Black Carbon Measurement using Laser Integrating Plate Method

An intensive study to test and validate the Laser Integrating Plate Method (LIPM) of determining absorption coefficient and black carbon mass was carried out. Measurements by LIPM were compared to Smoke Stain Reflectometer measurements and Mie calculations based on accelerator ion beam analysis (IBA) elemental composition measurements. Results show that the value of mass absorption coefficient ? = 10 m²g^{? 1} previously used for mass determination, and widely accepted for black carbon generated by combustion processes, is an inappropriate choice for the type of carbon measured in Sydney. A value of ? = 7 m²g^?1 for soot and ambient aerosol particles was found to be more appropriate.     

Use of proton backscattering to determine the carbon and oxygen content in fine particle samples deposited on PTFE((CF2)n) membrane disk filters

Particulate carbon is routinely measured in the IMPROVE (interagency monitoring of protected visual environments) program by analysis of samples collected on quartz filters. The analysis is performed at Desert Research Institute using the thermal optical reflectance method. Measurements of Si, Al, Ca, Ti, and Fe by X-ray fluorescence at Crocker Nuclear Laboratory are used by IMPROVE to calculate a SOIL parameter by weighting these elements to account for the oxygen and minor elements that are not measured. It is desirable to have alternative methods to measure both carbon and oxygen for data validation purposes.We have tested a method to measure carbon and oxygen concentrations from air samples deposited on PTFE membrane filters using the backscattered proton spectrum. The measurements were performed with a 4.5 MeV proton beam from the cyclotron of the Crocker Nuclear Laboratory during routine IMPROVE measurements of hydrogen by proton elastic scattering analysis. A surface barrier detector at 155° below the plane of the beam was employed in a Cornell geometry setup to measure the proton spectrum. We will discuss a consistent method to estimate the carbon from the PTFE (CF₂)_n membrane substrate that must be subtracted from the measured carbon (filter plus deposit). This method is independent of the number and arrangement of the fibers and the unknown stretching of the substrate. The measured carbon at multiple IMPROVE sites using this new method is generally slightly higher than carbon measured using thermal optical reflectance. The sum of all elements, including the oxygen and carbon determined by proton backscattering, compares somewhat better to gravimetric mass than the same sum using carbon by TOR instead of backscattering.     

Particle Size and Temporal Characteristics of Aerosol Composition near Coal-Fired Electric Power Plants of the Eastern Transvaal

Mine-mouth power plants near the rich coal deposits of the eastern Transvaal supply most of the electricity used in the Republic of South Africa. Their emissions of particulate matter are a significant fraction of the total from all sources in the region and may be partly the cause of visibility degradation, especially in the dry winter months. A study in the vicinity of seven plants was conducted during November and December 1980 in order to demonstrate the usefulness of cascade impactors, time sequence streaker filter samplers, and elemental analysis by particle-induced x-ray emission (PIXE) for characterizing coal combustion aerosol at a nonurban site where relatively few nearby industrial or natural aerosol sources were present. Particle size analysis indicated a distribution of elements on the particles from principally coarse to principally fine (submicrometer diameter) in the sequence Ti, Al, Ca, Fe, Mn, Cr, Zn, K, Si, and S, apparently reflecting a progression of element volatility during combustion. S and Si each contributed nearly half the total fine aerosol mass (< 2 μm aerodynamic diameter) of the elements determined. The identification of a distinct fine-mode Si aerosol is a reflection of the high initial ash content of the fuel and the lower efficiency of the particulate control devices in the submicrometer range. Time sequence analysis of aerosol composition with 2-hr resolution indicated associations of concentrations with wind direction and of elements with each other that permitted distinction of individual plumes in the complex source area.     

