Characterizations and Potential Formation Pathways of Atmospheric Inorganic Ions at a National Background Site in the Northeastern Qinghai‐Tibet Plateau During Autumn Season. Issue 21 (29th October 2020)

• Record Type: Journal Article
• Authors: Han, Bin; Yang, Wen; Wang, Jing; Zhao, Xueyan; Yin, Baohui; Wang, Xinhua; Geng, Chunmei; Dou, Xiaoyan; Xu, Xun; Bai, Zhipeng
• Is Part Of: Journal of geophysical research. Volume 125:Issue 21(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-10-29
• Subjects: water‐soluble ions -- particulate matter -- Qinghai‐Tibet Plateau -- background site; Atmospheric physics -- Periodicals; Geophysics -- Periodicals; 551.5
• DOI: 10.1029/2020JD032819
• Languages: English
• ISSNs: 2169-897X

Abstract

Abstract: Atmospheric particulate matter (PM) imposes uncertain impacts on both radiative forcing and human health. Ambient PM has been comprehensively studied in China's megacities, while its compositions, sources, and characterizations in the Qinghai‐Tibet Plateau (QTP) are not fully understood. An autumn observation campaign was conducted during 1–14 October 2013 at a national background monitoring station (3, 295 m above sea level, a.s.l.) in the QTP. Real time concentrations of inorganic water‐soluble ions (WSIs) associated with PM2.5 (PM with aerodynamic diameter equal to or less than 2.5 μm) were measured in addition to PM2.5 concentrations, gaseous pollutants, and meteorological parameters. SO4 2− was the most abundant WSI (10.0 μg/m 3 ) followed by NH4 + (2.0 μg/m 3 ), and NO3 − (1.7 μg/m 3 ). Observed WSI concentrations were higher as compared to other QTP monitoring sites and some remote sites. The levels of SO4 2− were comparable to concentrations of some urban sites. The correlation analysis disclosed the relationship among WSIs and other gaseous pollutants and discussed the possibilities of biomass burning as the potential sources. Extended aerosol inorganic model (E‐AIM) model results revealed that particulate sulfate, nitrate, and ammonium (SNA) existed in both liquid and solid phases. High sulfate and nitrate oxidation ratios indicated strong secondary formation of both SO4 2− and NO3 − . By analyzing the relationship among SOR/NOR, RH, and O3, we found that both photochemical and heterogeneous reactions contributed to the formation of SO4 2−, while the conversion of NO2 to NO3 − was likely to occur via photochemical reactions in the presence of high O3 concentrations and strong sunlight. Key Points: We studied characters of WSIs associated with PM2.5 at a background site on the QTP We analyzed formation pathway of particulate SO4 2− and NO3 − at the background site Hourly levels of WSIs were measured to understand their variations on the QTP