Extended Data Fig. 2: Characterization of siderophores in GP15 samples.

a, The ⁵⁶Fe chromatogram by LC-ICP-MS for sample at station 16, 400 m. b–e, Extracted ion chromatograms by LC-ESIMS from the same sample. Blue traces correspond to the ⁵⁶Fe–siderophore [M + H]⁺ isotopologue and red traces correspond to the less abundant ⁵⁴Fe–siderophore [M + H]⁺ isotopologue. The intensity of the ⁵⁴Fe isotopologue has been scaled by the ⁵⁶Fe/⁵⁴Fe crustal abundance ratio of 15.7. Peaks were assigned as ⁵⁶Fe–marinobactin A (m/z 985.401) (b), ⁵⁶Fe–marinobactin B (m/z 1,011.416) (c), ⁵⁶Fe–marinobactin C (m/z 1,013.432) (d) and ⁵⁶Fe–marinobactin D (m/z 1,039.452) (e).