Question

Which of the following statements about eutrophication are true?
I. It can be a naturally occurring process.
II. It is commonly found in standing rather than running water.
III. It can lead to oxygen depletion.
IV. It is commonly associated with high levels of nitrates and sulfates.
V. It is commonly associated with phosphates and Nitrates.

A. All of them.
B. I, II, III, and IV only.
C. II, III, and IV only.
D. I, II, III, and V only.

Answer 1

Hint: When the water body becomes rich in nutrients and results in the progress of plant life, it is known as eutrophication. This process occurs naturally and is commonly found in standing water. Also, it may lead to the depletion of oxygen. Nitrates and phosphates are the nutrients required for this process.

Complete step-by-step answer:

Eutrophication is the procedure by which a body of water becomes overly nutrient-rich, resulting in abundant progress of simple plant life. This process is indicated by the overgrowth of both algae and plankton in a body of water. The presence of nutrients like nitrogen and phosphorus in an ecosystem restricts the development of plant life.
Natural eutrophication is a kind of eutrophication that results in an overabundance of nutrients in water bodies as a result of natural events such as floods. It progresses more sluggishly than anthropogenic eutrophication. Thus, it is a natural process.
Eutrophication occurs whenever a water body becomes excessively nutrient-rich. It may result in dissolved oxygen depletion, decreased biodiversity, water intoxication, and the invasion of new species. Algal blooms are caused by eutrophication. Algae overcrowding causes a foul smell, depletes the dissolved amount of oxygen required by other aquatic organisms, and discharges toxins that poison a fish population. When algae die, they are accumulated just at the bottom and decompose, further diminishing the oxygen level. Eutrophication results in dead zones. So, we can say that it leads to oxygen depletion.

Hence, option D. is correct

Note: Freshwater eutrophication is caused mainly by phosphorus enrichment. Because, unlike phosphorus, nitrogen has an atmospheric source, it is generally present in levels equal to or greater than the amount needed for the aquatic growth of plants in lakes. So, nitrogen and phosphorus are nutrients needed for eutrophication. That’s why statement IV is correct.