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Source contributions of suspended particles using Air Quality Model and Receptor ModelWang, Wen-Cheng 21 December 2008 (has links)
Air quality of the Kao-Ping airshed has been the worst of all airsheds which are divided into seven groups by districts in Taiwan. The percentage of annual bad air quality (Pollution Standard Index, PSI > 100) in the Kao-Ping airshed (6.65−13.56%) was twice than it in the Yun-Chia-Nan airshed (2.58−6.98%) during the past decade (1998−2007). Oil refineries, petrol/plastic industries, power plants, and iron/steel/metal plants are the major industries in the Kaohsiung metropolitan area. Due to intensive industrial and traffic activities, the Kao-Ping area has the poorest air quality in Taiwan − either increased ground-level concentrations of particulate matter (PM) or ozone (O3) associated with unfavorable meteorological conditions − particularly between late fall and mid-spring
The temporal and spatial characterization of suspended particles in the Kao-Ping area was analyzed by using TAPM (air quality model) and CMB (receptor model) to understand the contributions of the major emission sources. Estimations using the TAPM model suggest that point-source emissions were the predominant contributors (about 49.1%) to PM10 concentrations at Hsiung-Kong industrial site in Kaohsiung City, followed by area sources (approximately 35.0%) and neighboring transport (7.8%). Because Ping-Tung City (urban) and Chao-Chou town (rural) are located downwind of Kaohsiung City when north or northeasterly winds prevail, the two sites also experience severe pollution events despite the lack of industrial sources; neighboring transport contributed roughly 39.1% to PM10 concentrations at Ping-Tung and 48.7% at Chao-Chou.
Results of CMB (chemical mass balance) modeling show that the main contributors to PM2.5 mass are vehicle exhaust (gasoline vehicle emission: 43% and diesel vehicle emission: 17% at Hsiung-Kong; gasoline vehicle emission: 45% and diesel vehicle emission: 19% at Ping-Tung; gasoline vehicle emission: 12% and diesel vehicle emission: 29% at Chao-Chou). And the main contribution to PM2.5-10 mass is the paved road emission (Hsiung-Kong: 40%; Ping-Tung: 48%; Chao-Chou: 50%). It is recommended that air quality model is an appropriate tool to large area and receptor model is more suitable to specific point to identify emission sources by the results in this study.
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Effects of Automoblie Tailpipe Emissions in the Hsuehshan Tunnel on the Air Quality of Neighboring Areas Using ADMS ModelWang, Chen-wen 30 June 2009 (has links)
The Hsuehshan tunnel, whose length is about 12.9 kilometers, is the longest tunnel in Taiwan and Southeast Asia. Since the tunnel is used, it reduces the traveling time from Taipei to Ilan and brings the convenience of transportation; but the vehicles and pollution sources are added. Furthermore, the concentrations of pollutants are increased by accumulation in the long tunnel.
This study estimates the effects of automobile tailpipe emissions in the Hsuehshan tunnel on the air quality of neighboring areas by using Atmospheric Dispersion Modelling System for Roads (ADMS-Roads). This work simulates carbon monoxide (CO), nitrous oxides (NOx) and sulfur dioxide (SO2) at two sites (Pin-Ling and Tou-Cheng management centers) in northern Taiwan in winter of 2008. The average concentrations of CO, NOx and SO2 at Pin-Ling (Tou-Cheng) management centers respectively are 0.49 (0.55) ppm, 10.60 (14.83) ppb and 4.80 (7.47) ppb on non-holiday and 0.66 (0.64) ppm, 16.88 (15.12) ppb and 4.70 (4.20) ppb on holiday. It shows that the concentrations of pollutants on holiday are higher than on non-holiday by increasing vehicles.
Simulated results show that effects of traffic exhaust in the tunnel on the air quality of neighboring areas are less. Estimations using the ADMS-Roads suggest that the emissions are not the predominant contributors at two sites. The effect is the highest with northern (northeastern) winds at the southern (northern) area of the Hsuehshan tunnel. Comparisons between simulations and measurements at both sites are satisfactory. Simulated values are generally in agreement with measured values, with a correlation coefficient of R = 0.37 ¡V 0.81, the index of agreement (IOA) = 0.58 ¡V 0.77, and the normalized mean square error (NMSE) = 0.03 ¡V 0.25. The ADMS-Roads will be applied to assess the environmental impact while the tunnel will be allowed more types of vehicles to drive in the future.
