Investigation of sources and formation mechanisms of fine particles and organic aerosols in cold season in Fenhe Plain, China

Abstract. Nitrate aerosol composes a significant fraction of fine particles and plays a key role in regional air quality and climate. To obtain a holistic understanding of the nitrate pollution and its formation mechanisms over the North China Plain (NCP) – the most industrialized and polluted region in northern China, intensive field observations were conducted at three sites during summertime in 2014–2015. The measurement sites include the downtown and downwind of Ji'nan, the capital city of Shandong Province, as well as the peak of NCP – Mt. Tai (1534 m a.s.l.), and hence cover representative urban, rural and remote areas of the region. Elevated nitrate concentrations were observed at all three sites despite distinct temporal and spatial variations. The nitrate / PM2.5 and nitrate / sulfate ratios have significantly increased in Ji'nan (2005–2015) and at Mt. Tai (from 2007 to 2014), indicating the worsening situation of regional nitrate pollution. A multi-phase chemical box model (RACM/CAPRAM) was deployed and constrained by observations to elucidate the nitrate formation mechanisms. The principal formation route is the partitioning of gaseous HNO3 to aerosol phase at daytime, whilst the nocturnal nitrate formation is dominated by the heterogeneous hydrolysis of N2O5. The daytime nitrate production in the NCP region is mainly limited by the availability of NO2 and to a lesser extent O3 and NH3, and the nighttime formation is controlled by both NO2 and O3. NH3 prompts significantly the nitrate formation at daytime but plays a slightly negative role in the nighttime. Our analyses suggest that controlling NOx and O3 is an efficient way at the moment to mitigate nitrate pollution in the NCP region, where NH3 is usually in excess in summer. This study provides observational evidence of rising trend of nitrate aerosol as well as scientific support for formulating effective control strategies for regional haze in China.

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A comparison of atmospheric composition using the Carbon Bond and Regional Atmospheric Chemistry Mechanisms

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-13-6923-2013 ◽

2013 ◽

Vol 13 (3) ◽

pp. 6923-6969 ◽

Cited By ~ 2

Author(s):

G. Sarwar ◽

J. Godowitch ◽

B. Henderson ◽

K. Fahey ◽

G. Pouliot ◽

...

Keyword(s):

Hydrogen Peroxide ◽

Atmospheric Chemistry ◽

Production Efficiency ◽

Fine Particles ◽

Secondary Organic Aerosols ◽

Organic Aerosols ◽

Ozone Production ◽

Atmospheric Composition ◽

Organic Nitrate ◽

Carbon Bond

Abstract. We incorporate the recently developed Regional Atmospheric Chemistry Mechanism (version 2, RACM2) into the Community Multiscale Air Quality modeling system for comparison with the existing 2005 Carbon Bond mechanism with updated toluene chemistry (CB05TU). Compared to CB05TU, RACM2 enhances the domain-wide monthly mean hydroxyl radical concentrations by 46% and nitric acid by 26%. However, it reduces hydrogen peroxide by 2%, peroxyacetic acid by 94%, methyl hydrogen peroxide by 19%, peroxyacetyl nitrate by 40%, and organic nitrate by 41%. RACM2 predictions generally agree better with the observed data than the CB05TU predictions. RACM2 enhances ozone for all ambient levels leading to higher bias at low (< 60 ppbv) concentrations but improved performance at high (>70 ppbv) concentrations. The RACM2 ozone predictions are also supported by increased ozone production efficiency that agrees better with observations. Compared to CB05TU, RACM2 enhances the domain-wide monthly mean sulfate by 10%, nitrate by 6%, ammonium by 10%, anthropogenic secondary organic aerosols by 42%, biogenic secondary organic aerosols by 5%, and in-cloud secondary organic aerosols by 7%. Increased inorganic and organic aerosols with RACM2 agree better with observed data. While RACM2 enhances ozone and secondary aerosols by relatively large margins, control strategies developed for ozone or fine particles using the two mechanisms do not differ appreciably.

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Source apportionment of fine organic aerosols in Beijing

Atmospheric Chemistry and Physics ◽

10.5194/acp-9-8573-2009 ◽

2009 ◽

Vol 9 (21) ◽

pp. 8573-8585 ◽

Cited By ~ 75

Author(s):

Q. Wang ◽

M. Shao ◽

Y. Zhang ◽

Y. Wei ◽

M. Hu ◽

...

