scholarly journals Impact of particle number and mass size distributions of major chemical components on particle mass scattering efficiency in urban Guangzhou of South China

2019 ◽  
Author(s):  
Jun Tao ◽  
Zhisheng Zhang ◽  
Yunfei Wu ◽  
Leiming Zhang ◽  
Zhijun Wu ◽  
...  
Keyword(s):  
South China ◽  
Chemical Species ◽  
Particle Mass ◽  
Urban Site ◽  
Chemical Compositions ◽  
Small Range ◽  
Scattering Efficiency ◽  
Coarse Mode ◽  
Major Chemical ◽  
Mass Concentrations

Abstract. To grasp the key factors affecting particle mass scattering efficiency (MSE), particle mass and number size distribution, bulk PM2.5 and PM10 and their major chemical compositions, and particle scattering coefficient (bsp) under dry condition were measured at an urban site in Guangzhou, south China during 2015–2016. On annual average, 10 ± 2 %, 48 ± 7 % and 42 ± 8 % of PM10 mass were in the condensation, droplet and coarse modes, with mass median aerodynamic diameters (MMADs) of 0.21 ± 0.00, 0.78 ± 0.07 and 4.57 ± 0.42 μm, respectively. The identified chemical species mass concentrations can explain 79 ± 3 %, 82 ± 6 % and 57 ± 6 % of the total particle mass in the condensation, droplet and coarse mode, respectively. Organic matter (OM) and elemental carbon (EC) in the condensation mode, OM, (NH4)2SO4, NH4NO3 and crustal element oxides in the droplet mode, and crustal element oxides, OM and CaSO4 in the coarse mode were the dominant chemical species in their respective modes. The measured bsp can be reconstructed to the level of 91 ± 10 % using Mie theory with input of the estimated chemically-resolved number concentrations of NaCl, NaNO3, Na2SO4, NH4NO3, (NH4)2SO4, K2SO4, CaSO4, Ca(NO3)2, OM, EC, crustal element oxides and unidentified fraction. MSEs of bulk particle and individual chemical species were underestimated by less than 13 % in any season based on the estimated bsp and chemical species mass concentrations. Seasonal average MSEs varied in a small range of 3.5 ± 0.1 to 3.9 ± 0.2 m2 g−1 for fine particles, which was mainly caused by seasonal variations of the mass fractions and MSEs of OM in the droplet mode.

scholarly journals Impact of particle number and mass size distributions of major chemical components on particle mass scattering efficiency in urban Guangzhou in southern China

2019 ◽  
Vol 19 (13) ◽  
pp. 8471-8490 ◽  
Author(s):  
Jun Tao ◽  
Zhisheng Zhang ◽  
Yunfei Wu ◽  
Leiming Zhang ◽  
Zhijun Wu ◽  
...  
Keyword(s):  
Size Distribution ◽  
Southern China ◽  
Chemical Species ◽  
Particle Mass ◽  
Urban Site ◽  
Chemical Compositions ◽  
Scattering Efficiency ◽  
Coarse Mode ◽  
Major Chemical ◽  
Mass Concentrations

Abstract. To grasp the key factors affecting particle mass scattering efficiency (MSE), particle mass and number size distribution, PM2.5 and PM10 and their major chemical compositions, and the particle scattering coefficient (bsp) under dry conditions were measured at an urban site in Guangzhou, southern China, during 2015–2016. On an annual average, 10±2 %, 48±7 % and 42±8 % of PM10 mass were in the condensation, droplet and coarse modes, respectively, with mass mean aerodynamic diameters (MMADs) of 0.78±0.07 in the droplet mode and 4.57±0.42 µm in the coarse mode. The identified chemical species mass concentrations can explain 79±3 %, 82±6 % and 57±6 % of the total particle mass in the condensation, droplet and coarse mode, respectively. Organic matter (OM) and elemental carbon (EC) in the condensation mode, OM, (NH4)2SO4, NH4NO3, and crustal element oxides in the droplet mode, and crustal element oxides, OM, and CaSO4 in the coarse mode, were the dominant chemical species in their respective modes. The measured bsp can be reconstructed to the level of 91±10 % using Mie theory with input of the estimated chemically resolved number concentrations of NaCl, NaNO3, Na2SO4, NH4NO3, (NH4)2SO4, K2SO4, CaSO4, Ca(NO3)2, OM, EC, crustal element oxides and unidentified fraction. MSEs of particle and individual chemical species were underestimated by less than 13 % in any season based on the estimated bsp and chemical species mass concentrations. Seasonal average MSEs varied in the range of 3.5±0.1 to 3.9±0.2 m2 g−1 for fine particles (aerodynamic diameter smaller than 2.1 µm), which was mainly caused by seasonal variations in the mass fractions and MSEs of the dominant chemical species (OM, NH4NO3, (NH4)2SO4) in the droplet mode. MSEs of the dominant chemical species were determined by their lognormal size-distribution parameters, including MMADs and standard deviation (σ) in the droplet mode.

