Metal Aerosols Research Articles

Haze and other aerosol components in late winter Arctic Alaska, 1986

Three coarse and five fine aerosol components of different elemental compositions were identified at Barrow, Alaska, from March 17 to April 21, 1986, resolved by absolute principal component analyses of element concentrations in 280 sequential coarse and fine size fraction time step samples. In the coarse (> 2.5 μm), two components C‐1 and C‐2 had abundant Si, S, Cl, K, and Ca, but no Al, and together contained 85% of coarse S. Their compositions resembled expected products of carbonaceous fuel combustion, with Si being volatilized by carbon reduction and other metals volatilized perhaps as chloride salts. C‐1, with high trace metal contents, might be from nonferrous smelting, whereas C‐2, with high Fe, might be associated with conventional coal combustion. Both appeared semi‐aged with respect to acidic gas uptake because the S chemical equivalents were less than those of metals contributing to alkalinity. When combined with Cl, S was close to the metal equivalents, indicating complete acid‐base titration. A strong concentration rise of C‐1 and C‐2 occurred from March 25 to April 2 during a haze event, although C‐1 was also present at other times. Air trajectories showed that air masses arrived at Barrow during the haze event from eastern or northern Europe. The third component C‐3 was a dust aerosol rich in Al that contained high S but low Cl, suggesting saturation with H2SO4 and therefore aged and regional aerosols perhaps typical of the late winter Arctic. No major change in its concentration was observed to correspond to synoptic events. In the fine (< 2.5 μm), five components represent a sea‐salt aerosol, an S‐rich aerosol with some Si, K, Ca, and Fe, a trace metal aerosol, an Al‐rich dust, and a marine product with Br, S, and Cl. The sea‐salt was found only in three plumes when synoptic meteorology and air trajectories suggested origins in the North Pacific. The S‐rich aerosol, accounting for 73% of S and 40% of Si, was enhanced during the haze event by 75%, and existed over the entire period at rather high levels and might be due to SO2 oxidation and condensation on fine Si‐rich particles. The trace metal aerosol was always present and could have been generated from nonferrous smelters at lower latitudes. The Al‐rich dust particles contained 7% of S and were similar to component C‐3. The marine aerosol contained 74% of Br, 69% of Cl, and 20% of S, and could be from oxidation of marine biogenic Br and S gases. All but the sea‐salt were present at Barrow throughout the period, with no clear relation to air trajectories or synoptic meteorology. The results show that certain winter meteorological conditions favor pollutant transport from lower latitudes to the Arctic. But while haze is related to industrial pollutants, other nonpollution products are present in the winter Arctic and may be important constituents of haze. They also show that by careful data reduction and meteorological analysis, the sources and transport pathways of haze may be better understood.

The photoelectric aerosol sensor array as a tool for on line and in situ analysis of heavy metal aerosols

The technique of substance-selective aerosol charging by photoelectron emission was applied to several ultrafine heavy metal aerosols. To enhance the selectivity of the photoelectric aerosol sensor (PAS), an array operating with four different wavelengths (185, 214, 229 and 254 nm) was used. The photoelectric activity at each wavelength and the linearity of the PAS signal was investigated for monodisperse and quasi-polydisperse systems. The aerosol mass concentration was determined by correlation with atomic absorption spectroscopy measurements of filter samples. Pattern recognition was applied to differentiate between four different aerosol systems and to identify common interferences.

Development and Laboratory Investigations of a Denuder Sampling System for the Determination of Heavy Metal Species in Flue Gases at Elevated Temperatures

Abstract A denuder sampling system was developed to measure volatile metals at elevated temperatures. By using the denuder technique it is possible to avoid condensation and adsorption losses in the sampling line. To investigate the behavior of heavy metal species under different physical and chemical conditions, a laboratory scale quartz stack was built. Metal aerosol generators based on evaporation, diffusion and condensation are described. The diameter of the generated particles varied between 0.05–0.3 μm. The day to day reproducibility of the generation varied between 0.6-5.0% for chromium and 2.8–4.0% for cadmium (95% stat. significance). Denuders coated by elemental silver seem to be an efficient means for sampling of elemental Cd at 200°C. The diffusion coefficient of Cd was calculated from experimental data, and the value of (0.42±0.04) cm2/s was obtained. A detection limit of 0.2 μg/m3 for Cd determination can be reached by using a Ag-denuder, when a sampling time of 30 min and a flow rate of 60l...

