WHAT IS GLOBAL WARMING?

GLOBAL WARMING

• The gradual slow rise in the temperature of the earth due to emission of excess quantities of radiation and trapping gases is called the global warming.
• The green house gases absorb the radiated heat or re- radiated rays of sun and re emits to the earth's surface again to maintain optimum temperature at the earth's surface in troposphere. This is called the green house effect. But due to raid industrialization and population growth and transportation, the rate of emission of green house gases especially carbon dioxide and methane is increasing and this phenomena results in a slow and gradual rise in temperature. Thus, the excess green house gases is responsible for global warming.

Effects of global warming 

1. Effect of global warming on climate :

Due to increase of average global temperature, water from various sources on earth may evaporate more rapidly due to this phenomena, the amount of rain fall may increased. However this phenomena will not occur evenly in all places. Some place may be rainfall heavily and some places suffering drought. In some region summer may be hotter and prolonged and winter becomes warmer and shorter.

2. Effect of global warming on sea water level :

When the global temperature increases, the ice caps and glaciers region of earth may be melted partially. The floating ice on water of sea also get melted. Due to this phenomena, The overall level of sea may be submerged into water and population at coastal area should be migrate.

3. Effect of global warming on agriculture :

An increase in the amount of carbon dioxide may increases the photosynthesis phenomena of plants so it will be increase in crop as well as but the high temperature due to green house gases can adverse effect on dry soil. It will decrease the fertility of soil and on the other hand, due to heavy rain, soil may be get erosion and due to drought the crop may be get deterioration.

4. Effect of global warming on marine organisms:

Due to increased in temperature, the ice caps and glaciers melts and as a result the volume of sea water will be expand. This expansion reduces concentration of salt and change the PH value of sea water. This change is not suitable for various existence living organisms and they get disturbed.

5. It will be results into acid rain which affect eco system.

6. Depletion of ozone layer.

7. The existing precipiration pattern get disturbed.

8. Change in climate, humidity and weather due to this ecological imbalance occurs.

Steps to control global warming :

1. Reduction in consumption of fossil fuels such as coal and petroleum.
2. Change the conventional energy generate system. Increase the use of renewable sources to generate electricity.
3. Replace the fuel engines by electric engines.
4. Stop deforestation and grow the trees as per ratio required in area.
5. Increase efficient use of solar energy.
6. Make proper formation for industrial effluents.
7. Check permissible values of gases which is escape by the industries.
8. Plan appropriate design for recovery of green house gases.

DEVICES TO CONTROL AIR POLLUTION.

• The following devices are commonly used as pollution control devices by industry or transportation devices. They can either destroy contaminants or remove them from an exhaust stream before it is emitted into the atmosphere.

1. Settling chamber
2. Cyclone separator
3. Bag filter
4. Electrostatic precipitator
5. Catalytic converter
6. Ventary scrubber

• These are used to enrich the quality of air by arresting the impurities present in the dust air.
• The central pollution control board recommanded a limiting value for each particulate matter.

Category               SPM          SO2            NOx          CO

Industrial                500           120           120          5000

Residential             200             80             80          2000

Sensitive area        100             30             30          1000

Note :  Limiting value measured in Ug/ Nm3.

1. Settling chamber :

• The settling chamber is the simplest type of equipment used for collecting of solid particulates.
• It consists of a chamber in which the gas has to flow from the inlet and descend from the outlet. Among this process velocity of gas is reduced so the particulate matter of gas is reduced so the particulate matter are allow to settle down in the hopper due to gravity and form there the PMs are removed.

Advantages :

• Low initial cost
• Simple construction
• Low maintenance cost
• Low pressure drop
• Dry and continuous disposal of solid particles.

Disadvantages :

• Large space requirement 
• Comparatively large particles can be collected only.

2. Cyclonic separator :

• Cyclonic separator utilizes a centrifugal force which is generated by spinning gas stream in the chamber. This process separates the particulate matters from the carrier gas and the carrier gas flow upward in the chamber whereas the particulate matters go down in the hopper due to gravitational force action.
• This process are more effective to remove small size particulate matters than the settling chamber.
• These chambers are shaped like an upside-down cone to promote the collectively of these particulate matters at bottom and cleaned gas escapes from the top of the chamber.

Advantages :

• Low initial cost
• Simple construction
• Low pressure drop
• Low maintenance
• Continuous disposal of solid particles
• Small particulate matters can be collect

Disadvantages :

• Low collection efficiency
• Equipment is subjected to abrasive deterioration.

3. Bag filter/ Fabric filter :

• The bag filter is also known as bag house filter. This system typically comprises a tubular bag which suspended or mounted in a chamber. The structure in which the bags hung is known as bag house.
• Generally dirty gases enters in the bag house and the air is passing through the fabric tubular bag which collect the particulate matters and run the clean air upward where it is escape from the chamber whereas the particulate matters collect by the tubular bag which is further shaking at the fixed intervals of time. While shaking the bag, the PM are fall downward and collected in hopper.