A critical review of filter transmittance measurements for aerosol light absorption,and de novo calibration for a decade of monitoring on PTFE membranes

The IMPROVE (Interagency Monitoring of PROtected Visual Environments) network monitors the attenuation of light by PM_2.5 samples (fine particulate matter, D_aero = 2.5 μm) routinely collected on polytetrafluoroethylene (PTFE) filters throughout the United States. The results of this measurement have long been reported as an indicator of absorption, with no rigorous calibration as such. Filter-based absorption measurements more conventionally employ optically thick quartz- or glass-fiber collection media, for which a substantial calibration literature offers algorithms to correct for particle scattering and filter loading effects. PTFE membranes are optically thinner and less homogeneous than the fiber media, but they avoid interference from adsorbed organic gases that is associated with quartz and glass fiber media. IMPROVE's measurement system is a hybrid of integrating sphere and integrating plate that records the light backscattered as well as transmitted by each filter. This article introduces and validates a theory-based model for calibration and data reduction that accounts for particle scattering effects as well as variations in filter optics. Tests based on historical analyses of field blanks and recent reanalyses of archived samples establish that the current system has operated with a stable calibration since 2003.

The newly calibrated IMPROVE absorption values correlate strongly with the refractory carbon fraction reported by thermal-optical analysis as “elemental” (EC). EC is sometimes treated as the only significant light absorber in PM_2.5, but the general decline observed between 2005 and 2014 in IMPROVE EC was not accompanied by a comparable decline in IMPROVE absorption. Absorption also exhibits a distinct association with Fe concentrations, which at IMPROVE sites are attributable mainly to mineral dusts and have generally held steady or risen since 2003. An increased relative contribution by mineral dusts can explain some, but not all, of the observed difference between recent absorption and EC trends.     

Characterization of size-resolved aerosol components using proton induced X-ray emission, inductively coupled plasma optical emission spectrometry and ion chromatography

Size-resolved aerosol monitoring for PM₁₀, PM_2.5, and PM_1.0 was performed to qualify and quantify the elements and ions by using proton induced X-ray emission (PIXE), inductively coupled plasma optical emission spectrometry (ICP-OES), and ion chromatography (IC) analysis. Time-resolved aerosol samplings based on 2-hour and 14-hour intervals were carried out during daytime and nighttime, respectively. Physical and chemical properties of size-resolved aerosols were investigated to characterize air quality in the national park area of Gyeongju, Korea. The PIXE and ICPOES methods made elemental mass of Al, Si, S, K, Ca, Ti, Cr, Fe, Sr, and Pb. And ions of Na⁺, NH₄ ⁺, Ca²⁺, Cl^?, NO ₃ ^? , and SO ₄ ^2? were analyzed by the IC method. The mass concentrations of Si, S, Ti, and Pb determined by PIXE showed relatively good correlation with those determined by ICP-OES. But Fe and Sr had worse correlations with an average R² of 0.4703 and 0.4825, respectively. The PIXE method was a good alternative to measure chemical species of Al, Si, S, K, Ca, Ti, Cr, and Pb for size-resolved aerosols except Fe and Sr in this study. The average relative errors of sizeresolved elements for 2-hour and 14-hour interval collections were 10.1±5.7% (0.1–28.3%) and 9.9±7.7% (1.3–38.4%). Ammonium sulfates (AS), mineral dust (MD), and sea salt (SS) aerosols were reconstructed from the elements determined by PIXE and ICP-OES and ions obtained by IC. The mass concentration of MD was calculated with crustal elements of Al, Si, Ca, Ti, and Fe, which are associated with soil erosion. The average relative error of MD was the lowest value of 0.8% in the PM₁₀ regime and the highest value of 10.0% in the PM_1.0 regime. The average relative errors of AS for PM₁₀, PM_2.5, and PM_1.0 determined by PIXE, ICP-OES, and IC showed relatively lower values of 0.8–5.7%, 1.7–5.9%, and 3.3–8.3%, respectively. The average mass concentrations of AS, MD, and SS of PM₁₀, PM_2.5, and PM_1.0 except submicron SS determined by PIXE were comparable to those determined by ICP-OES and IC within the acceptable relative errors.     

