Last reviewed 16 Sept 2026 · Facts as of 16 Sept 2026 · 10 min read
Environment and ecosystems
- Environment — surroundings of living organisms: abiotic (air, water, soil, climate) and biotic (plants, animals, microorganisms) components.
- Ecosystem — interacting community of organisms and their physical environment; energy flows (producers → consumers → decomposers) and nutrients cycle (carbon, nitrogen, water).
- Ecological balance is disturbed by pollution and overexploitation.
Pollution
Pollution — introduction of harmful substances or energy into the environment causing adverse effects. Pollutants may be primary (emitted directly, e.g. SO₂) or secondary (formed in the atmosphere, e.g. ozone); biodegradable (sewage) or non-biodegradable (plastics, heavy metals).
Air pollution
| Aspect | Details |
|---|---|
| Sources | Vehicles, thermal power plants, industries (cement, steel, brick kilns), construction and demolition dust, road dust, crop residue burning, domestic fuel burning, waste burning |
| Major pollutants | PM₁₀, PM₂.₅, SO₂, NOx, CO, ground-level O₃, NH₃, lead, benzene, VOCs |
| Effects | Respiratory and cardiovascular diseases, reduced visibility (smog), acid rain, damage to crops and buildings (e.g. marble corrosion) |
| Control | Cleaner fuels (BS-VI norms), electric vehicles, public transport, electrostatic precipitators, bag filters, scrubbers, flue gas desulphurisation, dust suppression on construction sites (water sprinkling, covering materials, wind barriers), ban on open burning, green belts |
National Air Quality Index (AQI) categories:
| AQI | Category |
|---|---|
| 0–50 | Good |
| 51–100 | Satisfactory |
| 101–200 | Moderate |
| 201–300 | Poor |
| 301–400 | Very poor |
| 401–500 | Severe |
Indoor air pollution from solid fuel cooking is a major health risk in rural households (addressed partly by clean cooking fuel schemes).
Water pollution
| Aspect | Details |
|---|---|
| Sources | Untreated domestic sewage (major source), industrial effluents (tanneries, textiles, distilleries), agricultural runoff (fertilisers, pesticides), mining, solid waste leachate, oil spills |
| Indicators | BOD, COD, DO, coliforms, turbidity, TDS, heavy metals, nitrates, phosphates |
| Effects | Waterborne diseases (cholera, typhoid, hepatitis), eutrophication (algal blooms from nutrients → oxygen depletion), fish kills, bioaccumulation and biomagnification of toxins, groundwater contamination (arsenic, fluoride, nitrate) |
| Control | Sewage treatment plants, industrial effluent treatment and zero liquid discharge, controlled fertiliser use, riverfront management, faecal sludge management |
Soil (land) pollution
- Sources: excessive chemical fertilisers and pesticides, industrial waste dumping, landfills and leachate, mining, e-waste, oil spills, plastic.
- Effects: loss of fertility, entry of toxins into food chains, groundwater contamination.
- Control: integrated nutrient and pest management, organic farming, scientific landfills, remediation (bioremediation, phytoremediation).
Noise pollution
- Sources: traffic, aircraft, construction machinery (pile drivers, breakers), industries, loudspeakers, firecrackers.
- Effects: hearing loss, stress, sleep disturbance, hypertension, reduced productivity.
- Control: source control (silencers, quieter equipment, maintenance), noise barriers, zoning, time restrictions, ear protection. Ambient noise standards exist for industrial, commercial, residential and silence zones (day and night limits) under noise pollution rules.
Thermal pollution
- Discharge of heated water from power plants and industries → reduced dissolved oxygen, harm to aquatic life.
- Control: cooling towers, cooling ponds, spray ponds.
Radioactive pollution
- Sources: nuclear accidents, radioactive waste, mining of radioactive minerals, medical/industrial sources.
- Effects: genetic damage, cancers; control through strict regulation (AERB), safe storage and disposal.
Plastic pollution
- Non-biodegradable, persists for centuries; microplastics in water and food chains; clogging of drains (urban flooding); harm to wildlife.
- Measures: reduce, reuse, recycle; ban on identified single-use plastic items in India from 1 July 2022; extended producer responsibility (EPR) for plastic packaging; use of waste plastic in bituminous road construction.
E-waste
- Discarded electronics contain lead, mercury, cadmium, brominated flame retardants and valuable metals.
- Informal recycling (open burning, acid baths) causes serious harm.
- E-waste management rules with EPR obligations for producers; formal collection and recycling (see E-Waste).
Environmental degradation
| Issue | Causes | Consequences |
|---|---|---|
| Deforestation | Agriculture expansion, mining, infrastructure, logging, fires | Loss of biodiversity, soil erosion, altered rainfall, carbon emissions, floods |
| Land degradation and desertification | Overgrazing, deforestation, unsustainable irrigation (waterlogging and salinity), mining, climate variability | Loss of productivity, food insecurity, migration |
| Soil erosion | Water and wind action on exposed soil, steep slope cultivation, construction activity | Loss of topsoil, siltation of reservoirs and rivers |
| Biodiversity loss | Habitat destruction and fragmentation, invasive species, pollution, overexploitation, climate change | Ecosystem instability, loss of genetic resources |
| Wetland degradation | Encroachment, drainage, pollution | Loss of flood buffering, groundwater recharge and habitat |
| Coastal and marine degradation | Mangrove destruction, sand mining, pollution, coral bleaching | Increased coastal erosion and storm damage |
| Groundwater depletion | Over-extraction for irrigation and urban use | Falling water tables, land subsidence, drying wells, saline intrusion |
| Urbanisation impacts | Unplanned growth, impervious surfaces | Urban heat island, urban flooding, waste and sewage burden, air pollution |
| Illegal sand mining | Construction demand | Riverbed lowering, bridge foundation undermining, ecological damage |