Recursos de colección

Caltech Authors (132.208 recursos)

Repository of works by Caltech published authors.

Group = Environmental Quality Laboratory

Mostrando recursos 1 - 20 de 178

  1. Seasonal and Spatial Variation of the Bacterial Mutagenicity of Fine Organic Aerosol in Southern California

    Hannigan, Michael P.; Cass, Glen R.; Lafleur, Arthur L.; Busby, William F., Jr.; Thilly, William G.
    The bacterial mutagenicity of a set of 1993 urban particulate air pollution samples is examined using the Salmonella typhimurium TM677 forward mutation assay. Ambient fine particulate samples were collected for 24 hr every sixth day throughout 1993 at four urban sites, including Long Beach, central Los Angeles, Azusa, and Rubidoux, California, and at an upwind background site on San Nicolas Island. Long Beach and central Los Angeles are congested urban areas where air quality is dominated by fresh emissions from air pollution sources; Azusa and Rubidoux are located farther downwind and receive transported air pollutants plus increased quantities of the products...

  2. Prioritizing Testing of Organic Compounds Detected as Gas Phase Air Pollutants: Structure-Activity Study for Human Contact Allergens

    Johnson, Robert; Macina, Orest T.; Graham, Cynthia; Rosenkranz, Herbert S.; Cass, Glen R.; Karol, Meryl H.
    Organic compounds that are used or generated anthropogenically in large quantities in cities can be identified through their presence in the urban atmosphere and in air pollutant source emissions. Compounds identified by this method were screened to evaluate their potential to act as contact allergens. The CASE and MULTICASE computer programs, which are based on the detection of structure-activity relationships (SAR), were used to evaluate this potential. These relationships first are determined by comparing chemical structures to biological activity within a learning set comprised of 458 compounds, each of which had been tested experimentally in human trials for its sensitization potential....

  3. A Dilution Stack Sampler for Collection of Organic Aerosol Emissions: Design, Characterization and Field Tests

    Hildemann, L. M.; Cass, G. R.; Markowski, G. R.
    A dilution stack sampler specifically intended to collect fine organic aerosol from combustion sources while minimizing sample contamination has been designed and tested. The sampler simulates the cooling and dilution processes that occur in the plume downwind of a combustion source, so that the organic compounds which condense under ambient conditions will be collected as particulate matter. The special features of this sampler are described in detail, and compared with other stack sampling systems. The results of both laboratory and field tests of the system are discussed. Collection of organic aerosol using this sampler is compared with collection using EPA...

  4. Atmospheric Carbon Particles and the Los Angeles Visibility Problem

    Larson, Susan M.; Cass, Glen R.; Gray, H. Andrew
    The control of atmospheric primary carbonaceous particles is central to protecting visibility. In the Los Angeles area, fine particulate carbon accounts for 40% of fine particulate mass concentration on an annual average basis and 33% of the fine aerosol mass during summer midday periods. Visibility modeling shows that aerosol carbon contributes up to 39% of the total scattering coefficient and up to 44% of the extinction coefficient in the Los Angeles area during summer midday periods. Using the results of the primary aerosol carbon emission control strategy study by Gray (1986), which determined the least costly set of controls necessary...

  5. Dry deposition and dew chemistry in Claremont, California, during the 1985 nitrogen species methods comparison study

    Pierson, William R.; Brachaczek, Wanda W.; Japar, Steven M.; Cass, Glen R.; Solomon, Paul A.
    Dry deposition of HNO_3 and aerosol nitrate in Claremont, California, during the September 1985 Nitrogen Species Methods Comparison Study was evaluated by means of nylon and Teflon surrogate-surface collectors. Dew chemistry and deposition to dew were also investigated. The nitrate dry deposition was governed largely by HNO_3; most of the dry deposition of inorganic nitrate (defined here as HNO_3(g) plus aerosol nitrate) onto the surrogate collectors occurred in the daytime, reflecting chiefly a greater-than-10-fold diurnal variation in ambient HNO_3 (g) concentration. In the absence of dew, deposition velocities were ~1.3cms^(−3) for HNO_3(g), ~0.2cms^(−1) for aerosol nitrate, and 0.5cms^(−1) for nitrate...

