{"id":15797,"date":"2020-08-02T18:02:48","date_gmt":"2020-08-03T01:02:48","guid":{"rendered":"https:\/\/www.darkenergybiosphere.org\/?post_type=publication&#038;p=15797"},"modified":"2020-08-17T13:36:06","modified_gmt":"2020-08-17T20:36:06","slug":"organic-carbon-and-microbial-activity-in-marine-sediments-on-a-global-scale-throughout-the-quaternary","status":"publish","type":"publication","link":"https:\/\/www.darkenergybiosphere.org\/publication\/organic-carbon-and-microbial-activity-in-marine-sediments-on-a-global-scale-throughout-the-quaternary\/","title":{"rendered":"Organic carbon and microbial activity in marine sediments on a global scale throughout the Quaternary"},"content":{"rendered":"<p>Microbial degradation of organic carbon in marine sediments is a key driver of global element cycles on multiple time scales. However, it is not known to what depth microorganisms alter organic carbon in marine sediments or how microbial rates of organic carbon processing change with depth, and thus time since burial, on a global scale. To better understand the connection between the dynamic carbon cycle and life\u2019s limits in the deep subsurface, we have combined a number of global data sets with a reaction transport model (RTM) describing first, organic carbon degradation in marine sediments deposited throughout the Quaternary Period and second, a bioenergetic model for microbial activity. The RTM is applied globally, recognizing three distinct depositional environments \u2013 continental shelf, margin and abyssal zones. The results include the masses of particulate organic carbon, POC, stored in three sediment-depth layers: bioturbated Holocene (1.7 \u00d7 10<sup>17<\/sup>\u00a0g C), non-bioturbated Holocene (2.5 \u00d7 10<sup>18<\/sup>\u00a0g C) and Pleistocene (1.4 \u00d7 10<sup>20<\/sup>\u00a0g C) sediments. The global depth-integrated rates of POC degradation have been determined to be 1.3 \u00d7 10<sup>15<\/sup>, 1.3 \u00d7 10<sup>14<\/sup>\u00a0and 3.0 \u00d7 10<sup>14<\/sup>\u00a0g C yr<sup>-1<\/sup>\u00a0for the same three layers, respectively. A number of maps depicting the distribution of POC, as well as the fraction that has been degraded have also been generated. Using POC degradation as a proxy for microbial catabolic activity, total heterotrophic processing of POC throughout the Quaternary is estimated to be between 10<sup>-11<\/sup>\u00a0\u2013 10<sup>-6<\/sup>\u00a0g C cm<sup>-3<\/sup>\u00a0yr<sup>-1<\/sup>, depending on the time since deposition and location. Bioenergetic modeling reveals that laboratory-determined microbial maintenance powers are poor predictors of sediment biomass concentration, but that cell concentrations in marine sediments can be accurately predicted by combining bioenergetic models with the rates of POC degradation determined in this study. Our model can be used to quantitatively describe both the carbon cycle and microbial activity on a global scale for marine sediments less than 2.59 million years old.<\/p>\n","protected":false},"template":"","tags":[],"publication_type":[19],"_links":{"self":[{"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/publication\/15797"}],"collection":[{"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/publication"}],"about":[{"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/types\/publication"}],"wp:attachment":[{"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/media?parent=15797"}],"wp:term":[{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/tags?post=15797"},{"taxonomy":"publication_type","embeddable":true,"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/publication_type?post=15797"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}