Light Degrading Properties of Size-Fractionated PM 10 Aerosol Samples Collected from an Industrial Area in Brisbane,Australia

Thirty-seven days of PM 10 aerosol samples (particles with aerodynamic diameter <10 w m) were collected in an industrial area in Brisbane during April to June 1999 to study the light extinction efficiencies of urban aerosols in different size ranges. The light scattering coefficient of the air was measured by nephelometry. The light absorption coefficient of the aerosol samples was measured by the integrating plate laser absorption method. Multiple linear regression techniques were used to investigate the relationships between the visibility degrading properties and the chemical composition of the aerosol samples. The results are comparable with those from other visual air quality studies. The absorption of light by fine (PM 2.5 ) aerosols is mainly due to elemental carbon (EC) particles smaller than 0.5 w m. The b 0 ap values of EC particles in different size ranges are 9.08 (< 2.7 w m) and 0.32 (2.7-10 w m)m 2 g -1 , respectively. The absorption of light by coarse (PM 2.5-10 ) aerosols is mainly due to soil ( b 0 ap = 0.17) and organic ( b 0 ap = 1.11) particles. The scattering of light is highly related to the concentration of fine particles in the air (mass scattering efficiency b 0 sp = 1.65) and is mainly due to the fine sulphate ( b 0 sp = 10.9), soil ( b 0 sp = 2.73), and EC ( b 0 sp = 3.89) particles. On average, fine EC (44%), sulphate (20%) and soil (7%) particles, NO 2 (9%), and Rayleigh scattering (19%) were the largest contributors of visibility degradation for the sampling days in this study.     

PIXE and PDMS Methods Applied to Aerosols Analysis

The aim of this study was to apply the PIXE (Particle Induced X-ray Emission) and PDMS (Plasma Desorption Mass Spectrometry) techniques to characterize airborne dust particles containing metals. Aerosols generated at a mineral-sand processing plant were characterized in this study. The aerosol samples were collected at a plant that processes mineral sands to obtain rutile, ilmenite, zircon, and monazite concentrates. A cascade impactor with six stages was used to collect mineral dust particles with aerodynamic diameters in the range of 0.64 to 19.4 _mum. The particles impacted on each stage of the cascade impactor were analyzed by PIXE, which permits the determination of the elemental mass air concentration and the MMAD (Mass Median Aerodynamic Diameter). The chemical compositions of the aerosol samples were identified by PDMS analysis. This study shows that, by using PIXE and PDMS techniques, it is possible to determine the chemical compounds in which the elements are associated in the aerosol particles. Based on the results of the PIXE analysis, the elemental mass concentrations and the MMADs were determined.     

Proton microprobe PIXE-analyses of single aerosol particles

A method for elemental analyses of individual aerosol particles by means of a focused proton beam and the PIXE method is demonstrated. Preliminary tests of the method has been performed successfully and several aspects on the results are discussed.     

FS序列火焰法测定饮用水中铜锌铁锰

建立简便、快速、高效的同时测定生活饮用水中多种金属元素的方法。利用原子吸收光谱仪的FS(快速)序列分析技术,同时测定Cu、Zn、Fe、Mn 4种待测元素。铜、锌、铁、锰的回归方程的相关系数分别为0.9998、0.9981、0.9999、0.9992。用FS序列同时测定多种金属元素方法简单、快速、准确,既减少工作量,又节省样品,值得推广。     

Feasibility of the Detection of Trace Elements in Particulate Matter Using Online High-Resolution Aerosol Mass Spectrometry

