THERMODYNAMICS OF TOXIC AUTOMOTIVE EMISSIONS IN CITY AIR AND AIR PURIFICATION BY PLANTS

Abstract

Such an important ecological and geochemical problem as urban air pollution by toxic gas emissions from road transport was assessed by specific measurements of the air composition in Academmistechco of the city of Kviv. Thermodynamic analysis of the chemical reactions involving such toxic gases as carbon monoxide and nitrogen oxides emitted from transportation has been carried out. These toxic gases are preferentially released when the speed of automobiles decreases and the temperature and gas pressure in the engine decreases, and consequently the amount of oxygen for complete reaction becomes insufficient. That is, under these conditions, at low speeds of cars, other reactions take place in their engines with the formation of carbon oxides and nitrogen which are toxic substances for people. The highest pollution was found on the motorways and the adjacent sidewalks along them, and at the cross roads. These toxic gases are released and accumulated on the highways and paths, and can later migrate from them into the air of the city blocks in the process of diffusion. On all Kyiv streets, the maximum permissible concentration (MPC) of CO and nitrogen oxides is exceeded by 2-3 times, and on major highways such as Volodymyrska, Shevchenko and Khmelnytskyi streets this exceeding reaches 10 times. It was also concluded that trees and other plants play a significant role in air purification from the pollutants. Moreover, the trees seem to grow better than in the forest consuming toxic for people carbon and nitrogen oxides and even look better. Regarding the decisive actions to achieve clean air on the streets, besides greening electric engines should be used in cars more extensively like in trolleybuses and trams. This is closely connected with the development of nuclear energy production. From more general philosophic approach, the geochemical processes in the urban air polluted by automotive gaseous emissions can be viewed as dialectic between unity and diversity: on the one hand, the air pollution is harmful for people, on the other hand, it is valuable for vegetation. Such dialectic analysis of the urban air pollution processes favours extensive greening in cities, especially planting big trees, because besides transport, enterprises and factories also contaminate the environment.