厦门市水体表层沉积物重金属污染生态风险分析

Heavy Metal Distribution and Pollution Assessment in Surface Sediment of Water Bodies in Xiamen

沉积物是水环境的基本组成部分,其重金属含量常被作为水环境质量的重要指标之一。以厦门市为例探讨了不同城市化区域水体表层沉积物中重金属的分布特征,并采用沉积物地累积指数、Hakanson潜在生态风险指数等方法对重金属Zn、Pb、Cu、Cd、Cr、As、Hg进行环境风险评估。研究结果表明,厦门水体表层沉积物中Zn、Pb、Cu、Cd、Cr、As、Hg的含量分别为182.2、63.7、31.3、0.19、67.9、10.4、0.11 mg/kg,空间分布呈现出从城市远郊区到中心城区显著增加的趋势;依照地累积指数评价结果显示:7种重金属的污染程度顺序依次为:Hg(Pb(Zn(Cu(Cd(As(Cr;采用Hakanson提出的潜在生态危害指数法,获得厦门市主要水库重金属生态风险构成危害的顺序:Hg(Cd(Pb(As(Cu(Zn(Cr;水体表层沉积物中重金属污染水平与区域城市化水平在一定时期内呈正相关关系,这为我国快速城市化发展过程中水环境恶化问题的改善提出了警示。

Heavy metals contained are often regarded as very important parameters reflecting sediment quality since the sediment is an essential component of water environment. In this paper, the characteristics of heavy metal enrichment in the surface sediment of water bodies in Xiamen were surveyed. The environmental risk assessment was conducted systematically, by using such methods as Sediment Enrichment Factors and Hakanson potential ecological risk index. The undeftying source of heavy metals was analyzed. The results indicated that the content ranges of Zn, Pb, Cu, Cd, Cr, As and Hg were 182.2, 63.7, 31.3, 0.19, 67.9, 10.4 and 0.11 mg/kg respectively, the heavy metal content in the surface sediments of water bodies in urban areas was higher than in suburban areas, and it was very low in the rural areas. According to Geoaccumulation index Guidelines, compared to soil background values of China, the heavy metal pollution order of the surface sediment in Xiamen water bodies was Hg 〉 Pb 〉 Zn 〉 Cu 〉 Cd 〉 As 〉 Cr. In terms of the potential eco-risk on H/tkanson, it showed Hg 〉 Cd 〉 Pb 〉 As 〉 Cu 〉 Zn 〉 Cr. In some period, the heavy metal pollution in the water bodies surface sediment increased with the development of the urbanization, which warned us to pay special attention to the water environment problem in speeding urbanization in China .