成都经济生态区大气降尘中镉赋存形态的研究

Research about Cd Species of Dustfall in Chengdu Region

采用Tessier连续提取法对成都经济生态区不同区域的24个大气降尘样中镉的赋存形态进行了研究。研究结果表明,大气降尘中的镉主要以残留态形态存在;各形态镉在总镉中所占百分比含量由大到小排列顺序依次是:残留态,碳酸盐结合态,交换态,铁锰结合态,有机结合态;交换态镉、碳酸盐结合态镉这两种具有较高生物有效性的形态镉在总镉中所占的平均百分比含量分别是6.420%和8.917%;铁锰氧化物结合态、有机结合态、残留态镉这三种形态镉生物有效性很低,分别在总镉中所占的平均百分比含量分别是3.419%、2.365%和78.907%。通过分析可得出,汽油和煤的燃烧以及工厂排放镉能加大城市大气降尘的镉污染。

The speciation of Cd in 24 dusffall samples from Cbengdu economic region was studied by Tessier extraction method. The results indicated that the distribution of speeiation for Cd in dusffall was residual 〉 bound to carbonates 〉 exchangeable fraction 〉 bound to Fe - Mn oxides 〉 bound to organic matters. The bioactivity of exchangeable fraction and bound to carbonates forms are much higher than that of the other three forms. The percentage of exchangeable fraction and bound to carbonates fraction is 6.420% and 8.917%, respectively. The percentage of Cd bound to Fe - Mn oxides, bound to organic matters and residual is 3.419%, 2.365% and 8.907% respectively. According to the determined data and evironment, coal and petrol burning can keep dusffall of atmosphere being polluted.