geosciences, GeoZentrum Nordbayern, Friedrich- Alexander-Universität Erlangen-Nürnberg (FAU), Schlossgarten 5, Erlangen 91054, Germany
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Managing argon interference during measurements of 18O/ 16O ratios in O 2 by continuous-flow isotope ratio mass spectrometry. Anal Bioanal Chem 2022; 414:6177-6186. [PMID: 35841416 PMCID: PMC9314310 DOI: 10.1007/s00216-022-04184-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 06/08/2022] [Accepted: 06/17/2022] [Indexed: 11/08/2022]
Abstract
Abstract Monitoring changes in stable oxygen isotope ratios in molecular oxygen allows for studying many fundamental processes in bio(geo)chemistry and environmental sciences. While the measurement of \documentclass[12pt]{minimal}
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\begin{document}$$^{18}$$\end{document}18O/\documentclass[12pt]{minimal}
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\begin{document}$$^{16}$$\end{document}16O ratios of \documentclass[12pt]{minimal}
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\begin{document}$$\mathrm {O}_{2}$$\end{document}O2 in gaseous samples can be carried out conveniently and from extracting moderately small aqueous samples for analyses by continuous-flow isotope ratio mass spectrometry (CF-IRMS), oxygen isotope signatures, \documentclass[12pt]{minimal}
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\begin{document}$$\updelta ^{18}$$\end{document}δ18O, could be overestimated by more than 6\documentclass[12pt]{minimal}
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\begin{document}$$\permille$$\end{document}‱ because of interferences from argon in air. Here, we systematically evaluated the extent of such Ar interferences on \documentclass[12pt]{minimal}
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\begin{document}$$^{18}$$\end{document}18O/\documentclass[12pt]{minimal}
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\begin{document}$$\mathrm {O}_{2}$$\end{document}O2 for measurements by gas chromatography/IRMS and GasBench/IRMS and propose simple instrumental modifications for improved Ar and \documentclass[12pt]{minimal}
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\begin{document}$$\mathrm {O}_{2}$$\end{document}O2 separation as well as post-measurement correction procedures for obtaining accurate \documentclass[12pt]{minimal}
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\begin{document}$$\updelta ^{18}$$\end{document}δ18O. We subsequently evaluated the consequences of Ar interferences for the quantification of O isotope fractionation in terms of isotope enrichment factors, \documentclass[12pt]{minimal}
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\begin{document}$$\upepsilon _{\mathrm {O}}$$\end{document}ϵO, and \documentclass[12pt]{minimal}
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\begin{document}$$^{18}$$\end{document}18O kinetic isotope effects (\documentclass[12pt]{minimal}
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\begin{document}$$^{18}$$\end{document}18O KIEs) in samples where \documentclass[12pt]{minimal}
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\begin{document}$$\mathrm {O}_{2}$$\end{document}O2 is consumed and Ar:\documentclass[12pt]{minimal}
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\begin{document}$$\mathrm {O}_{2}$$\end{document}O2 ratios increase steadily and substantially over the course of a reaction. We show that the extent of O isotope fractionation is overestimated only slightly and that this effect is typically smaller than uncertainties originating from the precision of \documentclass[12pt]{minimal}
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\begin{document}$$\updelta ^{18}$$\end{document}δ18O measurements and experimental variability. Ar interferences can become more relevant and bias \documentclass[12pt]{minimal}
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\begin{document}$$\upepsilon _{\mathrm {O}}$$\end{document}ϵO values by more than \documentclass[12pt]{minimal}
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\begin{document}$$2\permille$$\end{document}2‱ in aqueous samples where fractional \documentclass[12pt]{minimal}
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\begin{document}$$\mathrm {O}_{2}$$\end{document}O2 conversion exceeds 90%. Practically, however, such samples would typically contain less than 25 \documentclass[12pt]{minimal}
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\begin{document}$$\mathrm {O}_{2}$$\end{document}O2 at ambient temperature, an amount that is close to the method detection limit of \documentclass[12pt]{minimal}
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\begin{document}$$^{16}$$\end{document}16O ratio measurement by CF-IRMS. Graphical abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1007/s00216-022-04184-3.
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Piatka DR, Venkiteswaran JJ, Uniyal B, Kaule R, Gilfedder B, Barth JAC. Dissolved oxygen isotope modelling refines metabolic state estimates of stream ecosystems with different land use background. Sci Rep 2022; 12:10204. [PMID: 35715436 PMCID: PMC9205993 DOI: 10.1038/s41598-022-13219-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 05/18/2022] [Indexed: 11/12/2022] Open
Abstract
Dissolved oxygen (DO) is crucial for aerobic life in streams and rivers and mostly depends on photosynthesis (P), ecosystem respiration (R) and atmospheric gas exchange (G). However, climate and land use changes progressively disrupt metabolic balances in natural streams as sensitive reflectors of their catchments. Comprehensive methods for mapping fundamental ecosystem services become increasingly important in a rapidly changing environment. In this work we tested DO and its stable isotope (18O/16O) ratios as novel tools for the status of stream ecosystems. For this purpose, six diel sampling campaigns were performed at three low-order and mid-latitude European streams with different land use patterns. Modelling of diel DO and its stable isotopes combined with land use analyses showed lowest P rates at forested sites, with a minimum of 17.9 mg m−2 h−1. Due to high R rates between 230 and 341 mg m−2 h−1 five out of six study sites showed a general heterotrophic state with P:R:G ratios between 0.1:1.1:1 and 1:1.9:1. Only one site with agricultural and urban influences showed a high P rate of 417 mg m−2 h−1 with a P:R:G ratio of 1.9:1.5:1. Between all sites gross G rates varied between 148 and 298 mg m−2 h−1. In general, metabolic rates depend on the distance of sampling locations to river sources, light availability, nutrient concentrations and possible exchanges with groundwater. The presented modelling approach introduces a new and powerful tool to study effects of land use on stream health. Such approaches should be integrated into future ecological monitoring.
