Fig. 6. Combined results of the Fe-substrate bioavailability as Fe-uptake rate constant normalized per surface area (k_in-app/S.A.).

The bioavailability envelope’s boundaries are delineated by dotted lines, with unchelated inorganic Fe (Fe′) as its upper boundary and FeDFB as its lower boundary. Each box plot represents a different station from this study, while circles represent measurements from (37). The line across the boxes represents the median. The ends of the boxes define the 25th and 75th percentiles, and error bars define the 10th and 90th percentiles (data pooled from all depths). Literature data: Arctic: Baffin Bay (37 m), Canadian Arctic archipelago (44 m), and Beaufort Sea (10 m); North Pacific: Line-P stations P16 (25 m), P20 surface (25 m), and P20 depth (800 m); SO (Drake Passage, 100 m); Atlantic: Gulf of Mexico (2 m), GEOTRACES GA03 Atlantic Zonal Transect (100 m); equatorial Pacific (Eq. Pacific): GEOTRACES GP16 Oxygen Depleted Zone (20 m), surface (2 m), and depth (3000 m) (35). From this study, all stations are located in Antarctic waters (south of 65°S) and grouped/colored according to their location; Polynya: TMR11 (15 to 475 m) and TMR12 (15 to 500 m); Islands: TMR13 (15 to 300 m) and TMR14 (15 to 500 m); Open ocean: TMR15 (15 to 300 m) and TMR16 (15 to 500 m). Data are presented in log scale.