Fig. 2: Relationship between dissolved iron, humics, iron-binding ligands, and depth in the global ocean.
From: Marine biogenic humic substances control iron biogeochemistry across the Southern Ocean
Representation of dissolved Fe (DFe) as a function of electroactive humics substances (eHS) in (a) different ocean basins and the Mediterranean Sea and (b) in the Southern Ocean. Calculated DFe saturation of eHS is shown (dotted lines) considering Suwanee river humic (HA, top) and fulvic acids (FA, bottom). Relationship between DFe and iron-binding ligands (Fe-L) is shown for (c) different ocean basins and the Mediterranean Sea, as well as for (d) the Southern Ocean. Data are colour-coded as a function of depth. The different ocean basins considered are the Arctic (triangle up20,21), North Atlantic (cross14,22), North Pacific (triangle down14), South Pacific (diamond19,24), Southern Ocean (circle14, this study) as well as the Mediterranean Sea (star22,29). All the Fe-L data were obtained using salicylaldoxime (SA) as the exchange ligands, except for in the Mediterranean Sea where 2-(2-thiazolylazo)-ρ-cresol (TAC) was used. For the Southern Ocean, our study contributes to 106 out of the 118 observations on (b), and all the data represented in (d) as no Fe-L data are available in ref. 14.
