Elevated Point Source Research Articles

Regional Transport of PM2.5 from Coal-Fired Power Plants in the Fenwei Plain, China.

The Fenwei Plain (FWP) remains one of the worst PM2.5-polluted regions in China, although its air quality has improved in recent years. To evaluate the regional transport characteristics of PM2.5 emitted by coal-fired power plants in the FWP in wintertime, the primary PM2.5, SO2, and NOx emissions from coal-fired power plants with large units (≥300 MW) in 11 cities of the area in January 2019 were collected based on the Continuous Emission Monitoring System (CEMS). The spatial distribution and source contribution of primary and secondary PM2.5 concentrations were investigated using the Weather Research and Forecast (WRF) model and the California Puff (CALPUFF) model. The results showed that secondary PM2.5 was transported over a larger range than primary PM2.5 and that secondary nitrate was the main component of the total PM2.5 concentration, accounting for more than 70%. High concentrations of primary, secondary, and total PM2.5 mainly occurred in the Shaanxi region of the FWP, especially in Xianyang, where the PM2.5 concentrations were the highest among the 11 cities, even though its pollutant emissions were at moderate levels. The PM2.5 concentrations in Sanmenxia and Yuncheng primarily came from regional transport, accounting for 64% and 68%, respectively, while those in other cities were dominated by local emissions, accounting for more than 63%. The results may help to understand the regional transport characteristics of pollutants emitted from elevated point sources over a complex terrain.

Research and analysis of environmental legal compensation mechanisms related to waste incineration in the context of “double carbon”

In the context of “double carbon,” waste disposal has become a critical issue so far, and how to deal with it is the key to ensuring compliance with the double carbon target, the most practical treatment is still incineration, and how to establish the site selection and legal compensation mechanism is crucial. This paper establishes an environmental dynamic monitoring system for waste incineration power plants based on the Gaussian model and successfully solves the health risk of surrounding residents. Regarding the economic compensation issues, we first applied the AHP to analyze the pollutants comprehensively, constructed the judgment matrix, and conducted a consistency test, determined the weight of each index, and integrated various emissions into one pollutant, which is convenient for the concentration of pollutants. Then, by taking into account the effects of wind direction, rainfall, topography, and other factors on the diffusion of pollutants, we calculated the pollutants around the waste incineration power plant site based on the “elevated continuous point source” “diffusion model.” To obtain the concentration distribution, monitoring points were set up at representative locations, and the environmental monitoring system of the waste incineration power plant was established. Finally, Matlab software was used to draw the contour map of pollutant concentration, and the concentration level of pollutants was divided according to waste incineration. Given the income of the power plant, the economic level of the surrounding residents, the amount of compensation from the local government, and the pollution level, economic compensation plans for the surrounding residents were developed. Through analyzing the proposed compensation scheme, it can be known that the compensation scheme can satisfy the surrounding residents. The highlights of this paper can be described as follows: First, the analytic hierarchy process is used to comprehensively consider the pollutants, simplifying the establishment process of the model. Second, the pollutant concentration is graded, and the concentration equivalent map is drawn to make the monitoring point layout more representative. The economic compensation plan is more reasonable and more convincing to the public.

Reynolds-averaged Eulerian simulation of elevated source pollutant dispersion in turbulent boundary layer using concentration diffusivity limiter

In this study, a limiter for turbulent concentration diffusivity, accounting for travel time, was introduced into the Reynolds-averaged Navier-Stokes equations (RANS) and the Eulerian dispersion model. Using conventional modeling of turbulent diffusivity with the simplified gradient diffusion hypothesis and a proposed method with a limiter, pollutant dispersion from an elevated point source in a turbulent boundary layer was predicted and the results validated by using data from an existing wind tunnel experiment. By using conventional modeling, it was difficult to give a good prediction of the entire concentration field by only adjusting the turbulent Schmidt number. In contrast, the proposed method controlled the turbulent diffusivity near the source, and in the downwind region, by adjusting the combination of model parameters in the limiter. As a result, the dispersion characteristics (concentration profile and plume half-width) near the source and in the downwind region were simultaneously well predicted. Finally, a parametric study was conducted on the mean concentration, and the optimal combination of model parameters in the limiter showed improved results of validation metrics ( FB=0.04, MG=1.09,NMSE=0.03,VG=1.14) than the conventional modeling ( FB=−0.11, MG=0.75,NMSE=0.11,VG=1.62).

