Question

Eutrophication causes reduction in
(a) Dissolved hydrogen
(b) Dissolved oxygen
(c) Dissolved salts
(d) All of the above

Answer 1

Hint: Eutrophication is a type of water pollution that occurs by anthropogenic activities like overgrowth of algae and plants. This occurs because of the high concentration of nitrogen and phosphorus in the water.

Complete step by step answer:
Eutrophication significantly reduces dissolved oxygen in water bodies. This mainly occurs when a water body becomes overly enriched with nutrients due to the excessive growth of algae or plankton. It is a serious concern because Eutrophication makes the water body incapable of supporting lives in it.

So, the correct answer is ‘Dissolved oxygen’.

Additional Information: Here's an explanation about Eutrophication:
- It makes the water bodies unsuitable for life.
- Excessive blooming of planktons and algae causes deterioration of water and depletion of dissolved oxygen in the water bodies.
- Some lakes are naturally eutrophic and mature lakes sometimes produce it too.
- In many cases nowadays, eutrophication is caused by human activities and is increasing with the increase in population and aggressive development of agriculture.
- Eutrophication caused by human activities is called cultured or accelerated eutrophication. The reasons can be throwing sewage and agricultural or industrial wastes into water bodies. This waste overstimulates algal growth, causes unpleasant odors, and pollutes, and toxicants the water source.
- Normally eutrophication causes an increase in inorganic materials in water bodies such as nitrogen and phosphorus. These nutrients increase the growth of algae and other simple plants which further reduces the oxygen quantity in the water.
- This reduces the growth of other organisms in the water and destroys the ecological balance as aquatic bodies are home to many organisms.
- These toxic blooms make the water toxic and can also be harmful to humans causing neurotoxic, paralytic, and diarrhetic shellfish poisoning.

Note: Although it is a natural process of aging of a water body, eutrophication gets accelerated when the water body becomes excessively nutrient and mineral- rich, mainly due to anthropogenic activities. This in turn increases phytoplankton in the water body and reduces the amount of Dissolved oxygen because these bacterial degradations of biomass consume oxygen. The main reason for the acceleration of eutrophication is the discharge of sewage and agricultural fertilizers in the water body that contains nitrogen and phosphorus.