降尘中重金属的形态及其在模拟酸雨下的溶出规律

使用透射、扫描电子显微镜观察大气降尘的形貌，运用BCR分级提取法和火焰原子吸收分光光度法研究大气降尘中重金属元素Cu，Pb，Zn，Cr，Ni，Mn，Fe和Cd的含量及形态分布，探讨模拟酸雨条件下大气降尘中重金属元素的溶出规律.结果表明:小粒径降尘较大粒径比表面积大，吸附能力也较强；大气降尘中重金属元素(除Fe外)均以残渣态为主， Cd含量极小，未检出；粒径相同的降尘中，Fe含量最高，主要以可还原态存在，可提取态达到70%以上；Cu，Pb，Zn，Cr，Ni和Mn均以残渣态为主；Cu，Pb和Cr在小颗粒中相对富集，造成小粒径降尘的生物危害性更大；模拟酸雨条件下，Cu，Pb，Mn，Fe和Zn的溶出量均随pH降低而增大. 

Speciation Analysis of Heavy Metals in Dustfall and Research of the Dissolving Laws in Simulated Acid Rain

TEM and SEM were used to observe the morphology of dustfall, and BCR sequential extraction procedure and flame atomic absorption spectrophotometry applied to examine the speeiation and concentration of Cu, Pb, Zn, Cr, Ni, Mn, Fe and Cd in dusffall of different diameters. The release of heavy metals in dusffall of different diameters with the effect of simulated acid rain was explored. Results sfiowed that dusffall of small diameters owed larger surface, and their absorptive capacity was stronger than that of dusffall of big diameters; There were Cu, Pb, Zn, Cr, Ni, Mn and Fe in dusffall while Cd was too few to detect. The content of Fe was the biggest, most of which was reductive and 70% of it can release from dusffall. Cu, Pb, Zn, Cr, Ni and Mn are all mainly in the residual form. The content of Cu, Pb and Cr was bigger in dustfall of smaller diameters, which had bigger endangerment to the biosphere. The release of Cu, Pb, Mn, Fe and Zn in dusffall of different diameters increased with the decrease of pH under the simulated acid rain conditions.