تهتك طبقة الأوزون وأثره على البيئة

• Main Authors: بوران متوكل أحمد الإمام, عبد الله خيار عبد الله, اشراف ،
• Format: Thesis
• Language: unknown
• Published: جامعة افريقيا العالمية 2008
• Subjects: طبقة الاوزون; البيئة; Antarctic; Freed; The Antarctic; Antarc*
• Online Access: http://dspace.iua.edu.sd/handle/123456789/7216

Abstract The Ozone depletion is a slow and steady decline of Ozone in Earth's stratosphere (approximately 4% per decade) and the ozone hole is a much larger decrease in stratospheric ozone over Earth's polar regions during the spring season (over 50% of the lower stratospheric ozone is destroyed during the Antarctic spring) . Ozone depletion and ozone hole became an international problem that needs global effort to reduce their damaging effect. Ozone layer is a layer in the atmosphere that contains relatively high ozone concentration. Ozone layer protects the earth from the harmful Ultra-Violet Radiation (UV) that is not screened by any other atmospheric component. Ozone (O3) which is a colorless gas is present naturally in the atmosphere. About 90% of the ozone lies within the stratosphere-ozone layer – which always thought of as good ozone because it shields the earth from the harmful UV-B radiation which causes eye cataracts, skin cancer, immune system suppression, decrease in plant productivity and crop yield. The small percentage of the ozone which lies within troposphere is always thought of as bad ozone because when human breathe it, it cause asthmas, lung disease and different kinds of allergies. Ozone is created and destroyed naturally keeping its balance, but when man-made ozone depleting compounds (ODCs) reached a high level, that balance is lost and hence the ozone layer gets thinner, i.e., depleted. The ODCs are mostly chlorofluorocarbons و (CFCs), hydro chlorofluorocarbons (HCFCs), methyl chloroform (CH3 CCl3), carbon tetrachloride (CCl4), and halons. The ODCs are chemical substances that are used in refrigerators, air condition systems, aerosol cans…….etc. These compounds (mostly) contain chlorine (Cl) which when get freed, from the CFCs, by the action of UV, it attacks the ozone molecule (O3) and splits it into oxygen and chlorine monoxide, i.e., ozone destruction. In this investigation, thorough reviews of the ozone layer and the ozone depleting compounds have been given. The effect of ozone ...