城乡交错带河流表层沉积物重金属污染及潜在生态风险评价

针对城乡交错带河流表层沉积物重金属污染问题，以成都市江安河为例进行污染分析和潜在生态风险评价。选取何家湾、马家市、金花桥、凉港大桥4个断面进行沉积物取样，测定其Cu、Pb、Cr、Ni、Mn、Zn、Cd共7种重金属元素的含量，并采用地积累指数法和Hakanson指数法进行重金属污染级数分析及潜在生态风险评价。研究表明:何家湾受到Zn中度污染，马家市、金花桥、凉港大桥受到Zn轻度污染，何家湾、金花桥和凉港大桥受到Cu和Cr轻度污染。潜在生态风险指数由大到小为何家湾 > 凉港大桥 > 金花桥 > 马家市，均小于40，属轻微生态风险。城市化所带来的重金属污染初见端倪，污染分布和生态风险与沿岸工农业生产分布和城市化进程相关。城乡交错带在城市化进程中应开展环境整治并加强环境管理。

Assessment on Heavy Metal Contamination and Potential Ecological Risk of Superficial Sediments from the River in Urban and Rural Ecotone

The study on heavy metal contamination and potential ecological risk assessment of the superficial sediments was carried out in the section of Jiangan River located in the typical urban and rural ectone of Chengdu. The sediment samples were taken from 4 sites of Jiangan River including Hejiawan, Majiashi, Jinhuaqiao and Lianggangdaqiao. The concentrations of Cu, Pb, Cr, Ni, Mn, Zn and Cd in the sediment samples were measured, the heavy metal contamination of the river was analyzed by geo-accumulation index, and the potential ecological risk of Jiangan River was assessed by Hakanson index. The results showed that Hejiawan was polluted by Zn in middle degree, Majiashi, Jinhuaqiao and Lianggangdaqiao were polluted by Zn in slight degree, Hejiawan, Jinhuaqiao, and Lianggangdaqiao were polluted by Cu and Cr in slight degree. Jiangan River was in slight potential ecological risk. The 4 sites in the descending order of their potential ecological risk indexes was Hejiawan, Lianggangdaqiao, Jinhuaqiao and Majiashi. This order was related to the process of urbanization and the industry-agriculture distribution along the river. The environmental protection and management of urban and rural ectone should be strengthened during the process of urbanization.