Combined effect of bicarbonate and water in photosynthetic oxygen evolution and carbon neutrality

• Published in: Acta geochimica Vol. 42; no. 1; pp. 77 - 88
• Main Author: Wu, Yanyou
• Format: Journal Article
• Language: English
• Published: Heidelberg Science Press 01.02.2023; Springer Nature B.V; State Key Laboratory of Environmental Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,550081 Guiyang,People's Republic of China
• Subjects: Adaptability; Bicarbonates; Biosphere; Body condition; Carbon dioxide; Carbon dioxide emissions; Carbon neutrality; Carbonic anhydrase; Chemical equilibrium; Earth and Environmental Science; Earth Sciences; Emissions; Evolution; Geochemistry; Hydration; Hydrogen; Hydrosphere; Lithosphere; Metabolism; Organic carbon; Organic matter; Original Article; Oxidation; Oxygen; Photolysis; Photosynthesis; Photosystem II; Water; Stoichiometric relationship; Bicarbonate effect; Carbonic anhydrase; Dole effect; Water photolysis; Carbon metabolism; Bicarbonate photolysis
• ISSN: 2096-0956; 2365-7499
• DOI: 10.1007/s11631-022-00580-9

Carbon neutrality is widely concerned and highly valued by many countries. Biosphere has always maintained the balance between oxidized organic substances and assimilated organic matter, resulting in net-zero carbon dioxide (CO 2 ) emissions and maintaining its own carbon neutrality. Nature has set a good example for human beings to coordinate oxygen (O 2 ) balance and CO 2 balance, and achieve carbon neutrality. How does photosynthetic oxygen evolution initiate carbon and water neutrality? My synthesis shows that photosystem II functions as carbonic anhydrase to catalyze the reaction of CO 2 hydration under physiological conditions, and CO 2 hydration coupled with chemical equilibrium, H + +HCO 3 − →1/2 O 2  + 2e − +2 H + +CO 2 , occurs in a photosystem II core-complex. Meanwhile, I focused on the revisiting of four classical heavy oxygen (O 18 ) labeling experiments and found that bicarbonate can promote photosynthetic oxygen evolution, and that photosynthetic oxygen evolution can alternately come from bicarbonate and water, not only water. Bicarbonate photolysis and water photolysis account for half of the photosynthetic oxygen evolution respectively, which can well explain the bicarbonate effect, Dole effect and plants’ environmental adaptability. Photosynthetic oxygen evolution initiated the journey of water metabolism and carbon metabolism in nature, which led to the coupling as 1:1 (mol/mol) stoichiometric relationship between the reduction of CO 2 and oxidation of organic carbon, coordinated the evolution of the atmosphere, hydrosphere, lithosphere and biosphere, and realized “carbon neutrality” in the whole Earth system.