UPSC CSE IAS · General Awareness
Environment & Pollution Control
Ecosystems, biodiversity, air/water/soil/noise pollution, waste, EIA, and the Indian Acts and boards that control pollution — the RRB JE CBT-2 environment block, also asked in…
Class-10 and diploma basics of environment and pollution control as RRB JE CBT-2 asks them in its ten-question block: what an ecosystem is, how air, water, soil and noise go wrong, why greenhouse warming is not the ozone hole, what waste and EIA are for, and which Indian Acts and boards actually control pollution. Almost nothing here computes — the product is pairing tables and night-before pegs.
- UPSC CSE IAS
- Medium level
- 6 concepts
- 42 practice questions
1Ecosystem, energy flow and biodiversity
An ecosystem is a working unit of nature: living organisms and the non-living surroundings they exchange energy and materials with. The living side is biotic — producers (green plants and algae that fix sunlight), consumers (animals that eat plants or other animals), and decomposers (bacteria and fungi that break dead matter back into nutrients). The non-living side is abiotic — light, temperature, water, air and soil. Biodiversity is the variety of life in that unit, examined at three levels: genes within a species, the species themselves, and the ecosystems they form.
Energy moves one way through a food chain (producer to herbivore to carnivore) and is not recycled the way carbon or nitrogen is. Lindeman's rule of thumb is that only about 10% of the energy at one trophic level is available to the next, which is why food chains stay short and why an energy pyramid is upright. A food web is several chains sharing species. Conservation in India is mostly in-situ (National Parks and Sanctuaries under the Wild Life (Protection) Act, 1972); a zoo or seed bank is ex-situ. Park rules are stricter than sanctuary rules: grazing and private rights are generally not allowed in a National Park.
How energy moves
- Producers fix sunlightGreen plants and algae convert solar energy into chemical energy. That is the only large incoming energy term the rest of the chain can spend.
- Each step keeps about 10%Lindeman's rule: roughly one-tenth of the energy at one trophic level is available to the next. The rest is used or lost as heat, so chains stay short.
- Matter returns; energy does notDecomposers recycle carbon, nitrogen and minerals. Energy is not recycled — that is the fork against biogeochemical cycles.
| Idea | What to lock |
|---|---|
| Biotic | Producers, consumers, decomposers |
| Abiotic | Light, temperature, water, air, soil |
| Food chain vs web | One path vs interconnected paths |
| Energy vs matter | Energy one-way (~10%/step); matter cycles |
| Biodiversity levels | Genetic, species, ecosystem |
| In-situ vs ex-situ | Park/sanctuary vs zoo/seed bank |
| Wild Life (Protection) Act | 1972; Park stricter than Sanctuary |
A field note lists sunlight, soil moisture and a fungal mat breaking down leaf litter beside a stand of grass. Which pairing of roles is correct?
- Sunlight and soil moisture are biotic; the fungus is an abiotic producer
- Sunlight and soil moisture are abiotic; grass is a producer; the fungus is a decomposer
- Grass and fungus are both abiotic; only sunlight is biotic
Light and moisture are abiotic. Grass fixes sunlight, so it is a producer. Fungi that break litter are decomposers. Living things are not abiotic, and sunlight is not an organism.
2Air pollution, greenhouse effect and ozone
Air pollution is unwanted gases and particles in the air we breathe. The staple industrial and vehicle set is sulphur dioxide (SO2), oxides of nitrogen (NOx), carbon monoxide (CO) from incomplete combustion, and suspended particulate matter (SPM / PM). SO2 and NOx dissolve to make sulphuric and nitric acids — that is acid rain, which weathers marble and acidifies soils and lakes. Photochemical smog needs sunlight acting on NOx and hydrocarbons; ground-level ozone in that mix is a lung irritant, not a shield.
The greenhouse effect and the ozone layer are different altitudes and different jobs. Greenhouse gases (carbon dioxide, methane, nitrous oxide, water vapour, CFCs) absorb outgoing long-wave heat in the troposphere; an enhanced greenhouse effect is global warming. The ozone layer sits in the stratosphere and absorbs most incoming UV-B. CFCs release chlorine that catalytically destroys stratospheric ozone — that is the Montreal Protocol (1987) problem, not the same treaty track as carbon-dioxide climate agreements.
Which layer, which job
- Name the altitudeTroposphere: weather and the greenhouse gases that trap outgoing heat. Stratosphere: the ozone layer that absorbs UV-B.
