Pollution: notes and MCQs for State PSC prelims

Pollution is part of Environment and Ecology. Below are notes on 13 sub-topics, followed by practice MCQs from State PSC and UPSC papers.

Air Pollution: Types, sources, primary & secondary pollutants, smog, acid rain, effects, control technologies & policies.

Air Pollution: Presence of undesirable material in the atmosphere in quantities sufficient to cause deleterious effects on living organisms and materials.
Non-Material Pollution: Thermal pollution (heat) is a non-material type of pollution.
Pollution Zones: Most air pollution is located in the Troposphere.
Man-made Pollutants: Also called Xenobiotics.
Natural Sources of Air Pollution: Forest fires, volcanic eruptions, decaying vegetation/ animal matter (H2S source), lightning (NO source).

Disadvantages: Higher installation & maintenance costs, complex grid connection, challenging marine environment, potential impact on marine ecosystems.

India's Wind Power Capacity: India has the 4th largest installed wind power capacity globally.
India's Potential: Estimated wind power potential of ~695 GW at 120m hub height (National Institute of Wind Energy - NIWE).
Key Indian States: Tamil Nadu, Gujarat, Maharashtra, Karnataka, Rajasthan, and Andhra Pradesh account for most of India's wind power capacity.
Offshore Wind in India: The first proposed offshore wind farm in India is near the Gujarat coast. NIWE is the nodal agency for wind energy development.
Benefits: Renewable, clean energy source (no greenhouse gas emissions during operation), reduces reliance on fossil fuels.
Challenges: Intermittency (wind variability), grid integration issues, high initial capital investment (especially offshore), specific environmental concerns.
Primary Pollutants: Emitted directly from a source.

Particulate Matter (PM): Solid residue/ tiny particles, an air pollutant.

Respirable Suspended Particulate Matter (RSPM) or PM10: particles < 10 µm in diameter.

diameter (can reach bloodstream).

PM1: extreme fine particles < 1 µm in diameter.
Sources: Motor vehicle exhaust, thermal power plants, industries.
Control: Electrostatic Precipitators (ESP) for fine particles, Cyclone collectors for coarser particles, Bag house filters.
Health Effects: Respiratory problems. Magnetite particles (from brakes/engines of vehicles, power plants, microwave stoves) may cause neurodegenerative problems.

Carbon Monoxide (CO):

Source: Incomplete burning of petrol, diesel, and other fossil fuels.
Effect: Combines irreversibly with hemoglobin (forming carboxyhemoglobin) 200-250 times faster than oxygen, reducing oxygen-carrying capacity, leading to suffocation and death. Affects Central Nervous System.
Control: Catalytic converters in vehicles.

Sulphur Dioxide (SO2):

Source: Burning of fossil fuels (especially coal), thermal power plants (largest source per EPA), copper smelting plants, industries (steel, X-ray films can be a source).
Effect: Impairs plant metabolism, causes leaf curling (in specific context, O3 also does), leads to acid rain. Lichens are excellent bioindicators of SO2 pollution.
Damage: Causes 'stone cancer' (e.g., Taj Mahal from Mathura refinery emissions).

Nitrogen Oxides (NOx): (NO, NO2)

Source: Motor vehicle exhaust, thermal power plants, industries (steel), lightning.
Effect: Respiratory ailments, contributes to acid rain and smog.

Hydrocarbons:

Source: Incomplete combustion of fossil fuels, industrial emissions. Methane (CH4) is the most abundant atmospheric hydrocarbon (main source in India: paddy fields).
Effect: Some are carcinogenic (e.g., Benzene: from automobile exhaust, tobacco smoke, wood burning, varnished furniture, polyurethane products).

Chlorofluorocarbons (CFCs):

Source: Refrigerators, air conditioners, aerosols, propellants.
Effect: Major cause of ozone layer depletion (Ozone hole).

Lead (Pb):

Source: Automobile exhaust (from leaded petrol, historically), industrial processes. Most hazardous metal pollutant from auto exhaust.
Effect: Damages liver, kidney, and central nervous system.

Fly Ash:

Source: Thermal power plants (coal-fired).
Composition: Contains silicon dioxide, calcium oxide, and toxic elements like arsenic, lead, mercury. Indian coal has high ash content.
Uses: Used in brick production, as a replacement for Portland cement in concrete.

Styrene Gas: (e.g., LG Polymers Plant, Vizag, 2020)

Used in polystyrene plastics/ resins, stored as liquid.
Effects: Short-term (mucous membrane/eye irritation, GI effects, inhalation problems), Long-term (CNS damage, fatality).

Methyl Isocyanate (MIC): (e.g., Bhopal Gas Tragedy, Dec 3, 1984) Highly toxic gas.

Secondary Pollutants: Formed by reactions of primary pollutants in the atmosphere.

Smog: Generic term for air pollution mixture.

Classical Smog (London Smog / Industrial Smog):
Occurred in London (1952).
Precursors: SO2, particulate matter, hydrocarbons.
Conditions: Damp, cool, high humidity.
Photochemical Smog (Los Angeles Smog):
Precursors: Nitrogen oxides (NOx) and Volatile Organic Compounds (VOCs)/hydrocarbons.
Conditions: Dry, sunny, high UV radiation. Formation often trapped by an 'inversion lid'.
Components: Ozone (O3), Peroxyacetyl Nitrates (PANs), Formaldehyde, Acrolein, Nitric oxide (NO). Does not contain CO2.
Effects: Irritates eyes (PAN is a powerful eye irritant), causes cracking of rubber, damages plant life. Excessive ozone triggers asthma.

Ozone (O3):

Formation: Secondary pollutant, produced by UV radiation reacting with NOx and VOCs/hydrocarbons.
Effect: Strong oxidant, causes leaf curling, respiratory issues.

Peroxyacetyl Nitrates (PANs):

Formation: Secondary pollutant, product of photochemical smog (NO2 + hydrocarbons).
Effect: Potent eye irritant, damages plants, can cause skin cancer.

Acid Rain: (pH < 5.6)

Causes: Atmospheric concentrations of Sulphur Dioxide (SO2) and Nitrogen Oxides (NOx) dissolving in rain.
Components: Primarily Sulphuric Acid (H2SO4) and Nitric Acid (HNO3). H2SO4 is often in higher concentration.
Effects: Corrodes buildings (especially limestone/marble), stone cancer, harms aquatic life, damages forests.
International Acid Rain Information Centre: Oslo.

Effects of Air Pollution:

Human Health: Respiratory diseases, cardiovascular problems, nervous system damage (Lead, CO), cancer (Benzene, PAN, UV light linked to skin cancer), suffocation (CO).
Environment: Acidification of soil/ water, damage to vegetation, corrosion of infrastructure/monuments, global warming (CO2, CH4, N2O, CFCs), ozone layer depletion (CFCs).
Plant Metabolism: SO2 impairs plant metabolism; O3 causes leaf curling; mango necrosis (black tip) due to SO2.

Air Pollution Control Technologies:

Catalytic Converters: Used in vehicles to reduce unburnt hydrocarbons (HC), carbon monoxide (CO), and nitric oxide (NOx). Require unleaded petrol.
Electrostatic Precipitators (ESP): Used to remove particulate matter (PM) from industrial exhaust gases (e.g., thermal power plants, cement kilns).
Scrubbers: Remove gaseous pollutants and particulate matter (e.g., Venturi scrubber).
Absorbers: Remove gaseous pollutants.
Adsorbents: Activated carbon, silica gel, iron oxide used for removing various gaseous pollutants.
Incineration: High-temperature combustion for gaseous pollutants/wastes.
Cyclone Collectors: Remove coarser particulate matter.
Cleaner Fuels:

Hydrogen: Produces least environmental pollution (water vapor).
Compressed Natural Gas (CNG): Cleaner than petrol/ diesel.
Hydrogen-CNG (HCNG): Reduces CO and NOx emissions compared to CNG.
AdBlue (Diesel Exhaust Fluid): Mixture of demineralized water and pure urea, used in BS 6 diesel engines to reduce NOx emissions (not SO2). Not toxic/ flammable.
Gasification: Converting coal to gaseous form to improve efficiency and cleanliness.

Ringelmann Scale: Used to measure density of smoke.

Policies & Standards in India:

The Air (Prevention and Control of Pollution) Act: Enacted in 1981. Amended in 1987 to include noise as an air pollutant.
National Ambient Air Quality Standards (NAAQS): Notified by CPCB in 1994 (revised 2009) for major pollutants including SO2, NO2, PM10, PM2.5.
Bharat Stage (BS) Emission Standards: Applicable to transport vehicles. Current standard is BS VI.
National Air Quality Index (AQI):

Launched in 2014 under Swachh Bharat Abhiyan.
Principle: "One Number- One Colour- One Description".
Monitors 8 pollutants: PM10, PM2.5, NO2, SO2, CO, O3, NH3, Lead (Pb). Does not include CO2 or Methane.
Categories (6): Good (0-50), Satisfactory (51-100), Moderate (101-200), Poor (201-300), Very Poor (301-400), Severe (401-500). Higher AQI value indicates greater pollution.

National Air Quality Monitoring Programme (NAMP): Regularly monitors SO2, NO2, PM10, PM2.5.
System of Air Quality and Weather Forecasting And Research (SAFAR): Advanced forecast system, developed by IITM Pune, measures UV-Index.
National Clean Air Programme (NCAP):

Launched in 2019 by MoEFCC.
Aim: Reduce particulate matter (PM) concentrations by 20-30% in 102 non-attainment cities by 2024.
Base year for comparison: 2017.
PRANA portal: Monitors NCAP implementation.

Government Industry Classification: 4color scheme based on pollution potential: Red (most polluting), Orange (moderately polluting), Green (significantly polluting), White (non-polluting).
Vehicular Pollution Factors in India: Older vehicles, high vehicle exhaust volume at traffic intersections, fuel adulteration. (Low vehicle density is not a cause of increasing pollution).
Largest Contributor to CO2 Emissions (India): Electricity and heat production.

Key Institutions & Committees:

Central Pollution Control Board (CPCB): HQ in New Delhi. Responsible for national ambient air quality standards and monitoring programs.
National Environmental Engineering Research Institute (NEERI): Located in Nagpur.
Bhure Lal Committee: Constituted by Union Government to monitor solutions to air pollution (especially in NCR).

Important Dates & Events:

Bengal Smoke Nuisance Act: 1905.
London Smog: 1952.
"Silent Spring" by Rachel Carson: 1962 (catalyzed environmental movement).
Air (Prevention and Control of Pollution) Act: 1981.
Bhopal Gas Tragedy: December 3, 1984 (Methyl Isocyanate leakage).
Air Act Amendment (Noise as pollutant): 1987.
Beijing Red Alert for Air Pollution: December 2015.
National Clean Air Programme (NCAP) launch: 2019.

Bioindicators:

Lichens: Excellent and reliable biological indicators of air pollution, especially for Sulphur Dioxide (SO2). They do not grow well in polluted areas.

Eutrophication: Process, causes, consequences, control measures.

Eutrophication is the natural or anthropogenic (cultural/accelerated) enrichment of a water body with nutrients.
It primarily occurs in lentic (still) water bodies like lakes and reservoirs, not typically lotic (flowing) waters.
Key Nutrients: Primarily nitrates (nitrogenous compounds) and phosphates (orthophosphates).
Major Causes/Sources of Nutrients:

Natural: Slow runoff from land over centuries.
Cultural/Accelerated: Human activities leading to excess nutrient input:

Agricultural runoff (excess inorganic fertilizers, animal waste).
Industrial discharge.
Domestic sewage/wastewater containing phosphates (e.g., from detergents) and ammonium.

