Fig. 3: Depth profiles of Fe concentration and isotope composition.

Upper ocean (0–600 m) depth profiles of dFe and pFe concentration (a–c), and the isotope composition (d–f) for samples collected at the a, d CCE, b, e SAZ and c, f SOTS stations. See the Methods section for details on the issues and challenges involved with measuring δ56Fe on samples with very low dFe concentrations. Error bars for isotope measurements represent 2 s.e.m.