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aditya sahoo

on 4 January 2014

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Transcript of Environment:-

effects of ozone depletion:-
Effects of depletion of the ozone layer:
With the depletion of ozone layer, more UV radiation filters into troposphere.
UV radiations lead to:
• Ageing of skin, cataract, sunburn and skin cancer etc in human beings
• Killing of many phytoplanktons
• Damage to fish productivity
• Affect the plant proteins which lead to the harmful mutation of cells
• Increases the evaporation of surface water through the stomata of the leaves and decreases the moisture content of the soil
• Increase in UV radiations damage paints and fibres, causing them to fade faster
Biochemical Oxygen Demand (BOD): The amount of oxygen required by bacteria to break down the organic matter present in a certain volume of a sample of water is called BOD
Stratergies to control Environmental pollution
a. Viable are minute living organisms that are dispersed in the atmosphere. Example: bacteria, fungi, moulds, algae etc.
b. Non-viable particulates may be classified as:
Smog is of two types:
Classical Smog;

1. It occurs in cool humid climate.
2. It is a mixture of smoke, fog & sulphur dioxide.
3. It is also called reducing smog.
Photochemical smog;-
1. It occurs in warm, dry and sunny climate.
2. Components of photochemical smog result from the action of sunlight on unsaturated hydrocarbons & oxides of nitrogen produced by automobiles & factories.
3. It is also called oxidizing smog.
Environmental pollution: It is the effect of undesirable changes in our surroundings that have harmful effects on plants, animals and human beings.
i. Smoke particulates: consist of solid or mixture of solid and liquid particles formed during combustion of organic matter.
Example: cigarette smoke, smoke from burning of fossil fuel, garbage and dry leaves, oil smoke etc.
ii. Dust: composed of fine solid particles (over 1μm in diameter), produced during crushing, grinding and attribution of solid materials. Sand from sand blasting, saw dust from wood works, pulverized coal, cement and fly ash from factories, dust storms etc., are some typical examples of this type of particulate emission.
iii. Mists: Are produced by particles of spray liquids and by condensation of vapours in air. Example: sulphuric acid mist and herbicides and insecticides that miss their targets and travel through air and form mists.
iv. Fumes: Are generally obtained by the condensation of vapours during sublimation, distillation, boiling and several other chemical reactions. Generally, organic solvents, metals and metallic oxides form fume particles
Effects of photochemical smog:
• Ozone and PAN act as powerful eye irritants.
• Ozone and nitric oxide irritate the nose and throat and their high concentration causes headache, chest pain, and dryness of the throat, cough and difficulty in breathing,
• Photochemical smog leads to cracking of rubber and extensive damage to plant life.
• It also causes corrosion of metals, stones, building materials, rubber and painted surfaces.
a. Water management
• Segregate the water as biodegradable and non- biodegradable waste:
􀂾 Biodegradable waste:
􀀹 Generated by cotton mills, food processing units, paper mills, and textile factories.
􀀹 Management: are deposited in landfills and are converted into compost
􀂾 Non – biodegradable water:
􀀹 Generated by thermal power plants which produce fly ash; integrated iron and steel plants which produce blast furnace slag and steel melting slag
􀀹 Management:
- Recycling
-Toxic wastes are usually destroyed by controlled incineration

