Impacts of short-term mitigation measures on PM<sub>2.5</sub> and radiative effects: a case study at a regional background site near Beijing, China

Abstract

Measurements at a background site near Beijing showed that pollution controls implemented during the 19th National Congress of the Communist Party of China (NC-CPC) were effective in reducing PM 2.5 . Mass concentrations of PM 2.5 and its major chemical components were 20.6 %-43.1 % lower during the NCCPC-control period compared with a non-control period, and differences were greater on days with stable meteorological conditions. A receptor model showed that PM 2.5 from traffic-related emissions, biomass burning, industrial processes, and mineral dust was 38.5 %-77.8 % lower during the NCCPC-control versus noncontrol period, but differences in PM 2.5 from coal burning were small, and secondary sources were higher during the NCCPC-control period. During one pollution episode in the non-control period, secondary sources dominated, and the WRF-Chem model showed that the Beijing-Tianjin-Hebei (BTH) region contributed 73.6 % of PM 2.5 mass. A second pollution episode was linked to biomass burning, and BTH contributed 46.9 % of PM 2.5 mass. Calculations based on Interagency Monitoring of Protected Visual Environments (IMPROVE) algorithms showed that organic matter was the largest contributor to light extinction during the non-control period whereas NH 4 NO 3 was the main contributor during the NCCPC. The Tropospheric Ultraviolet and Visible radiation model showed that the average direct radiative forcing (DRF) values at the Earth's surface were −14.0 and −19.3 W m −2 during the NCCPC-control and non-control periods, respectively, and the DRF for the individual PM 2.5 components were 22.7 %-46.7 % lower during the NCCPC. The information and dataset from this study will be useful for developing air pollution control strategies in the BTH region and for understanding associated aerosol radiative effects.

Levels and sources of hourly PM2.5-related elements during the control period of the COVID-19 pandemic at a rural site between Beijing and Tianjin

“…The PMF model is a widely used receptor model to resolve pollution sources and quantify the source contributions to the particulate matter (Gao et al, 2016;Wang et al, 2019;Zíková et al, 2016). The US EPA PMF5.0 model was employed to quantify the mass contributions and the source profiles of the elements in PM 2.5 in this study (Liu et al, 2018).…”

“…Cu can generate blue flames and is used as a catalyzer (Kong et al, 2015). Pb as an oxidant (Pb 3 O 4 ) can help to achieve a steady and reproducible burning rate (Kong et al, 2015;J. Liu et al, 2019).…”

“…Factor 1 was identified as fireworks burning, because it has high loadings of K, Cu, Ba and Pb and these elements are reliable tracers of fireworks burning (Kong et al, 2015;J. Liu et al, 2019).…”

“…However, the variations and contributions of emission sources during this period are still rarely reported (Li et al, 2020;Zheng et al, 2020), in particular for rural areas. Trace elements can act as markers for specific source categories of PM 2.5 (Cui et al, 2019;Y. Liu et al, 2019).…”

Measurement report: Evaluation of sources and mixing state of black carbon aerosol under the background of emission reduction in the North China Plain: implications for radiative effect

“…It is bordered by Beijing in the northwest (~45 km) and Tianjin in the southeast (~79 km). This place is considered to be a regional observation site which suffers from frequent pollution plumes (e.g., urban, rural, or mixed origins) from surrounding areas (Wang et al, 2019a). Intensive measurements were conducted in winter from 1 December 2017 to 31 January 2018.…”