The feasibility of using an online thermal-desorption electron-ionization high-resolution aerosol mass spectrometer (HR-AMS) for the detection of particulate trace elements was investigated by analyzing data from Mexico City obtained during the MILAGRO 2006 field campaign. This potential application is of interest due to the real-time data provided by the AMS, its high sensitivity and time resolution, and the widespread availability and use of this instrument. High-resolution mass spectral analysis, isotopic ratios, and ratios of different ions containing the same elements are used to constrain the chemical identity of the measured ions. The detection of Cu, Zn, As, Se, Sn, and Sb is reported. There was no convincing evidence for the detection of other trace elements commonly reported in ambient particulate matter (PM). The elements detected tend to be those with lower melting and boiling points, as expected given the use of a vaporizer at 600°C in this instrument. The detection limit (DL) is estimated at approximately 0.3 ng m^?3 for 5 min of data averaging. Concentration time series obtained from the AMS data were compared to concentration records determined from offline analysis of particle samples from the same times and locations by inductively coupled plasma based techniques (ICP; PM_2.5) and proton-induced X-ray emission (PIXE; PM_1.1 and PM_0.3). The degree of correlation and agreement between the three instruments (AMS, ICP, and PIXE) varied depending on the element. The AMS shows promise for real-time detection of some trace elements, although additional work including laboratory calibrations with different chemical forms of these elements is needed to further develop this technique and to understand the differences with the ambient data from the other techniques. The trace elements peaked in the morning as expected for primary sources, and the many detected plumes suggest the presence of multiple point sources, probably industrial, in Mexico City, which are variable in time and space, in agreement with previous studies.

Copyright 2012 American Association for Aerosol Research     

PIXE analysis of silk

The method of proton-induced X-ray emission (PIXE) was first utilized to analyze the elements in silk. Different kinds of silk from home and the wild were examined. The results show that every silk, besides C, H, O, and N, contains many types of elements such as Si, P. S, Ca, Mn, Fe, Cu, Zn, and Sr and different samples have different relative contents. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 405–408, 1997     

Atomic hydrogenation-induced paramagnetic-ferromagnetic transition in zinc ferrite

A paramagnetic-ferromagnetic transition was observed in normal spinel zinc ferrite (ZnFe₂O₄) during atomic hydrogenation at room temperature. Magnetic measurements showed enhanced ferromagnetic property with increasing hydrogenation time. The hydrogenated ZnFe₂O₄ has normal spinel structure according to X-ray diffraction (XRD) and Raman analyses. Iron hydride was found from the XRD and X-ray absorption fine structure results. No A–B site ions exchange was observed in the x-ray absorption spectra while the atomic distances of Fe–O, Zn–O, Fe–Fe, Zn–Zn and Fe–Zn coordinations were reduced. A hybrid of Fe²⁺ and Fe³⁺ in hydrogenated ZnFe₂O₄ can be further revealed through deconvolution of x-ray absorption near edge structure. The paramagnetic-ferromagnetic transition and enhanced ferromagnetic property were mainly due to the formation of iron hydride and the B-site super-exchange interactions of Fe²⁺ and Fe³⁺.     

Characterization and demonstration of a black carbon aerosol mimic for instrument evaluation

This study describes the characterization of a H₂O-dispersible, highly-absorbing carbonaceous nanomaterial that mimics the morphological and spectroscopic properties of aged black carbon aerosol (BC). When atomized from aqueous suspension, the material forms particles with a collapsed morphology resembling aged soot or BC. The material is >90 percent elemental carbon and has a mass absorption coefficient (MAC) and spectral dependence consistent with BC values published in the literature. The MAC at a wavelength of 532?nm decreased monotonically from 8.5 to 5.8?m² g^?1 for aerosol with mobility diameters between 150?nm to 500?nm. The single scatter albedo (SSA) at wavelengths of 405?nm and 660?nm was a function of both wavelength and mobility diameter and increased from 0.1 to 0.4 with mobility diameters between 150?nm to 400?nm. The Ångström absorption exponent (AAE) between λ?=?405?nm and 780?nm decreased monotonically from 1.4 to 0.6 for aerosol with mobility diameters between 150?nm to 400?nm. We demonstrate that this material can be used for fast, efficient calibration of aerosol photoacoustic spectrometers and for evaluation of spectroscopic-based measurements of aerosol mass concentration using in-situ photoacoustic spectroscopy (PAS) and filter-based light attenuation measurements for up 50?µg m^?3, enabling inter-method and inter-laboratory instrument comparison.

