Cu^(2+)污染原状黄土的物化及结构特性

The physicochemical and structural characteristics of Cu^(2+)contaminated undisturbed loess

为制定环境保护和土壤污染防治和修复策略,以及为污染场地工程建设提供理论支撑,该文研究了Cu^(2+)对原状黄土物化特性及结构特性的影响。通过制备不同掺量的Cu^(2+)污染黄土试样,进行了粒径分布、CaCO_(3)含量和pH值的测定。利用扫描电镜和激光粒度仪获得试样的SEM图像和粉粒各粒径含量,并借助分形理论深入分析了Cu^(2+)对原状黄土微观结构的影响机理。对Cu^(2+)污染的原状黄土试样进行了压缩试验,并对试样的综合结构势进行了分析。结果表明,随着Cu^(2+)掺量的增大,黏粒含量表现为先增后减,再增再减的趋势,粉粒含量则表现为先减后增,再减再增,砂粒含量保持不变;CaCO_(3)的含量呈线性减小;pH值先迅速减小,后保持不变;污染黄土试样的综合结构势先增大后减小,之后再增大再减小。总体而言,重金属Cu^(2+)的掺入,导致土壤pH值降低,主要胶结物质碳酸钙被溶解,而又因黏粒之间的静电引力和范德华力,黏粒聚集体的形态和成分发生变化,从而影响了土体的密实度和结构强度。

The effects of Cu^(2+)on the physicochemical and structural characteristics of undisturbed loess were studied in order to formulate effective strategies for environmental protection,soil pollution prevention and remediation,and to provide theoretical support for the engineering construction of contaminated sites.The particle size distribution,CaCO_(3) content and pH value of Cu^(2+)contaminated loess samples were determined.The SEM images and particle size contents of the samples were obtained by scanning electron microscopy and laser particle size analyzer.The influence mechanism of Cu^(2+)on the microstructure of undisturbed loess was analyzed by means of fractal theory.The compression test of Cu^(2+)contaminated undisturbed loess was carried out,and the comprehensive structural potential of the sample was analyzed.The results show that with the increase of Cu^(2+)content,the clay content increases first and then decreases,and then increases and then decreases,while the powder content decreases first and then increases,and the sand content remains unchanged.The content of CaCO_(3) decreased linearly.The pH value decreases rapidly at first,and then remains unchanged.The comprehensive structural potential of the contaminated loess samples first increased and then decreased,and then increased and then decreased.In general,the incorporation of heavy metal Cu^(2+)leads to the decrease of soil pH value,the dissolution of the main cementing material calcium carbonate,and the change of the form and composition of clay aggregates due to the electrostatic attraction and van der Waals forces between clay particles,thus affecting the compactness and structural strength of soil.