Environmental Pollution

Environmental Pollution

It is very essential to know about environmental pollution, but before starting the environmental pollution. We should discuss exactly what is the environment? The environment means the surroundings, the whole physical & biological system in which human & other living organisms live & survive.

The environment has 4 main components

  • Atmosphere
  • Hydrosphere
  • Lithosphere
  • Biosphere
  1. Atmosphere:

The atmosphere is a flow system of gases, suspended particle & water vapours. These gases are commonly known as air which surrounds our planet earth and is retained by the gravity of earth.

Air contains 78.09% nitrogen, 20.95% oxygen 0.93% organ 0.04% carbon dioxide and other gases in small quantity. Air also contains a variable amount of water vapour on average around 1% at sea level, and 0.4% over the entire atmosphere.”

In other words, we can say that it is a blanket of gases, suspended particles & water vapours. Life is not possible without the atmosphere.

The Earth atmosphere divided into layers vertically on the basis of high & low temperature. These different layers are the troposphere, stratosphere, mesosphere and the thermosphere

  • Troposphere

This is the lower part of the atmosphere; we all are living in it. The troposphere contains approximately 75% of all the air and all water vapours of the atmosphere. All-weather conditions like clouds, rain & snow take place within this layer. The bottom of the troposphere is on the earth surface and the height of troposphere is 10-15 kilometres from sea level. The top of the troposphere varies with latitude; it is highest at equator & lowest at poles. In winters the height of troposphere decreases & increases in summers. The topmost part/layer of the troposphere is known as tropopause or thermal layer or cold trap because at this region the temperature reaches a minimum. The Tropopause plays a very vital role to retain water on earth; it is a barrier which stops the upward movement of rising water vapours. At this point the water vapour converted into ice and gets trapped due to this it is also known as a cold trap.

  • Stratosphere

It is a layer above the troposphere just beyond the tropopause and 35 kilometres deep. The stratosphere spreads from about 15 to 50 km above the Earth’s surface. The temperature of stratosphere rises with height, at the bottom the temperature is less and maximum on top.

The lower portion of the stratosphere has a nearly constant temperature with height but in the upper portion, the temperature increases with altitude because of the absorption of sunlight by ozone.

The stratosphere plays a very important role for life on earth because it contains a layer of ozone which forms a protective shield and protects us from harmful ultraviolet radiation emitting from the Sun.  But sad news, this ozone layer is depleting day by day and is getting thinner due to CFCs (chlorofluorocarbons) effect.

  • Mesosphere

It is a layer between stratospheres and thermosphere; it starts above 50 kilometres and goes up to 8 kilometres.  As we go higher in mesosphere the temperature decreases accordingly. The top of the mesosphere is the coldest part of the Earth atmosphere.

  • Thermosphere

It extends from 80 km above the Earth’s surface to outer space. The temperature is hot and maybe as high as thousands of degrees as the few molecules that are present in the thermosphere receive extraordinary large amounts of energy from the Sun. However, the thermosphere would actually feel very cold to us because of the probability that these few molecules will hit our skin and transfer enough energy to cause appreciable heat is extremely low.

The thermosphere corresponds to the heterosphere, a zone where there is no uniform distribution of gases. In other words, the gases are not well-mixed; instead, they are stratified that is layered, in accordance to their molecular masses. In contrast, the gases in the homosphere (consisting of the troposphere, stratosphere and mesosphere) are uniformly distributed.

       2. Hydrosphere

The total amount of water present on earth is known as hydrosphere. It may be liquid, solid (Ice) or gaseous form (water vapours). Our planet has 71% of water, the ocean holds the maximum share of about 96.5 % of the total. Other water exists in rivers, lakes, ponds & glaciers on the surface of the earth. Water also exists in the atmosphere in vapour form and found in aquifers. Though our planet has a huge quantity of water the drinkable share is very less.

       3. Lithosphere

It is the outer boundary layer or the solid outer part of the earth. It contains the mental, core and an outer crust. In general, the earth crust is composed of three major classes of rocks these are igneous rocks, sedimentary rock and metamorphous rocks. The crusts are classified into two types- the continental crust which is composed of granitic rocks in silicon and aluminium and with a mean density of 2.8, the other is the oceanic crust which is basaltic in composition, consisting more basic minerals and has a mean density of 3.0. the overall average density of earth is 5.5 gm/cc. The lithosphere is categorized in Oceanic Lithosphere and Continental Lithosphere.