Dispersion modelling of environmental odours using hourly-resolved emission scenarios: Implications for impact assessments

Regarding air quality, odours have been repeatedly ranked as the number one reason for public complaints to authorities. The most widely used method for assessing odour impacts is dispersion modelling. However, the entire impact assessment chain is permeated with uncertainty, and the role of different sources of uncertainty is not well understood. A critical component of this chain is the emission, the focus of this work. Here we develop modelling analyses for examining the influence of variable emissions against constant emissions on the outcomes of impact assessments. The analyses are built upon six hourly-resolved emission scenarios and one time-invariant scenario applied for the fattening phase of pig production systems. All seven scenarios are configured to treat total emissions due to a mechanically ventilated shed as coming from an elevated point source with an unobstructed vertical release. A total of 378 impact maps from three sites in two countries (Austria and the U.S.) over relatively flat terrain are scrutinised. The influence and relevance of accounting for variability in odour emissions over time depend strongly on the nature of the emissions (e.g., temporal pattern, presence of stochastic and deterministic components) as well as other factors such as building downwash, odour impact criterion and stack height. Altogether, the results suggest that using hourly odour emission rates can improve the confidence in impact assessments compared with the simulations driven by constant emissions. For odour impact criteria based on high-end percentiles, the assumption of constant emissions can be more easily compromised. In contrast, lower percentiles are found to be more robust in offsetting the source emission variability. Results also indicate that the variability in odour emissions might become less of an issue for releases under the influence of downwash than those without obstacle effects. This systematic work is the largest investigation to date on the consequences of incorporating variable emissions when modelling odour impacts. Our findings demonstrate that the emission scenario used as input to dispersion models can play a central role in dictating the conclusions of odour impact assessments. • Modelling analyses were developed to produce 378 odour impact maps for the investigation. • Assuming constant emissions brings a risk of biased impact estimates. • Releases under building downwash effects were less sensitive to the source emission variability. • The ultimate influence of variable emissions hangs upon the prescribed percentile of impact criteria. • More faithful representations of time-varying emissions are needed to ameliorate odour exposure calculations.

High gaseous carbonyl concentrations in the upper boundary layer in Shijiazhuang, China

Oxygenated volatile organic compounds (OVOCs) are important precursors of secondary air pollutants. However, knowledge of the vertical characteristics of OVOCs in the lower troposphere is lacking. Pairs of OVOCs samples were simultaneously collected via 2,4-dinitrophenylhydrazine (DNPH) near the ground and in the upper boundary layer (at 500 m in winter and 600 m in summer) with a tethered balloon in Shijiazhuang in January and June 2019. The samples were analyzed via high-performance liquid chromatography (HPLC), and 26 vertical profiles of 13 OVOCs were obtained in this study. In winter, the average concentrations of the total OVOCs (TOVOCs) in the upper boundary layer and near the ground were 7.9 ± 4.1 ppbv and 5.5 ± 2.8 ppbv, respectively; while in summer, the average concentrations were 7.1 ± 3.5 ppbv and 6.5 ± 2.7 ppbv, respectively. Acetone, formaldehyde and acetaldehyde were the three main components accounting for more than 80% of the TOVOCs. Significant vertical differences were observed before sunrise in winter and in the afternoon in summer. The TOVOCs concentration in the residual layer (8.4 ± 3.6 ppbv) was higher than that near the ground (6.0 ± 2.5 ppbv), while in the summer afternoon, the concentration in the upper mixing layer (ML) (9.5 ± 2.2 ppbv) was higher than that near the ground (5.8 ± 3.1 ppbv). OVOCs sources were examined with a positive matrix factorization (PMF) model. In winter, the small-molecule carbonyls (SMCs) in the upper boundary layer are mainly derived from secondary + long-lived species (68.4%) because volatile organic compounds at high concentrations were oxidized into OVOCs. In summer, the SMCs in the upper ML were mainly affected by elevated industrial point source emissions (42.9%). These data indicate that vertical gradient observations of SMCs are an important supplement to advance current air pollution research.

