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Reply in Rajyasabha on Ganga water quality
Why is in news?
- The water quality of the Ganga in 2018 has “improved over last year”, according to a written statement in the Rajya Sabha.
- “Dissolved oxygen” levels had improved at 39 locations and “biological oxygen demand” (BOD) levels and faecal coliform had decreased at 42 and 47 locations respectively.
- These three parameters are a proxy for both the presence of aquatic life as well as microbes that may be harmful to these biota, and are conventionally used to assess the quality of the river.
Biological Oxygen Demand
- Biochemical Oxygen Demand or, is a measurement of the amount of dissolved oxygen (DO) that is used by aerobic microorganisms when decomposing organic matter in water.
What is Dissolved Oxygen ?
- Dissolved Oxygen is the amount of gaseous oxygen (O2) dissolved in the water.
- Oxygen enters the water by direct absorption from the atmosphere, by rapid movement, or as a waste product of plant photosynthesis.
- Water temperature and the volume of moving water can affect dissolved oxygen levels. Oxygen dissolves easier in cooler water than warmer water.
- Adequate dissolved oxygen is important for good water quality and necessary to all forms of life.
- Dissolved oxygen levels that drop below 5.0 mg/L cause stress to aquatic life.
- Lower concentrations cause greater stress .
- Oxygen levels that go below 1-2 mg/L for a few hours may result in large fish kills.
Source
The Hindu