{"623090":{"#nid":"623090","#data":{"type":"news","title":"What Delayed Earth\u2019s Oxygenation?","body":[{"value":"\u003Cp\u003EPowering a massive biosphere on Earth, photosynthesis is the light-mediated reaction that converts carbon dioxide and water to carbohydrates and oxygen. About 2.3 billion years ago, this reaction led to a dramatic oxygenation of Earth\u0026rsquo;s atmosphere.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EEvidence exists for oxygen-releasing photosynthesis evolving much earlier \u0026ndash; perhaps as early as 3 billion years ago. However, the oxygen-rich atmosphere we take for granted today has existed for only about 10% of Earth\u0026rsquo;s 4.5-billion-year history. Why did oxygenation of the atmosphere occur so much later than the evolution of oxygen-releasing photosynthesis?\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026ldquo;The striking lag has remained an enduring puzzle in the fields of Earth history and planetary science,\u0026rdquo; says Christopher Reinhard, an assistant professor in the School of Earth and Atmospheric Sciences (EAS).\u003C\/p\u003E\r\n\r\n\u003Cp\u003EReinhard, former EAS postdoctoral researcher Kazumi Ozaki, and collaborators have proposed a solution to the puzzle. Their findings, \u003Ca href=\u0022https:\/\/www.nature.com\/articles\/s41467-019-10872-z.epdf?author_access_token=Xe8fIoWSeLjd5mHHB1LqR9RgN0jAjWel9jnR3ZoTv0OLYNktx_0XcbQycqbQWoo90jsyrzgyojnDSpqSnMyUUt1lJAsax_OCbLAQTySL8xwdP6pavs6K7bnluMB1nBMdpZSWmaeogDv0OMHE5lN_sA%3D%3D\u0022\u003Epublished in \u003Cem\u003ENature Communications\u003C\/em\u003E\u003C\/a\u003E, suggest that in the oceans of early Earth, oxygen-releasing photosynthesizers could not compete effectively with their primitive counterparts.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EModern photosynthesizers consume water and release oxygen. Primitive ones instead consume dissolved iron ions \u0026ndash; which would have been abundant in the oceans of early Earth. They produce rust as a byproduct instead of oxygen.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EUsing experimental microbiology, genomics, and large-scale biogeochemical modeling, \u0026ldquo;we found that photosynthetic bacteria that use iron instead of water are fierce competitors for light and nutrients,\u0026rdquo; says Ozaki, the paper\u0026rsquo;s first author and now an assistant professor in the Department of Environmental Science at Toho University, in Japan. \u0026ldquo;We propose that their ability to outcompete oxygen-producing photosynthesizers is an important component of Earth\u0026rsquo;s global oxygen cycle.\u0026rdquo;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EThe study is part of Reinhard\u0026rsquo;s research goal to understand how the evolution of the photosynthetic biosphere controlled the composition of Earth\u0026rsquo;s atmosphere. \u0026ldquo;We want to understand the timing of major biological innovations and their impact on the chemistry of Earth\u0026rsquo;s oceans and atmosphere. We consider these principles to be central in understanding our own evolutionary origins and the search for life beyond our solar system.\u0026rdquo;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026ldquo;Our results contribute to a deeper knowledge of the biological factors controlling the long-term evolution of Earth\u0026rsquo;s atmosphere,\u0026rdquo; Ozaki says. \u0026ldquo;They offer a better mechanistic understanding of the factors that promote oxygenation of the atmospheres of Earth-like planets beyond our solar system.\u0026rdquo; The results \u0026ldquo;yield an entirely new vantage from which to build theoretical models of Earth\u0026rsquo;s biogeochemical oxygen cycle,\u0026rdquo; Reinhard adds.\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EOther authors of the study are Katharine Thompson, Rachel Simister, and Sean Crowe of the University of British Columbia.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EReinhard acknowledges support from the NASA Astrobiology Institute, the NASA Postdoctoral Program, the Alfred P. Sloan Foundation, and the NASA Nexus for Exoplanet System Science (NExSS).\u003C\/p\u003E\r\n","summary":null,"format":"limited_html"}],"field_subtitle":[{"value":"Photosynthesizers using water, which releases oxygen, could not compete with those using iron"}],"field_summary":[{"value":"\u003Cp\u003EEvidence exists for oxygen-releasing photosynthesis evolving as early as 3 billion years ago. However, the oxygen-rich atmosphere we take for granted today has existed for only about 10% of Earth\u0026rsquo;s 4.5-billion-year history. Why did oxygenation of the atmosphere occur so much later than the evolution of oxygen-releasing photosynthesis?\u003C\/p\u003E\r\n","format":"limited_html"}],"field_summary_sentence":[{"value":"Photosynthesizers using water, which releases oxygen, could not compete with those using iron."}],"uid":"30678","created_gmt":"2019-07-09 16:52:08","changed_gmt":"2019-07-11 13:58:48","author":"A. Maureen Rouhi","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2019-07-11T00:00:00-04:00","iso_date":"2019-07-11T00:00:00-04:00","tz":"America\/New_York"},"extras":[],"hg_media":{"623088":{"id":"623088","type":"image","title":"Kazumi Ozaki and Christopher Reinhard","body":null,"created":"1562690817","gmt_created":"2019-07-09 16:46:57","changed":"1562690817","gmt_changed":"2019-07-09 16:46:57","alt":"","file":{"fid":"237283","name":"Ozaki and Chris Reinhard2.sq3_.jpg","image_path":"\/sites\/default\/files\/images\/Ozaki%20and%20Chris%20Reinhard2.sq3_.jpg","image_full_path":"http:\/\/www.tlwarc.hg.gatech.edu\/\/sites\/default\/files\/images\/Ozaki%20and%20Chris%20Reinhard2.sq3_.jpg","mime":"image\/jpeg","size":244049,"path_740":"http:\/\/www.tlwarc.hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/Ozaki%20and%20Chris%20Reinhard2.sq3_.jpg?itok=40rSVmCa"}}},"media_ids":["623088"],"related_links":[{"url":"https:\/\/cos.gatech.edu\/news\/early-earth-struggled-make-oxygen-complex-life","title":"Early Earth Struggled to Make Oxygen for Complex Life"}],"groups":[{"id":"1278","name":"College of Sciences"},{"id":"364801","name":"EAS"},{"id":"1214","name":"News Room"}],"categories":[{"id":"146","name":"Life Sciences and Biology"}],"keywords":[{"id":"18531","name":"photosynthesis"},{"id":"177532","name":"Earth\u0027s oxygenation"},{"id":"181683","name":"biosphere"}],"core_research_areas":[{"id":"39441","name":"Bioengineering and Bioscience"}],"news_room_topics":[{"id":"71881","name":"Science and Technology"}],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003EA. Maureen Rouhi, Ph.D.\u003Cbr \/\u003E\r\nDirector of Communications\u003Cbr \/\u003E\r\nCollege of Sciences\u003C\/p\u003E\r\n","format":"limited_html"}],"email":["maureen.rouhi@cos.gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}