Evolution of Retisol impacted by artificial drainage: What can we learn from stable Fe isotope ratios?

Iron oxides are one of the most reactive mineral phases in soils. As a consequence, their transformations can considerably affect dynamics adsorbed elements and associated soil ecosystem services. Understanding Fe soils is therefore key issue for evolution A potentially powerful tool to study Fe-oxides stable isotopes. However, there still important gaps our knowledge isotope fractionations. In order examine fractionations related each process occurring soils, we focused on drainage-influenced sequence Retisols, type characterized by clay translocation subsequent degradation redox processes inducing strong spatial segregation contrasted volumes. We combined isotopic approach at scale bulk horizon different volumes, with mineralogical analyses mass balance calculations investigate consequences drainage fractionation. showed that while were no profile scale, signatures varied significantly among volumes (δ56Fe values from −0.49 ± 0.05 0.29 0.06‰). These variations suggest main mechanisms responsible redistribution particularly accumulation during Mn oxide precipitation makes significant contribution fractionation, these Retisol differentiation. contrast, drainage-induced eluviation does not result further Retisols. The present calculated using iron (goethite, ferrihydrite) have δ56Fe close 0‰, minerals enriched heavy isotopes light This provides insight into hydromorphic offers new perspective fractionation