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Development and Evaluation of a Comprehensive Tropospheric Chemistry Model for Regional and Global ApplicationsZaveri, Rahul A. 05 August 1997 (has links)
Accurate simulations of the global radiative impact of anthropogenic emissions must employ a tropospheric chemistry model that predicts realistic distributions of aerosols of all types. The need for a such a comprehensive yet computationally efficient tropospheric chemistry model is addressed in this research via systematic development of the various sub-models/mechanisms representing the gas-, aerosol-, and cloud-phase chemistries.
The gas-phase model encompasses three tropospheric chemical regimes - background and urban, continental rural, and remote marine. The background and urban gas-phase mechanism is based on the paradigm of the Carbon Bond approach, modified for global-scale applications. The rural gas-phase chemistry includes highly condensed isoprene and a-pinene reactions. The isoprene photooxidation scheme is adapted for the present model from an available mechanism in the literature, while an a-pinene photooxidation mechanism, capable of predicting secondary organic aerosol formation, is developed for the first time from the available kinetic and product formation data. The remote marine gas- phase chemistry includes a highly condensed dimethylsulfide (DMS) photooxidation mechanism, based on a comprehensive scheme available in the literature. The proposed DMS mechanism can successfully explain the observed latitudinal variation in the ratios of methanesulfonic acid to non-sea-salt sulfate concentrations.
A highly efficient dynamic aerosol growth model is developed for condensing inorganic gases. Algorithms are presented for calculating equilibrium surface concentrations over dry and wet multicomponent aerosols containing sulfate, nitrate, chloride, ammonium, and sodium. This alternative model is capable of predictions as accurate for completely dissolved aerosols, and more accurate for completely dry aerosols than some of the similar models available in the literature.
For cloud processes, gas to liquid mass-transfer limitations to aqueous-phase reactions within cloud droplets are examined for all absorbing species by using the two-film model coupled with a comprehensive gas and aqueous-phase reaction mechanisms. Results indicate appreciable limitations only for the OH, HO₂, and NO₃ radicals. Subsequently, an accurate highly condensed aqueous-phase mechanism is derived for global-scale applications. / Ph. D.
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Evaluating Surface Concentrations of NO2 and O3 in Urban and Rural Regions by Combining Chemistry Transport Modelling with Surface MeasurementsRebello, Zena January 2010 (has links)
A base case modelling investigation was conducted to explore the chemical and physical behaviour of ground-level ozone (O3) and its precursor nitrogen dioxide (NO2) in Ontario using the U.S. Environmental Protection Agency (EPA) Community Multiscale Air Quality (CMAQ) model. Two related studies were completed to evaluate the performance of CMAQ in reproducing the behaviour of these species in both rural and urban environments by comparing to surface measurements collected by the Ontario Ministry of the Environment (MOE) network of air quality stations. The first study was a winter examination and the second study was conducted for a period during the summer of the same year. The municipality of North Bay was used to represent a rural setting given its smaller population relative to the city of Ottawa which was the base of the urban site.
Statistical and graphical analyses were used to validate the model output. CMAQ was found to replicate the spatial variation of O3 and NO2 over the domain in both the winter and summer, but showed some difficulty in simulating the temporal allocation of the species. Validation statistics for North Bay and Ottawa showed overall O3 mean biases (MB) of 3.35 ppb and 2.25 ppb, respectively, and overall NO2 MB of -8.75 ppb and -4.37 ppb, respectively for the winter. Summer statistics generated O3 MB of 4.66 ppb (North Bay) and 10.05 ppb (Ottawa) while both MB for NO2 were between -2.20 ppb to -2.55 ppb. Graphical analysis showed that the model was not able to reproduce the lower levels of O3, especially at night, or the higher levels of NO2 during the day at the North Bay site for either season. This was expected since the comparisons were made between point measurements and 36 km grid-averaged model results. The presence of high amounts of NO2 emissions local to the monitoring sites compared to the levels represented in the emissions inventory may also be a contributing factor. The simulations for Ottawa demonstrated better agreement between model results and measurements as CMAQ provided a more accurate reproduction of both the higher and lower mixing ratios of O3 and NO2 during the winter and summer seasons. Results indicate that CMAQ is able to simulate urban environments better than rural ones.