Possibilities and limitations of the photoelectric aerosol sensor array applied to heavy metal aerosols

The technique of substance-selective aerosol charging by photoelectron emission was applied to several ultrafine heavy metal aerosols. To enhance the selectivity of the Photoelectric Aerosol Sensor (PAS), an array operating with four different wavelengths (185 nm, 214 nm, 229 nm, 254 nm) was used. The photoelectric activity at each wave-length and the linearity of the PAS signal was investigated for monodisperse and quasi-polydisperse systems. The aerosol mass concentration was determined by correlation with atomic absorption spectroscopy measurements of filter samples. Pattern recognition was applied to differentiate between four different aerosol systems and to identify common interferences.

A hydrodynamic model of plasma initiation off irradiated metallic aerosols in vacuum: The diffusive regime

We exploit the analogy between chemical reactions and cascade ionization to study the spatial and temporal dynamics of plasma formation in the vapor that is formed off a metallic aerosol that is being irradiated by a high-energy laser beam, in vacuum. Our hydrodynamic model is valid for relatively low laser fluences (103 J/cm2 for aluminum aerosols) and pulses of the order of nanoseconds or less, when the diffusive approximation may be safely invoked. The main result of our paper is to show that the laser-induced plasma layer around aerosols shows a crossover, from being transparent to being opaque, as the fluence incident upon the aerosol is increased. We use our model of cascade ionization to show that for the laser fluxes for which the model is valid, the plasma in the vapor layer surrounding an aluminum metallic sphere is not dense enough to obscure the laser beam. But for flux levels of 1011 W/cm2 or higher and pulse lengths of 10 ns or longer, the plasma around individual aluminum aerosols becomes very absorbing.

Fractal Characterization of the Structure of Aerosol Agglomerates Grown at Reduced Pressure

Experimentally grown metallic aerosol particles were found to form highly complex shapes. When the ambient pressure at which they were grown was decreased, distinctive changes in their appearance were observed. Fractal analysis was used to characterize these particles and their differences. The analysis was able to distinguish several different growth regimes and explain some of the growth-pressure effects.

The photoelectric aerosol sensor array as instrument for the “on line”-detection of heavy metal aerosols

The photoelectric aerosol sensor array as instrument for the “on line”-detection of heavy metal aerosols

Insights gained from tests of solid armatures with and without payload in a 15 mm EML

Ten roughly cubical armatures made of three different alloys in two different, albeit similar, designs were tested in an 1.5-cm-bore, 1-m-long EML (electromagnetic launcher), partly with lexan payloads. In payload tests, an arc penetrated between armature and payload sometime during launch. In two cases without payload the armatures broke up early in flight and were overtaken by a runaway arc; the remaining three performed as hybrid armatures, even in a design leaving sizeable gaps between armature and rail surfaces. Speeds up to 2.6 km/s were obtained. Remnants of the armatures and payloads were recovered by soft-catch. Whereas in all cases with payload and with runaway arcs the armatures had broken into pieces, all three armatures without payload and no runaway arc were recovered intact. On the rail sides of these, uniform erosion had removed about 2.5 mm of material. Microscopic study showed that this occurred through superficial melting and spraying off of droplets. Part of the resulting metal aerosol redeposited on the rails, protecting them from significant damage.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The atmospheric fate of DI(2-ethylhexyl-)phthalate, adsorbed on various metal oxide model aerosols and on coal fly ash

The atmospheric fate of DI(2-ethylhexyl-)phthalate, adsorbed on various metal oxide model aerosols and on coal fly ash

Cancer incidence among welders: possible effects of exposure to extremely low frequency electromagnetic radiation (ELF) and to welding fumes.

