Water Pollution -

 Water is the most important factor for human existence on earth, it is because of water that the earth is called the 'blue planet'.  About three-quarters of the earth's surface is covered by water.  Many economic factors depend not only on the survival of all living things but also on water resources.  Water is needed for agricultural production, industrial production and to meet various human needs.  In the current scenario, water pollution and water scarcity are two of the most important resources facing this precious resource.  Increasing industrialization, colonization and population growth are depleting water resources. 

 Definition:  Changes in the physical, chemical and biological properties of water have adverse effects on aquatic life and other organisms, including humans. This is called 'water pollution'.

 Sources and types of water pollution:

 Water is polluted through various sources due to changing human lifestyles.Increasing pollution causes changes in the natural properties of water.  Domestic sewage, contaminated water from industrial estates, hot water from thermal power projects, oil spills, oil spills caused by accidents.  The main sources of water pollution are ballast boats used in ships. 

 Considering the following factors, different types of water pollution are as follows: 

1) Origin of Pollution

 2) Source of Pollution

 3) Nature of Pollution

 4) Origin and Storage Places

 Depending on the source of water pollution, it can be classified as central source and composite source.  Pollution from central sources can be easily identified as it is caused by a specific source.  E.g.  A pipe that discharges sewage, so that such pollution can be properly remedied.  Composite pollution, on the other hand, is more difficult to control as it comes from more than one scattered source.  E.g.  Sewage from farms, as well as contaminated water from industrial estates, etc.  The combination of different types of pollutants in composite pollution is more intense considering the overall pollution of the center.  Water pollution can be studied according to the changing nature or properties of water.  Such as physical pollution caused by changes in the natural properties of water, chemical pollution, biological pollution, etc.  Similarly, water pollution can be classified as surface water and groundwater pollution according to the source and location of water.  Surface water pollution includes river, pond, lake, creek or marine pollution.  Groundwater pollution includes water from wells, boreholes.

Consequences of Water Pollution -

 1) Domestic sewage contains many pathogenic bacteria and viruses.  Unclean water causes water borne diseases like cholera, typhoid, polio, diarrhea, etc.  

2) Mercury, nickel, zinc, etc., fractions of inert metals, fractions of various pesticides, as well as many harmful chemicals endanger life.  Mayuri and cadmium can cause diseases like 'Minamata' and 'Etai-Etai' respectively.  The entry of chemical pesticides into the food chain leads to the accumulation of insoluble and harmful substances in the food chain and in the food web.

  3) Due to mixing of phosphate and nitrate rich agricultural chemicals used in agriculture in nearby water bodies, weeds like water hyacinth grow excessively.  This is called 'Eutrophication' of water storage.  This process reduces the amount of oxygen dissolved in the water.  Suffocation leads to betrayal of aquatic animals.