- Name the mechanismGreenhouse warming is absorbed infrared. Ozone protection is absorbed ultraviolet. Ground-level ozone in smog is a pollutant in the troposphere.
- Name the treaty trackMontreal Protocol (1987) phases out ozone-depleting substances such as CFCs. Carbon-dioxide climate agreements are a different track.
| Item | Lock this | Usual trap |
|---|---|---|
| Acid rain | SO2 and NOx → sulphuric and nitric acids | Calling CO2 the classic acid-rain pair |
| CO | Incomplete combustion; binds haemoglobin | Treating CO as the main climate gas |
| SPM / PM | Fine particles; lungs and visibility | Calling dust a greenhouse gas |
| Greenhouse gases | CO2, CH4, N2O, water vapour, CFCs; trap heat | Putting O2 or N2 in the list |
| Stratospheric ozone | Absorbs UV-B | Calling the ozone layer a greenhouse blanket |
| CFCs | Chlorine radicals destroy O3; Montreal 1987 | Treating Montreal as a CO2 climate treaty |
A poster says CFCs were banned because they are the main gas that traps heat and causes acid rain. What is wrong?
- Nothing — CFCs are the headline acid-rain and greenhouse pair
- CFCs are ozone-depleting substances (Montreal 1987); acid rain is SO2 and NOx, and the main fossil-fuel greenhouse gas is CO2
- CFCs cause acid rain only; ozone loss is caused by ordinary oxygen
Montreal targets ozone-depleting CFCs. Acid rain is the SO2/NOx story. Fossil-fuel CO2 is the headline greenhouse gas. CFCs can also be greenhouse gases, but that is not why the protocol exists, and they are not the acid-rain pair.
3Water and soil pollution
Water pollution is the addition of sewage, industrial effluent or agricultural runoff until a water body can no longer support its ordinary life. Biochemical oxygen demand (BOD) measures how much dissolved oxygen microbes use to oxidise the organic load: a high BOD means a dirty, oxygen-hungry stretch, not a clean one. Excess nitrogen and phosphorus (fertiliser, detergent, sewage) trigger eutrophication — an algal bloom, then a crash in dissolved oxygen when the bloom dies and decomposes, then fish kills.
Soil pollution is contamination or physical ruin of the land that grows food: persistent pesticides, heavy metals from industry, salinity and waterlogging from poorly drained irrigation, and erosion that strips topsoil. Persistent poisons that do not break down can biomagnify — tissue concentration rises at each trophic step, the opposite of energy, which falls.
How a lake eutrophies
- Nutrients arriveNitrate and phosphate from sewage, detergent or fertiliser enrich the water.
- Algae bloomProducers explode. The water may look green and 'alive' while the trouble is already loaded.
- Oxygen crashesWhen the bloom dies, decomposers consume dissolved oxygen. Fish and other aerobes die. That crash is the examinable end-state, not the green colour.
| Cue | Meaning |
|---|---|
| High BOD | High organic load; microbes demand oxygen |
| Low dissolved oxygen | Stressed aquatic life; often follows a bloom or a sewage slug |
| Eutrophication | Excess N and P → bloom → oxygen crash |
| Biomagnification | Persistent poison concentrates up the food chain |
| Soil salinity / waterlogging | Poor drainage and excess irrigation |
| Heavy metals / persistent pesticides | Industrial or agrochemical soil contamination |
A lake turns pea-green after monsoon fertiliser wash-off, then fish die a fortnight later. Which reading of BOD and cause is consistent?
- BOD falls because green water is oxygen-rich; the fish died of too much oxygen
- Nutrient-driven bloom, then decomposition raises oxygen demand; BOD is high and dissolved oxygen crashes
- The green colour is stratospheric ozone dissolving in the lake, which has no BOD
That is eutrophication: N and P feed a bloom; decay then consumes oxygen, so BOD is high and fish suffocate. Green water is not a sign of surplus oxygen, and ozone-layer chemistry is not a lake process.
4Noise pollution and waste
Noise is unwanted sound. It is measured in decibels (dB); Indian ambient limits are set by the Noise Pollution (Regulation and Control) Rules, 2000, and they differ by zone and by day versus night. A silence zone (hospitals, courts, educational institutions) is quieter than a residential area, which is quieter than commercial, which is quieter than industrial. Night limits are lower than day limits in every zone. Traffic, industry, construction and loudspeakers are the usual sources; hearing loss, sleep disturbance and raised stress are the usual effects.
