Describe causes and methods of controlling water pollution

K.C.S.E Biology Q & A - MODEL 2007PP2QN08

Describe causes and methods of controlling water pollution

answers

• It is addition of substance into water that may cause harm to organisms and are disruptive to ecosystem.
• The causes of water pollution include:
• Industrial effluents that may be toxic chemicals which may kill the aquatic organisms. It can be controlled by treating the effluents before discharging them.
• Hot water that reduces concentration of oxygen killing the animals. It is controlled by placing high penalties on factories discharging hot water.
• Oil spillage from oil tankers that reduces oxygen in water, penetration of light intensity and clog feathers of marine birds. It can be controlled by regular servicing of oil tankers.
• Domestic effluents that include:
• Untreated sewerage that causes water borne diseases. It can be controlled by treating sewerage before being discharged.
• Detergents that cause eutrophication causing reduced oxygen concentration. It is controlled by banning phosphate based detergents.
• Agricultural effluents that include:
• Pesticides and herbicides that have heavy metals that they may cumulates along the food chain killing the higher animals. It is controlled by use of biological control of pests. 
• Inorganic fertilizers that have nitrates and sulphates that cause eutrophication is controlled by use of organic fertilizers.
• Silting due to soil erosion reduces penetration of light to the plants and clog respiratory surfaces of animals. It is controlled by proper methods of soil erosion and proper farming methods.