Environmental Studies Unit 5/8

Biodiversity

The variety and variability of all living organisms (plants, animals, microbes) and the ecological complexes they inhabit, including diversity within and between species and ecosystems.

Species Diversity

Variation in the number and kinds of species present in a particular region or ecosystem.

Genetic Diversity

The range of genetic characteristics (genes, alleles) found within individuals of a species and between populations of the same species.

Ecosystem Diversity

The variety of habitats, biological communities and ecological processes in the biosphere (e.g., forests, grasslands, deserts, coral reefs).

Biogeographic Zone

A geographic area classified on the basis of characteristic species, habitats and physical features (India has 10 zones).

Biodiversity Hotspot

A biogeographic area with exceptionally high levels of endemic plant species (≥1,600) that is also under severe threat of habitat loss.

Mega-biodiversity Nation

A country containing an extraordinary percentage of Earth’s species; India is one of 12 such nations.

Endangered Species

Species whose populations have declined so drastically that they face a high risk of extinction in the near future.

Endemic Species

Species that occur naturally only in a specific geographic area and nowhere else in the world.

In-situ Conservation

Protection of species in their natural habitats (e.g., national parks, wildlife sanctuaries, biosphere reserves).

Ex-situ Conservation

Conservation of components of biodiversity outside their natural habitats (e.g., zoos, gene banks, botanical gardens, seed banks).

Habitat Loss

Destruction or degradation of natural environments, leading to decline in biodiversity (often caused by deforestation, urbanisation, agriculture).

Poaching

Illegal hunting or capturing of wild animals for trade, meat, trophies or other products, contributing to species decline.

Man-wildlife Conflict

Negative interactions between humans and wild animals resulting in crop damage, livestock loss, property damage or injury/death to either party.

Ecosystem Services

Benefits humans obtain from ecosystems, such as oxygen production, nutrient cycling, climate regulation and water purification.

Consumptive Use Value

Direct use of biodiversity for subsistence needs (e.g., fuelwood, food, medicinal plants harvested for personal use).

Productive Use Value

Commercial value derived from harvesting and selling biodiversity-based products (e.g., timber, pharmaceuticals, ornamental plants).

Ethical and Moral Value

The principle that all forms of life have an inherent right to exist and should be protected from undue harm.

Aesthetic Value

The enjoyment and inspiration humans derive from the beauty and uniqueness of biodiversity, often driving ecotourism.

Environmental Value

The role biodiversity plays in maintaining ecological processes such as soil formation, water regulation and climate stability.

Social Value

Cultural, religious and recreational importance attached to biodiversity by human societies (e.g., sacred groves, festival plants).

Trans-Himalayan Region

Cold desert biogeographic zone of Ladakh, parts of J&K and Himachal; habitat for Snow Leopard and Black-necked Crane.

Himalayan Zone

Mountainous biogeographic zone rich in alpine and mixed forests; home to Himalayan Tahr, Musk Deer, Ibex, Hangul.

Indian Desert Zone

Arid biogeographic zone covering Thar and Kutch deserts; supports species like Desert Cat and Indian Wolf.

Semi-arid Region

Transition zone between desert and Western Ghats; characteristic fauna include Asiatic Lion, Caracal, Jackal.

Western Ghats

Mountain range along India’s west coast; a biodiversity hotspot with endemic species such as Lion-tailed Macaque and Nilgiri Tahr.

Deccan Plateau

Largest Indian biogeographic region (42 % area) with deciduous and thorn forests; species include Chital, Nilgai, Gaur.

Gangetic Plain

Fertile alluvial zone along River Ganga; characteristic fauna include Indian Rhino, Asian Elephant and Hog Deer.

North-East Region

Transition zone linking Indian, Indo-Malayan and Indo-Chinese realms; gateway for many unique flora and fauna.

Coastal Region

Biogeographic zone with beaches, mangroves and coral reefs along India’s 5,425 km coastline; high marine biodiversity.

Andaman & Nicobar Islands

Indian archipelago with tropical moist evergreen forests and high endemism (e.g., Narcondam Hornbill).