Multilevel air quality evolution in Shenyang: Impact of elevated point emission reduction

Visibility observed at different altitudes is favorable to understand the causes of air pollution. We conducted 4-years of observations of visibility at 2.8 and 60 m and particulate matter (PM) concentrations from 2015 to 2018 in Shenyang, a provincial city in Northeast China. The results indicated that visibility increased with the increasing height in winter (especially at night), and decreased with height in summer (especially at the daytime). PM concentration exhibited opposite vertical variation to visibility, reflecting that visibility degrades with the increase of aerosol concentration in the air. The radiosonde meteorological data showed that weak turbulence in the planetary boundary layer (PBL) in winter favored aerosols’ accumulation near the surface. Whereas in summer, unstable atmospheric conditions, upper-level moister environment, and regional transport of air pollutants resulted in the deterioration of upper-level visibility. Inter-annual variation in the two-level visibility indicated that the upper-level visibility improved more significantly than low-level visibility, much likely due to the reduction in emission of elevated point sources in Shenyang. Our study suggested that strengthening the control of surface non-point emissions is a promising control strategy to improve Shenyang air quality.

CAMx simulations of the control of anthropogenic emissions on the reduction of ozone formation in Southeast Texas of USA

The elevated point and on-road emission sources have been identified to be the dominant anthropogenic categories contributing to ozone formation in Southeast Texas of USA. In this study, additional CAMx simulations were carried out to quantify the reductions of ozone concentration in response to the reductions of the two emission sources in the amount of 25, 50 and 75% from the Southeast region based on the summertime Ozone Episode provided by the Texas Commission on Environmental Quality (TCEQ). The simulation results were analyzed and reported in the form of Empirical Kinetics Modeling Approach (EKMA) diagrams and further confirmed through additional Ozone Source Apportionment Technology (OSAT) simulations available in CAMx. While the results are observed to be highly depending on the monitor station, they have indicated that the control of elevated point emissions is slightly more effective in ozone reduction than that of on-road emissions. Averagely, a sole reduction of 48.3% from the elevated point source, or a sole reduction of 61.0% from the on-road source, or a combined reduction of 30.0% each from the two sources are required to meet a potential future 8-h ozone NAAQS of 65 ppb. The current study has demonstrated that CAMx simulations are powerful for the practice and the developed methodology is beneficial to potential future practice when new ozone episodes become available.

Evaluation of CMAQ modeling sensitivity to planetary boundary layer parameterizations for gaseous and particulate pollutants over a fjord valley

Abstract Three-dimensional chemical transport models are useful for spatial and temporal analyses of outdoor air quality. However, the suitability of boundary-layer parameterizations for air pollution modeling over deep, coastal valleys has seldom been tested. An evaluation of the Community Multiscale Air Quality (CMAQ) model performance for five planetary boundary-layer schemes (PBL) with the Weather Research and Forecasting (WRF) meteorological driver was conducted at 1-km horizontal resolution for fine particulate matter (PM2.5), sulfur dioxide (SO2) and nitrogen dioxide (NO2) over the Terrace-Kitimat valley of northwestern British Columbia, Canada. The top-ranked schemes were Mellor-Yamada-Nakanishi-Niino Level 3 (MYNN3) for PM2.5 and Mellor-Yamada-Janjic for NO2. Both schemes ranked high for absolute SO2 levels, but the MYJ and Asymmetric Convective Model, version 2 (ACM2) schemes qualitatively emulated peak summertime diurnal concentrations in the near field of elevated point sources. Greater nighttime SO2 concentrations with MYNN3 and Yonsei University PBL schemes, in less agreement with station monitoring 8 km downwind of emissions from tall stacks, suggested sustained pollutant mixing and downward transport within the nocturnal boundary layer. Consequently, for these two schemes with representations of nonlocal mass flux transfers between model layers, inland penetrations of pollutant plumes were farther than those of ACM2, MYJ, and University of Washington schemes. For NO2 and PM2.5 that mainly discharged passively from fugitive, ground-level sources, hence are less accurately quantified than SO2 emissions, the fully local MYJ, and semi-local MYNN3 PBL schemes more reasonably reproduced peak season concentrations than other schemes. It is concluded that for air pollution modeling in rugged, remote areas, the mode of pollutant emissions is important for the choice of a PBL scheme. PM2.5 was consistently underestimated by the various PBL schemes, and aspects for improving CMAQ simulations for a complex environment are discussed.

