Measurement of Ozone Concentration

A method based on hourly NWS cloud amount reports is presented for developing a simple model to account for cloud cover in the determination of the nitrogen dioxide photolysis rate constant, k ₁ The model is parameterized and verified with direct UV radiometer and k ₁ measurements (vs. time of day) collected by Sickles, et al. ¹ at Research Triangle Park. Application of our model to variable cloud condition situations indicates that significant improvement in k ₁ prediction is obtained by including the influence of cloud cover. Comparison of our model with the radiative transfer calculations of Peterson⁷ indicates that the particular parameterization of k ₁ given here is most representative of average albedo and relatively heavy aerosol loading conditions. Comparison of ozone predictions using hourly averaged k ₁ and instantaneous k ₁ under conditions of varying cloud cover suggest that the errors resulting from averaging k ₁ are largest when variations in solar zenith angle are significant over the hour.     

循环流化床锅炉污染物排放量的环评计算

在常用燃煤锅炉污染物排放量计算经验公式的基础上，结合循环流化床锅炉中石灰石与二氧化硫反应的原理，推算出其污染物排放量及排放浓度的计算公式，并对锅炉污染物排放量的环评计算提出了原则性的建议。     

Surface Air Pollutant Concentration Frequency Distributions: Implications for Urban Modeling

With the development of ambient air quality standards (AAQS), the need arises to describe the characteristics of regional surface air-pollutant concentration frequency distributions. In the evaluation of land use plans, numerous agencies will be concerned with evaluating the effectiveness of emission zoning and/or control actions. On a regional basis, one means of performing this assessment lies in determining the changes in the pollutant frequency distributions resulting from control actions.

This study presents new data concerning the surface air-pollutant concentration frequency distributions observed for area sources and continuous point sources, and compares these distributions with those of the pertinent meteorological variables describing the transport and diffusion of the pollutant. The observed surface air pollutant frequency distributions are compared to those corresponding to simple modeling concepts from either an urban area source or a continuous point source. For an urban source and a relatively inert pollutant like CO, we found that the observed frequency distribution for CO surface air concentration parallels the approximately log-normal frequency distribution of the reciprocal of the wind speed. We show that the constant relating these two well-correlated frequency distributions can be determined either experimentally or with a numerical simulation model of air pollution. The usefulness of numerical models in air pollution is discussed.     

Peak to Mean Pollutant Concentration Ratios for Various Terrain and Vegetation Cover

Many of the new particle sizing instruments utilize light scattering principles to detect and size aerosolparticles. The sensitivity of such nstruments is quite good, although extensive light shielding and focusingmethods must be used. A visible He-Ne gas laser cavity with its low gain is very sensitive to disturbances in its optical cavity and so may provide a new particle sizing approach.     

Turbulent Diffusion Behind Vehicles: Effect of Traffic Speed on Pollutant Concentrations

Recent theoretical and experimental investigations Indicate that turbulent diffusion behind moving vehicles Is Influenced by the speed of the vehicle. Vertical wake induced turbulent diffusion, explicitly treated in the numerical ROADWAY model, is proportional to the square of the wind speed relative to the moving vehicle. Hence, the model predictions of turbulent mixing and pollutant concentrations on and downwind of a roadway are dependent upon the traffic speed. It Is expected from theoretical considerations that the effect of vehicle speed on pollutant concentrations will be more significant during stable atmospheric conditions, because in neutral and unstable conditions the vehicle-wake turbulence is quickly masked by the ambient turbulence. In this study, experimental data are utilized to evaluate the theoretical predictions of the effects of traffic speed on the ambient pollutant concentrations. The effects of vehicle speed upon ambient concentrations are investigated through wind tunnel experiments and field studies that used dual tracers. Consistent with predictions of the ROADWAY model, data obtained near the Long Island Expressway indicate that the influence of traffic speed on the ambient pollutant concentrations Is not significant during unstable and neutral conditions. The Long Island experiment did not provide sufficient field data to assess the model predictions of the traffic speed effect during stable atmospheric conditions.     