Process and Consequences:

Excess nutrients lead to rapid, excessive growth of planktonic (free-floating) algae, forming an algal bloom.
Algal blooms cause deterioration of water quality (e.g., odor, reduced clarity).
When the algae die, decomposers (primarily aerobic bacteria) consume them, leading to a significant depletion of Dissolved Oxygen (DO) in the water.
This oxygen consumption results in a sharp increase in Biological Oxygen Demand (BOD).
Severe DO depletion leads to the death of aquatic life, particularly fish (fish mortality).
Areas with very low or no oxygen are called "dead zones," characterized by high BOD, excessive algal blooms, and excess nutrients.
Eutrophicated water is oxygen-depleted and generally unsafe for human consumption without treatment; it does not promote fish growth.

Control Measures:

Reduce nutrient loading into water bodies by treating sewage to remove nitrates and phosphates.
Minimize fertilizer runoff from agricultural lands.
Use phosphate-free detergents.

Eutrophication is a phenomenon associated with aquatic ecosystems.

Indoor Air Pollution: Sources, health effects, control measures.

Indoor Air Pollution (IAP): Air pollution present within or around buildings, affecting human health.
Sources & Key Pollutants:

Radon Gas: Naturally occurring radioactive gas from soil/rocks (uranium decay); enters through cracks. Most important indoor air pollutant (carcinogen).
Combustion Products (Biomass/Coal/ Kerosene/LPG burning): Major in India for cooking/heating, especially in rural areas.

Carbon Monoxide (CO): Odorless, colorless, toxic gas from incomplete combustion. Major indoor air pollutant in India.
Particulate Matter (PM): Fine particles, significant from burning biomass/coal.
Nitrogen Dioxide (NO2), Sulfur Dioxide (SO2), Polycyclic Aromatic Hydrocarbons (PAHs), Volatile Organic Compounds (VOCs), Formaldehyde.
Burning coal causes maximum indoor chemical pollution.
Burning mosquito coils also contributes significant chemical pollution.

Building Materials/Furnishings: Asbestos (insulation), Formaldehyde (plywood, particleboard, adhesives), VOCs (paints, solvents, carpets).
Consumer Products: Aerosol sprays (room sprays), cleaning agents, pesticides.
Biological Contaminants: Mold, mildew, bacteria, viruses, dust mites, pollen. Thrive in damp, humid conditions.

Mould growth: Principal threat to organic artefacts at high levels of Relative Humidity (RH).

Outdoor Air Infiltration: Outdoor pollutants like ozone, NO2, SO2 can enter indoors.

Health Effects:

Short-term: Eye/nose/throat irritation, headaches, dizziness, fatigue (e.g., CO poisoning).
Long-term: Respiratory diseases (asthma, bronchitis, COPD), lung cancer (Radon, Asbestos, PM), heart disease.

Control Measures:

Source Control: Eliminate or reduce pollutant sources (e.g., proper ventilation for combustion appliances, using low-VOC products, sealing cracks for radon).
Ventilation: Increase fresh air supply (open windows, exhaust fans, mechanical systems). Adequate ventilation helps prevent dampness.
Humidity Control: Maintain indoor RH between 30-50% to prevent mold and dust mites. Repair leaks promptly.

Avoid placing water pipes and drain pipes near sensitive areas (e.g., Record Room) to prevent dampness.

Air Cleaners/Purifiers: For removing particulates and some gases.

Light Pollution: Sources, ecological impacts, mitigation.

Light pollution refers to excessive or misdirected artificial outdoor light.
For highly light-sensitive objects (e.g., in museums, archives), a recommended maximum light level is often cited as 50 lux.
While maintaining light levels at or below 50 lux significantly reduces the rate of lightinduced damage to sensitive objects, it does not entirely eliminate damage, as degradation can still occur cumulatively over long periods, even at low intensities.

Marine Pollution: Sources (oil spills, plastics, sewage), impacts, prevention strategies.

Marine Pollution: Introduction of harmful substances or energy into the ocean, causing detrimental effects.
Sources of Marine Pollution:

Oil Spills: Accidental releases from tankers (e.g., Amoco Cadiz, Exxon Valdez), offshore platforms (e.g., Deepwater Horizon).
Methane Release: Nord Stream gas pipeline (2022) incident caused a large-scale accidental release of methane into the Baltic Sea.
Plastics: Microplastics (<5mm) & macroplastics (bags, bottles, fishing gear) from land-based runoff, litter, industrial discharge.
Sewage & Nutrient Pollution: Untreated domestic sewage, agricultural runoff (fertilizers) leading to eutrophication.
Red Tides: Excessive growth/blooms of pigmented dinoflagellates, often in estuaries, caused by nutrient pollution.
Chemical Pollutants: Pesticides, industrial chemicals, heavy metals, pharmaceuticals.
Coral Reef-Toxic Sunscreens: Chemicals like oxybenzone and octinoxate absorb UV light, harming corals. Palau was the first country to ban such sunscreens.
Other Sources: Noise pollution (shipping, sonar), thermal pollution, radioactive waste.

Impacts of Marine Pollution:

Loss of biodiversity, habitat destruction (coral reefs).
Bioaccumulation and biomagnification of toxins.
Physical harm to marine life (ingestion, entanglement of plastics).
Oxygen depletion ("dead zones") from eutrophication.

Prevention & Control Strategies:

Bioremediation: Use of microorganism metabolism to remove pollutants, such as oil spills.
Oilzapper: An eco-friendly technology developed by TERI (India) for the remediation of oily sludge and oil spills, utilizing bacterial consortium.
International Conventions: MARPOL (Prevention of Pollution from Ships), London Convention (Dumping of Wastes).
Waste Management: Reduce, Reuse, Recycle plastics; improved sewage treatment.
Clean Ocean Manifesto (UNEP): Aims to reduce marine debris by 20-50% and implement a globe-circling & high-tech system of monitors.
Policy & Regulations: Bans on harmful substances (e.g., Palau's sunscreen ban).

Noise Pollution: Sources, impacts on health & wildlife, permissible limits, mitigation.

Noise Pollution: Unwanted or excessive sound that can disrupt human or animal life.
Noise Level Thresholds:

Noise above 65 dB is generally considered pollution.
Noise above 70 dB is harmful (WHO).
Noise above 70-75 dB is considered noise pollution (general threshold).
Noise above 80 dB is considered hazardous.
Sound above 85 dB for >8 hours is dangerous.
WHO recommended safe noise level for a city: 45 dB.

Sources of Noise Pollution:

Industrial: Machinery, factories, generators.
Transportation: Road traffic (vehicles, honking), railway, aircraft.
Domestic/Community: Household appliances, loudspeakers, construction activities, social events, firecrackers.
Natural: Thunderstorms, volcanoes (less frequent source of human-related concern).

Impacts on Human Health:

Hearing Impairment: Temporary Threshold Shift (TTS – temporary hearing loss), Permanent Threshold Shift (PTS), Tinnitus.
Physiological Effects: Increased blood pressure, cardiovascular disease risk, sleep disturbance, headaches, fatigue.
Psychological Effects: Stress, anxiety, irritability, reduced concentration, impaired cognitive performance.
Interference with communication.

Impacts on Wildlife:

Disruption of communication (mating calls, warnings).
Interference with navigation and foraging.
Increased stress levels, altered behavior.
Habitat abandonment and reduced reproductive success.
Difficulty detecting predators or prey.

Permissible Noise Limits (India - Noise Pollution (Regulation and Control) Rules, 2000):

Daytime (6 AM - 10 PM) / Nighttime (10 PM - 6 AM):
Industrial Area: 75 dB / 70 dB
Commercial Area: 65 dB / 55 dB
Residential Area: 55 dB / 45 dB
Silent Zone (100m around hospitals, educational institutions, courts): 50 dB / 40 dB

Mitigation Strategies:

Source Control: Designing quieter equipment, proper maintenance of vehicles/machinery, restricting honking, limiting use of loudspeakers.
Propagation Path Control:

Green Muffler: Planting dense trees/shrubs along roadsides, industrial areas, and residential zones to absorb and deflect sound, reducing noise pollution.
Construction of sound barriers/ acoustic walls.
Lining walls and ceilings with sound-absorbing materials (e.g., mineral wool, acoustic foam) to reduce air-borne noise and reflection.

Receiver Control: Use of earplugs/ earmuffs in noisy environments.
Planning & Regulatory Measures: Zoning regulations, traffic management, enforcing Noise Pollution (Regulation and Control) Rules, 2000.

Persistent Organic Pollutants (POPs) and Heavy Metal Pollution: Characteristics, sources, biomagnification, effects, relevant conventions.

conventions.

Persistent Organic Pollutants (POPs):

Characteristics: Highly toxic, resistant to degradation (non-biodegradable), bioaccumulate in tissues, biomagnify through food webs, can travel long distances, semi-volatile.
Examples:

DDT (Dichlorodiphenyl Trichloro Ethane): First chlorinated organic insecticide. Paul Muller awarded Nobel Prize in 1948 for its effectiveness. Effective against mosquitoes (malaria) and lice (typhus). High toxicity towards fish. Not easily metabolized by animals. A non-biodegradable pollutant.
Pesticides (General): Carbofuran, Methyl parathion, Phorate, Triazophos (used in agriculture).
Methyl Isocyanate (MIC): Toxic gas, involved in Bhopal disaster (Dec 1984), used in Union Carbide factory for pesticide production.
Brominated Flame Retardants: Used in mattresses, upholstery. Concern due to resistance to degradation and ability to accumulate in humans and animals.

Biomagnification: The increase in concentration of a non-biodegradable toxicant at successive trophic levels in a food chain.

Large fishes of a pond have higher concentration of pesticides than planktons.
Organisms at higher trophic levels (e.g., tuna, tertiary consumers like snakes, cattle consuming contaminated feed) show the highest concentration.

Bioaccumulation: Process of progressive accumulation of heavy metals and pesticides in an individual organism over time.
Pesticide Treadmill: Refers to the increase in doses of pesticides required to prevent the resurgence of pests that were being controlled, due to pest resistance development.
Relevant Conventions:

Stockholm Convention (on POPs): A global treaty to protect human health and the environment from POPs. Aims to eliminate or restrict the production and use of POPs.
"Dirty Dozen": Refers to the initial 12 POPs targeted by the Stockholm Convention.
India ratified the Stockholm Convention in 2006.

Key Literature: "Silent Spring" (1962) authored by Rachel Carson, highlighting the dangers of DDT and pesticides.

Heavy Metal Pollution:

Characteristics: Toxic, non-biodegradable, accumulate in organisms, biomagnify.
Specific Metals and Effects:

Mercury (Hg):
Sources: Pesticides, dental amalgam fillings, fluorescent lamps, coal-based thermal power plants, gold mining activity. Automobile exhaust.
Effects: Minamata disease (neurological syndrome, numbness, muscle weakness, damage to hearing, speech, vision, can be fatal). Caused by consuming fish/shellfish contaminated with organic mercury (methylmercury). There is no known safe level of exposure to mercury.
Minamata Convention (2013): A global treaty to reduce mercury pollution, aimed at protecting human health and the environment from anthropogenic emissions and releases of mercury and mercury compounds.
Cadmium (Cd):
Sources: Industrial discharge, mining, batteries, paints. Absorbed by plants along with Zinc (Zn).
Effects: Itai-itai disease (also known as "Ouch Ouch" disease). Characterized by severe pain in bones and joints, osteomalacia (softening of bones), and kidney damage.
Lead (Pb):
Sources: Automobile exhaust (most toxic metal pollutant), old paints, batteries, industrial processes.
Effects: Neurological damage (especially in children), anemia, kidney damage, reproductive issues.
Arsenic (As):
Sources: Geogenic (groundwater contamination), industrial activities, some pesticides.
Effects: Black Foot Disease (a peripheral vascular disease leading to gangrene), skin lesions, various cancers, neurological issues.
Fluoride (F):
Sources: Natural groundwater (excess levels), industrial emissions.
Effects: Fluorosis (dental and skeletal), KnockKnee Syndrome (skeletal deformities). Indigestion is not a typical effect.
Nitrate Ion: Can cause Blue Baby Syndrome (Methemoglobinemia) in infants.

