Martin S. Ruthkosky

Measurements of SOx, NOx and aerosol species on Bermuda

During August 1982 and January and February 1983, General Motors Research Laboratories operated an air monitoring site on the southwest coast of Bermuda. The data show that the levels of the NOx and SOx species reaching Bermuda are determined by the direction of the air flow. The highest levels of sulfate (mean = 4.0 μg m−3), nitric acid (126 ppt) and other species are observed when air masses arrive from the northeastern United States while the lowest levels (sulfate = 1.1 μg m−3; nitric acid = 41 ppt) occur during air flow from the SE direction. With westerly air flow, increases in many anthropogenic constituents such as particulate sulfate, lead, elemental carbon, sulfur dioxide, nitrogen dioxide, nitric acid and ozone are observed. These species are generally the lowest during SE winds which bring high concentrations of soil- and crustal-related aerosol species. The source of this crustal material appears to be the Sahara Desert. On the average, the levels of anthropogenic constituents are higher in winter because of frequent intrusions of N American air masses. Conversely, the levels of crustal materials are higher in summer when the SE flow is more prevalent.

The relationships between the chemical composition of fine particles and visibility in the Detroit metropolitan area

During July 1981, a one week intensive study was conducted to determine the identity of the major visibility-reducing species in Detroits summertime atmosphere. To accomplish this goal, fine particulate samples were collected every 4 h and analyzed for sulfates, nitrates, ammonium, elemental and organic carbon, and trace metals. These species were then related statistically to the light scattering and absorption components of the extinction coefficient. The chemical composition of the aerosol during the study appeared to be representative of the summertime aerosol. The fine particle mass, which accounted for 64% of the total mass less than 15 ..mu..m in diameter, was dominated by ammonium sulfate which comprised 50% of the fine mass. The contributors to the observed light extinction were: sulfate and its associated water, 65%; carbon, 20%; Rayleigh scattering, 7%; NO/sub 2/, 4%; and other fine particulate species, 4%. The regression coefficients used to derive these percentages are in excellent agreement with the coefficients derived for other locations. In addition, the results support our previous finding that sulfates are the most efficient light-scattering species per unit mass of dry weight.

Measurements of sulfur oxides, nitrogen oxides, haze and fine particles at a rural site on the Atlantic coast

During August, 1982 and January and February, 1983, General Motors Research Laboratories operated air monitoring sites on the Atlantic Coast near Lewes, Delaware and 1250 km to the east on the southwest coast of Bermuda. The overall purpose of this project was to study the transformations of the principal acid precipitation precursors, NO x and SO x species, as they transport under conditions not complicated by emissions from local sources. In this paper, the measurements of gas and particulate species from Lewes are described and the composition and sources of sulfate aerosol, which is the most important haze-producing species, are investigated. On the average, the total suspended particulate (TSP) concentration was 27.9 μg/m3 while the PM10 (mass of particles with a diameter less than or equal to 10 μm) concentration was 22.0 μg/m3 or 79 percent of the TSP. The PM10 consisted of 6.1 μg/m3 of coarse particles (CPM, diameter = 2.5 − 10μm) and 15.9 μg/m3 of fine particles (FPM, diameter < 2.5 μm). On a mas...

A characterization of the principal PM-10 species in Claremont (summer) and Long Beach (fall) during SCAQS

Abstract As part of the Southern California Air Quality Study (SCAQS), General Motors Research Laboratories made comprehensive air quality measurements during the summer of 1987 in Claremont, CA, and during the fall of 1987 in Long Beach, CA. These locations are typically in the areas of highest pollution for the respective seasons. Claremonts air quality during the summer was characterized by high concentrations of photochemically produced pollutants including ozone (O3), nitric acid (HNO3), particulate nitrate (NO3−) and particulate organic carbon (OC). The highest concentrations of these species were experienced during the daytime sampling period (0600–1800 h) and were associated with transport from the western part of the basin. Long Beachs air quality during the fall was characterized by frequent periods of air stagnation that resulted in high concentrations of primary pollutants including PM-10, OC and elemental carbon (EC) as well as particulate NO3−. Night-time levels of most constituents exceeded daytime levels due to poorer night-time dispersion conditions. At Claremont, OC and NO3− compounds account for 52% of the PM-10 while at Long Beach they account for 67% of the PM-10. On the average, there appears to be sufficient particulate ammonium (NH4+) to completely neutralize the nitrate and acidic sulfates. Significant artifact OC was detected and corrected for at both sites. At Claremont the artifact accounted for 21% of the uncorrected OC mass and 13% at Long Beach. Because of NO3− and NH4+ losses on Teflon filters, the measured PM-10 and fine particulate mass (FPM) had to be corrected. This correction amounted to increasing the average measured FPM and PM-10 by 17 and 12%, respectively, at Claremont, and 8 and 6%, respectively, at Long Beach.

