Environmental Pollution — Practice Questions
UPSC Prelims-pattern practice questions on pollution with explanations: photochemical smog, biomagnification, noise limits, eutrophication and plastic waste rules.
Questions
These are original UPSC-pattern practice questions. Attempt each one before revealing the answer.
Consider the following statements about photochemical smog:
- It is formed when sunlight acts on nitrogen oxides and hydrocarbons.
- Ozone and peroxyacetyl nitrate (PAN) are among its major components.
- It is a reducing smog typical of cold and humid conditions.
Which of the statements given above is/are correct?
Solution
Statements 1 and 2 are correct. Statement 3 is incorrect — photochemical smog is oxidising and typical of warm, sunny conditions. The reducing smog of cold, humid weather, rich in sulphur dioxide and soot, is classical (London) smog.
Answer: A
Biomagnification along a food chain is most likely to occur with pollutants that are:
Solution
Pollutants that are fat-soluble and persistent — DDT, methylmercury, some industrial chemicals — are stored in fatty tissue and not readily broken down or excreted, so their concentration rises at each higher trophic level. Rapidly degraded, water-soluble, volatile or biodegradable substances do not accumulate this way.
Answer: B
Under the Noise Pollution (Regulation and Control) Rules, 2000, in which of the following areas is the permissible daytime ambient noise limit the lowest?
Solution
Daytime limits in dB(A) Leq: industrial 75, commercial 65, residential 55, silence zone 50. Silence zones cover at least 100 metres around hospitals, educational institutions and courts.
Answer: D
Arrange the following stages of eutrophication in the correct sequence:
- Algal bloom
- Nutrient enrichment of the water body
- Depletion of dissolved oxygen as dead algae decompose
- Death of fish
Select the correct answer using the code given below.
Solution
Nitrogen and phosphorus enrich the water (2) → algae multiply rapidly (1) → when they die, decomposers use up dissolved oxygen (3) → fish die from lack of oxygen (4). Sequence: 2-1-3-4.
Answer: C
With reference to the Plastic Waste Management Rules, 2016 as amended, consider the following statements:
- Identified single-use plastic items were prohibited from 1 July 2022.
- The minimum thickness of plastic carry bags was raised to 120 microns with effect from 31 December 2022.
- Extended Producer Responsibility applies only to plastic manufacturers and not to brand owners.
Which of the statements given above is/are correct?
Solution
Statements 1 and 2 reflect the 2021 amendments to the rules. Statement 3 is incorrect — Extended Producer Responsibility applies to producers, importers and brand owners.
Answer: B
What is cultural eutrophication? Discuss its causes and consequences for Indian lakes and rivers, and suggest remedial measures.
Solution
Introduction: Eutrophication is the enrichment of a water body with nutrients, chiefly nitrogen and phosphorus. When human activity speeds up this naturally slow process, it is called cultural or accelerated eutrophication.
Body:
- Causes: untreated or partially treated sewage; runoff of fertilisers from farms; phosphate-based detergents; industrial effluents; reduced flow due to diversion and damming.
- Consequences:
- Algal blooms and weed infestation (for example water hyacinth) choking lakes.
- Low dissolved oxygen, fish kills and loss of biodiversity.
- Toxins from some blooms; unsafe drinking water and higher treatment costs.
- Loss of fisheries, tourism and recreational value; faster silting and shrinking of lakes.
- Remedies: expand sewage treatment and nutrient removal; balanced fertiliser use and buffer strips; regulate detergents; wetland-based natural treatment; de-weeding and dredging; community lake management.
Conclusion: Eutrophication is a symptom of nutrient mismanagement across a catchment; lasting solutions must treat the catchment, not only the lake.