Coarse Particle Mass Research Articles

Comparison of atmospheric coarse particles at an urban and non-urban site

This paper provides an evaluation of 90 coarse particle mass distributions taken over a 15-month period during 1983–1984 at an urban and a nearby non-urban site located in the midwestern United States. The coarse particles (> 5μm diameter) were sampled in four mass fractions (6–11, 11–20, 20–29, > 29 μm diameter) with the Noll Rotary Impactor. Diurnal and seasonal differences were measured. Samples were collected when the ground was dry, wet and frozen. The shape of the mass distribution was similar for most samples and was well represented by a log-normal distribution. The mass median diameter varied between 15 and 30 μm with an average near 20 μm diameter. The geometric standard deviation average was 2.0. Urban samples had 75 percent more total mass than nonurban samples. At the urban site, concentrations were 50 percent higher during mid-day than at night. Dry ground samples were 30 percent higher than wet ground and 90 percent higher than frozen ground samples. The mass median diameter ( MMD) was dependent on friction velocity ( U ∗ , cm s −1), where MMD = 0.212 U ∗ + 15.7. The correlation coefficient between the two variables was 0.69.

The quartz content and elemental composition of aerosols from selected sites of the EPA inhalable particulate network

The elemental composition and concentration of quartz in ambient aerosols collected on dichotomous filters from the EPA Inhalable Particulate Network (IPN) in 1980 have been determined by X-ray fluorescence and mass calibration methods of X-ray diffraction (XRD). Quartz concentrations were also determined by reference intensity ratio methods of XRD from high-volume (hi-vol) filters from ten U.S. cities and were compared with data obtained from the dichotomous samples. Twenty five individual sites are represented in the quartz analysis phase of the study. These analyses demonstrate that for all IPN sites, an average of only 4.9 (±2.3) weight per cent of the coarse particle mass as measured by the dichotomous samplers consists of quartz and 0.4 (±0.7) weight per cent as quartz in the fine fraction. Continental interior sites show the highest average quartz content as well as the greatest variability. Except for highly industrialized sites, the Coastal regions and Eastern interior sites reveal the lowest quartz concentrations. The quartz levels observed at Research Triangle Park, NC, Seattle, WA, and Portland, OR, are the lowest of the dichotomous data set, whereas those at Boston, MA, and Five Points, CA, represent the highest levels. The Si concentrations obtained from the quartz analyses were compared with Si measured directly by X-ray fluorescence on the same filters. The complete aerosol X-ray spectra from some samples such as Portland, OR, shows that the Si comes primarily from minerals such as feldspars, whereas the Si in the Buffalo, NY, aerosol comes primarily from quartz. The concentration of quartz combined with elemental composition and other crustal or anthropogenic constituents observed on the filters provides a means for developing unique geographical airshed signatures for use in detailed source apportionment studies.

Mass and Elemental Composition of Fine and Coarse Particles in Six U.S. Cities

Inhalable particulate matter (IP) samples have been collected in six U.S. cities in conjunction with an air pollution health study. The IP were collected using dichotomous virtual impactors in two size ranges: fine particles (FP) having aerodynamic diameter (da) <2.5 μm, and coarse particles (CP) with 2.5 μm < da < 15 μm. The mass measurements were determined by beta-gauge attenuation. The elemental composition of the FP and CP were determined by X-ray fluorescence. The means and distributions for FP and CP and selected elemental data highlight the similarities and differences that exist among these cities in the health study. Examining the temporal variations gives additional information on the meteorology and sources influencing the FP and CP fractions of Inhalable particle mass. Differences in the concentration (and ratios) of selected elements have indicated the varying presence of crustal, steel industry, automotive, oceanic and fuel combustion sources in these cities. The noted variation in the conc...

Composition of size-fractionated aerosol in Charleston, West Virginia

Atmospheric aerosols were collected for 21 days in summer 1976 at Charleston, West Virginia, using five dichotomous virtual impactor samplers simultaneously. The samplers fractionated the aerosol into two aerodynamic size ranges, a fine (< 3.5 μm) and a coarse (> 3.5 μm) fraction. Physical and chemical composition of the aerosol in each size range was measured by filter weighing (total mass), proton induced gamma-ray analysis (carbon, nitrogen, and sulfur), X-ray fluorescence (elements heavier than magnesium), ion chromatography (sulfate, nitrate and sodium), and ion selective electrode (ammonium). Fine particle sulfur was found to be in the form of sulfate. Less than 1% of fine nitrogen was in the form of nitrate; more than 99% was present as ammonium ion. The high correlation between fine sulfur and nitrogen ( r = 0.92) and fine sulfate and ammonium ( r = 0.98) and the presence of sulfate and ammonium in the stoichiometric ratio for ammonium sulfate strongly suggest that ammonium sulfate was the main chemical form of fine sulfur and nitrogen. A detailed mass composition was determined for each particle size range, identifying 69 and 60% of the fine and coarse mass, respectively. Ammonium sulfate was the largest single chemical component (411%) of the fine aerosol mass. Carbon was also a large component of both fine and coarse particle mass constituting 16 and 12% respectively. Factor analysis indicated that four factors were sufficient to satisfactorily represent the variance of 26 measured parameters. The factors are characteristic of crustal material, ammonium sulfate, automotive emissions, and an unidentified anthropogenic source or set of sources.