scholarly journals Characteristics of PM2.5 Chemical Compositions and Their Effect on Atmospheric Visibility in Urban Beijing, China during the Heating Season

2018 ◽  
Vol 15 (9) ◽  
pp. 1924 ◽  
Author(s):  
Xing Li ◽  
Shanshan Li ◽  
Qiulin Xiong ◽  
Xingchuan Yang ◽  
Mengxi Qi ◽  
...  
Keyword(s):  
Fine Particles ◽  
Inorganic Ions ◽  
Water Soluble ◽  
Motor Vehicles ◽  
Urban Site ◽  
Chemical Compositions ◽  
Heating Season ◽  
Atmospheric Visibility ◽  
Visibility Impairment ◽  
Mass Concentrations

Beijing, which is the capital of China, suffers from severe Fine Particles (PM2.5) pollution during the heating season. In order to take measures to control the PM2.5 pollution and improve the atmospheric environmental quality, daily PM2.5 samples were collected at an urban site from 15 November to 31 December 2016, characteristics of PM2.5 chemical compositions and their effect on atmospheric visibility were analyzed. It was found that the daily average mass concentrations of PM2.5 ranged from 7.64 to 383.00 μg m−3, with an average concentration of 114.17 μg m−3. On average, the Organic Carbon (OC) and Elemental Carbon (EC) contributed 21.39% and 5.21% to PM2.5, respectively. Secondary inorganic ions (SNA: SO42− + NO3− + NH4+) dominated the Water-Soluble Inorganic Ions (WSIIs) and they accounted for 47.09% of PM2.5. The mass concentrations of NH4+, NO3− and SO42− during the highly polluted period were 8.08, 8.88 and 6.85 times greater, respectively, than during the clean period, which contributed most to the serious PM2.5 pollution through the secondary transformation of NO2, SO2 and NH3. During the highly polluted period, NH4NO3 contributed most to the reconstruction extinction coefficient (b′ext), accounting for 35.7%, followed by (NH4)2SO4 (34.44%) and Organic Matter (OM: 15.24%). The acidity of PM2.5 in Beijing was weakly acid. Acidity of PM2.5 and relatively high humidity could aggravate PM2.5 pollution and visibility impairment by promoting the generation of secondary aerosol. Local motor vehicles contributed the most to NO3−, OC, and visibility impairment in urban Beijing. Other sources of pollution in the area surrounding urban Beijing, including coal burning, agricultural sources, and industrial sources in the Hebei, Shandong, and Henan provinces, released large amounts of SO2, NH3, and NO2. These, which were transformed into SO42−, NH4+, and NO3− during the transmission process, respectively, and had a great impact on atmospheric visibility impairment.

scholarly journals Characteristics of PM<sub>2.5</sub> mass concentrations and chemical species in urban and background areas of China: emerging results from the CARE-China network

2018 ◽  
Author(s):  
Zirui Liu ◽  
Wenkang Gao ◽  
Yangchun Yu ◽  
Bo Hu ◽  
Jinyuan Xin ◽  
...  
Keyword(s):  
Chemical Species ◽  
Central China ◽  
Research Network ◽  
Mitigation Measures ◽  
Chemical Components ◽  
Chemical Compositions ◽  
East Central ◽  
Urban Sites ◽  
Mass Concentrations

