College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai 201306, China.
College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai 201306, China.
Sci Total Environ. 2020 Oct 15;739:139749. doi: 10.1016/j.scitotenv.2020.139749. Epub 2020 Jun 3.
A magnesium/iron-based layered double hydroxide (MF-LDH) and a composite of MF-LDH and magnetite (MF-LDH@FeO) were synthesized, characterized and used as solid-phase phosphorus (P)-sorbents (SPPSs) to control the release of sedimentary P. The behavior and mechanism of phosphate adsorption onto MF-LDH and MF-LDH@FeO were studied. The effect of MF-LDH capping and amendment on the migration of P in sediments were comparatively investigated, and the impact of fabric-wrapped and unwrapped MF-LDH@FeO capping on P mobilization in sediments were also comparatively investigated. Results showed that both MF-LDH and MF-LDH@FeO had good phosphate adsorption performance, and the adsorption mechanisms included cation exchange, electrostatic attraction, ligand exchange and inner-sphere complex formation. Sediment capping and amendment using MF-LDH both could dramatically reduce the risk of the release of soluble reactive P (SRP) and diffusive gradient in thin-films-labile P (P-DGT) from sediments into overlying waters (OLY-Ws), and the MF-LDH capping had a better suppressing efficiency of sediment-P release into OLY-W than the MF-LDH amendment. Sediment capping with the fabric-wrapped and unwrapped MF-LDH@FeO both greatly decreased the risk of SRP and P-DGT released from sediment into OLY-W, and the efficiency of the prevention of SRP released from sediment into OLY-W by the fabric-wrapped MF-LDH@FeO capping layer (about 81-90%) was slightly lower than that by the unwrapped MF-LDH@FeO capping layer (about 94-99%). The reduction of P-DGT in the top sediment and the direct interception of the soluble P from pore water (POR-W) to OLY-W by the MF-LDH@FeO capping layer were the keys to the management of P released from sediment by the MF-LDH@FeO capping. From the standpoint of the efficiency of sedimentary P suppression, the convenience of application and the sustainability of sediment remediation, sediment capping with the fabric-wrapped MF-LDH@FeO is a promising approach to manage the release of sedimentary P into OLY-W.
一种镁铁基层状双氢氧化物（MF-LDH）和 MF-LDH 与磁铁矿的复合材料（MF-LDH@FeO）被合成、表征，并用作固相磷（P）吸附剂（SPPSs）以控制沉积物磷的释放。研究了磷酸盐吸附到 MF-LDH 和 MF-LDH@FeO 上的行为和机理。比较研究了 MF-LDH 封盖和添加对沉积物中磷迁移的影响，还比较研究了织物包裹和未包裹 MF-LDH@FeO 封盖对沉积物中磷迁移的影响。结果表明，MF-LDH 和 MF-LDH@FeO 均具有良好的磷酸盐吸附性能，吸附机制包括阳离子交换、静电吸引、配体交换和内球络合。用 MF-LDH 对沉积物进行封盖和添加均可显著降低可溶性反应磷（SRP）和扩散梯度薄膜-可提取磷（P-DGT）从沉积物释放到上覆水（OLY-W）中的风险，MF-LDH 封盖对抑制沉积物-P 释放到 OLY-W 的效果优于 MF-LDH 添加。用织物包裹和未包裹的 MF-LDH@FeO 对沉积物进行封盖均可极大地降低 SRP 和 P-DGT 从沉积物释放到 OLY-W 的风险，织物包裹 MF-LDH@FeO 封盖层（约 81-90%）阻止 SRP 从沉积物释放到 OLY-W 的效率略低于未包裹 MF-LDH@FeO 封盖层（约 94-99%）。MF-LDH@FeO 封盖层减少了表层沉积物中 P-DGT 的含量，以及直接将 POR-W 中的可溶磷拦截到 OLY-W 中，这是 MF-LDH@FeO 封盖层控制沉积物磷释放的关键。从抑制沉积物磷的效率、应用的便利性和沉积物修复的可持续性角度来看，用织物包裹 MF-LDH@FeO 对沉积物进行封盖是一种很有前途的管理策略，可以将沉积物中的磷释放到 OLY-W 中。
