Eutrophication: Process & Control Measures

• The process of nutrient enrichment of water and consequent loss of species diversity is called eutrophication.
• Water polluted with inorganic fertilizers containing nitrates and phosphates or containing organic wastes causes eutrophication in water bodies.
• The Decomposition of organic wastes also increases nutrients in the water and causes eutrophication.
• During eutrophication, there is a luxuriant growth of algae, particularly blue-green in water. These form floating scums and water blooms.
• The algae use oxygen at night and may deoxygenate the water enough to kill the fish and other animals.
• The algal mat at the water surface may block light to the submerged plant.
• The algal species quickly complete their life cycle and die thereby adding a lot of dead organic matter, and feed the oxygen-consuming bacteria.

• They may be pushed on the shore by the wind and decompose, releasing foul gases, such as hydrogen sulfide.
• Silt and decaying matter may accumulate and finally fill the lake or pond. This process is called senescence. It is a natural stage in the change of a lake into dry land.
• Depending upon the climate, the size of the lake, and other factors, the natural ageing of a lake may span thousands of years.
• However, pollutants from man activities example- effluents from industries and residential premises, etc. can radically accelerate the ageing process. This phenomenon is termed as cultural or accelerated eutrophication.

Control of Eutrophication:

Following measures can be adopted to combat the phenomenon of Eutrophication-

• Wastewater must be treated before its discharge into water bodies.
• To reduce the amount of nutrients in the water body, bacterial growth should be stimulated.
• The dissolved nutrients can be removed by physio-chemical methods. For example- phosphorous can be removed by precipitation and nitrogen by nitrification or denitrification, electrodialysis, and ion exchange methods.

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