Figure 7: Toward a mechanistic understanding of the global ocean Cr cycle.
The global array of open ocean [Cr] and δ53Cr data is shown (panel A) along with specific subsets of data highlighted to demonstrate how different processes drive the global distribution. References for these subsets are shown by superscripts. Processes which act to increase [Cr] are shown in white and processes which act to decrease [Cr] are shown in dark grey. Mixing, which may increase or decrease [Cr] depending on the point of reference, is shown in light grey. Panel B shows processes within the biological pump (surface uptake, export of biogenic particles, and regeneration at depth). Panel C shows benthic Cr fluxes. Panel D shows Cr removal in OMZs, which may follow the global trend or deviate slightly. Panel E shows mixing processes. Panel F shows processes which are unconstrained at present (hydrothermal fluxes) or which may have variable impact depending on local characteristics (riverine [Cr] and δ53Cr, estuarine mixing). The axes and ranges of all panels are identical. Data from Moos & Boyle (2019) as well as the following studies were used:1Janssen et al., 2020 (dark grey circles, panel B);2Goring-Harford et al., 2018 (dark grey diamonds, panel B; white diamonds, panel C); 3This study (white squares, panels B & C), 4Moos et al., 2020 (dark grey circles, panel D); 5Nasemann et al., 2020 (dark grey squares, panel D); 6Scheiderich et al., 2015 (light grey circles, panel E), 7Rickli et al., 2019 (light grey squares, panel E), 8Goring-Harford et al., 2020.