PROFILPELAJAR.COM

The hydrogen cycle consists of hydrogen exchanges between biotic (living) and abiotic (non-living) sources and sinks of hydrogen-containing compounds.

Hydrogen (H) is the most abundant element in the universe.^[1] On Earth, common H-containing inorganic molecules include water (H₂O), hydrogen gas (H₂), hydrogen sulfide (H₂S), and ammonia (NH₃). Many organic compounds also contain H atoms, such as hydrocarbons and organic matter. Given the ubiquity of hydrogen atoms in inorganic and organic chemical compounds, the hydrogen cycle is focused on molecular hydrogen, H₂.

As a consequence of microbial metabolisms or naturally occurring rock-water interactions, hydrogen gas can be created. Other bacteria may then consume free H2, which may also be oxidised photochemically in the atmosphere or lost to space. Hydrogen is also thought to be an important reactant in pre-biotic chemistry and the early evolution of life on Earth, and potentially elsewhere in the Solar System.^[2]

Abiotic cycles

Sources

Abiotic sources of hydrogen gas include water-rock and photochemical reactions. Exothermic serpentinization reactions between water and olivine minerals produce H₂ in the marine or terrestrial subsurface.^[3]^[4] In the ocean, hydrothermal vents erupt magma and altered seawater fluids including abundant H₂, depending on the temperature regime and host rock composition.^[5]^[4] Molecular hydrogen can also be produced through photooxidation (via solar UV radiation) of some mineral species such as siderite in anoxic aqueous environments. This may have been an important process in the upper regions of early Earth's Archaean oceans.^[6]

Sinks

Because H₂ is the lightest element, atmospheric H₂ can readily be lost to space via Jeans escape, an irreversible process that drives Earth's net mass loss.^[7] Photolysis of heavier compounds not prone to escape, such as CH₄ or H₂O, can also liberate H₂ from the upper atmosphere and contribute to this process. Another major sink of free atmospheric H₂ is photochemical oxidation by hydroxyl radicals (•OH), which forms water.^{[citation needed]}

Anthropogenic sinks of H₂ include synthetic fuel production through the Fischer-Tropsch reaction and artificial nitrogen fixation through the Haber-Bosch process to produce nitrogen fertilizers.^{[citation needed]}

Biotic cycles

Many microbial metabolisms produce or consume H₂.

Production

Hydrogen is produced by hydrogenases and nitrogenases enzymes in many microorganisms, some of which are being studied for their potential for biofuel production.^[8]^[9] These H₂-metabolizing enzymes are found in all three domains of life, and out of known genomes over 30% of microbial taxa contain hydrogenase genes.^[10] Fermentation produces H₂ from organic matter as part of the anaerobic microbial food chain^[11] via light-dependent or light-independent pathways.^[8]

Consumption

Biological soil uptake is the dominant sink of atmospheric H₂.^[12] Both aerobic and anaerobic microbial metabolisms consume H₂ by oxidizing it in order to reduce other compounds during respiration. Aerobic H₂ oxidation is known as the Knallgas reaction.^[13]

Anaerobic H₂ oxidation often occurs during interspecies hydrogen transfer in which H₂ produced during fermentation is transferred to another organism, which uses the H₂ to reduce CO₂ to CH₄ or acetate, SO²⁻
₄ to H₂S, or Fe³⁺ to Fe²⁺. Interspecies hydrogen transfer keeps H₂ concentrations very low in most environments because fermentation becomes less thermodynamically favorable as the partial pressure of H₂ increases.^[11]

Relevance for the global climate

H₂ can interfere with the removal of methane from the atmosphere, a greenhouse gas. Typically, atmospheric CH₄ is oxidized by hydroxyl radicals (^•OH), but H₂ can also react with ^•OH to reduce it to H₂O.^[14]

CH₄ + ^•OH → ^•CH₃ + H₂O

H₂ + ^•OH → H^• + H₂O

Implications for astrobiology

Hydrothermal H₂ may have played a major role in pre-biotic chemistry.^[15] Production of H₂ by serpentinization supported formation of the reactants proposed in the iron-sulfur world origin of life hypothesis.^[16] The subsequent evolution of hydrogenotrophic methanogenesis is hypothesized as one of the earliest metabolisms on Earth.^[17]^[2]

Serpentinization can occur on any planetary body with chondritic composition. The discovery of H₂ on other ocean worlds, such as Enceladus,^[18]^[19]^[20] suggests that similar processes are ongoing elsewhere in the Solar System, and potentially in other planetary systems as well.^[13]

