Ch 13Environmental Issues — Class 12 Zoology, concept-first.

A clean environment is essential for a peaceful, healthy life, yet through sheer negligence our surroundings are getting dirtier by the day.

Pollution is any undesirable change in the physical, chemical, or biological make-up of the environment, and it can arise from natural causes as well as from human activities.

In terms of how an ecosystem processes them, pollutants fall into two basic groups: degradable and non-degradable.

Earth is surrounded by a gaseous envelope called the atmosphere, which acts as a thermal insulator: it regulates the planet's temperature by selectively absorbing incoming ultraviolet solar radiation.…

Air pollution sources are grouped into four broad categories. Transport sources include cars, buses, airplanes, trucks, and trains -- mobile emitters that release pollutants as they move.

Air pollution affects virtually all organisms because every organism depends on the atmosphere for respiration.

Several specific, named phenomena result from air pollution. Smog is a type of air pollution caused by tiny suspended particles; the word blends 'smoke' and 'fog'.

A range of measures help remove air pollutants, reduce their concentration, or prevent their release altogether.

India's primary legal instrument against air pollution is the Air (Prevention and Control of Pollution) Act, enacted in 1981 and amended in 1987, which provides for the prevention, control, and abatem…

Water is essential both for life directly and for the health of the wider environment. As a valuable natural resource it spans marine, estuarine, freshwater (rivers and lakes), and groundwater environ…

Water quality is not a single number but a composite assessment across several dimensions. Physical characteristics cover properties like temperature, turbidity (cloudiness), and colour.

Water pollution is defined as occurring when there is a change in the chemical, physical, or biological quality of water that has a harmful effect on the living organisms that consume it or live in it…

Although water bodies can occasionally be polluted by natural causes, water pollution is overwhelmingly the result of human activity, and it is usefully classified by how it reaches the water.

Water pollution can severely affect or outright destroy ecosystems, especially aquatic ones. Two distinct ecosystem-level effects are described.

Water pollution can be directly lethal to aquatic organisms and to any other organism that depends on the affected water body. Three specific harms are described.

India treats the right to clean water as a fundamental right under the Constitution. The primary statute is the Water (Prevention and Control of Pollution) Act, 1974, whose Sections 17 to 40 prohibit…

Noise is defined as sound that is unwanted, undesirable, or capable of disrupting one's quality of life; when there is a lot of such 'noise' present in the environment, the condition is termed noise p…

Common sources of noise pollution include vehicle engines, air horns, audio-video systems, trains, low-flying aircraft, factory machines, sirens, motors, drillers and crushers, compressor machines, fi…

According to the United States Environmental Protection Agency (USEPA), there are direct links between noise exposure and health outcomes: heart disease, high blood pressure, stress-related illness, s…

Several practical measures reduce noise pollution. Planting trees in and around noise sources is effective because plants absorb sound and lower ambient noise levels.

Legal protection against noise pollution in India draws on Article 48-A and Article 51-A of the Constitution of India, the Noise Pollution (Regulation and Control) Rules, 2000, and the Tamil Nadu Stat…

Chemicals used in agriculture for the growth of plants and for pest control are called agrochemicals or agrichemicals.

All ecosystems are built from food chains, in which producers and consumers occupy successive trophic levels connected by the flow of energy through eating and being eaten.

When run-off from land carrying nutrients reaches water bodies such as lakes, it results in dense growth of plant life -- a phenomenon called eutrophication.

Wastewater or sewage originates from three sources: domestic wastewater from homes, industrial wastes, and agricultural wastes containing animal waste.

Organic farming is a method of farming that primarily aims to cultivate land and raise crops in a way that keeps the soil alive and in good health.

Every day, tonnes of solid waste are disposed of at landfill sites, generated from homes, offices, industries, and a range of agricultural activities.

Solid waste management practice rests on five core techniques. Source segregation separates waste by type (organic, recyclable, hazardous, and so on) at the point of generation, which is the foundatio…

Radioactive wastes are generated during various operations of nuclear power plants, and can exist as gas, liquid, or solid, with radioactivity levels that vary widely; depending on the level and natur…

Any waste that contains infectious material and is generated by hospitals, laboratories, medical research centres, pharmaceutical companies, or veterinary clinics is classified as medical waste.

Electronic waste, or e-waste, describes discarded electrical and electronic devices, along with any refuse created by discarded electronic devices, their components, and the substances involved in the…

Plastics are low-molecular-weight organic polymers that are non-degradable in the natural environment.

Natural environment and climate are inherently dynamic and change over the course of time; but human population growth, industrialisation, and the associated anthropogenic activities have made these c…

Beyond the general mechanisms of pollution and global environmental change already covered, some ecosystems experience particularly acute or distinctive impacts because of their specific ecology and t…

The marine ecosystem is the source of fish, seaweed, and other marine products that support both livelihoods and food supply for large coastal populations.

At roughly 15 to 30 kilometres above ground level, Earth's atmosphere carries a thin layer of ozone that absorbs ultraviolet sunlight; this layer sits within the atmospheric zone called the stratosphe…

Deforestation is the destruction of forests carried out in order to clear land and make it available for other uses.

People's participation is described as vital to forest conservation, especially the participation of those living in or close to the forest itself; this pattern of local, community-driven forest stewa…

An average Indian individual generates about 150 litres of wastewater daily, and a large share of this comes specifically from toilets.