中国城市地表灰尘中重金属的富集状况及空间分布特征

Spatial distribution and accumulation of heavy metals in urban surface dust of China

在统计中国城市地表灰尘中重金属含量的已有相关文献基础上,探讨了中国地表灰尘中Cr、Cu、Pb、Zn、Cd五种元素的空间分布特征及各省份的富集状况。搜集到的各地区地表灰尘重金属含量的研究数据分别为69、84、86、79、58个。对研究数据剔除异常值后分别进行克里金插值和统计各省份地表灰尘重金属含量的平均值,并与土壤背景值作对比计算出累积指数,得到中国地表灰尘中重金属的空间分布状况和各省份的富集水平。结果表明:中国地表灰尘中重金属含量普遍较高,且各地区重金属含量水平存在不同程度上的差异。就整体而言,Cu、Pb、Zn三种重金属含量的空间分布较为相似,由高到低均大致呈南—北走势,而Cr含量呈中部高两侧低的趋势,Cd并无明显趋势。各省份平均值与土壤背景值相比,除Cr在山东省和贵州省无富集状况以外,各省的地表灰尘中Cu、Pb、Zn、Cd均具有一定的富集。其中,湖南省的Cd和Pb均富集最为严重,分别是土壤背景值的177.95和42.82倍;Cr在福建省富集最为严重,为背景值的7.11倍;广东省的Cu富集水平最高,是背景值的10.35倍,而Zn在江西省的富集水平最高,超出背景值39.13倍。

Based on the domestic and foreign published papers about heavy metal contents of urban surface dust, the spatial variation of heavy metal contents in surface dust in China was explored. Totally, 69 studies on dust Cr, 84 on Cu, 86 on Pb, 79 on Zn and 58 on Cd were collected. Firstly, the abnormal values were picked up and removed, then the spatial distribution was obtained through Kriging method and average values in the provinces were calculated. Meanwhile, compared with the soil background values, the accumulation values of heavy metal contents were calculated. The results showed that the spatial distribution of heavy metal contents was universally high and had obvious regional difference. On the whole, the spatial distribution of Cu, Pb and Zn contents was similar, which was generally dominated by south-north trend from high contents to low contents, while the spatial distribution of Cr contents was high in the central part of the country and low in other parts, and Cd contents had no obvious trends in China. Compared with the corresponding background values of soil heavy metal concentration, nearly all provinces had higher Pb, Cu, Zn and Cd concentrations, except for the fact that Cr had no accumulation in Shandong and Guizhou provinces. The highest enrichment of Cd and Pb was found in Hunan province with 277.95 and 42.82 times of the background values, and the highest enrichment of Cr was in Fujian province with 7.11 times of the background values. The highest Cu enrichment was in Guangdong province with 1.35 times of the background values; and the highest Zn enrichment was in Jiangxi province with 39.13 times of the background values, respectively.