Other Relevant Pollutants/Concepts:

Asbestos: Causes Mesothelioma (a malignant tumor).
Metanil Yellow: A non-permitted food colorant, harmful if present in food items.
Nanoparticles: Concern exists as they can accumulate in the environment, contaminate water and soil, enter food chains, and trigger the production of free radicals.
Hazardous Waste Conventions:

Basel Convention: Regulates the Transboundary Movement of Hazardous Wastes and their Disposal. Addresses POPs and heavy metals as hazardous wastes.
Rotterdam Convention (Prior Informed Consent Procedure): Focuses on hazardous chemicals and pesticides in international trade, requiring informed consent from importing countries.

Plastic Pollution & Microplastics: Sources, ecological & health impacts, management strategies.

Plastic Nature: Plastics are non-biodegradable materials.
Non-biodegradable Examples: Plastic, bakelite, DDT, thermocol, glass bottle, aluminium foil, many lab detergents.
Biodegradable Examples: Wood, paper, leather, wool, plates made from dried leaves, domestic sewage, soap, plant leaves.
Microplastics: Small plastic particles (generally <5mm) resulting from the breakdown of larger plastics or directly manufactured.
Microbeads: A type of microplastic, they are a great concern primarily due to their harmful impact on marine ecosystems (e.g., ingestion by marine life, transfer of toxins).
Health Impacts (Chemicals):

Bisphenol A (BPA): An endocrine disruptor harmful to human health.
BPA Sources: Released from plastic items such as plastic coffee mugs and plastic water storage bottles.
Other harmful chemicals: Phthalates (often found in plastic toys).

Management Strategies (India):

Plastic Wastes (Management & Handling) Rules, 2011: Banned the manufacturing of plastic bags less than 40 microns thickness.
Plastic Waste Management Rules, 2016: Replaced 2011 rules, increasing the minimum thickness of plastic carry bags to 50 microns.

Product Bans: Government bans on certain products (e.g., imported toys) are often based on health and safety concerns (e.g., presence of lead or phthalates) rather than solely the non-biodegradable nature of the plastic material.

Radioactive Pollution: Sources, health & environmental impacts, waste management.

Radioactive Pollution: Release of radioactive substances into the environment, causing harm to living organisms.
Sources:

Natural: Cosmic rays, terrestrial radiation (e.g., Radon gas from uranium decay in soil/rocks).
Anthropogenic: Nuclear power generation (accidents like Chernobyl, Fukushima), nuclear weapons testing/ production, medical applications (Xrays, radiotherapy), industrial uses (tracers, gauges), mining of radioactive ores.

Health Impacts:

DNA Damage & Mutations: Leading to genetic defects and hereditary diseases.
Cancers: Leukemia, thyroid cancer (e.g., Iodine-131), bone cancer (e.g., Strontium-90), lung cancer.
Acute Radiation Sickness: Nausea, vomiting, hair loss, hemorrhage, immune suppression, and death at high doses.
Strontium-90: Highly dangerous betaemitter; mimics calcium, accumulates in bones/teeth, causes bone cancer and leukemia. (Relevant to MCQ 1)
Birth defects and developmental abnormalities.

Environmental Impacts:

Contamination of soil, water, and air, affecting ecosystems for extended periods.
Bioaccumulation and biomagnification of radioisotopes in food chains.
Genetic damage, reduced fertility, and mortality in flora and fauna.
Long-term habitat degradation and rendering areas uninhabitable.

Waste Management:

Categorization: Low-Level Waste (LLW), Intermediate-Level Waste (ILW), High-Level Waste (HLW).
Methods:

Disposal: Deep geological repositories (for HLW), near-surface disposal (for LLW).
Storage: Temporary storage in cooling pools or dry casks.
Treatment: Vitrification (encasing HLW in glass), reprocessing (separating reusable materials).

International Atomic Energy Agency (IAEA): Promotes safe, secure, and peaceful uses of nuclear science and technology, including setting safety standards for radioactive elements and their waste management globally. (Relevant to MCQ 2)

Soil Pollution: Causes, effects (contamination, degradation), remediation techniques.

Soil Pollution Causes:

Agricultural Chemicals:

Pesticides: Many are non-biodegradable pollutants. E.g., Herbicides like Sodium chlorate, Pronamide (used for controlling parasitic Cuscuta weed in lucerne crop).
Excessive use of chemical fertilizers.

Irrigation: Over time, can contribute to the salinization of agricultural lands.
Industrial Waste: Discharge of toxic heavy metals and chemicals.
Mining: Heavy sand mining in riverbeds can cause pollution of groundwater and lowering of the water-table.
Urban & Domestic Waste: Non-biodegradable waste (e.g., plastics, e-waste).
Natural Sources: Fluoride in the environment primarily comes from minerals like fluorite (and apatite).

Soil Pollution Effects (Contamination & Degradation):

Contamination: Presence of pollutants (pesticides, heavy metals, industrial chemicals).
Degradation:

Salinization: Accumulation of salts, often due to irrigation.
Alkalinity: Increase in soil pH.
Loss of Fertility: Imbalance of nutrients.
Groundwater Pollution: Pollutants leach into underground water sources.
Lowering of Water-table: E.g., due to sand mining.
Impact on Soil Properties: High organic matter in soil increases its water holding capacity (not reduces).
Disruption of Biogeochemical Cycles: Soil plays a crucial role in nutrient cycles like the sulphur cycle.

Soil Pollution Remediation Techniques:

Bioremediation:

Definition: Process of using microbes (microorganism metabolism) to treat areas of land or sea contaminated by pollutants (e.g., pesticides, oil, solvents) by enhancing natural biodegradation processes.
Advantages: It enhances natural biodegradation; genetic engineering can create microorganisms specifically designed for bioremediation.
Limitations: Any contaminant with heavy metals such as cadmium and lead cannot be readily and completely treated by bioremediation using microorganisms alone.

Chemical Remediation:

Gypsum: Long-term solution for soil salinity and alkalinity (especially for sodic soils).

Sustainable Agricultural Practices: Crop rotation, organic farming, reducing chemical inputs.
Phytoremediation: Using plants to remove or stabilize pollutants.
Waste Management: Proper collection, segregation, and disposal of industrial, urban, and domestic waste.

Solid Waste Management: Types of waste (municipal, industrial, hazardous, e-waste), collection, treatment, disposal, policies.

Types of Waste:
Municipal Solid Waste (MSW): Waste from households, commercial establishments, and institutions.
Biodegradable Waste: Decomposed by microorganisms (e.g., bacteria). Examples: Wood, leather, fruit peels, farm waste, livestock excreta, vegetable waste.
Industrial Waste: Generated from manufacturing processes. E.g., Granulated slag from Iron & Steel industry.
Hazardous Waste: Possesses properties dangerous to human health or the environment.
E-Waste (Electronic Waste): Discarded electrical or electronic devices.
Main e-waste contributors: Small household appliances (toasters, coffee makers, irons, hair dryers), personal computers, telephones, mobile phones, laptops, printers, scanners, photocopiers.
E-waste can release toxic substances like Beryllium, Cadmium, Chromium, Mercury, and Lead.
Red Category Waste: Includes drug waste.
Waste Collection & Segregation:
Solid Waste Management Rules, 2016, mandate waste generators to segregate waste into minimum three streams: wet, dry, and domestic hazardous waste.
Waste Treatment & Disposal Methods:
Landfilling: Deposit refuse, compact with bulldozers. Low-cost, but has long-term environmental impact.
Sanitary Landfills: Engineered landfills, isolated from environment. Primarily release Methane gas from anaerobic decomposition.
Incineration: Burning of waste in a furnace (incinerator). Reduces waste volume, but emits pollutants.
Composting: Decomposition of biodegradable waste by microorganisms in pits to produce humus-like material. Rich in organic matter and nutrients. Ideal temperature: 50°C-60°C.
Vermicomposting: Composting accelerated by earthworms.
Pyrolysis: Thermal decomposition of organic materials in the absence of oxygen.
Pulverizing: Mechanical reduction of waste size (grinding/crushing).
Recycling: Processing used materials into new products. Conserves resources, requires infrastructure.
Paper recycling originated in the UK.
Electric arc furnace is used for recycling Iron (Fe).
Green Dot Programme (Germany): Initiated for recycling of packaging waste.
Biological Treatment: Activated sludge process is a biological treatment method for waste.
Optimum temperature for sludge digestion: 37°C.
Policies & Regulations (India):
Solid Waste Management Rules, 2016 (SWM Rules, 2016):
Notified under The Environment (Protection) Act, 1986.
Applicable to all urban local bodies, census towns, industrial townships, Indian Railways, airports, Special Economic Zones, etc.
Provides criteria for identification of sites for landfills and waste processing facilities.
e-Waste (Management and Handling) Rules, 2011: Introduced "Extended Producer Responsibility" (EPR).
Maharashtra has the maximum number of registered E-Waste recyclers/dismantlers in India.
International Conventions:
Basel Convention (on the Control of Transboundary Movements of Hazardous Wastes and Their Disposal):
International treaty to protect human health and the environment against adverse effects of hazardous wastes.
Aims to reduce the movement of hazardous waste between nations, particularly from developed to less developed countries.
Signed in March 1989 in Basel, Switzerland.
Key Cities/Concepts:
Mumbai generates the largest solid waste per capita annually in India.
Indore is recognized for adopting the 'zero waste concept' in solid waste management.

Thermal Pollution: Sources, impacts on aquatic ecosystems, control.

Thermal Pollution Definition: Discharge of waste heat (mainly from industrial processes, power generation) into natural water bodies or the atmosphere, causing detrimental changes to ambient temperature (MCQ 2).
Sources:

Thermal Power Plants & Nuclear Power Plants: Major sources, releasing heated coolant water.
Industrial Effluents: From steel, paper, textile, chemical, etc., industries.
Hydro-electric Power: Damming can alter natural flow and temperature regimes.
Deforestation: Removal of riparian vegetation increases direct solar radiation on water bodies.

Impacts on Aquatic Ecosystems:

Decreased Dissolved Oxygen (DO): As water temperature increases, the solubility of oxygen decreases significantly (MCQ 1).
Increased Metabolic Rate: Warmer water increases the metabolic rates of aquatic organisms, leading to a higher demand for oxygen.
Oxygen Starvation: The combined effect of decreased DO and increased O₂ demand leads to oxygen stress or starvation for aquatic life (MCQ 1).
Altered Enzyme Activity & Metabolism: High temperatures denature enzymes and disrupt physiological functions.
Reproductive & Growth Impacts: Affects breeding, growth rates, and overall development of aquatic organisms.
Disruption of Food Chains: Alters species composition and distribution, leading to shifts in ecosystem balance.
Migration Patterns: Disrupts fish migration, especially for species sensitive to temperature changes.
Increased Susceptibility to Diseases: Weakened immunity in stressed organisms.
Thermal Shock: Sudden temperature changes can be lethal to aquatic life.
Algal Blooms: Favors the growth of certain tolerant species, like blue-green algae, which can lead to eutrophication.

Control Measures:

Cooling Ponds/Lakes: Allow hot water to cool naturally before discharge.
Cooling Towers:

Wet Cooling Towers: Evaporation of water dissipates heat.
Dry Cooling Towers: Transfer heat to the atmosphere without water loss.

