Repository of works by Caltech published authors.
Group = Environmental Quality Laboratory
Mostrando recursos 1 - 20 de 160
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...
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...
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...
Lignin pyrolysis products, lignans, and resin acids as specific tracers of plant classes in emissions from biomass combustion - Simoneit, Bernd R. T.; Rogge, W. F.; Mazurek, M. A.; Standley, L. J.; Hildemann, L. M.; Cass, G. R.
Biomass smoke aerosols contain thermally unaltered and partially altered biomarker compounds from major vegetation taxa. These compounds range from C_8 to C_(31) and include phytosterols, lignans, phenolic products from lignin, and diterpenoids from resins. Certain of the higher molecular weight biomarkers are vaporized from the parent plant material and subsequently condense unaltered into the particle phase. Other compounds undergo pyrolytic alteration and possibly dimerization. In both cases it is possible to assign many of these compounds to the plant taxa of the unburned fuel. The diterpenoids are good indicators for smoke from burning of gymnosperm wood. The relative distribution of...
Mathematical modeling of urban organic aerosol: properties measured by high-resolution gas chromatography - Hildemann, Lynn M.; Cass, Glen R.; Mazurek, Monica A.; Simoneit, Bernd R. T.
Primary fine aerosol emissions from a variety of urban
sources have been quantitatively characterized via high-resolution
gas chromatography to obtain organic mass
distribution fingerprints. To assess the degree of secondary
organic aerosol formation in urban areas, a
transport model is used to predict the distribution of
ambient organic aerosol characteristics that would exist
at various sites in the Los Angeles Basin if the primary
organic emissions were transported without chemical
reaction. Comparisons between the model predictions and
ambient measurements show substantial agreement for
the nonpolar organics, suggesting that ambient concentrations
of this organic fraction result directly from primary
emissions. In contrast, ambient concentrations of fine
acidic organic aerosols are significantly underpredicted
by the model, indicating...
Colorado River Project. Phase I: Water Rights and Allocations - Burness, H. Stuart; Quirk, James P.
While this section is concerned with the institutions pertaining
to the Colorado River specifically, the approach to them is tangential
so as to allow the extant institutions to be embedded in the underlying
set of alternative policies and institutions, and thus provide a deeper
appreciation of the status quo. This serves to indicate the appropriateness
(or lack thereof) of present institutions in some cases or at least
their arbitrariness. As matters of equity are difficult and often impossible
to assess, we observe only the legal and technical efficiency
of the institutions and water laws.
Dispersal of Wastewater in the Ocean - A Cascade of Processes at Increasing Scales - Brooks, Norman H.
One of the important uses of the ocean is to receive certain types
of wastes from human developments, such as municipal wastewater and
sludge, thermal power-plant effluents, mine tailings, and dredge spoils.
An effective disposal system is one which must be carefully
designed and operated like any other important engineering system. The
physical part of the disposal system is the submarine outfall pipe with
its associated components -- a multi-port diffuser, a pumping system
and/or a drop structure at the beginning of the pipe. Or in case of
dumping of sludge or dredge spoils, the physical parts are the ships or
barges which carry the wastes to designated offshore...
A Research Plan for Deep-Ocean Disposal of Sewage Sludge off Orange County, California - Brooks, Norman H.; Arnold, Robert G.; Koh, Robert C. Y.; Jackson, George A.; Faisst, William K.
A seven-year research plan has been developed to study
the environmental and possible health effects of a proposed
outfall for the discharge of sewage sludge into the ocean. The proposed pipeline would be constructed to an unprecedented depth of about 300-400 m off the coast of Orange County in southern California. Anticipated environmental effects associated with marine sludge disposal would be minimal at that depth. Approval
to conduct this experiment is being sought through special legislation and regulatory actions at both state and federal levels. Because a sludge outfall serving the County Sanitation Districts of Orange County would be about four or five...
Factors Governing the pH, Availability of H^+, and Oxidation Capacity of Rain - Morgan, J. J.
The acidity of rain is coupled to redox reactions in air and in atmospheric water. The pH, an intensive quantity,
needs to be distinguished from the base neutralizing
capacity. For acidic rain observed at most locations, H_2SO_4, HNO_3, NH_3, and CaCO_3 are dominant components. Their local availability or production rates govern net acidity. pH is thus almost entirely determined by these major "strong" components imposed on a CO_2 background, with some influence by SO_2(aq), smaller concentrations of HNO_2 and weak organic acids and minor bases, e.g., Fe_2O_3, yielding acid aquo metal ions. Total global emissions to tfie atmosphere of H_2SO_4 precursors outweigh...
Dry deposition of nitrogen containing species - McRae, Gregory J.; Russell, Armistead G.
Nitrogen oxides (NO_x) emissions and the oxidation products formed by photochemical interactions in the atmosphere are responsible for a significant fraction of both dry and wet acid deposition fluxes. In his paper a vertically-resolved, Lagrangian trajectory model is used to predict the diurnal variation of: NO, NO_2, NO_3, HONO, HONO_2, HO_2NO_2, RONO, RONO_2, RO_2NO_2, N_2O_5 and PAN over an urban airshed. Particular attention is given to the fate of nitric acid and its reaction with gaseous ammonia to form, aerosol phase, ammonium nitrate. A simple model for estimating the deposition fluxes of these species is also presented. A study of...
