scholarly journals A review of current knowledge concerning PM<sub>2. 5</sub> chemical composition, aerosol optical properties and their relationships across China

2017 ◽  
Vol 17 (15) ◽  
pp. 9485-9518 ◽  
Author(s):  
Jun Tao ◽  
Leiming Zhang ◽  
Junji Cao ◽  
Renjian Zhang
Keyword(s):  
Optical Properties ◽  
Chemical Composition ◽  
Northern China ◽  
Ambient Air ◽  
Water Soluble ◽  
Carbonaceous Aerosols ◽  
Aerosol Optical Properties ◽  
Annual Average ◽  
Inorganic Aerosols ◽  
Coastal Cities

Abstract. To obtain a thorough knowledge of PM2. 5 chemical composition and its impact on aerosol optical properties across China, existing field studies conducted after the year 2000 are reviewed and summarized in terms of geographical, interannual and seasonal distributions. Annual PM2. 5 was up to 6 times the National Ambient Air Quality Standards (NAAQS) in some megacities in northern China. Annual PM2. 5 was higher in northern than southern cities, and higher in inland than coastal cities. In a few cities with data longer than a decade, PM2. 5 showed a slight decrease only in the second half of the past decade, while carbonaceous aerosols decreased, sulfate (SO42−) and ammonium (NH4+) remained at high levels, and nitrate (NO3−) increased. The highest seasonal averages of PM2. 5 and its major chemical components were typically observed in the cold seasons. Annual average contributions of secondary inorganic aerosols to PM2. 5 ranged from 25 to 48 %, and those of carbonaceous aerosols ranged from 23 to 47 %, both with higher contributions in southern regions due to the frequent dust events in northern China. Source apportionment analysis identified secondary inorganic aerosols, coal combustion and traffic emission as the top three source factors contributing to PM2. 5 mass in most Chinese cities, and the sum of these three source factors explained 44 to 82 % of PM2. 5 mass on annual average across China. Biomass emission in most cities, industrial emission in industrial cities, dust emission in northern cities and ship emission in coastal cities are other major source factors, each of which contributed 7–27 % to PM2. 5 mass in applicable cities. The geographical pattern of scattering coefficient (bsp) was similar to that of PM2. 5, and that of aerosol absorption coefficient (bap) was determined by elemental carbon (EC) mass concentration and its coating. bsp in ambient condition of relative humidity (RH)  =  80 % can be amplified by about 1.8 times that under dry conditions. Secondary inorganic aerosols accounted for about 60 % of aerosol extinction coefficient (bext) at RH greater than 70 %. The mass scattering efficiency (MSE) of PM2. 5 ranged from 3.0 to 5.0 m2 g−1 for aerosols produced from anthropogenic emissions and from 0.7 to 1.0 m2 g−1 for natural dust aerosols. The mass absorption efficiency (MAE) of EC ranged from 6.5 to 12.4 m2 g−1 in urban environments, but the MAE of water-soluble organic carbon was only 0.05 to 0.11 m2 g−1. Historical emission control policies in China and their effectiveness were discussed based on available chemically resolved PM2. 5 data, which provides the much needed knowledge for guiding future studies and emissions policies.

scholarly journals A review of current knowledge concerning PM<sub>2.5</sub> chemical composition, aerosol optical properties, and their relationships across China

2017 ◽  
Author(s):  
Jun Tao ◽  
Leiming Zhang ◽  
Junji Cao ◽  
Renjian Zhang
Keyword(s):  
Optical Properties ◽  
Chemical Composition ◽  
Current Knowledge ◽  
Northern China ◽  
Water Soluble ◽  
Chemical Components ◽  
Carbonaceous Aerosols ◽  
Ambient Conditions ◽  
Aerosol Optical Properties ◽  
Inorganic Aerosols

