Samacheer Kalvi 10th Science Chapter 20 Short Answer Questions — Environmental Management with Answers

Environmental management involves the responsible use and conservation of natural resources and the management of pollution to maintain ecological balance and sustain human well-being.

Major types of pollution:

Global warming is the gradual increase in the average temperature of Earth's atmosphere and oceans due to enhanced greenhouse effect.

Causes:

• Burning of fossil fuels (coal, oil, natural gas) releases CO₂
• Deforestation — fewer trees to absorb CO₂
• Agriculture — livestock produce CH₄ (methane); rice paddies release CH₄
• Industrial processes — release CO₂, N₂O, and other greenhouse gases
• CFCs from refrigerants and aerosols

Effects:

• Melting of polar ice caps and glaciers → rise in sea level → flooding of coastal areas
• Climate change — more frequent and intense storms, droughts, floods
• Coral bleaching — warmer oceans kill coral reefs
• Displacement of species — habitats shift; many species face extinction
• Agricultural disruption — changing rainfall patterns, crop failures
• Health impacts — spread of vector-borne diseases to new areas

Control measures:

• Switch to renewable energy (solar, wind)
• Increase energy efficiency
• Reduce deforestation; plant trees
• International agreements: Kyoto Protocol, Paris Agreement

The ozone layer is a region of the stratosphere (15–35 km altitude) containing high concentration of ozone (O₃). It absorbs harmful ultraviolet (UV-B and UV-C) radiation from the sun.

Causes of depletion:

• Chlorofluorocarbons (CFCs) — used in refrigerators, air conditioners, aerosol sprays
• In the stratosphere, UV radiation breaks CFCs → releases chlorine (Cl) atoms
• Cl acts as a catalyst: Cl + O₃ → ClO + O₂; ClO + O → Cl + O₂
• One Cl atom can destroy 100,000 ozone molecules

Effects of ozone depletion:

• Increased UV-B radiation reaching Earth's surface
• Skin cancer and cataracts in humans
• Damage to immune system
• Harm to phytoplankton (base of marine food chain)
• Reduced crop yields

Biodiversity is the variety of all living organisms on Earth at genetic, species, and ecosystem levels. India is one of the 17 megadiverse countries in the world.

Threats to biodiversity:

• Habitat destruction (deforestation, urbanisation)
• Hunting and poaching
• Pollution
• Invasive species
• Climate change

Methods of Conservation:

A. In-situ conservation (in natural habitat):

• National parks — strictly protected; no human activity permitted (Jim Corbett, Mudumalai)
• Wildlife sanctuaries — protection for specific species; limited human activity permitted
• Biosphere reserves — large areas including core (fully protected), buffer, and transition zones
• Sacred groves — forest patches protected by tradition/religion

B. Ex-situ conservation (outside natural habitat):

• Zoos — captive breeding programmes for endangered animals
• Botanical gardens — preserve plant species
• Seed banks — store seeds of crop varieties and wild plants at low temperature
• Gene banks — store genetic material (eggs, sperm, embryos) of endangered species
• Tissue culture — conserve endangered plant species in laboratories

Biomagnification (biological magnification) is the progressive increase in concentration of a non-biodegradable pollutant at each successive trophic level in a food chain.

Why it happens: Non-biodegradable chemicals like DDT, mercury, and PCBs cannot be broken down or excreted by organisms. They accumulate in fatty tissues and remain in the body throughout the organism's lifetime.

Example — DDT in an aquatic food chain:

Effects:

• Top predators (including humans who eat fish) receive the highest concentrations
• DDT caused eggshell thinning in birds — population collapse of eagles and pelicans
• Mercury causes Minamata disease in humans

Lesson: Even small amounts of pollutants in the environment can accumulate to toxic levels in apex predators.

The 3Rs are a hierarchy of waste management strategies to reduce environmental impact:

• Minimise the amount of waste produced in the first place
• Use less packaging, buy only what is needed
• Examples: carrying a reusable bag, printing double-sided, avoiding single-use plastics

• Use items multiple times before discarding
• Repair products instead of replacing
• Examples: refilling water bottles, using cloth bags, repurposing glass jars

• Convert waste materials into new, useful products
• Requires collection, processing, and manufacturing
• Examples: paper recycling, melting glass, recycling metal, composting organic waste

Additional Rs sometimes added:

• Recover — energy recovery from waste (waste-to-energy)
• Refuse — refuse to buy/use items with excessive packaging

Order matters: Reducing is always better than reusing, which is better than recycling. Recycling still requires energy and resources, so it is the last resort before disposal.