An undesirable biological or chemical element present in water that negatively affects living organisms is called water pollution.Source of Water Pollution
i) Contamination of the pointing source: if the pollution comes from one unidentified source then it is known as a point source. For example, municipal resources, industrial resources etc.
ii) Non-point source pollution: if the pollution comes from a random or scattered source then it is known as a non-point source. For example, construction site, agricultural area, Acid rain, animal waste etc.
Causes and consequences of water pollution
a) Pathogens: micro-organism including bacteria, viruses, protozoa, if present in drinking water cause disease. For example,
b) Oxygen-depleting waste: aquatic organisms are degraded by micro-organisms in the water that need oxygen. If a large number of organisms are present in polluted water, a large amount of oxygen is needed by the microorganism to reduce waste. Therefore the oxygen content in the water is reduced. The amount of oxygen consumed by the microorganism is called the Biological Oxygen Demand (BOD). A high level of BOC means a large amount of waste is present in the water.
c) Water-soluble chemicals: nutrients such as lead, mercury, cadmium, arsenic adversely affect humans and animals. For example, cadmium causes Itai-Itai disease, mercury causes Minamata disease.
d) Solid solidification: if the solid suspension is present in the body of water, then the water changes and therefore sunlight should not reach the tree and aquatic animals that interfere with the aquatic life.
Control measure to prevent water pollution
i) Industrial sewage and household waste must be treated before disposal.
ii) Reuse of wastewater by wastewater treatment.
iii) Public Awareness Program.
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