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Friday, February 18, 2011

Roles of Bio-Geo-chemical cycles in controlling Environmental Phenomena

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Some of big environmental problems like Climate Change, Acid Rain, and dead zones in coastal areas demand greater attention of the world community. But, these problems can not be addressed without attending to Bio-geo-chemical Cycles.

The earth contains a number of minerals that are essential for sprouting and developing life on the earth. These minerals are found in the soil in forms of different compounds that may be called as Geo-Chemicals. Roots of plants absorb geo-chemicals and green parts of plants convert them into different forms that may be called as biochemicals. This conversion takes place inside a closed system.

The entire green portion of a plant contains numerous organelles in their cells called Chloroplasts, and chloroplasts help in the synthesis of food by absorbing energy from the sun. Now, bio-chemicals join food cycles as plants are eaten up by herbivores and herbivores I turn are eaten up by carnivores. Thus biochemicals flow in the closed system and are recycled instead of being lost. In bodies of organisms these biochemicals are oxidized to give off carbon dioxide which is released into the atmosphere and is in turn used up by plants in the food-making process called as Photosynthesis.

Image 1:  Cells containing Chloroplasts
Most of the biochemicals join the earth by decomposition of living beings after their deaths and decay by decomposers like numerous fungi, bacteria, nematodes and insects. The energy trapped inside their bodies is librated during their decomposition to join the atmosphere. This flow of energy occurs in open system.

Image 2 : A number of Saprophytic fungi act as decomposers 
In some cases, it is possible for an ecosystem to obtain energy without sunlight. Carbon must be combined with hydrogen and oxygen in order to be utilized as an energy source, and this process depends on sunlight. Ecosystems in the deep sea, where no sunlight can penetrate, use sulfur. Hydrogen Sulphide near Hydrothermal vents can be utilized by organisms such as the giant tube worm. 

 Image 3 : Ecosystems in the deep sea ( credit: TopNews.in)

Here Sulphur cycle runs on and in this cycle sulfur can be forever recycled as a source of energy. Here energy can be released through the oxidation and reduction of sulfur compounds. 

Although the Earth constantly receives energy from the sun, its chemical composition is essentially fixed, as additional matter is only occasionally added by meteorites. Because this chemical composition is not replenished like energy, all processes that depend on these chemicals must be recycled. These cycles include both the living biosphere, and the nonliving lithosphere, atmosphere, and hydrosphere. Like sulphur cycle mentioned here, numerous other cycles run on in an ecosystem and some of these cycles are water cycle or hydrologic cycle, carbon cycle, oxygen cycle, nitrogen cycle, phosphorus cycle etc.

Now, the biochemicals that join the earth are changed variously to become geochemical. Thus the cycle of geo-chemicals and bio-chemicals that may together be called as bio-geo-chemical cycle, goes on and on until it is interrupted through human activities. And it is this interruption of various bio-geo-chemical cycles that causes different problems in the natural environment – may they remain big or small. Over use of natural substances, their wastage and various pollutions, and also the habitat destruction are some human activities that cause interruption in bio-go-chemical cycles, imbalance in environment that lead to several environmental problems- both local and global. Hence, it is observed that natural bio-geo-chemical cycles must be maintained in order to avert or minimize environmental problems.
Key Words : bio-geo-chemical cycle, decomposers, deep sea, giant tube worm, environmental problems

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