WATER POLLUTION

Water pollution is any change in water quality that can harm living organisms or make the water unfit for human uses such as irrigation and recreation. It usually involves contamination by one or more chemicals or excessive heat (thermal pollution). 

Sources:

Water pollution can come from a single (point)source, or from a larger, more dispersed (nonpoint) source. 

Point sources discharge pollutants into bodies of surface water at specific locations through drain pipes, ditches, or sewer lines. Examples include factories, sewage treatment plants (which remove some, but not all, pollutants), underground mines, and oil tankers. Because point sources are located at specific places, they are fairly easy to identify, monitor, and regulate. Most of the world’s more-developed countries have laws that help control point-source discharges of harmful chemicals into aquatic systems. In most of the less-developed countries, there is little control of such discharges.

Nonpoint sources are broad and diffuse areas, rather than points, from which pollutants enter bodies of surface water or air. Examples include runoff of chemicals and sediments from cropland, livestock feedlots, logged forests, urban streets, parking lots, lawns, and golf courses. We have made little progress in controlling water pollution from nonpoint sources because of the difficulty and expense of identifying and controlling discharges from so many diffuse sources.

Major Water Pollutants and its Sources:

  • Infectious agents (pathogens) - Human and animal wastes.
  • Oxygen demanding wastes - Sewage, animal feedlots, paper mills.
  • Plant nutrients Nitrates - Sewage, animal wastes, inorganic fertilizers.
  • Organic chemicals - Industry, farms, households, mining sites, runoff from streets and parking lots.
  • Inorganic chemicals - Industry, households, mining sites, runoff from streets and parking lots.
  • Heavy metals - Unlined landfills, household chemicals, industrial discharges.
Common Diseases Transmitted to Humans through Contaminated Drinking Water:

  • Typhoid fever
  • Cholera
  • Bacterial dysentery
  • Enteritis
  • Infectious hepatitis
  • Poliomyelitis
  • Amoebic dysentery
  • Giardiasis
  • Cryptosporidium
  • Schistosomiasis
  • Ancylostomiasis


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