Abstract. To obtain a thorough knowledge of PM2.5 chemical composition and its impact on aerosol optical properties across China, existing field studies conducted after the year of 2000 are reviewed and summarized in terms of geographical, inter-annual, and seasonal distributions. Annual PM2.5 was up to six times of the national air quality standard in some megacities in northern China. Annual PM2.5 was higher in northern than southern cities, and higher in inland than coastal cities. In a few cities with data longer than a decade, PM2.5 showed a slight decrease only in the second half of the past decade, while carbonaceous aerosols decreased, sulfate (SO42−) and ammonium (NH4+) remained at high levels, and nitrate (NO3−) increased. The highest seasonal averages of PM2.5 and its major chemical components were mostly observed in the cold seasons. Annual average contributions of secondary inorganic aerosols to PM2.5 ranged from 25 % to 48 %, and those of carbonaceous aerosols ranged from 23 % to 47 %, both with higher values in southern regions due to the frequent dust events in northern China. The geographical pattern of scattering coefficient (bsp) was similar to that of PM2.5, and that of aerosol absorption coefficient (bap) was determined by elemental carbon (EC) mass concentration and its coating. bsp in ambient condition of RH = 80 % can be amplified about 1.8 times of that under dry condition. Secondary inorganic aerosols accounted for about 60 % of aerosol extinction coefficient (bext) under ambient conditions in megacities with RH higher than 70 %. The mass scattering efficiency (MSE) of PM2.5 ranged from 3.0 to 5.0 m2 g−1 for aerosols produced from anthropogenic emissions and from 0.7 to 1.0 m2 g−1 for natural dust aerosols. The mass absorption efficiency (MAE) of EC ranged from 6.5 to 12.4 m2 g−1 in urban environments, but the MAE of water-soluble organic carbon (WSOC) was only 0.05 to 0.11 m2 g−1. Historical emission control policies in China and their effectiveness were discussed based on available chemically resolved PM2.5 data, which provides the much-needed knowledge for guiding future studies and emission policy making.

scholarly journals Long-term record of aerosol optical properties and chemical composition from a high-altitude site (Manora Peak) in Central Himalaya

2010 ◽  
Vol 10 (3) ◽  
pp. 7435-7467 ◽  
Author(s):  
K. Ram ◽  
M. M. Sarin ◽  
P. Hegde
Keyword(s):  
Optical Properties ◽  
Chemical Composition ◽  
High Altitude ◽  
Water Soluble ◽  
Simultaneous Increase ◽  
Central Himalaya ◽  
Aerosol Optical Properties ◽  
Abundance Pattern ◽  
Post Monsoon

Abstract. This MS reports on a long-term study of aerosol optical properties and chemical composition, conducted during February 2005–July 2008, from a high-altitude site (Manora Peak, ~2000 m a.s.l.) in the central Himalaya. The chemical analyses suggest that, on average, total carbonaceous aerosols (TCA) and water-soluble inorganic species (WSIS) contribute nearly 25% and 10% of the total suspended particulate (TSP) mass, respectively. Both, TSP and aerosol optical depth (AOD) exhibit significant increase during summer months, with simultaneous increase in the abundance of mineral dust under the prevailing south-westerly winds and long-range transport from desert regions (from middle-East and Thar Desert in western India). The temporal variability in the abundance pattern of carbonaceous species (EC, OC) is also significantly pronounced, with lower concentrations occurring during summertime (April–June) and monsoon (July–August) and relatively high during post-monsoon (September–November) and wintertime (December–March). The WSOC/OC ratios (range: 0.32 to 0.83) during summer and post-monsoon suggest significant contribution from secondary organic aerosols. The mass fraction of absorbing EC (elemental carbon) ranges from less than a percent (during summer and monsoon) to as high as 7.6% (during winter) and absorption coefficient (babs, at 678 nm) varied as 0.9–33.9 Mm−1 (1 Mm−1=10−6 m−1). The linear regression analysis between (babs and EC concentration (μgC m−3) yields a slope of 12.2(±2.3) m2 g−1, referred as mass absorption efficiency (σabs) of EC. However, temporal data suggests lower σabs values during winter and higher in summer and post-monsoon. The change in the mixing state of aerosols and/or variability in the emission sources could be a plausible reason for the variability in σabs at this high-altitude site (Manora Peak).

