许昌市街道灰尘粒度特征及其来源分析

为获得许昌市街道灰尘的粒度特征和判断其主要来源，利用Mastersizer 2000激光粒度分析仪对2012年3月采集的许昌市街道灰尘样品进行粒度分析。结果表明，许昌市街道灰尘以粉砂为主，其次是砂粒，粘粒含量最少。粒度呈三峰型尖锐曲线，第1众数为30~145μm，第2众数为4~15μm，第3众数为0.5~1μm，平均粒径在25.42~236.15μm，分选性差，负偏。许昌市街道灰尘粒度分布与现代尘暴降尘的粒度分布模式相似，说明许昌市街道灰尘沉积是风积作用的继续，即街道灰尘主要是由低空季风环流产生的粗粒粉尘和由西风环流控制细粒粉尘混合搬运的结果，同时建筑工地就地起源的粗颗粒物质导致部分样品粒径偏大，反映出建筑行为对街道灰尘的贡献。

Street Dust Particle Size Characteristics and Its Sources Determined in Xuchang City

In order to obtain the characteristics of particle size and to determine its main sources of street dust in Xuchang city, Street dust samples collected on March, 2012 were analyzed by Mastersizer 2000 Laser Grainsize Analyzer. Results showed that: Xuchang street dust were mainly silt, followed by sand and clay, and displayed an three peaks and sharp frequency curve, the first mode was 30~145 μm, second model was 4~15 μm, third one was 0.5~1 μm, the average particle size were range from 25.42 to 236.15 μm, poor sorting and negative datum of skewness. Size distribution of Xuchang City street dust were similar to modern storm particle size patterns, which indicated that Xuchang City street dust deposition was the continuation of wind deposition, namely street dust was a mixture of coarse particles that transported by monsoon circulation and fine particles that controlled by westerly circulation, Moreover, coarse particles from the building site led samples that collected nearby to have larger particle size, which reflected the contribution of construction to street dust.