Direct observations of organic aerosols in common wintertime hazes in North China: insights into direct emissions from Chinese residential stoves

Abstract

Abstract. Many studies have focused on the physicochemical properties of aerosol particles in unusually severe haze episodes in North China instead of the more frequent and less severe hazes. Consistent with this lack of attention, the morphology and mixing state of organic matter (OM) particles in the frequent light and moderate (L & M) hazes in winter in the North China Plain (NCP) have not been examined, even though OM dominates these fine particles. In the present work, morphology, mixing state, and size of organic aerosols in the L & M hazes were systematically characterized using transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy, atomic force microscopy, and nanoscale secondary ion mass spectrometer, with the comparisons among an urban site (Jinan, S1), a mountain site (Mt. Tai, S2), and a background island site (Changdao, S3) in the same hazes. Based on their morphologies, the OM particles were divided into six different types: spherical (type 1), near-spherical (type 2), irregular (type 3), domelike (type 4), dispersed-OM (type 5), and OM-coating (type 6). In the three sampling sites, types 1–3 of OM particles were most abundant in the L & M hazes and most of them were internally mixed with non-OM particles. The abundant near-spherical OM particles with higher sphericity and lower aspect ratio indicate that these primary OM particles formed in the cooling process after polluted plumes were emitted from coal combustion and biomass burning. Based on the Si-O-C ratio in OM particles, we estimated that 71 % of type 1–3 OM particles were associated with coal combustion. Our result suggests that coal combustion in residential stoves was a widespread source from urban to rural areas in NCP. Average OM thickness which correlates with the age of the air masses in type 6 particles only slightly increased from S1 to S2 to S3, suggesting that the L & M hazes were usually dry (relative humidity < 60 %) with weak photochemistry and heterogeneous reactions between particles and gases. We conclude that the direct emissions from these coal stoves without any pollution controls in rural areas and in urban outskirts contribute large amounts of primary OM particles to the regional L & M hazes in North China.

Morphology, Composition, and Mixing State of Individual Aerosol Particles in Northeast China during Wintertime

“…Both spherical and irregular OM particles were considered as primary OM particles, they formed in cooling polluted plumes from coal combustion and biomass burning [19]. In contrast, the formation mechanism of OM coating was different from spherical OM and irregular OM, and they were normally considered secondary OM particles as the oxidized productions of volatile organic compounds (VOCs) [20,21].…”

Fabrication of Multifunctional Hybrid Composites Using Fly Ash to Control Environmental Pollutants: A Review

“…FA pollutes the atmosphere and threatens human health if it is discharged directly from power plant chimneys into the atmosphere without treatment [7,8]. This is a significant contributor to China's recent air quality and haze problems [9,10]. However, with developing science and technology, FA from power plants is changing from industrial waste into an industrial raw material [11][12][13].…”

Numerical Investigation of the Diffusion Feature of Aerosol

“…haze-fog) have drawn more and more attention [1,2] . Aerosol is a suspension system that composed of small solid ________________________ particles in the air, which is an important source of material to form fog-haze days [3,4] .…”

“…Large plenty of researches have been conducted for the purpose of understanding the size distribution and components [7,8] , optical characteristics [9,10] , and physicochemical properties of aerosol particles [2,11] . The transportation and diffusion of aerosol is vital for the prediction of affected area and the exploration of the emission source.…”