DESCRIBE CAUSES AND METHODS OF CONTROLLING WATER POLLUTION. (20 MKS)

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It is the addition of substance into the water that may cause harm to organisms and are destructive to the ecosystem.

Causes of water pollution
  • Industrial effluents that may be toxic chemicals which kill the aquatic organisms; It can be controlled by treating the effluents before discharging them;
  • Hot water reduces the concentration of oxygen, killing the animals; It is controlled by placing hot water;
  • Oil spillage from oil tankers that reduces oxygen in water, reduces  penetration of light and clog feathers of marine birds; It can be controlled by regular servicing of oil tankers;

  • Domestic effluents; 
  • Untreated sewage that causes water borne diseases; It can be controlled by treating sewage before being discharged;
  • Detergents that causes eutrophication causing reduced oxygen concentration; It is controlled by banning phosphate based detergents;

  • Agricultural effluents;
  • Pesticides and herbicides that have heavy metal that they may accumulate along the food chain killing the higher animals; it is controlled by use of biological control pests;
  • Inorganic fertilizers that have nitrates and sulphates that causes eutrophication; is controlled by use of organic fertilizers/ controlling soil erosion;
  • Silting due to soil erosion reduces penetration of light to the plants and clog respiratory surfaces of animals; it is controlled by proper farming methods;
 (20 MKS)

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