Details

Autor(en) / Beteiligte

• Yu, Juhua
• Ding, Shiming
• Zhong, Jicheng
• Fan, Chengxin
• Chen, Qiuwen
• Yin, Hongbin
• Zhang, Lei
• Zhang, Yinlong

Titel

Evaluation of simulated dredging to control internal phosphorus release from sediments: Focused on phosphorus transfer and resupply across the sediment-water interface

Ist Teil von

• The Science of the total environment, 2017-08, Vol.592, p.662-673

Ort / Verlag

Netherlands: Elsevier B.V

Erscheinungsjahr

2017

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Sediment dredging is an effective restoration method to control the internal phosphorus (P) loading of eutrophic lakes. However, the core question is that the real mechanism of dredging responsible for sediment internal P release still remains unclear. In this study, we investigated the P exchange across the sediment-water interface (SWI) and the internal P resupply ability from the sediments after dredging. The study is based on a one-year field simulation study in Lake Taihu, China, using a Rhizon soil moisture sampler, high-resolution dialysis (HR-Peeper), ZrO-Chelex diffusive gradients in thin film (ZrO-Chelex DGT), and P fractionation and adsorption isotherm techniques. The results showed low concentration of labile P in the pore water with a low diffusion potential and a low resupply ability from the sediments after dredging. The calculated flux of P from the post-dredged sediments decreased by 58% compared with that of non-dredged sediments. Furthermore, the resupply in the upper 20mm of the post-dredged sediments was reduced significantly after dredging (P<0.001). Phosphorus fractionation analysis showed a reduction of 25% in the mobile P fractions in the post-dredged sediments. Further analysis demonstrated that the zero equilibrium P concentration (EPC0), partitioning coefficient (Kp), and adsorption capacity (Qmax) on the surface sediments increased after dredging. Therefore, dredging could effectively reduce the internal P resupply ability of the sediments. The reasons for this reduction are probably the lower contributions of mobile P fractions, higher retention ability, and the adsorption capacity of P for post-dredged sediments. Overall, this investigation indicated that dredging was capable of effectively controlling sediment internal P release, which could be ascribed to the removal of the surface sediments enriched with total phosphorus (TP) and/or organic matter (OM), coupled with the inactivation of P to iron (Fe) (hydr)oxides in the upper 20mm active layer. The probable mechanism of dredging on effectively controlling sediment internal P release to overlying waters is primarily to the removal of surface sediments rich in TP and/or OM combined with inactivation of P to iron (Fe) (hydr)oxides in the upper 20mm active layer sediments. Variations of SRP and soluble Fe (II) (a, c) measured by HP-Peepers and labile P and Fe (b, d) measured by DGT with depths in non-dredged and post-dredged sediments at the end of experiment. The location of the sediment-water interface is represented by zero. Values are means±SD of three replicates. Variations of adsorption isotherm parameters with sediment depths using the nonlinear form of the Langmuir equation in non-dredged and post-dredged sediment profiles at the end of experiment. [Display omitted] •Evaluation of dredging was performed based on a one-year field simulation study.•Dredging decreased the concentrations of P in pore waters and its release to water.•Dredging reduced the resupply ability of internal P in the upper 20mm sediment.•The upper 20mm sediments had higher ability to adsorb and retain P after dredging.•Iron redox cycling of the upper 20mm sediment controlled internal P regeneration.