2007-9-10

Text:

Ozone in atmospheric stratosphere absorbs a large volume of solar emitted ultraviolet radiation harmful to human and fauna and flora species (also known as UV-B), providing the earth with a screen from harmful ultraviolet radiation. Damages to ozonosphere increased ultraviolet radiation to the ground and also produced harm to all creatures on the earth.

Phenomena:

In 1984, British scientists first discovered an ozone hole in the air over South Pole, and in 1985, US 'Windcloud 7'meteorological satellite detected this 'hole' having an area equal to US territory and a depth similar to the height of Everest (See Picture 1).

(Note to Picture 1: the ozone hole in the air over the South Pole photographed by NASA in 2000 is just like a huge green water drop.)

Origins of ozone hole: Scientists have various views on damages to ozonosphere. Natural causes: relating to volcano eruption, forest fire and low temperature in polar region; affected by natural sunspot activity cycle. Human reasons: majority scientists believe that over use of CFCs type materials is the main cause of damaged ozonosphere. (Picture 2: Atmosphere Ozone Decrease Mechanism Sketch Map)

(Picture 2: Atmosphere Ozone Decrease Mechanism. Note: originally, there is a balance in atmospheric stratosphere 10,000-50,000 from the earth surface together with the ozonosphere functioning in absorbing ultraviolet radiation and protecting creatures in earth from harm by over ultraviolet radiation. The reaction of nitrogen oxides, chlorine, bromine and other active groups discharged to the air with O3 breaks the chemical balance among 0.02and O3,damaging the ozonosphere even producing zoon hole.)

Related terms: Ozone-ozone(O3)is the allotropic modification of oxygen; ozone content is very few in the atmosphere, but its density change will have great influence on human health and climate.

Determination of ozone-total quantity of ozone is determined by terrestrial sensor or satellite-carried sensor; the vertical distribution of ozone must be measured by terrestrial detecting technique, star detecting technique, mar detecting technique and satellite technique. For analysis on long-term global ozone variation trend, satellite detection is becoming more and more important.

Ozone-exists in earth atmosphere at least 10km from the earth surface with variable density depending on altitude and shows the highest density in atmospheric stratosphere(20-25km from the ground.)

Ozone hole-decreasing ozone density produces ozone hole. Discovered by scientists, that ozone hole is normally appear in the South Pole in spring season, i.e., ozone hole appear in September each year when ozone density is decreasing and disappears in mid of November. The normal ozone density is 300Dobson, while ozone density in ozone hole is 110-6Dobson.

(Picture 3: Ozone Hole Variation. Note: RED and GREEN are holes. The left was photographed in September 2001, and the right was photographed in Sept. 2002)

(Note to Picture 4: Further Increase of South Pole Ozone Hole in 2006)

Impacts:

Give adverse impacts to human health, increase human being's chances of direct exposure to UV-B radiation, damage human being's immunity from diseases, and increase incidence rate of skin cancer and cataract;

Agricultural crops are most sensitive to ultraviolet rays and their seeds can easily be affected, more importantly, agricultural crops are easily damaged by weeds and plant diseases and insect pests;

Increased UV-B radiation will directly result in damages to import life-forms in aquatic plant chain;

Increased UV-B radiation will further worsen the smoke in urban areas.

Countermeasures: Ozonosphere loss/damage is a global atmospheric environment issue attracting wide public concern. The best way to treat this issue is to stop the use of CFCS, and control the emission of CFCS by:

Improve equipment for increasing their utilization and decreasing operational losses;

Adopt recycling technologies to decrease CFCS discharge;

Improve CFCS products;

Replace CFCS products with non CFCS products.