Aerosol optical properties affected by a strong dust storm over central and northern China

2010 ◽  
Vol 27 (3) ◽  
pp. 562-574 ◽  
Author(s):  
Jinyuan Xin ◽  
Wupeng Du ◽  
Yuesi Wang ◽  
Qingxian Gao ◽  
Zhanqing Li ◽  
...  
Keyword(s):  
Optical Properties ◽  
Dust Storm ◽  
Northern China ◽  
Aerosol Optical Properties

scholarly journals Chemical and optical properties of carbonaceous aerosols in Nanjing, eastern China: regionally transported biomass burning contribution

2019 ◽  
Vol 19 (17) ◽  
pp. 11213-11233 ◽  
Author(s):  
Xiaoyan Liu ◽  
Yan-Lin Zhang ◽  
Yiran Peng ◽  
Lulu Xu ◽  
Chunmao Zhu ◽  
...  
Keyword(s):  
Optical Properties ◽  
Organic Carbon ◽  
Solar Energy ◽  
Energy Absorption ◽  
Biomass Burning ◽  
Eastern China ◽  
Water Soluble ◽  
Carbonaceous Aerosols ◽  
Southeastern China ◽  
Brown Carbon

Abstract. Biomass burning can significantly impact the chemical and optical properties of carbonaceous aerosols. Here, the biomass burning impacts were studied during wintertime in a megacity of Nanjing, eastern China. The high abundance of biomass burning tracers such as levoglucosan (lev), mannosan (man), galactosan (gal) and non-sea-salt potassium (nss-K+) was found during the studied period with the concentration ranges of 22.4–1476 ng m−3, 2.1–56.2 ng m−3, 1.4–32.2 ng m−3 and 0.2–3.8 µg m−3, respectively. The significant contribution of biomass burning to water-soluble organic carbon (WSOC; 22.3±9.9 %) and organic carbon (OC; 20.9±9.3 %) was observed in this study. Backward air mass origin analysis, potential emission sensitivity of elemental carbon (EC) and MODIS fire spot information indicated that the elevations of the carbonaceous aerosols were due to the transported biomass-burning aerosols from southeastern China. The characteristic mass ratio maps of lev∕man and lev∕nss-K+ suggested that the biomass fuels were mainly crop residuals. Furthermore, the strong correlation (p < 0.01) between biomass burning tracers (such as lev) and light absorption coefficient (babs) for water-soluble brown carbon (BrC) revealed that biomass burning emissions played a significant role in the light-absorption properties of carbonaceous aerosols. The solar energy absorption due to water-soluble brown carbon and EC was estimated by a calculation based on measured light-absorbing parameters and a simulation based on a radiative transfer model (RRTMG_SW). The solar energy absorption of water-soluble BrC in short wavelengths (300–400 nm) was 0.8±0.4 (0.2–2.3) W m−2 (figures in parentheses represent the variation range of each parameter) from the calculation and 1.2±0.5 (0.3–1.9) W m−2 from the RRTMG_SW model. The absorption capacity of water-soluble BrC accounted for about 20 %–30 % of the total absorption of EC aerosols. The solar energy absorption of water-soluble BrC due to biomass burning was estimated as 0.2±0.1 (0.0–0.9) W m−2, considering the biomass burning contribution to carbonaceous aerosols. Potential source contribution function model simulations showed that the solar energy absorption induced by water-soluble BrC and EC aerosols was mostly due to the regionally transported carbonaceous aerosols from source regions such as southeastern China. Our results illustrate the importance of the absorbing water-soluble brown carbon aerosols in trapping additional solar energy in the low-level atmosphere, heating the surface and inhibiting the energy from escaping the atmosphere.

scholarly journals Aerosol optical properties and their radiative effects in northern China

2007 ◽  
Vol 112 (D22) ◽  
Author(s):  
Zhanqing Li ◽  
Xiangao Xia ◽  
Maureen Cribb ◽  
Wen Mi ◽  
Brent Holben ◽  
...  
Keyword(s):  
Optical Properties ◽  
Northern China ◽  
Radiative Effects ◽  
Aerosol Optical Properties

scholarly journals Long-term record of aerosol optical properties and chemical composition from a high-altitude site (Manora Peak) in Central Himalaya

