用空气负离子浓度对北京地区空气清洁度进行初步评价

根据北京地区3年的空气负离子浓度时空变化的实测资料,利用空气离子单极系数及安倍空气离子评价指数对北京地区空气质量进行了初步评价. 结果表明,从市中心向近郊、远郊，空气清洁度逐渐变好;一年中以夏季空气质量最好，冬季最差;有林地区空气清洁度明显好于无林地区,阔叶林在春、夏季清洁空气的作用要好于针叶林,秋、冬季则针叶林好于阔叶林,全年平均针叶林好于阔叶林，但针叶林各季差异不大，阔叶林则夏季明显好于其他各季；溪流和瀑布等动态水在净化周围地区空气上有显著作用. 

Assessment of air cleanness degree in Beijing using negative air ion concentration as an index

Based on three years of observation on the spatio-temporal changes of negative air ion concentrations in Beijing, air quality was assessed using ion polarity ratio and air ion assessment index (CI). The results show that air cleanness degree increases gradually from city center to suburb and exurb. The air quality is best in summer and worst in winter. The air cleanness degree of forested area is better than that of non-forest area. Broad-leaved forests play a better role than coniferous forests in spring and summer for cleaning air but the opposite is true in autumn and winter. Its annual average in coniferous forests is better than that in broad-leaved forests. Its seasonal difference in coniferous forests is not obvious, but in broad-leaved forests it is obviously in summer better than in other seasons. Flowing water, such as waterfall and rivulet, plays a significant role in cleaning ambient air.