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Affiliation(s)
- David R Piatka
- Department of Geography and Geosciences, GeoZentrum Nordbayern, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schlossgarten 5, 91054, Erlangen, Germany. .,Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research (IMK-IFU), Kreuzeckbahnstr. 19, 82467, Garmisch-Partenkirchen, Germany.
| | - Jason J Venkiteswaran
- Department of Geography and Environmental Studies, Wilfrid Laurier University, 75 University Avenue West, Waterloo, ON, N2L 3C5, Canada
| | - Bhumika Uniyal
- Professorship of Ecological Services, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Universitaetsstr. 30, 95447, Bayreuth, Germany
| | - Robin Kaule
- Limnological Research Station, BayCEER, Department of Hydrology, University of Bayreuth, 95440, Bayreuth, Germany
| | - Benjamin Gilfedder
- Limnological Research Station, BayCEER, Department of Hydrology, University of Bayreuth, 95440, Bayreuth, Germany
| | - Johannes A C Barth
- Department of Geography and Geosciences, GeoZentrum Nordbayern, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schlossgarten 5, 91054, Erlangen, Germany
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Köhler I, Piatka D, Barth JAC, Martinez RE. Beware of effects on isotopes of dissolved oxygen during storage of natural iron-rich water samples: A technical note. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2021; 35:e9024. [PMID: 33305417 DOI: 10.1002/rcm.9024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 11/21/2020] [Accepted: 12/09/2020] [Indexed: 06/12/2023]
Abstract
RATIONALE Investigations of the isotope ratios of dissolved oxygen (δ18 ODO ) provide valuable information about the oxygen cycle in aquatic systems. However, oxidation of Fe(II) may change pristine δ18 ODO values during storage and can lead to a misinterpretation. We sampled an Fe(II)-rich spring system and measured δ18 ODO values at various time intervals in order to determine influences of Fe-oxidation. METHODS Water samples were collected from an Fe-rich spring and related stream and the δ18 ODO values were measured in fresh, 4- and 13-day-old samples with an isotope ratio mass spectrometer. Three replicates were measured for each sample with a 1σ of ± 0.2‰. On-site parameters and Fe(II) contents were also measured over the course of the spring system by multi-parameter probes and spectrophotometry. RESULTS The δ18 ODO values over the course of the spring system in fresh, 4- and 13-day-old samples revealed differences of up to 8‰. We explain this increase by the consumption of DO by Fe(II)-oxidation. After a flow length of 85 m the differences in δ18 ODO values between fresh and older samples decreased because most of the Fe(II) was consumed. CONCLUSIONS False interpretations of δ18 ODO values are possible if Fe-rich water samples are measured after too long storage, and we recommend measurement immediately after sampling.
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Affiliation(s)
- Inga Köhler
- Department of Geography and Geosciences, GeoZentrum Nordbayern, Friedrich-Alexander-University Erlangen-Nuremberg (FAU), Schlossgarten 5, Erlangen, 91054, Germany
| | - David Piatka
- Department of Geography and Geosciences, GeoZentrum Nordbayern, Friedrich-Alexander-University Erlangen-Nuremberg (FAU), Schlossgarten 5, Erlangen, 91054, Germany
| | - Johannes A C Barth
- Department of Geography and Geosciences, GeoZentrum Nordbayern, Friedrich-Alexander-University Erlangen-Nuremberg (FAU), Schlossgarten 5, Erlangen, 91054, Germany
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Romanelli A, Soto DX, Matiatos I, Martínez DE, Esquius S. A biological and nitrate isotopic assessment framework to understand eutrophication in aquatic ecosystems. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 715:136909. [PMID: 32018104 DOI: 10.1016/j.scitotenv.2020.136909] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 01/22/2020] [Accepted: 01/22/2020] [Indexed: 06/10/2023]
Abstract
Eutrophication is a globally significant challenge facing aquatic ecosystems, mostly associated with human induced enrichment of these ecosystems with nitrogen and phosphorus. Given the complexity of assigning eutrophication issues to local primary N sources in field-based studies, this paper proposes a multi-stable isotope and biological framework to track nitrogen biogeochemical transformations, inputs and fate of nitrate in groundwater-dependent shallow lakes. Three representative freshwater ecosystems from the Pampa Plain (Argentina), with different land uses and topographic features were selected. Groundwater (N = 24), lake (N = 29) and stream (N = 20) samples were collected for isotope (δ15N-NO3- and δ18O-NO3-, δ18O-H2O) and hydrogeochemical (major ions and nutrients) determinations, and in the case of surface water, also for biological determinations (chlorophyll-a, fecal coliforms and nitrifying bacteria abundance). Both chemical and isotopic characteristics clearly indicated that denitrification was limited in lakes and streams, while evidence of assimilation in shallow lakes was confirmed. The results suggested that groundwater denitrification plays a role in the nitrate concentration pattern observed in the Pampeano Aquifer. The proportional contribution of nitrate sources to the inflow streams for all years were estimated by using Bayesian isotope mixing models, being ammonium nitrified in the system from soil and fertilizers ~50 - 75 %, sewage/manure ~20 - 40 % and atmospheric deposition ~5 - 15 %. In this sense, agricultural practices seem to have a relevant role in the eutrophication and water quality deterioration for these watersheds. However, limnological, bacterial and algal variables, assessed simultaneously with isotopic tracers, indicated spatio-temporal differences within and between these aquatic ecosystems. In the case of Nahuel Rucá Lake, animal manure was a significant source of nitrogen pollution, in contrast to La Brava Lake. In Los Padres Lake, agricultural practices were considered the main sources of nitrate input to the ecosystem.
