Maximum Ground Level Concentration Research Articles

Effects of anthropogenic emission sources on maximum ozone concentrations over Greece

The impacts of anthropogenic emissions from the maritime transport and from the countries neighboring Greece on the maximum ground-level ozone concentrations over Greece were studied. Ozone concentrations were simulated across a part of the Eastern Mediterranean during a summer period using a modeling system that consisted of the photochemical Urban Airshed Model known as UAM-V coupled with the meteorological mesoscale model known as MM5. Simulated, maximum hourly ozone concentrations were higher over continental and maritime areas of Greece influenced by the emissions of the large urban agglomerations. When air quality simulations were performed assuming zero maritime transport emissions, the greater part of Greece experienced reductions in maximum ozone levels. Over the continental part of the country, the largest ozone reductions occurred along the coastline of southern and western Greece and were approximately 20 ppb. Over maritime areas, the decreases in maximum ozone concentrations were more pronounced. However, in the regions influenced by high amounts of nitrogen oxides emitted from the sea transport activities, the O 3 concentrations were increased. The impact of anthropogenic emissions from all continental areas within the modeling domain, other than Greece, on the maximum ozone concentrations over Greece was small. Considering that the emission inventory for Greece was more detailed, while the official emission data for some of the countries in the modeling domain were generally poor, the assessed impact might have been underestimated.

Comparison of the Industrial Source Complex and AERMOD Dispersion Models: Case Study for Human Health Risk Assessment

Air quality models are typically used to predict the fate and transport of air emissions from industrial sources to comply with federal and state regulatory requirements and environmental standards, as well as to determine pollution control requirements. For many years, the U.S. Environmental Protection Agency (EPA) widely used the Industrial Source Complex (ISC) model because of its broad applicability to multiple source types. Recently, EPA adopted a new rule that replaces ISC with AERMOD, a state-of-the-practice air dispersion model, in many air quality impact assessments. This study compared the two models as well as their enhanced versions that incorporate the Plume Rise Model Enhancements (PRIME) algorithm. PRIME takes into account the effects of building downwash on plume dispersion. The comparison used actual point, area, and volume sources located on two separate facilities in conjunction with site-specific terrain and meteorological data. The modeled maximum total period average ground-level air concentrations were used to calculate potential health effects for human receptors. The results show that the switch from ISC to AERMOD and the incorporation of the PRIME algorithm tend to generate lower concentration estimates at the point of maximum ground-level concentration. However, the magnitude of difference varies from insignificant to significant depending on the types of the sources and the site-specific conditions. The differences in human health effects, predicted using results from the two models, mirror the concentrations predicted by the models.

Prediction of CO maximum ground level concentrations in the Bay of Algeciras, Spain using artificial neural networks

The region of the Bay of Algeciras is a very industrialized area where very few air pollution studies have been carried out. The main objective of this work has been the use of artificial neural networks (ANNs) as a predictive tool of high levels of ambient carbon monoxide (CO). Two approaches have been used: multilayer perceptron models (MLPs) with backpropagation learning rule and k-Nearest Neighbours (k-nn) classifiers, in order to predict future peaks of carbon monoxide. A resampling strategy with twofold cross-validation allowed the statistical comparison of the different topologies and models considered in the study. The procedure of random resampling permits an adequate and robust multiple comparisons of the tested models and allow us to select a group of best models.

Computer simulated versus observed NO2 and SO2 emitted from elevated point source complex

ISC-AERMOD dispersion model was used to predict air dispersion plumes from an diesel power plant complex. Emissions of NO 2 and SO 2 from stacks (5 numbers) and a waste oil incinerator were studied to evaluate the pollutant dispersion patterns and the risk of nearby population. Emission source strengths from the individual point sources were also evaluated to determine the sources of significant attribution. Results demonstrated the dispersions of pollutants were influenced by the dominant easterly wind direction with the cumulative maximum ground level concentrations of 589.86 µg/m 3 (1 h TWA NO 2 ) and 479.26 µg/m 3 (1 h TWA SO 2 ). Model performance evaluation by comparing the predicted concentrations with observed values at ten locations for the individual air pollutants using rigorous statistical procedures were found to be in good agreement. Among all the emission sources within the facility complex, SESB-Power (diesel power plant) had been singled out as a significant source of emission that contributed >85% of the total pollutants emitted.

