当前位置: X-MOL 学术Atmos. Res. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Molecular composition of secondary organic aerosol from styrene under different NOx and humidity conditions
Atmospheric Research ( IF 4.5 ) Pub Date : 2021-11-29 , DOI: 10.1016/j.atmosres.2021.105950
ShanShan Yu 1, 2 , Long Jia 1, 2 , YongFu Xu 1, 2 , YuePeng Pan 1, 2
Affiliation  

Styrene is highly reactive in the atmosphere, which has been identified as a hazardous air pollutant by the Clean Air Act, and as an important secondary organic aerosol (SOA) precursor. In this study, the SOA formation from styrene under different NOx and relative humidity (RH) conditions were explored in an indoor chamber. The chemical composition of SOA was characterized using a Fourier transform infrared spectroscopy (FTIR) and a modified atmospheric pressure chemical ionization mass spectrometry (APCI-MS). The results show that the SOA yields decrease from 11.4% to 7.2% at about 70 μg m−3 SOA as RH increases from 8.5% to 62.4% in the H2O2 system; the SOA yields decrease from 1.1% to 0.7% at about 10 μg m−3 SOA as RH increases from 8.4% to 60.9% in the NOx system. In the H2O2 system, C7 and C8 series compounds are major components of SOA at both RHs. The total signal ratio of less oxidized C7 and C8 compounds (nO < 4) to the total SOA at 8.8% RH is 2.2 times higher than that at 63.3% RH. The OSc values of SOA were determined to be −0.2 at 8.8% RH and 0.04 at 63.3% RH based on MS data. It is proposed that high RH can accelerate the heterogeneous uptake of H2O2 onto particles and promote the further oxidation of less oxidized compounds in the particle phase. In the NOx system, SOA formation is significantly suppressed by the competitive reaction of RO2 with NO. The FTIR and MS results show that the main composition of SOA is organonitrates. At 8.3% RH, OH, O3 and NO3 are oxidants in the styrene-NOx irritation system. Among these oxidants, NO3 plays a minor role due to its photolysis. While at 60.9% RH, SOA formation from O3 is significantly inhibited by the reaction of stabilized Criegee intermediates (SCIs) with H2O, and SOA from the NO3 pathway is suppressed by the heterogeneous uptake of N2O5 to humid particles.



中文翻译:

不同NOx和湿度条件下苯乙烯二次有机气溶胶的分子组成

苯乙烯在大气中具有高度反应性,已被《清洁空气法》确定为有害空气污染物,并且是重要的二次有机气溶胶 (SOA) 前体。在这项研究中,在室内室中探索了在不同 NO x和相对湿度 (RH) 条件下由苯乙烯形成的 SOA 。SOA 的化学成分使用傅里叶变换红外光谱 (FTIR) 和改进的大气压化学电离质谱 (APCI-MS) 进行表征。结果表明,在H 2 O 2系统中,随着RH从8.5%增加到62.4%,SOA产率在约70 μg m -3 SOA下从11.4%减少到7.2% ;SOA 产量在约 10 μg m -3 时从 1.1% 降至 0.7%SOA 随着 RH 在 NO x系统中从 8.4% 增加到 60.9% 。在H 2 O 2系统中,C 7和C 8系列化合物是两个RH 处SOA 的主要成分。 在 8.8% RH 下,较少氧化的 C 7和 C 8化合物(n O < 4)与总 SOA的总信号比是 63.3% RH 下的 2.2 倍。基于 MS 数据,SOA 的 OSc 值在 8.8% RH 下确定为 -0.2,在 63.3% RH 下为 0.04。有人提出,高 RH 可以加速 H 2 O 2向颗粒上的异质吸收,并促进颗粒相中较少氧化的化合物的进一步氧化。在NO XRO 2与NO的竞争反应显着抑制了SOA 的形成。FTIR和MS结果表明SOA的主要成分是有机硝酸盐。在 8.3% RH 下,OH、O 3和 NO 3是苯乙烯-NO x刺激系统中的氧化剂。在这些氧化剂中,NO 3由于其光解作用而起次要作用。而在 60.9% RH 时,稳定的 Criegee 中间体 (SCIs) 与 H 2 O的反应显着抑制了O 3 的SOA 形成,并且来自 NO 3途径的SOA被 N 2 O 5对潮湿颗粒的异质吸收抑制.

更新日期:2021-12-03
down
wechat
bug