ENVIRONMENT GEOGRAPHY TERMS-2

PRERNA FOR IAS

         Mehnat Aapki, Guidance Humari

         Roz ki Prelims Practice — Experts ke Saath

ENVIRONMENT GEOGRAPHY TERMS-2

1. Carbon Cycle

The Carbon Cycle is the continuous movement of carbon among the atmosphere, oceans, soil, rocks, and living organisms. Plants absorb atmospheric carbon dioxide during photosynthesis and convert it into organic matter. Animals obtain carbon by consuming plants or other animals. Carbon returns to the atmosphere through respiration, decomposition, volcanic eruptions, and the burning of fossil fuels. Oceans also absorb and release carbon dioxide, acting as major carbon reservoirs. Human activities such as deforestation and industrial emissions have increased atmospheric carbon dioxide, contributing to climate change. Maintaining a balanced carbon cycle is essential for climate regulation and sustaining life.

2. Nitrogen Cycle

The Nitrogen Cycle is the natural circulation of nitrogen between the atmosphere, soil, plants, animals, and microorganisms. Although nitrogen makes up about 78% of Earth's atmosphere, most organisms cannot use it directly. Nitrogen-fixing bacteria convert atmospheric nitrogen into ammonia, which is further transformed into nitrates through nitrification. Plants absorb nitrates to produce proteins, while animals obtain nitrogen by eating plants or other animals. Decomposers return nitrogen to the soil, and denitrifying bacteria convert nitrates back into atmospheric nitrogen. The nitrogen cycle maintains soil fertility, supports agriculture, and ensures continuous nutrient recycling in ecosystems.

3. Hydrological Cycle

The Hydrological Cycle, also known as the Water Cycle, is the continuous movement of water between the Earth's surface and the atmosphere. Water evaporates from oceans, lakes, and rivers due to solar energy. Plants release water vapour through transpiration. Water vapour condenses into clouds and returns to Earth as precipitation such as rain or snow. Some water infiltrates into the ground, while the rest flows as runoff into rivers and oceans. This cycle regulates Earth's climate, replenishes freshwater resources, supports ecosystems, and maintains the availability of water for agriculture, industry, and human consumption.

4. Greenhouse Effect

The Greenhouse Effect is the natural process by which certain gases in the atmosphere trap heat and keep the Earth warm enough to support life. Greenhouse gases such as carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), and water vapour absorb outgoing infrared radiation and re-radiate it toward the Earth's surface. Without the natural greenhouse effect, Earth's average temperature would be about –18°C, making life impossible. However, excessive greenhouse gas emissions caused by human activities enhance this effect, leading to global warming and climate change. Maintaining a balanced greenhouse effect is essential for environmental stability.

5. Global Warming

Global warming refers to the long-term increase in Earth's average surface temperature due to the enhanced greenhouse effect caused mainly by human activities. Burning fossil fuels, deforestation, industrialization, and agriculture release large amounts of greenhouse gases into the atmosphere. Rising temperatures lead to melting glaciers, sea-level rise, changing rainfall patterns, stronger heatwaves, and loss of biodiversity. Global warming also affects agriculture, human health, and freshwater availability. Reducing greenhouse gas emissions, increasing renewable energy use, protecting forests, and promoting sustainable lifestyles are important strategies for limiting global warming and reducing its environmental impacts.

6. Climate Change

Climate change refers to long-term changes in Earth's climate, including temperature, rainfall, wind patterns, and extreme weather events. It is caused by both natural processes and human activities, although recent climate change is largely driven by increased greenhouse gas emissions. Climate change leads to rising sea levels, melting ice caps, frequent droughts, floods, cyclones, and biodiversity loss. It threatens food security, water resources, public health, and ecosystems worldwide. International agreements such as the Paris Agreement aim to reduce greenhouse gas emissions. Climate adaptation and mitigation are essential for reducing future environmental and economic risks.

