Answer:
Eutrophication effect
Step-by-step explanation:
The term eutrophication refers to the enrichment of surface water with nutrients. This process is related to human pollution activities.
Eutrophication is the biological process that generates in water by an oversupply of nutrients or organic matter. This matter, mainly compounded with nitrogen or phosphorous, favors the multiplication of phytoplankton (microscopic plants growing on the water surface) and other aquatic plants. This overgrowth leads to an enhance in primary productivity.
Little by little begin sedimentation, caused by the death of some vegetable organisms that sink in the bottom. These sediments rich in organic matter suffer decomposition in the presence of oxygen.
When oxygen disappears, anaerobic bacteria act and produce fermentation.
On the surface, plants and phytoplankton keep growing, creating a mantle that impedes the light to reach deeper areas. The overgrowth of phytoplankton on the water surface and the fermentation processes in the bottom originate toxic compounds that damage the animals. Animals die, creating more sediments in the bottom where there are anaerobic conditions. Decomposing processes and fermentation increases, producing a bad smell.
The result of eutrophication is the stratification of the water mass:
- First superficial layer, the overgrowth of blue-green algae produce toxins and interrupt the pass of light to deeper areas. The surface then becomes warmer.
- The second layer might have oxygen available for the animals.
- In the third layer, there is no oxygen, so life is not possible for animals or plants.
- In the fourth layer, there are animals and plants remains in the process of sedimentation.
- At the bottom, there is organic matter and anaerobic bacteria that are in charge of decomposition and fermentation, also producing toxic gases and smell.