scholarly journals Review of “Impact of particle number and mass size distributions of major chemical components on particle mass scattering efficiency in urban Guangzhou of South China” by Tao et al.

2019 ◽  
Author(s):  
Anonymous
Keyword(s):  
South China ◽  
Particle Number ◽  
Particle Mass ◽  
Chemical Components ◽  
Size Distributions ◽  
Scattering Efficiency ◽  
Mass Size ◽  
Major Chemical

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.

Impact of size distributions of major chemical components in fine particles on light extinction in urban Guangzhou

2017 ◽  
Vol 587-588 ◽  
pp. 240-247 ◽  
Author(s):  
Yunjie Xia ◽  
Jun Tao ◽  
Leiming Zhang ◽  
Renjian Zhang ◽  
Shuanglin Li ◽  
...  
Keyword(s):  
Fine Particles ◽  
Light Extinction ◽  
Chemical Components ◽  
Size Distributions ◽  
Major Chemical

scholarly journals Methodology for high-quality mobile measurement with focus on black carbon and particle mass concentrations

2019 ◽  
Vol 12 (9) ◽  
pp. 4697-4712 ◽  
Author(s):  
Honey Dawn C. Alas ◽  
Kay Weinhold ◽  
Francesca Costabile ◽  
Antonio Di Ianni ◽  
Thomas Müller ◽  
...  
Keyword(s):  
Particle Size ◽  
Black Carbon ◽  
Mass Concentration ◽  
Particle Number ◽  
Measurement Data ◽  
Particle Mass ◽  
Size Distributions ◽  
Mobile Measurements ◽  
Mobile Measurement

Abstract. Measurements of air pollutants such as black carbon (BC) and particle mass concentration in general, using mobile platforms equipped with high-time-resolution instruments, have gained popularity over the last decade due to their wide range of applicability. Assuring the quality of mobile measurement, data have become more essential, particularly when the personal exposure to pollutants is related to their spatial distribution. In the following, we suggest a methodology to achieve data from mobile measurements of equivalent black carbon (eBC) and PM2.5 mass concentrations with high data quality. Besides frequent routine quality assurance measures of the instruments, the methodology includes the following steps: (a) measures to ensure the quality of mobile instruments through repeated collocated measurements using identical instrumentation, (b) inclusion of a fixed station along the route containing quality-assured reference instruments, and (c) sufficiently long and frequent intercomparisons between the mobile and reference instruments to correct the particle number and mass size distributions obtained from mobile measurements. The application of the methodology can provide the following results. First, collocated mobile measurements with sets of identical instruments allow identification of undetected malfunctions of the instruments. Second, frequent intercomparisons against the reference instruments will ensure the quality of the mobile measurement data of the eBC mass concentration. Third, the intercomparison data between the mobile optical particle size spectrometer (OPSS) and a reference mobility particle size spectrometer (MPSS) allow for the adjustment of the OPSS particle number size distribution using physically meaningful corrections. Matching the OPSS and MPSS volume particle size distributions is crucial for the determination of PM2.5 mass concentration. Using size-resolved complex refractive indices and time-resolved fine-mode volume correction factors of the fine-particle range, the calculated PM2.5 from the OPSS was within 5 % of the reference instruments (MPSS+APSS). However, due to the nonsphericity and an unknown imaginary part of the complex refractive index of supermicrometer particles, a conversion to a volume equivalent diameter yields high uncertainties of the particle mass concentration greater than PM2.5. The proposed methodology addresses issues regarding the quality of mobile measurements, especially for health impact studies, validation of modeled spatial distribution, and development of air pollution mitigation strategies.

scholarly journals Methodology for High Quality Mobile Measurement with Focus on Black Carbon and Particle Mass Concentrations