7. Ozone Layer

The ozone layer is a region of the stratosphere containing a high concentration of ozone (O₃) molecules. It forms approximately 15–35 kilometres above the Earth's surface and absorbs most of the Sun's harmful ultraviolet (UV-B and UV-C) radiation. By filtering UV radiation, the ozone layer protects humans, animals, and plants from skin cancer, cataracts, DNA damage, and reduced crop productivity. Chemicals such as chlorofluorocarbons (CFCs) previously caused severe ozone depletion. International cooperation through the Montreal Protocol (1987) has significantly reduced ozone-depleting substances, allowing gradual recovery of the ozone layer.

8. Ozone Depletion

Ozone depletion is the reduction in the concentration of ozone in the stratosphere due to chemicals such as chlorofluorocarbons (CFCs), halons, and other ozone-depleting substances. These chemicals release chlorine and bromine atoms that destroy ozone molecules. Ozone depletion allows more harmful ultraviolet radiation to reach the Earth's surface, increasing the risk of skin cancer, cataracts, weakened immune systems, and damage to crops and marine ecosystems. The Antarctic Ozone Hole is the best-known example of ozone depletion. Global action under the Montreal Protocol has successfully reduced ozone-depleting substances and promoted ozone layer recovery.

9. Acid Rain

Acid rain is rainfall with unusually high acidity caused by sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) released from industries, thermal power plants, and vehicles. These gases react with atmospheric moisture to form sulfuric and nitric acids, which fall as rain, snow, fog, or dry deposition. Acid rain damages forests, lakes, rivers, crops, buildings, and historical monuments such as the Taj Mahal. It also affects soil fertility and aquatic ecosystems. Reducing industrial emissions, using cleaner fuels, and installing pollution-control technologies help prevent acid rain and protect environmental health.

10. Air Pollution

Air pollution is the contamination of the atmosphere by harmful gases, smoke, dust, chemicals, and particulate matter. Major sources include industries, motor vehicles, burning fossil fuels, agricultural activities, and forest fires. Air pollutants such as PM2.5, PM10, sulfur dioxide, nitrogen oxides, ozone, and carbon monoxide can cause respiratory diseases, cardiovascular disorders, and environmental damage. Air pollution also contributes to acid rain, global warming, and reduced visibility. Governments promote emission standards, renewable energy, public transport, and cleaner technologies to reduce pollution. Clean air is essential for human health, biodiversity, and sustainable development.

11. Water Pollution

Water pollution occurs when harmful substances contaminate rivers, lakes, oceans, groundwater, and other water bodies. Major pollutants include industrial effluents, sewage, agricultural fertilizers, pesticides, plastics, heavy metals, and oil spills. Water pollution reduces water quality, harms aquatic organisms, spreads diseases, and disrupts ecosystems. Polluted water also affects drinking water supplies, agriculture, fisheries, and public health. Wastewater treatment, pollution control laws, proper waste disposal, and sustainable agricultural practices help reduce water pollution. Protecting freshwater resources is essential for environmental sustainability, biodiversity conservation, and ensuring safe water for present and future generations.

12. Soil Pollution

Soil pollution refers to the contamination of soil by harmful chemicals, industrial wastes, pesticides, fertilizers, heavy metals, plastics, and other pollutants. Polluted soil loses fertility, reduces agricultural productivity, and affects plant growth. Toxic substances may enter the food chain, posing risks to human and animal health. Soil pollution also damages soil microorganisms that are essential for nutrient cycling. Sustainable farming practices, organic agriculture, proper waste management, and reduced chemical use help restore soil quality. Healthy soil is vital for food production, biodiversity, carbon storage, and maintaining ecological balance within terrestrial ecosystems.

13. Noise Pollution

Noise pollution is the presence of excessive or unwanted sound that causes discomfort, stress, or health problems. Common sources include road traffic, railways, aircraft, industries, construction activities, loudspeakers, and urban development. Continuous exposure to high noise levels can cause hearing loss, sleep disturbances, hypertension, anxiety, reduced concentration, and cardiovascular diseases. Noise pollution also affects wildlife by interfering with communication, migration, and reproduction. Governments regulate permissible noise levels through environmental laws. Soundproofing, green belts, quieter technologies, and public awareness are important measures to reduce noise pollution and improve quality of life.