The lithosphere consists 15 types of tectonic plates; these are North American, the Caribbean, South American, Scotia, Antarctic, Eurasian, Arabian, African, Indian, Philippine, Australian, Pacific, Juan de Fuca, Cocos, and Nazca.

The continental lithosphere area consists of 30% of the total area of the earth and the rest is oceanic lithosphere. In the continental regions it has a thickness of 35-50 km’s and under the ocean beds; the thickness gets reduced to 6-12 km. The lithosphere is vitally important because it provides the place for life (flora & Fauna). All living organisms inhabit and live upon it. It is also one and only source of natural resources like metals (iron, aluminium & copper) and fuels like petroleum & coal. The movement of the tectonic plates gives rise to mountains & earthquake; it is helpful to form new habitats.

       4. Biosphere

The Biosphere is the zones of earth atmosphere where life exists. The biosphere extends from terrestrial to oceans and from oceans to the high sky where the birds fly. The biosphere is a composition of living organisms (biota) and the abiotic (non-living) factors from which they derive energy and nutrients.

What is Environmental Pollution?

Now a day the environment pollution is one of the biggest issues. It has global impact; all countries are suffering from it. The impact of environmental pollution is increasing day by day and the worst is going to happen in coming days. In a healthy environment, all things are found in balanced form means there is a balance between the biotic & abiotic components of the environment. If we disturb any of the components of the environment then it likely has a harmful effect.

Any change in the characteristics of the environment which contributes to its deterioration is called environmental pollution. In other words, any change in physical, chemical and biological characteristics of our physical environment (Air, Water & Soil) is also known environmental pollution.

The substances which are responsible for pollution are the pollutants. The substances present in the environment in harmful concentration which have an adverse effect on the environment are known as pollutants. These pollutants come from industries, automobile exhausts, burning of fossil fuels, domestic sewage etc.

Types of Environmental pollutants:

Depending upon the existence, the Pollutants are classified into two forms, namely quantitative & qualitative pollutants.                                                            

Quantitative Environmental Pollutants

These are those substances which normally present in the environment but known as pollutants when their concentration (quantity) gets increased due to the mindless activities of human. For example, Carbon di Oxide, present in the environment in normal concentration but when its concentration gets increased than normal due to automobile exhaust & industrial activities which causes adverse effect on human, animals & plants, then it is a qualitative pollutant.

Qualitative Environmental pollutants

The substances which do not normally occur in the environment but are added by human activities. Example, insecticides and pesticides.

Depending upon the form in which they persist after released into the environment, the pollutants are categorized into two forms. These are primary & secondary pollutants.

Primary Pollutants

These are the substances which are emitted directly from source to environment and persist in the same form in which they were added. Example, ash, dust, nitric oxide, sulphur dioxide, hydrocarbon etc.

Secondary Pollutants

These pollutants are not emitted directly from a source; these are those substances which are formed from primary pollutants after interaction with some constituents present in the atmosphere. Sulphur dioxide, nitrogen dioxide, aldehydes, ketones, ozone etc. are the examples.

Nitrogen oxides and hydrocarbons are the primary pollutants released from automobile exhaust but in the presence of sunlight, they react and form PAN (peroxy acyl nitrate) and ozone. PAN & ozone both are the secondary pollutants and both are more toxic than the primary pollutants.

HC + O2 +NO2 + UV           Ozone+aldehydes+PAN+Oxidation Products

According to the nature of disposal, the pollutants are also classified into two forms-

Bio-degradable Pollutants:

These are the pollutants which are rapidly degraded by nature. Domestic sewage and organic pollutants are considered in this category because these are digested by the microbes.

 Non-biodegradable Pollutants:

These are those pollutants which are not degraded by natural means or the degradation processes of these pollutants are very slow in comparison to degradable pollutants. These are mainly inorganic substance, long-chain phenolic chemicals etc.

Types of Environmental Pollution: