Organic carbon and microbial activity in marine sediments on a global scale throughout the Quaternary

• DOI: 10.31223/osf.io/fj5tz
• Publication Date: 2020-02-20T19:58:08Z
• Authors: Douglas LaRowe; Sandra Arndt; James Bradley; Ewa Burwicz; Andrew Dale; Jan Amend
• Keywords: Abyssal zone; Particulate organic carbon; Carbon fibers; Continental Margin; Seabed

Microbial degradation of organic carbon in marine sediments is a key driver global element cycles on multiple time scales. However, it not known to what depth microorganisms alter or how microbial rates processing change with depth, and thus since burial, scale. To better understand the connection between dynamic cycle life’s limits deep subsurface, we have combined number data sets reaction transport model (RTM) describing first, deposited throughout Quaternary Period second, bioenergetic for activity. The RTM applied globally, recognizing three distinct depositional environments – continental shelf, margin abyssal zones. results include masses particulate carbon, POC, stored sediment-depth layers: bioturbated Holocene (1.7 × 10^17 g C), non-bioturbated (2.6 10^18 C) Pleistocene (1.4 1020 sediments. depth-integrated POC been determined be 6.8 10^13, 1.2 10^14 C yr-1 same layers, respectively. A maps depicting distribution as well fraction that has degraded also generated. Using proxy catabolic activity, total heterotrophic estimated 10^-11 10^-6 cm-3 yr-1, depending deposition location. Bioenergetic modeling reveals laboratory-determined maintenance powers are poor predictors sediment biomass concentration, but cell concentrations can accurately predicted by combining models this study. Our used quantitatively describe both activity scale less than 2.59 million years old.