白音诺尔铅锌矿区河流沉积物重金属的形态分布特征

Morphological characteristics of heavy metals in the river sediments in the Baiyinnuoer lead-zinc mining area

为了研究内蒙古赤峰市巴林左旗白音诺尔铅锌矿区采矿对哈力黑河生态环境造成的影响,从上游向下游采集了6个河流沉积物样品,测定其pH、LOI、粒度以及As、Cu、Pb、Zn、Cd等5种重金属的总量和赋存形态,并对测试结果进行分析。研究结果表明:(1) 1#尾矿库是造成沉积物中Pb、Zn和Cd等重金属显著升高的主要原因。(2)沉积物重金属与粗粉砂(16～63μm)的相关系数为0. 79～0. 95,表明重金属易富集于粗粉砂上,而沉积物的pH和有机质对重金属总量的变化影响不显著。(3)沉积物中As和Pb以残渣态和铁锰结合态为主,分别占总量的78. 82%～89. 87%和36. 96%～78. 20%。Cu和Zn以残渣态、强有机结合态和铁锰结合态为主,分别占总量的76. 38%～85. 96%和74. 94%～90. 34%。Cd则以离子交换态、碳酸盐结合态和强有机结合态为主,占总量的51. 15%～79. 53%,而离子交换态Cd占了总量的5. 72%～49. 63%。因此,Cd对河流生态环境的潜在威胁最大。(4)离子交换态Cd与沉积物pH相关系数为-0. 813,两者呈极强负相关性。当沉积物pH由弱酸性转化为弱碱性时,离子交换态Cd含量从33. 44%降低至5. 72%,显著减小。

In order to study the impact of mining on river ecological environment in the Baiyinnuoer lead-zinc mining area,6 river sediment samples were collected from upstream to downstream,and pH,LOI,particle size and the total amount and chemical form of As,Cu,Pb,Zn and Cd were measured.The test results show that tailings pond 1 is the main cause of significant increase in contents of heavy metals such as Pb,Zn and Cd in the sediments.The correlation coefficient between heavy metals in sediments and coarse silts(16-63μm)is 0.79-0.95,indicating that heavy metals tend to be concentrated in coarse silts,while pH and organic matter in sediments have no significant influence on the total amount of heavy metals.As and Pb in sediments are mainly in the residual form and Fe-Mn oxides bound,accounting for 78.82%to 89.87%and 36.96%to 78.20%respectively.Cu and Zn are mainly in the residual form,strong organic bound and Fe-Mn oxides bound,accounting for 76.38%to 85.96%and 74.94%to 90.34%,respectively.Cd is dominated by ion-exchangeable form,carbonate bounded form and strong organic bound,accounting for 51.15%to79.53%of the total,while ion-exchangeable Cd accounts for 5.72%to 49.63%of the total.Therefore,Cd poses the greatest potential threat to the river ecological environment.The correlation coefficient between ionexchangeable Cd and pH of the sediments is-0.813,which shows a relatively strong negative correlation.The content of the ion-exchangeable Cd decreases from 33.44%to 5.72%while pH of the sediments changes from weak acidity to weak alkalinity.The results of this study are of important reference significance for the restoration and treatment of ecological environment in the Baiyinnuoer lead-zinc mining area.