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By controlling fuel-to-air ratio of local reactants, pollutant emissions would be minimized in a proposed two-stage combustor for gas-turbine engines. It would use fuel-rich partial-oxidation stage and air-rich combustion stage to reduce emissions of nitrogen oxide, carbon monoxide and hydrocarbons. Combustor fuel-lean burning limit would be extended simultaneously.
The potential use of isotopically excited energy dispersive X-ray fluorescence (XRF) spectrometry for automated on line fast real time (5 to 15 minutes) simultaneous multicomponent (up to 20) trace (1 to 10 parts per billion) analysis of inorganic pollutants in reclaimed water was examined. Three anionic elements (chromium 6, arsenic and selenium) were studied. The inherent lack of sensitivity of XRF spectrometry for these elements mandates use of a preconcentration technique and various methods were examined, including: several direct and indirect evaporation methods; ion exchange membranes; selective and nonselective precipitation; and complexation processes. It is shown tha XRF spectrometry itself is well suited for automated on line quality assurance, and can provide a nondestructive (and thus sample storage and repeat analysis capabilities) and particularly convenient analytical method. Further, the use of an isotopically excited energy dispersive unit (50 mCi Cd-109 source) coupled with a suitable preconcentration process can provide sufficient sensitivity to achieve the current mandated minimum levels of detection without the need for high power X-ray generating tubes.
A series of Model TFE731-2 engine tests were conducted with the Concept 2 variable geometry airblast fuel injector combustion system installed. The engine was tested to: (1) establish the emission levels over the selected points which comprise the Environmental Protection Agency Landing-Takeoff Cycle; (2) determine engine performance with the combustion system; and (3) evaulate the engine acceleration/deceleration characteristics. The hydrocarbon (HC), carbon monoxide (CO), and smoke goals were met. Oxides of nitrogen (NOx) were above the goal for the same configuration that met the other pollutant goals. The engine and combustor performance, as well as acceleration/deceleration characteristics, were acceptable. The Concept 3 staged combustor system was refined from earlier phase development and subjected to further rig refinement testing. The concept met all of the emissions goals.
Digital analyses of satellite visible data for selected high-sulfate cases over the northeastern U.S., on July 21 and 22, 1978, are compared with ground-based measurements. Quantitative information on total aerosol loading derived from the satellite digitized data using an atmospheric radiative transfer model is found to agree with the ground measurements, and it is shown that the extent and transport of the haze pattern may be monitored from the satellite data over the period of maximum intensity for the episode. Attention is drawn to the potential benefits of satellite monitoring of pollution episodes demonstrated by the model.
To examine chemical transformation within stagnant air masses and the atmospheric processes acting upon such air masses, the United States EPA sponsored a study in the summer of 1980 in the northeastern region of the country. Ten research aircraft and several mobile and stationary surface monitoring platforms participated in an intensive measurement program between 16 July and 15 August 1980. Pollutants of interest included SO2, NO, NO(x), HC, O3, sulfate, nitrate, and aerosols in general. This paper summarizes the activities of these research aircraft. Three aircraft and one helicopter logged a total of 353 flight hours during 100 missions in the program. The flight patterns and data collected for each mission are documented. This summary will allow scientists who are interested in this data base to identify subsets of the data for model development.
A comparative analysis of satellite-observed haze patterns and ground-based aerosol measurements is carried out for July 20-23, 1978. During this period, a significant regional air pollution episode existed across the northeastern United States, accompanied by widespread haze, reduced surface visibility, and elevated sulfate levels measured by the Sulfate Regional Experiment (SURE) network. The results show that the satellite-observed haze patterns correlate closely with the area of reported low surface visibility (less than 4 mi) and high sulfate levels. Quantitative information on total aerosol loading derived from the satellite-digitized data, using an atmospheric radiative transfer model, agrees well with the results obtained from the ground-based measurements.
Applications of the Differential Absorption Lidar (DIAL) technique to the remote sensing of pollutant gases are surveyed. In the DIAl technique, the differential absorption of two laser beams reflected back to a receiver from a target determines the concentration of the gas being studied. The types of instruments available are considered in detail: dye lidar (to measure nitrogen dioxide, sulfur dioxide, and ozone); carbon dioxide laser (for ozone, ethylene, ammonia, and hydrazine), helium-neon laser (for methane); hydrogen fluoride laser (for HF); and tunable diode laser (for nitric oxide and carbon monoxide). DIAL instruments are compared with other optical remote sensors such as Fourier-transform infrared spectrometers, correlation spectrometers (COSPEC and GASPEC), and grating spectrometers; and criteria for the selection of an appropriate gas measuring system are suggested. Laser and other optical remote sensors are found to be cost effective in many cases, despite the fact that they are more costly than point-monitoring systems.
Laser optical system for remote gas pollutant measurements surveyed. Laser systems discussed in published report, and choices of appropriate gasmeasuring instruments and their sensitivities evaluated.
The definitions of noise and noise pollution are examined with emphasis on the psychological, physiological, sociological and economic impacts on personnel and the environment.
