典型出境河流生态修复区沉积物重金属污染特征及生态风险评估  

Pollution Characteristics and Ecological Risk Assessment of Heavy Metals in Sediments of a Typical Outbound River Ecological Restoration Area

作　　者：张慧娟[1] 刘云根[1,2] 侯磊[1,2] 王妍[1,2] 齐丹卉[1,2] 

机构地区：[1]西南林业大学环境科学与工程学院,云南昆明650224 [2]西南林业大学农村污水处理研究所,云南昆明650224

出　　处：《环境科学研究》2017年第9期1415-1424,共10页Research of Environmental Sciences

基　　金：国家自然科学基金项目(51469030;31560237;31560147)

摘　　要：为综合评价河流沉积物中重金属对周围环境的生态风险及为治理重金属污染河流提供参考依据,以云南省文山州内跨境河流小白河生态修复区为研究对象,分析不同形态重金属在生态修复区沉积物中的空间分布规律,并采用潜在生态风险指数法和风险评估指数法(RAC),评价沉积物中重金属污染状况和生态风险.结果表明:(1)生态修复区内沉积物中五种重金属空间分布规律存在差异,w(As)、w(Co)、w(Cu)、w(Pb)、w(Zn)的平均值分别为937.64、16.72、156.23、73.47、1 117.47 mg/kg,并且w(As)、w(Cu)和w(Zn)沿水流方向逐渐降低,到生态修复区出口又呈明显增加的分布规律,而w(Pb)和w(Co)呈逐渐增加的分布规律.(2)生态修复区中重金属主要赋存形态以残余态为主,稳定性大小依次为As>Pb>Cu>Co>Zn.(3)根据风险评估指数法,表层沉积物中重金属对环境构成的风险依次为Zn>Co>Pb>Cu>As;根据潜在生态风险指数,As是主要的生态风险贡献因子,贡献率大于80%,具有较高的生态风险,其余重金属具有较低的生态风险.因此,在环境治理时既要考虑富集程度较严重的重金属元素,也不可忽视有效态含量较高的重金属元素给环境带来的生态风险.In order to evaluate the ecological risk of heavy metals in river sediments to the surrounding environment, and to provide a reference for the treatment of heavy metal-polluted rivers, Xiaobaihe River in Yunnan Province across the border between China and Vietnam was selected as a research object. The spatial distribution of different heavy metals in the sediments of an ecological restoration area was investigated. In addition, the potential ecological risk index and the risk assessment code （RAC） were adopted to preliminarily evaluate the contamination status and ecological risk of heavy metal contamination in the sediments. The results showed that ： （1 ） The spatial distribution of five heavy metals in the sediments of the ecological restoration area exhibited differences. The average contents of As） , w （Co）, w（Cu） , w（Pb） and w （Zn） were 937. 6 4 , 16. 7 2 , 156. 23 , 73. 47 and 1117.47 mg/kg, respectively. Along the flow direction, the distribution of the contents of As, Cu and Zn decreased gradually, and increased when reaching the outlet of the ecological restoration area, whereas those of Co and Pb gradually increased. （2） The residual state was the main speciation of the heavy metals in the ecological restoration area, and their stability followed the sequence ： As 〉 Pb 〉 Cu 〉 Co 〉 Zn. （ 3 ） According to the RAC risk assessment index, the heavy metals in the surface layer of sediment exhibited risks to the environment in the following sequence ： Zn 〉 Co 〉 Pb 〉 Cu 〉 As. Based on the potential ecological risk in d ex , As was the major contributing factor to the ecological risk , with a contribution rate was greater than 80% . As a consequence, in the process of environmental governance, we should not only consider the heavy metals which severely accumulate, but we should alsopay attention to the ecological risk brought by the relatively higher content of the effective state of heavy

关 键 词：生态修复区 重金属 沉积物 潜在生态风险指数 风险评估指数法 

分 类 号：X524[环境科学与工程—环境工程]