Effects of Aqueous-Phase and Photochemical Processing on Secondary Organic Aerosol Formation and Evolution in Beijing, China
Effects of Aqueous-Phase and Photochemical Processing on Secondary Organic Aerosol Formation and Evolution in Beijing, China
复制标题
水相和光化学处理对中国北京二次有机气溶胶形成和演化的影响
DOI：
10.1021/acs.est.6b04498
复制
发表时间：
2017
影响因子：
11.4
通讯作者：
Sun Yele
中科院分区：
文献类型：
--
作者：
Xu Weiqi;Han Tingting;Du Wei;Wang Qingqing;Chen Chen;Zhao Jian;Zhang Yingjie;Li Jie;Fu Pingqing;Wang Zifa;Worsnop Douglas R.;Sun Yele
二次有机气溶胶（SOA）构成了OA的很大一部分，但仍然是一个重大的不确定性的来源，在气候模式，由于其形成机制和演变过程的不完全理解。在这里，我们评估的影响，光化学和水相处理SOA的组成和氧化程度在三个季节在北京，中国，使用高分辨率气溶胶质谱仪测量沿着正矩阵分解。我们的研究结果表明，水相处理有一个更氧化的SOA（MO-OOA）的形成占主导地位的影响，和MO-OOA OA OA的贡献大幅增加作为相对湿度或液态水含量的函数。与此相反，光化学处理中起着重要的作用，在形成较少氧化SOA（LO-OOA），如LO-OOA和奇数氧（Ox= O3+ NO2）在光化学生产期间（R2= 0.59-0.80）之间的强相关性。在相对湿度较高的时期，SOA的氧碳比也较高，这表明水相处理在改变北京SOA的氧化程度中起着重要作用。分析进一步表明，LO-OOA在秋冬季灰霾形成的早期阶段起着更重要的作用，而MO-OOA在演变的后期阶段起着更重要的作用。
Secondary organic aerosol (SOA) constitutes a large fraction of OA, yet remains a source of significant uncertainties in climate models due to incomplete understanding of its formation mechanisms and evolutionary processes. Here we evaluated the effects of photochemical and aqueous-phase processing on SOA composition and oxidation degrees in three seasons in Beijing, China, using high-resolution aerosol mass spectrometer measurements along with positive matrix factorization. Our results show that aqueous-phase processing has a dominant impact on the formation of more oxidized SOA (MO–OOA), and the contribution of MO–OOA to OA increases substantially as a function of relative humidity or liquid water content. In contrast, photochemical processing plays a major role in the formation of less oxidized SOA (LO–OOA), as indicated by the strong correlations between LO–OOA and odd oxygen (Ox= O3+ NO2) during periods of photochemical production (R2= 0.59–0.80). Higher oxygen-to-carbon ratios of SOA during periods with higher RH were also found indicating a major role of aqueous-phase processing in changing the oxidation degree of SOA in Beijing. Episodes analyses further highlight that LO–OOA plays a more important role during the early stage of the formation of autumn/winter haze episodes while MO–OOA is more significant during the later evolution period.