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.