Causes of Greenhouse effect
Effects of Green House Gases
(1) CO2 fertilization effect
Increase in atmospheric concentration of CO2 increases productivity of C3 plants and decreases rate of transpiration due to partial stoitiatal closure.
(2) Possible Effects of Global Warming
• Increasing of global temperature and more extreme weather conditions.
• Warming of troposphere and cooling of stratosphere and thermosphere.
• Rising of sea level, changes in rainfall pattern.
• Global warming will push tropics into temperate areas and temperate areas towards pole (shifting of climatic zones) and higher altitudes in mountains resulting into changed species distribution.For More Biology Doubts check out our biology doubts section.
(3) Ozone Depletions
• Ozone layer is present in stratosphere at altitude of 23-25 km (conc. 0.3 ppm) and act as shield
• against UV radiation.
• Largehole has appeared in ozone shield over Antarctica and smaller one over North pole.
• (Discovered by Farman 1985).
• Ozone is commonly called as chemical weed.
• CFC, CH4, CC14, halons and N2O causes destruction of O3 (ODS : ozone depleting substance).
• CFCS are most damaging. They release Cl atom in stratosphere which destroy O3.
• Thinning of the ozone-layer results in an increase in the UV-B radiation.
• Now a days CFC are being replaced by hydro fluoro carbons (HFCs) and hydrochloro fluoro carbons (HClFCs).
• Benzpyrene: It is a carcinogen.
• Peroxy-Acyl Nitrates: Major constituents of air pollution e.g., PAN, PPN and PBN.
• Chemical oxygen demand (COD): “An indicator of water or effluent quality which measures O2 demand by using K2Cr2O7 as oxidizing agent. The BOD: COD ratio is fairly constant for a given effluent.
Bhopal Gas Disaster
Date: Dec. 2, 1984
Dec. 2 is observed as the national pollution prevention day.
Killed over 2000 and injured over 250,000 persons.
• Grey snow: Occurred in Norway due to soot from industrial Ruhr area of Germany.
• Gulf war: Fire from oil wells changed the colour of clouds and rain in north India.
• Ganga action plan was started in 1985 to control pollution in Ganges.
• Hiroshima day = August 6 Nagasaki day = August 9
• Ozone day = September 16
• Sewage contamination of water is indicated by coli.
• Deposition of cotton fibres in lungs causes byssinosis and pneumoconiosis.
• Super bug (oil cleaning bacteria) Pseudomonas putida degrades oil spills. It is a genetically engineered microbe developed by Dr. A.M. Chakraborty.
• Burning of plastics results in production of polychlorinated biphenyls.
• Vienna Convention 1985
• Montreal Protocol 1987 (To protect O3 layer and phasing out ODS)
• Earth Summit 1992 (UNCED): To reduce green house gases
• Kyoto Protocol 1997 (To mitigate climatic changes, reduce green house emission)