Characteristics and source apportionment of fine haze aerosol in Beijing during the winter of 2013

Abstract

For PM 2.5 filter samples collected daily at the Chinese Research Academy of Environmental Sciences (Beijing, China) from December of 2013 to February of 2014 (the winter period), chemical characteristics and sources were investigated with an emphasis on haze events in different alert levels. During the 3 months, the average PM 2.5 concentration was 89 µg m −3 , exceeding the Chinese national standard of 75 µg m −3 in 24 h. The maximum PM 2.5 concentration was 307 µg m −3 , which characterizes developedtype pollution (PM 2.5 / PM 10 >0.5) in the World Health Organization criteria. PM 2.5 was dominated by SO 2− 4 , NO − 3 , and pseudo-carbonaceous compounds with obvious differences in concentrations and proportions between non-haze and haze episodes. The non-negative matrix factorization (NMF) analysis provided reasonable PM 2.5 source profiles, by which five sources were identified: soil dust, traffic emission, biomass combustion, industrial emission, and coal combustion accounting for 13, 22, 12, 28, and 25 % of the total, respectively. The dust impact increased with northwesterlies during non-haze periods and decreased under stagnant conditions during haze periods. A blue alert of heavy air pollution was characterized by the greatest contribution from industrial emissions (61 %). During the Chinese Lantern Festival, an orange alert was issued and biomass combustion was found to be the major source owing to firework explosions. Redalert haze was almost equally contributed by local traffic and transported coal combustion emissions from the vicinity of Beijing (approximately 40 % each) that was distinguished by the highest levels of NO − 3 and SO 2− 4 , respectively. This study also reveals that the severity and source of haze are largely dependent on meteorological conditions.

Evaluating the Recent 2+26 Regional Strategy for Air Quality Improvement During Two Orange Air Pollution Alerts in Beijing: variations of PM<sub>2.5</sub> concentrations, source apportionment, and the relative contribution of local emission and regional transport

“…the comparison of the components of PM2.5 during the pollution episode in 2013 and those in 2016, 2017 and 2018, we found that the proportion of sulfate ions decreased significantly while nitrite ions became the dominant component of PM2.5 during the pollution episodes. This result is consistent with findings from some recent studies(Fromme H et al, 2008;Tan J et al, 2016;Shang X et al, 2018). The dramatic decrease in the proportions of SO4 2and NH4 + ions in PM2.5 during the pollution episode in March 2018 suggested a satisfactory effect of long-term pollution control measures, especially the "Coal to Gas" project, and contingent "2+26" regional emission-reduction measures on the reduction of coal combustion in the Beijing-Tianjin-HebeiRegion.…”

“…There are very few compulsory emission-reduction measures for blue and yellow alerts and most emission-reduction measures are suggestive. The characteristics and effects of these emission-reduction measures during alert periods have been massively studied (Zhong, J. et al, 2017;Zhang, Z. et al,2017;Wang, X. et al, 2017;Zeng, W. et al, 2018;Shang, X. et al, 2018). However, previous emission-reduction measures during orange and red alerts were solely conducted in a specific city (e.g., Beijing) while regional emission-reduction measures implemented simultaneously in many adjacent cities have rarely been implemented and evaluated.…”

Significant changes in the chemical compositions and sources of PM2.5 in Wuhan since the city lockdown as COVID-19

“…S8. Biomass burning was an important contributor to PM 2.5 in north China in winter, with the contributions of 7-12% Shang et al, 2018). In the suburban of Wuhan and its surrounding regions, biomass fuels are still adopted for heating and cooking.…”

A method for measuring the normal acoustic energy flux based on radially polarized transducers

“…However, it is still highly susceptible to the effects of structural vibrations themselves. MEMS vector hydrophone is a new type of hydrophone using microelectromechanical system, and some scholars have proposed that the design of MEMS vector hydrophone that can be rigidly fixed is based on the premise of reducing the acceleration sensitivity, so it is not suitable for acoustic energy flux measurement on the surface of the structure [2] . At present, there have been no reports of measurement techniques for measuring the normal acoustic energy flux on the surface of structures, and this paper studies an underwater normal acoustic energy flux measurement unit that can be installed on the surface of the structure, which can accurately measure the normal acoustic energy flux on the surface of the structure, providing technical support for the study of the underwater radiated sound field, and also provide a signal source for the active control error sensor.…”