23 Dec 2022
23 Dec 2022
Status: this preprint is currently under review for the journal ACP.

Vehicular ammonia emissions: An underappreciated emission source in densely-populated areas

Yifan Wen1, Shaojun Zhang1,2,3, Ye Wu1,2,3, and Jiming Hao1,2,3 Yifan Wen et al.
  • 1School of Environment, State Key Joint Laboratory of Environment Simulation and Pollution Control, Tsinghua University, Beijing, 100084, China
  • 2State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, Beijing, 100084, China
  • 3Beijing Laboratory of Environmental Frontier Technologies, School of Environment, Tsinghua University, Beijing 100084, China

Abstract. On-road ammonia (NH3) emissions play a significant role in fine particulate matter (PM2.5) formation in urban areas, posing severer risks for human health. Limited studies have depicted the spatial and temporal variations of on-road NH3 emissions, in particular lacking detailed quantification of their contributions within densely-populated areas. In this study, we established a comprehensive vehicular NH3 emission model and compiled a gridded on-road NH3 emission inventory with high spatial (3 km × 3 km), and temporal (monthly) resolutions for mainland China. China’s annual vehicular NH3 emissions are estimated to increase from 32.8 kt to 87.1 kt during the period of 2000–2019. Vehicular NH3 emissions are significantly concentrated in densely-populated areas where agricultural emissions have relatively lower intensity. It is found that vehicular NH3 emissions could exceed agricultural emissions in the grids containing 23.0 % of the Chinese population in 2019 (approximately 326.6 million people), and this ratio is up to 29.4 % in winter. For extreme populous megacities such as Beijing and Shanghai, vehicular NH3 emissions exceed agricultural emissions where 69.2 % and 72.0 % of population resides, respectively. Thus, the significant role of on-road NH3 emissions in populated areas may have been underappreciated. This study gave a better insight into the absolute value and relative importance of on-road NH3 emissions in different regions, seasons and population densities in China, which is important in terms of the air quality implications.

Yifan Wen et al.

Status: open (until 03 Feb 2023)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2022-828', Anonymous Referee #1, 30 Dec 2022 reply
    • AC1: 'Reply on RC1', Shaojun Zhang, 15 Jan 2023 reply
  • RC2: 'Comment on acp-2022-828', Anonymous Referee #2, 02 Jan 2023 reply
    • AC2: 'Reply on RC2', Shaojun Zhang, 15 Jan 2023 reply
  • RC3: 'Comment on acp-2022-828', Anonymous Referee #3, 16 Jan 2023 reply
    • AC3: 'Reply on RC3', Shaojun Zhang, 17 Jan 2023 reply

Yifan Wen et al.


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Short summary
This study established a high-resolution vehicular NH3 emission inventory for mainland China to quantify the absolute value and relative importance of on-road NH3 emissions in different regions, seasons and population density. Our results indicate that the significant role of on-road NH3 emissions in populated urban areas may be underappreciated previously, suggesting the control of vehicular NH3 emission can be a feasible and cost-effective way for mitigating haze pollution in urban areas.