Solid waste is the material we throw away. Biodegradable waste (kitchen peels, garden waste) is broken down by microbes; plastics, glass and many synthetics are non-biodegradable. The waste hierarchy taught at this level is Reduce, then Reuse, then Recycle — cutting generation beats clever disposal. Hazardous and biomedical wastes are not mixed into ordinary municipal heaps; they need separate handling. Landfills that bury wet waste generate methane, itself a greenhouse gas.
Waste hierarchy
- ReduceDo not generate the waste. This is the first and strongest move.
- ReuseUse the same object again before it becomes scrap.
- RecycleRecover material after the object is discarded. Necessary, but last of the three.
| Zone | Day dB(A) | Night dB(A) |
|---|---|---|
| Industrial | 75 | 70 |
| Commercial | 65 | 55 |
| Residential | 55 | 45 |
| Silence (hospitals, courts, schools) | 50 | 40 |
A hospital campus is notified as a silence zone. A night-time generator sits at 65 dB(A) beside the ward. Against the 2000 Rules limits, what is true?
- 65 dB(A) is legal at night because it matches the commercial night limit, and hospitals use the commercial row
- Silence-zone night limit is 40 dB(A); 65 dB(A) exceeds even the silence-zone day limit of 50 dB(A)
- Silence zones have no night limit; only industrial areas are regulated after 22:00
Silence zone: 50 dB(A) day, 40 dB(A) night. 65 dB(A) is the commercial day figure, not a hospital permission. Every zone, including silence, has a lower night cap.
5EIA and the Water, Air and Environment Acts
Environmental Impact Assessment (EIA) is a study of the likely effects of a proposed project on air, water, land, wildlife and people, done before the project is cleared. In India, EIA is framed under the Environment (Protection) Act, 1986; the 2006 EIA Notification is the main procedural home. The point is prediction and mitigation, not a report written after the factory is already running.
Three framework statutes set the rest of the legal pegs. The Water (Prevention and Control of Pollution) Act, 1974 created the Central and State Pollution Control Boards and the consent system for discharges to water. The Air (Prevention and Control of Pollution) Act, 1981 extended that machinery to air. The Environment (Protection) Act, 1986 is the umbrella statute, enacted after the 1984 Bhopal gas disaster, under which the Centre can make wide environmental rules — including EIA and later waste rules. Do not invert the Water and Air years: water is 1974, air is 1981, the umbrella is 1986.
What EIA is for
- Propose a projectA dam, highway, mine or factory is planned. Clearance is not automatic.
- Assess before approvalEIA describes likely effects and mitigations while the decision is still open. A post-construction brochure is not EIA.
- Decide under the 1986 ActThe Environment (Protection) Act is the umbrella that houses the EIA Notification (2006). Water 1974 and Air 1981 are the older media-specific Acts.
| Instrument | Year | Role peg |
|---|---|---|
| Water (Prevention and Control of Pollution) Act | 1974 | Water pollution; created CPCB and SPCBs |
| Air (Prevention and Control of Pollution) Act | 1981 | Air pollution; same boards gain air functions |
| Environment (Protection) Act | 1986 | Umbrella statute after Bhopal; EIA and rules |
| EIA Notification | 2006 | Main EIA procedure under the 1986 Act |
| Bhopal gas disaster | 1984 | The industrial disaster that precedes EPA 1986 |
A consultancy files an 'EIA' six months after a cement plant has already started kilns, and it dates the umbrella environment law to 1974. What is wrong?
- Nothing — EIA is a post-commissioning audit, and 1974 is the Environment (Protection) Act
- EIA is a before-clearance study; the umbrella Act is 1986 (after Bhopal 1984); 1974 is the Water Act
- EIA exists only under the Air Act 1974, so a cement plant needs no assessment
EIA is prospective. EPA 1986 is the umbrella, after Bhopal 1984. 1974 is Water, 1981 is Air. A post-start report is not EIA, and cement is not exempt because someone swapped the years.
6CPCB, SPCB and who enforces what
The Central Pollution Control Board (CPCB) is the national technical body created under the Water Act, 1974 and later given air functions under the Air Act, 1981. It advises the Central Government, coordinates the State boards, and lays down nationwide standards. A State Pollution Control Board (SPCB) — or a Pollution Control Committee in a Union Territory — is the body that monitors and enforces in that State: it grants or refuses consent to establish and consent to operate, and it samples local discharges.
