3. Methods
Intermediate and deep water [Cr] and δ53Cr samples were collected on RV Investigator expeditions IN2018_V02 (Mar-2018) and IN2018_V04 (Sept-Oct 2018), ACE Legs 1 (Dec-2016 to Jan-2017) and 2 (Jan-2017 to Feb-2017), GEOTRACES section GP13 (Australian leg, May-June 2011), RV Meteor cruise M77/4 (Jan-Feb 2009), Line P cruise 2012-13 (Aug-2012), and RV Discovery cruise DY110 (Oct-Nov 2019) (Figure 1). Further analyses were performed on bottom and pore waters (IN2018V_04) and on samples from shipboard regeneration incubation experiments (IN2018V_02).