2010 ◽  
Vol 10 (23) ◽  
pp. 11791-11803 ◽  
Author(s):  
K. Ram ◽  
M. M. Sarin ◽  
P. Hegde
Keyword(s):  
Optical Properties ◽  
Chemical Composition ◽  
High Altitude ◽  
Water Soluble ◽  
Western India ◽  
Central Himalaya ◽  
Gangetic Plain ◽  
Long Term Study ◽  
Inorganic Species

Abstract. A long-term study, conducted from February 2005 to July 2008, involving chemical composition and optical properties of ambient aerosols from a high-altitude site (Manora Peak: 29.4° N, 79.5° E, ~1950 m a.s.l.) in the central Himalaya is reported here. The total suspended particulate (TSP) mass concentration varied from 13 to 272 μg m−3 over a span of 42 months. Aerosol optical depth (AOD) and TSP increase significantly during the summer (April–June) due to increase in the concentration of mineral dust associated with the long-range transport from desert regions (from the middle-East and Thar Desert in western India). The seasonal variability in the carbonaceous species (EC, OC) is also significantly pronounced, with lower concentrations during the summer and monsoon (July–August) and relatively high during the post-monsoon (September–November) and winter (December–March). On average, total carbonaceous aerosols (TCA) and water-soluble inorganic species (WSIS) contribute nearly 25 and 10% of the TSP mass, respectively. The WSOC/OC ratios range from 0.36 to 0.83 (average: 0.55 ± 0.15), compared to lower ratios in the Indo-Gangetic Plain (range: 0.35–0.40), and provide evidence for the enhanced contribution from secondary organic aerosols. The mass fraction of absorbing EC ranged from less than a percent (during the summer) to as high as 7.6% (during the winter) and absorption coefficient (babs, at 678 nm) varied between 0.9 to 33.9 Mm−1 (1 Mm−1=10−6 m−1). A significant linear relationship between babs and EC (μgC m−3) yields a slope of 12.2 (± 2.3) m2 g−1, which is used as a measure of the mass absorption efficiency (σabs) of EC.

scholarly journals Does the POA-SOA split matter for global CCN formation?

2013 ◽  
Vol 13 (4) ◽  
pp. 10561-10601 ◽  
Author(s):  
W. Trivitayanurak ◽  
P. J. Adams
Keyword(s):  
Chemical Composition ◽  
Climate Modeling ◽  
Sea Salt ◽  
Size Distributions ◽  
Carbonaceous Aerosols ◽  
Annual Average ◽  
Model Driven ◽  
Sea Salt Aerosols ◽  
Model Layer

Abstract. A model of carbonaceous aerosols has been implemented into the TwO-Moment Aerosol Sectional (TOMAS) microphysics module in the GEOS-Chem CTM, a model driven by assimilated meteorology. Inclusion of carbonaceous emissions alongside pre-existing treatments of sulfate and sea-salt aerosols increases the number of emitted primary aerosol particles by a factor of 2.5 and raises annual-average global CCN(0.2%) concentrations by a factor of two. Compared to the prior model without carbonaceous aerosols, this development improves the model prediction of CN10 number concentrations significantly from −45 to −7% bias when compared to long-term observations. However, similar to other OC/EC models, the model underpredicts OC and EC mass concentrations by a factor of 2–5 when compared to EMEP observations. Because primary OA and secondary OA affect aerosol number size distributions differently, we assess the sensitivity of CCN production, for a fixed source of OA mass, to the assumed POA-SOA split in the model. For a fixed OA budget, we found that CCN(0.2%) decreases nearly everywhere as the model changes from a world dominated by POA emissions to one dominated by SOA condensation. POA is about twice as effective per unit mass at CCN production compared to SOA. Changing from a 100% POA scenario to a 100% SOA scenario, CCN(0.2%) concentrations in the lowest model layer decrease by about 20%. In any scenario, carbonaceous aerosols contribute significantly to global CCN. The SOA-POA split has a significant effect on global CCN and the microphysical implications of POA emissions versus SOA condensation appear to be at least as important as differences in chemical composition as expressed by the hygroscopicity of OA. These findings stress the need to better understand carbonaceous aerosols loadings, the global SOA budget, microphysical pathways of OA formation (emissions versus condensation) as well as chemical composition to improve climate modeling.

