FIG 7.

Fe conversion rates (i.e., net rates displaying simultaneous Fe[II] oxidation and Fe[III] reduction) dependent on DOC content, as determined from microcosm experiments amended with 5 mM Fe(II) or Fe(III) and 2 mM nitrate or nitrite. The theoretical net Fe conversion displays the assumption that Fe(II) oxidation would happen abiotically only by reaction with nitrite. The difference between the theoretical net Fe conversion (orange dotted line) and the actual measured Fe conversion (green marked range) represents the contribution of microbially catalyzed Fe(II) oxidation coupled to nitrate reduction.