There are different layers of the atmosphere, but we are concerned about two lower layers that are troposphere and stratosphere for atmospheric pollution.
In the troposphere:
- The first layer extends up to 10 km from sea level. All the organism including human being live;
- The troposphere is turbulent, dusty zone, contains water vapor, clouds.
- Strong air movement and formation of clouds happen.
- It contains nitrogen, oxygen, water vapors.
- The ozone layer is present which prevents 99.5 % of ultraviolet ( UV) radiation from reaching the earth's ground.
Tropospheric Pollution:
Pollution occurs due to undesirable solid and gas particles present in the air.
- Gaseous air pollutants:
- Oxides of Sulfur, Nitrogen, Carbon, Hydrogen, hydrocarbon, ozone.
- Particulate pollutants;
- Dust, mist, smoke, smog.
Oxides of Sulphur:
- Produced when fossil fuel burned
- Sulfur dioxides are poisonous to animals and plants.
Effects:
- Respiratory disease such as Asthma
- Irritation to eyes and redness
- Stiffness of flower buds
Oxides of Nitrogen:
- Nitrogen and Oxygen are the main contributors to the atmosphere, but they do not mix at the normal temperature.
- When lighting strick, it forms No2, No3 minus nitrate; these form as a natural fertilizer.
- In automobile engine; at high temperature; fossil fuel burned; Nitric oxides and nitrogen dioxide formed.
Effects of oxides of Nitrogen:
- Red haze in the traffic
- Damage leaves of plants and slow rate of photosynthesis
- Acute respiratory disease in children
- Harmful to textile fiber and metal
Hydrocarbons:
- It is composed of hydrogen and carbon.
- It is formed by the incomplete combustion of fuel used in automobiles
Effects:
- Cancerous
- Cause aging
- Break down of tissues and shedding of leaves and flow.
Oxide of Carbon:
These are:
Carbon Monooxides( CO):
- CO is released due to the incomplete combustion of carbon by automobiles, coal, firewood, petrol.
- It is the most serious air pollutants
- It is coulourless and odourless gas
- Highly poisonous for the living organism
- When it reaches the blood, it formed Carboxyhaemoglobin which greatly reduced the oxygen-carrying capacity of the blood.
Carbon dioxides( Co2):
- It is released by respiratory, burning of fossil fuels for energy, manufacturing of cement during decomposition of limestone, and volcanos eruptions.
- Co2 composition is 0.03 % in the atmosphere.
- Due to the increment of Co2 emissions and reduction of green cover of earth, the share of Co2 is rising in the atmosphere.
Methane:
- Methane is produced when vegetation is burned, vegetation in the absence of oxygen, from paddy fields, coal mines, etc.
CFCs:
- CFC is produced in the industrial chemicals used in air conditioners, it depletes the ozone layer.
Issues relating to air pollution:
- Human and Animal Health issues
- Increase in Epidemics
- Biodiversity losses
- Global warming and the greenhouse effect
- Climate changes
- Sea level rise
- Acid rains
- Smog
- Ozone layer depletion
Global warming and greenhouses effects:
Some atmospheric gases trap heat by carbon dioxide, methane, ozone, chlorofluorocarbon compounds( CFCs), and water vapor.
These greenhouse gases are good as they make them warm during the night. But high concentrations of these greenhouse gases increase the overall temperature which creates other problems such as:
- Melting of a polar glacier
- Sea level rising
Acid Rains:
- Normal rainwater generally has Ph 5.6. If the rainwater ph value gets lower by 5.6, is called acid rains.
- It comes down to the form of dry deposition, water, fog, and snow.
- It is formed by oxides of nitrogen, hydrogen, and sulfur.
- It s also harmful to vegetation, animal, metals, and building.
Smog:
Smog= smoke + fog.
Two types of smog:
Classical smog:
- Classical smog in a cool humid climate formed by a mixture of smoke, fog, and sulfur dioxides.
Photochemical smog:
- It occurs in a warm and dry climate with the presence of sunlight.
- Unsaturated hydrocarbon, nitrogen oxides produced by automobiles and factories in the presence of sunlight.
Ozone layer depletion:
- The ozone layer is present in the stratosphere which prevents the UV ray to reach the earth's surface.
- Ozone gas is produced by Oxygen molecules in the presence of UV.
- The presence of CFCs( Chlorofllo carbon) was increasing in the stratosphere.
- CFC broke down in gree chlorine in the presence of UV.
- Free chlorine reacts to ozone and forms oxygen, which leads to the depletion of ozone gases.
Summer season above Antarctica :
- Nitrogen oxide and methane react with chlorine atoms and reduce the free chlorine; which prevents the ozone layer depletion.
In Winter,
- Polar stratospheric clouds form in Antarctica which adds free chlorine and increases the ozone layer depletion.
- Cause aging of skin and skin cancer
- Phytoplankton kills
- Damaging fish productivity
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