Assessing neodymium isotopes as an ocean circulation tracer in the Southwest Atlantic

The global overturning ocean circulation plays a key role in climate by distributing heat around the Earth and triggering or amplifying major changes. Neodymium (Nd) isotopes are widely used to trace present-day past changes; however, their value as tracer has been increasingly challenged studies that have focused on processes can modify seawater Nd isotope ratios (for example, interaction with particles, pore water fluxes from sediments). Southwest Atlantic represents an excellent test bed for investigating integrity of tracer, it includes northern southern hemisphere-sourced end-member masses associated circulation, Antarctic Intermediate Water, North Deep Bottom Water (AAIW, NADW, AABW, respectively) potential regional sources could impact integrity. This study reports data GEOTRACES GA02 Meridional Transect, spanning equator ∼50°S. Below pycnocline, substantial non-conservative behavior is observed only samples dominated AAIW portion transect (∼25°S equator); this appears reflect addition cratons South America Africa above pycnocline. effect not at depths directly below NADW. Otherwise, behave near-conservative mass along transect, 48% within analytical error predicted mixing, 84% 0.9 εNd-units (∼3 times error), thus confirming its most locations reconstruct