WBCHSE HS Environmental Science cheat sheet

Environment = all biotic and abiotic surroundings; environmental science is interdisciplinary, drawing on biology, chemistry, physics, economics and law.

Four spheres: atmosphere (gases), hydrosphere (water), lithosphere (crust and soil), biosphere (living organisms); matter cycles between them.

Ecosystem components: producers (autotrophs), consumers (herbivores, carnivores, omnivores, decomposers) and abiotic factors such as light, temperature and nutrients.

Food chain transfers energy; food web is interlinked chains; trophic level = feeding position counted from the producer as level 1.

10% law: only about 10% of energy passes to the next trophic level, so food chains rarely exceed 4-5 links.

Ecological pyramid of numbers, biomass or energy; energy pyramids are always upright, numbers pyramids may be inverted (e.g., one tree, many insects).

Habitat = place where an organism lives; niche = its functional role including resource use and interactions; two species cannot occupy an identical niche indefinitely (competitive exclusion).

Ecosystem services: provisioning (food, water), regulating (climate, flood control), supporting (nutrient cycling) and cultural (recreation, education).

Renewable resources (solar, wind, biomass, water) regenerate within human timescales; non-renewable (coal, petroleum, minerals) are finite stocks.

Soil erosion is accelerated by deforestation, overgrazing and slope cultivation; contour ploughing, terracing, strip cropping and shelterbelts check it.

Deforestation effects: loss of biodiversity, soil erosion, reduced rainfall, increased CO2, and altered hydrology; afforestation and social forestry counter it.

Water conservation: rainwater harvesting, watershed management, drip and sprinkler irrigation, and recycling of industrial water.

Overexploitation of groundwater lowers the water table and can cause land subsidence and saltwater intrusion along coasts.

Energy conservation: use of public transport, LED lighting, energy-efficient appliances, cogeneration and waste-heat recovery.

Sustainable resource use means consumption rate does not exceed regeneration rate; maximum sustainable yield is the largest harvest that can be taken indefinitely.

Mineral resources are non-renewable; recycling, substitution and improved mining efficiency extend reserve life.

Levels of biodiversity: genetic (within species), species (between species) and ecosystem (variety of habitats and communities).

Hotspots are regions of high species richness and endemism under severe threat; India's include the Himalaya, Western Ghats, Indo-Burma and Sundaland (Nicobar).

IUCN Red List categories: Extinct, Extinct in the Wild, Critically Endangered, Endangered, Vulnerable, Near Threatened, Least Concern, Data Deficient.

In-situ conservation: national parks, sanctuaries, biosphere reserves, sacred groves; ex-situ: zoos, botanical gardens, seed banks, cryopreservation.

In India, a national park is legally protected with no human activity permitted; a sanctuary allows limited regulated activities; a biosphere reserve has core, buffer and transition zones.

Wildlife (Protection) Act 1972 provides schedules for protected species; Project Tiger (1973) and Project Elephant (1992) are flagship conservation programmes.

Causes of biodiversity loss: habitat destruction and fragmentation, overexploitation, invasive alien species, pollution and climate change (the 'evil quartet' plus climate).

Endemic species occur naturally only in one restricted area; keystone species have disproportionately large effects on community structure.

Air pollutants: primary (SO2, NOx, CO, particulates) emitted directly; secondary (ozone, PAN, sulphuric and nitric acid) formed in the atmosphere.

Photochemical smog forms from NOx and volatile organic compounds under sunlight; London-type smog is reducing (smoke + SO2 + fog).

Classical air pollution episodes: London 1952 (smoke and SO2), Donora 1948, Bhopal 1984 (methyl isocyanate gas leak).

Water pollution indicators: BOD (biochemical oxygen demand) and COD measure organic load; high BOD means high organic pollution and low dissolved oxygen.

Eutrophication: nutrient (N, P) enrichment causes algal blooms, oxygen depletion and fish kills; control by nutrient removal and buffer strips.

Noise is measured in decibels (dB); permissible residential limit in India is 55 dB(A) daytime and 45 dB(A) night.

Solid waste management hierarchy: reduce > reuse > recycle > recover (energy) > dispose; sanitary landfill and composting are preferred to open dumping.

Pollution control devices: electrostatic precipitator and bag filter for particulates; catalytic converter for CO and NOx in vehicles; scrubbers for SO2.

pH = -log[H+]; a change of one pH unit means a tenfold change in hydrogen ion concentration; acid rain pH is below 5.6.

Acid rain forms from SO2 and NOx converted to H2SO4 and HNO3; it acidifies lakes and mobilises aluminium, harming fish.

Greenhouse gases ranked by contribution: CO2, CH4, N2O, CFCs, water vapour; global warming potential of CH4 is about 25-28 times CO2 over 100 years.

