深圳秋季大气有机气溶胶来源与挥发性研究

使用热扩散管与长飞行时间气溶胶质谱联用系统对2020年深圳市秋季亚微米级气溶胶进行在线测量，获取和分析了气溶胶的化学组成及挥发性特征，并利用正矩阵因子分析法（PMF）对有机气溶胶进行了来源解析.结果显示：观测期间，气溶胶平均质量浓度为（28.3±11.1）μg/m³（9.5~76.8μg/m³），其中，有机物占比最高，为57.9%，其次为硫酸盐（24.7%）.PMF对有机气溶胶解析结果得到四类源，分别为烃类有机气溶胶（HOA）、餐饮源有关的有机气溶胶（COA）、低氧化性的氧化有机气溶胶（LO-OOA）和高氧化性的氧化有机气溶胶（MO-OOA）.HOA、COA、LO-OOA和MO-OOA平均分别占到总有机物的9.1%、27.2%、31.8%和31.9%.进一步采用NO⁺/NO₂⁺比值法和PMF方法估算有机硝酸酯（ON）浓度，两种方法估算结果相关性良好，ON的平均浓度为0.17~0.25μg/m³，占总有机气溶胶质量的1.5%~9.7%，说明其对深圳大气气溶胶贡献显著.ON与各有机气溶胶因子的相关性比对发现，其与LO-OOA相关性最高（R=0.80），说明其可能来源于新鲜的二次生成反应.挥发性研究结果得出，深圳市气溶胶主要化学组分挥发性顺序为氯盐≈无机硝酸盐 > 铵盐 > 有机物 > 有机硝酸酯 > 硫酸盐，对于有机气溶胶因子，其挥发性排序为LO-OOA > HOA > COA > MO-OOA，除了LO-OOA，其余因子挥发性与其氧化态排序一致，而LO-OOA从50~70℃组分下降最多，说明其所含组分挥发性差异最为明显.

Source identification and volatility characteristics of ambient organic aerosols in Shenzhen in autumn

Using a thermodenuder coupled with a long-time-of-flight aerosol mass spectrometry system, we conducted online measurements of submicron aerosols in Shenzhen in the fall of 2020. In addition to obtaining chemical compositions of PM₁ and analyzing their volatility characteristics, we used positive matrix factorization (PMF) method to apportion sources for organic aerosols (OA). The results showed that during the sampling period, the average mass concentration of aerosol was (28.3±11.11)μg/m³ (9.5~76.8μg/m³). Among the chemical compositions, organics contributed most to PM₁ (57.9%), sulfate was the secondary dominant composition, which accounted for 24.7% in total PM₁. PMF analysis for OA resolved four OA factors:hydrocarbon-like OA (HOA), cooking-related OA(COA), less-oxidized oxygenated OA(LO-OOA), and more-oxidized oxygenated OA(MO-OOA). The mass fractions of HOA, COA, LO-OOA and MO-OOA were 9.1%, 27.2%, 31.8% and 31.9%, respectively. Furthermore, we used two methods including NO⁺/NO₂⁺ ratio and PMF methods to estimate organonitrates (ON). The average concentration of ON was 0.17~0.25μgm^-3, accounting for 1.5%~9.7% of OA, indicating ON made a substantial contribution to aerosols in Shenzhen. Correlation analysis shows that ON were correlated bestwith LO-OOA(R=0.80), suggesting ON maybe formed via localsecondary formation. The volatility analysis revealed that the volatility sequence of the main chemical components was chloride≈inorganic nitrate>ammonium>organic matte>ON>sulfate, and the volatility sequence of the OA factors was LO-OOA> HOA> COA> MO-OOA. Except LO-OOA, the volatility sequence of other OA factors was consistent with their oxidation states. LO-OOA evaporated most from 50℃to 70℃, suggesting the significant difference of volatility existed among its compositions.