关键词: 街道灰尘； , 重金属； , 空间分布； , 污染评价； , 包头市

Abstract: This paper studied spatial distribution and ecological risk of heavy metals in street dust of Baotou City，Inner Mongolia，China in order to provide scientific guidance to improve the situation of heavy metal pollution of city living environment based on dust sampling and experiment analysis. The concentrations of Co，Cr，Cu，Mn，Ni，Pb，Zn and V in the street dust samples collected from Baotou City were measured by X-ray fluorescence spectroscopy. The spatial distribution of heavy metals in the street dust was analyzed using the geostatistical analysis of ArcGIS，and the pollution level and ecological risk of heavy metals in the street dust was evaluated with geoaccumulation index and potential ecological risk index. The results show that the content range of Co，Cr，Cu，Mn，Ni，Pb，V and Zn are 39.7-105.8，103.0-327.7，16.3-77.1，408.9-894.3，16.1-43.5，28.6-162.7，58.6-103.2 and 47.2-136.4 mg/kg，respectively. The average content of Co，Cr，Cu，Mn，Pb，Zn and V are higher than that of the regional background value. The contents of Co，Cr and Pb in the street dust are 4-10.7，1.8-5.8 and 1.5-8.7 times of the background values，respectively. The spatial variability of the analyzed heavy metals is large. The higher concentrations of Co and Cr are found in the vicinity of some industries and enterprises，while the higher values of Cu，Zn and Pb are located in the business center and furniture and building materials market with the heavy traffic. Spatial distribution of Mn and V is similar; the higher value appeared in the eastern part of the study area. The content of Ni in most samples is low; the higher value appeared in the middle of the study area. Pollution level of the heavy metals in the street dust is Co>Cr>Pb>Zn>Cu>V>Mn>Ni. The mean I_geo of Co，Cr，Cu，Mn，Ni，Pb，V and Zn are 1.9，1.1，-0.02，-0.8，-0.8，1.1，-0.4 and 0.1,respectively. The mean I_geo of Co and Cr varies between 1 and 2，reveals moderate pollution. The mean [Igeo] and 58% I_geo of Cu is less than 0，means non-pollution. I_geo of Pb changes greatly，which is from light to moderate pollution.  I_geo of Mn，Ni and V in most of the street dust is less than 0，showing unpolluted，only individual samples appears light pollution. The mean I_geo and 63% I_geo of Zn vary between 0 and 1，showing light pollution. The potential ecological risk index of heavy metals in street dust of Kundulun District （75.5） is higher than that of the Qingshan District （69.1）. Co in the dusts belongs to middle ecological risk，while other analyzed heavy metals belong to low ecological risk. The total potential ecological risk of heavy metals in the street dust is middle.

Key words: street dust, heavy metals, spatial distribution, pollution assessment, Baotou City