Unit 14 – Environmental Chemistry – summary

Environmental chemistry plays a major role in environment. Chemical species present in the environment are either naturally occurring or generated by human activities.

Environmental pollution is the effect of undesirable changes in the surrounding that have harmful effects on plants, animals and human beings. Pollutants exist in all the three states of matter.

We have discussed only those pollutants, which are due to human activities, and can be controlled. Atmospheric pollution is generally studied as tropospheric and stratospheric pollution.

Troposphere is the lowest region of the atmosphere (~10 km) in which man along with other organisms including plants exist.

Whereas stratosphere extends above troposphere up to 50 km above sea level. Ozone layer is one of the important constituents of stratosphere.

Tropospheric pollution is basically due to various oxides of sulphur, nitrogen, carbon, halogens and also due to particulate pollutants.

The gaseous pollutants come down to the earth in the form of acid rain. 75% of the solar energy reaching earth is absorbed by the earth surface and rest is radiated back to the atmosphere.

These gases mentioned above trap the heat which result into global warming.

It is important to realise that these very gases are also responsible for the life on the earth as they trap the requisite amount of solar energy for the sustainance of life.

The increase in the greenhouse gases is raising the temperature of the earth’s atmosphere which, if not checked, may eventually result in melting of polar ice caps and consequently may submerge the costal land mass.

Many human activities are producing chemicals, which are responsible for the depletion of ozone layer in the stratosphere, leading to the formation of ozone hole.

Through the ozone hole, ultraviolet radiations can penetrate into the earth’s atmosphere causing mutation of genes.

Water is the elixir of life but the same water, if polluted by pathogens, organic wastes, toxic heavy metals, pesticides etc., will turn into poison.

Therefore, one should take care to follow international standards to maintain purity levels of drinking water.

Industrial wastes and excessive use of pesticides, result into pollution of land mass and water bodies.

Judicious use of chemicals required for agricultural practices can lead to sustainable development.

Strategies for controlling environmental pollution can be:

  • waste management i.e., reduction of the waste and proper disposal, also recycling of materials and energy,
  • adopting methods in day-to-day life, which results in the reduction of environmental pollution. The second method is a new branch of chemistry, which is in its infancy known as green chemistry. It utilizes the existing knowledge and practices so as to bring about reduction in the production of pollutants.

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