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Affiliation(s)
- Asunción Romanelli
- Instituto de Investigaciones Marinas y Costeras, Consejo Nacional de Investigaciones Científicas y Técnicas (UNMdP-CONICET), FCEyN, CC1260, 7600 Mar del Plata, Argentina; Instituto de Geología de Costas y del Cuaternario, Universidad Nacional de Mar del Plata-CIC, 3350 Funes St., Level 1, 7600 Mar del Plata, Argentina.
| | - David X Soto
- Department of Earth and Environmental Sciences, KU Leuven, B-3001 Leuven, Belgium; UK Centre for Ecology and Hydrology, Lancaster Environment Centre, Lancaster LA1 4AP, UK
| | - Ioannis Matiatos
- International Atomic Energy Agency, Vienna International Centre, 1400 Vienna, Austria
| | - Daniel E Martínez
- Instituto de Investigaciones Marinas y Costeras, Consejo Nacional de Investigaciones Científicas y Técnicas (UNMdP-CONICET), FCEyN, CC1260, 7600 Mar del Plata, Argentina; Instituto de Geología de Costas y del Cuaternario, Universidad Nacional de Mar del Plata-CIC, 3350 Funes St., Level 1, 7600 Mar del Plata, Argentina
| | - Soledad Esquius
- Instituto de Investigaciones Marinas y Costeras, Consejo Nacional de Investigaciones Científicas y Técnicas (UNMdP-CONICET), FCEyN, CC1260, 7600 Mar del Plata, Argentina
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8
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Haschke S, Mader M, Schlicht S, Roberts AM, Angeles-Boza AM, Barth JAC, Bachmann J. Direct oxygen isotope effect identifies the rate-determining step of electrocatalytic OER at an oxidic surface. Nat Commun 2018; 9:4565. [PMID: 30385759 PMCID: PMC6212532 DOI: 10.1038/s41467-018-07031-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 10/09/2018] [Indexed: 11/22/2022] Open
Abstract
Understanding the mechanism of water oxidation to dioxygen represents the bottleneck towards the design of efficient energy storage schemes based on water splitting. The investigation of kinetic isotope effects has long been established for mechanistic studies of various such reactions. However, so far natural isotope abundance determination of O2 produced at solid electrode surfaces has not been applied. Here, we demonstrate that such measurements are possible. Moreover, they are experimentally simple and sufficiently accurate to observe significant effects. Our measured kinetic isotope effects depend strongly on the electrode material and on the applied electrode potential. They suggest that in the case of iron oxide as the electrode material, the oxygen evolution reaction occurs via a rate-determining O−O bond formation via nucleophilic water attack on a ferryl unit. Understanding reaction mechanisms is crucial for catalyst design. Here, natural-abundance isotope quantifications of O2 yield mechanistically significant reaction kinetic isotope effects for water oxidation over metal oxide electrodes, the bottleneck step of water electrolysis.
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Affiliation(s)
- Sandra Haschke
- Department of Chemistry and Pharmacy, Chemistry of Thin Film Materials, Friedrich-Alexander-Universität Erlangen-Nürnberg, Cauerstr. 4, 91058, Erlangen, Germany
| | - Michael Mader
- Department für Geographie und Geowissenschaften, GeoZentrum NordBayern, Applied Geology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Schlossgarten 5, 91054, Erlangen, Germany
| | - Stefanie Schlicht
- Department of Chemistry and Pharmacy, Chemistry of Thin Film Materials, Friedrich-Alexander-Universität Erlangen-Nürnberg, Cauerstr. 4, 91058, Erlangen, Germany
| | - André M Roberts
- Department für Geographie und Geowissenschaften, GeoZentrum NordBayern, Applied Geology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Schlossgarten 5, 91054, Erlangen, Germany
| | - Alfredo M Angeles-Boza
- Department of Chemistry and Institute of Materials Science, University of Connecticut, 55 North Eagleville Rd., Storrs, CT, 06269, USA.
| | - Johannes A C Barth
- Department für Geographie und Geowissenschaften, GeoZentrum NordBayern, Applied Geology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Schlossgarten 5, 91054, Erlangen, Germany.
| | - Julien Bachmann
- Department of Chemistry and Pharmacy, Chemistry of Thin Film Materials, Friedrich-Alexander-Universität Erlangen-Nürnberg, Cauerstr. 4, 91058, Erlangen, Germany. .,Institute of Chemistry, Saint Petersburg State University, Universitetskii pr. 26, Saint Petersburg, Russian Federation, 198504.
