Pore water for iron isotope analysis was collected by use of rhizons, acidified and stored at 4°C until processing onshore. Processing of pore water (purification and matching) was performed at the University of Cologne, and measurements were performed on a MC-ICPMS at the Steinmann Institute in Bonn.

Processing after Henkel et al. (2016). Column separation after Schoenberg and von Blanckenburg (2005). Isotope analysis on a ThermoScientific Neptune plus Multicollector-ICP-MS (standard-sample bracketing method with IRMM-014), Isotope Geochemistry Group at MARUM-Centre for Marine Environmental Sciences, University of Bremen.