FIG 2.
Abiotic Fe(II) production from ferrihydrite and sulfur speciation in freshwater medium to which 0.1 mM sulfide was added in 10 steps at intervals of 1 h beginning at 0.4 h. Concentrations of polysulfides and elemental sulfur (S0) were detectable only in unfiltered samples. Experiment A was conducted without cysteine, and experiment B was conducted with 2 mM cysteine. Note the different scales for Fe(II) on the secondary y axes. Sulfate data for experiment B from 2.1 to 4.2 h and from 5.6 to 9.2 h are missing.