2019 ◽  
Author(s):  
Honey Dawn C. Alas ◽  
Kay Weinhold ◽  
Francesca Costabile ◽  
Antonio Di Ianni ◽  
Thomas Müller ◽  
...  
Keyword(s):  
Particle Size ◽  
Black Carbon ◽  
Mass Concentration ◽  
Particle Number ◽  
Measurement Data ◽  
Particle Mass ◽  
Size Distributions ◽  
Mobile Measurements ◽  
Mobile Measurement

Abstract. Measurements of air pollutants such as black carbon (BC) and particle mass concentration in general, using mobile platforms equipped with high time-resolution instruments have gained popularity over the last decade due to its wide range of applicability. Assuring the quality of mobile measurement, data has become more essential particularly, when the personal exposure to pollutants is related to its spatial distribution. In the following, we suggest a methodology to achieve data from mobile measurements of equivalent black carbon (eBC) and PM2.5 mass concentrations with high data quality. Besides frequent routine quality assurance measures of the instruments, the methodology includes the following steps. a) Measures to ensure the quality of mobile instruments through repeated collocated measurements using identical instrumentation, b) inclusion of a fixed station along the route containing quality-assured reference instruments and c) sufficiently long and frequent intercomparisons between the mobile and reference instruments to correct the particle number and mass size distributions obtained from mobile measurements. The application of the methodology can provide following results. First, collocated mobile measurements with sets of identical instruments allow identification of undetected malfunctions of the instruments. Second, frequent intercomparisons against the reference instruments will ensure the quality of the mobile measurement data of the eBC mass concentration. Third, the intercomparison data between the mobile optical particle size spectrometer (OPSS) and a reference mobility particle size spectrometer (MPSS) allows for the adjustment of the OPSS particle number size distribution using physical meaningful corrections. Matching the OPSS and MPSS volume particle size distributions is crucial for the determination of PM2.5 mass concentration. Using size-resolved complex refractive indices and time-resolved fine mode volume correction factors of the fine particle range, the calculated PM2.5 was within 5 % of the reference instruments (MPSS+APSS). However, due to the non-sphericity and an unknown imaginary part of the complex refractive index of supermicrometer particles, a conversion to a volume equivalent diameter yields high uncertainties of the particle mass concentration greater than PM2.5. The proposed methodology addresses issues regarding the quality of mobile measurements, especially for health impact studies, validation of modelled spatial distribution, and development of air pollution mitigation strategies.

Isolation and HPLC Determination of the Chemical Components of Gentianella acuta (Michx.) Hulten

2018 ◽  
Vol 15 (1) ◽  
pp. 21-33
Author(s):  
Ying Wei ◽  
Yongqiao Liu ◽  
Yifan Hele ◽  
Weiwei Sun ◽  
Yang Wang ◽  
...  
Keyword(s):  
Medicinal Plant ◽  
High Speed ◽  
Chemical Constituents ◽  
Folk Medicine ◽  
Gradient Elution ◽  
Chemical Components ◽  
Isolation And Characterization ◽  
Major Chemical ◽  
Main Components ◽  
First Time

Background: Gentianella acuta (Michx.) Hulten is an important type of medicinal plant found in several Chinese provinces. It has been widely used in folk medicine to treat various illnesses. However, there is not enough detailed information about the chemical constituents of this plant or methods for their content determination. Objective: The focus of this work is the isolation and characterization of the major chemical constituents of Gentianella acuta, and developing an analytical method for their determination. Methods: The components of Gentianella acuta were isolated using (1) ethanol extraction and adsorption on macroporous resin. (2) and ethyl acetate extraction and high speed countercurrent chromatography. A HPLC-DAD method was developed using a C18 column and water-acetonitrile as the mobile phase. Based on compound polarities, both isocratic and gradient elution methods were developed. Results: A total of 29 compounds were isolated from this plant, of which 17 compounds were isolated from this genus for the first time. The main components in this plant were found to be xanthones. The HPLC-DAD method was developed and validated for their determination, and found to show good sensitivity and reliability. Conclusion: The results of this work add to the limited body of work available on this important medicinal plant. The findings will be useful for further investigation and development of Gentianella acuta for its valuable medicinal properties.

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