2. Pollutant: A substance, which causes pollution, is known as pollutant
3. Pollutants can be solid, liquid or gaseous substances present in greater concentration than in natural abundance
4. Pollutants can be natural or anthropogenic:
a. Natural pollutants: These are produced due to natural happenings like volcano eruptions etc.
b. Anthropogenic pollutants: These are produced due to human activities
5. Pollutants can be biodegradable or non – biodegradable:
a. Biodegradable pollutants: These are the pollutants which rapidly break down by natural processes. Example: discarded vegetables
b. Non – biodegradable pollutants: These are the pollutants which are slowly degradable, and remain in the environment in an unchanged form for many decades. For example: DDT, plastic materials, heavy metals, many chemicals, nuclear wastes etc
6. Environmental pollution is of three types:
a. Atmospheric pollution
i. Tropospheric pollution
ii. Stratospheric pollution
b. Water pollution
c. Soil and land pollution
7. Atmospheric pollution occurs when the concentration of a normal component of the air or a new chemical substance added or formed in air builds up to undesirable proportions causing harm to humans, other animals, vegetation and materials
Troposphere: The lowest region of atmosphere in which the human beings along with other organisms live is called troposphere. It extends up to the height of ~ 10 km from sea level
9. Stratosphere: Above the troposphere, between 10 and 50 km above sea level lies stratosphere.
10. Tropospheric pollution: Is because of two types of pollutants:
a. Gaseous air pollutants: These are oxides of sulphur, nitrogen and carbon, hydrogen sulphide, hydrocarbons, ozone and other oxidants.
Oxides of nitrogen as pollutant:
• At high altitudes when lightning strikes, dinitrogen and dioxygen combine to form oxides of nitrogen.
• Burning of fossil fuel in an automobile engine, at high temperature, dinitrogen and dioxygen combine to yield significant quantities of nitric oxide (NO) and nitrogen dioxide (NO2).
N2 (g) + O2 (g) 1483K⎯⎯⎯⎯⎯→ 2 NO (g)
2 NO (g) + O2 (g) → 2 NO2 (g)
Harmful effects:
• Damage the leaves of plants and retard the rate of photosynthesis
• Nitrogen dioxide is a lung irritant that can lead to an acute respiratory disease in children
• It is toxic to living tissues also
• Nitrogen dioxide is also harmful to various textile fibres and metals
Green house effect: About 75 % of the solar energy reaching the earth is absorbed by the earth’s surface, which increases its temperature. The rest of the heat radiates back to the atmosphere. Some of the heat is trapped by gases such as carbon dioxide, methane, ozone, chlorofluorocarbon compounds (CFCs) and water vapour in the atmosphere. Thus, they add to the heating of the atmosphere. This causes global warming.
This trapping of the sun’s heat near the earth’s surface and keeping it warm is called natural greenhouse effect. It maintains the temperature and makes the earth perfect for life.
If the amount of carbon dioxide crosses the delicate proportion of 0.03 per cent, the natural greenhouse balance may get disturbed. This may lead to global warming.
16. Green house: In a greenhouse, visible light passes through the transparent glass and heats up the soil and the plants. The warm soil and plants emit infrared radiations. Since glass is opaque to infrared (heat) radiations, it partly reflects and partly absorbs these radiations. This mechanism keeps the energy of the sun trapped in the greenhouse.
Global warming: An increase in the average temperature of the earth's atmosphere (especially a sustained increase that causes climatic changes) which may be caused by additional heat being trapped by greenhouse gases.
18. Acid rain: Normally rain water has a pH of 5.6 due to the presence of H+ ions formed by the reaction of rain water with carbon dioxide present in the atmosphere.
Harmful effects:
• Harmful for agriculture, trees and plants as it dissolves and washes away nutrients needed for their growth.
• Causes respiratory ailments in human beings and animals.
• Affects plant and animal life in aquatic ecosystem when acid rain falls and flows as ground water to reach rivers, lakes etc.
• Corrodes water pipes resulting in the leaching of heavy metals such as iron, lead and copper into the drinking water.
• Damages buildings and other structures made of stone or metal. The Taj Mahal in India has been affected by acid rain.
particulates in the atmosphere may be viable or non-viable;-
Control of photochemical smog:
• Use of catalytic converters in automobiles, which prevent the release of nitrogen oxide and hydrocarbons to the atmosphere.
• Certain plants e.g., Pinus, Juniparus, Quercus, Pyrus and Vitis can metabolise nitrogen oxide and therefore, their plantation could help in this matter.
Depletion of ozone;-
Depletion of ozone layer:
Release of chlorofluorocarbon compounds (CFCs), also known as freons lead to their mixing with the normal atmospheric gases and eventually reach the stratosphere.
Stratospheric pollution is basically due to ozone layer depletion
In summer season, nitrogen dioxide and methane react with chlorine monoxide and chlorine atoms forming chlorine sinks, preventing much ozone depletion.
ozone depletion over antartica
Eutrophication: The process in which nutrient enriched water bodies support a dense plant population, which kills animal life by depriving it of oxygen and results in subsequent loss of biodiversity, is known as eutrophication.
pesticides and herbicides
Pesticides: They are basically synthetic toxic chemicals with ecological repercussions
Herbicides: They are used to kill weeds or undesirable vegetation. Example: sodium chlorate (NaClO3), sodium arsinite (Na3AsO3)
Green chemistry
Green chemistry: Green chemistry is a strategy to design chemical processes and products that reduces or eliminates the use and generation of hazardous substances. The chemical reactions should be such that the reactants are fully converted into useful environmental friendly products by using an environment friendly medium so that there would be no chemical pollutants introduced in the environment.
Made By:-

Class - XI-"A"

"Once there were brook trout in the streams in the mountains. You could see them standing in the amber current where the white edges of their fins wimpled softly in the flow. They smelled of moss in your hand. Polished and muscular and torsional. On their backs were vermiculate patterns that were maps of the world in its becoming. Maps and mazes. Of a thing which could not be put back. Not be made right again. In the deep glens where they lived all things were older than man and they hummed of mystery.”
― Cormac McCarthy, The Road

“Earth provides enough to satisfy every man's needs, but not every man's greed.”
― Mahatma Gandhi

We need the tonic of wildness...At the same time that we are earnest to explore and learn all things, we require that all things be mysterious and unexplorable, that land and sea be indefinitely wild, unsurveyed and unfathomed by us because unfathomable. We can never have enough of nature.”
― Henry David Thoreau, Walden: Or, Life in the Woods
“The poetry of the earth is never dead.”
― John Keats

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