CYCLING OF MATERIALS (BIOGEOCHEMICAL CYCLE):
Non-living components of an ecosystem, move through the environment in a series of step called a cycle. Oxygen, carbon dioxide, nitrogen and water are the important non-living materials that are always needed by every ecosystem. These are being continuously driven in a circular path and are thus, continuously recycled to be used again and again.
Materials are recycled in an ecosystem but energy cannot be recycled.
Carbon is an essential constituent of organism. It is needed for the formation of proteins, carbohydrates and fats. Carbon comes from carbon dioxide is utilized by plants in photosynthesis. Carbon in this form passes into a food chain. It is returned to air by combustion due to burning of wood and other organic fuel like coal, petrol and gas.
Two life processes the respiration and photosynthesis help a lot to run the carbon-Oxygen cycle. Respiration consumes oxygen for the combustion of food for release of energy and carbondioxide is released into the atmosphere. Photosynthesis on the other hand consumes carbon dioxide and releases oxygen. In this way, the proportion of CO2 in the atmosphere is kept fairly maintained.
Graphic Diagram of Carbon Cycle
Water Cycle (Hydrological cycle):
The water is recycled and used again and again. This water cycle is powered by the heat of the sun. The sun rays cause water to evaporates from oceans, rivers, lakes and ice caps of the mountains vaporized water rise into the atmosphere, this process is called evaporation. When temperature of air cools, water vapours condense and form tiny drops of water and fall on earth as rain and snow, this process is called precipitation. Some water run off into oceans, river and lakes etc. the rest seeps into the soil. Some of this ground water is absorbed by the roots of the plants.
The plants return this water to the air through transpiration. The animals returned this water to the environment as they urinate and perspire. In this way water cycle continues in nature.