Yinxiao Zhang

Bio: Yinxiao Zhang is an academic researcher from Zhejiang University. The author has contributed to research in topics: Aerosol & Combustion. The author has an hindex of 8, co-authored 14 publications receiving 248 citations. Previous affiliations of Yinxiao Zhang include Shandong University.

Morphology, composition, and mixing state of primary particles from combustion sources — crop residue, wood, and solid waste

Abstract: Morphology, composition, and mixing state of individual particles emitted from crop residue, wood, and solid waste combustion in a residential stove were analyzed using transmission electron microscopy (TEM). Our study showed that particles from crop residue and apple wood combustion were mainly organic matter (OM) in smoldering phase, whereas soot-OM internally mixed with K in flaming phase. Wild grass combustion in flaming phase released some Cl-rich-OM/soot particles and cardboard combustion released OM and S-rich particles. Interestingly, particles from hardwood (pear wood and bamboo) and softwood (cypress and pine wood) combustion were mainly soot and OM in the flaming phase, respectively. The combustion of foam boxes, rubber tires, and plastic bottles/bags in the flaming phase released large amounts of soot internally mixed with a small amount of OM, whereas the combustion of printed circuit boards and copper-core cables emitted large amounts of OM with Br-rich inclusions. In addition, the printed circuit board combustion released toxic metals containing Pb, Zn, Sn, and Sb. The results are important to document properties of primary particles from combustion sources, which can be used to trace the sources of ambient particles and to know their potential impacts in human health and radiative forcing in the air.

Direct Observations of Fine Primary Particles From Residential Coal Burning: Insights Into Their Morphology, Composition, and Hygroscopicity

Abstract: Emissions of residential coal burning are an important contributor to air pollution in developing countries, but few studies have yet comprehensively characterized the physicochemical properties of individual primary particles from residential coal burning. Fine primary particles emitted from eight types of coal with low, medium, and high maturity were collected in the flaming and burn-out stages in a typical residential stove. Based on morphology and composition of individual particles, they were divided into six types: organic matter (OM), OM-S, soot-OM, S-rich, metal, and mineral particles. Low-maturity coals (e.g., lignite) dominantly emitted soot-OM particles in the flaming stage, the medium-maturity coals (e.g., medium-maturity bituminous coals) emitted abundant OM particles, and high-maturity coals (e.g., anthracite) emitted abundant OM-S particles. We found that carbonaceous particles from coal burning significantly decreased with an increase of coal maturity and that soot particles were mainly formed in the flaming stage of low-maturity coals under higher burning temperatures. We concluded that coal maturity and burning temperature both determine particulate properties in coal emissions. In addition, OM and soot particles from residential coal burning displayed extremely weak hygroscopicity, while inorganic salts within individual particles determined particle hygroscopic growth. Understanding the characteristics of particulate matter emitted from residential coal burning is helpful to trace sources of ambient particles and clarify their possible aging mechanism in air influenced by coal burning emissions. Our results suggest that air quality improvements can benefit substantially from the replacement of lowand medium-maturity coals with high-maturity coals, natural gas, or electricity in rural areas. Plain Language Summary Raw coals have beenwidely used for heating and cooking in developing countries such as China, India, Mongolia, and Nepal. Due to inefficient burning and no air pollutant control devices, large amounts of air pollutants are emitted from residential coal burning to indoors and ambient air, which have additional deleterious effects on human health and global climate. In addition, recent studies suggest that residential coal burning is a main source of severe haze pollution in North China. We found that the primary organic particles are dominant aerosols in direct emission of most coal burning. However, many fine black carbon and sulfates that are normally considered as vehicular emission and secondary formation in wintertime hazes, respectively, are also found. Our study provides one database to understand what nature properties of primary aerosol particles emitted from various residential coal burning. We call that air quality improvements can benefit substantially from the replacements of lowand medium-maturity coals with high-maturity coals, natural gas, or electricity in rural areas.

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

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

Chemistry of Atmospheric Fine Particles During the COVID-19 Pandemic in a Megacity of Eastern China

Abstract: Air pollution in megacities represents one of the greatest environmental challenges Our observed results show that the dramatic NOx decrease (77%) led to significant O3 increases (a factor of 2) during the COVID-19 lockdown in megacity Hangzhou, China Model simulations further demonstrate large increases of daytime OH and HO2 radicals and nighttime NO3 radical, which can promote the gas-phase reaction and nocturnal multiphase chemistry Therefore, enhanced NO3− and SO42− formation was observed during the COVID-19 lockdown because of the enhanced oxidizing capacity The PM2 5 decrease was only partially offset by enhanced aerosol formation with its reduction reaching 50% In particular, NO3− decreased largely by 68% PM2 5 chemical analysis reveals that vehicular emissions mainly contributed to PM2 5 under normal conditions in Hangzhou Whereas, stationary sources dominated the residual PM2 5 during the COVID-19 lockdown This study provides evidence that large reductions in vehicular emissions can effectively mitigate air pollution in megacities © 2020 The Authors

Light Absorption by Organic Carbon From Wood Combustion

Abstract: Abstract. Carbonaceous aerosols affect the radiative balance of the Earth by absorbing and scattering light. While black carbon (BC) is highly absorbing, some organic carbon (OC) also has significant absorption, especially at near-ultraviolet and blue wavelengths. To the extent that OC absorbs visible light, it may be a non-negligible contributor to positive direct aerosol radiative forcing. Quantification of that absorption is necessary so that radiative-transfer models can evaluate the net radiative effect of OC. In this work, we examine absorption by primary OC emitted from solid fuel pyrolysis. We provide absorption spectra of this material, which can be related to the imaginary refractive index. This material has polar character but is not fully water-soluble: more than 92% was extractable by methanol or acetone, compared with 73% for water and 52% for hexane. Water-soluble OC contributes to light absorption at both ultraviolet and visible wavelengths. However, a larger portion of the absorption comes from OC that is extractable only by methanol. Absorption spectra of water-soluble OC are similar to literature reports. We compare spectra for material generated with different wood type, wood size and pyrolysis temperature. Higher wood temperature is the main factor creating OC with higher absorption; changing wood temperature from a devolatilizing state of 210 °C to a near-flaming state of 360 °C causes about a factor of four increase in mass-normalized absorption at visible wavelengths. A clear-sky radiative transfer model suggests that, despite the absorption, both high-temperature and low-temperature OC result in negative top-of-atmosphere radiative forcing over a surface with an albedo of 0.19 and positive radiative forcing over bright surfaces. Unless absorption by real ambient aerosol is higher than that measured here, it probably affects global average clear-sky forcing very little, but could be important in energy balances over bright surfaces.

Fractal Dimensions and Mixing Structures of Soot Particles during Atmospheric Processing

Abstract: Soot particles strongly absorb sunlight and hence act as a short-lived warming agent. Atmospheric aging of soot particles changes their morphology and mixing state and consequently alters their optical properties. Here we collected soot particles at tunnel, urban, mountaintop, and background sites in the North China Plain and analyzed their mixing structures and morphology using transmission electron microscopy. Soot particles were further classified into three types: bare-like, partly coated, and embedded. Bare-like soot particles were dominant at the tunnel site, while most soot particles were of the partly coated or embedded type at other sites. Fractal dimensions (Df) of different types of soot particles ranged from 1.80 to 2.16 and increased in the following order: bare-like < partly coated < embedded. Moreover, their average Df changed from 1.8 to 2.0 from the tunnel to the background site. We conclude that the Df can characterize the shape of soot aggregates reasonably well, and its variation refle...