【摘要】 采集南京市2007年夏、秋季节灰霾天和非灰霾天不同粒径大气颗粒物,分析了6月份农村秸秆焚烧对南京市大气中颗粒物和多环芳烃(PAHs)的浓度、粒径分布和分子组成的影响.结果表明,南京市大气颗粒物在灰霾天呈单模态-积聚模分布,而在其他天气条件下呈积聚模和粗模双模态分布.秸秆焚烧释放出大量细粒子和低分子量PAHs,使低环数(3~4环)PAHs的粒径分布由非灰霾天不同粒径上的均匀分布转变为灰霾天的单模态分布,总量增加了约41%,且主要富集在0.4~2.1μm的细颗粒物上;而高环数(5~6环)PAHs的粒径分布和浓度在秸秆焚烧前后均没有显著变化,呈积聚模分布.因秸秆焚烧形成的灰霾期,大气中细颗粒物和低分子量PAHs的浓度均明显提高.更多还原

【Abstract】 Atmospheric aerosols with different size in Nanjing urban area were collected during the haze and non-haze periods in summer and autumn 2007, and PAHs concentration and distribution in the summer wheat straw-burning period was also characterized. Size distribution of the particles was bimodal with one peak at the range of 0.41~2.1μm (accumulation mode) and another peak at the range of >3.0μm (coarse mode) in the two seasons except in haze days caused by the biomass burning. In contrast, a unimodal (accumulation mode) was found for the particles collected in the summer haze periods mainly due to emissions from the straw burning. Compared with those in the non-haze period, abundances of the low molecular weight (LMW) PAHs(3, 4-ring) increased by 41%, and enriched in fine particles (<2.1μm); while abundances of the high molecular weight (HMW) PAHs(5,6-ring) do not present significant differences in size distributions during haze days. Because of the wheat straw burning, both the fine particles and LMW PAHs increased remarkably.更多还原