Developing new correlations and uncertainty analysis for the prediction of ground-level and maximum ground-level concentrations

The determination of Ground Level Concentration (GLC) and Maximum Ground Level Concentration (MGLC) is useful for the prediction of violations for air quality regulations. In this study, the predictions of GLC and MGLC when using different existing empirical formulas are analysed and the effect of dispersion parameters is investigated. Sensitivity analysis studies using both a first order and a second order Taylor series approach are carried out. The dispersion coefficients are assumed to be of a power law form and are used in conjunction with the Gaussian plume model in order to calculate the sensitivity coefficients.

A comparison of nearby incremental ground level and in plant concentrations of air pollutants emitted from electronics facilities

Air dispersion modeling by was recently conducted to predict the incremental ground level and in- plant concentrations of toxic organic chemicals due to stack and fugitive emissions from Sama Jaya Free Industrial Zone (SJFIZ), Kuching, Sarawak, Malaysia. Simulations of organic air pollutants emitted from industrial facilities in SJFIZ from years 1996 to 2001 were carried out in September 2004 by members of Faculty of Engineering, Universiti Malaysia Sarawak (UNIMAS). The results indicated that there were negligible amount of maximum incremental ground level concentrations of less than 3x10 -2 µg/m 3 for 365-day average, and less than 18x10 -2 µg/m 3 for 24 h. average. For in-plant maximum incremental concentrations, it is found that the simulated results were much lower than TWA values, except xylene. The predicted in plant concentration of xylene was 119.21 (parts per million) ppm as compared to ACGIH TLV-TWA of 100 ppm approximately 19% higher than ACGIH recommended values. From this study, it was concluded that both nearby population and in plant workers were not potentially at risk to exposing organic chemicals far lower than the threshold limit levels set by ACGIH.

Modelling of groundlevel particulate concentration from an industrial chimney

Increase in demand for cement has been created as a result of rapid industrialization. Cement production is not without its environmental pollution problems. The pollutants released in a cement industry include oxides of nitrogen, and sulphur, and particulates and volatile organic compounds. Elevated particulate concentrations in conjunction with oxides of sulphur is responsible for rises in respiratory tract diseases. To easily predict maximum ground level particulate concentrations in the atmosphere,models have been generated in this work. Six models having coefficient of determination (r2) values ranging between 0.9735 to 0.9976 have been developed for a range of weather conditions for predicting maximum ground level particulate concentrations as a function pf chimney height.Keywords: particulates, cement industry, maximum ground level concentration, gaussian plume model Global Journal of Environmental Sciences Vol. 4(2) 2005: 147-149

Evaluation of arsenical emission from semiconductor and opto-electronics facilities in Hsinchu, Taiwan

Semiconductor and opto-electronics industries use many chemicals including arsenics in manufacturing processes. Thus, the process vent stream contains toxic air pollutants including arsine and other arsenic compounds, and poses a potential source for the atmospheric arsenic. Limited data are published on arsenic risk assessment and work place condition for electronics industries. Moreover, as per our best knowledge there is no report available on arsenic pollution from the exhaust of semiconductor and opto-electronic industries. In this study, the total arsenic (arsenic compounds as arsenic in gaseous and particulate phase) concentration was measured in the flue gas of 20 stacks of different semiconductor and opto-electronics facilities situated in Science Based Industrial Park (SBIP), Hsinchu, Taiwan during August–September 2002. Ambient concentration of particulate arsenic (arsenic compounds as arsenic) was measured at 15 sites of SBIP twice, i.e. in September and October 2002. The concentration of the total arsenic in the flue gas was from 0 to 55.92 μg m −3 with the emission rate from 0 to 0.1427 g h −1 for the facilities. The ambient arsenic concentration was from 0 to 120 ng m −3. The ambient air level goal (AALG) of arsenic compound is 4.6×10 −5 μg m −3, if the lifetime cancer probability (LCP) level is 1.0×10 −6. Based on simple risk assessment model, we used Industrial Source Complex Short Term 3 (ISCST3) model to calculate the maximum ground level concentration and employed the value of AALG; the emission limit of arsenic compounds from a factory was determined to be less than 1.0×10 −5 kg h −1. On comparison, it was concluded that the arsenical emission of 11 out of 20 facilities was higher than the limited value.

