煤炭资源型城市街尘重金属污染特征及其生态风险——以宿州市为例

为了解煤炭资源型城市宿州市街尘重金属污染特征和生态风险,对23个采样点进行了12个月的连续采样。利用X射线荧光光谱分析仪对采集到的276个街尘样品进行了Cr、Cu、Mn、Pb、V和Zn等重金属含量检测。结果表明:Cr、Cu、Mn、Pb、V和Zn均值含量分别为112.9、27.5、410.3、45.2、75.6和225.3 mg/kg,除Mn和V外,其他四种重金属均超过土壤背景值。地累积指数评价结果表明,Cu、Mn和V无污染,而Cr和Pb为无污染至中度污染,Zn为中度污染。6种重金属各月份的污染负荷指数介于1~2之间,污染等级为无污染至中度污染。尽管单个重金属及6种重金属联合所致的潜在生态风险均为轻微生态风险等级,但空间分析结果表明,潜在生态风险指数的高值区一般多分布在人为活动较频繁的地段,说明重金属含量及其生态风险明显受人为活动影响。同时,风向风速对街尘重金属含量和时空变化也有重要影响。

Pollution Characteristics and Ecological Risk of Heavy Metals in Street Dust of Coal Resources Cities in China: A Case Study of Suzhou City

In order to analyze the pollution characteristics and ecological risk of heavy metals (HMs) in street dust of coal resources cities in China, 23 sampling sites in Suzhou City were selected and periodically sampled for 12 months throughout the year. A total of 276 samples were collected, and the concentrations of selected HMs (e.g. Cr, Cu, Mn, Pb, V and Zn) were examined with X-ray fluorescence spectrum analyzer. Result show that the mean concentrations of Cr, Cu, Mn, Pb, V and Zn were 112.9, 27.5, 410.3, 45.2, 75.6 and 225.3 mg/kg, respectively. With the exclusion of Mn and V, mean contents of the other four HMs are all exceeding their background values in soil of the study area. Results of geo-accumulation index reveal that Cu, Mn and V rank unpolluted, while Cr and Pb rank unpolluted to moderately polluted, and Zn ranks moderately polluted. The pollution load indexes of the selected HMs in each month are all between 1 and 2, suggesting unpolluted to moderately polluted level. Although the potential ecological risks of single heavy metal and the compound six HMs both classified as low ecological risk level totally, the spatial distribution of risk indexes (RI) shows that high content areas of RI are mainly located near the districts where human activities frequently, indicating that the concentrations of HMs and their ecological risks are significantly affected by anthropogenic activities. Meanwhile, Concentrations of HMs and their spatial and temporal distribution are also influenced by the direction and speed of wind of the study area.