Repository of works by Caltech published authors.
Group = Environmental Quality Laboratory
Mostrando recursos 1 - 20 de 166
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.
Thermodynamic prediction of the water activity, NH_4NO_3 dissociation constant, density and refractive index for the NH_4NO_3-(NH_4)_2SO_4-H_2O system at 25°C - Stelson, A. W.; Seinfeld, J. H.
The thermodynamic properties, water activity, density and refractive index of NH_4NO_3-(NH_4)_2SO_4-H_2O aerosols are estimated from binary solution data and existing mixing rules. Particle growth is shown to be predictable from the particle composition, the NH_4NO_3-(NH_4)_2SO_4-H_2O phase diagram and the water activity calculation technique of C.L. Kusik and H.P. Meissner (1978, A.I.Ch. E. Symp. 173, 14–20). Good agreement between the theoretical predictions and the experimental measurements of I.N. Tang et al. (1981, Atmospheric Environment15, 2463–2471), J. Thudium (1978,Pageoph. 116, 130–148) and H.H. Emons and W. Hahn (1970, Wiss Z.12, 129–132) is shown. Also, the effect of (NH_4)_2SO_4 on the relative humidity...
Collision efficiencies of diffusing spherical particles: hydrodynamic, van der Waals and electrostatic forces - Valioulis, Iraklis A.; List, E. John
A practical limitation of the application of Smoluchowski's classical estimate for the collisions probability of two diffusing spherical particles in Brownian motion is the non-consideration of interparticle forcves. For suspended particles in water such forces can arise from the disturbance the particle causes in the fluid (hydrodynamic forces), from the cloud of ions which surround an electrically charged particle (double layer forces) or they can be of molecular origin (van der Waals forces). In this paper corrections to Smoluckhowski's collision probability are computed when such forces operate Scoluchowski's collision probability are computed when such forces operate between two approaching particles...
Numerical Simulation of a Sedimentation Basin. 1. Model Development - Valioulis, Iraklis A.; List, E. John
A method for the numerical simulation of a rectangular
sedimentation basin operating under steady or unsteady
conditions is described. The computer model follows the
spatial and temporal development of the influent particle
size distribution toward the outlet of the tank. It is based
on the fundamental mechanisms which govern particle
motion and growth. The model accounts for the variability
of the flow field and the particle size distribution in the
tank and, from the local development of the particle size
spectrum, predicts the overall performance of the settling
Monte Carlo simulation of coagulation in discrete particle-size distributions. Part 2. Interparticle forces and the quasi-stationary equilibrium hypothesis - Valioulis, I. A.; List, E. J.; Pearson, H. J.
Hunt (1982) and Friedlander (1960a, b) used dimensional analysis to derive expressions for the steady-state particle-size distribution in aerosols and hydrosols. Their results were supported by the Monte Carlo simulation of a non-interacting coagulating population of suspended spherical particles developed by Pearson, Valioulis & List (1984). Here the realism of the Monte Carlo simulation is improved by accounting for the modification to the coagulation rate caused by van der Waals', electrostatic and hydrodynamic forces acting between particles. The results indicate that the major hypothesis underlying the dimensional reasoning, that is, collisions between particles of similar size are most important in...
Sulfate accumulation in a sea breeze/land breeze circulation system - Cass, Glen R.; Shair, Frederick H.
An atmospheric tracer study using SF_6 was conducted on July 22, 1977, to examine the origin of the high particulate sulfate concentrations observed in coastal Los Angeles County. It was found that the sea breeze/land breeze circulation system in the Los Angeles Basin both increases the retention time for sulfate formation in the marine environment and causes individual air parcels to make multiple passes over large coastal emissions sources. Day-old sulfur oxides emissions advected out to sea by the land breeze at night were estimated to be the largest single contributor to 24-hour average sulfate air quality over land the...
Ozone and the deterioration of works of art - Shaver, Cynthia L.; Cass, Glen R.; Druzik, James R.
Seventeen artists' watercolor pigment samples and two Japanese woodblock prints were exposed to 0.40 ppm ozone in a controlled test chamber for three months. It was found that several artists' pigments when applied on paper will fade in the absence of light if exposed to an atmosphere containing ozone at the concentrations found in photochemical smog. Alizarin-based watercolors containing
1,2 dihydroxyanthraquinone lake pigments were shown to be particularly sensitive to ozone damage, as were the yellow pigments used in the Japanese woodblock prints tested. Indoor-outdoor ozone monitoring in a Pasadena, CA art gallery confirmed that ozone concentrations half as high as...
Aerosols from a Laboratory Pulverized Coal Combustor - Taylor, D. D.; Flagan, R. C.
A laboratory study has been undertaken to characterize the aerosol produced during pulverized coal combustion. The emphasis in this work has been on the particulate matter present in the flue gases at the inlet to the gas cleaning equipment rather than that leaving the stack. Coal is burned at conditions which simulate the combustion region of coal-fired utility boilers. The combustion products then pass through a series of convective heat exchangers which cool them to normal flue gas temperature. Samples extracted from the cool (400-500°K) combustion products are analyzed for major gaseous products and aerosol properties. The size distribution of...