Estimation of Pollutant Transport and Concentration Distributions over Complex Terrain of Southern California Using Airborne Lidar

Airborne lidar data collected during the South Coast Air Basin/Southeast Desert Oxidant Transport Study in summer 1981 were used to provide estimates of concentration distributions of particles and oxidants, and of pollutant transport in mountain passes and over mountain slopes. The results support the idea that for certain situations, given a few representative in situ measurements for use in calibration, airborne lidar might be used to develop detailed concentration fields. When combined with appropriate measurements of wind speed profiles with height, useful estimates of pollutant transport flux might also be provided.     

活性炭吸附有机蒸气过程中的初始浓度测定

以PTA生产尾气为实验体系，讨论了在活性炭对有机气体动态吸附过程中，有机气体初始浓度的三种测定方法，即气相色谱法、吸附称量法和气体方程计算法。结果得出，吸附称量法误差最小，其次是气体方程计算法，误差最大的是气相色谱法。     

Measurement and Three-Dimensional Modeling of Airflow and Pollutant Dispersion in an Undersea Traffic Tunnel

Abstract

Airflow and pollutant dispersion in a cross-harbor traffic tunnel were experimentally and numerically studied. Concentrations of the gaseous pollutants CO, NO_x, and total hydrocarbons (THC) at three axial locations in the tunnel, together with traffic flow rate, traffic speed, and types of vehicle were measured. Three-dimensional (3D) turbulent flow and dispersion of air pollutants in the tunnel were modeled and solved numerically using the finite volume method. Traffic emissions were modeled accordingly as banded line sources along the tunnel floor. The results reveal that cross-sectional concentrations are nonuniformly distributed and that concentrations rise with downstream distance. The piston effect of vehicles alone can provide 9–23% dilution of air pollutants in the tunnel, compounded to a 23–74% dilution effect according to the ventilation condition.     

Electrical Measurement of the Mass Concentration of a Self-Preserving Aerosol Size Distribution

Recently fifty-eight measurements of urban aerosol size distributions by Clark have shown that these distributions agree quite well with the self preserving form proposed by Friedlander within the size range of 0.05 to 5 microns radius. This paper shows that for an aerosol obeying the self preserving distribution model, the volume concentration (and, hence, the mass concentration for constant density) is directly proportional to the electric current collected when the aerosol is unipolarly charged, passed through a weak electric field to remove particles smaller than 0.05 micron and then collected by a current collector. It is shown that the linear relation between the mass concentration and collected current is independent of the unipolar charging method used. A test of this theory using Clark’s electric counter data was encouraging and suggests that the electric measurement of urban aerosol mass concentrations by properly designed instruments may be feasible.     

排污单位排污许可证申请说明示例研究

改革后排污许可制实施以来,积累了宝贵的经验和做法,也暴露出了技术层面操作的问题。文中从技术角度探讨分析排污单位的申请材料填报情况,结合有关要求创新性示范制定了“排污单位排污许可证申请说明”,以期做到排污单位“说得清”、核发单位“审得明”,提高排污许可证申请与核发效率。     

Effect of Humidify on Light-Scattering Methods of Measuring Particle Concentration

An experimental investigation was undertaken to isolate and quantitatively determine the effect relative humidity has on the light-scattering ability of aerosols. Both the naturally-occurring ambient aerosol of State College, Pa., and several common test aerosols were used. A measured flow of aerosol was mixed with a measured flow of particle-free air to form a mixture of constant contaminant level; the humidity of this mixture was varied by controlling the moisture content of the clean diluent air. The total light scattered by a given aerosol sample, at various relative humidities, was measured with a Sinclair-Phoenix aerosol photometer (measures the total light scattered in the near forward direction). All measurements were carried out at atmospheric pressure, and after the particulates had an average of 1½ minutes to reach equilibrium with the water vapor. Natural and laboratory-generated aerosols were both tested in this manner.     