Epidemiological studies of cancer incidence among welders disclose a pooled total of 146 cases of leukemia observed versus 159.46 expected, a risk ratio of 0.92, and 40 cases of acute leukemia observed versus 43.39 expected, a risk ratio of 0.92. For respiratory tract cancer, the pooled total is 1789 cases observed versus 1290.7 expected, a risk ratio of 1.39. Most electric welders are exposed to extremely low frequency electromagnetic radiation (ELF) (magnetic flux densities of up to 100,000 microT), a suspected leukemogen, and to concentrated metallic aerosols (up to 200 mg/m3), which can contain the putative respiratory tract carcinogens Cr(VI) and Ni. The two exposures are usually coincident, since welding with an electric current produces welding fumes. The observation of an excess risk for respiratory tract cancer strongly suggests significant exposure both to fumes and to ELF. The absence of increased risk for all leukemia or for acute leukemia among ELF-exposed welders does not support the hypothesis that the observed excess risk for leukemia or acute leukemia among workers in the electrical trades is due to their ELF exposure, which on the average is lower than that of welders.

Study of metal aerosol systems as a sink for atmospheric SO2

The chemical removal of SO2 in the presence of different aerosol systems has been investigated in laboratory experiments using a dynamic flow reactor. The aerosols consisted of wetted particles containing one of the following substances: MnCl2, Mn(NO3)2, MnSO4, CuCl2, Cu(NO3)2, CuSO4, FeCl3, NaCl. The SO2 removal rate R was measured as a function of the SO2 gas phase concentration (SO2)g, the spatial metal concentration CMe, and the relative humidity rH in the reactor. A first-order dependence with regard to (SO2)g was observed for each type of aerosol. For the Mn(II) and Cu(II) aerosols R was found to be a non-linear function of CMe except for MnSO4 and Cu(NO3)2 particles. The removal rate showed a significant increase with the relative humidity particularly when rH was close to the deliquescence point of the wetted particles. Among the Mn(II) and Cu(II) aerosols investigated Mn(NO3)2 was found to be most efficient for the chemical removal of SO2 at atmospheric background conditions, especially in haze and fog droplets. The results further indicate that the catalytic oxidation of S(IV) in such aerosol systems may be as efficient as its oxidation by H2O2 in cloud water.

Optical scattering by metallic and carbon aerosols of high aspect ratio

The iterative extended boundary condition method (IEBCM) is utilized to calculate scattering and absorption by metallic colloids and carbon aerosols in the 0.4-μm < λ < 10-μm optical wavelength range. The colloids and aerosols were modeled by dielectric spheroids of high aspect ratio. The new IEBCM method is found to be suitable for making calculations for particles with aspect ratios as high as 12. Results are presented for silver and aluminum metallic aerosols as well as for atmospheric aerosols such as soot and iron oxides (magnetite). The various parameters used to examine the convergence of the IEBCM solution, such as the number of subdomain expansions and the size of the incremental change in intermediate object sizes used in the iterative process, are discussed. Using the internal field distribution to test the convergence of the results is also found to be more accurate than the traditional procedure which utilizes extinction and scattering cross-section data.

Surface and bulk chemical analysis on metal aerosols generated by manual metal arc welding of stainless steel

A scanning Auger electron spectroscope and an energy dispersive X-ray analyser were used to compare surface and bulk elemental concentrations of metal aerosols generated by manual metal arc welding of stainless steel. The good lateral resolution of both techniques was utilized by analysing not only the large area sample, but also two different particle populations. The argon ion sputtering in conjunction with Auger electron analysis facilitated the depth profiling of the elements in the particles. Light elements, such as K, Na, Si, F and O, predominated in the first surface atomic layers of the particles. The metals Cr, Ni and Fe were typically located below surface layers of a few nanometers and seemed to be concentrated in large slag-like particles. The sputtering of the samples also revealed that the growth mechanism of the particles depends roughly on the vapour pressures of the elements.