References

^ Cameron AG (1973). "Abundances of the elements in the solar system". Space Science Reviews. 15 (1): 121. Bibcode:1973SSRv...15..121C. doi:10.1007/BF00172440. ISSN 0038-6308. S2CID 120201972.
^ ^a ^b Colman DR, Poudel S, Stamps BW, Boyd ES, Spear JR (July 2017). "The deep, hot biosphere: Twenty-five years of retrospection". Proceedings of the National Academy of Sciences of the United States of America. 114 (27): 6895–6903. Bibcode:2017PNAS..114.6895C. doi:10.1073/pnas.1701266114. PMC 5502609. PMID 28674200.
^ Russell MJ, Hall AJ, Martin W (December 2010). "Serpentinization as a source of energy at the origin of life". Geobiology. 8 (5): 355–71. Bibcode:2010Gbio....8..355R. doi:10.1111/j.1472-4669.2010.00249.x. PMID 20572872.
^ ^a ^b Konn C, Charlou JL, Holm NG, Mousis O (May 2015). "The production of methane, hydrogen, and organic compounds in ultramafic-hosted hydrothermal vents of the Mid-Atlantic Ridge". Astrobiology. 15 (5): 381–99. Bibcode:2015AsBio..15..381K. doi:10.1089/ast.2014.1198. PMC 4442600. PMID 25984920.
^ Petersen JM, Zielinski FU, Pape T, Seifert R, Moraru C, Amann R, et al. (August 2011). "Hydrogen is an energy source for hydrothermal vent symbioses". Nature. 476 (7359): 176–80. Bibcode:2011Natur.476..176P. doi:10.1038/nature10325. PMID 21833083. S2CID 25578.
^ Kim JD, Yee N, Nanda V, Falkowski PG (June 2013). "Anoxic photochemical oxidation of siderite generates molecular hydrogen and iron oxides". Proceedings of the National Academy of Sciences of the United States of America. 110 (25): 10073–7. Bibcode:2013PNAS..11010073K. doi:10.1073/pnas.1308958110. PMC 3690895. PMID 23733945.
^ Catling DC, Zahnle KJ, McKay C (August 2001). "Biogenic methane, hydrogen escape, and the irreversible oxidation of early Earth". Science. 293 (5531): 839–43. Bibcode:2001Sci...293..839C. doi:10.1126/science.1061976. PMID 11486082. S2CID 37386726.
^ ^a ^b Khetkorn W, Rastogi RP, Incharoensakdi A, Lindblad P, Madamwar D, Pandey A, Larroche C (November 2017). "Microalgal hydrogen production - A review". Bioresource Technology. 243: 1194–1206. Bibcode:2017BiTec.243.1194K. doi:10.1016/j.biortech.2017.07.085. PMID 28774676.
^ Das D (2001). "Hydrogen production by biological processes: a survey of literature". International Journal of Hydrogen Energy. 26 (1): 13–28. Bibcode:2001IJHE...26...13D. doi:10.1016/S0360-3199(00)00058-6.
^ Peters JW, Schut GJ, Boyd ES, Mulder DW, Shepard EM, Broderick JB, King PW, Adams MW (June 2015). "[FeFe]- and [NiFe]-hydrogenase diversity, mechanism, and maturation" (PDF). Biochimica et Biophysica Acta (BBA) - Molecular Cell Research. 1853 (6): 1350–69. doi:10.1016/j.bbamcr.2014.11.021. PMID 25461840.
^ ^a ^b Kirchman DL (2011-02-02). Processes in Microbial Ecology. Oxford University Press. doi:10.1093/acprof:oso/9780199586936.001.0001. ISBN 9780199586936.
^ Rhee TS, Brenninkmeijer CA, Röckmann T (2006-05-19). "The overwhelming role of soils in the global atmospheric hydrogen cycle". Atmospheric Chemistry and Physics. 6 (6): 1611–1625. Bibcode:2006ACP.....6.1611R. doi:10.5194/acp-6-1611-2006.
^ ^a ^b Seager S, Schrenk M, Bains W (January 2012). "An astrophysical view of Earth-based metabolic biosignature gases". Astrobiology. 12 (1): 61–82. Bibcode:2012AsBio..12...61S. doi:10.1089/ast.2010.0489. hdl:1721.1/73073. PMID 22269061.
^ Novelli PC, Lang PM, Masarie KA, Hurst DF, Myers R, Elkins JW (1999-12-01). "Molecular hydrogen in the troposphere: Global distribution and budget". Journal of Geophysical Research: Atmospheres. 104 (D23): 30427–30444. Bibcode:1999JGR...10430427N. doi:10.1029/1999jd900788.
^ Colín-García M (2016). "Hydrothermal vents and prebiotic chemistry: a review". Boletín de la Sociedad Geológica Mexicana. 68 (3): 599–620. doi:10.18268/BSGM2016v68n3a13.
^ Wächtershäuser G. "Origin of life in an iron–sulfur world". The Molecular Origins of Life. Cambridge University Press. pp. 206–218. ISBN 9780511626180.
^ Boyd ES, Schut GJ, Adams MW, Peters JW (2014-09-01). "Hydrogen Metabolism and the Evolution of Biological Respiration". Microbe Magazine. 9 (9): 361–367. doi:10.1128/microbe.9.361.1.
^ Seewald JS (April 2017). "Detecting molecular hydrogen on Enceladus". Science. 356 (6334): 132–133. Bibcode:2017Sci...356..132S. doi:10.1126/science.aan0444. PMID 28408557. S2CID 206658660.
^ Hsu HW, Postberg F, Sekine Y, Shibuya T, Kempf S, Horányi M, et al. (March 2015). "Ongoing hydrothermal activities within Enceladus". Nature. 519 (7542): 207–10. Bibcode:2015Natur.519..207H. doi:10.1038/nature14262. PMID 25762281. S2CID 4466621.
^ Glein CR, Baross JA, Waite Jr JH (2015). "The pH of Enceladus' ocean". Geochimica et Cosmochimica Acta. 162: 202–219. arXiv:1502.01946. Bibcode:2015GeCoA.162..202G. doi:10.1016/j.gca.2015.04.017. S2CID 119262254.