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Mader M, Roberts AM, Porst D, Schmidt C, Trauth N, van Geldern R, Barth JAC. River recharge versus O 2 supply from the unsaturated zone in shallow riparian groundwater: A case study from the Selke River (Germany). THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 634:374-381. [PMID: 29627561 DOI: 10.1016/j.scitotenv.2018.03.230] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 03/19/2018] [Accepted: 03/20/2018] [Indexed: 06/08/2023]
Abstract
Besides gas-water-exchange in surface waters, respiratory consumption of dissolved oxygen (DO) in adjacent riparian groundwater may trigger the addition of so far hardly explored sources from the unsaturated zone. These processes also systematically influence stable isotope ratios of DO and were investigated together with Cl- as a conservative tracer for water mixing in a near-river riparian groundwater system. The study focused on a losing stream section of the Selke River at the foot of the Harz Mountains (Germany). The study area exposed steep DO gradients between the stream water and riparian groundwater between April 2016 and May 2017. Our results indicated dominant influences of microbial community respiration with observed DO concentration gradients. These observations can be explained by DO from the river that is subject to fractionation by microbial respiration with a typical fractionation factor (αr) of 0.982. However, with such respiration dominance, we expected a simultaneous enrichment of δ18ODO towards values that are more positive than the well-known atmospheric O2 signal of +23.9‰ versus the Vienna Standard Mean Ocean Water standard (VSMOW). Surprisingly, our measurements revealed much lower δ18ODO values between +22‰ and +18‰ in the near-river groundwater. Mass balance calculations revealed that the DO pool in the shallow and unconfined aquifer receives contributions of up to about 80% by diffusion of oxygen from the vadose zone with a distinctly lower isotope value than the one of the atmosphere. This finding about additional oxygen sources from the unsaturated zone has numerous ramifications for oxygen related processes in near-river environments including the oxidation of pollutants, nutrients and ecosystem health.
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Affiliation(s)
- Michael Mader
- GeoZentrum Nordbayern, Department of Geography and Geosciences, Friedrich-Alexander University Erlangen-Nuremberg, Schlossgarten 5, 91054 Erlangen, Germany.
| | - André M Roberts
- GeoZentrum Nordbayern, Department of Geography and Geosciences, Friedrich-Alexander University Erlangen-Nuremberg, Schlossgarten 5, 91054 Erlangen, Germany
| | - David Porst
- GeoZentrum Nordbayern, Department of Geography and Geosciences, Friedrich-Alexander University Erlangen-Nuremberg, Schlossgarten 5, 91054 Erlangen, Germany
| | - Christian Schmidt
- Department Hydrogeology, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, 04318 Leipzig, Germany
| | - Nico Trauth
- Department Hydrogeology, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, 04318 Leipzig, Germany
| | - Robert van Geldern
- GeoZentrum Nordbayern, Department of Geography and Geosciences, Friedrich-Alexander University Erlangen-Nuremberg, Schlossgarten 5, 91054 Erlangen, Germany
| | - Johannes A C Barth
- GeoZentrum Nordbayern, Department of Geography and Geosciences, Friedrich-Alexander University Erlangen-Nuremberg, Schlossgarten 5, 91054 Erlangen, Germany.
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10
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Mader M, Schwerna P, Buchholz R, van Geldern R, Barth JA. A new approach to quantify system efficiency with dissolved oxygen isotopes during engineered growth of Galdieria sulphuraria. ALGAL RES 2017. [DOI: 10.1016/j.algal.2017.07.026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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11
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Pati SG, Bolotin J, Brennwald MS, Kohler HPE, Werner RA, Hofstetter TB. Measurement of oxygen isotope ratios ((18)O/(16)O) of aqueous O2 in small samples by gas chromatography/isotope ratio mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2016; 30:684-690. [PMID: 26864520 DOI: 10.1002/rcm.7481] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 12/11/2015] [Accepted: 12/12/2015] [Indexed: 06/05/2023]
Abstract
RATIONALE Oxygen isotope fractionation of molecular O2 is an important process for the study of aerobic metabolism, photosynthesis, and formation of reactive oxygen species. The latter is of particular interest for investigating the mechanism of enzyme-catalyzed reactions, such as the oxygenation of organic pollutants, which is an important detoxification mechanism. METHODS We developed a simple method to measure the δ(18) O values of dissolved O2 in small samples using automated split injection for gas chromatography coupled to isotope ratio mass spectrometry (GC/IRMS). After creating a N2 headspace, the dissolved O2 partitions from aqueous solution to the headspace, from which it can be injected into the gas chromatograph. RESULTS In aqueous samples of 10 mL and in diluted air samples, we quantified the δ(18) O values at O2 concentrations of 16 μM and 86 μM, respectively. The chromatographic separation of O2 and N2 with a molecular sieve column made it possible to use N2 as the headspace gas for the extraction of dissolved O2 from water. We were therefore able to apply a rigorous δ(18) O blank correction for the quantification of (18) O/(16) O ratios in 20 nmol of injected O2 . CONCLUSIONS The successful quantification of (18) O-kinetic isotope effects associated with enzymatic and chemical reduction of dissolved O2 illustrates how the proposed method can be applied for studying enzymatic O2 activation mechanisms in a variety of (bio)chemical processes.
