北京大气气溶胶中碱性成分的研究

采用７级冲击式分级采样器采集北京春秋季大气气溶胶样品，研究不同粒径颗粒物的可溶碱性成分，详细分析了钙盐和镁盐作为碱性组分的作用，表明可以采用可溶碱性钙盐代表颗粒物的可溶碱性组分即颗粒物对降水的酸中和能力。比较春、秋两季的结果，春秋季各级颗粒物中碱性钙盐占酸溶钙盐的比例基本恒定，１～７级粒径由大至小该比例分别为０．８４、０．７６、０．７１、０．５９、０．５３、０．５７、０．２８，随着粒径增大而增大。这表明碱性钙盐及酸溶钙盐的粒径分布不随季节变化，且碱性钙盐主要分布于粗粒子中。最后，计算了北京春秋季各级颗粒物中的碱性钙盐量。

Alkaline Component of Atmospheric Particulate Matter in Beijing

Seven stage cascade impactor was used to collect samples of particulate in the spring and fall 1996 in Beijing in order to study the alkaline component of aerosol in different size range, The capacity of calcium salt and magnesium salt acting as a buffer and neutralizing the acid was compared and included that the calcium salt is the main alkaline component. The acid-soluble Ca2+ ions concentration has strong positive regression with the quantitative change in H+ ions concentration after the particulate was dissolved by acid, and the ratio of alkaline calcium salt to acid-soluble calcium salt didn't show seasonal variations, from coarse mode size range to fine mode size range (from first to seventh stage), this ratio are correspondingly 0.84, 0.76, 0.71, 0.59, 0.53, 0.57, 0.28 and value increase with the size growth. The size distribution of alkaline calcium salt and acid-soluble calcium salt in two seasons are almost same. Based on the experimental result, the content of alkaline calcium salt in particulate matter in different size range in spring and fall at Beijing are calculated.