北京2009~2010年冬、春季PM2.5污染特征

针对北京地区冬季和春季PM_2.5污染特征进行研究.于2009年12月～2010年5月在城市点采集24h 大气颗粒物样品，进行颗粒物主要化学组分分析.冬季和春季颗粒物的平均质量浓度分别为（84.97±68.98）μg/m³和（65.25±45.76）μg/m³.冬季和春季颗粒物中二次组分（SNA+SOA）有重要贡献，二次组分分别占颗粒物质量浓度的49%和47%.冬春季重污染时期较强的源排放和低温、低风速、高相对湿度等不利的气象特征使得颗粒物中二次无机离子SNA（NH₄⁺、NO₃^-、SO₄^2-）的比重较干净天明显上升，其中硝酸盐贡献的增强最为显著.同时冬春季有机物中二次有机组分贡献显著.而受一次源的影响，冬春季重污染时期一次有机物的增强.

Characteristics of PM2.5 pollutionin winter and spring of Beijing during 2009~2010

A comprehensive measurement was conducted to investigate thecharacteristics of particulate matter (PM) pollution in winter and spring of Beijing. 24-hour particle samples were collected from December to May, 2009~2010, and the chemical compositions of PM_2.5 were analyzed. The average PM_2.5 massconcentrations were (84.97±68.98)μg/m³ and (65.25±45.76) μg/m³ in winter and spring, respectively. Secondary inorganic aerosols, i.e. sulfate, nitrate, andammonium (SNA), and secondary organic aerosols (SOA) were dominant theparticulate matter, with the total fraction (SNA+SOA) of 49% and 47% in winter and spring, respectively. Due to the largesource emissionand unfavorable meteorological conditions such as low temperature, low wind speed, and high relative humidity; the contributions of secondary inorganic aerosols (NH₄⁺、NO₃^-、SO₄^2-) were enhanced during thepolluted days, and the nitratewas more enhanced on polluted days. The SOA was always the most importantorganic aerosolcomponentcontributedto PM_2.5 in winter and spring. The contribution ofprimary organicaerosolsalso increased due tothe stagnant meteorological condition on polluted days.