  6. The Ozone Fading of Traditional Natural Organic Colorants on Paper

    Whitmore, Paul M.; Cass, Glen R.; Druzik, James R.
    This report details the results of an ozone exposure experiment performed on a large number of traditional natural organic colorants applied to watercolor paper with no binder. These colorants were exposed in an environmental chamber to an atmosphere containing 0.397 ± .007 parts per million (ppm) ozone at 72°F and 50% RH in the absence of light for 12 weeks. This ozone concentration is typical of that found in the Los Angeles atmosphere during a heavy smog episode. The total ozone dose delivered to the samples is equivalent to about four years of exposure to outdoor air in Los Angeles...

  7. The Ozone Fading of Traditional Japanese Colorants

    Whitmore, Paul M.; Cass, Glen R.
    The colorfastness of several traditional Japanese colorants upon exposure to atmospheric ozone was tested in a chamber exposure experiment. Samples, in the form of colorants applied to paper, dyes on silk cloth, and colorants on a nineteenth- century Japanese woodblock print, were exposed to an atmosphere containing 0•40 parts per million ozone at 220C and 50% RH, in the absence of light, for 12 weeks. Color differences, calculated from the measured diffuse reflectance spectra, were used to assess the rate and extent of the ozone fading. Of the colorants applied to paper, orpiment was the only inorganic pigment that showed...

  8. The Ozone Fading of Traditional Chinese Plant Dyes

    Ye, Yun; Salmon, Lynn G.; Cass, Glen R.
    Silk samples dyed with 12 traditional Chinese plant dyes were examined to measure their rate of fading upon exposure to atmospheric ozone. Samples of the same colorants extracted directly from the dried plant materials and applied to watercolor paper also were tested for their sensitivity to ozone-induced fading. The samples were exposed in a chamber to an atmosphere containing 0.40 parts per million ozone at 25°C ± 1°C and 50% RH, in the absence of light, for 22 weeks. Colorant-on-paper samples produced from the dyes Jiang huang (turmeric), zi cao (gromwell), and zi ding cao (violet) proved to be particularly...

  9. Interpretation of High-Resolution Gas Chromatography and High-Resolution Gas Chromatography / Mass Spectrometry Data Acquired from Atmospheric Organic Aerosol Samples

    Mazurek, Monica A.; Cass, Glen R.; Simoneit, Bernd R. T.
    Major chemical features of the solvent-soluble organic aerosol carbon fraction (i.e., carbon range C_8–C_(36)) are quantified and identified by high-resolution gas chromatography (HRGC) and high-resolution gas chromatography / mass spectrometry (HRGC / MS). Through these methods, bulk characteristics of the atmospheric aerosol are denned and reveal information relating to seasonal variations and specific source contributions to the atmospheric organics complex mixture. Fine aerosol samples from West Los Angeles, CA show lowest monthly average ambient concentrations of the total extractable organic carbon fraction during summer (e.g., 2.03 μg/m^3) and highest levels during winter (e.g., 5.18 μg/m^3), when sampled at 6-day intervals...

  10. Measurements of Particle Deposition Rates Inside Southern California Museums

    Ligocki, Mary P.; Liu, Harvey I. H.; Cass, Glen R.; John, Walter
    Rates of deposition of submicrometer particles were measured inside five Southern California museums using an automated particle-counting technique on a scanning electron microscope equipped with an energy-dispersive X-ray detector combined with bulk chemical analysis. Deposition velocities to vertical and upward-facing horizontal surfaces were determined as a function of particle size for each site by analysis of indoor suspended particles sampled onto filters and particles deposited on vertically and horizontally oriented deposition plates. Measured deposition velocities to vertical indoor surfaces were in the range of 10^(−6) to 10^(−5) m/s at all sites but varied from site to site in terms of...