scholarly journals Characteristics of Aerosol during a Severe Haze-Fog Episode in the Yangtze River Delta: Particle Size Distribution, Chemical Composition, and Optical Properties

Atmosphere ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 56 ◽  
Author(s):  
Ankang Liu ◽  
Honglei Wang ◽  
Yi Cui ◽  
Lijuan Shen ◽  
Yan Yin ◽  
...  
Keyword(s):  
Particle Size ◽  
Optical Properties ◽  
Chemical Composition ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Water Soluble ◽  
Air Masses ◽  
Soluble Ions ◽  
Wide Range ◽  
Water Soluble Ions

Particle size distribution, water soluble ions, and black carbon (BC) concentration in a long-term haze-fog episode were measured using a wide-range particle spectrometer (WPS), a monitor for aerosols and gases (MARGA), and an aethalometer (AE33) in Nanjing from 16 to 27 November, 2018. The observation included five processes of clean, mist, mix, haze, and fog. Combined with meteorological elements, the HYSPLIT model, and the IMPROVE model, we analyzed the particle size distribution, chemical composition, and optical properties of aerosols in different processes. The particle number size distribution (PNSD) in five processes differed: It was bimodal in mist and fog and unimodal in clean, mix, and haze. The particle surface area size distribution (PSSD) in different processes showed a bimodal distribution, and the second peak of the mix and fog processes shifted to a larger particle size at 480 nm. The dominant air masses in five processes differed and primarily originated in the northeast direction in the clean process and the southeast direction in the haze process. In the mist, mix, and fog processes local air masses dominated. NO3− was the primary component of water soluble ions, with the lowest proportion of 45.6% in the clean process and the highest proportion of 53.0% in the mix process. The ratio of NH4+ in the different processes was stable at approximately 23%. The ratio of SO42− in the clean process was 26.2%, and the ratio of other processes was approximately 20%. The average concentration of BC in the fog processes was 10,119 ng·m−3, which was 3.55, 1.80, 1.60, and 1.46 times that in the processes of clean, mist, mix, and haze, respectively. In the different processes, BC was primarily based on liquid fuel combustion. NO3−, SO42−, and BC were the main contributors to the atmospheric extinction coefficient and contributed more than 90% in different processes. NO3− contributed 398.43 Mm−1 in the mix process, and SO42− and BC contributed 167.90 Mm−1 and 101.19 Mm−1, respectively, during the fog process.

scholarly journals Relating aerosol absorption due to soot, organic carbon, and dust to emission sources determined from in-situ chemical measurements

2013 ◽  
Vol 13 (18) ◽  
pp. 9337-9350 ◽  
Author(s):  
A. Cazorla ◽  
R. Bahadur ◽  
K. J. Suski ◽  
J. F. Cahill ◽  
D. Chand ◽  
...  
Keyword(s):  
Optical Properties ◽  
Chemical Composition ◽  
Radiative Forcing ◽  
Wavelength Dependence ◽  
Optical Measurements ◽  
Carbonaceous Aerosols ◽  
Angstrom Exponent ◽  
Ångström Exponent ◽  
Ångstrom Exponent

Abstract. Estimating the aerosol contribution to the global or regional radiative forcing can take advantage of the relationship between the spectral aerosol optical properties and the size and chemical composition of aerosol. Long term global optical measurements from observational networks or satellites can be used in such studies. Using in-situ chemical mixing state measurements can help us to constrain the limitations of such estimates. In this study, the Absorption Ångström Exponent (AAE) and the Scattering Ångström Exponent (SAE) derived from 10 operational AERONET sites in California are combined for deducing chemical speciation based on wavelength dependence of the optical properties. In addition, in-situ optical properties and single particle chemical composition measured during three aircraft field campaigns in California between 2010 and 2011 are combined in order to validate the methodology used for the estimates of aerosol chemistry using spectral optical properties. Results from this study indicate a dominance of mixed types in the classification leading to an underestimation of the primary sources, however secondary sources are better classified. The distinction between carbonaceous aerosols from fossil fuel and biomass burning origins is not clear, since their optical properties are similar. On the other hand, knowledge of the aerosol sources in California from chemical studies help to identify other misclassification such as the dust contribution.

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