Fig. 2.

Incubation of 1 g/L of biogenic, 13, 7 and 500 nm magnetite in bicarbonate buffer. All concentrations are expressed as percentage of total Fe concentration for total aqueous Fe²⁺ (open squares), total aqueous Fe³⁺ (open triangles), solid Fe(II) (filled squares) and solid Fe(III) (filled triangles) in a biogenic magnetite b 13 nm magnetite c 7 nm magnetite, and d 500 nm magnetite. Standard deviations of all experiments were calculated from three independent parallels