Abiotic oxidation of 17β-estradiol by soil manganese oxides

The degradation of 17β-estradiol (E2) in sterile soil and Mn-free soil slurries was determined. In 0.075 g ml−1 soil slurry, E2 with an initial concentration of 0.0267 μmol g−1 was rapidly degraded and near equimolar estrone (E1) accumulated. A mass balance involving E2 and E1 existed throughout the reaction. The E2 degradation was thus an oxidation process and E1 was the only product. The concurrent release of Mn(II) during E2 oxidation and a lack of E2 oxidation in Mn-free soil slurry together demonstrated that soil manganese oxides were responsible for E2 oxidation. The degree of E2 oxidation was higher at high pH than at low pH, consistent with the fact that the reaction released protons. This study suggests that manganese oxides may be used as soil amendments to effectively oxidize E2 to less potent E1 in soil.