Environmental Concerns & Pollution

The One Thing

Human activities can disturb ecosystem balance and damage air, water, and soil when harmful substances or forms of energy enter the environment in damaging amounts. Pollution is reduced most effectively through prevention at the source, responsible resource use, treatment, recovery, reuse, recycling, and safe disposal.

Reactions, Processes and Experiments

Key Terms

• Environment: The surroundings of living organisms, including living factors such as plants and animals and non-living factors such as air, water, soil, light, and temperature.
• Environmental pollution: An undesirable change in the physical, chemical, or biological characteristics of the environment caused by harmful substances or activities.
• Pollutant: Any substance, organism, or form of energy that causes pollution or harms living organisms and their surroundings.
• Biodegradable waste: Waste that can be broken down into simpler substances by microorganisms, such as bacteria and fungi.
• Non-biodegradable waste: Waste that cannot be easily broken down by natural decomposers and may remain in the environment for a very long time.
• Air pollution: The presence of harmful gases, smoke, dust, or fine particles in the atmosphere in concentrations that affect health or the environment.
• Water pollution: The contamination of water by sewage, chemicals, fertilizers, plastics, disease-causing organisms, or other harmful materials.
• Soil pollution: The accumulation of harmful chemicals, solid waste, pesticides, or other pollutants in soil, reducing its quality and fertility.
• Noise pollution: Unwanted or excessive sound that causes discomfort, stress, hearing problems, or disturbance to animals and humans.
• Radioactive pollution: A major type of pollution involving harmful radioactive substances or radiation.
• Greenhouse effect: The warming of Earth caused when gases such as carbon dioxide, methane, and water vapour trap heat in the atmosphere.
• Global warming: The long-term rise in Earth's average temperature, mainly due to the increased concentration of greenhouse gases from human activities.
• Greenhouse gases: Atmospheric gases that absorb and re-radiate heat, including carbon dioxide, methane, nitrous oxide, water vapour, and some industrial gases.
• Ozone depletion: The thinning of the stratospheric ozone layer, which reduces protection from harmful ultraviolet radiation.
• Acid rain: Rain or other precipitation made unusually acidic when sulphur dioxide and nitrogen oxides react with atmospheric moisture to form acids.
• Smog: A polluted mixture of smoke, gases, and fine particles that reduces visibility and may cause breathing problems.
• Eutrophication: Excessive growth of algae in water due to nutrient enrichment, followed by oxygen depletion and harm to aquatic life.
• Biochemical oxygen demand: The amount of dissolved oxygen required by microorganisms to decompose organic matter in water; high demand generally indicates greater organic pollution.
• Biomagnification: The increase in concentration of persistent toxic substances at successive levels of a food chain.
• Waste management: The collection, separation, treatment, reuse, recycling, and safe disposal of waste.
• Composting: The controlled decomposition of biodegradable organic waste to produce nutrient-rich compost.
• Recycling: Processing used materials into new products to conserve resources and reduce waste.
• Sustainable development: Development that meets present needs without reducing the ability of future generations to meet their needs.

Easily Confused

• Biodegradable waste and non-biodegradable waste: Biodegradable waste is broken down naturally by microorganisms, whereas non-biodegradable waste persists and may accumulate.
• Greenhouse effect and global warming: The greenhouse effect is the heat-trapping process caused by atmospheric gases, whereas global warming is the long-term rise in Earth’s average temperature.
• Ozone depletion and global warming: Ozone depletion reduces protection from ultraviolet radiation, whereas global warming results mainly from increased heat retention by greenhouse gases.
• Eutrophication and biochemical oxygen demand: Eutrophication is nutrient-driven algal growth followed by oxygen depletion, whereas biochemical oxygen demand measures the oxygen microorganisms require to decompose organic matter.
• Reduce, reuse, and recycle: Reduce means consuming less and preventing waste; reuse means using an item again; recycle means processing used material into a new product.
• Air pollution and smog: Air pollution is the broad contamination of the atmosphere, whereas smog is a polluted mixture of smoke, gases, and fine particles.
• Pollutant and pollution: A pollutant is the harmful substance, organism, or energy, whereas pollution is the undesirable environmental change caused by it.
• Composting and recycling: Composting biologically decomposes organic waste into compost, whereas recycling processes used materials into new products.
• Prevention and treatment: Prevention stops pollutants from being produced or released, whereas treatment deals with waste or pollution after it has been generated.

What Gets Asked

• Questions may require classification of the major types of pollution: air, water, soil, noise, and radioactive pollution. Marks are lost by giving examples or effects that belong to a different type.
• Questions may ask for common air pollutants and their effects. The specific points include carbon monoxide forming carboxyhaemoglobin, sulphur dioxide and nitrogen oxides contributing to acid rain, and particulate matter causing respiratory problems.
• Questions may present a water-pollution scenario involving sewage, fertilisers, or industrial effluents. The required links are disease transmission from untreated sewage, eutrophication from excess nitrates and phosphates, and high biochemical oxygen demand causing oxygen depletion.
• Questions may ask for distinctions between biodegradable and non-biodegradable waste or for suitable management methods. Biodegradable waste is treated by composting or anaerobic digestion, while persistent waste should be reused, recycled, or safely disposed of rather than burned or dumped in water bodies.
• Questions may require the equation or calculation for pollution reduction. The expression must be written as: percentage reduction = ((initial pollution level - final pollution level) / initial pollution level) x 100.
• Questions may assess environmental protection measures, including prevention at the source, waste segregation, the 3Rs, conservation of energy and water, renewable energy, public transport, emission-control devices, afforestation, and individual actions such as avoiding littering, limiting plastic use, saving electricity, and using resources carefully.
• Questions may test environmental legislation and observances in India: the Environment (Protection) Act, 1986; the Water (Prevention and Control of Pollution) Act, 1974; the Air (Prevention and Control of Pollution) Act, 1981; the National Green Tribunal, established in 2010; World Environment Day on 5 June; and Earth Day on 22 April.