A MATLAB-based modeling and simulation program for dispersion of multipollutants from an industrial stack for educational use in a course on air pollution control

In this article, a MATLAB program for a three-dimensional simulation of multipollutants (CO, NOx, SO2, and TH) dispersion from an industrial stack using a Multiple Cell Model is presented. The program verification was conducted by checking the simulation results against experimental data and Gaussian Model and better agreements were obtained in comparison with the Gaussian model. The effects of meteorological and stack parameters on dispersion of pollutants like, wind velocity, ambient air temperature, atmospheric stability, exit temperature, velocity, concentration, and stack height can be easily studied using the program. Several illustrations for reducing maximum ground level concentrations using the program are given. The program can simulate all industrial stacks and only needs meteorological data and stack parameters. The outputs from the program are presented in graphical form. The program was designed to be user friendly and computationally efficient through the use of variable pollution grids, vectorized operations, and memory pre-allocation. © 2006 Wiley Periodicals, Inc. Comput Appl Eng Educ 14: 300–312, 2006; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20089

Effects of atmospheric circulation and boundary layer structure on the dispersion of suspended particulates in the Seoul metropolitan area

A three-dimensional non-hydrostatic numerical model and lagrangian particle model (random walk model) were used to investigate the effects of the atmospheric circulation and boundary layer structure on the dispersion of suspended particulates in the Seoul metropolitan area. Initially, emitted particulate matter rises from the surface of the city towards the top of the convective boundary layer (CBL), owing to daytime thermal heating of the surface and the combined effect of an onshore wind with a westerly synoptic-scale wind. A reinforcing sea-valley breeze directed from the coast toward the city of Seoul, which is enclosed in a basin and bordered by mountains to its east, disperses the suspended particulate matter toward the eastern mountains. Total suspended particulate concentration (TSP) at ground level in the city is very low and relatively high in the mountains. Radiative cooling of the surface produces a shallow nocturnal surface inversion layer (NSIL) and the suspended particulate matter still present near the top of the CBL from the previous day, sinks to the surface. An easterly downslope mountain wind is directed into the metropolitan area, transporting particulate matter towards the city, thereby recycling the pollutants. The particulates descending from the top of the NSIL and mountains, combine with particulates emitted near the surface over the city at night, and under the shallow NSIL spread out, resulting in a maximum ground level concentration of TSP in the metropolitan area at 2300 LST. As those particles move toward the Yellow Sea through the topographically shaped outlet west of Seoul city under the influence of the easterly land breeze, the maximum TSP concentration occurs at the coastal site. During the following morning, onshore winds resulting from a combined synoptic-scale westerly wind and westerly sea breeze, force particulates dispersed the previous night to move over the adjacent sea and back over the inland metropolitan area. The recycled particulates combine with the particulates emitted from the surface in the central part of the metropolitan area, producing a high TSP and again rise towards the top of the CBL ready to repeat the cycle.

Study on an ozone episode in hot season in Hong Kong and transboundary air pollution over Pearl River Delta region of China

Abstract An ozone (O3) episode that occurred in Hong Kong during 18–22 August 1999 was investigated. This episode lasted nearly 2 days with Typhoon Sam located at 500 km away from Hong Kong in the southeast. The maximum ground-level concentration of O3 reached 334 μg m−3, which violated the Hong Kong Air Quality Objective for O3 (240 μg m−3, 1 h). The visibility was reduced to 3.2 km and UV radiation was reduced by 50%. Investigations of local meteorological factors revealed that cloudless sky with high temperature and weak wind was responsible for the formation of O3, which was trapped by sea-breeze circulations developed under stable atmospheric conditions. Backward trajectories indicated that transboundary transport induced by synoptic northwest wind due to the cyclone system played a critical role in this episode. It carried aged air mass of O3 as well as its precursors from areas with heavy emissions. The PATH (Pollutants in the Atmosphere and their Transport over Hong Kong) model system was used to simulate the flow field and O3 concentration. The computed results were basically consistent with field observations. Comparison with measurements showed that the model generally performed well in simulating flow structure over coastal complex terrain. The computed O3 peaks at most stations were underestimated by 10%, which might be due to the uncertainty in NOx and VOC emission inventory in the study region. The H2O2/HNO3 ratio of 0.8–1.2 was identified to be the transition value for separating NOx- and VOC-sensitive regimes of O3 chemistry. A process analysis further revealed the importance of horizontal transport in all physical and chemical evolution phases. Sensitivity study suggested that regional transport contributed to 60–90% of O3 level at urban and rural areas of Hong Kong during the study period.

