title: pH of Aerosols in a Polluted Atmosphere: Source Contributions to Highly Acidic Aerosol.
abstract: Acidity (pH) plays a key role in the physical and chemical behavior of PM2.5. However, understanding of how specific PM sources impact aerosol pH is rarely considered. Performing source apportionment of PM2.5allows a unique link of sources pH of aerosol from the polluted city. Hourly water-soluble (WS) ions of PM2.5were measured online from December 25th, 2014 to June 19th, 2015 in a northern city in China. Five sources were resolved including secondary nitrate (41%), secondary sulfate (26%), coal combustion (14%), mineral dust (11%), and vehicle exhaust (9%). The influence of source contributions to pH was estimated by ISORROPIA-II. The lowest aerosol pH levels were found at low WS-ion levels and then increased with increasing total ion levels, until high ion levels occur, at which point the aerosol becomes more acidic as both sulfate and nitrate increase. Ammonium levels increased nearly linearly with sulfate and nitrate until approximately 20 μg m-3, supporting that the ammonium in the aerosol was more limited by thermodynamics than source limitations, and aerosol pH responded more to the contributions of sources such as dust than levels of sulfate. Commonly used pH indicator ratios were not indicative of the pH estimated using the thermodynamic model.
authors.affiliation: State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control, College of Environmental Science and Engineering, Nankai University , Tianjin 300071, China.|School of Civil and Environmental Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332-0512, United States.
authors.forename: Guoliang
authors.identifier: 0000-0001-5872-0236
authors.initials: G
authors.lastname: Shi
authors.affiliation: State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control, College of Environmental Science and Engineering, Nankai University , Tianjin 300071, China.
authors.forename: Jiao
authors.initials: J
authors.lastname: Xu
authors.affiliation: State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control, College of Environmental Science and Engineering, Nankai University , Tianjin 300071, China.
authors.forename: Xing
authors.initials: X
authors.lastname: Peng
authors.affiliation: Environmental Monitoring Center of Tianjin, Tianjin 300191, China.
authors.forename: Zhimei
authors.initials: Z
authors.lastname: Xiao
authors.affiliation: Environmental Monitoring Center of Tianjin, Tianjin 300191, China.
authors.forename: Kui
authors.initials: K
authors.lastname: Chen
authors.affiliation: State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control, College of Environmental Science and Engineering, Nankai University , Tianjin 300071, China.
authors.forename: Yingze
authors.initials: Y
authors.lastname: Tian
authors.affiliation: School of Civil and Environmental Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332-0512, United States.
authors.forename: Xinbei
authors.initials: X
authors.lastname: Guan
authors.affiliation: State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control, College of Environmental Science and Engineering, Nankai University , Tianjin 300071, China.
authors.forename: Yinchang
authors.initials: Y
authors.lastname: Feng
authors.affiliation: School of Civil and Environmental Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332-0512, United States.
authors.forename: Haofei
authors.initials: H
authors.lastname: Yu
authors.affiliation: Earth and Atmospheric Sciences, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.
authors.forename: Athanasios
authors.initials: A
authors.lastname: Nenes
authors.affiliation: School of Civil and Environmental Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332-0512, United States.
authors.forename: Armistead G
authors.initials: AG
authors.lastname: Russell
mesh_terms: D000336:Aerosols; D000393:Air Pollutants; D001272:Atmosphere; D004784:Environmental Monitoring; D006863:Hydrogen-Ion Concentration; D052638:Particulate Matter
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D052638:Particulate Matter