Air pollution as result of photooxidants (ozone) originated in the troposphere

Abstract

Ozone (O3) and peroxideacetyl-nitrate are the significant photooxidants. Tropospheric ozone, together with mixture of gases of nitrogen oxide NOX (N2O, NO, NO2), carbonhydrid (CH), SO2 and formaldehyde which are released from automobiles and industry, presents an aggressive mixture of harmful gases. Under the strong influence of ultraviolet radiation, tropospheric ozone is exceedingly aggressive both to flora and fauna as well is to protect the living world on the Earth. The presence of stratospheric ozone in the atmosphere is not only unable to compensate for the effects of the ozone layer thinning, but it itself brings new problems. Tropospheric ozone, together with CO2, is one of the 'greenhouse' gases, which means that it directly affects a climate. The presence of ozone in troposphere increases the oxidative capability of the atmosphere, and so the gases emitted from a combustion process (SO2 and nitrogen oxides) are oxidation to the most stable forms, increasing the acidivity of the atmosphere by the presence of long-living acid aerosols, which by dissolving in water drops, transform into strong acids (H2SO4 and HNO3 causing the occurrence of the so called acid rains. The increase of ozone contents in the troposphere is connected with the occurrence of episodes of photochemical smog in regional proportions, in the calm and sunny weather. The acts of protecting both one and the other kind of ozone are mutually dependent. By protecting the stratospheric ozone - the ozone layer, the emission of ultraviolet radiation which reaches the Earth is reduced, hence the quantity of tropospheric ozone as well, and all that together cannot be achieved if the emission of harmful gases from industry and traffic is not controlled. Problem of an photoxidants concentration increasing in the troposphere to be global in the next future.

Ozon i peroksiacetil-nitrat predstavljaju najznačajnije fotohemijske oksidanse. Troposferski ozon, zajedno sa gasovima oksida azota NOX (N2O, NO, NO2), ugljovodonika, SO2 i formaldehida koji se ispuštaju iz automobila i iz industrije, predstavlja agresivnu smesu štetnih gasova. Troposferski ozon je, pod snažnim dejstvom ultraljubičastog zračenja, izuzetno agresivan i za životinjski i biljni svet, njegovo prisustvo u atmosferi ne samo da ne može da kompenzuje posledice smanjivanja ozonskog omotača, već, sa svoje strane donosi nove probleme. Troposferski ozon je, zajedno sa SO2, jedan od gasova 'staklene bašte', što znači da direktno utiče na klimu. Prisustvo ozona u troposferi povećava oksidacionu sposobnost atmosfere, pa se emitovani gasovi iz procesa sagorevanja (SO2 i oksidi azota) oksiduju do najstabilnijih oblika, povišavajući kiselost atmosfere prisustvom dugoživećih kiselih aerosola, koji rastvaranjem u kapljicama vode prelaze u jake kiseline (H2SO4 i HNO3) što dovodi do pojave tzv. kiselih kiša. Povišavanje sadržaja ozona u troposferi vezano je za nastajanje epizoda fotohemijskog smoga u regionalnim razmerama, po tihom i sunčanom vremenu. Zaštite i jednog i drugog ozona međusobno su zavisne. Čuvanjem stratosferskog ozona - ozonskog omotača, smanjuje se emisija ultraljubičastog zračenja koje stiže do Zemlje, samim tim i količina troposferskog ozona, a to se opet sve zajedno, ne može postići ukoliko se u industriji i saobraćaju ne kontroliše emisija štetnih gasova. Uvećanje koncentracije fotohemijskih oksidanata će se pojaviti kao globalni problem u bliskoj budućnosti.