Effects of UV rays:
- UV radiations shorter than UV-B are almost completely absorbed by Earth’s atmosphere, if the ozone layer is intact.
- DNA and proteins of living organisms are damaged by UV rays as they potentially absorb it.
- The high energy of UV rays breaks the chemical bond in these molecules.
- UV – B damages DNA and mutation may occur.
- It causes ageing of skin.
- Damage skin cells and causes skin cancers.
- In human eye cornea absorb UV – B radiation and high dose of UV – B causes inflammation of cornea called snow-blindness, cataract etc.
- Such exposes may damage cornea.
Prevention:
- Montreal Protocol was signed at Montreal (Canada) in 1987 to control emission of ozone depleting substances.
- Many efforts are being made to reduce emission of ozone depleting substances.
DEGRADATION BY IMPROPER RESOURCE UTILIZATION AND MAINTENANCE:
Soil erosion
- The removal of top fertile layer due to human activities
Reasons: -
- Over cultivation
- Unrestricted grazing
- Deforestation
- Poor irrigation practices
Water logging and soil salinity:
- Irrigation with proper drainage, leads to water lodging in the soil.
- Draws salt to the surface of the soil.
- The salt starts collecting at the roots of the plants.
- The salt damages the roots and crop productions.
Deforestation:
- Conversion of forested areas to non-forested one.
How deforestation does occurs:
- Slash and burn agriculture/jhum cultivation
- Farmers cut down the trees of the forest and burn the plant remains.
- Ash is used as fertilizer and land is used for farming or cattle grazing
- Later, Land is left uncultivated for several years for replenishment of minerals
Effects of deforestation
- Leads to global warming due to excess carbon-dioxide
- Loss of biodiversity
- Damage to hydrological cycle
- Leads to soil erosion
- Desertification of land
Reforestation
- Restoring forest that was existing earlier E.g. Observing Van-Mahotsavas
- It also occurs naturally
- Aforestation Developing a forest in a new area where no such forest existed in that area.
A case study of people‘s participation in forest conservation
- A king of Jodhpur wanted to arrange wood for his new palace in 1731.
- Few Bishnois hugged the trees and asked to cut them first rather than cutting trees.
- 365 persons lost their lives in this act
- A small temple is now present there in remembrance of this act
- Amrita Devi Bishnois Wild Life Protection Award is instituted for individuals of rural areas who take keen interest in protecting wild life.
- Chipko movement
- It was started by local women of Garhwali; they hugged the trees to protect them from the axes of contractors.
- Joint forest management (jfm)
- Strategy Government of India in 1980
- Local communities worked with the government to save the forest.
- Communities get forest products for encouragement.
CPCB: Central Pollution Control Board
BOD: Biological Oxygen Demand
CNG: Compressed Natural Gas
FOAM: Friends of Arcata Marsh
JFM: Joint Forest Management.
CBSE Biology (Chapter Wise) Class XII ( By Mr. Hare Krushna Giri )
Email Id : [email protected]
