Redox reactions and phosphorus release in re‐flooded soils of an altered wetland

摘要: Summary Phosphorus loss from land can be a major factor affecting surface water quality. We studied P-release mechanisms in wetland soils that had been drained and cultivated for four decades then re-flooded. measured redox, pH solution composition two sites the field peat calcareous incubated biogeochemical microcosms. The redox measurements during 120 days of incubation resulting soil indicated main process leading to P release is reductive dissolution ferric hydroxides on which was adsorbed occluded. molar Fe:P ratio increased with period reduction below 1 first week re-flooding 15–60 after 120 days. This suggests an P-retention capacity upon reoxidation solution, whether within profile or drainage canals. Prolonged flooding calcite-poor, gypsum-rich oversaturation solutions respect hydroxyapatite occasionally β-Ca3(PO4)2(c), indicating spite large Ca concentration, rate Ca-P precipitation insufficient maintain saturation status system. In system effectively controlled activity throughout period. both cases minerals could important mechanism.