[1] Cameron AG (1973). "Abundances of the elements in the solar system". Space Science Reviews. 15 (1): 121. Bibcode:1973SSRv...15..121C. doi:10.1007/BF00172440. ISSN 0038-6308. S2CID 120201972.

[Colman_2017-2] Colman DR, Poudel S, Stamps BW, Boyd ES, Spear JR (July 2017). "The deep, hot biosphere: Twenty-five years of retrospection". Proceedings of the National Academy of Sciences of the United States of America. 114 (27): 6895–6903. Bibcode:2017PNAS..114.6895C. doi:10.1073/pnas.1701266114. PMC 5502609. PMID 28674200.

[:0-3] Russell MJ, Hall AJ, Martin W (December 2010). "Serpentinization as a source of energy at the origin of life". Geobiology. 8 (5): 355–71. Bibcode:2010Gbio....8..355R. doi:10.1111/j.1472-4669.2010.00249.x. PMID 20572872.

[Konn_2015-4] Konn C, Charlou JL, Holm NG, Mousis O (May 2015). "The production of methane, hydrogen, and organic compounds in ultramafic-hosted hydrothermal vents of the Mid-Atlantic Ridge". Astrobiology. 15 (5): 381–99. Bibcode:2015AsBio..15..381K. doi:10.1089/ast.2014.1198. PMC 4442600. PMID 25984920.

[5] Petersen JM, Zielinski FU, Pape T, Seifert R, Moraru C, Amann R, et al. (August 2011). "Hydrogen is an energy source for hydrothermal vent symbioses". Nature. 476 (7359): 176–80. Bibcode:2011Natur.476..176P. doi:10.1038/nature10325. PMID 21833083. S2CID 25578.

[6] Kim JD, Yee N, Nanda V, Falkowski PG (June 2013). "Anoxic photochemical oxidation of siderite generates molecular hydrogen and iron oxides". Proceedings of the National Academy of Sciences of the United States of America. 110 (25): 10073–7. Bibcode:2013PNAS..11010073K. doi:10.1073/pnas.1308958110. PMC 3690895. PMID 23733945.

[7] Catling DC, Zahnle KJ, McKay C (August 2001). "Biogenic methane, hydrogen escape, and the irreversible oxidation of early Earth". Science. 293 (5531): 839–43. Bibcode:2001Sci...293..839C. doi:10.1126/science.1061976. PMID 11486082. S2CID 37386726.

[Khetkorn_2017-8] Khetkorn W, Rastogi RP, Incharoensakdi A, Lindblad P, Madamwar D, Pandey A, Larroche C (November 2017). "Microalgal hydrogen production - A review". Bioresource Technology. 243: 1194–1206. Bibcode:2017BiTec.243.1194K. doi:10.1016/j.biortech.2017.07.085. PMID 28774676.

