| The haze pollution exerting detrimental effects to public health. The haze formation is closely related to the chemical composition of fine particles. Monitoring for submicron particles and the chemical components of it can help us researching on the secondary aerosol formation, evolution process and insighting into the reason of haze. BIV (Beijing and its vicinity) is represent for the regional environmental pollution in North. It is an urgent task to kown the formation reason of haze and make the controlling measure to solve the issue of air pollution fundamentally. In this study, we report the applications of an Aerosol Chemical Speciation Monitor (ACSM) in characterization of chemical composition of fine particles including organics, sulfate, nitrate, ammonium, and chloride, and rapid estimation of primary and secondary organic aerosols in the atmosphere. The ACSM was deployed for real-time measurements of submicron aerosol species in July to September,2012in Beijing and June2013in Xianghe, Hebei (?)scomposition of fine particles between hazy and clean days exhibits significant differences in September,2012in Beijing. While organics comprise the major fraction of PM1, accounting for～70%on average in clean days, secondary inorganic species increases significantly during the haze pollution days, accounting for more than50%of total PM1. Using the results of positive matrix factorization (PMF) of ACSM organic aerosol, a tracer-m/z based method for real-time estimating primary (HOA) and secondary organic aerosol (OOA) in the fall of Beijing is developed. The HOA and OOA can be estimated as:HOA=26.6×(m/z57-0.02×m/z44) and OOA=4.4×m/z44. The total PM1mass correlates well with the extinction coefficient of fine particles (r2=0.91), illustrating the important roles of submicron fine particles in haze formation. In particular, the correlation between extinction coefficient and secondary species is significantly higher primary species, suggesting that the formation and evolution of secondary particles play a more critical role in the formation of haze.(2) During the observation period in July to September,2012in Beijing, we find it that the clean events with PM1<～20μgm-3and the highly polluted episodes with PM1>100μg m-3occur alternatively. In contrast, the polluted events persist a longer time than clean periods, which sometimes lasting over one week. On average, organic matter was the most abundant fraction in submicron aerosol in Beijing, accounting for～39%. The PM1appeared to be bulk neutralized throughout the observation period. From July to September, the concentration zone of NR-PM1mass concentration closer to the direction of decreasing. The percent contributions of organic show a notable decreasing trend to the extent of～40%. (3) The air quality in Xianghe has suffered severe deterioration, which is imminent to improve air quality and pollution. On average, PM1account for～71%of PM2,5and PM1distributed in20-80μgm-3mainly. Significant straw burning events was observed during June,2013, in Xianghe. During the straw burning period, the mass concentration of PM, significantly increased, and during which, the mass fraction of Org in PM1rapidly increased to about47%on average. Affected by straw burning events, the aerosol acidity turns from weak alkaline to weak acid. Positive matrix factorization was performed on ACSM OA mass spectra and identified two primary OA (POA), i.e. BBOA and HOA. and two secondary factors (SOA), i.e. LV-OOA、SV-OOA. The SOA dominates OA during the observation, contributing70%of OA. The effects of meteorology on PM pollution are also explored. Changes in wind speed, different PM1chemical component shows different trends. In particular, the affect of wind speed is greater to primary aerosol than to secondary aerosol. Simultaneously, the high humidity is one of the most important meteorological factors influencing the trends with wind speed changing. During measurements, regional new particle formation events (NPFs) were observed frequently. The chemical component of PM1shows variation... |
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