天山山地河流水体中微量重金属的分布特征及形态分析

为了解绿洲经济迅速发展背景下天山山地河流水体中重金属分布特征及形态特征,对乌鲁木齐-阿克苏、巴里坤-伊吾、昭苏-特克斯等3个区段河流干支流重金属Zn、Cu、Pb、Cr、As、Hg、Cd的分布、来源、污染状况及存在形态进行了分析.结果表明:1天山山地各取样河流的p H值大部分在8.0左右,为偏碱性的环境;各取样点水体的氧化还原反应电位值在150~200 m V之间,为弱氧化的环境.水质评价表明,3个采样区段河流中7种重金属的含量均低于国家Ⅰ类水质标准及WHO饮用水健康的建议标准.2多元统计分析表明,7种重金属可以归为3个主成分,其中PC1(Hg、Zn和Pb)主要受人为污染因素的影响;PC 2(Cr和As)主要受自然地质背景的影响;PC 3(Cd和Cu)同时受人为和自然因素的共同影响.3污染评价表明,天山山地河流中7种重金属的单因子污染指数值和综合污染指数值均小于1,属于安全等级,清洁水平.4形态分析表明,重金属Pb、Cd和Hg在天山中部的乌鲁木齐-阿克苏区段干支流,重金属As和Cu在天山东部的巴里坤-伊吾区段和天山西部的昭苏-特克斯区段干支流中溶解态的含量均大于50%,生物毒性较大.总体上,3个采样区段河流干支流重金属的总量及溶解态含量均较低,未造成污染.但在天山山地中部的乌鲁木齐-阿克苏区段,河流干支流中重金属Pb、Cd和Hg的总量及溶解态含量较高.应加强对该区域人类活动的合理规划以及河流水质监测,防止因人为污染而导致河流水体中重金属的含量过高,危害生态环境.

Distribution characteristics and speciation analysis of trace heavy metals in river waters of the Tianshan Mountains, China

To investigate the distribution characteristics and speciation of heavy metals in the river waters of Tianshan Mountains with rapid development of oases economy, we analyzed the distribution, sources, pollution situation and the speciation of heavy metals Zn, Cu, Pb, Cr, As, Hg and Cd in the river waters of three sections including Urumqi-Akesu, Balikun-Yiwu, and Zhaosu-Teksi. The results show that 1) the pH values of all sampling rivers were around 8.0, suggesting that these rivers were under alkaline environment. The electric potential (E_h) values of all the sampling rivers ranged from 150 to 250 mV, showing a weak oxidized environment. The water quality evaluation result shows that the average and maximum values of heavy metals Zn, Cu, As, Hg, Cd, Pb and Cr were all lower than the standards of the National Water Quality Limit (GB 3838-2002) and the Drinking Water Quality Standard of the WHO (2011); 2) results of multivariable statistic analysis show that the 7 heavy metals can be classified into three principal components: PC1 (Hg, Zn and Pb) was mainly influenced by anthropogenic pollution factors; PC2 (Cr and As) was mainly influenced by natural geological background; PC 3 (Cd and Cu) was influenced by both of the artificial and natural factors; 3) pollution evaluation result shows that the values of both single factor pollution indices and comprehensive pollution indices of the 7 tested heavy metals in surface rivers of Tianshan Mountains were less than 1, suggesting that all these rivers were at safe and clean levels; 4) the speciation analysis shows that the dissolved forms of heavy metals Pb, Cd and Hg in the rivers of the Urumqi-Akesu section, and the heavy metals As and Cu in the rivers of the Balikun-Yiwu and Zhaosu-Tekesi sections were all more than 50%, indicating a high risk of biological toxicity. In general, both the total and the dissolved contents of the 7 heavy metals in the river waters of these three sections were relatively low, however, the total and dissolved contents of heavy metals Pb, Cd and Hg were relatively high in the river waters of the Urumqi-Akesu section than those in other two sections. Therefore we should strictly restrict the unreasonable human activities and strengthen monitoring of river water quality of Tianshan Mountains to prevent the increase of heavy metal contents in the river waters and the further ecological damage of Tianshan Mountains caused by anthropogenic pollution.