Fig. 6: Biogeochemical model results with no dissolved inorganic δ13CDIC gradient (one box inorganic carbon cycle).
From: Marine phosphorus and atmospheric oxygen were coupled during the Great Oxidation Event

a Average δ13C of DIC in the ocean. b Atmospheric O2 concentration, c Dissolved O2 in the deep ocean relative to present oceans, d Fraction of inorganic carbon that is buried as organic carbon. PAL present atmospheric level. Grey dashed lines are redox proxy limits for atmospheric O2 level, see ref. 62.