The dynamics of nitric acid production and the fate of nitrogen oxides - Russell, Armistead G.; McRae, Gregory J.; Cass, Glen R.
A mathematical model is used to study the fate of nitrogen oxides (NO_x) emissions and the reactions responsible for the formation of nitric acid (HNO_3). Model results indicate that the majority of the NO_x inserted into an air parcel in the Los Angeles basin is removed by dry deposition at the ground during the first 24 h of travel, and that HNO_3 is the largest single contributor to this deposition flux. A significant amount of the nitric acid is produced at night by N_2O_5 hydrolysis. Perturbation of the N_2O_5 hydrolysis rate constant within the chemical mechanism results in redistribution of...
Acquisition of regional air quality model validation data for nitrate, sulfate, ammonium ion and their precursors - Russell, Armistead G.; Cass, Glen R.
An intensive field study was conducted throughout California's South Coast Air Basin to acquire air quality model validation data for use with aerosol nitrate formation models. Aerosol nitrate, sulfate, ammonium, other major ionic aerosol species, nitric acid gas and ammonia were measured concurrently at ten sites for forty-eight consecutive hours during the period 30–31 August 1982. Ozone, NO and NO_x were measured at all locations, and PAN was measured at Pasadena and Riverside, completing a nitrogen balance on the air masses studied.
The product of the measured nitric acid and ammonia concentrations ranged from less than 1 ppbv^2 to greater than...
Ammonia and nitric acid concentrations in equilibrium with atmospheric aerosols: Experiment vs theory - Hildemann, Lynn M.; Russell, Armistead G.; Cass, Glen R.
The equilibrium between gaseous ammonia, nitric acid, and aerosol nitrate is discussed on the basis of a recent field experiment in southern California. Comparison is drawn between theoretical equilibrium calculations and simultaneous measurements of nitric acid, ammonia, ammonium ion, nitrate ion, sulfate ion, other ionic species, temperature and dewpoint. Particulate and gaseous pollutant concentrations at some inland sampling sites are readily explained if the aerosol is assumed to exist as an external mixture with all particulate nitrate and ammonium available to form pure NH_4NO_3. At other monitoring sites, especially near the coast, aerosol nitrate is found in the presence of...
Emissions and air quality relationships for atmospheric trace metals - Cass, Glen R.; McRae, Gregory J.
Atmospheric particulate matter samples taken in urban and rural locations can be analyzed routinely for more than forty trace elements. With the increasing use of automated X-ray fluorescence and neutron activation analyses (Dzubay, 1977; Cooper, 1973), the cost of trace metals determination in airborne particulate samples has been greatly reduced. As a result, large volumes of data are being acquired that
contain considerable chemical resolution, including concentration data on toxic trace elements like lead, arsenic, cadmium and nickel.
Considerations for design of source apportionment studies - Gordon, Glen E.; Pierson, William R.; Daisey, Joan M.; Lioy, Paul J.; Cooper, John A.; Watson, John G., Jr.; Cass, Glen R.
This report recommends procedures for source and ambient sampling and analysis in source apportionment studies. The recommendations are based on the results of receptor model studies of atmospheric particles in urban areas, especially a recent study of Houston, TX, undertaken as part of the Mathematical and Empirical Receptor Models Workshop (Quail Roost II). The recommendations are presented at three levels of increasing cost and detail of information obtained. Existing mass emissions inventories combined with chemically resolved test data from similar sources (not necessarily in the same locale) can be used to initially estimate the sources of elements present on ambient...
Particle Wall Loss Rates in Vessels - Crump, James G.; Flagan, Richard C.; Seinfeld, John H.
Aerosol particle wall loss rates were determined experimentally in a spherical continuous stirred tank reactor.
Tbe particle size and mixing rate dependences are shown
to agree with
the theoretical result of Crump and Seinfeld, in which the
particle loss coefficient β is related to particle diffusivity D, particle settling velocity r, the coefficient of the eddy diffusivity k_e, and vessel radius R. For the vessel used in these experiments, k_e was found to be proportional to the 3/2 power of the volumetric now rate, in accordance with theoretical expectations. Results of a similar nature may be expected to hold in vessels of...
An experimental study of the oxidation of sulfur dioxide in aqueous manganese sulfate aerosols - Crump, James G.; Flagan, Richard C.; Seinfeld, John H.
A continuous stirred tank reactor is used to study growth of manganese sulfate (MnSO_4) aerosols due to catalytic oxidation of SO_2 in humid air. Humidities ranged from 91–97% and SO_2 concentrations from 0 to 92 ppm. The results of the growth studies are consistent with the rate expression for production of sulfuric acid:
d[H_2SO_4]/dt=(8.3±2.5)x10^(-5)/[H^+]Ms^(-1). This expression is estimated to hold for [Mn^(2+)] ⩾ 0.O1 M and [SO_2] ⩾ 10 ppm.
Further Results on Inversion of Aerosol Size Distribution Data: Higher-Order Sobolev Spaces and Constraints - Crump, James G.; Seinfeld, John H.
The aerosol size distribution inversion algorithm of Crump and Seinfeld, based on the concept of regularization with generalized cross-validation, is extended to Sobolev spaces of order m. The use of the cross-validation function for choice of an appropriate value of m in a particular application is discussed. An inversion algorithm that constrains the size distribution to be nonnegative is introduced and shown to be of value for sharply peaked distributions.