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Affiliation(s)
- Sarah G Pati
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, CH-8600, Dübendorf, Switzerland
- Institute of Biogeochemistry and Pollutant Dynamics (IBP), ETH Zürich, CH-8092, Zürich, Switzerland
| | - Jakov Bolotin
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, CH-8600, Dübendorf, Switzerland
| | - Matthias S Brennwald
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, CH-8600, Dübendorf, Switzerland
| | - Hans-Peter E Kohler
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, CH-8600, Dübendorf, Switzerland
- Institute of Biogeochemistry and Pollutant Dynamics (IBP), ETH Zürich, CH-8092, Zürich, Switzerland
| | - Roland A Werner
- Institute of Agricultural Sciences, ETH Zürich, CH-8092, Zürich, Switzerland
| | - Thomas B Hofstetter
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, CH-8600, Dübendorf, Switzerland
- Institute of Biogeochemistry and Pollutant Dynamics (IBP), ETH Zürich, CH-8092, Zürich, Switzerland
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12
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Soto DX, Wassenaar LI, Hobson KA. Stable hydrogen and oxygen isotopes in aquatic food webs are tracers of diet and provenance. Funct Ecol 2013. [DOI: 10.1111/1365-2435.12054] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- David X. Soto
- Environment Canada 11 Innovation Boulevard Saskatoon SK S7N 3H5 Canada
| | | | - Keith A. Hobson
- Environment Canada 11 Innovation Boulevard Saskatoon SK S7N 3H5 Canada
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13
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Barnette JE, Lott MJ, Howa JD, Podlesak DW, Ehleringer JR. Hydrogen and oxygen isotope values in hydrogen peroxide. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2011; 25:1422-1428. [PMID: 21504008 DOI: 10.1002/rcm.5004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Hydrogen peroxide (H(2)O(2)) is a widely used oxidizer with many commercial applications; unfortunately, it also has terrorist-related uses. We analyzed 97 hydrogen peroxide solutions representing four grades purchased across the United States and in Mexico. As expected, the range of hydrogen (δ(2)H, 230‰) and oxygen (δ(18)O, 24‰) isotope values of the H(2)O(2) solutions was large, reflecting the broad isotopic range of dilution waters. This resulted in predictable linear relationships of δ(2)H and δ(18)O values of H(2)O(2) solutions that were near parallel to the Meteoric Water Line (MWL), offset by the concentration of H(2)O(2) in the solution. By grade, dilute (3 to 35%) H(2)O(2) solutions were not statistically different in slope. Although the δ(2)H values of manufactured H(2)O(2) could be different from those of water, rapid H(2)O(2)-H(2)O exchange of H atoms eliminated any distinct isotope signal. We developed a method to measure the δ(18)O value of H(2)O(2) independent of dilution water by directly measuring O(2) gas generated from a catalase-induced disproportionation reaction. We predicted that the δ(18)O values of H(2)O(2) would be similar to that of atmospheric oxygen (+23.5‰), the predominant source of oxygen in the most common H(2)O(2) manufacturing process (median disproportionated δ(18)O=23.8‰). The predictable H-O relationships in H(2)O(2) solutions make it possible to distinguish commercial dilutions from clandestine concentration practices. Future applications of this work include synthesis studies that investigate the chemical link between H(2)O(2) reagents and peroxide-based explosive products, which may assist law enforcement in criminal investigations.
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Affiliation(s)
- Janet E Barnette
- IsoForensics Inc., 423 Wakara Way, Suite 205, Salt Lake City, UT 84108, USA.
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14
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Snider DM, Spoelstra J, Schiff SL, Venkiteswaran JJ. Stable oxygen isotope ratios of nitrate produced from nitrification: (18)O-labeled water incubations of agricultural and temperate forest soils. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2010; 44:5358-5364. [PMID: 20550183 DOI: 10.1021/es1002567] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
In many nitrate (NO(3)(-)) source partitioning studies, the delta(18)O value for NO(3)(-) produced from nitrification is often assumed to reflect the isotopic compositions of environmental water (H(2)O) and molecular oxygen (O(2)) in a 2:1 ratio. Most studies that have measured or observed this microbial endmember have found that the delta(18)O-NO(3)(-) was more positive (up to +15 per thousand higher) than the assumed value. Current understanding of the mechanism(s) responsible for this discrepancy is limited. Incubations of one temperate forest soil (organic) and two agricultural soils (mineral) were conducted with (18)O-labeled H(2)O to apportion the sources of oxygen in NO(3)(-) generated from nitrification. The NO(3)(-) produced in all soils had delta(18)O values that could not be explained by a simple endmember mixing ratio of 2:1. A more comprehensive model describing the formation of microbial NO(3)(-) was developed, which accounts for oxygen exchange between H(2)O and NO(2)(-), and includes terms for kinetic and equilibrium isotope effects. Oxygen isotope exchange (i.e., the fraction of NO(3)(-)-oxygen that originates from the abiotic exchange of H(2)O and NO(2)(-)) varied widely between the temperate forest soil (0.37) and the two agricultural soils (0.52 and 0.88). At present, the microbial endmember for nitrification cannot be successfully predicted.
