海绵城市生物滞留带重金属污染特征及风险评价

生物滞留带作为海绵城市重要的净水和渗水措施，在全国海绵城市建设中得到了广泛的应用.为了探明生物滞留带重金属累积、污染和可能存在的环境风险，以全国首批海绵城市建设示范区重庆市悦来新城生物滞留带为研究对象，探讨其重金属含量与空间分布特征，利用污染系数、地质累积指数和潜在生态风险指数进行污染水平和生态环境风险评价.结果表明，悦来新城生物滞留带中除Mn外，Cu、Zn、Pb、Ni和Cd的含量平均值均超出重庆市土壤背景值的4.14、1.77、4.98、1.23和6.51倍.空间分布上，不同功能区域道路旁的生物滞留带重金属含量呈现出较大差异性，工业区道路生物滞留带中Cu、Zn、Mn、Pb、Ni和Cd的含量均显著高于其他区域生物滞留带中的同种类重金属含量（P<0.05）.污染系数和地质累积指数显示重金属的污染水平排序为：Mn

Pollution Characteristics and Risk Assessment of Heavy Metals in the Bioretention Systems of Sponge Cities

As an important water purification and seepage measure for sponge cities, biofiltration systems have been widely used in their construction in China. In order to identify the heavy metal accumulation, pollution, and its potential environmental risk in the biofiltration systems, this study examined the heavy metal contents and spatial distribution characteristics by taking the biofiltration systems of Yuelai new town, Chongqing, the first demonstration area of sponge city construction in China, as the research object, and conducted a risk evaluation of the pollution level and ecological environment in this new town using the contamination factor (CF), geo-accumulation Index (I_geo), and potential ecological risk coefficient (PERC). The results showed that, except for Mn, the average contents of Cu, Zn, Pb, Ni, and Cd in the biofiltration systems of Yuelai new town were 4.14, 1.77, 4.98, 1.23, and 6.51 times higher than the soil background values of Chongqing. In terms of spatial distribution, the contents of heavy metals in biofiltration systems along the roads in different functional areas showed great differences. The contents of Cu, Zn, Mn, Pb, Ni, and Cd in the industrial area were significantly higher than those of the same types of heavy metals in the biofiltration systems in other areas (P<0.05). The CF and I_geo showed that the pollution level of heavy metals was ranked as follows:Mn