Two Inversion Layers and Their Impacts on PM2.5 Concentration over the Yangtze River Delta, China

AbstractAn integrated winter field campaign was conducted to investigate the atmospheric boundary layer structure and PM2.5 concentration at three sites over the Yangtze River delta (YRD) in China: Shouxian (a rural area), a site in a northern suburb of Nanjing, and Dongshan (a residential area). Two temperature inversion layers and air pollution events occurred simultaneously from 30 to 31 December 2016, local time, over the YRD. It was found that the two inversion layers were related to the presence of a high pressure system, resulting in divergence in the upper boundary layer and radiative cooling near the ground at night. Dominated by agricultural and residential biomass burning, the surface emission sources from the Shouxian rural area were moderately strong. After the formation of the two inversions, the vertical distribution of PM2.5 concentration below the upper inversion layer was uniform as a result of thorough boundary layer mixing in the earlier hours. During nighttime at the Nanjing site, air pollutant plumes from nearby elevated point sources could not easily diffuse downward/upward between the two inversion layers, which led to a distinct peak in the PM2.5 concentration. At the Dongshan site, the emission sources were weak and the nighttime PM2.5 concentration above 100 m was high. The surface PM2.5 concentration gradually increased from early morning to noon, which was attributed to emissions related to the local residents. The results indicated that the vertical distribution of pollutants was affected by a combination of local emissions, vertical boundary layer structure, and horizontal and vertical transports.

Evolution of the vertical structure of air pollutants during winter heavy pollution episodes: The role of regional transport and potential sources

Knowledge of vertical distribution of air pollutants is important for understanding the mechanisms underlying haze pollution. In this paper, we characterize the vertical structure of air pollutants based on ground-based Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements in the wintertime in Hefei, East China. Both NO2 and aerosol show exponentially decreasing profile with high concentrations concentrated close to the surface, suggesting the major emissions are at ground level. SO2 profiles extend to slightly higher altitudes than NO2, which might be due to the SO2 emissions from elevated point sources (e.g., power plants). Elevated HCHO was observed in the middle layer during noon time, probably indicating that the larger effect of the photochemical formation of atmospheric HCHO rather than direct HCHO emissions. Potential source contribution function (PSCF) and concentration-weighted trajectory (CWT) models were used to evaluate the potential sources of Hefei's air pollution in the lower, middle and upper boundary layer. The results revealed that the major regional source of NO2 and aerosol were located in the northern and eastern part of Anhui and the transport mainly occured in the lower layer. Transported SO2 from the northwestern regions in the middle layer made great contribution to SO2 in Hefei. HCHO was mostly produced locally while the transport of HCHO from potential source areas was negligible. To further explore the potential source contributions affecting haze pollution, PSCF and CWT analysis for heavy haze episodes suggested that the potential source areas for aerosol were almost located in the northern region, the northwestern region, and the YRD region. Our findings provide a more comprehensive understanding for regional transport through the study on potential sources at different altitudes, which are useful for designing collaborative air pollution control strategies on a regional scale.

Analytical Approach for Airpollution Emitted from an Elevated Point Source with Mesoscale Wind

Analytical Approach for Airpollution Emitted from an Elevated Point Source with Mesoscale Wind

Three Dimensional Analytical Model for the Dispersion of Air Pollutants Emitted from Elevated Point Source with Mesoscale Wind and Removal Mechanism

Three Dimensional Analytical Model for the Dispersion of Air Pollutants Emitted from Elevated Point Source with Mesoscale Wind and Removal Mechanism

Estimating airborne particulate emissions using a finite-volume forward solver coupled with a Bayesian inversion approach

We propose a numerical algorithm for solving the atmospheric dispersion problem with elevated point sources and ground-level deposition. The problem is modelled by the 3D advection-diffusion equation with delta-distribution source terms, as well as height-dependent advection speed and diffusion coefficients. We construct a finite volume scheme using a splitting approach in which the Clawpack software package is used as the advection solver and an implicit time discretization is proposed for the diffusion terms. The algorithm is then applied to an actual industrial scenario involving emissions of airborne particulates from a zinc smelter using actual wind measurements. We also address various practical considerations such as choosing appropriate methods for regularizing noisy wind data and quantifying sensitivity of the model to parameter uncertainty. Afterwards, we use the algorithm within a Bayesian framework for estimating emission rates of zinc from multiple sources over the industrial site. We compare our finite volume solver with a Gaussian plume solver within the Bayesian framework and demonstrate that the finite volume solver results in tighter uncertainty bounds on the estimated emission rates.

