Digest Scientific Column: Chemistry and the Environment

By: Mohammad Musa

Environmental chemistry is the branch of chemistry which is concerned with the chemical phenomenon occurring in the environment. It can also be defined as the Chemistry that involves the study of the effects that chemicals have on air, water and soil and how they impact the environment and human health. 

To define the environment, we can say it is the sum total of all the living and non-living elements and their effects that influence human life.

The four (4) domain of the Environment

– Atmosphere : Atmosphere is the gaseous mixture of air that surrounds the earth. Its different layers are:

1. Troposphere: It is the lowest region of the atmosphere extending from earth’s surface to the lower boundary of the stratosphere. It contains water vapors and is greatly affected by air pollution.

Ii. Stratosphere:  The layer of the earth’s atmosphere above the troposphere and below the mesosphere, where the Ozone layer is  present in this region.

III. Mesosphere: It is the region of the earth’s atmosphere above the stratosphere and below the thermosphere. It is the coldest region with  temperature – 2 to 92°C of atmosphere.

1. Thermosphere: This is the  upper region of the atmosphere above the mesosphere,  It is the hottest region with temperature up to 1200°C.
2. Exosphere: It is the uppermost region of the atmosphere. It contains atomic and ionic O2, H2 and He(Helium).

– Hydrosphere: It is the aqueous part of the earth e.g. oceans. lakes etc.

– Lithosphere: This is the solid rocky portion of the earth.

– Biosphere: This is the part of the earth which supports  life e.g. animal, human beings.

GreenHouse Effect and Global Warming.

 GreenHouse effect is the phenomenon in which the  atmosphere of earth traps the heat coming out  from the sun and prevents it from escaping into outer space. Certain glasses, called greenhouse gasses [carbon dioxide, methane, ozone, chlorofluorocarbon compounds (CFCs) and water vapor] in the atmosphere absorb the heat given by earth and radiate back to the surface of the earth.The warming of the earth led to the warming of air due to greenhouse gasses which is known as global warming.

Importance of GreenHouse Effect (or Global Warming)

1. The greenhouse gasses are useful in keeping the earth warm with an average temperature of about 15° to 20°C. 
2. Increase in the concentration of CO2 in the atmosphere leads to an increase in the temperature of the earth’s surface. As a result, evaporation of surface water will increase which further helps in the rise of temperature and results in the melting of glaciers and polar ice caps and hence, level of sea water may rise.
3. There may be less rainfall in this temperature zone and more rainfall in the dried areas of the world.

The disadvantages of Greenhouse effect

1. Marine life and ecosystem would be destroyed. Oceans absorb carbon dioxide thereby affecting the level of alkalinity. Many forms of marine life would be adversely affected if alkalinity increases. Polar ecosystems would be destroyed. 
2. Global warming would also affect the weather pattern. Rainfall would become erratic in many parts of the world. This might eventually lead to desertification. 
3. Water level balance of the earth would be destroyed. Polar ice caps would melt leading to an increase in the ocean level. Floods will inundate low lying areas.