[9] Das D (2001). "Hydrogen production by biological processes: a survey of literature". International Journal of Hydrogen Energy. 26 (1): 13–28. Bibcode:2001IJHE...26...13D. doi:10.1016/S0360-3199(00)00058-6.

[10] Peters JW, Schut GJ, Boyd ES, Mulder DW, Shepard EM, Broderick JB, King PW, Adams MW (June 2015). "[FeFe]- and [NiFe]-hydrogenase diversity, mechanism, and maturation" (PDF). Biochimica et Biophysica Acta (BBA) - Molecular Cell Research. 1853 (6): 1350–69. doi:10.1016/j.bbamcr.2014.11.021. PMID 25461840.

[Kirchman_2011-11] Kirchman DL (2011-02-02). Processes in Microbial Ecology. Oxford University Press. doi:10.1093/acprof:oso/9780199586936.001.0001. ISBN 9780199586936.

[12] Rhee TS, Brenninkmeijer CA, Röckmann T (2006-05-19). "The overwhelming role of soils in the global atmospheric hydrogen cycle". Atmospheric Chemistry and Physics. 6 (6): 1611–1625. Bibcode:2006ACP.....6.1611R. doi:10.5194/acp-6-1611-2006.

[Seager_2012-13] Seager S, Schrenk M, Bains W (January 2012). "An astrophysical view of Earth-based metabolic biosignature gases". Astrobiology. 12 (1): 61–82. Bibcode:2012AsBio..12...61S. doi:10.1089/ast.2010.0489. hdl:1721.1/73073. PMID 22269061.

[14] Novelli PC, Lang PM, Masarie KA, Hurst DF, Myers R, Elkins JW (1999-12-01). "Molecular hydrogen in the troposphere: Global distribution and budget". Journal of Geophysical Research: Atmospheres. 104 (D23): 30427–30444. Bibcode:1999JGR...10430427N. doi:10.1029/1999jd900788.

[15] Colín-García M (2016). "Hydrothermal vents and prebiotic chemistry: a review". Boletín de la Sociedad Geológica Mexicana. 68 (3): 599–620. doi:10.18268/BSGM2016v68n3a13.

[16] Wächtershäuser G. "Origin of life in an iron–sulfur world". The Molecular Origins of Life. Cambridge University Press. pp. 206–218. ISBN 9780511626180.

[17] Boyd ES, Schut GJ, Adams MW, Peters JW (2014-09-01). "Hydrogen Metabolism and the Evolution of Biological Respiration". Microbe Magazine. 9 (9): 361–367. doi:10.1128/microbe.9.361.1.

[18] Seewald JS (April 2017). "Detecting molecular hydrogen on Enceladus". Science. 356 (6334): 132–133. Bibcode:2017Sci...356..132S. doi:10.1126/science.aan0444. PMID 28408557. S2CID 206658660.

[19] Hsu HW, Postberg F, Sekine Y, Shibuya T, Kempf S, Horányi M, et al. (March 2015). "Ongoing hydrothermal activities within Enceladus". Nature. 519 (7542): 207–10. Bibcode:2015Natur.519..207H. doi:10.1038/nature14262. PMID 25762281. S2CID 4466621.

[20] Glein CR, Baross JA, Waite Jr JH (2015). "The pH of Enceladus' ocean". Geochimica et Cosmochimica Acta. 162: 202–219. arXiv:1502.01946. Bibcode:2015GeCoA.162..202G. doi:10.1016/j.gca.2015.04.017. S2CID 119262254.

[1]

[2]

[3]

[4]

[5]

[6]

[7]

[8]

[9]

[10]

[11]

[12]

[13]

[14]

[15]

[16]

[17]

[18]

[19]

[20]

PROFILPELAJAR.COM

Hydrogen cycle

Abiotic cycles

Sources

Sinks

Biotic cycles

Production

Consumption

Relevance for the global climate

Implications for astrobiology

See also

References

Read other articles:

Bronisław Malinowski

Caring and Killing

Associazione Sportiva Acquapozzillo 1971-1972

Peter Skaarup

Синелобый амазон

Dasht-e Lut

Salopette

Muppet Babies (2018 TV series)

USS Finback (SS-230)

Aplastodiscus perviridis

Hot 'n Now

علاقات كوبا الخارجية

سياحة مستدامة

Oussama Kassir

Alicia en el país de las maravillas (película de 1951)

1971 Copa Libertadores

Eros (conceito)

Allemagne aux Jeux olympiques

Ship Characteristics Board

Trinh tiết