Lagrangian Particle Method for Local Scale Dispersion Modeling

A deterministic model is developed for radioactive dispersion analysis based on random-walk Lagrangian Particle Dispersion Method (LPDM). A diagnostic 3dimensional mass-consistent wind-field with a capability to handle complex topography can be used to provide input for particle advection. Turbulent diffusion process of particles is determined based on empirical lateral and linear vertical relationships. Surface-level concentration is calculated for constant unit release from elevated point source. A series of 60-second segmented groups of particles are released in 3600 seconds total duration. Averaged surface-level concentration within a 5 meter surface layer is obtained and compared with available analytical solution. Results from LPDM shows good agreement with the analytical result for vertically constant and varying wind field with the same atmospheric stability.

Refining an inverse dispersion method to quantify gas sources on rolling terrain

This paper analyses a trace gas dispersion experiment with multiple point sources and line-averaging laser gas detectors on gently rolling terrain. The objective of the experiment was to establish how well emission rate can be inferred by “inverse dispersion” (ID), using a Lagrangian stochastic wind transport model (WindTrax) that (strictly) is appropriate only in horizontally-homogeneous winds. Measured mean wind speeds at fixed height above ground revealed spatial variation of order ±10% over the site. However the results of the inversion to estimate source strength Q from the concentration field suggest that the unwanted impact of the terrain is adequately compensated by representing detector light paths as curves, approximating their true height above ground. Under that treatment the mean and standard deviation of the ratio QIDM/Q of inferred to true source strength, over an ensemble of 96 fifteen minute intervals, were respectively 〈QIDM/Q〉=1.04 and σQ|Q=0.15, with little distinction between outcomes under unstable and stable stratification. We also used the measurements to study the influence (on the accuracy of retrieved source strength) of discretionary elements of inverse dispersion procedure: data quality criteria; optimal placement of detectors relative to the source(s); and the impact of alternative spatial representations of the source, supposing one had but partial information in that regard. Because the sources were always rather close to the downwind detector, the quality of the inversions was less sensitive to extremes of stratification than has been reported for other trials. Inversions that treated the actual point sources as an aggregate area source proved acceptable, provided this was placed at or near the height of the (true) point sources. An idealized distribution of elevated point sources can also be satisfactory, but bad inversions may result if placement of the token sources is biased in the cross-plot direction relative to the actual source(s).

Cylindrical spreading due to downwind refraction.

Downwind propagation is analyzed for a low level jet (LLJ). The LLJ is characterized by a wind speed maximum (at least 10-20 m/s with peak speeds up to 30 m/s) a few hundred meters above the ground. Close to an elevated point source, such as a wind turbine or an aircraft, spherical spreading results in a 6 dB decrease in sound level per doubling of the distance. Wind turbine noise measurements show that at a transition distance, the downwind propagation changes the spherical spreading into a cylindrical spreading with a 3 dB decrease. It is shown how the transition distance and sound intensity depend on the LLJ parameters. The pivotal phenomenon is the non-coherent superposition of ground reflected rays in the turbulent atmosphere.

Sensitivity of PBL parameterization schemes of Weather Research Forecasting Model and coupling with AERMOD in the dispersion of NOX over Visakhapatnam (India)

AbstractAn attempt has been made to develop a pre‐processor coupler for offline coupling of atmospheric mesoscale model (WRF) with a dispersion model (AERMOD) to estimate the ground level concentrations due to industrial sources over a coastal city, Visakhapatnam, India. To integrate AERMOD in standalone mode, surface and upper meteorological observations and various planetary boundary layer (PBL) parameters with good temporal resolution are required, that are absent for most locations in India. We have developed an integrated WRF‐AERMOD modeling system that gets required PBL parameters the pre‐processor coupler. Using this model, evaluation of the dispersion of nitrogen oxides (NOX) over Visakhapatnam during summer month with emission inventory of elevated point sources of various industries is conducted. Sensitivity studies of PBL schemes of WRF after validation reveal that the non‐local schemes, Yonsei University (YSU) followed by Asymmetric Convective Model version 2 (ACM2), captured well the characteristic variations of surface meteorological variables, vertical atmospheric structure. After validating with monitored air quality data, it is found that the integrated model with YSU followed by ACM2 is good in simulating ground level concentrations of NOX. The present work advocates that the developed modeling system is useful for better assessment of pollution dispersion over coastal regions. © 2015 Curtin University of Technology and John Wiley & Sons, Ltd.

