1. The Breath of Life: Air
Air is a mixture of gases indispensable for life. Air movements (winds) are caused by unequal
heating of earth's surface. Air pollution happens when harmful substances increase in
the atmosphere.
2. Water: A Wonder Liquid
Necessary for all cellular processes. Water pollution involves adding unwanted
substances or removing desired ones (oxygen) from water bodies.
3. Biogeochemical Cycles
- Water Cycle: Constant movement of water between earth and atmosphere.
- Nitrogen Cycle: Conversion of atmospheric nitrogen into forms usable by
plants (Nitrogen fixation).
- Carbon Cycle: Movement of carbon through photosynthesis, respiration,
and fossil fuels.
- Oxygen Cycle: Maintains atmospheric oxygen levels.
4. Greenhouse Effect and Ozone Layer
Greenhouse effect leads to global warming. The Ozone Layer protects us from
harmful UV radiations and is being depleted by CFCs.