Isotopic signatures of production and uptake of H&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; by soil

Chen, Qianjie; Popa, M. E.; Batenburg, A. M.; Röckmann, Thomas

doi:10.5194/acp-15-13003-2015

Cited by 16 publications

(11 citation statements)

References 59 publications

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“…To our knowledge this is the first time that oceanic production of H 2 has been directly attributed to biological processes by using isotope techniques. For the samples collected from warm surface waters, our results verify the general assumption of a biological production process as a main source of oceanic H 2 to the atmosphere rather than photochemical or other sources (Herr et al, 1981;Conrad, 1988;Punshon and Moore, 2008;Moore et al, 2009). The dominance of biological formation at higher temperatures is qualitatively consistent with the general understanding of the temperature dependence of N 2 fixation rates for N 2 fixers such as e.g., Trichodesmium sp., which exhibit highest N 2 fixation rates within a temperature range between 24 to 30 • C (Breitbarth et al, 2007;Stal, 2009).…”

Section: Isotopic Composition Of Hsupporting

confidence: 85%

“…However, this clear attribution is only valid in water masses with higher temperatures and the unexpectedly high δD values in cooler waters indicate the influence of other processes. The isotopic enrichment that is expected for removal of H 2 (Chen et al, 2015;Rahn et al, 2003;Constant et al, 2016) is highly unlikely to cause a shift of almost 400 ‰ in δD from an assumed pure biological source, because in this case the removed fraction would have to be unrealistically large, as also recently argued for soil emitted H 2 (Chen et al, 2015). We suggest that a source of H 2 must exist in these surface waters, which produces H 2 that is out of isotope equilibrium with the water.…”

Section: Isotopic Composition Of Hmentioning

confidence: 99%

“…Oceanic H 2 production is assumed to be mainly biological, as a by-product of nitrogen (N 2 ) fixation (e.g., Conrad, 1988;Conrad and Seiler, 1988;Moore et al, 2009Moore et al, , 2014. H 2 is produced during N 2 fixation in equimolar proportions, but also reused as an energy source.…”

Section: Introductionmentioning

confidence: 99%

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Isotopic evidence for biogenic molecular hydrogen production in the Atlantic Ocean

et al. 2016

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Abstract. Oceans are a net source of molecular hydrogen (H2) to the atmosphere. The production of marine H2 is assumed to be mainly biological by N2 fixation, but photochemical pathways are also discussed. We present measurements of mole fraction and isotopic composition of dissolved and atmospheric H2 from the southern and northern Atlantic between 2008 and 2010. In total almost 400 samples were taken during 5 cruises along a transect between Punta Arenas (Chile) and Bremerhaven (Germany), as well as at the coast of Mauritania.The isotopic source signatures of dissolved H2 extracted from surface water are highly deuterium-depleted and correlate negatively with temperature, showing δD values of (−629 ± 54) ‰ for water temperatures at (27 ± 3) °C and (−249 ± 88) ‰ below (19 ± 1) °C. The results for warmer water masses are consistent with the biological production of H2. This is the first time that marine H2 excess has been directly attributed to biological production by isotope measurements. However, the isotope values obtained in the colder water masses indicate that beside possible biological production, a significant different source should be considered.The atmospheric measurements show distinct differences between both hemispheres as well as between seasons. Results from the global chemistry transport model TM5 reproduce the measured H2 mole fractions and isotopic composition well. The climatological global oceanic emissions from the GEMS database are in line with our data and previously published flux calculations. The good agreement between measurements and model results demonstrates that both the magnitude and the isotopic signature of the main components of the marine H2 cycle are in general adequately represented in current atmospheric models despite a proposed source different from biological production or a substantial underestimation of nitrogen fixation by several authors.

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Section: Isotopic Composition Of Hsupporting

confidence: 85%

Section: Isotopic Composition Of Hmentioning

confidence: 99%

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Isotopic evidence for biogenic molecular hydrogen production in the Atlantic Ocean

et al. 2016

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“…Recently, it became possible to analyze the D content of H 2 (δD) in small atmospheric samples at natural isotopic abundances . These measurements enabled the study of different components of the H 2 cycle and helped constrain the atmospheric H 2 budget, which as a consequence is currently relatively well understood on the large scale . Although H 2 isotope measurements have proven useful, they are difficult to perform, and only few labs had or have this capability.…”

