An elucidatory model of oxygen's partial pressure inside substomatal cavities
<p>A parsimonious model based on Dalton's law reveals substomatal cavities to be dilute in oxygen (O<span class="inline-formula"><sub>2</sub>)</span>, despite photosynthetic O<span class="inline-formula"><sub>2</sub></span&g...
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Copernicus Publications
2025-02-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/22/785/2025/bg-22-785-2025.pdf |
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| author | A. S. Kowalski A. S. Kowalski |
| author_facet | A. S. Kowalski A. S. Kowalski |
| author_sort | A. S. Kowalski |
| collection | DOAJ |
| description | <p>A parsimonious model based on Dalton's law reveals substomatal cavities to be dilute in oxygen (O<span class="inline-formula"><sub>2</sub>)</span>, despite photosynthetic O<span class="inline-formula"><sub>2</sub></span> production. Transpiration elevates the partial pressure of water vapour but counteractively depresses the partial pressures of dry air's components – proportionally including O<span class="inline-formula"><sub>2</sub></span> – preserving cavity pressurization that is negligible as regards air composition. Suppression of O<span class="inline-formula"><sub>2</sub></span> by humidification overwhelms photosynthetic enrichment, reducing the O<span class="inline-formula"><sub>2</sub></span> molar fraction inside cool or warm leaves by hundreds or thousands of parts per million. This elucidates the mechanisms that realize O<span class="inline-formula"><sub>2</sub></span> transport: diffusion cannot account for up-gradient conveyance of O<span class="inline-formula"><sub>2</sub></span> from dilute cavities through stomata to the more aerobic atmosphere. Rather, leaf O<span class="inline-formula"><sub>2</sub></span> emissions depend on non-diffusive transport via mass flow forced by cavity pressurization, which is not negligible in the context of dynamics. Non-diffusive O<span class="inline-formula"><sub>2</sub></span> expulsion overcomes massive inward O<span class="inline-formula"><sub>2</sub></span> diffusion to force net O<span class="inline-formula"><sub>2</sub></span> emission. At very high leaf temperatures, mass flow also influences transport of water vapour and carbon dioxide, physically decoupling their exchanges and reducing water-use efficiency, independently of stomatal regulation.</p> |
| format | Article |
| id | doaj-art-b95531b185a24c39ae7e91d6284d518e |
| institution | Kabale University |
| issn | 1726-4170 1726-4189 |
| language | English |
| publishDate | 2025-02-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj-art-b95531b185a24c39ae7e91d6284d518e2025-02-12T07:41:26ZengCopernicus PublicationsBiogeosciences1726-41701726-41892025-02-012278578910.5194/bg-22-785-2025An elucidatory model of oxygen's partial pressure inside substomatal cavitiesA. S. Kowalski0A. S. Kowalski1Department of Applied Physics, University of Granada, Granada, 18071, SpainAndalusian Institute for Earth System Research (IISTA), Granada, 18071, Spain<p>A parsimonious model based on Dalton's law reveals substomatal cavities to be dilute in oxygen (O<span class="inline-formula"><sub>2</sub>)</span>, despite photosynthetic O<span class="inline-formula"><sub>2</sub></span> production. Transpiration elevates the partial pressure of water vapour but counteractively depresses the partial pressures of dry air's components – proportionally including O<span class="inline-formula"><sub>2</sub></span> – preserving cavity pressurization that is negligible as regards air composition. Suppression of O<span class="inline-formula"><sub>2</sub></span> by humidification overwhelms photosynthetic enrichment, reducing the O<span class="inline-formula"><sub>2</sub></span> molar fraction inside cool or warm leaves by hundreds or thousands of parts per million. This elucidates the mechanisms that realize O<span class="inline-formula"><sub>2</sub></span> transport: diffusion cannot account for up-gradient conveyance of O<span class="inline-formula"><sub>2</sub></span> from dilute cavities through stomata to the more aerobic atmosphere. Rather, leaf O<span class="inline-formula"><sub>2</sub></span> emissions depend on non-diffusive transport via mass flow forced by cavity pressurization, which is not negligible in the context of dynamics. Non-diffusive O<span class="inline-formula"><sub>2</sub></span> expulsion overcomes massive inward O<span class="inline-formula"><sub>2</sub></span> diffusion to force net O<span class="inline-formula"><sub>2</sub></span> emission. At very high leaf temperatures, mass flow also influences transport of water vapour and carbon dioxide, physically decoupling their exchanges and reducing water-use efficiency, independently of stomatal regulation.</p>https://bg.copernicus.org/articles/22/785/2025/bg-22-785-2025.pdf |
| spellingShingle | A. S. Kowalski A. S. Kowalski An elucidatory model of oxygen's partial pressure inside substomatal cavities Biogeosciences |
| title | An elucidatory model of oxygen's partial pressure inside substomatal cavities |
| title_full | An elucidatory model of oxygen's partial pressure inside substomatal cavities |
| title_fullStr | An elucidatory model of oxygen's partial pressure inside substomatal cavities |
| title_full_unstemmed | An elucidatory model of oxygen's partial pressure inside substomatal cavities |
| title_short | An elucidatory model of oxygen's partial pressure inside substomatal cavities |
| title_sort | elucidatory model of oxygen s partial pressure inside substomatal cavities |
| url | https://bg.copernicus.org/articles/22/785/2025/bg-22-785-2025.pdf |
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