  11. Molecular Marker Analysis as a Guide to the Sources of Fine Organic Aerosols

    Rogge, W. F.; Cass, G. R.; Hildemann, L. M.; Mazurek, M. A.; Simoneit, B. R. T.
    The molecular composition of fine particulate (D_p ≥ 2 µm) organic aerosol emissions from the most important sources in the Los Angeles area has been determined. Likewise, ambient concentration patterns for more than 80 single organic compounds have been measured at four urban sites (West Los Angeles, Downtown Los Angeles, Pasadena, and Rubidoux) and at one remote offshore site (San Nicolas Island). It has been found that cholesterol serves as a marker compound for emissions from charbroilers and other meat cooking operations. Vehicular exhaust being emitted from diesel and gasoline powered engines can be traced in the Los Angeles atmosphere...

  12. A comparison of measurements of atmospheric ammonia by filter packs, transition-flow reactors, simple and annular denuders and fourier transform infrared spectroscopy

    Wiebe, H. A.; Anlauf, K. G.; Tuazon, E. C.; Winer, A. M.; Biermann, H. W.; Appel, B. R.; Solomon, P. A.; Cass, G. R.; Ellestad, T. G.; Knapp, K. T.; Peake, E.; Spicer, C. W.; Lawson, D. R.
    sing data obtained during the 1985 Nitrogen Species Methods Comparison Study (1988,Atmospheric Environment22, 1517), several measurement methods for sampling ambient NH_3 are compared. Eight days of continuous measurements at Pomona College, a smog receptor site in Los Angeles, provided an extensive data base for comparing the following methods: Fourier transform i.r. spectroscopy (FTIR), three filter pack configurations, a simple and an annular denuder, and the transition flow reactor. FTIR was defined as the reference method and it reported hourly NH_3 concentrations ranging from > 60 to 2280 nmol m^(−3) (1.5−57ppb) during the course of the study, the highest values coming...

  13. Particle Deposition in Museums: Comparison of Modeling and Measurement Results

    Nazaroff, William W.; Ligocki, Mary P.; Ma, Timothy; Cass, Glen R.
    Deposition of airborne particles may lead to soiling and /or chemical damage of objects kept indoors, including works of art in museums. Measurements recently were made of the deposition velocity of fine particles (diameter range: 0.05–2.1 μm) onto surfaces in five Southern California museums. In this paper, theoretical predictions of particle deposition velocities onto vertical surfaces are developed for comparison against the experimental results. Deposition velocities are calculated from data on surface-air temperature difference and near-wall air velocity using idealized representations of the air flow field near the wall. For the five sites studied, the wall-air temperature differences were generally...

  14. Submicrometer Aerosol Mass Distributions of Emissions from Boilers, Fireplaces, Automobiles, Diesel Trucks, and Meat-Cooking Operations

    Hildemann, Lynn M.; Markowski, Gregorry R.; Jones, Michael C.; Cass, Glen R.
    The predominant peak in the mass distribution emitted from each source measured in this study occurs at or below about 0.2 μm in particle diameter, whereas the Los Angeles atmospheric aerosol contains peaks at a variety of sizes in the range between 0.1 and 1.0 μm in particle diameter, including peaks at sizes larger than 0.2 μm. This suggests that considerable modification of the primary aerosol size distribution occurs because of subsequent processes in the atmosphere. The data presented here are intended for use in defining the size distribution of the primary combustion source effluent for use with mathematical models...

  15. Biological input to visibility-reducing aerosol particles in the remote arid southwestern United States

    Mazurek, Monica A.; Cass, Glen R.; Simoneit, Bernd R. T.
    Source contributions of contemporary biological material to remote airsheds of the arid southwestern United States are described. Combined inputs of epicuticular plant waxes and airborne microorganisms range from winter minimum (11.3-26.9 ng/m^3) to summer maximum ambient mass concentrations (21.2-41.4 ng/m^3). Concentrations of aromatic resin acids (Le., dehydroabietic acid and 13-isopropyl-5cu-podocarpa-6,8,11,13-tetraen-l6-oic acid) plus a thermally matured wood smoke marker (i.e., retene) range from 1.2 to 9.6 ng/m^3. Minimum levels of the resin acids and wood smoke marker are observed for the sparse desert vegetation site (low elevation), and maximum levels are found for the transition site of ponderosa pine and pinyon/juniper forest (high elevation). The total wood smoke mass...