Cogeneration (Combined Heat and Power - CHP): Utilizing waste heat for other productive purposes (e.g., district heating, industrial processes).
Discharge into Larger Water Bodies: For greater dilution and heat dissipation, reducing localized impact.
Afforestation/Reforestation: Planting trees along water bodies to provide shade and reduce solar heating.

Water Pollution: Sources, common pollutants, water quality indicators (BOD, COD, DO), effects, control measures.

Sources of Water Pollution:

Domestic Sewage: Major source of organic matter, nutrients (Nitrogen, Phosphorus), and pathogens (E. coli, protozoa, parasitic worms). Leads to increased BOD and decreased DO.
Industrial Effluents: Heavy metals (Mercury, Lead, Cadmium, Arsenic, Zinc, Copper, Nickel), acids, alkalis, toxic chemicals (Phenol), suspended solids, thermal pollution. Industries include Leather, Paper, Textile, Rayon.
Agricultural Runoff:

Excess Fertilizers: Nitrogen (Nitrates leaching into groundwater cause Methemoglobinemia/Blue Baby Syndrome, increase soil acidity), Phosphates (cause eutrophication). Neem-coated urea slows nitrogen release, reducing leaching.
Pesticides: Insecticides and Herbicides.

Radioactive Wastes: Water-soluble radioactive isotopes.
Oil Spills: Leads to oxygen depletion and distress to aquatic animals.
Solid Waste: Landfills and direct dumping.
Naturally Occurring Pollutants: Arsenic (e.g., Bangladesh, parts of West Bengal like Kolkata; causes Black foot disease), Fluoride (e.g., Nalgonda method for removal), Uranium.

Common Pollutants and their Effects:

Organic Matter: Increases BOD, decreases DO, promotes microbial growth.
Pathogens: Cause water-borne diseases like Cholera, Typhoid, Jaundice (Hepatitis-A). Hepatitis-B is not waterborne. E. coli is an indicator for faecal contamination.
Nitrates: Cause Methemoglobinemia (Blue Baby Syndrome) in infants.
Phosphates: Primary cause of eutrophication and algal blooms.
Heavy Metals:

Arsenic: Causes Black foot disease. WHO standard for drinking water: 0.01 mg/L.
Mercury: Causes Minamata disease.
Cadmium: Causes Itai-itai disease.
BIS 10500:2012 Drinking Water Standards (Acceptable limits): Iron (Fe): 0.3 mg/L, Manganese (Mn): 0.1 mg/L, Copper (Cu):

Other Chemicals: Phenol. Potassium Bromate (a probable carcinogen; banned as food additive in India by Union Government based on FSSAI recommendation after CSE study).
Sulphur Dioxide (SO₂): Primarily an air pollutant, not a water pollutant.

Water Quality Indicators:

Dissolved Oxygen (DO):

Amount of oxygen dissolved in water, essential for aquatic life.
Higher DO indicates cleaner water. Lower DO indicates pollution.
Inversely proportional to water temperature (low temp = high DO).

Biochemical Oxygen Demand (BOD):

Amount of oxygen consumed by microorganisms to decompose organic matter (typically over 5 days at 20°C, in mg O₂/L or ppm).
A measure of organic pollution and microbial activity. High BOD indicates high microbial pollution and oxygen depletion.
Unpolluted river water: BOD < 5 mg O₂/L (or ppm).
Clean drinking water: BOD should be very low (ideally near 0 ppm).
Increased organic matter (e.g., sewage) enhances BOD due to increased bacterial population.

Chemical Oxygen Demand (COD): Oxygen required for chemical oxidation of all organic and inorganic pollutants; generally higher than BOD.
pH: Measures acidity/alkalinity. Acceptable range for drinking water
Turbidity: Cloudiness due to suspended solids. Measured in NTU (Nephelometric Turbidity Unit).
Coliform Count (e.g., E. coli): Indicator of faecal contamination; absence denotes purity. E. coli normally grows in the large intestine of human beings.

Effects of Water Pollution:

Health Impacts: Major cause of poor health in India. Water-borne diseases, heavy metal poisoning (Black foot disease from Arsenic, Methemoglobinemia from Nitrates).
Ecological Impacts:

Oxygen depletion leads to fish kills and loss of aquatic biodiversity.
Eutrophication: Nutrient enrichment causes algal blooms, blocking sunlight, and further depleting DO upon decomposition.
Biomagnification of toxins in food chains.
Larvae of stoneflies (Plecoptera) are indicators of clean water and are absent in polluted water. Water hyacinth, blue-green algae, and hydrilla can proliferate in polluted waters.

Control Measures and Treatment Technologies:

Wastewater Treatment (Sewage Treatment Plants - STPs): Preliminary Treatment (Screen1. ing): Removes large debris. Primary Treatment: Sedimenta2. tion (removes many suspended solids, greases). Secondary (Biological) Treat3. ment: Biodegradation of organic matter by microbes (e.g., Activated Sludge Process). Significantly reduces BOD. Involves algal-bacterial symbiosis and photosynthetic oxygenation in some systems (e.g., stabilization ponds). Tertiary Treatment: Advanced 4. removal of specific pollutants (nutrients, heavy metals). Denitrification converts nitrates to nitrogen gas. Phosphate removal uses coagulants like Aluminium Sulphate. Disinfection: Chlorination (most 5. common, can be pre- or posttreatment), UV radiation, Ozonation. Pre-chlorination is adding chlorine to raw water before treatment.
Advanced Water Treatment Technologies:

Membrane Bioreactors (MBRs): Combine activated sludge with membrane filtration for wastewater treatment.
Nanofiltration: Water filtered through membranes with porosity of 1-100 Angstroms.
Ultrafiltration: Removes suspended solids, bacteria, protozoa.
Electro-dialysis: Removes ions (e.g., heavy metals like mercury) from water.
Ion exchange, Reverse osmosis: Other advanced water purification methods.
Nalgonda method: Developed in India for fluoride removal.
Electrostatic precipitation is an air pollution control technique, not water treatment.

Industrial Waste Treatment:

Common Effluent Treatment Plants (CETPs): First in India commenced in Andhra Pradesh (1989) for small-scale industries.
Specific treatments for pollutants like phenol (biological oxidation).

Agricultural Practices: Judicious use of fertilizers and pesticides. Promoting neem-coated urea.
Phytoremediation: Using plants like Water Hyacinth (Eichhornia crassipes), also known as "Terror of Bengal," to absorb pollutants.
Bio-toilets (Indian Railways): Use anaerobic bacteria to decompose human waste into biogas (methane, CO2) and water, not fungal inoculum or just ammonia/water vapour.

Relevant Acts, Programs, and Institutions:

Water (Prevention and Control of Pollution) Act: Enforced in 1974.
Central Pollution Control Board (CPCB): Established under the Water Act, 1974. Responsible for controlling river pollution, monitoring air pollution, issuing sewage disposal and effluent treatment guidelines, and publishing data.
Ganga Action Plan (GAP): Launched in 1985; aimed to make Ganga pollution-free.
Central Ganga Authority: Constituted in 1985.

10. Water Conservation

Practice MCQs: Pollution

Air Pollution: Types, sources, primary & secondary pollutants, smog, acid rain, effects, control technologies & policies.

Which city has issued a red alert for air pollution for the first time ever on December, 2015 with a heavy cloud of dangerous smog blanketing the city?
Asked in: APSC CCE Prelims Exam 2016
1. Hong Kong
2. New Delhi
3. Beijing
4. None of the above
Show answer
Answer: C. Beijing
- The red alert is the highest level in Beijing's four- tier alert system for air pollution. - It mandates emergency measures such as closing schools, restricting vehicle use, and halting construction and factory work to reduce pollution.
Which among the following types is a non- material pollution?
Asked in: APSC CCE Prelims Exam 2020
1. Air pollution
2. Water pollution
3. Thermal pollution
4. Soil pollution
Show answer
Answer: C. Thermal pollution
Non-material pollution refers to the presence of excess energy in the environment, such as heat (thermal), noise, or light, rather than the presence of physical substances or chemicals, which characterize material pollution like air, water, and soil pollution.
What is Particulate matter ?
Asked in: BPSC Prelims Exam 60 62rd
1. Solid residue
2. Air pollutant
3. Water pollutant
4. Soil pollutant
Show answer
Answer: B. Air pollutant
PM comes in various sizes, and those smaller than 10 micrometers (PM10) and 2.5 micrometers (PM2.5) are particularly harmful to human health as they can be inhaled deep into the lungs.
Match List-I with List-II and select the correct answer using the codes given below the lists : List-I List-II a. Skin Cancer 1. Chlorofluorocarbons b. Noise Pollution 2. Ultraviolet light c. Global Warming 3. Decibel d. Ozone Hole 4. Carbon dioxide Codes :
Asked in: BPSC Prelims Exam 60 62rd
1. a b c d 1 2 3 4
2. a b c d 2 3 4 1
3. a b c d 2 3 1 4
4. a b c d 4 3 2 1
Show answer
Answer: B. a b c d 2 3 4 1
- Skin cancer is primarily caused by excessive exposure to ultraviolet (UV) radiation, often linked to damage to the ozone layer which filters UV rays. - Noise pollution is measured in decibels (dB). - Global warming is largely driven by the increase in greenhouse gases, with carbon dioxide (CO₂) being the most significant anthropogenic contributor. - The depletion of the ozone layer, leading to the "ozone hole," is caused by ozone-depleting substances, prominently chlorofluorocarbons (CFCs).
Which of the following is present in maximum amount in acid rain ?
Asked in: BPSC Prelims Exam 60 62rd
1. HCl
2. HNO3
3. H2SO4
4. H2CO3
Show answer
Answer: C. H2SO4
- Acid rain is primarily caused by emissions of sulfur dioxide (SO₂) and nitrogen oxides (NOₓ), mainly from burning fossil fuels. - These pollutants react with water, oxygen, and other chemicals in the atmosphere to form sulfuric acid (H₂SO₄) and nitric acid (HNO₃). - While both contribute to acidity, sulfuric acid often accounts for a larger proportion of the acidity, especially in areas heavily impacted by coal combustion.
The incomplete burning of petrol and diesel produces
Asked in: BPSC Prelims Exam 66th
1. nitric oxide
2. nitrogen dioxide
3. carbon dioxide
4. carbon monoxide
Show answer
Answer: D. carbon monoxide
Combustion is a chemical process where a substance reacts rapidly with oxygen to produce heat and light. For hydrocarbons like those in petrol and diesel, complete combustion (with sufficient oxygen) yields carbon dioxide (CO₂) and water (H₂O). However, when there is insufficient oxygen (incomplete combustion), carbon monoxide (CO) is produced instead of carbon dioxide, and sometimes even unburnt carbon particles (soot) are formed. Carbon monoxide is a toxic gas.
Which of the following statements is / are correct ? 1. Acid rain reacts with buildings made from limestone 2. Burning of sulphur containing coal can contribute to acid rain 3. Eutrophication is an effective measure to control pollution Select the correct answer using the code given below :
Asked in: UPSC CDS 1 2016
1. 1 and 2 only
2. 2 and 3 only
3. 1 only
4. 1, 2 and 3
Show answer
Answer: A. 1 and 2 only
Acid rain is corrosive and can damage buildings made of materials like limestone (calcium carbonate) through chemical reaction. Burning fossil fuels containing sulfur, such as coal, releases sulfur dioxide (SO2), which is a major precursor to acid rain. Eutrophication is the process of excessive nutrient enrichment in a water body, often caused by pollution (e.g., nutrient runoff), leading to algal blooms and oxygen depletion; it is a type of pollution, not a method to control it.

Eutrophication: Process, causes, consequences, control measures.

