Interactions of Anthropogenic Pollution with Biogenic Organic Aerosols in a Forested Region of Central China

YUEMEI HAN, Xin Zhang, Lijuan Li, Jianjun Li, Yue Lin, Yan Cheng, Rui Wang, Shuyan Xing, Chongshu Zhu, Junji Cao, Institute of Earth Environment, Chinese Academy of Sciences

     Abstract Number: 13
     Working Group: Aerosol Chemistry

Abstract
Terrestrial vegetation emits huge amounts of volatile organic species and biogenic organic aerosols into the atmosphere. The presence of anthropogenic pollutants may alter their physicochemical properties and production yields, leading to large uncertainties in assessing the environmental and climate related impacts. The underlying mechanisms of anthropogenic–biogenic interactions remain to be fully elucidated. The Qinling Mountains region serves as an important natural geographical and climatic boundary between the northern and southern China. It is enriched in a variety of forested vegetation that contribute large amounts of biogenic aerosols into the atmosphere, while is often affected by anthropogenic air pollutants from the surrounding areas. In this study, the molecular composition of organic aerosols in atmospheric fine particulate matter was characterized in the northern foothills of the Qinling Mountains region during summer and winter seasons, using ultrahigh-performance liquid chromatography coupled with Orbitrap mass spectrometry. Results showed that the molecular characteristics of organic species exhibited distinct seasonal variabilities, with higher molecular weight and oxidation state but lower unsaturation degree in summer, possibly associated with more biogenic emissions and intense photochemical processes. The relative abundances of a variety of identified organic tracer species revealed that organic aerosols were substantially affected by anthropogenic sources in winter, whereas biogenic sources were more prevalent in summer. The production and transformation of organic aerosols were largely influenced by the synergistic effects of meteorology and anthropogenic pollutants in this region, which ultimately altered their molecular composition and other related characteristics. This study provides direct evidence of the anthropogenic perturbations on air quality, atmospheric chemistry, and associated climate impacts in the Qinling Mountains region.