呼和浩特市大气降尘中镉赋存形态分析

Speciation Analysis of Cadimum in Dustfall of Huhhot City

采用Tessier连续提取法对呼和浩特市不同区域的9个大气降尘样品中镉的赋存形态进行了研究。结果表明,各形态含量在总镉中所占比例由大到小排列顺序依次是:铁锰氧化物结合态>残渣态>碳酸盐结合态>强有机结合态>可交换态。大气降尘中镉的5种形态占总镉的平均质量分数由大到小为:铁锰氧化物结合态31.80%,残渣态24.42%,碳酸盐结合态19.04%,强有机结合态14.61%,可交换态10.13%;铁锰氧化物结合态是主要存在形态;铁锰氧化物结合态镉、有机结合态镉、残留态镉这三种形态镉生物有效性很低,但当环境改变时可能发生镉释放,应予以关注。汽油和煤的燃烧以及工厂排放镉能加大城市大气降尘中的镉含量。

The speciation of Cd in 9 dustfall samples from different regions of Huhhot city was studied using Tessier extraction method. The results indicated that the distribution of Cd species in dustfall was in the order of： the species bound to Fe-Mn oxides （31.80%） 〉residual species （24.42%） 〉 the species bound to carbonates （19.04%） 〉the species bound to organic （14.61%） 〉 exchangeable species （10.13%）. The bioactivity of exchangeable species and the species bound to carbonates are much higher than that of the other three species. But much attention should be paid for Cd releasing when environment changes. According to the analytical data, coal and petrol burning can increase Cd content in dusrfall of atmosphere in the city.