Consider the following statements and choose the right options given below. (1) Presence of large amounts of nutrients in water also causes excessive growth of planktonic (free-floating) algae, called an algal bloom. (2) Algal bloom causes deterioration of water quality and fish mortality.
Asked in: CGPSC Prelims Exam 2023
1. Only the statement (1) is correct
2. Only the statement (2) is correct
3. Both the statements (1) and (2) are in-correct
4. Both the statements (1) and (2) are correct
Show answer
Answer: D. Both the statements (1) and (2) are correct
Eutrophication is a process where increased nutrient levels cause excessive primary production, leading to dense algal blooms. These blooms degrade water quality and can cause oxygen depletion upon decomposition, leading to fish kills.
Dead zones in the world's oceans and large lakes are characterized by :
Asked in: HPPSC HPAS Prelims 2016
1. High biological oxygen demand
2. Excessive bloom of algae
3. Excess nutrients like nitrates and phosphates
4. All of the above
Show answer
Answer: D. All of the above
Dead zones are areas in the ocean or large lakes where oxygen levels are critically low (hypoxia), making it difficult for most marine life to survive. This condition is primarily caused by eutrophication, a process triggered by excess nutrients like nitrates and phosphates entering the water body.
Which of the following statements about Eutrophication is/are correct? (a) The eutrophication occurs in lotic water body primarily in hilly region. (b) The eutrophication occurs in lentic water and there is gradual accumulation of organisms and their products. (c) The eutrophication promotes fish growth as algal blooms serve as source of food to fishes. (d) The eutrophicated water is oxygen rich and safe for human consumption without treatment.
Asked in: MPSC CS Prelims 2013
1. only (a)
2. only (d)
3. (b) and (c)
4. (a) and (d)
Show answer
Answer: C. (b) and (c)
Eutrophication is nutrient enrichment of water bodies, primarily lentic. It leads to algal blooms, accumulation of organic matter, and ultimately oxygen depletion, which is detrimental to aquatic life. While initial increased productivity might support some organisms, the overall effect is negative.
Identify the incorrect statement:
Asked in: OPSC CS Prelims 2021
1. Eutrophication is a natural process seen in fresh water bodies.
2. Greenhouse effect occurs naturally.
3. In the upper part of the atmosphere, ozone causes harm to animals.
4. In tropical areas, most of the forests have been lost.
Show answer
Answer: C. In the upper part of the atmosphere, ozone causes harm to animals.
Statement C is incorrect. Ozone (O₃) exists in different layers of the atmosphere with different effects. In the stratosphere (upper part of the atmosphere), ozone forms the ozone layer, which absorbs most of the sun's harmful ultraviolet (UV) radiation. This protects life on Earth, including animals, from the damaging effects of UV radiation. In the troposphere (lower atmosphere), ozone is a pollutant and can cause respiratory problems and harm vegetation. The statement specifically refers to the upper atmosphere, where ozone is beneficial, not harmful, to animals.
Eutrophication of water body results from
Asked in: RPSC RAS Prelims 2013
1. Depletion of oxygen
2. Enhanced growth of algae or algal blooms
3. High amounts of nitrogenous nutrients and or‐ thophosphates
4. Submersing idols in the water body
Show answer
Answer: C. High amounts of nitrogenous nutrients and or‐ thophosphates
Eutrophication is primarily caused by excessive input of nutrients, particularly nitrogen (in the form of nitrates) and phosphorus (in the form of phosphates), into a water body, often from agricultural runoff, sewage, and industrial waste.
Eutrophication leads to the death of fish due to ______
Asked in: TNPSC CS Prelims 2024
1. Increasing O₂ content
2. Increasing CO₂ content
3. Decreasing Algae content
4. Decreasing O₂ content
Show answer
Answer: D. Decreasing O₂ content
Eutrophication is the process by which an entire body of water, or parts of it, becomes progressively enriched with minerals and nutrients, particularly nitrogen and phosphorus. This often leads to excessive growth of algae (algal blooms). When these large algal blooms die, decomposer bacteria consume the dead organic matter. This decomposition process consumes large amounts of dissolved oxygen in the water, leading to a state of hypoxia (low oxygen) or anoxia (no oxygen). Fish and other aquatic organisms require dissolved oxygen to survive, so the depletion of oxygen leads to their death.
The abundant growth of algae in water reservoirs is due to
Asked in: TNPSC CS Prelims 2024
1. Eutrophication
2. Thermal pollution
3. Bio magnification
4. Radioactive pollution
Show answer
Answer: A. Eutrophication
Eutrophication is the process of nutrient enrichment in a water body, leading to increased primary production (like algal growth). Severe eutrophication can lead to oxygen depletion when algae die and decompose, harming aquatic life.

Indoor Air Pollution: Sources, health effects, control measures.

The most important indoor air pollutant is
Asked in: CGPSC Prelims Exam 2015
1. Sulpher Dioxide
2. Carbon Dioxide
3. Nitrogen Dioxide
4. Radon gas
Show answer
Answer: D. Radon gas
Radon is a naturally occurring radioactive gas that emanates from the decay of uranium in soil and rocks. It can seep into buildings through foundations. Long-term exposure to high levels of radon is a leading cause of lung cancer, particularly for non- smokers. While other pollutants listed are significant, Radon's link to lung cancer makes it a primary concern for indoor air quality, depending on geological factors.
Which of the following causes maximum indoor chemical pollution?
Asked in: JPSC CS Prelims 2021
1. Room spray
2. Burning mosquito coil
3. Burning coal
4. Burning cooking gas
Show answer
Answer: C. Burning coal
Burning solid fuels like coal indoors, especially in poorly ventilated spaces (common in traditional cooking or heating practices), releases a complex mixture of pollutants including high levels of particulate matter (PM2.5 and PM10), carbon monoxide (CO), sulfur dioxide (SO₂), nitrogen oxides (NOx), polycyclic aromatic hydrocarbons (PAHs), and heavy metals. These pollutants cause significant indoor air pollution and pose serious health risks.
The principal threat to organic artefacts at high levels of RH is - - (5) Question not attempted
Asked in: Archaeology and Museums Dept. Exam 2023 (Curator) 2023
1. Crizzling
2. Bronze disease
3. Corrosion
4. Mould growth
Show answer
Answer: D. Mould growth
High relative humidity combined with organic materials creates an ideal environment for mould growth, which can cause severe damage to artefacts such as paper, textiles, and wood.
What should be avoided to prevent dampness in a Record Room? - (5) Question not attempted
Asked in: Department Recruitment 2024 (Research Scholar) 2024
1. Placing water pipes and drain pipes near the Record Room
2. Using LED lights
3. Installing central air conditioning
4. Providing adequate ventilation
Show answer
Answer: A. Placing water pipes and drain pipes near the Record Room
Placing water pipes and drain pipes near the Record Room must be avoided to prevent dampness.
Which one of the following is a major indoor air pollutant in India?
Asked in: ASCO 2014
1. Ozone
2. Peroxy Acetyl Nitrite (PAN)
3. Carbon monoxide
4. Sulphur dioxide
Show answer
Answer: C. Carbon monoxide
HORTICULTURE DEVELOPMENT OF‐ FICER(HDO) -2015 Carbon monoxide is a significant indoor air pollutant in India, often linked to cooking fuels.
Which one of the following is a major indoor air pollutant in India?
Asked in: POST GRADUATE TEACHER (PGT) 2018
1. Ozone
2. Peroxy Acetyl Nitrite (PAN)
3. Carbon monoxide
4. Sulphur dioxide
Show answer
Answer: C. Carbon monoxide
Carbon monoxide is a significant indoor air pollutant in India, largely from household cooking fuels.

Light Pollution: Sources, ecological impacts, mitigation.

Assertion (A): Recommended light level for light sensitive objects is 50 lux. Reason (R): Keeping light sensitive objects under 50 lux eliminates damage from light. - (5) Question not attempted
Asked in: Archaeology and Museums Dept. Exam 2023 (Curator) 2023
1. A is false but R is true.
2. A is true but R is false.
3. Both A and R are individually true and R is the correct explanation of A.
4. Both A and R are individually true but R is not the correct explanation of A.
Show answer
Answer: B. A is true but R is false.
The assertion about the recommended light level for light-sensitive objects being around 50 lux is generally correct as a measure to preserve them. However, the reason that this level eliminates damage is an overstatement and therefore incorrect, as damage is minimized, not completely eradicated.

Marine Pollution: Sources (oil spills, plastics, sewage), impacts, prevention strategies.

According to the United Nations Environment Programme (UNEP), one of the recent large-scale accidental releases of methane gas into the ocean occurred in
Asked in: UPSC Geoscientist 2023
1. Exxon Valdez
2. Nord Stream
3. Deepwater Horizon
4. Atlantic Empress
Show answer
Answer: B. Nord Stream
- In September 2022, leaks were discovered in the Nord Stream 1 and Nord Stream 2 gas pipelines in the Baltic Sea. - These pipelines carried natural gas (primarily methane) from Russia to Europe. The leaks resulted in a massive release of methane into the atmosphere and the surrounding ocean. - UNEP and other organizations reported on the scale and environmental implications of this event, describing it as potentially the largest single release of methane from a single source ever recorded.
Which of the following are the two aims of “Clean Ocean Manifesto” of United Nations? 1. Reducing marine debris by 20-50 per cent 2. Globe circling & high-tech system of monitors 3. Protecting the Arctic and Antarctica from melting and preventing ocean high levels
Asked in: GPSC Prelims CSP 2 2022
1. 1 and 2 only
2. 2 and 3 only
3. 1 and 3 only
4. 1, 2 and 3
Show answer
Answer: A. 1 and 2 only
- Statement 1: Reducing marine debris (especially plastic) is a central goal for numerous initiatives aimed at cleaning the ocean. The specific percentage (20-50%) might refer to a target from a specific, potentially lesser-known, manifesto or proposal, but the goal itself is prominent. - Statement 2: Implementing a comprehensive monitoring system is essential for assessing the state of the ocean, tracking pollution, and evaluating the effectiveness of cleanup efforts. A high-tech, potentially globe- circling, system aligns with the need for robust data collection. - Statement 3: Protecting polar regions and addressing climate change impacts like sea- level rise ("preventing ocean high levels") are crucial for ocean health but fall more under the broader scope of climate action and conservation rather than solely a "Clean Ocean" focus, which often emphasizes pollution and debris. The phrasing "preventing ocean high levels" is also unusual.
The use of microorganism metabolism to remove pollutants such as oil spills in the water bodies is known as :
Asked in: OPSC CS Prelims 2018
1. Biomagnification
2. Bioremediation
3. Biomethanation
4. Bioreduction
Show answer
Answer: B. Bioremediation
Bioremediation is the use of microorganisms (or other biological agents) to clean up environmental pollutants.
What is meant by the term “Oilzapper” that we frequently hear in the news ?
Asked in: PPSC CS Prelims 2018
1. It is an eco-friendly technology for the remedi‐ ation of oily sludge and oil spills.
2. It is the latest technology developed for under- sea oil exploration.
3. It is a genetically engineered high biofuel- yielding maize variety.
4. It is the latest technology to control the accidentally caused flames from oil wells.
Show answer
Answer: A. It is an eco-friendly technology for the remedi‐ ation of oily sludge and oil spills.
Oilzapper is a cocktail of five different bacterial strains (a consortium) developed by The Energy and Resources Institute (TERI) in India. These bacteria are immobilized and mixed with a carrier material like sawdust. When applied to oily waste or spills, these 'oleophilic' bacteria consume the hydrocarbons, converting them into harmless carbon dioxide and water. It is a form of bioremediation.
Read the following and choose the correct statement(s) : The Pacific nation of Palau became the first country to ban "Coral reef-toxic" sunscreens. Chemicals like oxybenzone and octinoxate that are present in most of the sunscreens, absorb UV light and are thus harmful to the Corals. Choose the correct option :
Asked in: PPSC CS Prelims 2021
1. Only 1
2. Only 2
3. Both 1 and 2
4. Neither 1 nor 2
Show answer
Answer: C. Both 1 and 2
- Statement 1: Palau indeed became the first country in the world to ban "coral reef-toxic" sunscreens. The ban came into effect on January 1, 2020, targeting specific chemicals found in sunscreens that are harmful to marine life, particularly corals. This statement is true. - Statement 2: Chemicals such as oxybenzone (also known as benzophenone-3) and octinoxate (also known as octyl methoxycinnamate) are common ingredients in chemical sunscreens that absorb UV light. Research has shown that these chemicals can cause coral bleaching, DNA damage, and deformities in coral larvae. This statement is true.
Estuaries possess distinct blooms of excessive growth of a pigmented dinoflagellate. These blooms are called
Asked in: UPPCS Prelims 1998
1. red tides
2. sea tides
3. black tides
4. sea flowers
Show answer
Answer: A. red tides
Excessive growth of pigmented dinoflagellates or other algae in aquatic ecosystems is commonly referred to as an algal bloom. When these blooms are dense and caused by certain types of algae with pigments (often red, brown, or green), they can discolor the water. The term "red tide" specifically refers to harmful algal blooms caused by dinoflagellates that can produce toxins and cause the water to appear reddish or brownish. These often occur in coastal areas, including estuaries, where nutrient runoff can fuel their growth.
The name Amoco Cadiz is related with
Asked in: WBCS Main Paper 4 2021
1. Nuclear waste site
2. Oil slick
3. Toxic cloud
4. Forest fire
Show answer
Answer: B. Oil slick
The Amoco Cadiz spill was one of the most significant marine pollution incidents in history, causing immense ecological and economic damage to the French coastline.

