Anthropogenic pollutants induce enhancement of aerosol acidity at a mountainous background atmosphere in southern China

Gengchen Wu; Hao Wang; Chengliang Zhang; Daocheng Gong; Xiaoting Liu; Zoran Ristovski; Boguang Wang

doi:10.1016/j.scitotenv.2023.166192

Anthropogenic pollutants induce enhancement of aerosol acidity at a mountainous background atmosphere in southern China

Sci Total Environ. 2023 Dec 10:903:166192. doi: 10.1016/j.scitotenv.2023.166192. Epub 2023 Aug 9.

Authors

Gengchen Wu¹, Hao Wang², Chengliang Zhang¹, Daocheng Gong¹, Xiaoting Liu³, Zoran Ristovski⁴, Boguang Wang⁵

Affiliations

¹ Institute for Environmental and Climate Research, Jinan University, Guangzhou 511443, China; Guangdong Provincial Observation and Research Station for Atmospheric Environment and Carbon Neutrality in Nanling Forests, China.
² Institute for Environmental and Climate Research, Jinan University, Guangzhou 511443, China; Guangdong Provincial Observation and Research Station for Atmospheric Environment and Carbon Neutrality in Nanling Forests, China; JNU-QUT Joint Laboratory for Air Quality Science and Management, Jinan University, Guangzhou 511443, China. Electronic address: wanghao@jnu.edu.cn.
³ Institute for Environmental and Climate Research, Jinan University, Guangzhou 511443, China; Department of Ophthalmology, The First Affiliated Hospital, Jinan University, Guangzhou, China; JNU-QUT Joint Laboratory for Air Quality Science and Management, Jinan University, Guangzhou 511443, China.
⁴ JNU-QUT Joint Laboratory for Air Quality Science and Management, Jinan University, Guangzhou 511443, China; International Laboratory for Air Quality and Health, Queensland University of Technology, Brisbane 4001, Australia.
⁵ Institute for Environmental and Climate Research, Jinan University, Guangzhou 511443, China; Guangdong Provincial Observation and Research Station for Atmospheric Environment and Carbon Neutrality in Nanling Forests, China; JNU-QUT Joint Laboratory for Air Quality Science and Management, Jinan University, Guangzhou 511443, China. Electronic address: tbongue@jnu.edu.cn.

PMID: 37567283
DOI: 10.1016/j.scitotenv.2023.166192

Abstract

Aerosol acidity plays a crucial role in atmospheric physicochemical processes, climate change and human health, particularly in the formation of secondary organic aerosols (SOA). However, understanding the characteristics and driving factors of aerosol acidity in background mountains has been limited. In this study, we conducted intensive field measurements in the Nanling mountains during the dry and wet seasons to analyze aerosol pH characteristics and their driving factors using sensitivity tests. The mean aerosol pH in the background mountains was found to be 2.68 ± 0.55, with values ranging from 0.38 to 4.44, significantly lower than predicted values in northern China. Sensitivity tests revealed that aerosol acidity in the background atmosphere was more responsive to dominant chemical species (T-NH₃ (= NH₄⁺ + NH₃) and SO₄^2-) rather than relative humidity and temperature. Additionally, we observed that sulfate and ammonium, transported occasionally by dryer northern air masses, had a substantial impact on decreasing aerosol pH at the site. Similar to the southeastern United States, NH₄⁺/NH₃ also dominated the total buffer capacity of aerosol acidity in the Nanling mountains. The strong aerosol acidity in this area is expected to have adverse effects on regional air quality and climate by enhancing SOA formation and regulating the dry deposition of inorganic reactive nitrogen.

Keywords: Aerosol acidity; Background mountain; Buffer effect; Driving factors; Regional transport.