土壤起尘悬浮颗粒物中铅赋存特性模拟

摘要

为了探索土壤起尘后悬浮颗粒物对铅的携带特性与其矿物组成、粒径尺寸之间的关联,揭示土壤起尘矿物特性及其重金属污染赋存行为,并为雾霾矿物基源特性分析及后期治理提供理论参考.通过对土壤样品进行铅污染预处理,在实验室系统内模拟风速条件下进行起尘试验,利用悬浮颗粒采样仪对经过风吹起尘后的悬浮颗粒物(TSP)、吹前表层土、吹后表层土、吹后地表土及不同粒径悬浮颗粒物进行了收集,并对悬浮颗粒物、吹前表层土、吹后表层土、吹后地表土及不同粒径悬浮颗粒物中铅的赋存状态及矿物组成与含量进行了分析.结果表明:①土壤经过风吹起尘后,悬浮颗粒物中w(Pb)为2.584 mg∕g,吹前表层土中w(Pb)为0.916 mg∕g,悬浮颗粒物中w(Pb)约是吹前表层土中w(Pb)的3倍;②不同粒径悬浮颗粒物上的w(Pb)各不相同,>10.2μm的粒径中w(Pb)为1.716 mg∕g;>4.2～10.2μm的粒径中w(Pb)为2.720 mg∕g;>2.1～4.2μm的粒径中w(Pb)为3.937 mg∕g;>1.4～2.1μm的粒径中w(Pb)为5.442 mg∕g,w(Pb)随着粒径的增加而减小;③随着悬浮颗粒物粒径的减小,黏土矿物(伊利石+绿泥石)的含量在不断的增加.研究显示,土壤起尘过程是对Pb的一种高于本底浓度的迁移过程;起尘颗粒物中w(Pb)随着悬浮颗粒物的粒径的减小而增加,呈负相关;w(Pb)与黏土矿物(伊利石+绿泥石)含量在不同粒径悬浮颗粒物上的变化规律具有一致性,呈正相关,黏土矿物(伊利石+绿泥石)对Pb具有较好的吸附性.%In order to explore the connection between characteristics of lead, which is carried by suspended particles and mineral composition and particle size of suspended particles in the dust of soil, to reveal the mineral characteristics of soil dust and the occurrence of heavy metal pollution, and provide theoretical reference for the characteristics analysis and later treatment of minerals in haze, the soil samples were pretreated with lead contamination. According to experiment of simulating wind, the total suspended particles ( TSP ) after blowing, the surface soil of sample before and after blowing, the ground soil after blowing and the different size suspended particles were collected by a suspension particle sampler. Meanwhile, the occurrence state of lead, mineral composition and content of soil were analyzed. The results show that, (1) After the production of dust by the wind, w(Pb) of TSP is 2. 584 mg∕g, w(Pb) of surface soil is 0. 787 mg∕g, and the concentration of lead in TSP is 3 times higher than the concentration in the surface soil; (2) w(Pb) of TSP of different size is different. w(Pb) of the particles with a size more than 10. 2 μm is 1. 716 mg∕g, w(Pb) of the particles with a size 4. 2-10. 2 μm is 2. 720 mg∕g, w( Pb) of the particles with a size 2. 1-4. 2μm is 3. 937 mg∕g, w( Pb) of the particles with a size 1. 4-2. 1μm is 5. 442 mg∕g. The concentration of lead in TSP decreases gradually with the increase of particle size;( 3) And then the content of clay minerals ( illite and chlorite) increase constantly with the decrease of particle size. Through the experimental research, it can be known that the dust generating process of soil is a migration in which the concentration of lead is higher than the background; The concentration of lead in suspended particles increase with the decrease of particle size, and shows a negative correlation;The variation law of the concentration of lead and the content of clay minerals ( illite and chlorite) in different particle size particles is consistent, and shows a positive correlation. Therefore, clay minerals ( illite and chlorite) have a better adsorption to lead.