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Environmental Chemistry — Chemistry STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceChemistryEnvironmental Chemistry3 Marks
Question
What are the sources of dissolved oxygen in water?
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Answer

Oxygen reaches water either through atmosphere or from the process of photosynthesis carried out by many aquatic green plants during day light. However, during night, photosynthesis stops but the plants continue to respire, resulting in reduction of dissolved oxygen. The dissolved oxygen is also used by microorganisms to oxidize organic matter.
In brief, sources of dissolved oxygen in water are:
  1. Photosynthesis by aquatic plants.
  2. Due to the direct contact of water surface with air.
  3. Mechanical aeriation.

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