Our Environment

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Changes in the environment affect us and our activities change the environment around us.

Improvements in lifestyle have resulted in the accumulation of large amounts of waste materials.

Garbage contains following type of materials :

Biodegradable: Substances which can be decomposed by the action of micro-organisms are called biodegradable wastes. E.g., fruit and vegetable peels, cotton, jute, dung, paper, etc.

Non-biodegradable wastes: Substances which cannot be decomposed by the action of micro-organisms are called non-biodegradable wastes. E.g., plastic, polythenes, metals, synthetic fibres, radioactive wastes, pesticides etc.

Micro-organisms release enzymes which decompose the materials but these enzymes are specific in their action that’s why enzymes cannot decompose all the materials.

Some methods of waste disposal

1. Biogas plant: Biodegradable waste can be used in biogas plant to produce biogas and manure.
2. Sewage treatment plant: The drain water can be cleaned in sewage treatment plant before adding it to rivers.
3. Land fillings: The wastes are buried in low lying areas and are compacted by rolling with bulldozers.
4. Composting: Organic wastes are filled in a compost pit and covered with a layer of soil, after about three months garbage changes to manure.
5. Recycling: Non-biodegradable wastes are recycled to make new items.
6. Reuse: It is a conventional technique to use an item again e.g., newspaper for making envelops.

Ozone (O₃) is a molecule formed by three atoms of oxygen. While O₂, which we normally refer to as oxygen, is essential for all aerobic forms of life.

Ozone is a deadly poison.However, at the higher levels of the atmosphere, ozone performs an essential function. It shields the surface of the earth from ultraviolet (UV) radiation from the Sun. This radiation is highly damaging to organisms, for example, it is known to cause skin cancer in human beings.

Formation of Ozone layer:

Ozone at the higher levels of the atmosphere is a product of UV radiation acting on oxygen (O₂) molecule. The higher energy UV radiations split apart some molecular oxygen (O₂) into free oxygen (O) atoms.

O₂  + UV ----> O + O

These atoms then combine with the molecular oxygen to form ozone as shown

O₂ + O--> O₃ (ozone)

Depletion of the ozone layer:

The decrease in the thickness of ozone layer over Antarctica was first observed in 1985 and was termed as the ozone hole.

This decrease was linked to excessive use of synthetic chemicals like chlorofluorocarbons (CFCs) which are used in refrigerators, ACs, fire-extinguishers, aerosols sprays etc.

United Nations Environment Programme (UNEP) succeeded in forging an agreement to stop CFC production at 1986 levels (KYOTO PROTOCOL) by all countries.