Oxygen isotope fractionation between CO2 and H2O

Brenninkmeijer, C. A. M.; Kraft, Philipp; Mook, W.G.

doi:10.1016/s0009-2541(83)80015-1

Cited by 131 publications

(164 citation statements)

References 14 publications

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“…3. Values of δ eq were converted into a soil water isotope composition equivalent (δ sw-eq , in ‰ VSMOW) according to Brenninkmeijer et al (1983): δ sw-eq = δ eq + 0.20 (T s − 297.15). According to Wingate et al (2009) this δ sw-eq should correspond to the soil water δ 18 O at a depth z eq (m) given by…”

Section: Co 2 Mixing Ratio and Stable Isotope Measurementsmentioning

confidence: 99%

The role of soil pH on soil carbonic anhydrase activity

et al. 2018

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Abstract. Carbonic anhydrases (CAs) are metalloenzymes present in plants and microorganisms that catalyse the interconversion of CO 2 and water to bicarbonate and protons. Because oxygen isotopes are also exchanged during this reaction, the presence of CA also modifies the contribution of soil and plant CO 18 O fluxes to the global budget of atmospheric CO 18 O. The oxygen isotope signatures (δ 18 O) of these fluxes differ as leaf water pools are usually more enriched than soil water pools, and this difference is used to partition the net CO 2 flux over land into soil respiration and plant photosynthesis. Nonetheless, the use of atmospheric CO 18 O as a tracer of land surface CO 2 fluxes requires a good knowledge of soil CA activity. Previous studies have shown that significant differences in soil CA activity are found in different biomes and seasons, but our understanding of the environmental and ecological drivers responsible for the spatial and temporal patterns observed in soil CA activity is still limited. One factor that has been overlooked so far is pH. Soil pH is known to strongly influence microbial community composition, richness and diversity in addition to governing the speciation of CO 2 between the different carbonate forms. In this study we investigated the CO 2 -H 2 O isotopic exchange rate (k iso ) in six soils with pH varying from 4.5 to 8.5. We also artificially increased the soil CA concentration to test how pH and other soil properties (texture and phosphate content) affected the relationship between k iso and CA concentration. We found that soil pH was the primary driver of k iso after CA addition and that the chemical composition (i.e. phosphate content) played only a secondary role. We also found an offset between the δ 18 O of the water pool with which CO 2 equilibrates and total soil water (i.e. water extracted by vacuum distillation) that varied with soil texture. The reasons for this offset are still unknown.

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Section: Co 2 Mixing Ratio and Stable Isotope Measurementsmentioning

confidence: 99%

The role of soil pH on soil carbonic anhydrase activity

et al. 2018

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“…The isotope change depends directly on the δ 18 O(H 2 O) value while the fractionation constant possesses a strong temperature dependence (Brenninkmeijer et al, 1983). The variations in δ 18 O(CO 2 ) cannot be detected by the Keeling plot technique, which is based on the assumption that concentration changes are accompanied by isotope fractionation by sources or sinks.…”

Section: Variability In Tropospheric δ 18 O(co 2 )mentioning

confidence: 99%

Analysis of 13C and 18O isotope data of CO2 in CARIBIC aircraft samples as tracers of upper troposphere/lower stratosphere mixing and the global carbon cycle