The two boards are not interchangeable. A factory in a State does not write to CPCB for its ordinary consent; that file sits with the SPCB. CPCB is the coordinator and standard-setter, not the local consent clerk. The National Green Tribunal (2010) is a specialist forum for environmental disputes — it is not a third pollution-control board. Control strategies taught with this machinery are standards, consent, monitoring, and the polluter-pays idea: the person who pollutes bears the cost of prevention and remedy.
Who holds the file
- Standards sit at the CentreCPCB advises the Union and frames nationwide ambient and source standards, and it coordinates the State boards.
- Consent sits in the StateThe SPCB (or UT committee) grants or refuses consent to establish and consent to operate, and it inspects local discharges.
- Disputes are not a third boardNGT (2010) hears environmental cases. It does not issue ordinary industrial consents.
| Body | Home | What it does here |
|---|---|---|
| CPCB | Water Act 1974; Air Act 1981 | National standards; advise Centre; coordinate SPCBs |
| SPCB / PCC | State / Union Territory | Consent to establish and operate; local monitoring |
| NGT | 2010 | Specialist environmental tribunal, not a consent board |
| Polluter pays | Control principle | The polluter bears prevention and remedy costs |
A spinning mill in a State needs consent to operate a new dye-house discharge. Which filing is the ordinary path?
- Apply to CPCB in New Delhi, because only the Central Board can consent any discharge
- Apply to the SPCB (or UT committee) for consent; CPCB sets standards and coordinates, and NGT is not the consent office
- File only in the National Green Tribunal, which has replaced both boards since 2010
Ordinary consent is an SPCB (or PCC) file. CPCB is the national coordinator and standard-setter. NGT (2010) is a tribunal, not a replacement consent board.
Notes
- Ecosystem and energy flow: An ecosystem is the biotic side - producers, consumers and decomposers - working with the abiotic side of light, temperature, water, air and soil. Energy moves one way along a food chain and only about 10% of one trophic level reaches the next (Lindeman), which is why chains stay short; matter such as carbon and nitrogen cycles instead.
- Biodiversity and conservation: Biodiversity is examined at genetic, species and ecosystem levels. In-situ conservation keeps the organism where it lives - National Parks and Sanctuaries under the Wild Life (Protection) Act, 1972 - while a zoo or seed bank is ex-situ, and park rules are stricter than sanctuary rules.
- Air pollution, greenhouse effect and ozone: SO2 and NOx dissolve into sulphuric and nitric acids and give acid rain, and CO comes from incomplete combustion. Greenhouse gases trap outgoing heat in the troposphere, while the stratospheric ozone layer absorbs UV-B and is destroyed by chlorine from CFCs - the Montreal Protocol (1987) track, not a carbon-dioxide climate treaty.
- Water and soil pollution: A high biochemical oxygen demand (BOD) means a heavy organic load, not clean water. Excess nitrogen and phosphorus cause eutrophication - an algal bloom, then an oxygen crash when the bloom decomposes. Persistent poisons biomagnify up the food chain, the opposite of energy, which falls at every step.
- Noise and waste: Noise is measured in dB(A) and the Noise Pollution (Regulation and Control) Rules, 2000 set zone limits that are lower at night - silence zone 50/40, residential 55/45, commercial 65/55 and industrial 75/70. The waste hierarchy is Reduce, then Reuse, then Recycle; hazardous and biomedical waste is handled separately, and buried wet waste generates methane.
- Framework Acts and the boards: The Water Act, 1974 created the Central and State Pollution Control Boards, the Air Act, 1981 extended that machinery to air, and the Environment (Protection) Act, 1986 is the umbrella statute that houses EIA. CPCB sets national standards and coordinates the State boards; the SPCB grants consent to establish and to operate and does the local monitoring. The National Green Tribunal (2010) is a specialist forum, not a third board.
Formulas
- Trophic transfer: roughly 10% of the energy at one trophic level reaches the next (Lindeman), so a food chain rarely runs beyond four or five links; matter cycles but energy does not.
- Noise limits, dB(A), day/night: silence zone 50/40, residential 55/45, commercial 65/55, industrial 75/70 — night limits are always the lower pair.
- The three framework Acts: Water Act 1974 (created CPCB and the SPCBs), Air Act 1981 (extended them to air), Environment (Protection) Act 1986 (umbrella statute, houses EIA).
