岷江下游小型集水区不同林分土壤重金属污染特征及其生态风险评价  

Heavy Metal Pollution Characteristics and Ecological Risk Assessment of Soils in Different Forest Stands of a Small Catchment at the Downstream of Minjiang River

作　　者：简毅[1] 张健[1] 杨万勤[1] 林静[1] 

机构地区：[1]四川农业大学林业生态研究所,四川温江611130

出　　处：《生态环境学报》2015年第9期1526-1533,共8页Ecology and Environmental Sciences

基　　金：国家"十二五"科技支撑计划(2011BAC09B05);四川省教育厅科技创新团队项目(11TD006);四川省应用基础项目(2012JY047);四川省科技支撑计划(12ZC0017)

摘　　要：为了解岷江下游不同林分类型土壤重金属的含量特征和污染状况,以岷江下游（五通桥段）小型集水区水杉（Metasequoia glyptostroboides）人工林、杉木（Cunninghamia lanceolata）人工林、巨桉（Eucalyptus grandis）人工林、阔叶混交林4 种林分类型为研究对象,分析林地土壤不同层次（0-10、10-40、40-80 cm）5 种重金属（As、Cd、Cu、Pb、Zn）含量,采用综合污染指数法对各林分类型土壤重金属进行评价,利用相关分析和聚类分析对其来源进行初步解析.结果表明：集水区中4 种林分类型土壤中重金属As、Cd、Cu、Pb 和Zn 的平均浓度分别为6.57、0.36、14.20、24.69、162.65 μg·g-1.土壤总体pH 值为4.73-6.49,呈酸性,有机质含量为4.32-19.72 μg·g-1,重金属As 和Cd 含量与土壤pH 值为显著负相关,5种重金属相互之间呈极显著正相关关系,与有机质也为极显著正相关关系.总体上4 种林分类型土壤重金属含量随土壤深度的增加而降低,表层土Cd 污染最严重,只存在轻微的As、Pb 和Zn 污染,但都未受到Cu 的污染.杉木人工林和水杉人工林重金属高于阔叶混交林和巨桉人工林.土壤重金属潜在生态危害程度顺序均为：Cd〉Pb〉As〉Cu〉Zn.4 种林分类型土壤重金属综合潜在的生态风险指数（RI）的范围为：102.11-247.05.表层土潜在的生态危害等级均为中等,下层土潜在的生态危害等级为中等或轻微.源解析的结果表明集水区林地土壤重金属含量受到自然源和人为源的双重影响,其中Cu 主要来自成土母质,As 和Cd 主要来自农业生产,Pb 主要来自采矿业,Zn 同时受到采矿业和农业生产等的影响.In order to understand the soil heavy metal pollution characteristics in soils of different forest stands at the downstream of Minjiang River, soil samples at the depth of 0~10, 10~40 and 40~80 cm were collected from four forest types (i.e., Metasequoia glyptostroboides plantation, Cunninghamia lanceolata plantation, Eucalyptus grandis plantation, and broad leaved mixed forest). As, Cd, Cu, Pb and Zn concentration in the soil samples were analyzed, and the comprehensive pollution index was used to assess pollution status in different forest stands. Both correlation analysis and hierarchical cluster analysis were conducted to identify the sources of heavy metals in the soils of forest stands. The results showed that average concentration of As, Cd, Cu, Pb and Zn in soils of 4 types of forest stands at the catchment were 6.57, 0.36, 14.20, 24.69 and 162.65μg·g-1, respectively. The pH with a range of 4.73~6.49 indicated that the soils were acid, and the organic matter content was from 4.32 to 19.72μg·g-1. There was a significant negative relationship between pH and As or Cd concentration; an extremely significant positive relationship between any of five heavy metal concentration and the organic content in soils, and an extremely significant positive relationship among five heavy metals were observed. In generally, the concentration of heavy metals decreased with the increase of soil depth. Surface of soils was polluted most heavily by Cd, slightly polluted by As, Pb and Zn, but not polluted by Cu in all types of forest stands. There were higher concentrations of heavy metals in the soils of M. glyptostroboides and C. lanceolata plantation than that in the soils of E. grandis plantation and broad leaved mixed forest. The potential ecological risk were in the order of Cd>Pb>As>Cu>Zn. The range of potential ecological risk index (RI) was 102.11~247.05 in above four types of forest stands. Ecological risk in the soil surface was medium, and that in subsoil was medium or slight. Hierarchical cluster analysis based o

关 键 词：集水区 林分类型 重金属 土壤 污染特征 风险评价 

分 类 号：X53[环境科学与工程—环境工程] S718.51[农业科学—林学]