震后恢复重建工程对九寨沟世界自然遗产地重金属含量的影响

Effect of post-earthquake restoration and reconstruction projects on heavy metal content in the Jiuzhaigou World Natural Heritage Site

为了解九寨沟世界自然遗产地震后恢复重建工程是否造成重金属污染,在遗产地内针对性布点采集路边表土、森林表土、湖泊底泥和苔藓植物样品,测定其中主要的重金属铜(Cu)、锌(Zn)、铅(Pb)、砷(As)含量并进行比较分析,通过内梅罗综合污染指数重金属污染程度进行评价.结果显示,不同景点间路边表土的重金属含量有显著性差异(P<0.05),整体而言,五花海和芦苇海Cu、Zn、As含量较高;内梅罗综合污染指数表明路边表土呈轻度污染.森林表土中Cu、Zn含量随距离的变化呈先增加后降低的趋势,在距公路50 m处森林表土的内梅罗综合污染指数最大,属于尚清洁(警戒线)等级.湖泊底泥和苔藓植物中重金属含量均较低,小于路边表土和森林表土.整体上,九寨沟震后恢复重建工程对世界自然遗产地未产生严重重金属污染,但有必要持续监测森林表土、湖泊底泥和苔藓植物的重金属迁移和累积量.

To investigate whether post-earthquake restoration and reconstruction projects have caused heavy metal pollution in the Jiuzhaigou World Natural Heritage Site,samples of roadside topsoil,forest topsoil,lake sediments,and moss plants were collected from selected sites.The content of several heavy metals such as Cu,Zn,Pb,and As was analyzed and compared,and the Nemerow Comprehensive Pollution Index was used to evaluate the degree of pollution.The results showed significant differences in the heavy metal content of the roadside topsoil at the different sampling sites(P<0.05).Overall,Cu,Zn,and As content in Five Flower Lake and Reed Lake was higher than that in the other sites.The Nemerow Comprehensive Pollution Index classified the roadside topsoil as“slightly polluted.”Cu and Zn content in the forest topsoil increased initially and then decreased with increasing distance to the roads.The maximum value of the Nemerow Comprehensive Pollution Index occurred in the forest topsoil at a distance of 50 m to the roads,and was classified as“clean but warning.”The heavy metal content in the lake sediments and bryophytes was low and lower than that in the roadside and forest topsoil.Our study showed that post-earthquake reconstruction projects had not caused serious heavy metal pollution at the Jiuzhaigou World Natural Heritage Site as a whole;however,it is necessary to continuously monitor heavy metal migration and accumulation in the forest topsoil,lake sediments,and bryophytes.