An application of a puff dispersion model on power plant emissions in Yatagan region, Turkey

The present paper describes the application of the CALMET meteorological model and CALPUFF plume dispersion model to the Yatagan district to study the impact of Yatagan Power Plant emissions on the SO2 levels on December 2000 in the region. Results indicate that SO2 concentrations over the city depend strongly on advected emissions from the power plant and on the local variation of the wind field and limited vertical mixing conditions. It is found that South Westerly and light winds and the night time surface inversion layers lead to accumulation of pollutants coming from the power plant over the Yatagan district. The results are compared with the observations obtained from Local Environmental Authorities of Mugla. The simulation results indicate that the maximum ground level concentrations were found northeast from the source, which agrees with the measurements, but differ in terms of magnitudes.

대기경계층과 연안순환에 의한 부유입자의 재순환

The dispersion of suspended particulates in the coastal complex terrain of mountain-inland basin (city)-sea, considering their recycling was investigated using three-dimensional non-hydrostatic numerical model and lagrangian particle model (or random walk model). Convective boundary layer under synoptic scale westerly wind is developed with a thickness of about I km over the ground in the west of the mountain, while a thickness of thermal internal boundary layer (TIBL) is only confined to less than 200m along the eastern slope of the mountain, below an easterly sea breeze circulation. At the mid of the eastern slop of the mountain, westerly wind confronts easterly sea breeze, which goes to the height of 1700 m above sea level and is finally eastward return flow toward the sea. At this time, particulates floated from the ground surface of the city to the top of TIBL go along the eastern slope of the mountain in the passage of sea breeze, being away the TIBL and reach near the top of the mountain. Then those particulates disperse eastward below the height of sea-breeze circulation and widely spread out over the coastal sea. Total suspended particulate concentration near the ground surface of the city is very low. On the other hand, nighttime radiative cooling produces a shallow nocturnal surface inversion layer (NSIL) of 200 m thickness over the inland surface, but relatively thin thickness less than 100m is found near the mountain surface. As synoptic scale westerly wind should be intensified under the association of mountain wind along the eastern slope of mountain to inland plain and further combine with land-breeze from inland plain toward sea, resulting in strong wind as internal gravity waves with a hydraulic jump motion bounding up to about 1km upper level in the atmosphere in the west of the city and becoming a eastward return flow. Simultaneously, wind near the eastern coastal side of the city was moderate. Since the downward strong wind penetrated into the city, the particulate matters floated near the top of the mountain in the day also moved down along the eastern slope of the mountain, reaching the. downtown and merging in the ground surface inside the NSIL with a maximum ground level concentration of total suspended particulates (TSP) at 0300 LST. Some of them were bounded up from the ground surface to the 1km upper level and the others were forward to the coastal sea surface, showing their dispersions from the coastal NSIL toward the propagation area of internal gravity waves. On the next day at 0600 LST and 0900 LST, the dispersed particulates into the coastal sea could return to the coastal inland area under the influence of sea breeze and the recycled particulates combine with emitted ones from the ground surface, resulting in relatively high TSP concentration. Later, they float again up to the thermal internal boundary layer, following sea breeze circulation.

