Environment Chemistry

Environment Chemistry

Environment Chemistry is the branch of science which deals with the chemical changes taking place in the environment is known as environmental chemistry.

         the three main components of the environment are
     

biotic

 lt is a living component of the environment and includes man, plants and animals.

abiotic

lt is in the non-living component of the environment and includes atmosphere, hydrosphere, and lithosphere.

energy

 the energy component of the environment includes solar energy, hydroelectric, geochemical and nuclear energy.                           

Atmosphere

lt is the gas mixture that surrounds the earth. the main gases
present in the atmosphere are nitrogen(78%09) and oxygen (20.95%). other gases present in small amounts are CO2.helium, argon, etc.

Hydrosphere

 lt is the liquid phase of the earth in the form of sea and lakes. seawater is the source of large no. of elements present in the form of salts. 

Lithosphere

 It is the solid-phase of the earth which consists of different types of rocks, in which most of the elements are present in the form of minerals. the soil is the most important part of the lithosphere because plants grow in it.

Biosphere

 It is that part of the atmosphere, hydrosphere, and lithosphere. in which living organism lives together. A number of naturally occurring cyclic processes taking place in the environment keep a balance of different material present in the environment.
Example: Water Cycle, Oxygen Cycle, Nitrogen Cycle, Carbon Cycle.

Regions of Atmosphere

The Atmosphere above the surface of the earth is divided into four regions depending upon the temperature variation.


The most important region of the atmosphere is the troposphere. The temperature in the region decreases with the increase in heigh at becomes a minimum at 11Km. This is called Tropopause, After this point, the temperature again begins to increase in the next region. This is called a temperature inversion.

In the stratosphere, the ozone layer is present which absorbs harmful ultraviolet radiation from the sun and thus acts as an umbrella for these radiations. the region is also called the ozonosphere.

The mesosphere and thermosphere are also called ionosphere as they contain gases in ionized form.

Above the thermosphere, there is another region called the exosphere. Its height lies in the range of 500 to 1600Km. it mainly consists of oxygen, hydrogen, and helium.

The area beyond the exosphere is called interstellar space.

Environment Pollution

The presence of undesirable materials (i.e. air, soil, and water) beyond a certain limit that causes harmful effects is called as environment pollution.
The undesirable material in the environment is called as pollutants.
The air is polluted due to the presence of harmful gases like carbon oxide, sulphur dioxide, nitrogen dioxide, etc.
The soil is polluted due to the use of pesticides in excess.
The water is polluted due to the waste thrown in rivers, lakes, and sea by industries.

Thus we have disturbed the ecological balance of the environment with the advancement of technology and industrialization. For example, Methyl isocyanate (MIC) gas released from the factory was responsible for Bhopal Gas Tragedy in December 1984 that resulted in the loss of thousands of lives.

Cause of Pollution

1. The fast growth of Population.
2. Rapid urbanization
3. Release of Poisonous chemicals by industries.
4. Excessive uses of pesticides in agriculture.

Representation of pollution Model

The environment pollution may be represented as:

Contaminant And Pollutant

A contaminant is a substance that does not occur in nature but introduced by human activity. it may or may not be harmful to the living organisms.

The pollutant is a substance produced either by natural sources or by human activity to such extent that it has a harmful effect on Non-living or living organisms.

Threshold Limit Value. (TLV): The Permissible limit of a pollutant in an atmosphere that causes no adverse effects on a healthy person if exposed for 8 hours a day is known as threshold limit (TLV).
Example: TLV of CO is 40 ppm and that of CO2 is 5000 ppm.

Types Of pollutants

Primary and Secondary Pollutants:

Primary Pollutants: Primary Pollutants are those which remain as such in the environment after their formation
Example: Nitric oxide (NO).

Secondary Pollutants: Secondary Pollutants are those which are formed as a result of the chemical reaction between primary pollutants in the atmosphere
Example: peroxy acyl nitrated (PAN).

Biodegradable and Non-biodegradable Pollutants

Biodegradable pollutants are these materials which easily decomposed by the microorganism
Example: Cow dung, Domestic sewage, etc.
They are not harmful in small amounts, but if present in excess, they become pollutants.

Non-biodegradable Pollutants are those materials that do not undergo degradation by the microorganism.
Example: Mercury, Lead, D.D.T, etc.
They are harmful to living organisms even in a small amount.

Type of pollution

1. Air Pollution
2. Water Pollution
3. Soil Pollution

Air Pollution

The addition of undesirable materials to the atmosphere by natural phenomena or by human activity on earth that affects the quality of air is called air pollution.

Source of Air Pollution

The main source of air pollution are:

• Burning of fossils fuels like wood, coal etc which produces poisonous gases like Co, CO2, SO2, CH4, etc.
• Combustion of gasoline in automobiles which produces CO, NO, Lead and unburnt hydrocarbons.
• The fast increase in industries that produces a lot of non-biodegradable waste and a number of Oxygen(O2).
• Deforestation i.e cutting of trees that have resulted in the increase of CO2 in air and decrease of O2.
• An increase in population is also the major cause of pollution.

Tropospheric Pollution

The main pollutants in the troposphere are :

1. Oxide of carbon(Co and CO2)
2. Hydrocarbons (C%H8)
3. Oxide of nitrogen (BO2) and sulphur (SO3)
4. Particulates like dust, mist, smoke, smog, etc.

The harmful effect of CO

it is highly poisonous or toxic in nature. it is due to its tendency to combine with hemoglobin in blood to form stable complex carboxyhemoglobin.

Haemoglobin + CoO = Carboxy haemoglobin

This prevents hemoglobin from carrying oxygen in different parts of the body, which causes suffocation and ultimately leads to death.

Sink of CO

The level of CO in the atmosphere does not increase too much. This is because a significant amount of CoO is converted into CO2 by Microorganisms or bacteria present in the soil.
Thus the microorganism in the soil acts as a sink for CO.

The harmful effect of CO2

The increased level of CO2 in the atmosphere affects the respiration system and is responsible for the increase in global temperature. This is known as the Greenhouse effect.

Harmful effects of hydrocarbons

Certain hydrocarbons have harmful effects on human beings. they cause irritation in the eyes, nose, and lungs and also cause Cancer, CO2, a greenhouse gas is responsible for global warming. Some hydrocarbons react with ozone and oxide of nitrogen to form peroxyacetyl nitrates (PAN) that constitute photochemical smog.