Pollution of atmospheric air above the city highways

Abstract

The study is devoted to the estimation of pollution deposit caused by vehicles into the city total greenhouse gases emissions and to the forecast of the secondary air pollution with formaldehyde. The present study contains mathematic model which allows getting the estimation of vehicles emission in the total amount of polluted atmospheric air. The model consists of two interconnected parts: a dynamic and a kinetic one. The first part of the model is based on the Theory of Convective Jet and Thermals in the Atmosphere and allows to get the parameters of the contaminated air which is being formed over the highway. The Dynamic part of the model allows to get the total amount of hydrocarbons emission depending on the number of vehicles which is present at the same time on the highway. We also obtain the data on concentration of pollution and temperature increasing in the narrowest section of the thermal jet. The kinetic part of the model allows to determine the concentration of the secondary atmospheric air contamination with formaldehyde as a result of photochemical transformation of hydrocarbons which are the part of emission of internal combustion engine. The speed of the transformation reaction was determined by the Can't Hoff-Arrhenius deferential equation. The given mathematical model was tested with the help of the system of regular observation over the polluted atmospheric air in Kyiv city. The comparison of the estimated value of formaldehyde concentration and the observation data doesn't exceed 5 % above the maximum values. According to average monthly rates there is a false positive error (to + 20 % in the warmest months). Basing on the given model the calculator of concentration of pollution by vehicles was developed. This calculator allows to obtain rapidly the values of formaldehyde concentration, depending on air temperature, solar radiation and number of vehicles on the highway. The amount of hydrocarbon emission from the vehicles, according the suggested model, allows to estimate the deposit of vehicles into the total amount of greenhouse gases of the city. The obtained results could be useful in forming of ecological policy of the cities and in managerial decision making.