广西锰矿区土壤重金属垂直分布和赋存形态分析

Analysis of the Vertical Distribution and Speciation of Heavy Metals in Soils from Manganese Mine Area in Guangxi

以广西某典型锰矿区中不同地域土壤为研究对象,研究了土壤中铬(Cr)、镉(Cd)、锰(Mn)3种重金属的垂直分布规律和赋存形态.采用BCR三步连续提取法对土壤中3种重金属进行形态分析以了解其潜在生态风险,采用原子吸收分光光度法分析了3种重金属元素总量,通过地累积指数(Igeo)法对重金属污染程度进行了评价.结果表明:土壤中Cr为轻度污染,Cd为严重污染,Mn的区域差异性较大,渣矿为清洁,酒店和矿场为偏重度污染.形态分析结果表明:Cr以残留态为主,潜在生物有效性较低;Cd以酸可溶态、可还原态和可氧化态为主,潜在危害性较大;Mn在酒店和矿场以可还原态为主,而在渣矿以残留态为主.3种重金属不同深度的形态分布基本保持不变,重金属污染无变化,但其本身污染严重,需采取相应措施进行土壤重金属修复.

The vertical distribution and speciation of three heavy metals （ Cr, Cd ,Mn） were studied using the soil from the different regions in a typical manganese mine area in Guangxi Province. The potential ecological risks of these metals were analyzed from the speciation by using BCR three-step sequential extraction procedure. The distribution of heavy metals were analyzed by atomic absorption spectrometry. The heavy metal pollution was assessed by Geo-accumulation Index Method （ Igeo ） . The results showed that the manganese mine area were lightly polluted by Cr, heavily polluted by Cd. The pollution of Mn varied in different region, which was clean in the slag and a little heavy in hotel and mines. The speciation analysis suggested that most of the Cr existed in residual form and was of low potential biological effectiveness. Cd mainly existed in acid-soluble, reducible, and oxidizable form and was of greater potential harmfulness. Mn existed in reducible form in the hotel and manganese mine region, and existed in residual form in the slag. There were no significant changes in vertical distributions for the three metals. However, the area was seriously polluted, it was necessary to take effective measures to remedy the polluted soils.