What is oil pollution? What are its impacts on the marine ecosystem? In what way is oil pollution particularly harmful for a…

What is oil pollution? What are its impacts on the marine ecosystem? In what way is oil pollution particularly harmful for a country like India? (Answer in 150 words) 10 marks

हिंदी में प्रश्न पढ़ें

तेल प्रदूषण क्या है? समुद्री पारिस्थितिकी तंत्र पर इसके प्रभाव क्या हैं? भारत जैसे देश के लिए किस तरह से तेल प्रदूषण विशेष रूप से हानिकारक है? (उत्तर 150 शब्दों में दीजिए)

The question as printed in the 2023 General Studies paper

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Model answer

Drafted with AI by UPSC Answer Check against this question's marking rubric, to the 150-word length. UPSC does not publish answers for Mains — this is one way to score well, not an official key. How we build rubrics and answers.

Oil pollution is the contamination of marine environments by petroleum hydrocarbons, arising from accidental tanker spills, operational ship discharges, runoff, and natural seabed seeps.

Impacts on Marine Ecosystems: Floating oil slicks block sunlight and atmospheric gas exchange, inducing marine hypoxia and halting phytoplankton photosynthesis. Toxic chemical fractions bioaccumulate across trophic levels, causing long-term habitat degradation. Physiologically, oil coats seabird feathers and marine mammal fur, destroying thermal insulation and buoyancy. Ingestion of toxic compounds causes severe internal organ damage and reproductive failure across marine fauna.

Vulnerability for India: With an 11,098 km coastline, 12 major ports, and proximity to high-density Indian Ocean tanker sea lanes, India is acutely vulnerable, as the Ennore spills of 2017 and 2023 and the sinking of MSC Elsa 3 off Kochi in May 2025 showed. Oil spills severely threaten fragile mangrove ecosystems like the Sundarbans and Gulf of Kutch, disrupt ONGC offshore operations, and harm coastal tourism. Crucially, marine pollution imperils the food security and livelihoods of about 3.8 million marine fisherfolk.

Strengthening the National Oil Spill Disaster Contingency Plan (NOS-DCP) through the Indian Coast Guard and enforcing MARPOL conventions are essential to secure India's marine ecology.

How this answer will be evaluated

Framework: Environment: threat, causes, impact, mitigation

What earns full marks: Precise definition, specific marine impacts, and detailed India-specific analysis with examples.

Evaluation rubric

Each sub-part is marked on its own, against the marks and word limit printed on the paper.

The answer Define oil pollution, detail marine ecosystem impacts, and analyze specific harm to India. 10 marks · 150 words

explain— definition/context → points in order → small example → short close
Must cover
- Define oil pollution (hydrocarbon contamination)
- Marine impacts: oxygen depletion, food web disruption
- India-specific harm: coastal livelihoods, fisheries
- Mention specific Indian context (e.g., Mumbai, Chennai)
Loses marks
- Generic environmental writing without India focus
- Ignoring the 'marine ecosystem' specific impacts
- Aspirational solutions without implementation details
Earns more
- Mention specific species (e.g., Olive Ridley)
- Reference a specific spill (e.g., 2010 MSC Chitra off Mumbai, 2017 Ennore spill at Chennai)
- Mention economic loss in crores
- Reference the National Oil Spill Disaster Contingency Plan (Coast Guard)
Extra mark
- Mention specific cleanup technology (e.g., bioremediation)
- Reference to specific legal act (e.g., Environment Protection Act)

What "Explain" is asking you to do

Make the working of something clear — what sets it off, what follows from what, and what it produces. Explain is the Commission's mechanism word: it dominates the technical papers and the “explain why” stems, where the marks sit in the causal chain and not in the label.

Structure that answers it

State what it is → the initiating condition → the chain of cause, step by step → an instance where it plays out → what the chain produces

Where marks are lost

Describing what something looks like instead of why it works that way. Naming the stages without linking them reads as description too.

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