北京市地面街尘与径流中重金属的污染特征（Characteristics of Heavy Metals in Street Dusts and Urban Runoff in Beijing）

街尘作为城市各种污染物的载体和地表径流污染物的主要来源对水环境的影响日益受到关注.论文分析了北京市城区街尘与地表径流中重金属浓度和颗粒的粒径分布.结果表明:不同城市土地利用类型对街尘和径流中的重金属含量、颗粒粒径分布具有重要影响.在商业区、主要道路、住宅区、城中村4种土地利用类型中,街尘重金属浓度和地面单位面积重金属质量均以主要道路最高;径流重金属浓度由高到低顺序依次为:主要道路>城中村>居民区;主要道路和商业区街尘颗粒中细粒径占的比例较高,在全部土地利用类型的径流水样中颗粒物粒径分布差别不大;随着街尘中颗粒物粒径的减小,重金属浓度增加;街尘中小于149μm的颗粒物质量百分比和重金属浓度均较高,且在径流中这个粒径段的颗粒物含量也高,体积比达80%以上.建议在今后的城市街尘面源污染控制中应特别关注土地利用类型和街尘粒径的影响.

Characteristics of Heavy Metals in Street Dusts and Urban Runoff in Beijing

Street dusts carry various contaminants and cause urban non-point source pollution through runoff.We investigated the heavy metal contents in street dusts and runoff water.The study showed that impervious surface of different land uses significantly affected heavy metal contents and particle size distribution in street dusts and runoff water.The concentration and unit area mass of heavy metal in street dust was higher in traffic roads than in other types of land.The concentration of heavy metal in runoff follows the order: traffic road>urban village>residential district.The fine particulates in street dusts were major in traffic road and commercial area,while the particle size distributions were similar in different types of runoff water.Heavy metal concentration was higher in smaller particles.The particles with size less than 149μm had the highest mass percentage in street dusts,which accounted for more than 80% of the street dust volume in runoff.Moreover,the heavy metal concentration in these particles was highest.The research findings imply that the urban land use types and particle size distribution are key factors to affect heavy metal contamination in street dusts and runoff.