The influence of local and regional sources on the concentration of inhalable particulate matter in southeastern Michigan

During June, July and August 1981, General Motors Research Laboratories collected daily fine (FPM = diameter < 2.5 μm) and coarse (CPM = ⩾ 2.5 μm, ⩽ 15 μm) particulate samples at four sites in southeastern Michigan. Dichotomous air samplers were located at a downtown Detroit site (DSC), a heavily industrialized site in Dearborn (RR), a suburban downwind site in Warren (TC), and an upwind site in Ann Arbor (AA) which behaved like a rural site. Analyses of the spatial variations of the various particulate components revealed the following results. (1) At all four sites the FPM was dominated by regional influences rather than local sources. The site in the industrial sector, RR, had the largest impact of local sources, but even at this site the local influences appeared to be smaller than the regional ones. (2) The regional influences were most pronounced on the sulfate (SO2−4) levels which accounted for the largest fraction (40–50 %) of the FPM. Evidence suggests that much of the observed SO2−4 was transported into the southeastern Michigan study area and was formed primarily via photochemically initiated reactions. (3) Organic carbon (OC) compounds were the second most abundant FPM species accounting for 20–40 % of the mass. OC seems to be controlled by both local and regional organic carbon influences. Vehicular emissions and possibly secondary reactions appear to affect the OC concentrations at the four sites. (4) Elemental carbon (EC), a relatively minor FPM species, appears to be dominated at DSC, RR and TC by local emissions. The EC levels at AA appear to be representative of the regional background as they were similar to the levels observed in rural areas far removed from local sources. (5) The CPM was dominated by local sources. At RR, however, the crustal-like material could only account for 18% of the CPM. This indicates that other local, noncrustal sources dominated the CPM levels at RR.

Surface Modification of Al2O3 Fiber with Binary Nanoparticles using a Dry-Mechanical Coating Technique

Integrating materials with different functionalities into a composite material to obtain synergetic properties has generated considerable interest in various scientific and technical fields. In this study, a dry-mechanical coating process was used to fix nanosized Al2O3 and CuO particles directly onto the surface of Al2O3 fiber substrates by employing high shear and compression forces. The resulting composite materials showed good dispersion and homogeneous distribution of Al2O3 and CuO nanoparticles. Important coating parameters, including initial particle loadings and processing times were investigated for their effects on coating characteristics and product properties. The experimental results showed that the product surface area increased with higher nanoparticle loadings. The degree of dispersion and homogenous distribution of Al2O3 nanoparticles with CuO nanoparticles increased with the processing time. Additionally, the crystalline phase of raw materials was preserved during the coating process under the conditions studied in this work.

Surface Enhancement of Al2O3 Fiber With Nanosized Al2O3 Particles Using A Dry Mechanical Coating Process

Currently, fabrication of composite materials is of great interest in industry. By combining materials of different properties, we can produce new composite materials with synergetic functionality that individual materials do not possess. In this study, Al 2 O 3 nanosized particles were coated on Al 2 O 3 fiber substrates using a dry mechanical coating technique employing high shear and compression forces. The materials thus synthesized had high surface area with good dispersion for enhanced reactivity and were strong to sustain rigorous operation. Operating parameters, including rotor speed, processing time and initial loading percentage were varied to study their effects on the coating condition. The experimental results showed that the product surface area increased as the nanoparticle loading increased. The dispersion of nanoparticles improved as the processing time increased. A higher rotor speed resulted in a shorter product length while the nanoparticle loading had no effect on the product length. The durability test, conducted in a fluidized bed, indicated no significant change of the coating layer after 7 days of continuous testing.