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In this chapter, we will study about the harmful changes taking place in our surroundings and their effects on our lives. We can survive for some time without food, but we cannot survive even for a few minutes without air. This simple fact tells us how important clean air is to us. You already know that air consists of a mixture of gases.
Pollution is any undesirable change in physical, chemical or biological characteristics of air, land, water or soil. Agents that bring about such an undesirable change are called as pollutants.
Pollution can be classified into (i) air pollution, (ii) water pollution, (iii) land pollution and (iv) noise pollution. Indiscriminate use of water by increasing population and industrial expansion has led degradation of the quality of water considerably. Surface water available from rivers, canals, lakes, etc. is never pure.
From reviewing fundamental operations to exploring basic concept, the 18: Pollution of Air and Water Chapter lays the groundwork for the rigorous mathematical reasoning and problem-solving skills that students will develop throughout the course.
Class 9 Environmental Studies NCERT Book Pdf. We have provided below the latest CBSE NCERT Book for Class 9 Environmental Studies which can be downloaded by you for free. These free subject-wise NCERT textbook have been designed based on the latest CBSE Syllabus issued for current academic year.
Pollutants that enter water have the ability to spread to distant places especially in the marine ecosystem. From an ecological perspective pollutants can be classified as follows: Degradable or non-persistent pollutants: These can be rapidly broken down by natural pro-cesses. Eg: domestic sewage, discarded veg-etables, etc.
Water pollution is defined as the presence of foreign substances or impurities (organic, inorganic, biological or radiological) in water, thus degrading its quality and rendering it toxic to humans or the environment. According to Water pollution act (1974) contamination of water or such alteration of the physical,