14. Thermal Pollution

Thermal pollution is the undesirable increase in the temperature of natural water bodies caused mainly by industrial cooling water discharged from power plants and factories. Warm water contains less dissolved oxygen, reducing the survival of fish and other aquatic organisms. Higher temperatures may alter aquatic food chains, encourage algal growth, and disturb ecosystem balance. Thermal pollution also affects breeding and migration of aquatic species. Cooling towers, cooling ponds, heat exchangers, and recycling of industrial water are effective methods of reducing thermal pollution. Maintaining natural water temperatures is essential for healthy aquatic ecosystems and biodiversity conservation.

15. Radioactive Pollution

Radioactive pollution is the contamination of the environment by radioactive substances released from nuclear power plants, mining, nuclear weapons testing, medical waste, or industrial accidents. Radioactive materials emit harmful radiation that can damage living cells, cause cancer, genetic mutations, birth defects, and long-term environmental contamination. Radioactive pollution may persist for decades because some radioactive isotopes have long half-lives. Strict safety measures, secure disposal of radioactive waste, radiation monitoring, and international regulations help minimize radioactive pollution. Preventing radioactive contamination is essential for protecting human health, ecosystems, and future generations.

16. Eutrophication

Eutrophication is the excessive enrichment of lakes, ponds, reservoirs, and rivers with nutrients such as nitrogen and phosphorus, mainly from agricultural runoff, sewage, and industrial waste. These nutrients stimulate rapid growth of algae and aquatic plants, forming algal blooms. When algae die, decomposers consume large amounts of dissolved oxygen, creating oxygen-deficient conditions known as hypoxia. Fish and other aquatic organisms may die due to lack of oxygen. Controlling fertilizer use, treating sewage, and preventing nutrient-rich runoff help reduce eutrophication and maintain healthy freshwater ecosystems.

17. Biomagnification

Biomagnification is the gradual increase in the concentration of toxic substances at successive trophic levels in a food chain. Pollutants such as DDT, mercury, and PCBs cannot be easily broken down, so they accumulate in organisms. As predators consume contaminated prey, the concentration of toxins becomes progressively higher at each trophic level. Top predators, including humans, often receive the highest concentrations of harmful chemicals. Biomagnification can cause reproductive failure, nervous system disorders, and population decline in wildlife. Controlling persistent pollutants is essential for protecting ecosystems and human health.

18. Bioaccumulation

Bioaccumulation is the gradual build-up of harmful substances such as pesticides, heavy metals, or industrial chemicals within the tissues of a single organism over time. Unlike biomagnification, bioaccumulation occurs within an individual organism because the pollutants are absorbed faster than they can be eliminated. Long-lived organisms usually accumulate higher concentrations of toxins. Bioaccumulation can impair growth, reproduction, immunity, and survival. Humans may also accumulate harmful chemicals through contaminated food and water. Reducing pollution, monitoring toxic substances, and regulating hazardous chemicals are important measures for preventing bioaccumulation and protecting environmental health.

19. Deforestation

Deforestation is the large-scale clearing and removal of forests for agriculture, urbanization, mining, industries, infrastructure development, and logging. It leads to habitat destruction, biodiversity loss, soil erosion, disruption of the water cycle, and increased carbon dioxide levels in the atmosphere. Deforestation contributes significantly to climate change by reducing the Earth's capacity to absorb carbon. It also affects indigenous communities and wildlife dependent on forests. Sustainable forestry, afforestation, reforestation, community participation, and strict conservation policies are essential for reducing deforestation and preserving ecological balance and natural resources.

20. Afforestation

Afforestation is the establishment of forests on land that has not been forested in recent history. It differs from reforestation because it creates forests in previously non-forest areas. Afforestation improves biodiversity, prevents soil erosion, conserves water, enhances carbon sequestration, and helps combat climate change. It also provides timber, fuelwood, employment, and wildlife habitat. Governments and environmental organizations promote afforestation through social forestry, urban forestry, and large-scale tree plantation programmes. Successful afforestation requires selecting suitable native species, proper land management, and long-term maintenance. It is an important strategy for achieving sustainable environmental development.