南北极大气气溶胶单颗粒成分特点研究

运用定量电子探针微区分析技术(EPMA)分别测定了采自北极新奥尔松地区(78?55′N、11?56′E)和南极乔治王岛(62?13′S、58?47′W)极昼天气下PM10大气颗粒物样品.结果表明,北极和南极大气颗粒物化学成分存在很大差异,表现出各自不同的特点.北极的颗粒类型中,“反应的海盐”和“矿物尘”分别占颗粒总数的44%和27%,“新鲜海盐”所占的比例不到10%,“反应的海盐”中以含硝酸盐的颗粒为主,反映了外来物质或人为污染对该地气溶胶影响较大;南极的颗粒类型中,“新鲜海盐”占总数的74%左右,“反应的海盐”占19%,反应的海盐全部含硫酸盐、未发现含硝酸盐的颗粒,推测与海盐反应的含硫物质来源于海洋浮游生物代谢过程产生的二甲硫醚(DMS)及其降解产物,而与人为污染无关.

Analysis of chemical compositions of individual atmospheric aerosol collected in Arctic and Antarctic area

A quantitative single particle analytical technique, low-Z particle electron probe X-ray microanalysis (EPMA) was used to characterize 2821 individual particles in 16 sets of aerosol samples collected on July 25~31, 2007 at Ny-?lesund, Svalbard (78?55′N, 11?56′E) and 1460 individual particles in 5 sets of aerosol samples collected on March 12~16, 2009 at King George Island (62?13′S, 58?47′W). There was great difference in chemical compositions between the atmospheric particles of the two sites. For the Arctic samples, aged sea salt, fresh (or genuine) sea salt, and mineral dust particles accounted for 44%, 9%, and 27%, respectively, in the examined particles (their aerodynamic diameters were in the range of 0.5~8μm). Whereas for the Antarctic samples, fresh sea salt particles accounted for 74% and aged sea salt particles containing sulfate accounted for 19% in the examined particles (their aerodynamic diameters were in the range of 1~10μm). The majority of aged sea salt particles at Ny-?lesund contained nitrate, indicating that the atmosphere was disturbed by anthropogenic air pollutants. On the contrary, all of the aged sea salt particles contained sulfate in the samples at King George Island, none of them containing nitrate. It was likely that the oxidation of dimethylsulfide (DMS) emitted from phytoplanktons in the ocean rather than anthropogenic sulfur emission was responsible for the formation of sulfate-containing aged sea salt particles, implying that the air in the Antarctic area was relatively clean, without being polluted by anthropogenic pollutants.