Abstract. The Campaign on atmospheric Aerosol REsearch network of China (CARE-China) is a long-term project for the study of the spatiotemporal distributions of physical aerosol characteristics as well as the chemical components and optical properties of aerosols over China. This study presents the first long-term datasets from this project, including three years of observations of online PM2.5 mass concentrations (2012–2014) and one year of observations of PM2.5 compositions (2012–2013) from the CARE-China network. The average PM2.5 concentrations at 20 urban sites is 73.2 μg/m3 (16.8–126.9 μg/m3), which was three times higher than the average value from the 12 background sites (11.2–46.5 μg/m3). The PM2.5 concentrations are generally higher in east-central China than in the other parts of the country due to their relative large particulate matter (PM) emissions and the unfavorable meteorological conditions for pollution dispersion. A distinct seasonal variability of the PM2.5 is observed, with highs in the winter and lows during the summer at urban sites. Inconsistent seasonal trends were observed at the background sites. Bimodal and unimodal diurnal variation patterns were identified at both urban and background sites. The chemical compositions of PM2.5 at six paired urban and background sites located within the most polluted urban agglomerations and cleanest regions of China were analyzed. The major PM2.5 constituents across all the urban sites are organic matter (OM, 26.0 %), SO42− (17.7 %), mineral dust (11.8 %), NO3− (9.8 %), NH4+ (6.6 %), elemental carbon (EC) (6.0 %), Cl− (1.2 %) at 45 % RH and residual matter (20.7 %). Similar chemical compositions of PM2.5 were observed at background sites but were associated with higher fractions of OM (33.2 %) and lower fractions of NO3− (8.6 %) and EC (4.1 %). Significant variations of the chemical species were observed among the sites. At the urban sites, the OM ranged from 12.6 μg/m3 (Lhasa) to 23.3 μg/m3 (Shenyang), the SO42− ranged from 0.8 μg/m3 (Lhasa) to 19.7 μg/m3 (Chongqing), the NO3− ranged from 0.5 μg/m3 (Lhasa) to 11.9 μg/m3 (Shanghai) and the EC ranged from 1.4 μg/m3 (Lhasa) to 7.1 μg/m3 (Guangzhou). The PM2.5 chemical species at the background sites exhibited larger spatial heterogeneities than those at urban sites, suggesting the different contributions from regional anthropogenic or natural emissions and from the long-range transport to background areas. Notable seasonal variations of PM2.5 polluted days were observed, especially for the megacities in east-central China, resulting in frequent heavy pollution episodes occurring during the winter. The evolution of the PM2.5 chemical compositions on polluted days was similar for the urban and nearby background sites, suggesting the significant regional pollution characteristics of the most polluted areas of China. However, the chemical species dominating the evolutions of the heavily polluted events were different in these areas, indicating that unique mitigation measures should be developed for different regions of China. This analysis reveals the spatial and seasonal variabilities of the urban and background aerosol concentrations on a national scale and provides insights into their sources, processes, and lifetimes.

scholarly journals Quantification of aerosol chemical composition using continuous single particle measurements

2011 ◽  
Vol 11 (14) ◽  
pp. 7027-7044 ◽  
Author(s):  
C.-H. Jeong ◽  
M. L. McGuire ◽  
K. J. Godri ◽  
J. G. Slowik ◽  
P. J. G. Rehbein ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Single Particle ◽  
Chemical Species ◽  
Rural Site ◽  
Urban Site ◽  
Particle Analysis ◽  
Single Particle Analysis ◽  
Mass Calibration ◽  
Particle Sizer ◽  
Mass Concentrations

Abstract. Mass concentrations of sulphate, nitrate, ammonium, organic carbon (OC), elemental carbon (EC) were determined from real time single particle data in the size range 0.1–3.0 μm measured by an Aerosol Time-of-Flight Mass Spectrometer (ATOFMS) at urban and rural sites in Canada. To quantify chemical species within individual particles measured by an ATOFMS, ion peak intensity of m/z −97 for sulphate, −62 for nitrate, +18 for ammonium, +43 for OC, and +36 for EC were scaled using the number and size distribution data by an Aerodynamic Particle Sizer (APS) and a Fast Mobility Particle Sizer (FMPS). Hourly quantified chemical species from ATOFMS single-particle analysis were compared with collocated fine particulate matter (aerodynamic diameter < 2.5 μm, PM2.5) chemical composition measurements by an Aerosol Mass Spectrometer (AMS) at a rural site, a Gas-Particle Ion Chromatograph (GPIC) at an urban site, and a Sunset Lab field OCEC analyzer at both sites. The highest correlation was found for nitrate, with correlation coefficients (Pearson r) of 0.89 (ATOFMS vs. GPIC) and 0.85 (ATOFMS vs. AMS). ATOFMS mass calibration factors, determined for the urban site, were used to calculate mass concentrations of the major PM2.5 chemical components at the rural site near the US border in southern Ontario. Mass reconstruction using the ATOFMS mass calibration factors agreed very well with the PM2.5 mass concentrations measured by a Tapered Element Oscillating Microbalance (TEOM, r = 0.86) at the urban site and a light scattering monitor (DustTrak, r = 0.87) at the rural site. In the urban area nitrate was the largest contributor to PM2.5 mass in the winter, while organics and sulphate contributed ~64 % of the summer PM2.5 in the rural area, suggesting a strong influence of regional/trans-boundary pollution. The mass concentrations of five major species in ten size-resolved particle-types and aerosol acidity of each particle-type were determined for the rural site. On a mass basis sulphate and OC rich particle-types (OC-S and OC-S-N) accounted for up to 59 % of the particles characterized and aerosols were weakly acidic in the rural area. This is the first study to estimate hourly quantitative data of sulphate, nitrate, ammonium, OC and EC in ambient particles from scaled ATOFMS single particle analysis; these were closely comparable with collocated high time resolution data of sulphate, nitrate and ammonium detected by AMS and GPIC.

