Stratospheric layer

Ozone is main component in many oxidation processes assembled imder the term ozonation processes. In these processes ozone is applied either alone (O3 process) or with the addition of oxidant, e.g. H2O2 (O3/H2O2 process), UV radiation (explained in above subchapter), catalyst, activated carbon, ultrasoimd etc. Ozone is inorganic molecule constituted by three atoms of oxygen. It is present in nature in upper atmosphere in the form of stratospheric layer aroimd the earth, and it is formed by the photolysis of diatomic oxygen and further recombination of atomic and diatomic oxygen, shown by equations (25) and (26) [35] ... 

Further extension of in situ ion composition measurements into the even denser stratospheric layer required greatly improved mass spectro-metric techniques and became feasible only in 1977 using balloon-borne mass spectrometers. The first negative ion composition measurements in... 

However, some scientists believe that the young Earth was too inhospitable a place for life to have developed on its surface at all lacking O2, the atmosphere would also have lacked its present-day stratospheric layer of ozone (O3), which screens large quantities of harmful ultraviolet radiation from the surface. They believe that a more likely environment for abiogenesis (life from prelife) was in the vicinity of deep-sea vents, holes in the crust under the ocean from which hot, mineral-laden water flows. 

Ozone layer The stratospheric layer of gaseous ozone (O3) that protects life on Earth by filtering out most of the harmful ultraviolet radiation emitted by the Sun... 

Stratosphere Layer of the atmosphere above the troposphere, up to 50 km from the surface of the earth. 

Ozone Triatomic form of oxygen produced when diatomic oxygen is exposed to ultraviolent radiation (its presence in a stratospheric layer protects life-forms from harmfrd solar radiation). 

In the last two decades of the past century, the presence in the atmosphere of ozone-depleting substances (CFCs, HCFCs, halons, carbon tetrachloride, etc.) has been reducing the ozone concentration in the stratosphere over high and mid-latitudes of both hemispheres. Ozone concentration in the atmosphere is very low (about 3 parts in 10 millions), and that of the total ozone column is equivalent to that of 3 mm at standard temperature and pressure. Nevertheless, its optical density is about 45 at the absorption maximum around 255 nm, about 13 at 280 nm, and goes to 0 at 320 run. Therefore, the stratospheric layer, which contains approximately 90% of the total ozone, has the function of a protective filter for the Earth s surface, fully cutting off solar radiation under 280 nm and greatly reducing UV-B radiation (280 to 315 nm). 

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