Copyright © 2019 American Association for Aerosol Research     

Aerosol Absorption Measurement using Photoacoustic Spectroscopy: Sensitivity,Calibration, and Uncertainty Developments

Light absorption by aerosols is one of the most uncertain parameters associated with the direct and indirect aerosol effects on climate and is one of the most difficult quantities to measure. This article describes the development of a sensitive method of measuring aerosol absorption at 532 nm with excellent time response (detection limit: 0.08 Mm^?1, 60 second average) using photoacoustic absorption spectroscopy. An accurate calibration method (accuracy of 1–2%) at atmospherically relevant absorption levels and independent validation of the photoacoustic technique is presented. An upper limit to the instrument precision for aerosol absorption measurement is ～6% (2σ, 30 sec) while instrument accuracy is calculated to be ～5%. A standard for aerosol absorption measurement techniques using well characterized absorbing aerosol is also proposed.     

ICP-OES法测定印染废水中多种金属元素

建立了电感耦合等离子体发射光谱(ICP-OES)测定印染废水中Al、Cr、Mn、Fe、V、Ni、Cu、Zn、As、Pb等金属元素的分析方法。样品经微波消解后直接用ICP-OES测定,对影响测定的各种因素进行了较为详细的研究,确定了仪器的最佳工作参数,选择了合适的分析谱线。研究结果表明,10种金属元素的检出限在0.26～58.24μg/L之间;线性关系良好,线性相关系数R2≥0.999 9;精密度良好,RSD<3.1%;回收率为90.48%～108.46%。     

Comparative study of elemental mass size distributions in urban atmospheric aerosol

Elemental mass size distributions in aerosols collected at four different urban sites with gradually increasing overall aerosol mass concentration are presented, compared and discussed in the present paper. The aerosol samples were collected with cascade impactor and stacked filter unit samplers, and were analyzed by particle-induced X-ray emission spectrometry and instrumental neutron activation analysis. Typical coarse-mode elements, i.e., Na, Mg, Al, Si, P, Ca, Ti, Fe, Ga, Sr, Zr, Mo and Ba, exhibited unimodal size distributions at all four urban locations studied, and the mass median aerodynamic diameters were increased with aerosol pollution level. Elements typically related to high-temperature or anthropogenic sources, i.e., S, Cl, K, V, Cr, Mn, Ni, Cu, Zn, Ge, As, Se, Br, Rb and Pb, either had a unimodal size distribution with most or their mass in the fine size fraction or clearly showed a bimodal size distribution at the urban background site. However, significant differences between the size distributions of four sampling sites were noted. There was a clear tendency for the accumulation mode to decrease and for the coarse mode to increase with increasing total aerosol mass concentration. A pronounced resuspension of the soil and roadway dust associated with the fine aerosol particles that were deposited on the ground surface previously, and the condensation process of volatile precursor gases on the already existing aerosol particles can explain the observed tendencies. The elemental mass size distributions derived for the polluted urban environments differ from those typically observed for industrial, combustion or automotive sources. A consequence of the diversity in the size distributions on the PM_2.5 speciation concept is also presented.     

