College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai, 201306, China.
College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai, 201306, China.
J Environ Manage. 2019 Oct 15;248:109287. doi: 10.1016/j.jenvman.2019.109287. Epub 2019 Jul 20.
In this study, magnetite-modified activated carbon (MAC) was synthesized, characterized and used as capping and amendment materials to control sedimentary phosphorus (P) release. Batch experiments were applied to determine the behavior of phosphate adsorption and desorption on/from MAC. Sediment incubation experiments were utilized to evaluate the impact of MAC capping and addition on the mobilization of P in sediments. Sediment capping and amendment with MAC both can greatly reduce the amount of reactive soluble P (RS-P) in the overlying water (OLY-water), with a reduction efficiency of higher than 83%. MAC capping and amendment both can significantly reduce the concentrations of labile P measured by diffusive gradient in thin-films (DGT) in the upper sediment, which gives rise to in the formation of the static layer of P (P-S-Layer) in the upper sediment. The forms of P bound by MAC were mainly redox-sensitive P (P), NaOH extractable inorganic P (IP) and HCl extractable P (P), which accounted for 47.2, 18.5 and 32.9% of the total adsorbed P, respectively. Almost half of P adsorbed by MAC existed in the form of P, which is easy to be released under anoxic condition, and the retrieval of MAC from the waterbody after its application is very necessary. The concentrations of RS-P in OLY-water and mean DGT-labile P in P-S-Layer under capping condition were much less than those under amendment condition. The reduction of the apparent diffusion efflux of P across the interface between OLY-water and sediment by the MAC capping was much larger than that by the MAC amendment. Results of this work suggest that MAC capping and amendment are very promising methods for blocking the liberation of P from sediments into OLY-water, and MAC capping can achieve a higher efficiency of sedimentary P release control compared to MAC amendment.
在这项研究中，合成了磁铁矿修饰的活性炭 (MAC)，并对其进行了表征，将其用作封盖和改良材料，以控制沉积物磷（P）的释放。应用批量实验来确定磷酸盐在 MAC 上的吸附和解吸行为。利用沉积物孵育实验来评估 MAC 封盖和添加对沉积物中 P 迁移的影响。MAC 的封盖和添加都可以大大减少上覆水中（OLY-水）可反应可溶性磷（RS-P）的含量，减少效率高于 83%。MAC 的封盖和添加都可以显著降低上层沉积物中通过薄膜扩散梯度（DGT）测量的可移动磷（labile P）的浓度，从而在上层沉积物中形成磷的静态层（P-S-Layer）。MAC 结合的磷形式主要是氧化还原敏感磷（P）、NaOH 可提取无机磷（IP）和 HCl 可提取磷（P），分别占总吸附磷的 47.2%、18.5%和 32.9%。MAC 吸附的磷中几乎有一半以 P 的形式存在，在缺氧条件下容易释放，因此在应用后从水体中回收 MAC 是非常必要的。在封盖条件下，OLY 水中的 RS-P 浓度和 P-S-Layer 中的平均 DGT-可移动磷浓度都明显低于添加条件下的浓度。MAC 封盖对通过 OLY-水和沉积物界面的 P 的表观扩散通量的减少量远大于 MAC 添加的减少量。研究结果表明，MAC 封盖和添加是阻止 P 从沉积物释放到 OLY-水中的很有前途的方法，与 MAC 添加相比，MAC 封盖可以实现更高的沉积物磷释放控制效率。