In order to utilize satellite measurements of optical thickness over land for estimating aerosol properties during air pollution episodes, the optical thickness was measured from the surface and investigated. Aerosol optical thicknesses have been derived from solar transmission measurements in eight spectral bands within the band lambda 440-870 nm during the summers of 1980 and 1981 near Washington, DC. The optical thicknesses for the eight bands are strongly correlated. It was found that first eigenvalue of the covariance matrix of all observations accounts for 99 percent of the trace of the matrix. Since the measured aerosol optical thickness was closely proportional to the wavelength raised to a power, the aerosol size distribution derived from it is proportional to the diameter (d) raised to a power for the range of diameters between 0.1 to 1.0 micron. This power is insensitive to the total optical thickness. Changes in the aerosol optical thickness depend on several aerosol parameters, but it is difficult to identify the dominant one. The effects of relative humidity and accumulation mode concentration on the optical thickness are analyzed theoretically, and compared with the measurements.
Sensor calibration, rice fields, and sea pollution are to be investigated with respect to shuttle imaging radar-B (SIR-B). It is planned that the resolution characteristics of the SIR-B be evaluated, the sidelobe characteristics of the SIR-B be investigated, and the relationship between backscatter cross section and image intensity be established. The microwave-scattering characteristics of rice fields are to be studied using SIR-B data. The possibility of classifying crops from SIR-B data is to be explored. The characteristics of the radar image of oil-like surface films under several sea surface conditions are to be determined. The absolute measurement capability of the sea surface scattering cross section is to be estimated using the SIR.
The remote monitoring of atmospheric pollutants can now be performed in several ways. Laser radar techniques have proven their ability to reveal the spatial distribution of different species or particles. Classical optical techniques can also be used, but yield the average concentration over a given path and hence no range resolution. One such technique is Differential Optical Absorption Spectroscopy, DOAS. Such schemes can be used to monitor paths that a preliminary lidar investigation has shown to be of interest. Having previously had access to a mobile lidar system, a new system has been completed. The construction builds on experience from using the other system and it is meant to be more of a mobile optical laboratory than just a lidar system. A complete system description is given along with some preliminary usage. Future uses are contemplated.
A case study is presented which demonstrates that measurements of total ozone from a space-based platform can be used to study a widespread air pollution episode over the southeastern U.S. In particular, the synoptic-scale distribution of surface-level ozone obtained from an independent analysis of ground-based monitoring stations appears to be captured by the synoptic-scale distribution of total ozone, even though about 90 percent of the total ozone is in the stratosphere. Additional analyses of upper air meteorological data, other satellite imagery, and in situ aircraft measurements of ozone likewise support the fact that synoptic-scale variability of tropospheric ozone is primarily responsible for the observed variability in total ozone under certain conditions. The use of the type of analysis discussed in this study may provide an important technique for understanding the global budget of tropospheric ozone.
A one-dimensional photochemical model for cloud-topped boundary layers has been developed to include descriptions of gas- and aqueous-phase chemistry and the radiation field in and below the cloud. The model is applied to the accumulation of pollutants during a wintertime episode with low stratus over Bakersfield, CA. The mechanisms of sulfate production and the balance between the concentrations of acids and bases are examined. It is shown that most of the sulfate production may be explained by the Fe(III)-catalyzed autoxidation of S(IV). Another source of sulfate is the oxidation of SO2 by OH in both the gas and the aqueous phase. It is shown that the sulfate production in the model is controlled by the availability of NH3. It is suggested that this explains the balance observed between total concentration of acids and bases.
The hardware for the Mobile Atmospheric Pollutant Mapping System is described. Measurement results using the hardware are reported along with absorption coefficients and measurement sensitivities for a number of molecular species. The factor that limit measurement accuracy and range are considered.
A technique for deriving large-scale pollution parameters from NIR and visible satellite remote-sensing images obtained over land or water is described and demonstrated on AVHRR images. The method is based on comparison of the upward radiances on clear and hazy days and permits simultaneous determination of aerosol optical thickness with error Delta tau(a) = 0.08-0.15, particle size with error + or - 100-200 nm, and single-scattering albedo with error + or - 0.03 (for albedos near 1), all assuming accurate and stable satellite calibration and stable surface reflectance between the clear and hazy days. In the analysis of AVHRR images of smoke from a forest fire, good agreement was obtained between satellite and ground-based (sun-photometer) measurements of aerosol optical thickness, but the satellite particle sizes were systematically greater than those measured from the ground. The AVHRR single-scattering albedo agreed well with a Landsat albedo for the same smoke.
Using aerosol lidars with high spatial and temporal resolution with the possibility of real-time data interpretation can solve a large number of ecological problems related to the aerosol-field distribution and variation and the structure of convective flows. Significantly less expensive specialized lidars are used in studying anthropogenic aerosols in the planetary boundary layer. Here, we present results of lidar measurements of the mass-concentration field around a coal-fired power plant with intensive local aerosol sources. We studied the pollution evolution as a function of the emission dynamics and the presence of retaining layers. The technique used incorporates complex analysis of three types of lidar mapping: horizontal map of the aerosol field, vertical cross-section map, and a series of profiles along a selected path. The lidar-sounding cycle was performed for the time of atmosphere's quasi-stationarity.
Topics presented include the adsorption and reaction of trichlorofluoromethane on various particles, equilibria of the marine multiphase ammonia system, a novel ozone sensor for direct eddy flux measurements, and characterization of the carbonate content of atmospheric aerosols. Also presented are variations in heavy metals concentrations in Antarctic snows, sources of continental dust over Antarctica during the last glacial cycle, an inventory of anthropogenic emissions and air pollution in the USSR, and atmospheric nuclei in the remote free-troposphere.