{"id":8186,"date":"2016-07-29T23:19:26","date_gmt":"2016-07-29T23:19:26","guid":{"rendered":"https:\/\/www.darkenergybiosphere.org\/?post_type=award&#038;p=8186"},"modified":"2020-04-01T17:08:52","modified_gmt":"2020-04-02T00:08:52","slug":"3d-spatial-mapping-of-the-energetic-return-of-1000-metabolisms-within-the-compositional-variation-of-oceanic-crusts-near-mid-ocean-ridges","status":"publish","type":"award","link":"https:\/\/www.darkenergybiosphere.org\/award\/3d-spatial-mapping-of-the-energetic-return-of-1000-metabolisms-within-the-compositional-variation-of-oceanic-crusts-near-mid-ocean-ridges\/","title":{"rendered":"Geochemical controls on organic carbon quantity and quality in the deep subsurface"},"content":{"rendered":"<p>Sediment underlying ocean gyres receives minimal input of fresh organic matter yet sustains\u00a0a small but active\u00a0heterotrophic microbial community. The concentration and composition of the organic carbon (OC) available to this deep biosphere however is unknown.\u00a0We analyzed the content and composition of OC in pelagic sediment in order to identify mechanism(s) that dictate the balance between OC preservation and utilization by microorganisms. Sediment cores from the North Atlantic gyre (KN223), South Pacific Gyre (Knox02-RR), and Peru Basin (IODP site 1231) allowed for a global comparison and a test of how sediment lithology and redox state affect OC preservation. OC was present in low concentrations in all samples (0.01\u20140.61%), at depths up to 112 meters below seafloor and estimated sediment ages of up to 50 million years. Synchrotron-based near edge X-ray absorption fine structure (NEXAFS) spectroscopy was conducted on over 100 samples, one of the first applications of NEXAFS to sedimentary environments. NEXAFS revealed\u00a0an OC reservoir dominated by amide and carboxylic functionalities in a scaffolding of O-alkyl and aliphatic carbons. Detection of extractable, extracellular proteins supports this composition and suggests that sedimentary OC is protein-derived. This composition was common across all sites and depths, implicating physical rather than chemical mechanisms in OC preservation on long timescales.\u00a0This study thereby\u00a0points to physical access rather than energy or metabolic potential as a key constraint on subsurface heterotrophic life.<\/p>\n","protected":false},"template":"","meta":[],"award_type":[9],"_links":{"self":[{"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/awards\/8186"}],"collection":[{"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/awards"}],"about":[{"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/types\/award"}],"wp:attachment":[{"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/media?parent=8186"}],"wp:term":[{"taxonomy":"award_type","embeddable":true,"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/award_type?post=8186"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}