Noise Pollution: Sources, impacts on health & wildlife, permissible limits, mitigation.

Temporary threshold shift (TTS) is temporary hearing loss often caused by 1. Air pollution 2. Water pollution 3. Noise pollution 4. Land pollution Select the correct answer using the code given below:
Asked in: GPSC Prelims CSP 2 2023
1. 1 only
2. 3 only
3. 3 and 4
4. 4 only
Show answer
Answer: B. 3 only
Temporary Threshold Shift (TTS) is a temporary decrease in hearing sensitivity that occurs after exposure to a loud noise. It is a direct physiological response of the auditory system to excessive sound pressure levels.
In the context of permissible noise level match List-I with List-II and select the answer from the code given below the lists. List-I List-II (Area) (Permissible Noise Level)
Asked in: UPPCS Prelims 2022
1. Residential area 1. 50 db
2. Silent zone 2. 55 db
3. Industrial area 3. 65 db
4. Commercial area 4. 70 db Code: A. (a) 2, (b) 1, (c) 3, (d) 4 B. (b) 3, (a) 4, (c) 2, (d) 1 C. (c) 2, (b) 1, (a) 4, (d) 3 D. (d) 1, (a) 2, (b) 3, (c) 4
Show answer
Answer: A. Residential area 1. 50 db
- Standard permissible noise levels vary by zone (Industrial, Commercial, Residential, Silent) and time of day (Day/Night). - Typical daytime limits: Silent Zone (50 dB), Residential (55 dB), Commercial (65 dB), Industrial (75 dB).
Green Muffler is
Asked in: UPSC CAPF 2012
1. a technology for reducing air pollution
2. a method of afforestation
3. plantation along roadsides to reduce noise pol‐ lution
4. a process of reducing vibration
Show answer
Answer: C. plantation along roadsides to reduce noise pol‐ lution
The term "Green Muffler" refers to the concept of using trees and shrubs planted in strategic locations, often in multiple rows along roads, highways, and industrial areas, to absorb and dissipate sound waves, thereby reducing noise pollution. The dense foliage acts as a barrier and a sound-absorbing medium.
Noise pollution is created if noise is in excess to
Asked in: WBPSC CS Prelims 2019
1. 70-75 dB
2. 50-60 dB
3. 80-99 dB
4. 40-65 dB
Show answer
Answer: C. 80-99 dB
Different decibel levels have different impacts: - Below 70 dB: Generally considered safe and not harmful. - 70-80 dB: Can be annoying or disruptive, especially with continuous exposure. - Above 80-85 dB: Risk of hearing damage increases significantly with exposure time. - Above 120 dB: Can cause immediate pain and irreversible hearing damage. The range 80-99 dB clearly falls into the category of noise levels associated with pollution and potential harm, especially in urban environments or industrial settings.
Sound above what level (decibels) are considered hazardous noise pollution?
Asked in: UPPSC Upper Mains 2008
1. 30 dB
2. l00dB
3. 80 dB
4. 120 dB
Show answer
Answer: C. 80 dB
While higher levels are also hazardous, prolonged exposure to sound levels above 80 decibels is generally considered the threshold at which there is a risk of noise-induced hearing damage.
As per the WHO the safe noise level for a city is
Asked in: UPPSC Upper Mains 2010
1. 45 db
2. 50 db
3. 55 db
4. 60 db
Show answer
Answer: C. 55 db
According to the World Health Organization (WHO) guidelines on community noise, the recommended noise level for outdoor living areas in residential zones to prevent serious annoyance during the daytime is 55 dB(A).
What type of noise can be abated by providing lining on walls and ceiling with sound absorbing material?
Asked in: WBCS Main Paper 4 2022
1. Source noise
2. Air borne noise
3. Structural noise
4. Reflection noise
Show answer
Answer: B. Air borne noise
- Air borne noise travels through the air. When it hits surfaces like walls and ceilings, it can be reflected, absorbed, or transmitted. - Sound-absorbing materials reduce the amount of sound energy reflected back into the room, thereby reducing reverberation and overall noise levels from sources within the space. - Source noise is the noise generated directly by the source itself. Abatement at the source involves modifying the equipment or process. - Structural noise (or structure-borne noise) travels through the building structure (walls, floors, etc.). Abatement involves isolating the source from the structure or using damping materials. - "Reflection noise" is not a standard term; reflections are a part of how air borne noise propagates in a room.

Persistent Organic Pollutants (POPs) and Heavy Metal Pollution: Characteristics, sources, biomagnification, effects, relevant conventions.

Methyl Isocyanate gas, which was involved in the disaster in Bhopal in December 1984, was used in the Union Carbide factory for production of :
Asked in: UPSC CDS 1 2016
1. Dyes
2. Detergents
3. Explosives
4. Pesticides
Show answer
Answer: D. Pesticides
The Union Carbide India Limited (UCIL) plant in Bhopal produced the pesticide Carbaryl, marketed under the brand name Sevin. Methyl Isocyanate (MIC) was a key intermediate chemical used in the synthesis of Carbaryl. The disaster occurred due to a leak of MIC gas from the plant.
Statement I : Bioaccumulation is a process of progressive accumulation of heavy metals and pesticides in an organism. Statement II : Large fishes of the pond are found to have higher concentration of pesticides than planktons of the same pond.
Asked in: UPSC CDS 1 2018
1. Option text is missing in the image.
2. Option text is missing in the image.
3. Option text is missing in the image.
4. Option text is missing in the image.
Show answer
Answer: B. Option text is missing in the image.
Bioaccumulation is the accumulation within one organism. Biomagnification is the increase in concentration of a substance as it moves up the food chain.
Who is the author of the book "Silent Spring" ?
Asked in: CGPSC Prelims Exam 2019
1. Eugene P. Odum
2. Rachel Carson
3. James Lyons-Weiler
4. E.O. Wilson
Show answer
Answer: B. Rachel Carson
Published in 1962, "Silent Spring" documented the detrimental effects on the environment of the indiscriminate use of pesticides, particularly DDT. It is widely credited with launching the modern environmental movement.
Mercury is a toxic substance that severely contaminates land, water, air and the food chain. Which among the following is/are source(s) of mercury pollution? I. Pesticides II. Dental amalgam fillings III. Fluorescent lamp IV. Coal-based thermal power plants
Asked in: CGPSC Prelims Exam 2020
1. Only I
2. Only I and II
3. Only I, II and III
4. I, II, III and IV all
Show answer
Answer: D. I, II, III and IV all
Mercury is a persistent, bioaccumulative, and toxic substance. Anthropogenic sources contribute significantly to its presence in the environment. I. Pesticides: Historically, some pesticides contained mercury compounds. II. Dental amalgam fillings: These are a common source of mercury exposure and release. III. Fluorescent lamps: Contain mercury vapor which is released upon breakage or improper disposal. IV. Coal-based thermal power plants: Burning coal is a major source of atmospheric mercury emissions.
The term Biomagnification refers to :
Asked in: HPPSC HPAS Prelims 2010
1. raising of environmental issues by man
2. growth of organism due to food consumption
3. increase in population size
4. increase in concentration of non-biodegradable pollutants
Show answer
Answer: D. increase in concentration of non-biodegradable pollutants
- Biomagnification involves the accumulation of substances in organisms. - The concentration increases as one moves up the trophic levels in a food chain. - The substances involved are typically non- biodegradable or slowly biodegradable pollutants (e.g., heavy metals like mercury, persistent organic pollutants like DDT).
India ratified the Stockholm Convention for protecting human health and the environment from persistent organic pollutants in :
Asked in: HPPSC HPAS Prelims 2016
1. 2005
2. 2006
3. 2002
4. 2010
Show answer
Answer: B. 2006
- The Stockholm Convention on Persistent Organic Pollutants (POPs) is an international environmental treaty, signed in 2001 in Stockholm and effective from 2004. - The convention aims to eliminate or restrict the production and use of POPs. - India ratified the Stockholm Convention on January 13, 2006.
हमेशा रहने वालिे प्रदूषिकों से मानव स्वास्थ्य और पयार्मावरण की सुरक्षा के ͧलिए भिारत ने स्टिॉकहोम सम्मेलिन में संशोधन कब ͩकया ?
Asked in: HPPSC HPAS Prelims 2016
1. 2005
2. 2006
3. 2002
4. 2010
Show answer
Answer: B. 2006
- The Stockholm Convention aims to eliminate or restrict the production and use of Persistent Organic Pollutants (POPs). - India ratified the convention in 2006.

Plastic Pollution & Microplastics: Sources, ecological & health impacts, management strategies.