Recycling of suspended particulates by the interaction of sea-land breeze circulation and complex coastal terrain

The dispersion of recycled particulates in the complex coastal terrain surrounding Kangnung city, Korea was investigated using a three-dimensional non-hydrostatic numerical model and lagrangian particle model (or random walk model). The results show that particulates at the surface of the city that float to the top of thermal internal boundary layer (TIBL) are then transported along the eastern slope of the mountains with the sea breeze passage and nearly reach the top of the mountains. Those particulates then disperse eastward at this upper level over the coastal sea and finally spread out over the open sea. Total suspended particulate (TSP) concentration near the surface of Kangnung city is very low. At night, synoptic scale westerly winds intensify due to the combined effect of the synoptic scale wind and land breeze descending the eastern slope of the mountains toward the coast and further seaward. This increase in speed causes development of internal gravity waves and a hydraulic jump up to a height of about 1 km above the surface over the city. Particulate matter near the top of the mountains also descends the eastern slope of the mountains during the day, reaching the central city area and merges near the surface inside the nocturnal surface inversion layer (NSIL) with a maximum ground level concentration of TSP occurring at 0300 LST. Some particulates are dispersed following the propagation area of internal gravity waves and others in the NSIL are transported eastward to the coastal sea surface, aided by the land breeze. The following morning, particulates dispersed over the coastal sea from the previous night, tend to return to the coastal city of Kangnung with the sea breeze, developing a recycling process and combine with emitted surface particulates during the morning. These processes result in much higher TSP concentration. In the late morning, those particulates float to the top of the TIBL by the intrusion of the sea breeze and the ground level TSP concentration in the city subsequently decreases.

Intercomparison of atmospheric dispersion models

An intercomparison between Gaussian, Gaussian segmented plumes and Lagrangian codes is presented. The codes chosen for the simulation of a gaseous emission under real meteorological conditions were AERMOD, HPDM, PCCOSYMA and HYSPLIT. The emission source was located at 37.35°N and 78.24°W in a flat terrain. The meteorological data were obtained from RAMS code output. The AERMOD and HPDM meteorological preprocessors results were analyzed. The main differences found are originated in the sensible heat flux (SHTF) and u * (friction velocity) computation, whose values impact directly on the Monin–Obukov length and mixing height calculation. These differences and the strong dependence of the results on them indicate that more development should still be done in order to improve the algorithms for the meteorological variables calculations, mainly during stable conditions. A more realistic description is performed by the segmented Gaussian plume model (PCCOSYMA) respect to the Gaussian ones (AERMOD, HPDM) because it limits the plume length along the wind direction. It also predicts reasonably well the contaminant cloud rotation respect to the Lagrangian code (HYSPLIT) as no major difference between the wind field and the wind at the source location is present in the analyzed case. During the stable hours, HPDM calculates the most stable situation and the lowest mixing heights. Because of this there is a considerable discrepancy in the maximum ground level concentration respect to the other codes. While during the unstable hours HPDM calculates the most unstable situation, nevertheless the maximum ground level concentrations predicted by all the Gaussian and Lagrangian codes are comparable.

Air pollutant concentration and its location under different thermal stability classes

¶The Gaussian plume model for the dispersion of pollutants released to the atmosphere from an elevated point source has been presented assuming perfect reflection at ground surface. An analytic treatment for both the maximum ground-level concentration and its downwind location for different stability categories have been obtained. The effective release height modification was taken into consideration. An illustrative case study namely, the emission from the research reactor at Inchas, has been studied. The results of both analytical treatments and semi-empirical formula are discussed and presented in illustrative diagrams.

SO2 dispersion and monthly evaluation of the industrial source complex short-term (ISCST32) model at Mina Al-Fahal refinery, Sultanate of Oman.

Modeling of air pollutant dispersion has been undertaken for emissions of sulfur dioxide (SO(2)) at the Mina Al-Fahal refinery in the Sultanate of Oman. The study was conducted during the period of November 1999 to October 2000. The Industrial Source Complex Short-Term (ISCST32) air pollution model was adopted to predict the ground level concentration of SO(2) in and around the refinery. The modeling results were validated against measured data during the study period. The comparison, based on the monthly average measurements, showed that the model underestimates the observed SO(2) concentrations. However, the predicted ground level concentrations of SO(2) during the months of September, October, November, and June were in better agreement with the observations. The predicted SO(2) values are presented in the form of concentration contours to determine the spatial distribution of SO(2) and to assess the impact on air quality over the survey area. Predicted SO(2) concentrations were found lower than the World Health Organisation (WHO) guideline value of 365 microg/m(3), with the maximum ground level concentrations being found to occur relatively close to the sources of emission. Moreover, concentration contour patterns for the modeled area vary with changes in meteorological conditions. On the basis of this study, the refinery is not likely to cause any significant deterioration in air quality, and predicted concentrations of SO(2) are well below those likely to influence health.

