Effects Of Short-Term Aerobic Conditions On Phosphorus Mobility In Sediments

In this study, the effects of short-term aerobic conditions on phosphorus (P) mobility in sediment were investigated in the eutrophic lakes. To accomplish this, an indoor cultivation system was established and short-term cultivation (3, 8 and 15 days) was conducted under control and aerobic treatments. High-resolution diffusive gradients in thin films (DGT) and dialysis (HR-Peeper) techniques were used to determine the mobility patterns of P in sediments. The results showed that: (1) Aerobic treatment significantly increased oxygen concentrations (maximum 17.1%) in overlying water within 15 days, with no significant effects on sediment oxygen penetration depth or redox potential. Additionally, aerobic treatment inhibited soluble reactive phosphorus (SRP) and DGT-labile P release from sediment to overlying water. (2) Aerobic treatment decreased the pore water SRP and soluble Fe(II) on day 3 with no impact on sediment SRP/DGT-labile P and soluble/DGT-labile Fe on day 8 and 15. (3) Model simulation using DGT Induced Fluxes in Sediments (DIFS) showed that the pore water SRP replenishment ability of sediment particle P was lower in the aerobic group than the control group, and the sediment system equilibration time was elongated after pore water SRP decreased in the aerobic group on day 3. (4) On day 3, SRP and soluble Fe(II), DGT-labile P and DGT-labile Fe showed significant positive correlations (r > 0.888, p < 0.001), indicating that reduced pore water SRP concentration was related to decreased pore water soluble Fe(II).