Which of the following groups contains/ contain only non-biodegradable materials? (i) Wood, paper, leather (ii) Plastic, bakelite, DDT (iii) Plastic, thermocol, wood (iv) Thermocol, plates made from dried leaves, detergents Select the correct answer using the codes given below.
Asked in: APSC CCE Prelims Exam 2023
1. (i) and (ii) only
2. (ii) only
3. (ii) and (iii) only
4. (iii) and (iv) only
Show answer
Answer: B. (ii) only
- Biodegradable materials decompose naturally through biological processes. - Non-biodegradable materials persist in the environment for long periods. - Plastics, certain synthetic chemicals (like DDT), and some detergents are examples of non- biodegradable materials. - Natural materials like wood, paper, and leather are typically biodegradable.
The use of plastics has led to a number of environment-related problems. For this, which one of the following statements is correct?
Asked in: UPSC CDS 1 2024
1. They are non-biodegradable.
2. They do not get released into water and food.
3. They do not have any biochemical synthesis activity.
4. They are harmless to humans.
Show answer
Answer: A. They are non-biodegradable.
Plastics are non-biodegradable and accumulate in the environment, leading to pollution of land, water, and air.
As per Plastic Wastes (Management & Handling) Rules, 2011 manufacturing of plastic bags less than _____ thickness is banned.
Asked in: KPSC KAS Prelims 2014
1. 25 microns
2. 30 microns
3. 35 microns
4. 40 microns
Show answer
Answer: D. 40 microns
The 2011 rules set the minimum thickness limit for plastic bags at 40 microns.
Which of the commonly used household item(s) release Bisphenol A (BPA) which is an endocrine disruptor and bad for human health? 1. Steel utensils 2. Plastic coffee mugs 3. Aluminium utensils 4. Plastic water storage bottles Select the correct answer using the code given below:
Asked in: UPSC NDA 1 2016
1. 1 only
2. 1 and 2 only
3. 2 and 4 only
4. 1, 2 and 3 only
Show answer
Answer: C. 2 and 4 only
Bisphenol A (BPA) is a chemical used in the production of polycarbonate plastics and epoxy resins. Polycarbonate plastic is commonly used in making hard plastic items like reusable water bottles and some coffee mugs. Epoxy resins are often used as internal coatings for food and beverage cans and metal lids.
Which of the following material is bio-degradable?
Asked in: UPPCS Prelims 2022
1. Glass bottle
2. Plastic cups
3. Aluminium foil
4. Wool
Show answer
Answer: D. Wool
Biodegradable materials decompose naturally over time, unlike non-biodegradable materials such as most plastics, glass, and metals which persist in the environment for very long periods.
Directions : Each of the next FIVE (05) items consists of two statements, one labelled as the Assertion (A) and the other as ‘Reason (R)’. You are to examine these two statements carefully and select the answers to these items using the codes given below : Codes : Assertion (A) : Import of Chinese toys was recently banned by the Government of India. Reason (R) : The plastic material used to make the toys are not biodegradable.
Asked in: UPSC CAPF 2009
1. Both A and R are individually true and R is the correct explanation of A
2. Both A and R are individually true but R is not the correct explanation of A
3. A is true but R is false
4. A is false but R is true
Show answer
Answer: B. Both A and R are individually true but R is not the correct explanation of A
- Assertion (A) states that the import of Chinese toys was recently banned by the Government of India. This is a factual statement that aligns with events that occurred around 2009 when India imposed a temporary ban on certain toy imports from China. - Reason (R) states that the plastic material used to make the toys is not biodegradable. This is generally true; many types of plastic commonly used in toys are not biodegradable. - However, the primary reason cited by the Government of India for the ban on Chinese toys was not their non-biodegradability, but rather concerns about safety and quality standards, specifically high levels of lead and other toxic chemicals hazardous to children's health. - Therefore, while both statements are individually true, the non-biodegradability of the plastic was not the reason for the import ban. R is not the correct explanation for A.
Why is there a great concern about the 'microbeads' that are released into environment?
Asked in: UPSC IAS 2019
1. They are considered harmful to marine ecosys‐ tems.
2. They are considered to cause skin cancer in children.
3. They are small enough to be absorbed by crop plants in irrigated fields.
4. They are often found to be used as food adul‐ terants.
Show answer
Answer: A. They are considered harmful to marine ecosys‐ tems.
Microbeads are tiny plastic particles, typically less than 5 mm in diameter, used in various products like cosmetics, toothpastes, and abrasive cleaners. When washed down drains, they enter wastewater systems but are often too small to be filtered out. They are then released into rivers, lakes, and oceans. Once in aquatic environments, microbeads persist for a very long time and pose a significant threat to marine life.

Radioactive Pollution: Sources, health & environmental impacts, waste management.

The most dangerous radioactive pollutant among the following is
Asked in: KPSC KAS Prelims 2024
1. phosphorous-32
2. strontium-90
3. calcium-40
4. sulphur-32
Show answer
Answer: B. strontium-90
The danger of a radioactive pollutant depends on its half-life, the type of radiation emitted, its activity, and how it is absorbed and retained by the body. Isotopes that mimic essential elements (like Strontium mimicking Calcium, or Iodine mimicking Iodine) and are retained for long periods in critical tissues are particularly hazardous.
IAEA looks after the safety for which type of pollution?
Asked in: WBCS Main Paper 4 2023
1. Heavy Metals
2. Hydro carbon
3. Plastic
4. Radio active elements
Show answer
Answer: D. Radio active elements
The IAEA's mandate includes establishing safety standards, verifying the peaceful use of nuclear material, and promoting nuclear safety and security.

Soil Pollution: Causes, effects (contamination, degradation), remediation techniques.

Which post-emergence herbicide is used for controlling parasitic cuscutta weed in lucern crop ?
Asked in: MPSC CS Prelims 2012
1. Paraquat
2. Chlorpropham
3. Alachlor
4. Pronamide
Show answer
Answer: B. Chlorpropham
Cuscuta (dodder) is a parasitic weed that can severely damage lucerne crops. Selecting a herbicide that controls the parasite without harming the host crop is crucial.
Which of the following is an example of herbicide?
Asked in: UPPCS Prelims 2019
1. Sodium chlorate
2. Potassium permanganate
3. Bleaching powder
4. None of the above
Show answer
Answer: A. Sodium chlorate
- Herbicides are substances used to kill plants (weeds). - Sodium chlorate is a known chemical herbicide. - Potassium permanganate and bleaching powder are primarily disinfectants.
Which of the following is not a biodegradable polluter?
Asked in: UPPCS Prelims 2023
1. Faecal matter
2. Urine
3. Domestic waste
4. Pesticide
Show answer
Answer: D. Pesticide
Biodegradable substances can be broken down by nature, while non-biodegradable substances persist. Pesticides are typically synthetic and non-biodegradable or slowly biodegradable.
The process of using microbes to treat areas of land or sea that have been contaminated by pesticides, oil or solvents is known as :
Asked in: UPSC CAPF 2016
1. Eutrophication
2. Nitrification
3. Ammonification
4. Bioremediation
Show answer
Answer: D. Bioremediation
- Bioremediation utilizes the natural metabolic capabilities of microorganisms to degrade, transform, or immobilize contaminants in soil, water, or air. - It is an environmentally friendly approach compared to some physical or chemical cleanup methods. - Examples include using bacteria to break down oil spills or industrial solvents.
In the context of solving pollution problems, what is/are the advantage/advantages of bioremediation technique? 1. It is a technique for cleaning up pollution by enhancing the same biodegradation process that occurs in nature. 2. Any contaminant with heavy metals such as cadmium and lead can be readily and completely treated by bioremediation using microorganisms. 3. Genetic engineering can be used to create microorganisms specifically designed for bioremediation. Select the correct answer using the code given below:
Asked in: UPSC IAS 2017
1. 1 only
2. 2 and 3 only
3. 1 and 3 only
4. 1, 2 and 3
Show answer
Answer: C. 1 and 3 only
Bioremediation is a waste management technique that uses organisms, primarily microorganisms, to neutralize pollutants in a contaminated site by degrading them into less toxic or non-toxic substances. Genetic engineering can enhance the capabilities of these microorganisms for specific bioremediation tasks.
Which of the following is/are the possible consequence/s of heavy sand mining in riverbeds ? Consider the following statements: Decreased salinity in the river Pollution of groundwater Lowering of the water-table Select the correct answer using the code given below:
Asked in: UPSC IAS 2018
1. 1 only
2. 2 and 3 only
3. 1 and 3 only
4. 1, 2 and 3
Show answer
Answer: B. 2 and 3 only
Let's evaluate each statement: 1. Decreased salinity in the river Heavy sand mining typically impacts the physical structure of the riverbed and flow dynamics, and potentially groundwater interaction. It does not directly cause a decrease in salinity in the river water itself. In coastal areas, it might affect the balance between freshwater and saltwater, potentially leading to increased saltwater intrusion rather than decreased salinity in river areas influenced by tides. This statement is incorrect. 2. Pollution of groundwater Sand and gravel in a riverbed act as a natural filter, helping to purify water as it infiltrates into the groundwater system. Heavy sand mining removes this protective layer, making the groundwater aquifer more vulnerable to contamination from surface pollutants (like agricultural runoff, industrial waste, sewage). This statement is correct. 3. Lowering of the water-table Riverbeds are often hydraulically connected to the surrounding groundwater table. Removing large quantities of sand from the riverbed lowers the base level of the river and disrupts this connection. This can lead to a corresponding drop in the groundwater table in adjacent areas, affecting wells and vegetation that rely on shallow groundwater. This statement is correct.
With reference to agricultural soils, consider the following statements : A high content of organic matter in soil drastically reduces its water holding capacity. Soil does not play any role in the sulphur cycle. Irrigation over a period of time can contribute to the salinization of some agricultural lands. Which of the statements given above is/are correct ?
Asked in: UPSC IAS 2018
1. 1 and 2 only
2. 3 only
3. 1 and 3 only
4. 1, 2 and 3
Show answer
Answer: B. 3 only
Let's evaluate each statement: 1. A high content of organic matter in soil drastically reduces its water holding capacity This statement is incorrect. Organic matter is like a sponge; it significantly increases the soil's ability to absorb and retain water. Soils with high organic matter content hold much more water than soils with low organic matter. 2. Soil does not play any role in the sulphur cycle This statement is incorrect. Soil plays a vital role in the sulphur cycle. It is a major reservoir for sulphur, primarily in organic form. Microorganisms in the soil are essential for the transformation of sulphur compounds (e.g., decomposition of organic matter releasing sulphate, oxidation and reduction reactions of sulphur compounds). Plant uptake of sulphate from the soil is also a key part of the cycle.

Solid Waste Management: Types of waste (municipal, industrial, hazardous, e-waste), collection, treatment, disposal, policies.

The international convention on the control of transboundary movement of hazardous waste and their disposal in order to protect human health and the environment against the adverse effects of hazardous waste is called
Asked in: APSC CCE Prelims Exam 2022
1. Stockholm Convention
2. Basel Convention
3. Minamata Convention
4. Rotterdam Convention
Show answer
Answer: B. Basel Convention
The Basel Convention aims to protect human health and the environment from the adverse effects of hazardous wastes. It regulates the transboundary movements of hazardous wastes and requires their environmentally sound management.
Biodegradable wastes can usually be converted into useful substance with the help of
Asked in: BPSC Prelims Exam 67th Cancelled
1. bacteria
2. viruses
3. nuclear proteins
4. radioactive substances
Show answer
Answer: A. bacteria
Decomposition of organic matter is largely carried out by bacteria and fungi.
The 'Basel Convention' is aimed at protecting human health and environment against adverse effects of which of the following?
Asked in: UPSC CDS 1 2020
1. Hazardous wastes
2. Persistent Organic Pollutants (POPs)
3. Mercury
4. Chemicals and pesticides
Show answer
Answer: A. Hazardous wastes
- Basel Convention regulates the transboundary movement of hazardous wastes and other wastes. - It requires prior informed consent for such movements. - It promotes environmentally sound management of hazardous wastes.
Which one of the following gases is released mostly from landfills in urban areas?
Asked in: UPSC CDS 2 2016
1. Nitrogen
2. Hydrogen
3. Methane
4. Oxygen
Show answer
Answer: C. Methane
Landfills are significant sources of landfill gas, which is produced by the anaerobic decomposition of organic solid waste. The primary components of landfill gas are methane (CH4) and carbon dioxide (CO2). While CO2 is also released, methane is often present in high concentrations (typically 40-60%) and is a potent greenhouse gas.
According to the Solid Waste Management Rules, 2016, the responsibility of waste generators has been fixed for segregation of waste in which of the following streams?
Asked in: UPSC Geoscientist 2023
1. Biodegradable and non-biodegradable wastes
2. Metallic and non-metallic wastes
3. Wet, dry and domestic hazardous wastes
4. Recyclable and non-recyclable wastes
Show answer
Answer: C. Wet, dry and domestic hazardous wastes
- The Solid Waste Management Rules, 2016, mandate segregation of waste at source by the waste generator. - The specified streams for segregation at the household level are typically biodegradable (wet) waste, non-biodegradable (dry) waste, and domestic hazardous waste (like batteries, expired medicines, etc.).
Which of the following are the main contributors of the e-waste in the world? 1. Refrigerators/freezers, washing machines, dishwashers 2. Small household appliances (toasters, coffee makers, irons, hair dryers) 3. Personal computers, telephones, mobile phones, laptops, printers, scanners, photocopiers 4. Gas cylinder, chimneys & home appliances
Asked in: GPSC Prelims CSP 2 2024
1. Only 1, 2, 3
2. Only 1, 2
3. Only 1, 3, 4
4. All of the above
Show answer
Answer: A. Only 1, 2, 3
- E-waste consists of discarded electrical and electronic equipment (EEE). - 1. Refrigerators/ freezers, washing machines, dishwashers: These are categories of Large Household Appliances (White Goods), which are major contributors to e-waste by weight. - 2. Small household appliances (toasters, coffee makers, irons, hair dryers): These form a significant category of e-waste, contributing a large number of units discarded annually. - 3. Personal computers, telephones, mobile phones, laptops, printers, scanners, photocopiers: These are IT and Telecommunications Equipment, representing another major category of e-waste, high in volume and often containing valuable materials and hazardous substances. - 4. Gas cylinder, chimneys & home appliances: Gas cylinders and chimneys are not typically classified as e-waste unless they contain electronic components (which is not the primary function). While "home appliances" in general are e-waste (covered in 1 and 2), the inclusion of non- EEE items makes this category as a whole not a main contributor of e-waste. Therefore, item 4 is not entirely correct as a category of main e-waste contributors.
The global agreement that deals with the control of transboundary movements of hazardous wastes and their disposal is called :
Asked in: HPPSC HPAS Prelims 2016
1. Basel Convention
2. Convention on Early Notification of a Nuclear Accident
3. International Convention for the Prevention of Pollution from Ships
4. Cartagena Protocol on Biosafety
Show answer
Answer: A. Basel Convention
- The convention regulates the transboundary movement of hazardous wastes. - It requires prior informed consent before waste can be shipped from one country to another. - It promotes the environmentally sound management of hazardous wastes.

