Question

Which of the following affects the self-cleansing capacity of the river?
A.Aquatic organisms
B.Drawing of water for irrigation
C.Hydroelectricity generation
D.Pollution

Answer 1

Hint: Self-cleansing means to get rid of the waste material and pollutants present in any water body. This means the thing which affects the most increases and hinders the self-cleansing. It is of many types and many forms, it occurs due to various reasons.

Complete answer: Pollution is the correct option. Pollution is the harmful waste material produced in the environment due to various activities of the human being. Pollutants are not always man-made; sometimes it can be natural. Pollution is caused due to smoke produced by industries or factories. Types of pollution are water, land, air, soil and noise. Water pollution is the contamination due to human activities.
Washing clothes, throwing wrappers, dead bodies in the water, sewage water and discharge of industries are very much responsible for pollution. Water pollution is dangerous for aquatic animals, their life span is reducing as a result of this. Water bodies like lakes, rivers, seas and ponds are able in self-cleansing. But increasing waste makes it difficult for the rivers and lakes to continue the process. It is the reason for the suffering of aquatic and land animals and human beings too as it causes various diseases.

So the correct option is D. Pollution. It hinders the self-cleansing of the rivers.

Note: It is a less known fact that almost 70% of the industrial waste is dumped in the water bodies, 80% of domestic sewage is the cause of water pollution. Almost 6 billion pound waste is dumped in the water bodies every year. Many birds die due to waste pollutants in the environment annually.