Fig. 1: Preindustrial ocean biogeochemical properties.
a [CO32-]; (b), [PO43-]; (c), [O2]; (d), [CO32-]as; (e), PO4*; (f), Hydrographic sites used to generate transect profiles in (a–e) where the B-C distance is scaled down to better show meridional spans of the Atlantic (A-B) and Pacific (C-D). Note different colour shading scales in a and d, and in b and e. Red circles in (a–f) show the location of site MD97-2106. Data from GLODAPv261,62 are used to generate these transect profiles. Preindustrial DIC, derived by removing the anthropogenic component carbon from the total DIC61,62, are used to calculate [CO32-] and [CO32-]as. Deep-water [CO32-], [PO43-], and [O2] (a–c) are non-conservative and affected by biogenic matter respiration, which would complicate inferring source water conditions base on these properties. By contrast, [CO32-]as and PO4* in the ocean interior (d, e) are quasi-conservative16,17,19,20,21,22, largely determined by the endmember values of northern sourced waters (NSWs), southern sourced waters (SSWs), and their mixing proportions (see Supplementary Fig. 1 for more details).