Keyword(s):

Organic Matter ◽

Particulate Organic Matter ◽

Biomass Burning ◽

Fine Particles ◽

Organic Aerosols ◽

Gas Chromatography Mass Spectrometry ◽

Chemical Compositions ◽

Vehicle Exhaust ◽

Coal Burning ◽

Alkanoic Acids

Abstract. Fine particles (PM2.5, i.e., particles with an aerodynamic diameter of ≤2.5 μm) were collected from the air in August 2005, August–September 2006, and January–February 2007, in Beijing, China. The chemical compositions of particulate organic matter in the ambient samples were quantified by gas chromatography/mass spectrometry. The dominant compounds identified in summertime were n-alkanoic acids, followed by dicarboxylic acids and sugars, while sugars became the most abundant species in winter, followed by polycyclic aromatic hydrocarbons, n-alkanes, and n-alkanoic acids. The contributions of seven emission sources (i.e., gasoline/diesel vehicles, coal burning, wood/straw burning, cooking, and vegetative detritus) to particulate organic matter in PM2.5 were estimated using a chemical mass balance receptor model. The model results present the seasonal trends of source contributions to organic aerosols. Biomass burning (straw and wood) had the highest contribution in winter, followed by coal burning, vehicle exhaust, and cooking. The contribution of cooking was the highest in summer, followed by vehicle exhaust and biomass burning, while coal smoke showed only a minor contribution to ambient organic carbon.

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Summertime and wintertime atmospheric processes of secondary aerosol in Beijing

10.5194/acp-2019-910 ◽

2019 ◽

Author(s):

Jing Duan ◽

Ru-Jin Huang ◽

Yongjie Li ◽

Qi Chen ◽

Yan Zheng ◽

...

Keyword(s):

Particulate Matter ◽

Seasonal Variations ◽

Chemical Speciation ◽

Fine Particles ◽

Large Fraction ◽

Formation Mechanisms ◽

Urban Air ◽

Aerosol Formation ◽

Secondary Aerosol ◽

Atmospheric Processes

Abstract. Secondary aerosol constitutes a large fraction of fine particles in urban air of China. However, its formation mechanisms and atmospheric processes remain largely uncertain despite considerable studies in recent years. To elucidate the seasonal variations of fine particles composition and secondary aerosol formation, an Aerodyne quadrupole aerosol chemical speciation monitor (Q-ACSM) combined with other online instruments were used to characterize the submicron particulate matter (diameter

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Understanding of formation mechanisms of fine particles formed during rapid pyrolysis of biomass

Fuel ◽

10.1016/j.fuel.2017.12.036 ◽

2018 ◽

Vol 216 ◽

pp. 538-547 ◽

Cited By ~ 4

Author(s):

Qinghua Chang ◽

Rui Gao ◽

Hongjun Li ◽

Guangsuo Yu ◽

Xia Liu ◽

...

Keyword(s):

Fine Particles ◽

Formation Mechanisms ◽

Pyrolysis Of Biomass ◽

Rapid Pyrolysis

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Determination of Dicarboxylic Acids and Levoglucosan in Fine Particles in the Kanto Plain, Japan, for Source Apportionment of Organic Aerosols

Aerosol and Air Quality Research ◽

10.4209/aaqr.2009.11.0075 ◽

2010 ◽

Vol 10 (3) ◽

pp. 282-291 ◽

Cited By ~ 23

Author(s):

Kimiyo Kumagai ◽

Akihiro Iijima ◽

Misato Shimoda ◽

Yoshinori Saitoh ◽

Kunihisa Kozawa ◽

...

Keyword(s):

Source Apportionment ◽

Fine Particles ◽

Organic Aerosols ◽

Dicarboxylic Acids

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Exfoliation Resistance, Microstructure, and Oxide Formation Mechanisms of the White Oxide Layer on CP Ti and Ti–Nb–Ta–Zr Alloys

Materials ◽

10.3390/ma14216599 ◽

2021 ◽

Vol 14 (21) ◽

pp. 6599

Author(s):

Eri Miura-Fujiwara ◽

Soichiro Yamada ◽

Keisuke Mizushima ◽

Masahiko Nishijima ◽

Yoshimi Watanabe ◽

...