Advantages :

• Very high efficiency
• Retention of fine particles.
• Collection of solid fine particles in dry form.
• Relatively low pressure drop
• Small and fine particles can be collected

Disadvantages:

• Requirement of large space for process
• High construction cost
• Operation below 285 C of the carrier gas.

4. Electrostatic Precipitator :

• Electrostatic precipitator can be defined as a type of air cleaner or filter that utilizes electric energy for removing the impurities, dust particles from the air.
• It consists vertical wire which is placed in between parallel plates. A strong electric field is created between the wires and the plates by impressing a high negative voltage on the wires. The negatively changed electrode generates free electrons which move towards the plate and on the way it attach some particulate matters. The particles now carry a charge which cause them to move under the influence of the electric field to the surface of the plates. Eventually, they are removed by the gravitational action or by the flashing the collecting plates with liquid.

Advantages :

• Less power consumption
• Economical and easy to operate
• Highly efficiency obtained
• Very fine particles can be collect

Disadvantages :

• High initiate cost
• Large space required
• Required skill person for operating due to high voltage operations.

5. Catalytic converter :

• Catalytic ocnverter is the most modern car equipped with three way converter. The three way refers to that the device converts three harmful compounds in car exhaust into the harmless compounds.
• These harmful compounds are carbon monoxide, Volatile organic carbon and oxides of the nitrogen.
• To convert these compounds into harmless compound it uses two different type of catalysts namely, reduction catalyst and oxidation catalyst.
• Usually platinum, rhodium and palladium are used as catalysts.

• In the catalytic converter, three steps are used. 

1. Reduction 
2. Oxidation 
3. Control system

1. Reduction :

In this step, the platinum and rhodium are used as catalystis. In this step, oxides of nitrogen are converted into harmless nitrogen molecule as follows.

               2NO    -----  N2 + O2

               2NO2   -----  N2 + 2O2

2. Oxidation :

In this step,the plantinum and palladium are used as catalyst. In this step, carbon monoxide and volatile organic carbon are converted into carbon dioxide as per the following reactions.

                       2CO + O2 -------- 2CO2

               4HC + 5O2 ------- 4CO2+2H2o

3. Control system :
The third step of catalyst converter is control stage. In which, air to fuel ratio is controlled eith the help of oxygen sensor. This sensor is placed upper in the catalyst converter. It manages the oxygen and follows the increase and decrease of oxygen as per requirement.

Advantages :

• Reduction of harmful gases emitted into atmosphere.
•  Small size and easy mechanism inside the car.

Disadvantages :

• 
  

  High initial cost
• High maintenance
• Require high temperature for proper functioning.

DISCUSS ABOUT SOME AIR POLLUTANTS.

Air pollutants are classified in two aspects.
1. Primary air pollutants
2. Secondary air pollutants
Primary pollutants are substances directly emitted from a process, such as ash from a volcanic eruption, the carbon monoxide gas from a motor vehicle exhaust and sulphur dioxide released from factories.

Secondary pollutants are not emitted directly. Rather, they form in the air when primary pollutants react or interact. An important example of a secondary pollutant is ground level ozone — one of the many secondary pollutants that make up photochemical smog. The details of each pollutants are discuss below.

1. CO [Carbon monoxide] :

• Carbon monoxide is produced by the incomplete combustion of carbon-containing fuels, such as gas (domestic or bottled), coal, oil and wood. In short, it forms when there is not enough oxygen to produce carbon dioxide. Vehicular exhaust is a major source of carbon monoxide.
• Carbon monoxide is a deadly poisonous gas in high concentration.If its value reaches above the permissible value than it will be very harmful for human health.
• Carbon monoxide is colorless, odorless, and tasteless, but highly toxic. 
• The chief sources of this gas are combustion of automobiles, furnaces, domestic fires, forest fire, coal in factories, houses and power plants etc.

• Effects of carbon monoxide on human being.

1. Carbon monoxide reduces the oxygen carrying capacity of hemoglobin of human blood cells.
2. Its presence in air even small amount may cause headache, breathing trouble and vomiting tendency.
3. It can also occur food poising in human being.
4. Exposures to carbon monoxide may cause significant damage to the heart and central nervous system.

Main sources of carbon monoxide (CO) :

1. Automobiles                         CO emission

 (i)   Transportation                          64%

 (ii)  Motor vehicles                          59.5%

 (iii)  Air crafts                                   2.5%

 (iv) Rail roads                                  1.0%

2. Industrial process

Iron steel, paper and 

petroleum industries                         9.6%

3. Other sources

 (i)  Forest fires                                  6.9%

 (ii) Agriculture burning                      8.3%

2. HC [Hydro carbon] :

• Hydro carbon present in the air is primary air pollutant. Unburnt or partially burnt gasoline or petroleum are the main source of hydrocarbons. Decomposed organic waste and garbage also produce hydrocarbons. It is methane, ethane and propane.