Biosphere Reserve

Large, internationally recognised area aimed at conserving ecosystems while promoting sustainable use by local communities.

National Park

Protected area managed mainly for ecosystem protection and recreation; human activities are highly restricted.

Gene Sanctuary

Protected area specifically set aside for the in-situ conservation of genetic diversity of crop wild relatives (e.g., citrus in Garo Hills).

Abiotic

Non-living physical and chemical components of an ecosystem (e.g., temperature, water, minerals).

Biotic

Living components of an ecosystem, including plants, animals and microorganisms.

Depletion

Gradual reduction in quantity or abundance of natural resources such as forests, water or species.

Mass Extinction

Event in which a large number of species become permanently extinct in a relatively short geological time span.

Captive Breeding

Ex-situ conservation technique involving breeding threatened species in controlled environments to increase population size.

Cryopreservation

Long-term ex-situ conservation method where biological material (seeds, sperm, embryos) is stored at ultra-low temperatures.

Water Pollution

Presence of harmful physical, chemical or biological substances in freshwater or other water bodies.

Point-Source Pollution

Contamination that originates from a single, identifiable discharge such as a pipe, drain, well or factory outlet.

Non-Point Source Pollution

Diffuse pollution carried by rainfall or snow-melt runoff across wide areas without a single identifiable origin.

Sediment Pollution

Run-off of soil particles that increases turbidity and blocks sunlight, harming aquatic plants and animals.

Nutrients (Nitrogen & Phosphorus)

Inorganic compounds that, in excess, overstimulate plant and algal growth leading to eutrophication.

Pathogens

Disease-causing microorganisms (bacteria, viruses, protozoa) that contaminate water supplies.

Toxic Contaminants

Persistent chemicals such as heavy metals, PAHs or PCBs that do not readily degrade and can poison living organisms.

Eutrophication

Oxygen depletion that follows excessive algal growth and decomposition, producing aquatic ‘dead zones’.

Blue Baby Syndrome

Infant methemoglobinemia caused by high nitrate levels in drinking water, reducing oxygen transport in blood.

Ocean Acidification

Ongoing decrease in ocean pH from CO₂ absorption, impairing shell-forming organisms like corals and shellfish.

Dissolved Oxygen (DO)

Amount of oxygen gas dissolved in water; essential for respiration of aquatic organisms.

Biochemical Oxygen Demand (BOD)

Quantity of oxygen required by microbes to decompose organic matter in water over a set time.

Chemical Oxygen Demand (COD)

Measure of oxygen equivalent consumed in chemical oxidation of organic compounds within a water sample.

Physical Contaminants

Pollutants that change water’s physical qualities such as colour, temperature, or turbidity.

Chemical Contaminants

Inorganic or organic chemical substances (salts, metals, pesticides) present in water.

Biological Contaminants

Living organisms—including bacteria, algae, protozoa—that pollute water and may cause disease.

Radiological Contaminants

Unstable isotopes (e.g., uranium, radon) that emit ionising radiation when present in water.

Organic Contaminants

Carbon-based pollutants such as petroleum hydrocarbons, detergents, pesticides and solvents.

Inorganic Contaminants

Non-carbon pollutants like ammonia, nitrates, phosphates and heavy metals from industrial or natural sources.

Macroscopic Contaminants

Large visible debris—trash, plastics, shipwrecks—that can harm aquatic life and aesthetics.

Thermal Pollution

Sudden rise or fall in water temperature, typically from industrial cooling water discharges, reducing oxygen solubility.

Microbial Contaminants

Indicators such as faecal coliform bacteria that signal sewage contamination of water.

pH

Measure of hydrogen-ion concentration; values below 7 indicate acidity, above 7 alkalinity.

Total Dissolved Solids (TDS)

Concentration of non-volatile dissolved substances in water, expressed in mg/L.

Turbidity

Cloudiness of water caused by suspended particles; measured in NTU or by a Secchi disc.

Electrical Conductivity (EC)

Ability of water to conduct electricity due to dissolved ions; rises with salinity.

