Hospital wastes:
- Hospitals generate hazardous wastes that contain disinfectants and other harmful chemicals, and also pathogenic organisms.
- The use of incinerators is crucial to disposal of hospital wastes.
Electronic wastes (e-wastes):
- Irreparable computers and other electronic goods are known as electronic wastes (e-wastes).
- E- Wastes are buried in landfills or incinerated.
- Metals like copper, iron, silicon, nickel and gold are recovered during recycling process of e-wastes.
- Manual recycling process exposes workers to toxic substances present in e-wastes.
- Recycling is the only solution for the treatment of e-wastes.
AGRO-CHEMICAL AND THEIR EFFECTS:
- Use of inorganic fertilizers and pesticides has increased manifold for enhancing crop production.
- Pesticides, herbicides, fungicides etc, are being increasingly used.
- These are toxic to non-target organisms that are important components of the soil ecosystem?
- Increasing amounts of artificial fertilizers causes eutrophication.
Case study of organic farming: (Ramesh Chandra Dagar of Sonipat)
- Integrated organic farming is a cyclical, zero waste procedure, where waste products from one process are cycled in as nutrients for other processes.
- Maximum utilization of resource and increase the efficiency of production.
- He includes bee-keeping, diary management, water harvesting, composting and agriculture in a chain of processes, which support each other and allow an extremely economical and sustainable venture.
Advantages:
- There is no need of use of chemical fertilizers for crops
- Cattle excreta are used as manure.
- Crop waste used to create compost, which can be used as a natural fertilizer or can be used to generate natural gas for energy need.
RADIOACTIVE WASTES:
- Nuclear energy was hailed as a non-polluting way for generating electricity.
- Later on it was realized that it has two very serious inherent problem:-
- Accidental leakage, as occurred in Three Mile Island and Chernobyl.
- Safe disposal of radioactive wastes.
- Radiation from radioactive waste causes mutation at very high rate.
- High dose of nuclear radiation is lethal, but lower doses create genetic disorders and also cause cancer.
Disposal of nuclear wastes:
- Storage of nuclear waste, after sufficient pre-treatment, should be done in suitably shielded containers buried within the rocks about 500 m deep below the earth’s surface.
GREEN HOUSE EFFECT AND GLOBAL WARMING:
- The term “Greenhouse effect” has been derived from a phenomenon that occurs in greenhouse.
- In a greenhouse the glass panel lets the light in, but does not allow heat to escape. Therefore the greenhouse warms up, very much like inside a car that has been parked in the sun for a few hours.
- The greenhouse effect is a naturally occurring phenomenon that is responsible for heating of Earth’s surface and atmosphere.
- Without greenhouse effect the average temperature at surface of earth would have been a chilly -18o C rather than the present average of 15o C.
- Clouds and gases reflect about one-fourth of the incoming solar radiation and absorb some of it but half of incoming solar radiation falls on Earth’s surface heating it, while a small portion is reflected back.
- Earth’s surface re-emits heat in the form of infrared radiation but some part of this does not escape into space because of atmospheric gases (e.g. carbon dioxide, methane etc).
- The molecule of these gases radiate heat energy and a major part of which again comes to Earth’s surface, thus heating it up once again.
- Carbon dioxide and methane – are commonly called as greenhouse gases because they are responsible for greenhouse effect.
- Increase in the level of greenhouse gases has led to considerable heating of Earth leading to global warming or enhanced green house effect.
- During the past century, the temperature of Earth has increased by 0.6o C.
Effect of global warming:
- Deleterious changes in the environment and resulting in odd climatic changes (e.g. El Nino effect).
- Increased melting of polar ice caps as well as of other places like the Himalayan snow caps.
- Rise in sea level that can submerge many coastal areas.
Control of global warming:
- Reduce use of fossil fuel.
- Improving efficiency of energy usage.
- Reducing deforestation.
- Promoting aforestation programme.
- Slowing down growth of human population.
- International initiative to be taken to reduce emission of green house gases.
OZONE DEPLETION IN THE STRATOSPHERE:
- ‘Bad’ ozone formed in the lower atmosphere (troposphere) that harms plants and animals.
- There is ‘good’ ozone also; this ozone is found in the upper part of the atmosphere called stratosphere, and it acts as a shield absorbing ultraviolet radiation from the sun.
- The thickness of ozone layer is measured in terms of Dobson units (DU)
- Ozone (O3) gas is continuously formed by the action of UV rays on molecular oxygen, and also degraded into molecular oxygen in the stratosphere.
- There should be proper balance of formation and degradation of ozone.
Ozone depletion:
- Balance of ozone in stratosphere is disrupted due to enhancement of ozone degradation by chlorofluorocarbons (CFCs).
- CFCs find wide use as refrigerants.
- CFCs discharged in the lower part of atmosphere move upward and reach stratosphere.
- In stratosphere, UV rays acts on CFCs and release active Cl atoms.
- Cl degrades ozone releasing molecular oxygen.
- Cl acts as catalysts and not consumed during reaction.
- Whatever CFCs are added to the stratosphere, they have permanent and continuing affects one Ozone levels.
- The depletion is marked particularly over the Antarctic region. This has resulted in formation of a large area of thinned ozone layer, commonly called as the ozone hole.
CBSE Biology (Chapter Wise) Class XII ( By Mr. Hare Krushna Giri )
Email Id : [email protected]
