Our Environment
Substances that are broken down by biological processes are said to be biodegradable.
Substances that are not broken down in this manner are said to be non-biodegradable. These substances may be inert and simply persist in the environment for a long time or may harm the various members of the eco-system.
ECO-SYSTEM — WHAT ARE ITS COMPONENTS?
An ecosystem consists of biotic components comprising living organisms and abiotic components comprising physical factors like temperature, rainfall, wind, soil and mineral.
All green plants and certain bluegreen algae which can produce food by photosynthesis are called the producers.
These organisms which consume the food produced, either directly from producers or indirectly by feeding on other consumers are the consumers.
Consumers can be classed variously as herbivores, carnivores, omnivores and parasites.
energy flow diagram
TOP CARNIVORES
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CARNIVORES
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HERVIBORES
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PRODUCERS
^
SUNLIGHT
chemicals are either washed down into the soil or into the water bodies.
From the soil, these are absorbed by the plants along with water and minerals, and from the water bodies these are taken up by aquatic plants and animals.
This is one of the ways in which they enter the food chain.
As these chemicals are not degradable, these get accumulated progressively at each trophic level. As human beings occupy the top level in any food chain, the maximum concentration of these chemicals get accumulated in our bodies. This phenomenon is known as biological magnification.
This is the reason why our food grains such as wheat and rice, vegetables and fruits, and even meat, contain varying amounts of pesticide residues. They cannot always be removed by washing or other means
HOW DO OUR ACTIVITIES AFFECT THE ENVIRONMENT?
Ozone Layer and How it is Getting Depleted 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.
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 moleculer oxygen (O2) into free oxygen (O) atoms.
The amount of ozone in the atmosphere began to drop sharply in the 1980s.
This decrease has been linked to synthetic chemicals like chlorofluorocarbons (CFCs) which are used as refrigerants and in fire extinguishers.
In 1987, the United Nations Environment Programme (UNEP) succeeded in forging an agreement to freeze CFC production at 1986 level
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