Aerosol samples

The femperafure of fhe plasma in fhe region of observation is fypically 7000-8000 K, and all molecules confained in fhe aerosol sample are atomized. The majorify of fhe atoms are also... 

In Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), a gaseous, solid (as fine particles), or liquid (as an aerosol) sample is directed into the center of a gaseous plasma. The sample is vaporized, atomized, and partially ionized in the plasma. Atoms and ions are excited and emit light at characteristic wavelengths in the ultraviolet or visible region of the spectrum. The emission line intensities are proportional to the concentration of each element in the sample. A grating spectrometer is used for either simultaneous or sequential multielement analysis. The concentration of each element is determined from measured intensities via calibration with standards. 

A. Srecnath, 0. Ramachandian,. H Vincent. Experimenial invesugaiions into the nature ot airflows near blutf bodies with aspiration, with implications to aerosol sampling. Atmospherie F.nt tronment. 1 11.5), 1997... 

As a simple and efficient particle separation device, cyclone collectors can be used for anything from dust removal in a fluid stream to material collection in the fluid conveying system. However, the cyclone is not suitable or economical for the separation of extremely small particles (say, less than 1 /xm), which frequently occur in industrial processes. It is recommended that the size of particles to be separated in an industrial ventilation cyclone be in the region of around 10 to 100 p.m. However, for the purpose of aerosol sampling, the size of particles to be separated may be much less than 10 jxm. 

Interest in the elemental composition of aerosol particles arises from concerns about health effects and the value of these elements to trace the sources of suspended particles. The following physical analysis methods have been applied for the elemental measurements of aerosol samples. A schematic drawing of an x-ray fluorescence system is presented in Fig. 13.42. 

GLOSSASy OF TERMS COMMONLY USED IN AEROSOL SAMPLING... 

Denmark 1.5 days after the explosion. Air samples collected at Roskilde, Denmark on April 27-28, contained a mean air concentration of 241Am of 5.2 pBq/m3 (0.14 fCi/m3). In May 1986, the mean concentration was 11 pBq/m3 (0.30 fCi/m3) (Aarkrog 1988). Whereas debris from nuclear weapons testing is injected into the stratosphere, debris from Chernobyl was injected into the troposphere. As the mean residence time in the troposphere is 20-40 days, it would appear that the fallout would have decreased to very low levels by the end of 1986. However, from the levels of other radioactive elements, this was not the case. Sequential extraction studies were performed on aerosols collected in Lithuania after dust storms in September 1992 carried radioactive aerosols to the region from contaminated areas of the Ukraine and Belarus. The fraction distribution of241 Am in the aerosol samples was approximately (fraction, percent) organically-bound, 18% oxide-bound, 10% acid-soluble, 36% and residual, 32% (Lujaniene et al. 1999). Very little americium was found in the more readily extractable exchangeable and water soluble and specifically adsorbed fractions. 

The accident at the Three Mile Island nuclear reactor in March 1979 resulted in contamination of the containment and auxiliary buildings. An aerosol sample from the auxiliary building obtained by filtering about 1,4xl09 cm3 of air through a fiber glass filter for 8 days contained an estimated total transuranic actinide radioactivity of 13 Bq (350 pCi), of which 241 Am was the major contributor (Kanapilly et al. 

Kanapilly GM, Stanley JA, Newton GJ, et al. 1983. Characterization of an aerosol sample from the auxiliary building of the Three Mile Island reactor. Health Phys 45(5) 981-989. 

PAHs Measured in Aerosol Samples Collected in the Cities Vienna and Linz (Austria)... 

Aerosol samples can be analyzed without further preparation for organic carbon and for carbon, hydrogen, oxygen, and nitrogen (CHON) by infrared spectroscopy, by photoelectron spectroscopy, and by mass spectrometry. However, organic analysis is... 

TABLE 3-1 Extraction Efficiencies (ef) and Organic Carbon Extraction Efficiencies (ocef) of Various Solvents and Binary Mixtures for Atmospheric Aerosol Samples"... 

With emission source chemical signatures and corresponding aerosol or rainwater sample measurements PLS can be used Co calculate a chemical element mass balance (CEB). Exact emission profiles for the copper smelter and for a power plant located further upwind were not available for calculation of source contributions to Western Washington rainwater composition. This type of calculation Is more difficult for rainwater Chan for aerosol samples due Co atmospheric gas to particle conversion of sulfur and nitrogen species and due Co variations In scavenging efficiencies among species. Gatz (14) has applied Che CEB to rainwater samples and discussed Che effect of variable solubility on the evaluation of Che soil or road dust factor. 

These methods, when applied to the downtown Phoenix aerosol sample, produced a satisfying range of particle types and left unasslgned only about MJ of the particles (Table I). The major particle type was quartz whldi accounted for 19> of the particles. Various alumino-silicate types were the next most abundant. Easily identifiable types included clusters rich in only one to three elements, including iron (7il), calciun Oil), calciun-silicon-lron (4H), calciun-sulfur (1J), lead OS), lead-chloride-bromide OS) and titanium (2S). The abundances of these particle types, indicated in parentheses, vary widely from site to site. Many particles rich in heavy metals were found in the unassigned group at this point. 

Cluster Composition for Representative Phoenix Aerosol Sample... 

PLS (partial least squares) multiple regression technique is used to estimate contributions of various polluting sources in ambient aerosol composition. The characteristics and performance of the PLS method are compared to those of chemical mass balance regression model (CMB) and target transformation factor analysis model (TTFA). Results on the Quail Roost Data, a synthetic data set generated as a basis to compare various receptor models, is reported. PLS proves to be especially useful when the elemental compositions of both the polluting sources and the aerosol samples are measured with noise and there is a high correlation in both blocks. 