Effects of hydrocarbon (HC) on plants and man.

1. Damage to bological system
2. Cause leaf damage to sensitive plants.
3. HC has several effects on human lungs.
4. It causes irritation to eyes, nose and throat.

3. Sulphur dioxide (SO2)

• SO2 is produced by volcanoes and in various industrial processes. Since coal and petroleum often contain sulphur compounds, their combustion generates sulphur dioxide. Further oxidation of SO2, usually in the presence of a catalyst such as NO2, forms H2SO4, and thus acid rain. This is one of the causes for concern over the environmental impact of the use of these fuels as power sources.
• The chief source of SO2 emission are given below:

1. Burning of fossil fuels

2. Automobiles

3. Chemical industries

4. Oil and petroleum refineries

5. Forest fire

6. Volcanic eruption

• Effects of SO2 on man and plants

1. The plant leaf is changed to yellowish color.
2. It damages biochemical of plants.
3. Oxides of sulphur when absorbed by rain water forms sulphuric acid (H2SO4) which is harmful for environment.
4. SO2 reaching to the lungs cause respiratory problems.
5. Inhaling of his odour gas cause headache and irritation to eyes.
6. It increases the rate of corrosion of iron, steel, aluminum etc.

4. Nitrogen oxide (NOx)

• There are several oxides of nitrogen present in atmosphere. They are primary air pollutant. These are nitrous oxide, nitric oxide, nitrogen dioxide, dinitrogen trioxide, dinitrogen tetroxide, dinitrogen pentoxide and nitrogen trioxides. In which, NO and NO2 are the most important primary air pollutants.
• Combustion of fossil fuels, i.e coal and petroleum produce about 90% of oxides of nitrogen which emits in atmosphere.
• Denitrification process by bacterial activity also emits small amount of NO and NO2 in atmosphere. In which 95% of NO and 5% of NO2.
• Contribution of NO in the formation of photochemical smog is important. NO plays an important role in the formation of several photochemical pollutants such as PAN (Peroxyl acteyl nitrate) and O3 ozone.

• Source of NO and NO2 :

1. Combustion of fossil fuels.
2. Automobile exhausts
3. Forest fires 
4. Electric generation plants 
5. Smelting plants 
6. Industrial boilers 
7. Petroleum refineries

• Effects of NO and NO2 :

1. Erosion of metal surface.
2. Reduction in visibility.
3. Irritation in eyes, nose and throat.
4. Adversely affect kidney, heart and liver at high concentration.
5. Inhibition of growth of plants.

5. Particulate matters (PM) :

• Particulate matters are the third largest category of air pollutants. They are small pieces of solid materials which include fine liquid droplets. They diffuse into the atmosphere and called aerosols. In short, aerosols are mixture of particles and gas together.
• Sources of particulate matter can be manmade or natural. Some particulates occur naturally, originating from volcanoes, dust storms, forest and grassland fires, living vegetation, and sea spray. Human activities, such as the burning of fossil fuels in vehicles, power plants and various industrial processes also generate significant amounts of aerosols.
• Particulate matters are quickly recognized because they are easily detected by the human eyes. For example heavy black smoke can be seen with naked eyes, whereas carbon monoxide and sulphur dioxide goes unnoticed because the emission of these gases are colorless.
• There are different types of particulate matters are present in an atmosphere. They are collectively known as Suspended particulate matters (SPM). Among them, the particulate matters which are respirable particulate matter (RPM) and remaining part is known as Residual dust (RD).
• Effects of particulates :

1. PM are responsible for different ENT disease and serious damage to lungs.
2. Different  metallic particles like cadmium, lead, cobalt etc and their compounds cause various pulmonary and cardiac disease.
3. Main particulate matters being washed by rain and fall on soil and affect the soil fertility.
4. These particulate matters may reduces the photosynthesis of plants.
5. Respiratory system can be damaged directly by particulate matter that enter the blood system through lungs.

5. Volatile organic compounds:

• VOCs are an important outdoor air pollutant. In this field they are often divided into the separate categories of methane (CH4) and non-methane (NMVOCs). Methane is an extremely efficient greenhouse gas which contributes to enhanced global warming.
• Other hydrocarbon VOCs are also significant greenhouse gases via their role in creating ozone and in prolonging the life of methane in the atmosphere, although the effect varies depending on local air quality. Within the NMVOCs, the aromatic compounds benzene, toluene and xylene are suspected carcinogens and may lead to leukaemia through prolonged exposure. 1-3 butadiene is another dangerous compound which is often associated with industrial uses.