Thermal Pollution: Sources, impacts on aquatic ecosystems, control.

Thermal pollution which involves release of excessive amounts of heated water in aquatic systems is harmful. It is because hot water:
Asked in: UPSC Geoscientist 2020
1. kills aquatic plants.
2. causes oxygen starvation.
3. kills aquatic microbes.
4. causes CO₂ depletion.
Show answer
Answer: B. causes oxygen starvation.
- Solubility of gases in water decreases as temperature increases. Therefore, less oxygen can dissolve in hot water. - Higher water temperatures increase the metabolic rates of fish and other aquatic organisms, which increases their demand for oxygen. - The combined effect of reduced oxygen availability and increased oxygen demand can lead to stress, suffocation, and death of aquatic life.
Thermal pollution is:
Asked in: UPSC Geoscientist 2021
1. discharge of waste heat into the atmosphere or ocean from increasing use of energy.
2. atmospheric warming due to emission of green house gasses.
3. heat waves during extreme summer.
4. heat trapped in the atmosphere due to dust storm.
Show answer
Answer: A. discharge of waste heat into the atmosphere or ocean from increasing use of energy.
It specifically refers to the release of waste heat from human activities into the environment.

Water Pollution: Sources, common pollutants, water quality indicators (BOD, COD, DO), effects, control measures.

Excessive use of which of the following fertilizers may be responsible for the presence of a toxic substance in groundwater?
Asked in: UPSC CDS 2 2016
1. Nitrogen
2. Phosphate only
3. Potassium only
4. Phosphate and potassium
Show answer
Answer: A. Nitrogen
Nitrates are highly soluble and negatively charged, making them mobile in soil water and susceptible to leaching, especially in well-drained soils and areas with high rainfall or irrigation. Elevated levels of nitrates in drinking water are a human health concern, particularly for infants, as nitrates can be converted to nitrites in the digestive system, interfering with the blood's oxygen-carrying capacity (causing methemoglobinemia). Phosphates are generally less mobile in soil due to adsorption to soil particles. Potassium is also relatively mobile but does not pose the same level of direct toxicity risk in drinking water as nitrates at common concentrations.
Which one of the following statements is not correct?
Asked in: UPSC CDS 2 2016
1. Centre for Science and Environment in a recent study found that a number of commonly available brands of prepackaged breads tested positive for potassium bromate and potassium iodate.
2. Food Safety and Standards Authority of India recommended to the Health Ministry to remove potassium bromate from the list of permissible food additives.
3. The Union Government banned the use of po‐ tassium bromate as a food additive on the basis of the above recommendation.
4. Potassium bromate is a neurotoxin.
Show answer
Answer: D. Potassium bromate is a neurotoxin.
Potassium bromate was identified as a potential health hazard (specifically, a potential carcinogen) when used as a food additive, leading to its ban in India.
The biological oxygen demand (BOD) of unpolluted river water is:
Asked in: UPSC Geoscientist 2020
1. 10 - 20 mg O₂/dm³/5 day.
2. 5-10 mg O₂/dm³/5 day.
3. less than 5 mg O₂/dm³/5 day.
4. more than 20 mg O₂/dm³/5 day.
Show answer
Answer: C. less than 5 mg O₂/dm³/5 day.
- BOD is a key indicator of water quality, reflecting the amount of biodegradable organic pollution. - It is measured over a specific period, usually 5 days (BOD₅) at a standard temperature (20°C). - Lower BOD values indicate better water quality with less organic pollution.
As per the safe drinking water guidelines issued by the Bureau of Indian Standards, Government of India, what is the acceptable pH value of drinking water? Ans: B pH is a measure of how acidic or basic water is. A pH of 7 is neutral. Values below 7 indicate acidity, and values above 7 indicate alkalinity. Maintaining pH within the acceptable range is important for water potability and preventing corrosion in pipes. 337. Sewage treatments generally involve _____. 1. Algal-bacterial symbiosis 2. Photosynthetic oxygenation 3. Biodegradation of organic matter 4. Ex-situ bioleaching
Asked in: UPSC Geoscientist 2022 · GPSC Prelims CSP 2 2022
1. 1 and 2 only
2. 2 and 3 only
3. 1, 2, and 3 only
4. 1, 2, 3 and 4
Show answer
Answer: C. 1, 2, and 3 only
Biological sewage treatment relies on microbial activity to break down organic pollutants, often involving processes like biodegradation and, in some systems, symbiotic relationships leading to photosynthetic oxygenation.
Which of the following statements is/are correct? 1. Disease causing agents include protozoa and parasitic worms 2. Escherichia coli normally grows in the large intestine of human beings 3. Water soluble radioactive isotopes don't create water pollution
Asked in: GPSC Prelims CSP 2 2022
1. 1 only
2. 1 and 2 only
3. 1 and 3 only
4. 1, 2 and 3
Show answer
Answer: B. 1 and 2 only
- Statement 1 is correct. Disease-causing agents, known as pathogens, include various types of organisms. Protozoa (single-celled eukaryotes) like Plasmodium (malaria) and Entamoeba histolytica (amoebiasis), and parasitic worms (helminths) like tapeworms (Taenia), roundworms (Ascaris), and flukes are well-known causes of diseases in humans and animals. - Statement 2 is correct. Escherichia coli is a bacterium that is a normal inhabitant of the lower intestine of warm-blooded animals, including humans. It plays a role in food digestion and produces some vitamins. While some strains of E. coli are pathogenic and can cause food poisoning, the vast majority are harmless and part of the normal gut flora. - Statement 3 is incorrect. Water- soluble radioactive isotopes are a significant source of water pollution. When dissolved in water, they contaminate the water supply, making it hazardous for consumption and other uses. Ingesting radioactive isotopes can lead to internal radiation exposure, causing damage to tissues and increasing the risk of cancer.
Which of the following statements is correct?
Asked in: GPSC Prelims CSP 2 2022
1. Dissolved oxygen of a water body is expected to be high when its temperature is low
2. Dissolved oxygen of a water body is expected to be high when its temperature is high
3. Dissolved oxygen of a water body is expected to be low when its temperature is low
4. Dissolved oxygen of a water body is inde‐ pendent of its temperature
Show answer
Answer: A. Dissolved oxygen of a water body is expected to be high when its temperature is low
Solubility of gases in water is inversely proportional to temperature. As water temperature decreases, the solubility of oxygen increases, meaning more oxygen can dissolve in the water. Conversely, as temperature increases, the solubility of oxygen decreases.
Central Pollution Control Board is primarily responsible for 1. Controlling river pollution in our country 2. Monitoring air pollution 3. Sewage disposal and effluent treatment guidelines 4. Publishing data and statistics related to air and water pollution. Select the correct answer using the code given below:
Asked in: GPSC Prelims CSP 2 2023
1. 1 only
2. 1 and 2
3. 1, 2 and 3
4. 1, 2, 3 and 4
Show answer
Answer: D. 1, 2, 3 and 4
The Central Pollution Control Board (CPCB) is a statutory organization under the Ministry of Environment, Forest and Climate Change, established under the Water (Prevention and Control of Pollution) Act, 1974, and also entrusted with the powers and functions under the Air (Prevention and Control of Pollution) Act, 1981. Its broad functions include promoting the cleanliness of streams and wells, improving the quality of air, preventing, controlling or abating pollution.

Air Pollution: Types, sources, primary & secondary pollutants, smog, acid rain, effects, control technologies & policies.

Eutrophication: Process, causes, consequences, control measures.

Indoor Air Pollution: Sources, health effects, control measures.

Light Pollution: Sources, ecological impacts, mitigation.

Marine Pollution: Sources (oil spills, plastics, sewage), impacts, prevention strategies.

Noise Pollution: Sources, impacts on health & wildlife, permissible limits, mitigation.

Persistent Organic Pollutants (POPs) and Heavy Metal Pollution: Characteristics, sources, biomagnification, effects, relevant conventions.

conventions.

Plastic Pollution & Microplastics: Sources, ecological & health impacts, management strategies.

Radioactive Pollution: Sources, health & environmental impacts, waste management.

Soil Pollution: Causes, effects (contamination, degradation), remediation techniques.

Solid Waste Management: Types of waste (municipal, industrial, hazardous, e-waste), collection, treatment, disposal, policies.

Thermal Pollution: Sources, impacts on aquatic ecosystems, control.

Water Pollution: Sources, common pollutants, water quality indicators (BOD, COD, DO), effects, control measures.

10. Water Conservation

Practice MCQs: Pollution

Air Pollution: Types, sources, primary & secondary pollutants, smog, acid rain, effects, control technologies & policies.

Eutrophication: Process, causes, consequences, control measures.

Indoor Air Pollution: Sources, health effects, control measures.

Light Pollution: Sources, ecological impacts, mitigation.

Marine Pollution: Sources (oil spills, plastics, sewage), impacts, prevention strategies.

Noise Pollution: Sources, impacts on health & wildlife, permissible limits, mitigation.

Persistent Organic Pollutants (POPs) and Heavy Metal Pollution: Characteristics, sources, biomagnification, effects, relevant conventions.

Plastic Pollution & Microplastics: Sources, ecological & health impacts, management strategies.

Radioactive Pollution: Sources, health & environmental impacts, waste management.

Soil Pollution: Causes, effects (contamination, degradation), remediation techniques.

Solid Waste Management: Types of waste (municipal, industrial, hazardous, e-waste), collection, treatment, disposal, policies.

Thermal Pollution: Sources, impacts on aquatic ecosystems, control.

Water Pollution: Sources, common pollutants, water quality indicators (BOD, COD, DO), effects, control measures.

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