Scattering and absorption coefficients vs. chemical composition of fine atmospheric aerosol particles under regional conditions in Hungary

The light scattering and absorption coefficients of aerosol particles with a dry diameter below 1 μm were recorded in the country air of Hungary. Concentrations of different inorganic and organic ions were measured in parallel to estimate the nature of particles causing light scattering. The sample air was heated gently to maintain a relative humidity of 30% and coarse particles were removed by a multi-jet impactor. The aerosol light scattering coefficient was monitored with an integrating nephelometer, while absorption was measured on the basis of the rate of blackening of a filter. Results gained during two time periods, mostly in the winter months, are presented in this paper. Data show that the winter average light scattering coefficient is 93 Mm⁻¹, while the corresponding figure for light absorption is 8.9 Mm⁻¹. This results in a single-scatter albedo of 0.91. Comparison of the optical data with chemical information indicates that there is a good correlation between light scattering coefficient and sulfate concentration. The relationship is significant, in particular, in the winter half-year. Regression calculations among the measured parameters suggest for summer and winter half-year a sulfate mass scattering efficiency of 6 and 8 m² g⁻¹, respectively. By using a mass absorption efficiency of 10 m² g⁻¹, the average winter absorption coefficient corresponds to an elemental carbon concentration of 0.9 μg m⁻³.     

An intercomparison of aerosol absorption measurements conducted during the SEAC4RS campaign

During the SEAC⁴RS campaign in 2013, inflight measurements of light-absorption by aerosol in biomass burning and agriculture fire plumes were collected along with concomitant measurements of aerosol extinction, scattering, and black carbon mass concentration. Here, we compare three measurements of aerosol absorption coefficients: from a photoacoustic spectrometer (PAS), a particle soot absorption photometer (PSAP), and a continuous light absorption photometer (CLAP). Each of these absorption measurements was collected in three visible spectral regions: red, green, and blue (although the precise wavelength and bandwidth vary with each instrument). The absorption measurements were compared during the plumes, in the boundary layer, and in the free troposphere. The slopes from the comparison ranged from 0.6 to 1.24. For biomass burning plumes, the uncertainty in the absorption measurements translates into a range in single scattering albedos of 0.93–0.94 at a wavelength of 660?nm, 0.94–0.95 at 532?nm and 0.92–0.95 at 405?nm. Overall, the aerosol absorption instruments agreed within their stated accuracies. Comparisons with simultaneous measurements of refractive black carbon mass concentration (collected by a single particle soot photometer), were used to derive the mass absorption coefficients (MAC). For all wavelengths, the MAC was high by greater than a factor of three compared to the expected MAC for black carbon.

© 2018 American Association for Aerosol Research     

男女头发中微量元素的分析比较研究

采用4∶1的硝酸与高氯酸的混酸体系作为消化液进行样品消解,用火焰原子吸收分光光度法(FAAS)测定了6名成年男女头发中微量元素Fe、Mn、Cu、Zn、Ca和Mg的含量,发现被测头发样本中,Mg、Zn的含量普遍偏高,男头发中铁含量高于女的。     

Investigation on the inhibition effect of aspartic acid and Zn2+ ions on carbon steel surface in aqueous solution

A protective film has been formed on the surface of carbon steel in aqueous environment using a synergistic mixture of an environment-friendly inhibitor, aspartic acid, and Zn²⁺. The synergistic effect of aspartic acid (AS) in controlling corrosion of carbon steel has been investigated by gravimetric studies in the presence of Zn²⁺. The formulation consisting of AS and Zn²⁺ has an excellent inhibition efficiency. The results of potentiodynamic polarization revealed that the formulations are of mixed-type inhibitor. Impedance studies of the metal/solution interface indicated that the surface film is highly protective against the corrosion of carbon steel in the aqueous environment. X-ray photoelectron spectroscopic analysis of the protective film showed the presence of the elements iron, nitrogen, oxygen, carbon, and zinc. The spectra of these elements in the surface film showed the presence of oxides/hydroxides of iron(III), Zn(OH)₂, and [Fe(III)/Fe(II)–Zn(II)-AS] complex. Further, surface characterization techniques such as Fourier transform infrared spectroscopy, scanning electron microscopy, and atomic force microscopy are used to ascertain the nature of the protective film formed on the carbon steel surface.