中文摘要：

利用热扩散管TD（Thermal Denuder）与高分辨飞行时间气溶胶质谱仪（HR-To F-AMS）联用法,于2013年6—7月对华北地区国家环境空气质量评价区域点香河的大气PM1（亚微米颗粒物）及其组分〔OM（有机质）、SO42-、NO3-、NH4＋、Cl-〕进行连续在线观测,并实现了PM1不同化学组分半挥发性特征的模拟分析.结果表明：在观测期间,ρ（PM1）平均值为（47.9±47.3）μg/m3,其中OM贡献最大,达到38.2%〔ρ（OM）占ρ（PM1）的比例,下同〕,之后依次为SO42-（33.7%）、NH4＋（13.8%）、NO3-（12.3%）、Cl-（2.0%）.在PM1的各化学组分中,NO3-和Cl-的MFR（质量剩余分数）值最低（约0.40）,表明二者的半挥发性最高,当温度为50℃时,约60%的NO3-或Cl-进入气相中;SO42-的半挥发性最低,在50℃时仍有约90%的质量剩余;而OM和NH4＋的半挥发性居中.NO3-的半挥发性受大气PM1污染水平的影响,50℃时其半挥发性随着ρ（PM1）的增加而升高.当温度从50℃升至200℃时,残留有机气溶胶的O/C（原子数比）从0.47增至0.60,说明半挥发性组分多为氧化态较低的有机化合物.此外,真空动力学粒径在60～2 000 nm的颗粒物在不同粒径段表现出相近的半挥发性.大气PM1半挥发性的定量分析结果可为全面认识大气颗粒物的物化性质及污染机理提供数据,也有助于空气质量模型的完善.

英文摘要：

The coupling of a Thermal Denuder（ TD） with a High-Resolution Time-of-Flight Aerosol Mass Spectrometer（ HR-To F-AMS）was used in Xianghe,which is a regional site in Northern China,from June to July 2013,to conduct on-line measurements of the mass concentrations and semi-volatility of atmospheric submicron particles（ PM1）,including organic matter（ OM）,SO42-,NO3-,NH4＋and Cl-. The ρ（ PM1） average value was（ 47. 9 ± 47. 3） μg/m3,with ρ（ OM） accounting for 38. 2% of ρ（ PM1）,followed by ρ（ SO42-） for33. 7%,ρ（ NH4＋） for 13. 8%,ρ（ NO3-） for 12. 3% and ρ（ Cl-） for 2. 0%. It was found that the mass fractions remaining（ MFR） of NO3-and Cl-were the lowest at about 0. 40,and they had the highest semi-volatility with about 60% evaporating into the gas phase with temperature increasing to 50 ℃. SO42-showed the lowest semi-volatility,with almost 90% of its mass remaining in the particle phase at50 ℃. The semi-volatilities of OM and NH4＋were at middle levels. The semi-volatility of NO3-was affected by the pollution level of PM1,since it showed an increasing trend with the increasing of ρ（ PM1） at 50 ℃. The atomic oxygen-to-carbon ratio（ O/C） of organic aerosol（ OA） went from 0. 47 to 0. 60 when the temperature increased from 50 ℃ to 200 ℃,indicating that most of the semivolatile OA had a lower oxidation state. In addition,the semivolatility of the PM1 species with vacuum aerodynamic diameters of 60-2000 nm was not very dependent on the size. The quantitative results of semi-volatility of PM1 are essential to theresearch on the physicochemical properties and pollution mechanism of particles,as well as the validation of air quality models.