Scrubber. A scrubber can remove gases like sulphur dioxide. In a scrubber, the exhaust is passed through a spray of water or lime. Water dissolves gases and lime reacts with sulphur dioxide to form a precipitate of calcium sulphate or sulphite.

An electrostatic precipitator. It removes over 99% particulate matter present in the exhaust from a thermal power plant. It has electrode wires and a stage of collecting plates. The electrode, wires are maintained at several thousand volts, which produce a corona that releases electrons. These electrons attach to dust particles and give them a net negative charge within a very small fraction of a second. The collecting plates are grounded and attract the charged dust particles. The velocity of air between the plates must be low enough to allow the dust to fall.

An electrostatic precipitator. It removes over 99% particulate matter present in the exhaust from a thermal power plant. It has electrode wires and a stage of collecting plates. The electrode, wires are maintained at several thousand volts, which produce a corona that releases electrons. These electrons attach to dust particles and give them a net negative charge within a very small fraction of a second. The collecting plates are grounded and attract the charged dust particles. The velocity of air between the plates must be low enough to allow the dust to fall.

Role of Women
1. Amrita Devi Bishnoi showed exemplary courage to prevent the cutting down of trees by the king's men. She hugged a tree and the king's men cut down the tree along with her. Following this, her .three daughters and hundreds of other women lost their lives in saving the trees.
2. The Government of India has instituted the Amrita Devi Bishnoi wild life protection award for individuals or communities from rural areas that have shown extraordinary courage and dedication in protecting wildlife.
3. Women followed the same method to protect the trees in Garhwal Himalaya and initiated the Chipko movement.
4. Joint Forest Management (JFM) is a concept introduced by the Government of India (1980s) so as to work closely with the local communities for protecting and managing forests.

Catalytic Converter
1. Catalytic converters are used in automobiles for reducing emission of harmful gasses.
2. They have expensive metals like platinum, palladium and rhodium as catalysts.
3. As the exhaust passes through the catalytic converter, unburnt hydrocarbons are converted into carbon dioxide and water; carbon monoxide and nitric oxide are changed into carbon dioxide and nitrogen gas respectively.
4. Vehicles fitted with catalytic converter must use unleaded petrol as leaded petrol will inactivate the catalyst.

Biological Magnification is the phenomenon in which harmful chemical/pollutants get accumulated in the tissues of living organisms in increasing concentrations at successive trophic levels as they travel along the food chain.
1. When DDTwas used in a lake in USA to control mosquitoes, it was found that the phytoplanktons came to possess 800 times more DDT than that in the water of the lake.
2. Zooplanktons had about 5 times greater amount of DDT than phytoplanktons.
3. The fish population contained 9-40 times more DDT than zooplanktons.
4. The fish-eating birds had 25 times more than fish.

(i) Oxygen and nitrogen.
(ii) Electrostatic precipitator is used.
1. It is the most widely used method for removal of particulate matter; about 90% of particulate matter is removed from the exhaust of thermal power plants.
2. It has electrode wires and a stage of collecting plates.
3. The electrode wires are maintained at several thousand volts, which produce a corona that releases electrons.
4. These electrons get attached to the dust particles and give them a net negative charge within a very small fraction of a second.
5. The collecting plates are grounded and hence attract the charged particles.
6. The velocity of air between the plates must be low enough to allow the particles to fall on them.

Causes of global warming:
(i) Deforestation
(ii) Burning of fossil fuels
(iii) Excess use of nitrogenous fertilisers
(iv) Increased amounts of greenhouse gases(CO₂, CH₄, CFCs, N₂O).
It is a warning to humans because
(i) it leads to deleterious changes in the environment resulting in odd climatic changes.
(ii) it can lead to melting of polar ice caps and ice caps on mountain tops and result in a rise in sea level which can submerge many coastal areas.

Causes of global warming:
(i) Deforestation
(ii) Burning of fossil fuels
(iii) Excess use of nitrogenous fertilisers
(iv) Increased amounts of greenhouse gases(CO₂, CH₄, CFCs, N₂O).
It is a warning to humans because
(i) it leads to deleterious changes in the environment resulting in odd climatic changes.
(ii) it can lead to melting of polar ice caps and ice caps on mountain tops and result in a rise in sea level which can submerge many coastal areas.

1. When DDT is: sprayed on the crop plants, it remains in the soil as it is non-biodegradable and enters the plant.
2. As it travels through food chain, it undergoes biomagnification, i.e. increase in concentration at successive higher trophic levels, as it can neither be metabolised nor excreted; this causes disorders in those organisms.
3. In birds, a high concentration of DDT interferes with calcium metabolism and causes thinning of egg shells leading to their premature breaking; consequently there is a decline in bird population.

1. The natural ageing of a lake is called eutrophication. It is the biological enrichment of its water.
2. In a young lake, there is very little life and the water is cold.
3.  As time advances, the streams draining into it start adding nutrients like phosphates and nitrates.
4. They stimulate the growth of algae, phytoplanktons and some small plants.
5. So, the quantity of organic matter increases and the water becomes warmer and shallower; hence the decomposers start flourishing.
6. The decomposers flourish and make use of a large quantity of oxygen for decomposition.
7. This leads to depletion of dissolved oxygen of the water and mortality of fish and other aquatic organisms.
8. The eutrophied water bodies can lead to algal blooms, which further add organic matter and lead to oxygen depletion.

1. The natural ageing of a lake is called eutrophication. It is the biological enrichment of its water.
2. In a young lake, there is very little life and the water is cold.
3.  As time advances, the streams draining into it start adding nutrients like phosphates and nitrates.
4. They stimulate the growth of algae, phytoplanktons and some small plants.
5. So, the quantity of organic matter increases and the water becomes warmer and shallower; hence the decomposers start flourishing.
6. The decomposers flourish and make use of a large quantity of oxygen for decomposition.
7. This leads to depletion of dissolved oxygen of the water and mortality of fish and other aquatic organisms.
8. The eutrophied water bodies can lead to algal blooms, which further add organic matter and lead to oxygen depletion.

Scrubber
1. It is used to remove gases like sulphur dioxide from industrial exhaust.
2. The exhaust is passed through a spray of water or lime.
3. Water dissolves the gases and lime reacts with sulphur dioxide to form a precipitate of calcium sulphate or sulphite.

Heavy metals defined as those elements which hace a density of 5 > gcm^3.
e.g mercury, cadmium, copper and lead.

(i) Sleeplessness
(ii) Increased rate of heart beat
(iii) Altered breathing pattern.
(iv) Stress.
(v) Very high sound levels > 150 dB can cause damage to eardrum and permanent loss of hearing.
(iv) Chronic exposure to low level noise may also cause damage to hearing abilities.