Section: Background and Introductionmentioning

confidence: 99%

H₂ clumped isotope measurements at natural isotopic abundances

Popa

Paul

Janssen

et al. 2019

Rapid Comm Mass Spectrometry

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Rationale Molecular hydrogen (H 2 ) is an important gas for atmospheric chemistry, and an indirect greenhouse gas due to its reaction with OH. The isotopic composition of H 2 (δD) has been used to investigate its atmospheric budget; here we add a new observable, the clumped isotopic signature ΔDD, to the tools that can be used to study the global cycle of H 2 . Methods A method for determining ΔDD in H 2 was developed using the high‐resolution MAT 253‐Ultra isotope ratio mass spectrometer (Thermo Fisher). The HH, HD and DD abundances are quantified at medium resolution (M/ΔM ≈ 6000), which is sufficient for HD + and DD + to be distinguished from H 3 + and H 2 D + , respectively. The method involves sequential measurement of isotopologues, and DD is measured using an ion counter. For verification, catalytic ΔDD equilibration experiments were performed at temperatures of up to 850°C. Results The typical precision obtained for ΔDD is 2–6‰, close to the theoretical counting statistics limit, and adequate for detecting the expected natural variations. Compatibility and medium‐term reproducibility are consistent with the precision values. The method was validated using temperature equilibration experiments, which showed a dependence of ΔDD on temperature as expected form theoretical calculations. Conclusions We have established a method for determining ΔDD in H 2 at natural isotopic abundances, with a precision that is adequate for observing the expected variations in atmospheric and other natural H 2 . This method opens the road to new research on the natural H 2 cycle.

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“…Glass flasks or bulbs of 0.5 -1 L volume sealed with hoses or O-rings have been found to provide stable, long-term storage of a variety of atmospheric trace gases and their stable isotope ratios (Rothe et al, 2005;Thrun et al, 1979), and are routinely used for sampling campaigns involving isotopic ratios of H 2 (Chen et al, 2015;Schmitt et al, 2009). Other similar designs include stainless steel flasks and cylinders Sulyok et al, 2001).…”

mentioning

confidence: 99%

Technical Note: Inexpensive modification of Exetainers for the reliable storage of trace-level hydrogen and carbon monoxide gas samples

Nauer¹,

Chiri²,

Jirapanjawat³

et al. 2020

Preprint

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Abstract. Atmospheric trace gases such as dihydrogen (H2), carbon monoxide (CO) and methane (CH4) play important roles in microbial metabolism and biogeochemical cycles. Analysis of these gases at trace levels requires reliable storage of discrete samples of low volume. While commercial sampling vials such as Exetainers® have been tested for CH4 and other greenhouse gases, no information on reliable storage is available for H2 and CO. We show that vials sealed with butyl rubber stoppers are not suitable for storing H2 and CO due to release of these gases from rubber material. Treating butyl septa with NaOH reduced trace gas release, but contamination was still substantial, with H2 and CO concentrations in air samples increasing by a factor of 3 and 10 after 30 days of storage in conventional 12 mL Exetainers. Among the rubber materials tested, silicone showed the lowest potential for H2 and CO release. We thus propose to modify Exetainers by closing them with a silicone plug, and sealing them with a stainless steel bolt and O-ring for long-term storage. Such modified Exetainers exhibited stable concentrations of H2 and CH4 exceeding 60 days of storage at atmospheric and elevated (10 ppm) concentrations. The increase of CO was still measurable, but nine times lower than in conventional Exetainers with treated septa, and can be corrected for due to its linearity by storing a standard gas alongside the samples. The proposed modification is inexpensive, scalable and robust, and thus enables reliable storage of large numbers of low-volume gas samples from remote field locations.

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Isotopic signatures of production and uptake of H<sub>2</sub> by soil

Cited by 16 publications

References 59 publications

Isotopic evidence for biogenic molecular hydrogen production in the Atlantic Ocean

Isotopic evidence for biogenic molecular hydrogen production in the Atlantic Ocean

H₂ clumped isotope measurements at natural isotopic abundances

Technical Note: Inexpensive modification of Exetainers for the reliable storage of trace-level hydrogen and carbon monoxide gas samples

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Isotopic signatures of production and uptake of H&lt;sub&gt;2&lt;/sub&gt; by soil

Cited by 16 publications

References 59 publications

Isotopic evidence for biogenic molecular hydrogen production in the Atlantic Ocean

Isotopic evidence for biogenic molecular hydrogen production in the Atlantic Ocean

H2 clumped isotope measurements at natural isotopic abundances

Technical Note: Inexpensive modification of Exetainers for the reliable storage of trace-level hydrogen and carbon monoxide gas samples

Contact Info

Product

Resources

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Isotopic signatures of production and uptake of H<sub>2</sub> by soil

H₂ clumped isotope measurements at natural isotopic abundances