Nitrogen isotopic characteristics of aerosol ammonium in a Chinese megacity indicate the reduction from vehicle emissions during the lockdown period.
Sci Total Environ
; 922: 171265, 2024 Apr 20.
Article
in En
| MEDLINE
| ID: mdl-38417516
ABSTRACT
The role of agricultural versus vehicle emissions in urban atmospheric ammonia (NH3) remains unclear. The lockdown due to the outbreak of COVID-19 provided an opportunity to assess the role of source emissions on urban NH3. Concentrations and δ15N of aerosol ammonium (NH4+) were measured before (autumn in 2017) and during the lockdown (summer, autumn, and winter in 2020), and source contributions were quantified using SIAR. Despite the insignificant decrease in NH4+ concentrations, significantly lower δ15N-NH4+ was found in 2020 (0.6 ± 1.0 in PM2.5 and 1.4 ± 2.1 in PM10) than in 2017 (15.2 ± 6.7 in PM2.5), which indicates the NH3 from vehicle emissions has decreased byâ¼50% during the lockdown while other source emissions are less affected. Moreover, a reversed seasonal pattern of δ15N-NH4+ during the lockdown in Changsha has been revealed compared to previous urban studies, which can be explained by the dominant effect of non-fossil fuel emissions due to the reductions of vehicle emissions during the lockdown period. Our results highlight the effects of lockdown on aerosol δ15N-NH4+ and the importance of vehicle emissions to urban atmospheric NH3, providing conclusive evidence that reducing vehicle NH3 emissions could be an effective strategy to reduce PM2.5 in Chinese megacities.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Air Pollutants
/
Ammonium Compounds
Country/Region as subject:
Asia
Language:
En
Journal:
Sci Total Environ
Year:
2024
Document type:
Article
Affiliation country:
China