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(a) The greenhouse gases such as CO₂ , N₂O, Methane present in the atmosphere will reradiate the reflected infrared radiations. Thus raising the temperature of earth.

(b) It will affect the climate of earth as the greenhouse effect causes melting of snow in the polar regions. This will in turn determine the level of water in the sea.

The International treaty called the Montreal Protocol (1987) was held in Canada on substances that deplete ozone layer and the main goal of it is gradually eliminating the production and consumption of ozone depleting substances and to limit their damage on the Earth’s ozone layer.

Chlorofluorocarbons (CFCs) break down in the presence of UV rays and produce active chlorine. The chlorine atoms break down ozone into molecular O₂, thereby depleting ozone layer.

Chipko movement was started in Garhwal, Himalayas in 1974 by Shri Sundar Lal Bahuguna to prevent cutting down of trees. The leaders of Chipko Movement believe in 5 Fs–food, fodder, fuel, fertilisers and fibres provided by the forest.

High concentrations of DDT disturb calcium metabolism in birds, which causes thinning of eggshell and their premature breaking, eventually causing decline in bird populations.

The excessive growth of certain phyto planktons, facilitated by the excess presence of nutrients in the water bodies is called algal bloom.

1. Decrease waste generation 

2. Use efficient transportation 

3. Reduce energy consumption 

4. Planting trees

Women and communities have played a crucial role in environmental conservation programmes.

Example 1: Chipko movement was started in 1974 in India. In this women from the village hugged the trees and prevented felling of trees by contractors.

Example 2: Amrita Devi, from Khejarli village of Jodhpur district, Rajasthan sacrificed her life to maintain Bishoni Dharma. Here the King of Jodhpur ordered his men to get the wood of Khejri trees by cutting them to construct his new palace. On hearing this Amrita Devi and many others had hugged the trees to save them from cutting. But her effort went on vain. Amrita Devi and others were killed by King’s men. This resistance by the people of village forced the King to give up the idea of cutting trees.

Reducing energy usage, Eat sustainable sea foods, use reusable plastic products, proper dispose of hazardous materials. Avoid littering on beach and buying ocean friendly products.

Forests decreases the CO₂ level and increase the oxygen level of atmosphere. Particulate matters in air will settle down on leaves. Thus they help to reduce water pollution.

Recycling prevents the emission of many greenhouse gases which are the major cause for global warming. It also reduces the water pollutants and save energy.

The primary purpose of Kyoto Protocol is to reduce the onset of global warming by reducing the concentration of green house gases in atmosphere.

Montreal Protocol, was signed at Montreal, in 1987 to curb the emission of ozone depleting substances.

1. The dissolved oxygen content is inversely proportional to BOD i.e. when BOD rises, the content of dissolved oxygen decreases and vice versa.
2. When BOD is high, the aerobic aquatic organism will die due to decreased availability of disolved oxygen. When BOD is low, the content of dissolved oxygen becomes high. In clear water, aerobic aquatic organisms reap

• CNG burns most efficiently in the automobiles and leaves very little of it unburnt.
• CNG cannot be adulterated like petrol/diesel
• It cannot be siphoned by thieves
• It is cheaper than petrol/diesel.

In Jhum cultivation, farmers clear the trees of the forest and burn the plant remains. The ash of the burnt vegetation contains minerals and is used as fertiliser. The land is then used for farming or cattle grazing. After cultivation, farmers move to another area and this process is repeated. Thus, in north-eastern states of India, this practice has caused major deforestation.

• Thermal power plants release both particulate and gaseous air pollutants from their smoke stakes.
• When they are inhaled, it cause breathing respiratory disorders, irritation and inflammation of lungs leading to premature death.
  Precausion
• By installing an electrostatic precipitator, more than 99% of the particulate matter will be absorbed.
• Scrubbers can be used to remove gaseous pollutants.

Human activities like over-cultivation, unrestricted grazing, deforestation and poor irrigation practices result in arid patches of land. The fertile top soil that may take centuries to develop is eroded due to these activities. When large barren patches extend and meet over time, a desert is created. Increased urbanisation is also one of the causes of desertification.

The plants growing near the boundary wall act as barriers for sound pollution and act as dust catchers.

Higher biological oxygen demand shows that the dissolved oxygen in water bodies is much reduced and thus aquatic animals will die. 

To allow the dust to fall.

Dobson (Unit) / D.U.

Control of global warming: 

• Reduce use of fossil fuel.
• Improving efficiency of energy usage. 
• Reducing deforestation.
• Promoting a forestation programme.
• Slowing down growth of human population.
• International initiative to be taken to reduce emission of green house gases. 

Desertification is a type of land degradation in which relatively dry land region becomes increasingly arid. 

Human activities responsible for desertification are as follows : 

(i) Deforestation (slash and burn and destruction of plants that retain water and shade land). 

(ii) Introduction of invasive species. 

(iii) Cattle grazing or overgrazing. 

(iv) Improper farming practices. 

(v) Excessive ploughing of land may also cause soil erosion.

'Bad‘ ozone formed in the lower atmosphere (troposphere) that harms plants and animals. 

There is 'good‘ ozone also; this ozone is found in the upper part of the atmosphere called stratosphere, and it acts as a shield absorbing ultraviolet radiation from the sun. 