Keyword(s):

Oxide Layer ◽

Fine Particles ◽

Interfacial Microstructure ◽

Formation Mechanisms ◽

Oxide Formation ◽

Electron Microscopic ◽

Cross Sectional ◽

Transmission Electron ◽

Frictional Coefficients ◽

Cp Ti

We found that specific biomedical Ti and its alloys, such as CP Ti, Ti–29Nb–13Ta–4.6Zr, and Ti–36Nb–2Ta–3Zr–0.3O, form a bright white oxide layer after a particular oxidation heat treatment. In this paper, the interfacial microstructure of the oxide layer on Ti–29Nb–13Ta–4.6Zr and the exfoliation resistance of commercially pure (CP) Ti, Ti–29Nb–13Ta–4.6Zr, and Ti–36Nb–2Ta–3Zr–0.3O were investigated. The alloys investigated were oxidized at 1273 or 1323 K for 0.3–3.6 ks in an air furnace. The exfoliation stress of the oxide layer was high in Ti–29Nb–13Ta–4.6Zr and Ti–36Nb–2Ta–3Zr–0.3O, and the maximum exfoliation stress was as high as 70 MPa, which is almost the same as the stress exhibited by epoxy adhesives, whereas the exfoliation stress of the oxide layer on CP Ti was less than 7 MPa, regardless of duration time. The nanoindentation hardness and frictional coefficients of the oxide layer on Ti–29Nb–13Ta–4.6Zr suggested that the oxide layer was hard and robust enough for artificial tooth coating. The cross-sectional transmission electron microscopic observations of the microstructure of oxidized Ti–29Nb–13Ta–4.6Zr revealed that a continuous oxide layer formed on the surface of the alloys. The Au marker method revealed that both in- and out-diffusion occur during oxidation in Ti–29Nb–13Ta–4.6Zr and Ti–36Nb–2Ta–3Zr–0.3O, whereas only out-diffusion governs oxidation in CP Ti. The obtained results indicate that the high exfoliation resistance of the oxide layer on Ti–29Nb–13Ta–4.6Zr and Ti-36Nb-2Ta-3Zr-0.3O are attributed to their dense microstructures composing of fine particles, and a composition-graded interfacial microstructure. On the basis of the results of our microstructural observations, the oxide formation mechanism of the Ti–Nb–Ta–Zr alloy is discussed.

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Q-type asteroids: Possibility of non-fresh weathered surfaces

Publications of the Astronomical Society of Japan ◽

10.1093/pasj/psz088 ◽

2019 ◽

Vol 71 (5) ◽

Cited By ~ 1

Author(s):

Sunao Hasegawa ◽

Takahiro Hiroi ◽

Katsuhito Ohtsuka ◽

Masateru Ishiguro ◽

Daisuke Kuroda ◽

...

Keyword(s):

Surface State ◽

Laboratory Experiments ◽

Fine Particles ◽

Ordinary Chondrite ◽

Formation Mechanisms ◽

Space Weathering ◽

Ordinary Chondrites ◽

New Hypothesis

Abstract Itokawa particles, which are samples recovered from the S-complex asteroid 25143 Itokawa by the Hayabusa spacecraft, demonstrate that S-complex asteroids are parent bodies of ordinary chondrite meteorites. Furthermore, they clarify that the space-weathering age of the Itokawa surface is of the order of several thousand years. Traditionally, Q-type asteroids have been considered fresh-surfaced. However, as the space-weathering timescale is approximately three orders of magnitude lesser than the conventionally considered age, the previously proposed formation mechanisms of Q-type asteroids cannot sufficiently explain the surface refreshening. In this study, we propose a new hypothesis on the surface state of Q-type asteroids: Q-type asteroids have a non-fresh weathered surface with a paucity of fine particles. For verifying this hypothesis, laboratory experiments on the space weathering of ordinary chondrites are performed. Based on the results of these experiments, we found that large (more than $100\, \mu \mathrm{m}$) ordinary chondritic particles with space weathering exhibit spectra consistent with Q-type asteroids.

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