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Affiliation(s)
- David M Snider
- Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, Ontario, Canada.
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15
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Dubois KD, Lee D, Veizer J. Isotopic constraints on alkalinity, dissolved organic carbon, and atmospheric carbon dioxide fluxes in the Mississippi River. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2009jg001102] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Kristal D. Dubois
- Ottawa-Carleton Geosciences Centre; University of Ottawa; Ottawa Ontario Canada
| | - Dongho Lee
- Ottawa-Carleton Geosciences Centre; University of Ottawa; Ottawa Ontario Canada
| | - Ján Veizer
- Ottawa-Carleton Geosciences Centre; University of Ottawa; Ottawa Ontario Canada
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16
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Moyes AB, Schauer AJ, Siegwolf RTW, Bowling DR. An injection method for measuring the carbon isotope content of soil carbon dioxide and soil respiration with a tunable diode laser absorption spectrometer. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2010; 24:894-900. [PMID: 20201033 DOI: 10.1002/rcm.4466] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We present a novel technique in which the carbon isotope ratio (delta(13)C) of soil CO(2) is measured from small gas samples (<5 mL) injected into a stream of CO(2)-free air flowing into a tunable diode laser absorption spectrometer (TDL). This new method extends the dynamic range of the TDL to measure CO(2) mole fractions ranging from ambient to pure CO(2), reduces the volume of sample required to a few mL, and does not require field deployment of the instrument. The measurement precision of samples stored for up to 60 days was 0.23 per thousand. The new TDL method was applied with a simple gas well sampling technique to obtain and measure gas samples from shallow soil depth increments for CO(2) mole fraction and delta(13)C analysis, and subsequent determination of the delta(13)C of soil-respired CO(2). The method was tested using an artificial soil system containing a controlled CO(2) source and compared with an independent method using the TDL and an open soil chamber. The profile and chamber estimates of delta(13)C of an artificially produced CO(2) flux were consistent and converged to the delta(13)C of the CO(2) source at steady state, indicating the accuracy of both methods under controlled conditions. The new TDL method, in which a small pulse of sample is measured on a carrier gas stream, is analogous for the TDL technique to the development of continuous-flow configurations for isotope ratio mass spectrometry. While the applications presented here are focused on soil CO(2), this new TDL method could be applied in a number of situations requiring measurement of delta(13)C of CO(2) in small gas samples with ambient to high CO(2) mole fractions.
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Affiliation(s)
- Andrew B Moyes
- Department of Biology, University of Utah, 257 South 1400 East, Salt Lake City, UT 84112, USA.
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17
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Trojanowska A, Lewicka-Szczebak D, Jedrysek MO, Kurasiewicz M, Wassenaar LI, Izydorczyk K. Diurnal variations in the photosynthesis-respiration activity of a cyanobacterial bloom in a freshwater dam reservoir: an isotopic study. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2008; 44:163-175. [PMID: 18569188 DOI: 10.1080/10256010802066240] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The stable isotopic analyses of molecular oxygen dissolved in water (delta18O(DO)) and dissolved inorganic carbon (delta13C(DIC)), supplemented with basic chemical measurements, have been carried out on a diurnal basis to better understand the dynamics of photosynthesis and respiration in freshwater systems. Our observations have been carried out in a lowland dam reservoir, the Sulejow Lake (central Poland), during the summer cyanobacterial bloom. All data obtained, isotopic, hydrochemical, and biological, show a high mutual consistency. Namely, the lowest delta18O(DO) values, obtained at 10:00 and 14:00 (16.0 and 15.5 per thousand, respectively), correspond to the highest amount of cyanobacterial cells observed (66 and 63 mg dm(-3), respectively), whereas the minimum delta13C(DIC) (-10.6 per thousand) obtained at 22:00 corresponds to the maximum content of organic matter (110 mg dm(-3)). This evidence suggests that isotopic assays of delta18O(DO) and delta13C(DIC) are a reliable tool for the quantitative study of biochemical processes in freshwater systems.
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Affiliation(s)
- Adriana Trojanowska
- Laboratory of Isotope Geology and Geoecology, Institute of Geological Sciences, Wrocław, Poland
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18
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Wassenaar LI, Hendry MJ. Dynamics and stable isotope composition of gaseous and dissolved oxygen. GROUND WATER 2007; 45:447-60. [PMID: 17600575 DOI: 10.1111/j.1745-6584.2007.00328.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
The vadose zone and ground water environments are a sink for atmospheric O(2). The pathways and rates of O(2) consumption are primarily related to the availability and rate of oxidation of key reductants (e.g., organics, sulfides), through a combination of biological or abiotic reactions. The range in delta(18)O of O(2) in the subsurface is large, from +20 per thousand to +39 per thousand (Vienna Standard Mean Ocean Water) in the vadose zone and from +12 per thousand to +46 per thousand in ground water. The aggregated O(2) isotope fractionation by consumption (alpha(k)) was found to range from 0.970 to 1.300 and 0.980 to 1.030 in vadose zones and aquifers, respectively. These data suggest the delta(18)O patterns in both unsaturated zones and aquifers can be attributed to microbially mediated reactions (alpha(k)= range from 0.975 to 1.000), but there are apparently other inverse isotope fractionating processes (alpha(k) > 1.000). Circumstantial evidence suggested O(2) processed during the sulfide oxidation and precipitation of Fe-oxyhydroxides process (or other unidentified processes) could be the cause of the significant (18)O depletions. Overall, delta(18)O data from vadose zones and ground water revealed that isotope fractionation by consumption of gaseous and dissolved O(2) in the subsurface and ground water environments is more complicated than what has classically been attributed solely to geomicrobial respiration. Given the questions and inexplicable data arising from this study, further detailed research on O(2) consuming processes in the Earth's subsurface and ground water is warranted.
