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The settling of resuspended lake sediment related to physicochemical properties of particles of different sizes: Implication for environmental remediation
International Journal of Sediment Research ( IF 3.6 ) Pub Date : 2020-12-03 , DOI: 10.1016/j.ijsrc.2020.11.005
Zhao Wei , Youze Xu , Yanyan Zhao , Yuanyuan Zhao , Leilei Bai , Helong Jiang , Changhui Wang

Sediment resuspension is an important way for shallow lake internal pollution to interact with the overlying water column, and the pollution risks are reasonably related to the retention of resuspended sediment particles in overlying water. In the current study, the settling of resuspended sediment particles was comprehensively investigated under different disturbances using five urban lake sediments. The results show that the particle size distributions of resuspended sediment from different lakes exhibited similar variations during settling with disturbance, although varied settling times were observed under static conditions. During settling with and without disturbance, sediment particle sizes were mainly within 8–63 μm at the initial stage, and were < 8 μm in the later stages of settling. Based on these settling characteristics, the sediment particle size was divided into sand (> 63 μm), silt (8–63 μm), and very fine silt and clay (< 8 μm) fractions. Kinetic analysis suggested that sediment settling for different particle sizes could be well described by the first- and second-order kinetic equations, especially when settling was disturbed (r2 = 0.727–0.999). The retention of resuspended sediment could be enhanced as particle sizes decreased and disturbance intensities increased. Furthermore, a water elutriation method was successfully optimized, with separation efficiencies of 56.1%–83%, to separate sediment particles into the defined three particle size fractions. The chemical compositions of sediment were found to change with different particle sizes. Typically, calcium tended to form large-size sediment, while the total contents of aluminum, iron, magnesium, and manganese showed significantly negative correlations with sediment particle sizes (p < 0.01) and tended to distribute in small-size particles (e.g., < 8 μm). Overall, the sediment particle size related settling dynamics and physicochemical properties suggested the necessity on determining the pollution of resuspended sediment at different particle sizes for restoration of shallow lakes.



中文翻译:

与不同大小颗粒的理化特性有关的重悬湖沉积物的沉降:对环境修复的意义

沉积物重悬是浅水湖泊内部污染与上覆水柱相互作用的重要途径,污染风险与上覆水中滞留的沉积物颗粒的保留有合理关系。在当前的研究中,使用五种城市湖泊沉积物,在不同的扰动下,对重悬的沉积物颗粒的沉降进行了综合研究。结果表明,尽管在静态条件下观察到了不同的沉降时间,但不同扰动的沉降过程中,来自不同湖泊的重悬沉积物的粒径分布表现出相似的变化。在有无扰动的沉降过程中,沉积物的初始粒径主要在8-63μm之内,而在沉降的后期则小于8μm。基于这些沉降特征,沉积物的粒径分为砂(> 63μm),粉砂(8-63μm)和非常细的粉砂和粘土(<8μm)级分。动力学分析表明,一阶和二阶动力学方程可以很好地描述不同粒径的沉积物沉降,特别是当沉降受到干扰时(r 2  = 0.727-0.999)。随着粒径的减小和扰动强度的增加,悬浮沉淀物的保留能力可能会增强。此外,成功地优化了水淘析方法,分离效率为56.1%–83%,可将沉积物颗粒分离为定义的三个粒径部分。发现沉积物的化学组成会随着粒径的变化而变化。通常,钙倾向于形成大尺寸的沉积物,而铝,铁,镁和锰的总含量与沉积物颗粒大小呈显着负相关(p <0.01),并且倾向于分布在小尺寸的颗粒中(例如,<8μm)。总体而言,与沉积物粒径有关的沉降动力学和理化性质表明,有必要确定不同粒径的重悬沉积物的污染,以恢复浅水湖泊。

更新日期:2020-12-03
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