Q3 of 55 Page 117

Is it true that if the dissolved oxygen level drops to zero, the water will become septic. Give an example which could lower the dissolved oxygen content of an aquatic body.

When the dissolved oxygen level drops to zero, many aquatic animals die because they don’t get any dissolved oxygen to breathe. This results in water becoming septic.


Organic pollution (increased growth of nitrogen and phosphates leads to increased growth of algae and plants and when these plants and algae die, they become organic matter) is an example which causes lowered dissolved oxygen content of an aquatic body.


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