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[摘要]
泥沙的表面特性是了解泥沙环境效应的基础。为探究不同来源泥沙表面特性的变化规律和泥沙分级,采集了鄱阳湖入江水道和长江南京段的泥沙,依据粒径分组对泥沙颗粒的级配和表面特性(比表面积、孔体积及孔径)进行了实验分析,结果表明,鄱阳湖入江水道和长江南京段泥沙颗粒均以粘粒、粉粒和细砂粒为主,比表面积范围为3.2~25.12m2/g,属于中孔材料;泥沙颗粒的比表面积随中值粒径的增大而减小,两者呈良好的幂指数关系,即在粘粒和细粉粒范围内,比表面积随中值粒径的减少而迅速减小;与分级沙样相比,混合沙样中值粒径与比表面积的关系与分级沙样趋势相近,量值略大于分级沙样;泥沙颗粒的相对比表面积和轴比较大,当粒径大于15μm时,相对比表面积和轴比随泥沙粒径增大而缓慢增加,而当粒径小于15μm时,随泥沙粒径增大相对比表面积和轴比急剧上升。
[Key word]
[Abstract]
The surface characteristics of sediments are important to understand the environmental impact of sediments. In order to investigate the effects of grain size and grading of different origins on surface properties of sediments, sediment samples were collected from the Poyang-Yangtze Waterway and Yangtze River in Nanjing, respectively. The sediments were divided into four particle-size fractions: 0-30μm, 30-62μm, 62-90 μm, and 90-125μm, and then the surface properties (specific surface area, pore volume, and pore diameter) were investigated. The results showed that (1) the sediments in the Poyang Lake and Yangtze River are mainly clay, silt, and fine sand, and the specific surface area is from 3.2 to 25.12 m2/g, indicating that the sediments are mesoporous materials; (2) the specific surface area is in a power exponent relationship with grain size, and it decreases with the increasing of grain size for silt and clay; (3) the relationship between the median grain size of mixing sediments and specific surface area is similar to that of grading sediments, with a slightly higher magnitude; and (4) the values of axial ratio and relative surface area increase along with the increasing of median diameter, and the increasing rates of axial ratio and relative surface area are much higher when the median grain size is in the range of 0~15 μm.
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