NCERT 10th Class Science Chapter Our Environment
The physical and biological world we-live in is called our environment. It has the following three important parts :
1. Living organisms 2. Physical surroundings 3. Meteorological factors (or climatic factors).
• The living organisms which constitute environment are plants; animals, human beings and
• The physical surroundings, which make up the environment are land, water bodies and air.
• The meteorological factor or climatic factors, which form a part of our environment, are sunlight, temperature, rainfall, humidity,
In this chapter we are going to learn about interaction of various factors of the environment and effect of human activities affecting various biogeochemical cycles or environment.
Effect of human activity is an important factor which causes difference in the environment of different places. Through overuse, misuse and mismanagement of natural resources to fulfil his needs, man has done great damage to the environment himself. Various environment problems have arisen as a result of pollution, increasing population and coming up of advanced science and technology.
There is crowding, very less number of trees, large number of factories, which emit black smoke and large number of motor vehicles which emit poisonous gases. Moreover, due to large population there is lot of garbage, which is thrown indiscriminately on roads and other common places. These uncontrolled human activities not only pollute the city environment like soil, air and water but also harm the living organisms that are so essential for our survival. All these activities lead to ecological imbalance.
POLLUTION AND POLLUTANTS
With the increase in human population and advancement in technology waste materials have multiplied in quantity as well as quality. Contamination of environment with these waste material is called pollution. Not only the wastes but certain useful materials like fertilizers may also contaminate the environment. Thus, pollution may be defined as a change in the physical, chemical or biological aspects of environment which make it harmful for living organisms. Materials or agents which cause pollution of the environment are termed as pollutants e.g., smoke from vehicles, industries, sewage, various radioactive substances.
Pollutants are categorized into two types.
(a) Biodegradable pollutants (b) Non-biodegradable pollutants
Biodegradable pollutants can be quickly degraded by natural means i.e., by the action of various micro-organisms e.g. , sewage, paper, wool, bones and wood.