The triple oxygen isotope signature \uffce\uff9417O in atmospheric CO2, also known as its \uffe2\uff80\uff9c17O excess,\uffe2\uff80\uff9d has been proposed as a tracer for gross primary production (the gross uptake of CO2 by vegetation through photosynthesis). We present the first global 3\uffe2\uff80\uff90D model simulations for \uffce\uff9417O in atmospheric CO2 together with a detailed model description and sensitivity analyses. In our 3\uffe2\uff80\uff90D model framework we include the stratospheric source of \uffce\uff9417O in CO2 and the surface sinks from vegetation, soils, ocean, biomass burning, and fossil fuel combustion. The effect of oxidation of atmospheric CO on \uffce\uff9417O in CO2 is also included in our model. We estimate that the global mean \uffce\uff9417O (defined as with \uffce\uffbbRL = 0.5229) of CO2 in the lowest 500\uffc2\uffa0m of the atmosphere is 39.6\uffc2\uffa0per meg, which is \uffe2\uff88\uffbc20\uffc2\uffa0per meg lower than estimates from existing box models. We compare our model results with a measured stratospheric \uffce\uff9417O in CO2 profile from Sodankyl\uffc3\uffa4 (Finland), which shows good agreement. In addition, we compare our model results with tropospheric measurements of \uffce\uff9417O in CO2 from G\uffc3\uffb6ttingen (Germany) and Taipei (Taiwan), which shows some agreement but we also find substantial discrepancies that are subsequently discussed. Finally, we show model results for Zotino (Russia), Mauna Loa (United States), Manaus (Brazil), and South Pole, which we propose as possible locations for future measurements of \uffce\uff9417O in tropospheric CO2 that can help to further increase our understanding of the global budget of \uffce\uff9417O in atmospheric CO2.
", "keywords": ["CARBONIC-ANHYDRASE ACTIVITY", "550", "STRATOSPHERIC CO2", "STOMATAL CONDUCTANCE", "TRACER", "stable isotopes", "MASS", "carbon dioxide (CO)", "01 natural sciences", "7. Clean energy", "DIOXIDE EXCHANGE", "O excess (\u0394O)", "3-DIMENSIONAL SYNTHESIS", "carbon dioxide (CO2)", "carbon cycle", "O-17 excess (Delta O-17)", "SDG 13 - Climate Action", "SDG 14 - Life Below Water", "Research Articles", "0105 earth and related environmental sciences", "O-18 CONTENT", "info:eu-repo/classification/ddc/550", "mass-independent fractionation (MIF)", "ddc:550", "gross primary production (GPP)", "15. Life on land", "Earth sciences", "13. Climate action", "MODEL TM5", "17O excess (\u039417O)", "FIRE EMISSIONS"]}, "links": [{"href": "https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2019JD030387"}, {"href": "https://doi.org/10.1029/2019jd030387"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Journal%20of%20Geophysical%20Research%3A%20Atmospheres", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1029/2019jd030387", "name": "item", "description": "10.1029/2019jd030387", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1029/2019jd030387"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2019-08-04T00:00:00Z"}}, {"id": "10.5194/bg-17-3903-2020", "type": "Feature", "geometry": null, "properties": {"updated": "2026-05-23T16:21:23Z", "type": "Journal Article", "created": "2020-07-31", "title": "Leaf-scale quantification of the effect of photosynthetic gas exchange on \u0394<sup>17</sup>O of atmospheric CO<sub>2</sub>", "description": "Abstract. Understanding the processes that affect the triple oxygen isotope composition of atmospheric CO2 during gas exchange can help constrain the interaction and fluxes between the atmosphere and the biosphere. We conducted leaf cuvette experiments under controlled conditions using three plant species. The experiments were conducted at two different light intensities and using CO2 with different \uffce\uff9417O. We directly quantify the effect of photosynthesis on \uffce\uff9417O of atmospheric CO2 for the first time. Our results demonstrate the established theory for \uffce\uffb418O is applicable to \uffce\uff9417O(CO2) at leaf level, and we confirm that the following two key factors determine the effect of photosynthetic gas exchange on the \uffce\uff9417O of atmospheric CO2. The relative difference between \uffce\uff9417O of the CO2 entering the leaf and the CO2 in equilibrium with leaf water and the back-diffusion flux of CO2 from the leaf to the atmosphere, which can be quantified by the cm\uffe2\uff88\uff95ca ratio, where ca is the CO2 mole fraction in the surrounding air and cm is the one at the site of oxygen isotope exchange between CO2 and H2O. At low cm\uffe2\uff88\uff95ca ratios the discrimination is governed mainly by diffusion into the leaf, and at high cm\uffe2\uff88\uff95ca ratios it is governed by back-diffusion of CO2 that has equilibrated with the leaf water. Plants with a higher cm\uffe2\uff88\uff95ca ratio modify the \uffce\uff9417O of atmospheric CO2 more strongly than plants with a lower cm\uffe2\uff88\uff95ca ratio. Based on the leaf cuvette experiments, the global value for discrimination against \uffce\uff9417O of atmospheric CO2 during photosynthetic gas exchange is estimated to be -0.57\uffc2\uffb10.14\uffe2\uff80\uff89\uffe2\uff80\uffb0 using cm\uffe2\uff88\uff95ca values of 0.3 and 0.7 for C4 and C3 plants, respectively. The main uncertainties in this global estimate arise from variation in cm\uffe2\uff88\uff95ca ratios among plants and growth conditions.
", "keywords": ["0106 biological sciences", "0301 basic medicine", "QE1-996.5", "CARBONIC-ANHYDRASE ACTIVITY", "Ecology", "OXYGEN-ISOTOPE FRACTIONATION", "MESOPHYLL CONDUCTANCE", "Geology", "15. Life on land", "01 natural sciences", "O-18/O-16 RATIOS", "MASS-INDEPENDENT FRACTIONATION", "03 medical and health sciences", "HIGH-PRECISION MEASUREMENTS", "Life", "13. Climate action", "3-DIMENSIONAL SYNTHESIS", "QH501-531", "STABLE-ISOTOPES", "Life Science", "14. Life underwater", "TRIPLE OXYGEN", "DIOXIDE", "QH540-549.5", "0105 earth and related environmental sciences"]}, "links": [{"href": "https://doi.org/10.5194/bg-17-3903-2020"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Biogeosciences", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.5194/bg-17-3903-2020", "name": "item", "description": "10.5194/bg-17-3903-2020", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.5194/bg-17-3903-2020"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2020-03-27T00:00:00Z"}}], "links": [{"rel": "self", "type": "application/geo+json", "title": "This document as GeoJSON", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=CARBONIC-ANHYDRASE+ACTIVITY&f=json", "hreflang": "en-US"}, {"rel": "alternate", "type": "text/html", "title": "This document as HTML", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=CARBONIC-ANHYDRASE+ACTIVITY&f=html", "hreflang": "en-US"}, {"rel": "collection", "type": "application/json", "title": "Collection URL", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main", "hreflang": "en-US"}, {"type": "application/geo+json", "rel": "first", "title": "items (first)", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=CARBONIC-ANHYDRASE+ACTIVITY&", "hreflang": "en-US"}, {"rel": "last", "type": "application/geo+json", "title": "items (last)", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=CARBONIC-ANHYDRASE+ACTIVITY&offset=2", "hreflang": "en-US"}], "numberMatched": 2, "numberReturned": 2, "distributedFeatures": [], "timeStamp": "2026-05-24T23:11:33.204122Z"}