天山北坡经济带土壤重金属来源及污染评价

为定量识别与评价天山北坡经济带中奇台、吉木萨尔、阜康等地区土壤重金属来源与生态风险，对该区域171个表层土壤中Zn、Cu、Cr、Pb、Hg、As和Cd7种常见重金属的含量进行测定.运用统计学方法、主成分分析、正定矩阵因子分解（PMF）与潜在生态风险指数进行重金属污染程度评价以及来源分析.结果表明，研究区土壤Zn、Cu与Cr之外，Pb、Hg、As和Cd分别超过了新疆土壤背景值4.1、2.0、8.0和48.0倍；与国家土壤重金属风险筛选值相比，Zn、Cr和Hg浓度在安全范围内，Cu与Pb有少部分样点污染较严重，超出筛选值，As与Cd平均值分别超出筛选值的3.09倍与19.17倍.污染来源分析结果显示研究区土壤中的重金属元素主要来自于燃煤源、交通运输、大气降尘、农工业排放和自然因素.生态风险评价结果分析表明，Zn、Cu、Cr和Pb处于轻微风险状态；Cd处于极高风险水平；73.68%的Hg处于中等风险，18.71%处于高风险；43.86%的As生态风险处于中等风险，51.46%处于高风险.综合潜在生态指数介于472~2575.69，Cd对综合潜在生态指数贡献率达到了89.24%，其次是As与Hg，表明研究区Cd对土壤生态环境危害很大，As与Hg也需要特别引起重视.

Source analysis and pollution assessment of soil heavy metals in the economic belt on the northern slope of Tianshan Mountains

In order to quantitatively identify and evaluate the sources and ecological risks of heavy metals in the Qitai, Jimsar, Fukang and other areas on the north slope of the Tianshan Mountains, we collected 171soil samples from the study area and analyzed the concentrations of Zn, Cu, Cr, Pb, Hg, As and Cd in soil. We used statistical methods of principal component analysis, positive matrix factorization (PMF) and potential ecological risk index to evaluate the degree of heavy metal pollution and to carry out source analysis. The results showed that:except for Zn, Cu, and Cr, the average concentration of Pb, Hg, As, and Cd in the soil exceeded Xinjiang soil heavy metal background values 4.1, 2.0, 8.0and 48.0times, respectively; compared with the national soil heavy metal risk screening value, the concentrations of Zn, Cr, and Hg were within the safe range. A few sample points of Cu and Pb were seriously polluted, exceeding the screening value. The average values of As and Cd exceeded the screening value by 3.09 times and 19.17times, respectively. According to the results of pollution source analysis the main pollution sources of soil in the study area are coal combustion, transportation, atmospheric dust, agricultural and industrial emissions as well as natural factors. The ecological risk assessment results showed that at all sampling points Zn, Cu, Cr, and Pb were at a slight risk state, Cd was at a very high-risk level; 73.68% of Hg was at a medium risk, 18.71% was at the high risk, 43.86% of As was at a moderate ecological risk, 51.46% was at the high risk. The comprehensive potential ecological risk index of the study area ranged from 472 to 2575.69, and the contribution rate of Cd to the comprehensive potential ecological index reached 89.24%, followed by As and Hg. The results indicated that Cd in the study area was very harmful to the soil eco-environment. As and Hg concentrations should be paid close attention.