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Affiliation(s)
- L I Wassenaar
- Environment Canada, 11 Innovation Boulevard, Saskatoon, Saskatchewan, Canada.
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19
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Venkiteswaran JJ, Wassenaar LI, Schiff SL. Dynamics of dissolved oxygen isotopic ratios: a transient model to quantify primary production, community respiration, and air-water exchange in aquatic ecosystems. Oecologia 2007; 153:385-98. [PMID: 17516090 DOI: 10.1007/s00442-007-0744-9] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2006] [Accepted: 03/27/2007] [Indexed: 10/23/2022]
Abstract
Dissolved O(2) is an important aquatic ecosystem health indicator. Metabolic and gas exchange (G) rates, which control O(2) concentration, are affected by nutrient loading and other environmental factors. Traditionally, aquatic metabolism has been reported as primary production:community respiration (P:R) ratios using diel measurements and interpretations of dissolved O(2) and/or CO(2) concentrations, and recently using stable isotopes (delta(18)O, Delta(17)O) and steady state assumptions. Aquatic ecosystems, such as rivers and ponds, are not at steady state and exhibit diel changes, so steady state approaches are often inappropriate. A dynamic O(2) stable isotope model (photosynthesis-respiration-gas exchange; PoRGy) is presented here, requiring a minimum of parameters to quantify daily averaged P, R, and G rates under transient field conditions. Unlike steady state approaches, PoRGy can address scenarios with 100% O(2) saturation but with delta(18)O-O(2) values that are not at air equilibrium. PoRGy successfully accounts for isotopic G when applied to an oxygen isotope equilibration laboratory experiment. PoRGy model results closely matched the diel O(2) and delta(18)O-O(2) data from three field sites with different P:R:G ratios and various P, R and G rates. PoRGy provides a new research tool to assess ecosystem health and to pose environmental impact-driven questions. Using daily averaged rates was successful and thus they can be used to compare ecosystems across seasons and landscapes.
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Affiliation(s)
- Jason J Venkiteswaran
- Department of Earth Sciences, University of Waterloo, 200 University Avenue W, Waterloo, ON N2L 3G1, Canada.
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20
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Parker SR, Poulson SR, Gammons CH, DeGrandpre MD. Biogeochemical controls on Diel cycling of stable isotopes of dissolved O2 and dissolved inorganic carbon in the Big Hole River, Montana. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2005; 39:7134-40. [PMID: 16201639 DOI: 10.1021/es0505595] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Rivers with high biological productivity typically show substantial increases in pH and dissolved oxygen (DO) concentration during the day and decreases at night, in response to changes in the relative rates of aquatic photosynthesis and respiration. These changes, coupled with temperature variations, may impart diel (24-h) fluctuations in the concentration of trace metals, nutrients, and other chemical species. A better understanding of diel processes in rivers is needed and will lead to improved methods of data collection for both monitoring and research purposes. Previous studies have used stable isotopes of dissolved oxygen (DO) and dissolved inorganic carbon (DIC) as tracers of geochemical and biological processes in streams, lakes, and marine systems. Although seasonal variation in 6180 of DO in rivers and lakes has been documented, no study has investigated diel changes in this parameter. Here, we demonstrate large (up to 13%o) cycles in delta18O-DO for two late summer sampling periods in the Big Hole River of southwest Montana and illustrate that these changes are correlated to variations in the DO concentration, the C-isotopic composition of DIC, and the primary productivity of the system. The magnitude of the diel cycle in delta18O-DO was greater in August versus September because of the longer photoperiod and warmer water temperatures. This study provides another biogeochemical tool for investigating the O2 and C budgets in rivers and may also be applicable to lake and groundwater systems.
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Affiliation(s)
- Stephen R Parker
- Department of Chemistry and Geochemistry, Montana Tech of The University of Montana, Butte, Montana, USA.
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21
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Yun M, Mayer B, Taylor SW. delta34S measurements on organic materials by continuous flow isotope ratio mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2005; 19:1429-36. [PMID: 15880637 DOI: 10.1002/rcm.1939] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Sulfur (S) isotope ratios of thoroughly dried organic samples were measured by direct thermal decomposition in an elemental analyzer coupled to an isotope ratio mass spectrometer in continuous flow mode (EA-CF-IRMS). For organic samples of up to 13 mg weight and with total S contents of more than 10 microg, the reproducibility of the delta34S(organic) values was +/-0.4 per thousand or better. However, the delta34S values of organic samples measured directly by online EA-CF-IRMS analysis were between 0.3 and 2.9 per thousand higher than those determined on BaSO4 precipitates produced by Parr Bomb oxidation from the same sample material. Our results suggest that structural oxygen in organic samples influences the oxygen isotope ratios of the SO2 produced from organic samples. Consequently, SO2 generated from organic samples appears to have different 18O/16O ratios than SO2 generated from BaSO4 precipitates and inorganic reference materials, resulting in a deviation from the true delta34S values because of 32S16O18O contributions to mass 66. It was shown that both the amount of structural oxygen in the organic sample, and the difference of the oxygen isotope ratios between organic samples and tank O2, influenced the magnitude of the observed deviation from the true delta34S value after direct EA-CF-IRMS analysis of organic samples. Suggestions are made to correct the difference between measured delta34S(organic) and true delta34S values in order to obtain not only reproducible, but also accurate S isotope ratios for organic materials by EA-CF-IRMS.
