Atmospheric ammonia in China: Long-term spatiotemporal variation, urban-rural gradient, and influencing factors

Jinyan Dong; Baojie Li; Yan Li; Rui Zhou; Cong Gan; Yongqi Zhao; Rui Liu; Yating Yang; Teng Wang; Hong Liao

doi:10.1016/j.scitotenv.2023.163733

Atmospheric ammonia in China: Long-term spatiotemporal variation, urban-rural gradient, and influencing factors

Sci Total Environ. 2023 Jul 20:883:163733. doi: 10.1016/j.scitotenv.2023.163733. Epub 2023 Apr 26.

Authors

Jinyan Dong¹, Baojie Li², Yan Li¹, Rui Zhou³, Cong Gan¹, Yongqi Zhao¹, Rui Liu¹, Yating Yang¹, Teng Wang⁴, Hong Liao¹

Affiliations

¹ Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, School of Environmental Science and Engineering, Nanjing University of Information Science & Technology, Nanjing 210044, China.
² Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, School of Environmental Science and Engineering, Nanjing University of Information Science & Technology, Nanjing 210044, China. Electronic address: baojieli@nuist.edu.cn.
³ College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China.
⁴ College of Oceanography, Hohai University, Nanjing 210098, China.

PMID: 37116808
DOI: 10.1016/j.scitotenv.2023.163733

Abstract

In recent years, atmospheric ammonia (NH₃) concentrations have increased in China. Ammonia control has become one of the next hot topics in air pollution mitigation with the increasing cost of acid gas emission reduction. In this study, using Infrared Atmospheric Sounding Interferometer (IASI) satellite observations, we analyzed the spatiotemporal distribution, the urban-rural gradient of the vertical column densities (VCDs) of NH₃ and the contribution of influencing factors (meteorology, social, atmospheric acid gases, and NH₃ emissions) in China from 2008 to 2019 using hotspot analysis, circular gradient analysis, geographical and temporal weighted regression, and some other methods. Our results showed that NH₃ VCDs in China have significantly increased (31.88 %) from 2008 to 2019, with the highest occurring in North China Plain. The average NH₃ VCDs in urban areas were significantly higher than those in rural areas, and the urban-rural gap in NH₃ VCDs was widening. The results of circular gradient analysis showed an overall decreasing trend in NH₃ VCDs along the urban-rural gradient. We used a geographically and temporally weighted regression model to analyze the contribution of various influencing factors to NH₃ VCDs: meteorology (30.13 %), social (27.40 %), atmospheric acid gases (23.20 %), and NH₃ emissions (19.28 %) factors. The results showed substantial spatiotemporal differences in the influencing factors. Atmospheric acid gas was the main reason for the increase in NH₃ VCDs from 2008 to 2019. A more thorough understanding of the spatiotemporal distribution, urban-rural variations, and factors influencing NH₃ in China will aid in developing control strategies to reduce PM_2.5.

Keywords: Atmospheric ammonia; GTWR; IASI; Spatiotemporal distribution; Urban-rural gradient.