Video on Eutrophication
Eutrophication
Overview
The resource describes the meaning, causes and effects of Eutrophication
Meaning of Eutrophication
Sometimes excess nutrients such as nitrogen and phosphorous compounds in formed in the water. This results in an explosive growth of algae. This is called as Eutrophication. This may lead to an algal bloom where foam or a green tide may appear in the waters. Besides algal blooms, eutrophication leads to depletion of oxygen in the water body. Eutrophication leads to decline in quality of water. The literal meaning of the term Eutrophication is ‘well fed’. In the mid 20th century this was looked upon as a type of water pollution. Ulsoor Lake in Bangalore has been affected by such Eutrophication leading to death of fish. Lake Udaisagar in Rajasthan received sewage water and industrial waste and was dominated by blue green algae. Agricultural runoff into the Baltic Sea has caused eutrophication. There are two types of eutrophication.. Natural eutrophication is seen due to aging of a water body. Artificial eutrophication is due to organic pollutants released by manmade activities.
Causes of Eutrophication
- Runoff from fields: Farmers use fertilizers and pesticides to increase their yield. Excess nitrogen and phosphorus from these can be washed away into nearby water bodies thus increasing the nutrients in the water body leading to eutrophication.
- Industrial waste let into waters: Industrial waste may contain compounds rich in nitrogen and phosphorus. Such waste may find its way to lakes and ponds causing eutrophication.
- Disposal of urban sewage: Detergents, soaps and dish washing liquids contain phosphorus. Waste water from households containing these compounds may find its way into water bodies leading to eutrophication.
- Atmospheric fallout from burning fossil fuels: Burning of coal, cowdung cakes, wood leads to formation of gases like carbon dioxide, nitrogen dioxide etc. These gases return back to the ground when dissolved in rain water and encourage the overgrowth of algae.
- Volcanic gases: In places where volcanic activity is high, the air contains gases that comes down with rain water. When such water enters the water body a rise in nitrogen and phosphorus compounds is seen leading to eutrophication.
Effects of Eutrophication
- Impact of fishing: Eutrophication leads to increase in algae and water plants. The plants block the surface of water and prevent dissolution of oxygen. Sometimes content of carbon dioxide in water increases. This slows the growth of fish and may prevent shell formation shellfish.
- Reduction in aquatic life: Because of the high concentration of organisms in a eutrophic system, there is often a lot of competition for resources. Animals and plants struggle to survive in such a system. As a result the diversity of organisms is lower in eutrophic than in oligotrophic (non eutrophic) systems.
- Algal blooms: Increasing biomass of phytoplankton results in 'algal blooms'. Such algal blooms change the colour of water and choke the surface of the water body. Sometimes bad smell is found and this increases pollution in the area.
- Reduced oxygen in water: Reduced dissolved oxygen content of a body of water is called as hypoxia. Such conditions are very common in eutrophic water bodies. Reduced oxygen is harmful to aquatic life.
- Spurt in diseases: Eutrophic water bodies have high concentration of phytoplankton. Some phytoplankton species produce toxins that cause severe symptoms such as diarrhea, memory loss, paralysis. Water from such sources is not fit for drinking.
- Rate of sedimentation increases: When the organisms causing eutrophication get decayed, they settle at the bottom of the water body. Such sedimentation can decrease the volume of the water body. It begins to shrink and thus the life span of the water body is lowered.