Ozone depletion is driven by chlorine and bromine from CFCs and halons; the Montreal Protocol (1987) phases out ozone-depleting substances.

Bioaccumulation = build-up within one organism; biomagnification = increase in concentration along the food chain (e.g., DDT, mercury in fish).

Toxicology terms: dose-response relationship, LD50 (dose lethal to 50% of test animals), threshold limit value, chronic vs acute exposure.

Heavy metals (Pb, Hg, Cd, As) are non-biodegradable; lead affects nervous system, mercury causes Minamata disease, cadmium causes Itai-itai disease.

Persistent organic pollutants are lipophilic and resist degradation; they are regulated under the Stockholm Convention.

Population growth: exponential (J-shaped) when resources unlimited; logistic (S-shaped) with carrying capacity K when limited.

Biotic potential is maximum reproductive rate under ideal conditions; environmental resistance limits realised growth.

Species interactions: mutualism (+,+), commensalism (+,0), parasitism (+,−), predation (+,−), competition (−,−), amensalism (−,0).

Ecological succession: primary succession starts on bare substrate (lithosere, hydrosere); secondary succession follows disturbance with soil already present.

Pioneer species are hardy colonisers; climax community is the stable end stage in equilibrium with climate.

Biogeochemical cycles: gaseous (carbon, nitrogen, oxygen) have atmospheric reservoirs; sedimentary (phosphorus, sulphur) have rock and soil reservoirs.

Nitrogen fixation by Rhizobium, Azotobacter and cyanobacteria; nitrification by Nitrosomonas and Nitrobacter; denitrification returns N2 to atmosphere.

Ecological indicators: lichens indicate SO2 air quality; mayfly and stonefly larvae indicate clean, oxygen-rich water.

Electromagnetic spectrum order by increasing wavelength: gamma, X-ray, UV, visible, infrared, microwave, radio; ozone absorbs UV-B and UV-C.

Albedo is the fraction of incident solar radiation reflected; snow and ice have high albedo, oceans and forests low albedo.

Greenhouse effect: shortwave solar radiation passes the atmosphere; longwave infrared emitted by Earth is absorbed and re-radiated by greenhouse gases.

Global warming potential compares heat trapped by a gas with CO2 over a set period; CO2 equivalent (CO2e) sums all gases.

Renewable energy: solar photovoltaic, solar thermal, wind, hydro, biomass, geothermal, tidal and wave; non-renewable: coal, oil, gas, nuclear fuel.

Wind power depends on the cube of wind speed (P ∝ v³); solar panel output depends on irradiance, angle and temperature.

Climate vs weather: weather is short-term atmospheric state; climate is the long-term average and variability (typically 30 years).

Ocean acidification: rising atmospheric CO2 dissolves to form carbonic acid, lowering ocean pH and harming calcifying organisms.

Sustainable development = meeting present needs without compromising the ability of future generations to meet theirs (Brundtland Report, 1987).

Three pillars of sustainability: environmental, social and economic; the Rio Earth Summit (1992) adopted Agenda 21 and the Rio Declaration.

The 17 Sustainable Development Goals (2015) replaced the MDGs; SDG 13 is climate action, SDG 6 clean water, SDG 15 life on land.

Environmental Impact Assessment (EIA) predicts impacts before project approval; in India EIA is governed by the Environment (Protection) Act 1986 notifications.

Key Indian laws: Water Act 1974, Air Act 1981, Environment (Protection) Act 1986 (umbrella law), Wildlife Protection Act 1972, Forest Conservation Act 1980.

Polluter pays principle and precautionary principle were adopted in the Rio Declaration; the public trust doctrine makes the State trustee of natural resources.

Environmental management tools: ISO 14001 environmental management systems, life-cycle assessment, environmental auditing, carbon footprinting.

Central Pollution Control Board (CPCB) sets standards and monitors; State Pollution Control Boards issue consent to establish and operate.

Quadrat method: a square frame of known area; density = number of individuals / area; frequency = (quadrats containing species / total quadrats) × 100.

Line transect and belt transect estimate abundance and distribution along a gradient; point-intercept records species touching a pin.

Simpson's index D = 1 − Σ(n/N)²; higher D indicates greater diversity; Shannon index H' = −Σ p ln p.

Water quality field tests: pH, temperature, dissolved oxygen (Winkler method), turbidity, total dissolved solids, BOD.

Air quality sampling: high-volume sampler for suspended particulate matter; grab sampling for gaseous pollutants; use of indicator lichens.

Soil analysis: pH by pH meter, organic carbon by Walkley-Black titration, texture by sieve and sedimentation.

Noise measurement uses a sound level meter in dB(A), with readings taken at fixed intervals and averaged.

A good project report includes aim, hypothesis, methodology, observations with tables and graphs, discussion, conclusion and references.