Problem 16 - Chemistry in 30 days

Question

Eutrophication is process which irvolves (a) depletion of opone layer (b) increase in the concentration of owone in water (c) decrease in the conc. of dissolved oxygen in water by algae (d) decrease in the level of \(\mathrm{SO}_{2}\) in air

Step-by-Step Solution

Answer

The correct answer is (c): decrease in the concentration of dissolved oxygen in water by algae.

Step 1: Understanding Eutrophication

Eutrophication is a process occurring in water bodies where nutrients, especially nitrogen and phosphorus, lead to an excessive growth of algae. This growth affects aquatic environments and ecosystems.

Step 2: Analyzing Provided Options

We are given four options regarding eutrophication: (a) Depletion of ozone layer, (b) Increase in the concentration of ozone in water, (c) Decrease in the concentration of dissolved oxygen in water by algae, and (d) Decrease in the level of SO₂ in air.

Step 3: Assessing Option (a) - Ozone Layer

Option (a) refers to the depletion of the ozone layer, which is unrelated to eutrophication as the ozone layer concerns the atmosphere, not aquatic environments.

Step 4: Evaluating Option (b) - Ozone Concentration in Water

Option (b) mentions an increase in ozone concentration in water. Eutrophication is not related to ozone levels; it involves nutrient build-up leading to algae blooms.

Step 5: Considering Option (c) - Oxygen Concentration

Option (c) explains the decrease in dissolved oxygen due to algae growth. This is directly related to eutrophication since algae consume oxygen at night, reducing levels available for other organisms.

Step 6: Assessing Option (d) - SO₂ Level

Option (d) refers to SO₂ levels in air, unrelated to eutrophication, which is strictly about water quality and nutrient load.

Step 7: Selecting the Correct Option

Since eutrophication is tied to algae's impact on oxygen levels, the correct choice is (c) - the decrease in the concentration of dissolved oxygen in water by algae.

Key Concepts

Nutrient Pollution

Nutrient pollution occurs when water bodies receive an excess of nutrients, such as nitrogen and phosphorus. These nutrients often come from agricultural runoff, sewage, and industrial waste. They can lead to various negative environmental impacts.

• Sources: The most common sources of nutrient pollution include fertilizers used in farming and garden applications, and wastewater discharge from treatment plants.
• Impact: An oversupply of nutrients encourages the rapid growth of algae, which can create imbalances in aquatic ecosystems.
• Prevention: Reducing the use of fertilizers, improving wastewater treatment, and using nutrient management practices can help address nutrient pollution.

By following better agricultural and waste management practices, the harmful effects of nutrient pollution can be mitigated, protecting water bodies from degradation.

Algal Bloom

When nutrient pollution occurs, one of the most visible outcomes is the rapid increase in algae growth, known as algal bloom. This phenomenon can significantly alter aquatic ecosystems.

• Definition: Algal bloom is a rapid increase in the population of algae in a water system, often triggered by high nutrient levels.
• Effects on Water Body: Blooms can discolor water and produce harmful toxins that affect both wildlife and human health.
• Consequences: Toxic algal blooms can lead to fish kills, shellfish poisoning, and asthma attacks in sensitive individuals.

To prevent algal blooms, it is crucial to manage nutrient inputs and monitor water quality regularly.

Dissolved Oxygen Levels

Dissolved oxygen is crucial for the survival of aquatic life. However, eutrophication affects these oxygen levels, principally due to algal blooms. When algae die, they are decomposed by bacteria, which consume oxygen in the process, leading to lower dissolved oxygen levels. This process can create "dead zones," where the oxygen is too low to support most marine life.

• Effect on Aquatic Life: Fish and other organisms may suffocate if oxygen levels drop too low.
• Understanding Oxygen Depletion: Oxygen levels decrease as decomposition of algal biomass consumes more oxygen than what is produced.
• Indicators: Reduction in fish population and an increase in organisms that can tolerate lower oxygen conditions are indicators of low dissolved oxygen levels.

By managing nutrient inputs and monitoring algae growth, maintaining healthy dissolved oxygen levels in water bodies can be achieved.