  16. Chemical Characteristics of PM_(10) Aerosols Collected in the Los Angeles Area

    Solomon, Paul A.; Fall, Theresa; Salmon, Lynn; Cass, Glen R.; Gray, H. Andrew; Davidson, Arthur
    A PM_(10) monitoring network was established throughout the South Coast Air Basin (SOCAB) in the greater Los Angeles region during the calendar year 1986. Annual average PM_(10) mass concentrations within the Los Angeles metropolitan area ranged from 47.0 µg m^(-3) along the coast to 87.4 µg m^(-3) at Rubldoux, the furthest inland monitoring station. Measurements made at San Nicolas Island suggest that regional background aerosol contributes between 28 to 44 percent of the PM_(10) aerosol at monitoring sites In the SOCAB over the long term average. Five major aerosol components (carbonaceous material, NO- _3, SO=_4, NH+_4, and soil-related material) account...

  17. Aggregate water availability for energy development in the upper Colorado River basin

    Isaacson, Morton S.
    Can a large (significant in national terms) energy-recovery industry be developed in the Upper Colorado River Basin (UCRB), alongside more traditional water uses, without causing a problem in the aggregate quantity of water supplied to the Lower Colorado River Basin?. This report answers that question in a "reasonably conservative" manner by slightly overpredicting demand and underpredicting supply. First, aggregate consumption of water in the UCRB due to water intensive energy industries is calculated as a function of the level of energy production. Reasonably conservative (i.e., on the high side) estimates of unit water requirements for coal-electric generation, coal-slurry pipelines, coal gasification (to produce...

  18. Mathematical modeling and control of the dry deposition flux of nitrogen-containing air pollutants

    Russell, Armistead G.; Winner, Darrell A.; Harley, Robert A.; McCue, Kenneth F.; Cass, Glen R.
    An Eulerian grid-based air quality model has been modified to include a resistance-based dry deposition code. The magnitude and spatial distribution of the dry deposition flux of nitrogen-containing pollutants to the surface of the Los Angeles area was calculated as a function of land use. For August 1982 base case conditions, the dry deposition flux was 247 t of N per day (5 from NO, 49 from NO_2, 7 from PAN, 101 from HNO_3, 59 from NH_3, and 26 from NH4_NO_3), which corresponds to more than half of the daily NO_x emissions to the local atmosphere. The effects of emission...

  19. Sources of fine organic aerosol. 5. Natural gas home appliances

    Rogge, Wolfgang F.; Hildemann, Lynn M.; Mazurek, Monica A.; Cass, Glen R.; Simoneit, Bernd R. T.
    Fine particle emissions from the combined exhaust of a vented natural gas-fired residential space heater plus a water heater have been examined using GC/MS techniques. Organic compounds such as n-alkanes, n-alkanoic acids, PAH, oxy-PAH, aza arenes, and thia arenes have been identified in the exhaust emissions. Total fine particle emission rates are fairly low, with 45.8 ng/kJ (±17.4); thus residential natural gas combustion does not add much to the total fine particulate organic carbon (OC) mass emissions to the urban atmosphere (about 0.1 % for the Los Angeles area). At least 22.5 % of the particle mass emitted consists of...

  20. Sources of fine organic aerosol. 4. Particulate abrasion products from leaf surfaces of urban plants

    Rogge, Wolfgang F.; Hildemann, Lynn M.; Mazurek, Monica A.; Cass, Glen R.; Simoneit, Bernd R. T.
    Green and dead leaves from 62 plant species characteristic of the Los Angeles area were harvested and composited according to the actual leaf mass distribution for that area. To simulate leaf surface abrasion by the wind, the leaf composites were agitated in clean Teflon bags while a purified airstream flowed through. Fine particles (d_p ≤ 2 µm) shed from the leaf surfaces were extracted and analyzed using gas chromatography/mass spectrometry. Organic constituents including n-alkanes, n-alkanoic and n-alkenoic acids, n-alkanols, n-alkanals, terpenoid compounds, and trace amounts of PAH were identified and quantified. n-Alkanes showed similar concentrations in both dead and green...

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