CBSE Class 12 Biology Environmental Issues Flow Chart

This Class 12 Biology flow chart for Chapter 16 Environmental Issues summarises nine environmental problems - air pollution, noise pollution, water pollution, solid wastes, radioactive wastes, greenhouse effect and global warming, ozone depletion, soil erosion and deforestation - with the source or cause, effect and control measures for each.

CHAPTER 16 - ENVIRONMENTAL ISSUES (FLOW CHART)

(1) AIR POLLUTION

Caused by: Particulate pollutant (2.5 mm causes harm), gaseous pollutant
Effect: Breathing, respiratory symptoms, inflammation, damage to lungs
PREVENTION: using CNG, catalytic converter, phasing out of old vehicles introducing Bharat stage EURO II norms, reducing sulphur in petrol and diesel to 50 ppm and 35%
CONTROL:
- Electrostatic precipitator: to remove particulate matter
- Scrubber: to remove gases like SO₂.
- Catalytic converter: metal like platinum, palladium, and rhodium converts unburnt hydrocarbons into CO₂ and H₂O

(2) NOISE POLLUTION

SOURCE: Automobiles, Loudspeaker, crackers, industry (150 db or more sound causes pollution)
EFFECT: Hearing impairment, sleeplessness, increased heartbeat, alters breathing
CONTROL: Using sound absorbent materials, delimiting horn free zones, permissible sound level of crackers and loudspeakers

(3) WATER POLLUTION

SOURCE: sewage and industrial effluent
Diseases like typhoid, jaundice, cholera, dysentery. Eutrophication, Bio magnification
CONTROL: Integrated waste water treatment (FOAM)

(4) SOLID WASTES

SOURCE: Municipal wastes, hospital wastes, electronic wastes, pesticides, weedicides, human excreta
EFFECT: causes diseases, soil pollution, kills beneficial insects and microbes
CONTROL: recycling, reuse, incineration, used for land filling, preparing

(5) RADIOACTIVE WASTES

SOURCE: Nuclear energy used for generating electricity
Radiation emitted cause mutations, genetic disorders in organisms
CONTROL: Storing in a shielded container after sufficient treatment and buried within the sea bottom or rocks about 500 m deep below the earth surface.

(6) GREEN HOUSE EFFECT AND GLOBAL WARMING

CAUSE: Gases like CO₂, methane, CFC, N₂O. Absorbs solar radiation and increase the atmospheric
El Nino effect - melting of polar ice caps, results in rise in sea level and submerges of coastal areas.
EFFECT: Reducing the emission of greenhouse gases, planting more trees, increasing efficiency of energy usage.

(7) OZONE DEPLETION

SOURCE: CFC released from refrigerator, AC, jet aeroplane degrades the ozone
Effect: UV rays act on CFCs and release Cl atoms which act as a catalyst and degrade ozone. Causes cataract, damage to DNA, aging of skin, skin cancer. UV-B causes snow blindness and inflammation of cornea.
CONTROL: preventing emission of CFC

(8) SOIL EROSION

CAUSE: Over cultivation, unrestricted grazing, Deforestation, Irrigation without proper drainage of
EFFECT: decreases soil fertility. water logging affect crops and draws salt to the surface of soil.
CONTROL: Planting more trees

(9) DEFORESTATION

CAUSE: Cutting trees for timber, fire wood. Convertion of forest to agricultural land. Slash and burn agriculture/jhum
EFFECT: global warming due to excess carbon-dioxide. Loss of biodiversity. Damage to hydrological cycle. Leads to soil erosion. Desertification of land
CONTROL: Reforestation.