A framework for emissions source apportionment in industrial areas: MM5/CALPUFF in a near-field application

This paper examines the relative source contribution to ground-level concentrations of carbon monoxide (CO), nitrogen dioxide (NO2), and PM10 (particulate matter with an aerodynamic diameter <10 μm) in a coastal urban area due to emissions from an industrial complex with multiple stacks, quarrying activities, and a nearby highway. For this purpose, an inventory of CO, oxide of nitrogen (NOx), and PM10 emissions was coupled with the non-steady-state Mesoscale Model 5/California Puff Dispersion Modeling system to simulate individual source contributions under several spatial and temporal scales. As the contribution of a particular source to ground-level concentrations can be evaluated by simulating this single-source emissions or otherwise total emissions except that source, a set of emission sensitivity simulations was designed to examine if CALPUFF maintains a linear relationship between emission rates and predicted concentrations in cases where emitted plumes overlap and chemical transformations are simulated. Source apportionment revealed that ground-level releases (i.e., highway and quarries) extended over large areas dominated the contribution to exposure levels over elevated point sources, despite the fact that cumulative emissions from point sources are higher. Sensitivity analysis indicated that chemical transformations of NOx are insignificant, possibly due to short-range plume transport, with CALPUFF exhibiting a linear response to changes in emission rate. The current paper points to the significance of ground-level emissions in contributing to urban air pollution exposure and questions the viability of the prevailing paradigm of point-source emission reduction, especially that the incremental improvement in air quality associated with this common abatement strategy may not accomplish the desirable benefit in terms of lower exposure with costly emissions capping. Implications: The application of atmospheric dispersion models for source apportionment helps in identifying major contributors to regional air pollution. In industrial urban areas where multiple sources with different geometry contribute to emissions, ground-level releases extended over large areas such as roads and quarries often dominate the contribution to ground-level air pollution. Industrial emissions released at elevated stack heights may experience significant dilution, resulting in minor contribution to exposure at ground level. In such contexts, emission reduction, which is invariably the abatement strategy targeting industries at a significant investment in control equipment or process change, may result in minimal return on investment in terms of improvement in air quality at sensitive receptors.

Polycyclic aromatic hydrocarbons in river sediments from the western and southern catchments of the Bohai Sea, China: toxicity assessment and source identification

The concentration, distribution, and origin of 16 USEPA priority polycyclic aromatic hydrocarbons (PAHs) were investigated in river sediments from the western and southern catchments of the Bohai Sea, China. A toxicity assessment of 28 sediment samples collected from 15 main rivers was conducted by utilizing threshold and probable effect concentrations (TEC and PEC, respectively) derived from consensus-based sediment quality guidelines. The concentrations of total PAHs (∑PAH(16)) ranged from 0.14 to 10,757 μg/kg dry weight (mean = 1,368.6 μg/kg). The high concentrations of PAHs found in Binhai New Area of Tianjin and Binzhou City are likely the result of rapid population and heavy industry growth, resulting in elevated point and nonpoint source inputs of PAHs. Of the samples collected, samples 1 and 10 (7.1 % of the total) were categorized as toxic since some of the PAH concentrations exceeded the corresponding PECs. Twenty samples were classified as nontoxic, with both the individual PAH and the ∑PAH(16) concentrations falling below the corresponding TECs. Analyses of selected PAH isomer ratios aided in the identification of PAH origins, allowing for a discrimination between pyrogenic and petrogenic sources. Spatial variability confirmed source heterogeneity within the study area. The most significant PAH-associated contamination was found in the Beitang River and Ji Canal, which are located in Binhai New Area. The magnitude of contamination and the likelihood of an ongoing influx of PAHs support the need for a better understanding of pollution sources and methods for both control and sediment restoration.

Verification of a Gaussian Plume Model with Pasquill-Gifford Dispersion Coefficient Algorithm for an Elevated Point Source

Verification of a Gaussian Plume Model with Pasquill-Gifford Dispersion Coefficient Algorithm for an Elevated Point Source