北京市道路尘中重金属时空分布特征及污染程度评价

The Spatial-Temporal Distribution Characteristics and Contamination Assessments of Heavy Metals in the Road Dusts of Beijing

北京市作为我国的经济和文化中心,高速的城市化进程带来了一系列的环境问题。城市道路尘可以通过不同途径进入人体,对人体健康造成伤害。本研究采集了春、冬两季北京市6类功能区中道路尘样品46件,研究了其中Cr、Pb、Cd、As和Hg元素的含量和空间分布特征,并采用单因子指数法和内梅罗污染指数法,评价了道路尘中重金属污染程度。结果表明:除冬季As元素外,其余元素平均含量均高于北京市土壤背景值; 5种重金属元素平均含量一般为市区最高,郊区最低。单因子污染评价表明,冬、春两季各个功能区道路尘中除As元素无污染外,其余元素均具有一定程度的污染,其中Cd元素污染程度最高;冬季各功能区道路尘中重金属元素综合污染指数评价均为轻度污染;春季郊区为尚清洁,工厂区、居民区和商业区为轻度污染,休闲区和教育区为中度污染。

The fast urbanization of Beijing which is the economic and cultural center of China has brought a series of environmental problems.Humans’health can be hurt by absorbed urban road dust.46 road dust samples were collected in 6 functional areas in Beijing during spring and winter respectively to investigate the concentrations and spatial distributions of heavy metals(Cr,Pb,Cd,As and Hg)in the research.The methods of single factor index and Nemerow index were applied to evaluate the contaminated degree of road dust.The results indicated that the average concentrations of other elements were all higher than the values of the local soil background except for the element of As in winter.The max average concentrations of the 5 heavy metals in road dust were found in urban areas’values and the min ones were found in the suburban areas’values.Calculated single factor index revealed that the element of As was not exceeded in each functional area in winter and spring,whereas all the other elements caused contaminations to certain extend and the contamination of Cd was the most serious one.Results based on comprehensive pollution index showed that heavy metals in road dust were all slightly exceeded in various functional areas in winter and the results in spring showed the suburbs’areas were clean,the factory and residential and commercial areas were slightly polluted and the leisure and educational areas were moderately polluted.