> The presence of dissolved O2, nitrate (NO3−), phosphate (PO4−), and dissolved inorganic carbon (DIC) throughout the sedimentary sequence from the seafloor to

> The presence of dissolved O2, nitrate (NO3−), phosphate (PO4−), and dissolved inorganic carbon (DIC) throughout the sedimentary sequence from the seafloor to the volcanic basement indicates that cell abundance and activity are not limited by availability of electron acceptors or dissolved major inorganic nutrients. From the Redfield stoichiometry of net dissolved O2 reduction to net nitrate production in the sediment, the microbial cells have been inferred to consume oxygen coupled to oxidation of marine organic matter at extremely slow rates. -- D’Hondt, S. et al. Presence of oxygen and aerobic communities from sea floor to basement in deep-sea sediments. Nature Geosci. 8, 299–304 (2015).