et al. 2010

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Abstract. The project CARIBIC (http://caribic-atmospheric. com) aims to study atmospheric chemistry and transport by regularly measuring many compounds in the free troposphere and the upper troposphere/lowermost stratosphere (UT/LMS) by using passenger aircraft. Here we present CO 2 concentrations and isotope results, and analyze the data together with supporting trace gas data. 509 CARIBIC-2 samples (highest precision and accuracy δ 13 C(CO 2 ) and δ 18 O(CO 2 ) data) from June 2007 until March 2009, together with CARIBIC-1 samples (flights between November 1999 and April 2002, 350 samples in total, 270 for NH, mostly δ 13 C(CO 2 ) data) give a fairly extensive, unique data set for the NH free troposphere and the UT/LMS region. Total uncertainty of the data is the same as reported for the global monitoring program by NOAA-ESRL. To compare data from different years a de-trending is applied. In the UT/LMS region δ 13 C(CO 2 ), δ 18 O(CO 2 ) and CO 2 are found to correlate well with stratospheric tracers, in particular N 2 O; δ 18 O(CO 2 ) appears to be a useful, hitherto unused, tracer of atmospheric transport in the UT/LMS region and also inter-hemispheric mixing. By filtering out the LMS data (based on N 2 O distributions), the isotope variations for the free and upper troposphere are obtained. These variations have only small latitudinal gradients, if any, and are in good agreement with the Correspondence to: S. S. Assonov (assonov sergey@yahoo.com) data of selected NOAA stations in NH tropics. Correlations between δ 13 C(CO 2 ) and CO 2 are observed both within single flight(s) covering long distances and during certain seasons. The overall variability in de-trended δ 13 C(CO 2 ) and CO 2 for CARIBIC-1 and CARIBIC-2 are similar and are generally in agreement, which underscores agreement between high and low resolution sampling. Based on all correlations, we infer that the CO 2 distribution in the NH troposphere along CARIBIC flight routes is chiefly regulated by uplift and polewards transport of tropical air up to approximately 50 • N. The main reason for variability of signals in the troposphere (which is larger for the higher resolution sampling during CARIBIC-2) is mixing of different tropospheric air masses affected by different CO 2 sources and sinks. The effect of stratospheric flux appears to be limited. All in all it is demonstrated that CARIBIC produced new important and reliable data sets for little explored regions of the atmosphere. A logical next step will be global scale modeling of 13 C and especially 18 O, which is linked to the hydrological cycle.

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“…The carbon isotope composition of dissolved bicarbonates (δ 13 C diss-bicarb ) and the oxygen isotope composition of porewater (δ 18 O water ) in isotopic equilibrium with outgassed CO 2 at 20°C (storage temperature, see above) can be calculated using appropriate fractionation equations. This was done using fractionation factors of Mook et al (1974) for HCO 3 -CO 2 and of Brenninkmeijer at al. (1983) for CO 2 (g)-H 2 O(l).…”

Section: Origin Of Co 2 and Implication For Isotopic Characterizationmentioning

confidence: 99%

Stable isotope composition of CO2 outgassed from cores of argillites: a simple method to constrain δ18O of porewater and δ13C of dissolved carbon in mudrocks

Girard¹,

Fléhoc²,

Gaucher³

2005

Applied Geochemistry

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Oxygen isotope fractionation between CO2 and H2O

Cited by 131 publications

References 14 publications

The role of soil pH on soil carbonic anhydrase activity

The role of soil pH on soil carbonic anhydrase activity

Analysis of <sup>13</sup>C and <sup>18</sup>O isotope data of CO<sub>2</sub> in CARIBIC aircraft samples as tracers of upper troposphere/lower stratosphere mixing and the global carbon cycle

Stable isotope composition of CO2 outgassed from cores of argillites: a simple method to constrain δ18O of porewater and δ13C of dissolved carbon in mudrocks

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Oxygen isotope fractionation between CO2 and H2O

Cited by 131 publications

References 14 publications

The role of soil pH on soil carbonic anhydrase activity

The role of soil pH on soil carbonic anhydrase activity

Analysis of &lt;sup&gt;13&lt;/sup&gt;C and &lt;sup&gt;18&lt;/sup&gt;O isotope data of CO&lt;sub&gt;2&lt;/sub&gt; in CARIBIC aircraft samples as tracers of upper troposphere/lower stratosphere mixing and the global carbon cycle

Stable isotope composition of CO2 outgassed from cores of argillites: a simple method to constrain δ18O of porewater and δ13C of dissolved carbon in mudrocks

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Analysis of <sup>13</sup>C and <sup>18</sup>O isotope data of CO<sub>2</sub> in CARIBIC aircraft samples as tracers of upper troposphere/lower stratosphere mixing and the global carbon cycle