- Protected areas: National Park and Wildlife Sanctuary are in-situ under the Wild Life (Protection) Act, 1972, with park rules stricter; zoos, botanical gardens, seed and gene banks are ex-situ.
- Pollutant to effect: SO2 and NOx to acid rain, CO from incomplete combustion, CFC chlorine to stratospheric ozone loss (Montreal Protocol, 1987), high BOD to an organic load, excess N and P to eutrophication.
- Waste hierarchy: Reduce, then Reuse, then Recycle; hazardous, biomedical and e-waste each run under their own rules rather than the municipal stream.
Exam traps & shortcuts
- A high BOD reading means a heavy organic load, not clean water — the classic reversal in a water-pollution question.
- Energy falls at every trophic step while persistent poisons biomagnify upward. If an option makes both move the same way, it is wrong.
- Ozone depletion is the Montreal Protocol and stratospheric UV-B; the greenhouse effect is tropospheric heat. Papers routinely swap the two.
- CPCB sets national standards and coordinates; the SPCB grants consent to establish and to operate. The National Green Tribunal is a court, not a third board.
- A zoo, a botanical garden and a seed bank are ex-situ however "natural" they look; only the park and the sanctuary keep the organism where it lives.
Reference tables
If a stem names the idea, answer with the year; if it names the year, answer with the idea. Water before Air before the umbrella Act.
| Instrument | Year | One-line lock |
|---|---|---|
| Wild Life (Protection) Act | 1972 | In-situ categories; Park stricter than Sanctuary |
| Water Act | 1974 | Water pollution; CPCB and SPCBs created |
| Air Act | 1981 | Air pollution; boards gain air functions |
| Environment (Protection) Act | 1986 | Umbrella after Bhopal 1984; EIA and rules |
| Montreal Protocol | 1987 | Ozone-depleting substances (CFCs, halons) |
| Noise Rules | 2000 | Ambient dB(A) by zone and day/night |
| Biological Diversity Act | 2002 | Domestic biodiversity statute |
| EIA Notification | 2006 | Main EIA procedure under EPA 1986 |
| National Green Tribunal | 2010 | Specialist environmental forum |
Cross-cutting pairings this topic keeps returning to. Use them when a stem describes a river, a marble tomb, a food-chain poison, or a heat-versus-UV mix-up.
| Cue | Lock this |
|---|---|
| Acid rain | SO2 + NOx |
| Incomplete combustion | CO |
| Greenhouse (fossil headline) | CO2; also CH4, N2O, water vapour, CFCs |
| Stratospheric ozone | UV-B shield; CFCs destroy it |
| Ground-level ozone | Smog pollutant, not a shield |
| High BOD | Organic load; oxygen demand |
| Eutrophication | Excess N, P → bloom → oxygen crash |
| Biomagnification | Persistent poison concentrates upward |
| 3Rs | Reduce, then Reuse, then Recycle |
Recap
Read only this the night before.
- Ecosystem
- Biotic = producers, consumers, decomposers. Abiotic = light, temperature, water, air, soil. Energy one-way (~10%, Lindeman); matter cycles.
- Biodiversity
- Genetic, species, ecosystem. In-situ = Park/Sanctuary (Wild Life Act 1972); ex-situ = zoo/seed bank. Park stricter than Sanctuary.
- Acid rain
- SO2 and NOx → sulphuric and nitric acids. CO2 is not the classic pair.
- Greenhouse vs ozone
- GHGs trap heat in the troposphere (CO2 headline). Stratospheric O3 absorbs UV-B. Montreal 1987 = CFCs, not a CO2 climate treaty.
- Water / soil
- High BOD = dirty oxygen demand. Eutrophication = N, P → bloom → DO crash. Poisons biomagnify; energy does not.
- Noise
- Rules 2000. Industrial 75/70, commercial 65/55, residential 55/45, silence 50/40 dB(A) day/night.
- Waste
- Reduce > Reuse > Recycle. Kitchen peels biodegrade; plastics do not. Hazardous waste is not municipal mix.
- EIA
- Before clearance, not after start-up. Homes in EPA 1986; procedure in the 2006 Notification.
- Three Acts
- Water 1974, Air 1981, Environment (Protection) 1986 (after Bhopal 1984). Do not invert Water and Air.
- Boards
- CPCB = national standards and coordination. SPCB = State consent and monitoring. NGT 2010 = tribunal, not a third board.
Practise Environment & Pollution Control
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