Effects of Strength and Position of Pollutant Source on Pollutant Dispersion Within an Urban Street Canyon

A two-dimensional numerical model for simulating airflow and pollutant dispersion inside an urban street canyon was first developed using the FLUENT code, and then it was validated against a wind tunnel experiment. Then the effects of strength and position of pollutant sources on pollutant dispersion within an urban street canyon were investigated numerically. The numerical results showed that the dimensionless pollutant concentrations within the urban street canyon were independent from the source strength. The results also revealed that the pollutant distributions inside the urban street canyon with a two-lane road were influenced significantly by the positions of the two sources: 1) the closer the two sources were to the street center of the canyon, the lower the pollutant concentrations on the leeward wall and at the human respiration level in the leeward footpath became; 2) the pollutant concentrations on the windward wall and at the human respiration level in the windward footpath were not sensitive to the locations of the two sources as long as the source on the windward lane was situated outside the small recirculation zone at the bottom corner of the canyon windward wall; 3) the pollutant concentrations on the lower parts of the windward and leeward walls as well as in the two footpaths increased greatly when the two sources were moved from outside into the small recirculation zones.     

Measurement of Rapid Changes of Odor Concentration by a Signal Detection Approach

For many odorous industrial gases, odor detecrability often involves such low concentrations that the sampling time factor makes physical-chemical methods of analysis impractical. However, a sensory detection method based on signal detection theory has shown itself to be well suited for such studies even at levels near the absolute threshold. Experiments undertaken to assess the method are described.     

The Effect of Analytical Method on Indicated Atmospheric SO2 Concentration

Atmospheric samples collected in several American cities were analyzed for SO₂ concentration using various analytical methods. The methods were: (1) electroconductivity, (2) West-Gaeke, (3) West-Gaeke with membrane prefdter, (4) West-Gaeke with glass-fiber prefilter, (5) hydrogen peroxide, (6) hydrogen peroxide with membrane prefilter, and (7) hydrogen peroxide with glass-fiber prefilter. The relationships among SO₂ data produced by these methods were evaluated statistically. Where statistical differences among methods, at the 95% confidence level, were determined then relationships were further delineated. Factors considered in these comparisons were: (1) location, {2) time of day, (8) concentration range, (4) particulate concentration, and (5) humidity. Laboratory evaluations of these methods show that each method is subject to different interfering substances. Laboratory evaluations of these methods show that each method is subject to different interfering substances. The relationship among methods obtained in these studies will complement these data and perhaps provide for further laboratory and field evaluation of methods used to measure SO₂. The relationship among SO₂ data produced by these methods should be useful in relating atmospheric SO₂ concentration to its effects and to those involved in establishing ambient air quality standards.     

Weekday-Weekend Pollutant Studies of the Los Angeles Basin

Pollutant data from the Los Angeles Basin were analyzed for weekday-weekend differences for the smog months of June through September 1972 and 1973. The pollutants investigated were oxidant, NO, NO₂, total hydrocarbons (HC), CO, and particulates. In order to maintain the diurnal variation, the concentration percentiles were calculated for each weekday and weekend hour.     

A Quantitative Evaluation of the Pollutant Standards Index

The U. S. Environmental Protection Agency has recommended a daily air pollution index for use by State and local air pollution control agencies— the Pollutant Standards Index (PSI). The new index makes use of "segmented linear functions" which convert measured concentrations of each air pollutant into a normalized number. The overall index is reported for the pollutant with the maximum subindex value, or the "critical pollutant."     

Effect of Dust Concentration Upon the Gas-Flow Capacity of a Cyclonic Collector

The flow rate through an industrial gas-cleaning cyclone at a fixed pressure drop is greater when the incoming gas is dusty than when it is clean. This observation by Briggs for a single cyclone tube was extended to multiple tubes, and ike results compared to observations by Soo and Trezek that the fraction factor for turbulent flow in a pipe is less for dusty gas than for clean. Empirical considerations indicated tJtat both of these observations should be connected with a rather large reduction in gas viscosity due to the dust. This predicted viscosity decrease was later observed. A physical theory accounting for viscosity reduction by a dust cloud is proposed. This effect also offers a means for increasing the heat, transfer coefficient in gas heat exchangers.