The usefulness of Mössbauer spectroscopy for the study of iron oxidation state in pond sediments

The present study aimed to use Mossbauer spectroscopy to investigate the speciation of Fe in aquaculture pond sediments collected from the Deroua fisheries station (Morocco). The envelop of sediment layers Mossbauer spectra shows peaks that lie from -8.5 mm/s to 8.5 mm/s. In all layers spectra A, B and C, the fittings were obtained considering two sextuplets (S 1 and S 2 ) and two doublets (D 1 and D 2 ). Mossbauer Parameters analysis indicates that D 1 and D 2 are respectively attributed to structural Fe 3 and Fe 2 while S 1 and S 2 are attributed respectively to Hematite α-Fe 2 O 3 and Goethite α-FeOOH. The relative proportion of Fe 3 species decreases from 95% in the original soil to 78% in the shallow layer. Concentrations of Fe 2 + species are greater in A layer (23%) than in the original soil (5%) and in the medium horizon (8%).