Biochemical oxygen demand (BOD) in a river water:
Correct answer: C. Increases when sewage gets mixed with river water.
- A. Has no relationship with concentration of oxygen in the water.
- B. Gives a measure of Salmonella in the water.
- C. Increases when sewage gets mixed with river water.
- D. Remains unchanged when algal bloom occurs.
Explanation
Biochemical oxygen demand (BOD) is the amount of oxygen taken up by microorganisms that decompose organic waste matter in water. It is therefore used as a measure of the amount of certain types of organic pollutant in water. Biochemical Oxygen Demand (BOD) typically increases when sewage gets mixed with river water. BOD is a measure of the amount of dissolved oxygen that microorganisms need to decompose organic matter in water. When sewage, which contains organic materials, is discharged into a river, it introduces a significant amount of organic matter into the water.
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Ecosystems include biotic and abiotic components, food chains and webs, energy flow, nutrient cycles, populations and ecological relationships. Pollution and conservation cover air, water, soil and noise pollution, their effects on organisms, biodiversity loss, protected areas, sustainable resource use and methods for reducing environmental damage.
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