中文关键词底泥内源磷镁铁层状双金属氢氧化物添加释放控制 英文关键词sedimentinternal phosphorus loadingMg/Fe layered double hydroxidesadditionrelease control

作者	单位	E-mail
吴俊麟	上海海洋大学海洋生态与环境学院, 上海 201306	649538166@qq.com
林建伟	上海海洋大学海洋生态与环境学院, 上海 201306	jwlin@shou.edu.cn
詹艳慧	上海海洋大学海洋生态与环境学院, 上海 201306
程永前	中国环境科学研究院, 北京 100012
柏晓云	上海海洋大学海洋生态与环境学院, 上海 201306
辛慧敏	上海海洋大学海洋生态与环境学院, 上海 201306
常明玥	上海海洋大学海洋生态与环境学院, 上海 201306

中文摘要 为确定镁铁层状双金属氢氧化物（Mg/Fe-LDH）添加对水体内源磷释放的控制效果及机制，本文首先研究了Mg/Fe-LDH对水中磷酸盐的吸附特征和机制，再研究了其添加对底泥磷吸附能力的影响，以及对上覆水和间隙水中磷的影响，进而评估了吸附磷酸盐后Mg/Fe-LDH中磷的稳定性.结果发现，与准一级和准二级动力学模型相比，Mg/Fe-LDH对水中磷酸盐的吸附动力学过程更好地满足Elovich模型；与Langmuir模型相比，Freundlich和Dubinin-Radushkevich模型更加适合用于描述Mg/Fe-LDH对水中磷酸盐的等温吸附行为；当溶液pH值为4~10时，吸附容量相对较高，而当pH值由10增加到11时，吸附容量则显著下降；共存Ca²⁺和Mg²⁺对吸附起促进作用，Na⁺和Cl^-的影响可以忽略不计，而SO₄^2-和HCO₃^-则对吸附起负面影响.阴离子交换、静电吸引、配位体交换和内层配合物形成是Mg/Fe-LDH吸附水中磷酸盐的主要机制.Mg/Fe-LDH添加不仅会降低上覆水中溶解性活性磷（SRP）浓度，而且会降低间隙水中SRP浓度.Mg/Fe-LDH添加也会显著增强底泥对水中磷酸盐的吸附能力，且投加量越大，促进效果越明显.被Mg/Fe-LDH所吸附的磷酸盐主要以NH₄Cl提取态磷（NH₄Cl-P）、氧化还原敏感态磷（BD-P）和金属氧化物结合态磷（NaOH-rP）形态存在，分别占总磷的13.7%、34.0%和52.3%.被Mg/Fe-LDH所吸附的磷酸盐中大约有一半的磷会以较为稳定的形式存在，不容易被重新释放.考虑到被Mg/Fe-LDH所吸附磷酸盐中大约有一半的磷会以不稳定的形式存在，存在重新释放的风险，因此将吸附饱和后的Mg/Fe-LDH进行回收是非常必要的. 英文摘要 We determine the efficiency and mechanism of Mg/Fe layered double hydroxides (Mg/Fe-LDH) addition for the control of phosphorus (P) release from sediments by studying the adsorption behavior and mechanism of phosphate from an aqueous solution on Mg/Fe-LDH. The impact of Mg/Fe-LDH addition on the mobilization of P in sediments as well as the adsorptive removal of phosphate by sediments is investigated, and the stabilization of P bound by Mg/Fe-LDH is also evaluated. Results showed that the kinetics data of phosphate adsorption onto Mg/Fe-LDH fitted better with the Elovich kinetics model than with the pseudo-first-order and pseudo-second-order kinetics models, and that the Freundlich and Dubinin-Radushkevich models were more suitable for describing the adsorption isotherm behavior of phosphate on Mg/Fe-LDH than the Langmuir model. Phosphate adsorption possessed a wide effective pH range of 4-10. Coexisting Ca²⁺ and Mg²⁺ enhanced phosphate adsorption onto Mg/Fe-LDH, while coexisting Na⁺, K⁺, and Cl^- had negligible impacts on the phosphate adsorption. The presence of SO₄^2- and HCO₃^- in aqueous solution inhibited the adsorption of phosphate on Mg/Fe-LDH. The phosphate adsorption mechanisms were deduced to be anion exchange, electrostatic attraction, ligand exchange and inner-sphere complex formation. The addition of Mg/Fe-LDH into sediments not only greatly reduced the concentration of reactive soluble P (SRP) in the overlying water, but also significantly decreased the level of SRP in the pore water. In addition, Mg/Fe-LDH addition also increased the adsorption capacity for the sediments, and the phosphate adsorption ability for the Mg/Fe-LDH-amended sediments increased with increased amendment dosage. Almost half of the phosphate bound by Mg/Fe-LDH existed in the form of relatively stable P, i.e., metal oxide-bound P (NaOH-rP), which was difficult to release back into the water column under normal pH and anoxic conditions. Nearly half of the phosphate bound by Mg/Fe-LDH existed in the form of easily released P, i.e., NH₄Cl extractable P (NH₄Cl-P) and redox-sensitive P (BD-P), which had a high risk of re-releasing into the water column. We conclude that it is very necessary for Mg/Fe-LDH to be recycled from the sediments after the application of Mg/Fe-LDH as an amendment to control sedimentary P liberation.

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