Hardness

Amount of calcium and magnesium ions in water that affects soap lathering and scaling.

Salinity

Total concentration of dissolved salts—especially sodium chloride—in water.

Alkalinity

Water’s capacity to neutralise acids, mainly due to bicarbonates and carbonates.

Primary Wastewater Treatment

Initial settling process that removes large solids and floating matter from wastewater.

Secondary Wastewater Treatment

Biological stage (biofiltration, aeration, oxidation ponds) that degrades dissolved and suspended organic matter.

Tertiary Wastewater Treatment

Advanced processes that remove pathogens, nutrients, colour and dissolved chemicals, producing high-quality effluent.

Biofiltration

Passing wastewater through media where microbial films degrade organic pollutants.

Aeration

Introducing air or oxygen into water to raise dissolved oxygen and oxidise contaminants.

Oxidation Pond

Shallow lagoon using sunlight, algae and bacteria to biologically treat wastewater.

Effluent Polishing

Final filtration step using granular media or micro-strainers to remove residual suspended solids.

Land Treatment

Application of wastewater to soil where physical, chemical and biological processes purify it.

Sewage Treatment Plant (STP)

Facility that treats domestic wastewater through primary, secondary and tertiary processes.

Industrial Wastewater Treatment

Specialised processes that remove specific contaminants from industrial effluents before discharge or reuse.

Agricultural Wastewater Treatment

Practices and facilities controlling runoff and animal waste from farms to reduce water pollution.

Leachate Treatment Plant

System designed to treat polluted liquid draining from landfills, using biological, mechanical or chemical methods.

Constructed Wetlands

Engineered marshes that use plants, soil and microbes to cleanse municipal or industrial wastewater.

Minamata Disease

Neurological disorder from severe mercury poisoning first recorded in Minamata, Japan.

Heavy Metals

Dense metallic elements such as mercury, lead and cadmium that bioaccumulate and are toxic even at low levels.

PAHs (Polycyclic Aromatic Hydrocarbons)

Persistent organic pollutants formed by incomplete combustion; harmful to aquatic life and humans.

PCBs (Polychlorinated Biphenyls)

Synthetic chlorinated compounds formerly used in industry; highly persistent and toxic environmental pollutants.

Secchi Disc

White opaque disc used to measure water transparency and estimate turbidity depth.

Water Harvesting

Collection and storage of rainwater for later use, reducing demand on freshwater sources.

Bioremediation

Use of microorganisms or plants to degrade or remove pollutants from contaminated water or soil.

“Jal Nahi, To Kal Nahi”

Hindi slogan meaning “No water, no future,” stressing the necessity of water conservation.

Air Pollution

Presence of harmful gases, particulates, or biological molecules in the atmosphere that endanger human health and the environment.

Particulate Matter (PM)

Mixture of tiny solid particles and liquid droplets (dust, soot, smoke) suspended in air; classified by size such as PM10 and PM2.5.

PM2.5

Fine particulate matter with aerodynamic diameter ≤ 2.5 µm; penetrates deep into lungs and blood stream.

PM10

Coarse particulate matter with aerodynamic diameter ≤ 10 µm; can irritate eyes, nose and throat.

Primary Pollutant

Contaminant emitted directly from a source, e.g., CO, SO₂, NOx, particulate matter.

Secondary Pollutant

Pollutant formed in the atmosphere through chemical reactions between primary pollutants, e.g., ozone, sulphur trioxide.

Nitrogen Dioxide (NO₂)

Reddish-brown toxic gas produced mainly by vehicle exhausts, power plants and heating; causes respiratory irritation.

Sulphur Dioxide (SO₂)

Colourless, suffocating gas released from burning coal and oil; precursor of acid rain.

Carbon Monoxide (CO)

Colourless, odourless gas from incomplete combustion of fuels; binds with haemoglobin and reduces oxygen delivery.

Ground-level Ozone

Secondary pollutant formed by sunlight-driven reactions of NOx and VOCs; harmful to lungs and vegetation.