崇明岛典型河道底泥重金属污染及农用潜在风险评价

Characteristics of Heavy Metal Pollution in a River Sediment in Chongming Island and its Potential Risk Evaluation for Agricultural Utilization

采集了崇明岛型环岛运河综合整治工程示范段(南横引河老滧港段)的底泥样品,对其中的Cd、As、Cr、Cu、Zn、Pb、Ni等重金属元素的浓度进行了分析测定。结果表明,所采集的表层底泥中Cd、As的含量均低于最低检测限。Cr、Cu、Pb、Ni的最高浓度都出现在南横引河与老滧港交汇处,但相对于全球背景值而言,其最高浓度都不超过背景值的两倍。运用Pearson相关系数法发现,Cr、Cu、Zn、Ni、Pb具有很强的相关性,即这几种重金属可能来自同一污染源。Hakanson潜在生态危害指数法评价结果发现,研究区域河道底泥重金属生态风险较小,其重金属含量均远低于污泥农用标准(GB18918—2003)以及国际上相关标准,所以示范河段疏浚底泥农用应该是安全的,但需要进行跟踪监测与评价。

Concentrations of Cd, As, Cr, Cu, Zn, Pb and Ni were analyzed in the surface sediment samples which were collected from the intersection of South Hengyin River and Laoxiao River in the Chongming Island. The concentrations of As and Cd are below the detection limits of ICP-AES. The sediments in the crosspoint of South Hengyin River and Laoxiao River show the highest concentrations of Cr, Cu, Ni and Pb, but neither is above 2 times the value of the global background. Pearson correlation analysis between Cu, Cr, Zn, Ph and Ni suggested that the investigated heavy metals might have the same sources. Heavy metals in all the sampled sediments are of low ecological risk by Hakanson＇ s potential ecological risk index method. According to the national and the other international standards for sludge agricultural utilization, the dredged sediments in the investigated rivers could be ecologically safe as agricultural land uses, but follow-up monitoring and evaluation is needed.