Preparation and properties of metallic aerosol particles

Preparation and properties of metallic aerosol particles

Preparation and properties of metallic aerosol particles

Preparation and properties of metallic aerosol particles

Development of the volatile metal aerosol sampler based on vaporization/condensation

Development of the volatile metal aerosol sampler based on vaporization/condensation

Preparation and properties of metallic aerosol particles

AbstractAlthough particles of metals and metallic derivatives in the form of fume have been a widespread source of industrial wastage and pollution, aerosol generation is useful in the production of fine powders where features of the particles such as shape and surface texture are important. Methods of aerosol formation by dispersion and by condensation are surveyed, and the physical properties of the particles described. Tables of particle characteristics are given for pure metals and alloys. A notable feature of condensation aerosols, intensively studied in recent years, is the variety of shapes and structures that can occur, depending on the pressure and temperature conditions maintained in the generating plant. Progress towards the understanding of the mechanisms responsible for the various types of particle has been made, and attention is drawn to the potential usefulness of the new knowledge in powder manufacture and fume abatement.

Profile fitting analysis of the X-ray powder diffraction pattern of a complicated metal aerosol

Profile fitting analysis of the X-ray powder diffraction pattern of a complicated metal aerosol

Interactions of heavy metals with the pulmonary metabolism of [ 3H]benzo[ a]pyrene

To test the hypothesis that the inhalation of heavy metal aerosols from polluted air or cigarette smoke could alter the metabolism of polycyclic aromatic hydrocarbons, isolated, ventilated, and perfused rat lungs were used to study the effects of NiCl 2, CdCl 2, and CoCl 2 on the pulmonary metabolism of [ 3H]benzo[ a]pyrene ([ 3H]BAP). Five minutes prior to removing the lungs from a rat, 100 μl of isotonic sucrose containing 1 μmole of NiCl 2, CdCl 2, or CoCl 2 was instilled intratracheally. The lungs were placed in the perfusion system and washed free of blood. After 10 min, 5 nmole of [ 3H]BAP dissolved in 100 μl of dimethylsulfoxide was introduced in the arterial circulation. After 45 min, the lungs were homogenized and the homogenates and perfusates were extracted with ethyl acetate:acetone (2:1, v/v) for analysis by HPLC. Binding of [ 3H]BAP metabolites to lung tissue was also determined. The metabolism of [ 3H]BAP was found to be inducible by pretreatment of rats with β-naphthoflavone (80 mg/kg) and to be inhibited by the inclusion of metyrapone (1.0 mM) or indomethacin (0.1 mM) in the perfusate. Instillation of NiCl 2 resulted in a slight inhibition of metabolism. In the presence of CdCl 2, 20% more of the parent compound was metabolized compared to sucrose-treated controls, but the fraction of organic solvent extractable metabolites increased to 213% of controls. CoCl 2 was without effect on [ 3H]BAP metabolism. In all cases, the extent of covalent binding to lung macromolecules was proportional to the extent of metabolism of the [ 3H]BAP. Since heavy metals and polycyclic aromatic hydrocarbons coexist in the same atmospheric aerosols, heavy metal exposure from polluted urban or occupational air or cigarette smoking may have profound effects upon the bioactivity of a common organic carcinogen.

Generation of a lead metal aerosol test atmosphere

Abstract A lead metal aerosol test atmosphere was produced by condensation of lead vapor. Lead metal was heated in a stainless steel tube in a dynamic nitrogen atmosphere to temperatures ranging from 720 to 990 °C. Average particle diameters produced using this generator ranged from 10 to 120 nm with concentrations from 4.5 μg Pb/L of nitrogen to 631 μg Pb/L of nitrogen, respectively. The generated particles were approximately uniform in size distribution and were nearly spherical. The temperature range which gave reproducible concentrations did not coincide with the temperature range which could give uniformity in average particle diameter at through‐the‐oven flow rates of 2000 mL/min.