WHAT IS AIR POLLUTION?

• Air pollution can be define as the presence of one or more contaminants in the atmosphere in such a quantity and its duration and its concentrations in the atmosphere tends to injurious to health of humans, animals, plants and other living organisms.
• There are mainly two types of air pollutants which spreads air pollution in atmosphere.

1. Primary air pollutant : 

Primary air pollutants are those which directly emitted from the identified source. For example CO2, NO, NO2, HC, CFCs etc.2. Secondary air pollutant :

Secondary air pollutants are those which are produced in air by the interaction among two or more primary pollutants. For example Sulphuric acid, nitric acid, PAN (Peroxyl acteyl nitrate) etc.

• Types of air pollution spread by different aspects.

1. By natural (Pollen grain)
2. By particulate matter
3. By gases (SO2, NOx, CO2, CO, O3, Hydrocarbon)
4. By others like dust, smoke, mists, fog, fumes.

WHAT IS ENVIRONMENT DEGRADATION?

• Environment degradation of the environment means the deterioration of the environment through depletion of resources such as air, water and soil or any undesirable change in ecosystem.
• It may arise either by natural processes such as landslides, earthquakes, tsunamis etc. or by man made activities such as deforestation, industrialization, fossil fuel consumption etc.
• Environment degradation is mainly affected by environment pollution spreads by human being for self interest and profits.
• Environment degradation is affected by following things.

1. Deposited matters (Smoke, dust, grit)
2. Gases (NO, NO2, SO2)
3. Acid droplets (Sulphuric and nitric acid)
4. Metals (Mercury, lead and iron)
5. Agro-chemicals (Biocides, pesticides, fungisides)
6. Complex organic substance
7. Fluorides
8. Solid waste
9. Radioactive waste
10. Unwanted noise
11. Global warming
12. Deforestation
13. Disposal of industrial effluents

• Above all pollutants are classified as air pollution, water pollution, soil pollution and noise pollution.

• Environment degradation can be controlled by  few possible measures to manage environment degradation.

1. Environmental problems should be imparted to general public through the news and media.
2. Environment education must be made compulsory for every citizen.
3. Protection of environment must be enforced by proper law implementation.
4. Proper and specific standards must be made for pollutants.
5. Nuclear testing which produce radioactive waste should be restricted to minimum as per IAEA.
6. All factories, industries, power plants and airports must be placed for away from the cities to minimize pollution.
7. Wild life and flora and fauna must be preserved at any cost to save biodiversity.
8. Limit the use of pollution devices in industries and factories.

Types of pollution may be categorized under six major heads.

1. Water pollution
2. Soil pollution
3. Air pollution
4. Thermal pollution
5. Noise pollution
6. Pollution by radio-active substance

WHAT IS GREEN HOUSE EFFECT? iTS CAUSES, CONSEQUENCES AND CONTROL MEASURES.

• The green house effect is a natural process that warms the earth's surface. When the sun's energy or rays are reaches to the earth's atmosphere, some of its reflected back to space and the rest is absorbed and re-radiated by green house gases.
• Green hose gases includes water vapor, carbon dioxide, methane, nitrogen dioxide and some chemical components such as CFCs.
• The absorbed energy of sun warms the atmosphere and surface of earth. his process maintains the earth's temperature at around 33 C. Warmer than it would otherwise be, allowing life on earth to exist.

• Causes of green house effect :

1. Emission of carbon dioxide from the combustion of coal.
2. Deforestation
3. Chloroflurous carbon
4. Molecule of co.
5. Carbon cycle.

• Consequences of green house effect

1. More drought and more flooding.
2. Increases sea level.
3. Rising extreme weather condition.
4. More radiation penetrates in atmosphere.
5. Rise in global warming.
6. Spread the disease in human organisms.

• Steps to control green house effect

1. Afforestation
2. Social forestry
3. Extensive use of flyash
4. Reduce combustion of coal
5. Replacement of CFCs with mono-oxide
6. Replace transportation techniques

STEPS TO REDUCE OZONE DEPLETION.

Following steps to be taken to prevent ozone layer depletion.

1. Elimination of CFCs in environment.

2. Find or develop the substitute of CFCs which are less dangerous for ozone layer.

3. Limit an exploitation of natural resources such as fossil fuels and coal.

4. Control the emission of toxic gases and pollutants into atmosphere.

5. Stop the mad race among the nations over the development which affect the sustainable development.

6. Follow earth summit -R10 conference observations and beliefs which are given below.

(i) Follow steps for the protection and sustainable use of world's diverse plants and animal species.

(ii) Reduce emission of gases which are believed to be contributing global warming.

(iii) Management, conservation and sustainable development of all type of forests.

(iv) Turns the nations towards more environmentally sustainable patterns of development.