Question

The process of 'eutrophication' is due to:
$A.$ increase in concentration of radioactive substances in water
$B.$ the reduction in concentration of the dissolved oxygen in water due to phosphate pollution in water
$C.$ increase in concentration of fluoride ion in water
$D.$ increase in concentration of insecticide in water

Answer 1

Hint: In this problem use the basic definition of Eutrophication, that is the process in which water bodies are abundantly filled with nutrients which results in abundant growth of simple plant life. This will help approaching the problem.

Complete step by step solution:

In Eutrophication there is excessive growth of algae and plankton in a water body. It is considered as a major environmental problem. Also, it contributes to water’s quality degradation and loss of dissolved oxygen in water bodies. Due to eutrophication the water gets converted into a bad quality of water and is known as eutrophic waters. They gradually transform into dead zones and they do not support life. In this there is enrichment of natural waters with inorganic nutrients which leads to an increase in algae and macrophyte in water bodies. As the lake dries, the eutrophication process occurs at a higher rate but in many cases the lakes are naturally eutrophic.
This occurs mainly where the artificial production of plant nutrients in many freshwater environments contributes to change in the environment and which leads to depletion of the water quality. As human population increases and also when there is more demand for water for agriculture also it occurs where there is deforestation, global warming, degradation of ozone layer and environmental disruption.
Eutrophication kills the equilibrium in habitats like plant and animal life in marine environments because due to this process simple plant life increases. It destroys many desirable organisms which decreases habitat biodiversity.
Eutrophication occurs mainly due to availability of nutrients such as nitrogen and phosphorus which restricts plant life growth within an ecosystem. In this water bodies are excessively filled with nitrogen and phosphorus which favours the growth of algae, plankton, and other simple plant life over the growth of more complex plant life.
Hence option B is the correct answer and as per this the process of 'eutrophication' is due to the reduction in concentration of the dissolved oxygen in water due to phosphate pollution in water.

Note: The oxygen overconsumption contributes to hypoxic conditions where oxygen supply is low in the water. The hypoxic conditions at lower water body levels contribute to the suffocation and eventual death of various forms of life such as fish etc.