An obvious limitation to the use of bulk analysis studies is the direct result of sample heterogeneity. Not only do aerosol samples show wide variability in the physico-chemical characteristics of different particles, but even a single airborne particle may be highly heterogeneous. With regard to the latter, the surface chemical composition of a particle may bear little resemblance to that of its interior (11-14). 

Fig. 9. GC-MS TIC traces for silylated total extracts of soil, river sediment and aerosol samples (a) Amazon Forest soil (Manaus, Brazil) (b) almond orchard agricultural field soil (CA, USA) (c) Harney River sediment in Everglades National Park (FL, USA), and (d) Gosan Island (Korea) aerosol during Asian dust event (April 27—28, 2001). Numbers refer to carbon chain length of homologous series ( = rj-alkane, o = rj-alkanol, A = rj-alkanoic acid, DHA = dehydroabietic acid, ik = isoprenoid ketone, S = sitosterol). 

Yttri, K. E., Dye, C., Slordal, L. H., and Braathen, O. A., Quantification of monosaccharide anhydrides by liquid chromatography combined with mass spectrometry Application to aerosol samples from an urban and a suburban site influenced by small-scale wood burning. Journal of the Air and Waste Management Association 55(S), 1169-1177, 2005. 

In an aerosol sampling and analysis program, a large number of samples, n, are taken and analyzed for many elemental concentrations. Thus, a large matrix of data is obtained. We can think of plotting the values obtained In a multidimensional space. 

A Varimax rotation (Vl ) is often used to achieve it. However, simple structure may not be the most useful criterion for environmental source resolution since an element may be present in an aerosol sample because of its emission by several sources. The variance should, therefore, be spread over several factors rather than concentrated in one. 

Source contributions assigned to the same aerosol sample have varied greatly in intercomparison studies (23) but, without the intermediate particle property classifications, it is impossible to ascribe the differences to the analytical portion or to the source assignment portion of the process. 

Aerosol sampling instruments were housed in an air conditioned monitoring trailer operated by NWC. The particle light scattering coefficient, bg, was continuously measured with modified MRI Model 1561 integrating nephelometer. The nephelometer automatically zeroed daily and was calibrated quarterly. 

Elemental mass distribution - The aerosol sampled by the LPI for elemental analysis was impacted on coated mylar films affixed to 25 mm glass discs. The mylar had been coated with Apiezon L vacuum grease to prevent particle bound. The LPI samples were sent to Crocker Nuclear Laboratory for elemental analysis by PIXE using a focused alpha particle beam of 3 to 4 mm diameter. Nanogram sensitivities for most elements were achieved with the focused beam. A detailed description of the PIXE focused beam technique applied to LPI samples can be found in Ouimette (13). Based upon repeated measurements of field samples, the estimated measurement error was about 15-20% or twice the minimum detection limit, whichever was larger. 

Sulfur mass distribution - The aerosol sampled by the LPI for sulfur analysis was impacted on vaseline-coated stainless steel strips backed by 25 mm glass discs. The sulfur mass deposited on each stage was determined by the technique of flash volatilization and flame photometric detection (FVFPD)(15). 

The quality of statistically inferred species extinction balances can be enhanced with proper aerosol sampling. Due to its important role in light scattering, only the fine aerosol should be sampled. A mass balance should account for all major fine particle species. Ideally the particle scattering coefficient should be measured directly at the location where aerosol is sampled by the filters. The importance of soot and other carbonaceous aerosol contributions to light extinction in arid regions should not be overlooked. 

Aerosol samples for composition measurements were collected using the Caltech low pressure impactor (LPI) (21,22). This fully calibrated instrument classified particles into eight size fractions between 0.05 and 4 ym aerodynamic diameter. Collection of particles smaller than 0.3 ym is achieved by reducing the pressure and increasing the velocity of the jets. 

The authors thank Dr. James Ouimette for assistance in collecting aerosol samples for analysis. This work was supported... 

Sampling. Four aerosol samples were collected isokinetically on July 26, 1979, at ports on the inlet duct of the ESP at Plant A two were taken with 62-mm fluoropore filters and two were taken with the University of Washington MKV Cascade impactor (1 ). At plant D, samples were collected over a 6-day period at ports both in the outlet duct of the ESP (i.e., upstream of the FGD system) and at the 91-m level of the stack. Eleven fluoropore filter, 1 MKV, and 4 MKIII impactor samples at each location, giving a total of 22 filter, and 8 MKIII samples. A single MKV sample was also collected in-stack at reduced pressure at plant D during the 6-day period. Polycarbonate material coated with apiezon L vacuum grease and 62 or 47-mm-diam, l-pm pore Fluoropore filters were used as back-up filters in the MKV impactor. 

More complex substances, however, showed higher degrees of pyrolytic conversion. In aerosol samples collected from the combustion of distillate and residiaal oil, 31 and 25% respectively of the organic carbon underwent pyrolytic conversion to elemental carbon. Lesser amounts of conversion were observed for leaded and unleaded auto exhaust samples, and no conversion occurred in a diesel truck exhaust sample. Biological samples also showed large degrees of conversion e.g., 45% of the carbon associated with wood fiber was pyrolytically converted to elemental carbon. 

Delumyea, R.G. Chu, L.-C. Macias, E.S. "Determination of elemental carbon component of soot in ambient aerosol samples", Atmos. Environ., 1980, 14, 647-652. 

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