When do we use the term water pollution. Give examples.
The term water pollution is used when there is :
(i) Addition of undesirable substances to water bodies. For example, addition of industrial wastes containing poisonous salts like mercury salts, pesticides, insecticides, etc. Addition of disease causing organisms, like cholera causing bacteria through sewage.
(ii) The removal of desirable substances from water bodies. For example, depletion of dissolved oxygen and nutrients which adversely affects aquatic animals and plants.
(iii) A change in temperature of water in water bodies which adversely affects the organisms living in the water bodies.
List water pollutants.
What are the causes of soil erosion?
What are the methods of preventing or reducing soil erosion.
List any three human activities which would lead to an increase in the carbon dioxide content of air.