Mass concentrations, seasonal variations, chemical compositions and element sources of PM10 at an urban site in Constantine, northeast Algeria

2019 ◽  
Vol 206 ◽  
pp. 106356 ◽  
Author(s):  
F. Bencharif-Madani ◽  
H. Ali-Khodja ◽  
A. Kemmouche ◽  
A. Terrouche ◽  
K. Lokorai ◽  
...  
Keyword(s):  
Seasonal Variations ◽  
Urban Site ◽  
Chemical Compositions ◽  
Mass Concentrations

scholarly journals A new method to quantify mineral dust and other aerosol species from aircraft platforms using single particle mass spectrometry

2019 ◽  
Author(s):  
Karl D. Froyd ◽  
Daniel M. Murphy ◽  
Charles A. Brock ◽  
Pedro Campuzano-Jost ◽  
Jack E. Dibb ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Biomass Burning ◽  
Single Particle ◽  
Atmospheric Aerosol ◽  
Mineral Dust ◽  
Sea Salt ◽  
Particle Mass ◽  
Coarse Mode ◽  
Sampling Statistics ◽  
Mass Concentrations

Abstract. Single-particle mass spectrometer (SPMS) instruments characterize the composition of individual aerosol particles in real time. Their fundamental ability to differentiate the externally mixed particle types that constitute the atmospheric aerosol population enables a unique perspective into sources and transformation. However, quantitative measurements by SPMS systems are inherently problematic. We introduce a new technique that combines collocated measurements of aerosol composition by SPMS and size-resolved absolute particle concentrations on aircraft platforms. Quantitative number, surface area, volume, and mass concentrations are derived for climate-relevant particle types such as mineral dust, sea salt, and biomass burning smoke. Additionally, relative ion signals are calibrated to derive mass concentrations of internally mixed sulfate and organic material that are distributed across multiple particle types. The NOAA Particle Analysis by Laser Mass Spectrometry (PALMS) instrument measures size-resolved aerosol chemical composition from aircraft. We describe the identification and quantification of nine major atmospheric particle classes, including sulfate/organic/nitrate mixtures, biomass burning, elemental carbon, sea salt, mineral dust, meteoric material, alkali salts, heavy fuel oil combustion, and a remainder class. Classes can be sub-divided as necessary based on chemical heterogeneity, accumulated secondary material during aging, or other atmospheric processing. Concentrations are derived for sizes that encompass the accumulation and coarse size modes. A statistical error analysis indicates that particle class concentrations can be determined within a few minutes for abundances above ~ 10 ng m−3. Rare particle types require longer sampling times. We explore the instrumentation requirements and the limitations of the method for airborne measurements. Reducing the size resolution of the particle data increases time resolution with only a modest increase in uncertainty. The principal limiting factor to fast time response concentration measurements is statistically relevant sampling across the size range of interest, in particular, sizes D  2 μm for coarse mode analysis. We demonstrate the use of a virtual impactor to enhance sampling statistics for the inherently sparse coarse mode. Performance is compared to other airborne and ground-based composition measurements, and examples of atmospheric mineral dust concentrations are given. The wealth of information afforded by composition-resolved size distributions for all major aerosol types represents a new and powerful tool to characterize atmospheric aerosol properties in a quantitative fashion.

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