Modelling of motor transport exhaust gas influence on the atmosphere

Abstract

Mobile pollutant sources, such as industry and energetics, are the basic sources of pollutant emission to the atmosphere in Lithuania. However, motor transport has the greatest share in the emission of mobile pollutant sources.The carried out investigation revealed that in Vilnius Žirmūnai district the highest concentration of pollutants is emitted during morning and afternoon rush hours when traffic is the heaviest. In 14 places of the streets in Žirmūnai three types of cars were counted (lights, medium, heavy) and with COPERT program maximal emissions of CO, NOx, CHx, SO2 were fixed. Using these data, numerical modelling of transfer processes of these pollutants was carried out. The research results indicate that the high amounts of emitted gaseous pollutants are recorded 1-2 m away from the driving part and 4–6 m away the amounts of the exhaust sharply go down. It has been set that concentration of CO, NOx, CHx, SO2 directly depend on motor transport‘s intensity. The amount of the substances goes evenly down receding from the driving part. In most cases maximum permitted concentration of these pollutants was recorded.

Pagrindiniai atmosferos taršos šaltiniai miestuose yra mobilus (automobiliu transportas), taip pat ir pramon s bei energetikos taršos šaltiniai. Automobiliu transporto išmetami teršalai duoda didžiausia emisija i aplinka. Tyrimais nustatyta, kad daugiausia teršalu yra išmetama rytinio ir vakarinio piko valandomis, kai automobiliu transporto eismo intensyvumas mieste yra pats didžiausias. Automobiliu transporto išmetalai yra ypac dideli intensyvaus eismo miesto gatv se ir 2–5 m atstumu nuo važiuojamosios kelio dangos, o esant 6–10 m atstumui ju kiekiai staigiai sumaž ja. Nustatyta, kad CO, NOx, CHx, SO2 koncentracijos tiesiogiai priklauso nuo automobiliu transporto eismo intensyvumo. Koncentracija tolygiai maž ja did jant atstumui nuo gatv s važiuojamosios dalies. Tyrimai atlikti Vilniaus mieste 14 Žirmunu gatviu vietu, kur skaiciuotas važiuojancio automobiliu transporto (lengvuju, vidutinio lengvumo, sunkiuju automobiliu) skaicius, pagal tai su COPERT programa nustatytos rytinio ir vakarinio piko valandomis vidutin s CO, CHx, NOx, SO2 koncentracijos. Naudojant jas atliktas dujiniu teršalu sklaidos Žirmunuose matematinis modeliavimas. Daugeliu atveju gautas CO, NOx, CHx didžiausios leistinosios koncentracijos (DLK) viršijimas.