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Evaluating Surface Concentrations of NO2 and O3 in Urban and Rural Regions by Combining Chemistry Transport Modelling with Surface MeasurementsRebello, Zena January 2010 (has links)
A base case modelling investigation was conducted to explore the chemical and physical behaviour of ground-level ozone (O3) and its precursor nitrogen dioxide (NO2) in Ontario using the U.S. Environmental Protection Agency (EPA) Community Multiscale Air Quality (CMAQ) model. Two related studies were completed to evaluate the performance of CMAQ in reproducing the behaviour of these species in both rural and urban environments by comparing to surface measurements collected by the Ontario Ministry of the Environment (MOE) network of air quality stations. The first study was a winter examination and the second study was conducted for a period during the summer of the same year. The municipality of North Bay was used to represent a rural setting given its smaller population relative to the city of Ottawa which was the base of the urban site.
Statistical and graphical analyses were used to validate the model output. CMAQ was found to replicate the spatial variation of O3 and NO2 over the domain in both the winter and summer, but showed some difficulty in simulating the temporal allocation of the species. Validation statistics for North Bay and Ottawa showed overall O3 mean biases (MB) of 3.35 ppb and 2.25 ppb, respectively, and overall NO2 MB of -8.75 ppb and -4.37 ppb, respectively for the winter. Summer statistics generated O3 MB of 4.66 ppb (North Bay) and 10.05 ppb (Ottawa) while both MB for NO2 were between -2.20 ppb to -2.55 ppb. Graphical analysis showed that the model was not able to reproduce the lower levels of O3, especially at night, or the higher levels of NO2 during the day at the North Bay site for either season. This was expected since the comparisons were made between point measurements and 36 km grid-averaged model results. The presence of high amounts of NO2 emissions local to the monitoring sites compared to the levels represented in the emissions inventory may also be a contributing factor. The simulations for Ottawa demonstrated better agreement between model results and measurements as CMAQ provided a more accurate reproduction of both the higher and lower mixing ratios of O3 and NO2 during the winter and summer seasons. Results indicate that CMAQ is able to simulate urban environments better than rural ones.
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Dynamic Behavior Of Water And Air Chemistry In Indoor Pool FacilitiesLester Ting Chung Lee (11495881) 22 November 2021 (has links)
<p>Swimming is the
second most common form of recreational activity in the U.S. Swimming pool
water and air quality should be maintained to allow swimmers, pool employees,
and spectators to use the pool facility safely. One of the major concerns
regarding the health of swimmers and other pool users is the formation of
disinfection by-products (DBPs) in swimming pools. Previous research has shown
that volatile DBPs can adversely affect the human respiratory system. DBPs
are formed by reactions between chlorine and other compounds that are present
in water, most of which are introduced by swimmers, including many that contain
reduced nitrogen. Some of the DBPs formed in pools are
volatile, and their transfer to the gas phase in pool facilities is promoted by
mixing near the air/water interface, caused by swimming and pool features.</p>
<p><a>Swimming pool water treatment processes can play significant roles
in governing water and air quality.</a> Thus, it is reasonable to hypothesize that
water and air quality in a swimming pool facility can be improved by renewing
or enhancing one or more components of water treatment.</p>
<p>The first phase of the study was designed to identify and quantify changes
in water and air quality that are associated with changes in water treatment at
a chlorinated indoor pool facility. Reductions of aqueous
NCl<sub>3 </sub>concentration were observed following the use of secondary
oxidizer with its activator. This inclusion also resulted in significant
decreases in the concentrations of cyanogen chloride (CNCl) and
dichloroacetonitrile (CNCHCl<sub>2</sub>) in pool water. The concentration of
urea, a compound that is common in swimming pools and that functions as an
important precursor to NCl<sub>3</sub> formation, as well as a marker compound
for introduction of contaminants by swimmers, was also reduced after the
addition of activator.</p>
<p>The second phase
of this study involved field measurements to characterize and quantify the
dynamic behavior of indoor air quality (IAQ) in indoor swimming pool
facilities, particularly as related to volatile compounds that are transferred
from swimming pool water to air. Measurements of water and air quality were
conducted before, during, and after periods of heavy use at several indoor pool
