K. Wallmann et al., NEW PROCEDURE FOR DETERMINING REACTIVE FE(III) AND FE(II) MINERALS INSEDIMENTS, Limnology and oceanography, 38(8), 1993, pp. 1803-1812
Sediments from the River Elbe estuary and incubated sediments were ext
racted with 1 N HCI for 24 h at room temperature. The extracted ferric
and ferrous iron was determined with DC and AC polarography. Acid-vol
atile sulfide was determined from H2S trapped in aqueous zinc acetate
solution. Analysis of sediment samples and extraction residues with Mo
ssbauer spectroscopy demonstrated that the Fe oxidation state was cons
erved during extraction and polarographic determination, siderite and
vivianite were completely dissolved, and Fe(II) in chlorite was partia
lly extracted with HCl. Incubation experiments showed that extractable
Fe was almost completely oxidized to Fe(III) at the oxic sediment sur
face and reduced to Fe(II) in deeper anoxic layers within a few weeks.
Reactive Fe(III), i.e. that fraction of Fe which was reducible on the
time scale of the incubation experiment, was completely extracted wit
h HCl.