An amorphous manganese oxide (AMO) and a Pb smelter-polluted agricultural soil amended with the AMO and incubated for 2 and 6 months were subjected to a pH-static leaching procedure (pH 3-8) to verify the chemical stabilization effect on metals and metalloids. The AMO stability in pure water was pH-dependent with the highest Mn release at pH 3 (47% dissolved) and the lowest at pH 8 (0.14% dissolved). Secondary rhodochrosite (MnCO3) was formed at the AMO surfaces at pH>5. The AMO dissolved significantly less after 6 months of incubation. Sequential extraction analysis indicated that "labile" fraction of As, Pb and Sb in soil significantly decreased after AMO amendment. The pH-static experiments indicated that no effect on leaching was observed for Cd and Zn after AMO treatments, whereas the leaching of As, Cu, Pb and Sb decreased down to 20%, 35%, 7% and 11% of the control, respectively. The remediation efficiency was more pronounced under acidic conditions and the time of incubation generally led to increased retention of the targeted contaminants. The AMO was found to be a promising agent for the chemical stabilization of polluted soils.

Department of Environmental Geosciences Faculty of Environmental Sciences Czech University of Life Sciences Prague Kamýcká 129 165 21 Prague 6 Suchdol Czech Republic

Institute of Geochemistry Mineralogy and Mineral Resources Faculty of Science Charles University Prague Albertov 6 128 43 Prague 2 Czech Republic

Laboratories of the Geological Institutes Faculty of Science Charles University Prague Albertov 6 128 43 Prague 2 Czech Republic

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Selected Fe and Mn (nano)oxides as perspective amendments for the stabilization of As in contaminated soils