Wind tunnel experiment of tracer gas diffusion within unstable boundary layer over coastal region

A wind tunnel experiment was carried out to simulate stack gas diffusion within an unstable atmospheric boundary layer over a coastal region. The wind tunnel floor, 4 m leeward of the entrance of the test section, was heated to 90°C over a length of 6 m in the streamwise direction, and wind tunnel experiments were performed under the flat plate condition with a prototype-to-model length scale ratio of 1200. Three similarity criteria of flow fields in the wind tunnel and in atmosphere, viz., bulk Richardson number, surface Reynolds number and the ratio of the Peclet number to the Richardson number, were considered in the wind tunnel experiment. Tracer gas was released along the coastline at a height of 10 cm, which corresponded to 120 m in height in atmosphere. The obtained wind tunnel experimental results of ground level concentration were compared with 30-min average values of the field experiments, viz., the data from the Tokai 82 field experiment. The maximum ground level concentration and its location were accurately simulated when there was close similarity between the wind tunnel and atmospheric flow conditions. The maximum concentration increased and occurred closer to the source when the level of convection was relatively stronger in atmosphere.

Gaseous contaminant emissions as affected by burning scrap tires in cement manufacturing.

We studied the environmental impact (gaseous emissions) of using scrap tires as a fuel substitute at a cement plant that produces one million tons of cement per year. Using a combination of tires and coal as opposed to only coal caused variations in the pollutant emission rate. The study recorded a 37% increase in the rate of emission for CO, a 24% increase for SO2, an 11% decrease for NOx, and a 48% increase for HCl when tires were included. The rate of emission for metals increased 61% for Fe, 33% for Al, 487% for Zn, 127% for Pb, 339% for Cr, 100% for Mn, and 74% for Cu, and decreased 22% for Hg. On the other hand, the emission rate of organic compounds dropped by 14% for polycyclic aromatic hydrocarbons, 8% in naphthalene, 37% in chlorobenzene, and 45% in dioxins and furans. We used a Gaussian model of atmospheric dispersion to calculate the average pollutant concentration (1-h, 24-h, and annual concentrations) in the ambient air at ground level with the help of the ISC-ST2 software program developed by the USEPA. When tires were used, we observed (i) a 12 to 24% increase in particulate matter, this range considering the concentration variation depending on the average used (1-h, 24-h, and annual basis), 31 to 52% in CO, 22 to 34% in SO2, 39 to 52% in HCl, 12 to 27% in Fe, -3 to 8% in Al, 30 to 37% in Zn, and 270 to 885% in Pb; (ii) a decrease of 8 to 13% in NOx, 9 to 13% in polycyclic aromatic hydrocarbons, 6 to 7% in naphthalene, 32 to 39% in chlorobenzene, and 32 to 45% in dioxins and furans. The results obtained showed that the maximum ground-level concentrations were well within the environmental standards (for operation with only coal as well as for operation with a combination of coal and tires).

면/이동오염원 배출량 공간 할당방식에 대한 고찰

In the present study, space allocation methods of pollutant emission from area and mobile sources are assessed by the actual application to air quality modeling of Pohang area. It is found that the TM-based modeling which allocates emission onto the 1km x 1km sized TM-grid system predicts almost the same mean ground-level concentration as that by the GIS-based modeling which uses geographical information of area and mobile sources directly, while maximum ground-level concentration by the TM-based modeling is predicted considerably lower than that by the GIS-based modeling. Moreover, the problem is found that the TM-based modeling causes deviation of mobile roads. In conclusion, it is anticipated to applying GIS-based modeling for a more accurate assessment of air quality in local scale.