Iron speciation in peats: Chemical and spectroscopic evidence for the co-occurrence of ferric and ferrous iron in organic complexes and mineral precipitates

摘要

Highlights?Fe speciation in redox-stratified peats is reported.?Fe2+and Fe3+co-occur irrespective of redox conditions.?Complexation of Fe with organic matter is the primary stabilization mechanism.?Fe (oxy)hydroxide is identified as a secondary Fe species.AbstractThe speciation of iron (Fe) in organic matter (OM)-rich environments under in situ variable redox conditions is largely unresolved. Peatlands provide a natural setting to study Fe–OM interactions. Utilizing chemical, spectroscopic and theoretical modeling approaches, we report the chemical forms, oxidation states and local coordination environment of naturally occurring Fe in the vertically redox-stratified Manning peatlands of western New York. In addition, we report dominant carbon, sulfur and nitrogen species that can potentially stabilize the various Fe species present in these peatlands. Our re