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Affiliation(s)
- Misuk Yun
- Department of Geology & Geophysics, University of Calgary, 2500 University Dr. NW, Calgary, Alberta, Canada T2N 1N4
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22
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Sarma VVSS, Abe O, Saino T. Chromatographic Separation of Nitrogen, Argon, and Oxygen in Dissolved Air for Determination of Triple Oxygen Isotopes by Dual-Inlet Mass Spectrometry. Anal Chem 2003; 75:4913-7. [PMID: 14674471 DOI: 10.1021/ac034314r] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A chromatographic system was developed to separate oxygen from nitrogen, argon, carbon dioxide, and water vapor mixture for the determination of precise isotopic ratio measurements of oxygen in dissolved air. This system separates oxygen not only quantitatively but also rapidly as well; typical oxygen separation takes about 30 min. Fractionation of oxygen between liquid and gas phase was found to be similar to that of earlier reports.
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Affiliation(s)
- V V S S Sarma
- Hydrospheric-Atmospheric Research Center and Graduate School of Environmental Studies, Nagoya University, Furo-cho, Chikusa-ku, Nagoya-464 8601, Japan.
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23
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Lee ES, Birkham TK, Wassenaar LI, Hendry MJ. Microbial respiration and diffusive transport of O2, 16O2, and 18O15O in unsaturated soils and geologic sediments. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2003; 37:2913-2919. [PMID: 12875394 DOI: 10.1021/es026146a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Molecular oxygen (O2) in unsaturated geologic sediments plays an important role in soil respiration, biodegradation of organic contaminants, metal oxidation, and global oxygen and carbon cycling, yet little is known about oxygen isotope fractionation during the consumption and transport of O2 in unsaturated zones. We used a laboratory kinetic cell technique to quantify isotope fractionation due to respiration and a numerical model to quantify both consumptive and diffusive fractionation of O2 isotopes at a field site comprised of unsaturated lacustrine sandy materials. The combined use of laboratory-based kinetic cell experiments and field-based isotope transport modeling provided an effective tool to characterize microbial respiration in unsaturated media. Based on results from the closed-system kinetic cells, O2 consumption and isotope fractionation were attributed to the alternative cyanide-resistant respiration pathway. At the field site, the modeled depth profiles for O2 and delta18O matched the measured in situ data and confirmed that the consumption of O2 was via the alternative respiration pathway. If the cyanide-resistant respiration pathway is indeed widespread in soils, its high oxygen isotope enrichment factor could help to explain the discrepancy between the predicted present-day Dole effect (+20.8/1000) and the observed Dole effect (+23.5/1000). Thus, further soil O2 isotope studies are needed to better characterize and model the fractionation of oxygen isotopes during subsurface respiration and the potential impact on the isotopic content of atmospheric O2.
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Affiliation(s)
- Eung Seok Lee
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5E2
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24
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Barkan E, Luz B. High-precision measurements of 17O/16O and 18O/16O of O2 and O2/Ar ratio in air. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2003; 17:2809-2814. [PMID: 14673831 DOI: 10.1002/rcm.1267] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A method for high-precision and high-accuracy mass spectrometric measurements of the ratios among the three oxygen isotopes, and of the O(2)/Ar ratio, is presented. It involves separation of the O(2)-Ar mixture from air and includes a fully automated system that ensures highly reliable sample processing. Repeated measurements of atmospheric oxygen yield the repeatability (+/-SE x t, standard error of the mean (n = 12) multiplied by Student's t-factor for a 95% confidence limit) of 0.004, 0.003 and 0.2 per thousand for delta(18)O, delta(17)O and delta O(2)/Ar, respectively.
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Affiliation(s)
- Eugeni Barkan
- The Institute of Earth Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
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25
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Abe O, Yoshida N. Partial pressure dependency of 17O/16O and 18O/16O of molecular oxygen in the mass spectrometer. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2003; 17:395-400. [PMID: 12590387 DOI: 10.1002/rcm.923] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A method to determine both (17)O/(16)O and (18)O/(16)O ratios for molecular oxygen with high precision by direct introduction into the mass spectrometer without gas separation is presented. Because both (17)O/(16)O and (18)O/(16)O in mixed gases have good linear correlations with their mixing ratios, these isotopic compositions can be determined without a gas-separation procedure by calibration using prepared standard gases with variable mixed ratios and by monitoring the amounts of fragment ions. Analytical precision for delta(17)O and delta(18)O of 45 and 7 per meg, respectively, were obtained. The observed partial pressure dependency of isotopic composition may be caused by isotope fractionation during admission from the ionization chamber into the flight tube of the mass spectrometer.
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Affiliation(s)
- Osamu Abe
- Graduate School of Environmental Studies, Nagoya University, Japan. oabe@@ihas.nagoya-u.ac.jp
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