The thickness of ozone layer is measured in terms of Dobson units (DU) 

Ozone (O₃) gas is continuously formed by the action of UV rays on molecular oxygen, and also degraded into molecular oxygen in the stratosphere. 

There should be proper balance of formation and degradation of ozone. 

Ozone depletion: 

• Balance of ozone in stratosphere is disrupted due to enhancement of ozone degradation by chlorofluorocarbons (CFCs). 
• CFCs find wide use as refrigerants. 
• CFCs discharged in the lower part of atmosphere move upward and reach stratosphere. 
• In stratosphere, UV rays acts on CFCs and release active Cl atoms. 
• Cl degrades ozone releasing molecular oxygen. 
• Cl acts as catalysts and not consumed during reaction. 
• Whatever CFCs are added to the stratosphere, they have permanent and continuing affects one Ozone levels. 
• The depletion is marked particularly over the Antarctic region. This has large area of thinned ozone layer, commonly called as the ozone hole.

Limiting production and consumption of chlorofluro carbon to half the level.

Montreal Protocol is an international treaty, that was signed at Montreal (Canada) in 1987 and become effective in 1989. The main .aim is to control the emission of a ozone depleting substances.

Effects of UV rays: 

• UV radiations shorter than UV-B are almost completely absorbed by Earth‘s atmosphere, if the ozone layer is intact.  
• DNA and proteins of living organisms are damaged by UV rays as they potentially absorb it. 
• The high energy of UV rays breaks the chemical bond in these molecules. 
• UV – B damages DNA and mutation may occur. 
• It causes ageing of skin.
• Damage skin cells and causes skin cancers. 
• In human eye cornea absorb UV – B radiation and high dose of UV – B causes inflammation of cornea called snow-blindness, cataract etc. 
• Such exposes may damage cornea. 

• Over Cultivation
• Poor irrigation practices
• Deforestation
• Unrestricted grazing.

The removal of top fertile layer due to human activities is called Soil erosion.

Reasons: 

• Over cultivation 
• Unrestricted grazing 
• Deforestation 
• Poor irrigation practices

Water logging and soil salinity:

• Irrigation with proper drainage, leads to water lodging in the soil. 
• Draws salt to the surface of the soil.
• The salt starts collecting at the roots of the plants. 
• The salt damages the roots and crop productions.

Conversion of forested areas to non-forested one. 

deforestation does occurs: 

• Slash and burn agriculture/jhum cultivation 
• Farmers cut down the trees of the forest and burn the plant remains. 
• Ash is used as fertilizer and land is used for farming or cattle grazing. 
• Later, Land is left uncultivated for several years for replenishment of minerals.

1. There are three main types of sources: point sources, non-point sources, leaks and spills. 

2. Point sources: Discharge of pollutants at specific locations through pipelines or sewers into the water body. Factory effluents, sewage, underground mines, oil wells, oil tankers and agriculture are common point sources. 

3. Non-point sources: Sources that cannot be traced to a single site of discharge like acid rain, dumping of the plastics in water bodies and agriculture chemical run off are common examples.

4. Leaks and Spills: This occurs mostly due to ship collision, off shore oil rigs, oil leakages and discharges into sea.

Deforestation is the destruction of forests in order to clear the land and make it available for other uses.

‘4R’ refers to Refuse, Reduce, Reuse and Recycle methods to manage plastic waste.

Air Quality Index (AQI) is a number used by government agencies to communicate to the public how polluted the air is at a given time. If AQI is between 0-50 then the quality of air is good.

Presence of large amounts of nutrients in waters causes excessive growth of planktonic (free-floating) algae, called an algal bloom.

Any kind of waste that contains infectious material generated by hospitals, laboratories, medical research centers, Pharmaceutical companies and Veterinary clinics are called medical wastes.

1. CFC: Chlorofluorocarbons 

2. AQI: Air Quality Index 

3. PAN: Peroxyacetyl nitrate

Biomagnification refers to increase in concentration of the toxicant at successive trophic levels.

1. RZWT : Root Zone Wastewater Treatment 

2. DEWATS : Decentralized Wastewater Treatment System

Chemical methods of wastewater treatment include:

1. Generation of insoluble solids. 

2. Produce an insoluble gas. 

3. Produce biologically degradable substances from a non-biodegradable substance.

4. Oxidize or reduce to produce a non objectionable substance.

1. uspended solids, e.g., Sand, silt and clay. 

2. Colloidal materials, e.g., Fecal matter, bacteria, cloth and paper fibres.

3. Dissolved materials, e.g., Nutrients (nitrate, ammonia, phosphate, sodium, calcium).

Recycling is the best solution for the treatment of electronic wastes.

Reforestation is the process of restoring a forest that once existed but was removed at some point of time in the past.

Reforestation is the process of restoring a forest that once existed but was removed at some point of time in the past.

Effects of deforestation :

• Leads to global warming due to excess carbon-dioxide.
• Loss of biodiversity. 
• Damage to hydrological cycle.
• Leads to soil erosion. 
• Desertification of land.

Restoring forest that was existing earlier E.g. Observing Van-Mahotsavas 

It also occurs naturally 

A forestation Developing a forest in a new area where no such forest existed in that area.