Thursday, August 18, 2011

Earth as a Source of Elements

Earth is a source of a large number of elements. The different parts of earth contains different elements. Earth can be broadly divided into three main parts; namely Atmosphere, Hydrosphere and Lithosphere.
1.         ATMOSPHERE
It consists of a gaseous mixture surrounding the earth. The main constituents of atmosphere are; nitrogen (» 78%), oxygen (» 21%) and other gases such as CO2, He, Ne, Ar, Kr, Xe (less than 1%).
2.         HYDROSPHERE
It covers about 80% of earth’s surface and constitutes streams, lakes, rivers and oceans. There are large number of elements present in sea water. These are present in the form of their dissolved salts.
3.         LITHOSPHERE
It is a solid phase of the earth. It consists of different type of rocks such as igneous rocks, sedimentary rocks and metamorphic rocks. These rocks from a source of large number of elements.
The distribution of main elements on the surface of the earth in terms of their relative abundance is as follows;

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