facilities. The results of a series of measurements at different swimming pool
facilities allowed for examination of the effects of swimmers on liquid-phase
DBPs and gas-phase NCl<sub>3</sub>. Liquid-phase NCl<sub>3</sub> concentrations
were observed to gradually increase during periods of high swimmer numbers (<i>e.g.</i>, swimming meets), while liquid-phase
CHCl<sub>3</sub> concentration was nearly constant in the same period. Concentrations
of urea displayed a steady increase each day during these periods of intensive
use. In general, the highest urea concentrations were measured near the end of
each swimming meet. </p>
<p>Measurements of IAQ
dynamics during phase 2 of the study demonstrated the effects of swimmers on
the concentrations of gas-phase NCl<sub>3 </sub>and CO<sub>2</sub>, especially
during swimming meets. The measured gas-phase NCl<sub>3</sub> concentration often exceeded the suggested upper
limits of 300 µg/m<sup>3</sup> or 500 µg/m<sup>3 </sup>during swimming
meets, especially during and immediately after warm-up periods, when the
largest numbers of swimmers were in the pool. Peak gas-phase NCl<sub>3</sub> concentrations
were observed when large numbers of swimmers were present in the pools;
measured gas-phase concentrations were as high as 1400 µg/m<sup>3</sup>.<sup> </sup>Concentrations of gas-phase NCl<sub>3</sub> rarely reached
above 300 µg/m<sup>3</sup> during regular hours of operation. Furthermore, the
types of swimmers were shown to affect the transfer of volatile compounds, such
as NCl<sub>3</sub>, from water to air<sub> </sub>in pool facilities. In
general, adult competition swimmers promoted more rapid transfer of these
compounds than youth competition swimmers or adult recreational swimmers. The
measured gas-phase CO<sub>2</sub> concentration often exceeded 1000 ppm<sub>v</sub>
during swimming meets, whereas the gas-phase CO<sub>2</sub> concentration
during periods of non-use of the pool tended to be close to the background
(ambient) CO<sub>2</sub> concentration or slightly more than 400 ppm<sub>v</sub>.
This phenomenon was largely attributed to the activity of swimmers (mixing of
water and respiratory activity) and the normal respiratory activity of
spectators. </p>
<p>IAQ models for
gas-phase NCl<sub>3</sub> and CO<sub>2</sub> were developed to relate the characteristics
of the indoor pool environment to measurements of IAQ dynamics. Several
assumptions were made to develop these models. Specifically, pool water and
indoor air were assumed to be well-mixed. The reactions that were responsible
for the formation and decay of the target compounds were neglected. Two-film
theory was used to simulate the net mass-transfer rate of volatile compounds
from the liquid phase to the gas phase. Advective transport into and out of the
air space of the pool were accounted for. The IAQ model was able to simulate
the dynamic behavior of gas-phase NCl<sub>3</sub> during regular operating hours.
Predictions of gas-phase NCl<sub>3</sub> dynamics were generally less accurate during
periods of intensive pool use; however, the model did yield predictions of
behavior that were qualitatively correct. Strengths of the model include that
it accounts for the factors that are believed to have the greatest influence on
IAQ dynamics and is simple to use. Model weaknesses include that the model did
not account liquid-phase reactions that are responsible for formation and decay
of the target compounds. The IAQ model for NCl<sub>3</sub> dynamics could still
be a useful tool to form the basis for recommendations regarding the design and
operation of indoor pool facilities so as to optimize IAQ.</p><p>Measurements of
CO<sub>2</sub> dynamics indicated qualitatively similar dynamic behavior as NCl<sub>3</sub>. Because of this, it was hypothesized that CO<sub>2</sub>
may represent a surrogate for NCl<sub>3</sub> for monitoring and control of IAQ
dynamics. To examine this issue in more detail, a conceptually similar model of
CO<sub>2 </sub>dynamics was developed and applied. The model was developed to
allow for an assessment of the relative contributions of liquid®gas transfer and respiration by swimmers and spectators to CO<sub>2</sub>
dynamics. The results of this modeling effort indicated that the similarity of
CO<sub>2</sub> transfer behavior to NCl<sub>3</sub> may allow use of CO<sub>2</sub>
as a surrogate during periods with few to no spectators in the pool; however,
when large numbers of spectators are present, the behavior of CO<sub>2</sub>
dynamics may not be representative of NCl<sub>3</sub> dynamics because of
spectator respiration.</p><p></p>
<br>
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Development and Evaluation of an Integrated Approach to Study In-Bus Exposure Using Data Mining and Artificial Intelligence MethodsKadiyala, Akhil 24 September 2012 (has links)
No description available.
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