Isotopic imprints of aerosol ammonium over the north China plain

Abubakari Said Mgelwa; Linlin Song; Meiyi Fan; Zhengjie Li; Yanlin Zhang; Yunhua Chang; Yuepeng Pan; Geshere Abdisa Gurmesa; Dongwei Liu; Shaonan Huang; Qingyan Qiu; Yunting Fang

doi:10.1016/j.envpol.2022.120376

Isotopic imprints of aerosol ammonium over the north China plain

Environ Pollut. 2022 Dec 15:315:120376. doi: 10.1016/j.envpol.2022.120376. Epub 2022 Oct 10.

Authors

Affiliations

¹ CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning, 110016, China; College of Natural Resources Management & Tourism, Mwalimu Julius K. Nyerere University of Agriculture & Technology, P.O. Box 976, Musoma, Tanzania.
² CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning, 110016, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
³ Yale-NUIST Center on Atmospheric Environment, International Joint Laboratory on Climate and Environment Change (ILCEC), Nanjing University of Information Science & Technology, Nanjing, 210044, China.
⁴ College of Biological Science and Technology, Central South University of Forestry and Technology, Changsha, Hunan, 410004, China.
⁵ State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China.
⁶ CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning, 110016, China; Key Laboratory of Stable Isotope Techniques and Applications, Shenyang, Liaoning, 110016, China.
⁷ Key Laboratory of Geospatial Technology for the Middle and Lower Yellow River Regions, Ministry of Education, College of Environment and Planning, Henan University, Kaifeng, 475004, China; Henan Key Laboratory of Air Pollution Prevention and Ecological Security (Henan University), Kaifeng, 475004, China.
⁸ Forest Ecology & Stable Isotope Center, College of Forestry, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
⁹ CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning, 110016, China; Key Laboratory of Stable Isotope Techniques and Applications, Shenyang, Liaoning, 110016, China. Electronic address: fangyt@iae.ac.cn.

PMID: 36228846
DOI: 10.1016/j.envpol.2022.120376

Abstract

Atmospheric PM_2.5 poses a variety of health and environmental risks to urban environments. Ammonium is one of the main components of PM_2.5, and its role in PM_2.5 pollution will likely increase in the coming years as NH₃ emissions are still unregulated and rising in many cities worldwide. However, partitioning urban NH₄⁺ sources remains challenging. Although the ¹⁵N natural abundance (δ¹⁵N) analysis is a promising approach for this purpose, it has seldom been applied across multiple cities within a given region. This limits our understanding of the regional patterns and controls of NH₄⁺ sources in urban environments. Here, we collected PM_2.5 samples using an active sampling technique during winter at six cities in the North China Plain to characterize the concentrations, δ¹⁵N and sources of NH₄⁺ in PM_2.5. We found substantial variations in both the concentrations and δ¹⁵N of NH₄⁺ among the sites. The mean NH₄⁺ concentrations across the six cities ranged from 3.6 to 12.1 μg m^-3 on polluted days and from 0.9 to 10.6 μg m^-3 on non-polluted days. The δ¹⁵N ranged from 6.5‰ to 13.9‰ on polluted days and from 8.7‰ to 13.5‰ on non-polluted days. The δ¹⁵N decreased with increasing NH₄⁺ concentrations at all six sites. We found that non-agricultural sources (vehicle exhaust, ammonia slip and urban wastes) contributed 72%-94% and 56%-86% of the NH₄⁺ on polluted and non-polluted days, respectively, and that during polluted days, combustion-related emissions (vehicle exhaust and ammonia slip) were positively associated with the proportion of urban area, population density and number of vehicles, highlighting the importance of local sources of particulate pollution. This study suggests that the analysis of ¹⁵N in aerosol NH₄⁺ is a promising approach for apportioning atmospheric NH₃ sources over a large region, and this approach has potential for mapping rapidly and precisely the sources of NH₃ emissions.

Keywords: (15)N natural abundance; Aerosol NH(4)(+); Fossil fuel combustion; North China Plain; PM(2.5) pollution; Source partition; Urbanization.

MeSH terms

Aerosols / analysis
Air Pollutants* / analysis
Ammonia / analysis
Ammonium Compounds* / analysis
China
Environmental Monitoring
Particulate Matter / analysis
Seasons

Substances

Ammonium Compounds
Air Pollutants
Ammonia
Aerosols
Particulate Matter