School of Atmospheric Sciences, Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies, Sun Yat-sen University, Guangzhou 510275, PR China; Guangdong Provincial Field Observation and Research Station for Climate Environment and Air Quality Change in the Pearl River Estuary, Guangzhou 510275, PR China.
Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Institute for Environmental and Climate Research, Jinan University, Guangzhou 510632, PR China.
Sci Total Environ. 2020 Jul 10;725:138228. doi: 10.1016/j.scitotenv.2020.138228. Epub 2020 Mar 31.
Aerosol acidity is of great interest due to its effects on atmospheric chemical processes and impact on human health; however, the driving factors of aerosol acidity have only been scarcely investigated. This study characterized the aerosol acidity during the wet and dry seasons in Guangzhou, China, and systematically analyzed the seasonal variation and the corresponding driving factors of aerosol acidity followed by the discussion of their impact on gas-aerosol partitioning of NH and HNO. It was demonstrated that the pH of PM was 0.08 unit lower (more acidic) during wet season than during the dry season and the aerosol acidity varied less in South China than that in North China. Additionally, our results showed that the meteorological parameters including temperature and relative humidity have larger effect on aerosol pH variation than chemical species. Particularly, the lower temperature during dry season had the positive influence (0.38 pH unit) on aerosol pH compared to the wet season; however, the negative effect due to relative humidity (RH) and chemical species resulted in a smaller seasonal variation of aerosol pH between these two seasons. The sensitivity analysis showed that the increase of temperature has negative impact (reducing pH) on aerosol pH with an almost linear relationship, while RH and chemical species represented a two-phase linear and nonlinear effect, respectively. Finally, the calculation of gas-aerosol partitioning indicated that the temperature had the largest influence on the seasonal variation of gas-aerosol partitioning for both HNO and NH followed by liquid water content and non-ideality, while aerosol acidity imposed the lowest impact, which suggests that all the parameters including meteorological and chemical species should be comprehensively evaluated to devise a PM control strategy.
气溶胶酸度因其对大气化学过程的影响及其对人类健康的影响而备受关注；然而，气溶胶酸度的驱动因素仅得到了很少的研究。本研究在中国广州的干湿两季对气溶胶酸度进行了特征描述，并系统分析了气溶胶酸度的季节性变化及其相应的驱动因素，随后讨论了它们对 NH 和 HNO 的气-粒分配的影响。结果表明，与干季相比，湿季 PM 的 pH 值低 0.08 个单位（更酸性），且中国南方的气溶胶酸度变化小于北方。此外，我们的结果表明，包括温度和相对湿度在内的气象参数对气溶胶 pH 值变化的影响大于化学物质。特别是，与湿季相比，干季较低的温度对气溶胶 pH 值有正向影响（0.38 pH 单位）；然而，相对湿度（RH）和化学物质的负面影响导致这两个季节之间气溶胶 pH 值的季节性变化较小。敏感性分析表明，温度升高对气溶胶 pH 值有负面影响（降低 pH 值），呈近乎线性关系，而 RH 和化学物质则分别呈两相线性和非线性关系。最后，气-粒分配的计算表明，温度对 HNO 和 NH 的气-粒分配的季节性变化影响最大，其次是液水含量和非理想性，而气溶胶酸度的影响最小，这表明应综合评估包括气象和化学物质在内的所有参数，以制定 PM 控制策略。
