天山山地表层土壤重金属的污染评价及生态风险分析

Assessment of Heavy Metal Pollution in the Soil of Tianshan Mountains and Analysis of Potential Ecological Risk

为了解经济迅速发展背景下天山山地土壤中重金属的污染状况和潜在生态风险,通过在天山3个典型区段采集土壤样品,测定10种微量金属的含量,然后运用多元统计分析方法、污染指数评价和潜在生态风险评估方法,并结合新疆土壤背景值和国家土壤质量二级标准进行分析和评价。结果表明:天山山地土壤中10种重金属的平均含量顺序为:Mn>Zn>Cr>Ni>Co>Cu>Pb>As>Cd>Hg;多元统计分析表明天山山地土壤中重金属Pb,Hg和Zn的含量主要受人为污染的影响,可归为"人为源因子"。土壤中重金属Cu,Ni,As,Co和Cr的含量主要受自然地质背景的影响,可归为"自然源因子"。重金属Mn和As同时受2种来源的影响;污染评价表明,天山中部的乌鲁木齐—阿克苏区段和天山东部的巴里坤—伊吾区段土壤中重金属Cd和Hg均属于中度污染水平。天山西部的昭苏—特克斯区段土壤中重金属As属于中度污染水平,其他重金属在其他区段均属于低污染水平;潜在生态风险评估表明,天山东部的巴里坤—伊吾、天山中部的乌鲁木齐—阿克苏和天山西部昭苏—特克斯3个区段土壤中10种重金属均处于低水平的生态风险。但重金属Cd和Hg在天山中部乌鲁木齐—阿克苏区段和重金属As在天山西部的昭苏—特克斯区段的生态风险指数明显高于其他区段,主要受人为污染的影响。近年来天山山地绿洲经济的发展已经造成天山中部、东部和西部一些地区土壤中重金属Cd,Hg和As的含量增高,应对此重视,加强该区域经济发展的合理规划使之与生态环境保护相协调,以保护干旱区绿洲的重要载体。

With the rapid economy development, in order to investigate the heavy metal pollution and the potential ecological risk index of heavy metals in the soil of Tianshan Mountains, China, the soil samples were collected from three typical sections of this area, and the contents of ten kinds of heavy metals in soil samples were examined. Then, the multivariate statistic analysis methods, pollution indexes methods and ecological risk evaluation methods were used in analysis combined with the background values of the heavy metals in Xinjiang and the Second National Standard of the Soil Qualities of China. The results showed that the order of the average contents of ten kinds of heavy metals in the soil of Tianshan Mountains is： Mn〉Zn〉 Cr〉Ni〉Co〉Cu〉Pb〉As〉Cd〉Hg. The contents of heavy metals Pb, Hg and Zn were mainly influenced by human activities, and they could be classified as “man made sources”. In contrast, the contents of heavy metals Cu, Ni, As, Co and Cr were mainly influenced by the natural geographical factors, and they could be classified as “natural made sources”. The heavy metals Mn and As were influenced by both of the above two kinds of factors. The pollution evaluation showed that heavy metals Cd and Hg in the soil of central Urumuqi-Akesu section and eastern Balikun-Yiwu section were within the range of moderate pollution. The heavy metal As in western Zhaosu-Tekesi section was also within the range of moderate pollution. All other heavy metals in other sections were all within the range of low pollution range. The potential ecological risk analysis showed that all the ten kinds of heavy metals in central Urumuqi-Akesu section, eastern Balikun-Yiwu section and western Zhaosu-Tekesi section were within the low level range of ecological risk, while the ecology risks of heavy metals Cd and Hg in central Urumuqi-Akesu section, and the ecology risk of heavy metal As in western Zhaosu-Tekesi section were both significantly higher than other sections, which were mainly influenced by human pollution sources. This research showed that the development of oases economy during recent years in Tianshan Mountains have resulted in significant increase in contents of the heavy metals Cd, Hg and As in the soil of some places of central, eastern and western sections of Tianshan Mountains, and this can eventually become harmful to both the ecological environment and human beings. Therefore, much attention should be paid to this and rational economic development plan for this area should be made to reasonable harmony with ecological and environmental protection in order to protect the important carrier of oasis in arid regions.