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Modeling of ozone and nitrogen oxides pollutions in urban air environments

Reimer, Henrik LU (2018) FYSK02 20181
Combustion Physics
Department of Physics
Abstract
As the air quality in urban environments is a rising problem, a deeper understanding of how air pollution is dependent on different factors is necessary. In these environments, there are different parameters that effect how the chemical reactions of the pollutants are proceeding. Here the parameters solar radiation, temperature, humidity, emission factors and background concentrations of gaseous air pollutants are at focus. They were chosen as they all contribute to the reactions in the air and results with different outcomes. In the study a box model taking 608 chemical species and 1923 reactions into account is used to simulate how these parameters eects the processes of ozone and NOx (NO and NO2). The model that was used was a merge of... (More)
As the air quality in urban environments is a rising problem, a deeper understanding of how air pollution is dependent on different factors is necessary. In these environments, there are different parameters that effect how the chemical reactions of the pollutants are proceeding. Here the parameters solar radiation, temperature, humidity, emission factors and background concentrations of gaseous air pollutants are at focus. They were chosen as they all contribute to the reactions in the air and results with different outcomes. In the study a box model taking 608 chemical species and 1923 reactions into account is used to simulate how these parameters eects the processes of ozone and NOx (NO and NO2). The model that was used was a merge of a Master Chemical Mechanism (MCM) and Kinetic Pre-Processor (KPP) solver. The effect of each parameter was studied by changing one of them and keeping the rest constant. This was performed for all the parameters. All the simulations was based on a case from London. Even though there are many air pollutants contributing to the poor air quality the ones that this study have its focus on is ozone, nitrogen oxides and some hydrocarbons. This is due to the fact that they all occur naturally, that they are made through the reactions caused by industrial and traffic combustion, that they all interfere with each other, that they contribute to unhealthy environment and that most of them increases the greenhouse effect. The aim is to investigate the sensitivity of urban atmospheric chemistry with respect to different parameters and gain general insights in these important chemical systems and better understanding of in what conditions simpler or more complex modeling schemes can or must be used to reproduce the systems.

It was found that the temperature was important for the processes of ozone and NOx as the rate of significant reactions are highly dependent on temperature. This resulted in both decrescent, in low temperatures, and increasing, in high temperatures, of ozone concentration. Here the humidity also played a role as it at high temperatures contribute to more production of OH radicals which is an important part of the tropospheric chemistry. This as OH is a sink for NOx so an amplified production of OH decreased the NOx. Solar radiation acted expected as a support for ozone production when NO2 is photolyzed. Different ratios of NO2/NOx acted differently on the ozone concentration. When NO2/NOx consisted of mostly NO the concentration of ozone decreased and when NO2/NOx consisted of mostly NO2 it increased. Different ratios did not affect the end concentration of the total NOx. When hydrocarbon compounds and CO was studied an increase produced more ozone and decrease the concentration of NOx. The result was the same when all the volatile organic compounds with CO and when only the non-methane volatile organic compounds was changed. (Less)
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author
Reimer, Henrik LU
supervisor
organization
course
FYSK02 20181
year
type
M2 - Bachelor Degree
subject
keywords
Ozone, Nitrogen oxides, NOx, Hydrocarbons, VOC, Urban environment, Model, Pollutions
language
English
id
8952500
date added to LUP
2018-06-26 12:57:22
date last changed
2018-06-26 12:57:22
@misc{8952500,
  abstract     = {{As the air quality in urban environments is a rising problem, a deeper understanding of how air pollution is dependent on different factors is necessary. In these environments, there are different parameters that effect how the chemical reactions of the pollutants are proceeding. Here the parameters solar radiation, temperature, humidity, emission factors and background concentrations of gaseous air pollutants are at focus. They were chosen as they all contribute to the reactions in the air and results with different outcomes. In the study a box model taking 608 chemical species and 1923 reactions into account is used to simulate how these parameters eects the processes of ozone and NOx (NO and NO2). The model that was used was a merge of a Master Chemical Mechanism (MCM) and Kinetic Pre-Processor (KPP) solver. The effect of each parameter was studied by changing one of them and keeping the rest constant. This was performed for all the parameters. All the simulations was based on a case from London. Even though there are many air pollutants contributing to the poor air quality the ones that this study have its focus on is ozone, nitrogen oxides and some hydrocarbons. This is due to the fact that they all occur naturally, that they are made through the reactions caused by industrial and traffic combustion, that they all interfere with each other, that they contribute to unhealthy environment and that most of them increases the greenhouse effect. The aim is to investigate the sensitivity of urban atmospheric chemistry with respect to different parameters and gain general insights in these important chemical systems and better understanding of in what conditions simpler or more complex modeling schemes can or must be used to reproduce the systems.

It was found that the temperature was important for the processes of ozone and NOx as the rate of significant reactions are highly dependent on temperature. This resulted in both decrescent, in low temperatures, and increasing, in high temperatures, of ozone concentration. Here the humidity also played a role as it at high temperatures contribute to more production of OH radicals which is an important part of the tropospheric chemistry. This as OH is a sink for NOx so an amplified production of OH decreased the NOx. Solar radiation acted expected as a support for ozone production when NO2 is photolyzed. Different ratios of NO2/NOx acted differently on the ozone concentration. When NO2/NOx consisted of mostly NO the concentration of ozone decreased and when NO2/NOx consisted of mostly NO2 it increased. Different ratios did not affect the end concentration of the total NOx. When hydrocarbon compounds and CO was studied an increase produced more ozone and decrease the concentration of NOx. The result was the same when all the volatile organic compounds with CO and when only the non-methane volatile organic compounds was changed.}},
  author       = {{Reimer, Henrik}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Modeling of ozone and nitrogen oxides pollutions in urban air environments}},
  year         = {{2018}},
}