硝基酚由于在近紫外-可见光区具有很强的吸光能力而受到广泛关注,这可能受到硝基酚大气过程的影响。然而,我们对硝基酚的形成和演变的认识和理解仍处于起步阶段。在本研究中,四种单硝基苯酚颗粒的混合状态(即,硝基苯酚,甲基硝基苯酚,硝基儿茶酚,和甲氧基硝基苯酚),和一个硝基多环芳烃颗粒(即,2019年11月在青岛使用单粒子气溶胶质谱仪(SPAMS)研究了硝基萘酚(NN)),中国。结果显示,第一次,单硝基酚和NN表现出不同的混合状态和昼夜变化。四种单硝基苯酚在内部彼此充分混合,和有机酸,硝酸盐,钾,还有萘。单硝基苯酚数量分数的日变化在07:00至09:00和18:00至20:00出现两个峰,中午出现一个谷。大气环境条件,包括NO2,O3,相对湿度,和温度,能显著影响单硝基苯酚的日变化。多元线性回归和随机森林回归模型表明,控制单硝基苯酚日变化的主要因素是白天的光化学反应和夜间的水相反应。与单硝基苯酚不同,约62-83%的NN与[NH4]和[H(NO3)2]-内部混合,但不是有机酸和钾。NN的日变化也与单硝基苯酚的日变化不同,通常从17:00增加到10:00,然后从11:00迅速减少到16:00。这些结果表明,NN可能具有不同于单硝基苯酚的来源和大气过程。我们推测这主要是通过光化学反应和与[NH4]混合来控制的,这可能会影响环境粒子中NN的日变化;然而,这需要进一步确认。这些发现扩展了我们目前对硝基酚在大气中的形成和演化的理解。
Nitrophenols have received extensive attention due to their strong light-absorbing ability in the near-ultraviolet-visible region, which could be influenced by the atmospheric processes of nitrophenols. However, our knowledge and understanding of the formation and evolution of nitrophenols are still in the nascent stages. In the present study, the mixing states of four mononitrophenol particles (i.e., nitrophenol, methynitrophenol, nitrocatechol, and methoxynitrophenol), and one nitropolycyclic aromatic hydrocarbon particles (i.e., nitronaphthol (NN)) were investigated using a single-particle aerosol mass spectrometer (SPAMS) in November 2019 in Qingdao, China. The results showed, for the first time, that mononitrophenols and NN exhibit different mixing states and diurnal variations. Four mononitrophenols were internally mixed well with each other, and with organic acids, nitrates, potassium, and naphthalene. The diurnal variation in the number fraction of mononitrophenols presented two peaks at 07:00 to 09:00 and 18:00 to 20:00, and a valley at noon. Atmospheric environmental conditions, including NO2, O3, relative humidity, and temperature, can significantly influence the diurnal variation of mononitrophenols. Multiple linear regression and random forest regression models revealed that the main factors controlling the diurnal variation of mononitrophenols were photochemical reactions during the day and aqueous-phase reactions during the night. Unlike mononitrophenols, about 62-83% of NN were internally mixed with [NH4]+ and [H(NO3)2]-, but not with organic acids and potassium. The diurnal variation of NN was also different from that of mononitrophenols, generally increased from 17:00 to 10:00 and then rapidly decreaed from 11:00 to 16:00. These results imply that NN may have sources and atmospheric processes that are different from mononitrophenols. We speculate that this is mostly controlled by photochemical reactions and mixing with [NH4]+, which may influence the diurnal variation of NN in the ambient particles; however, this requires further confirmation. These findings extend our current understanding of the atmospheric formation and evolution of nitrophenols.