Question

A lake with an inflow of domestic sewage, rich in organic waste, may result in

• A. Drying of the lake very soon due to algal bloom
• B. An increased production of fish due to lot of nutrients
• C. Death of fish due to lack of oxygen
• D. Increased population of aquatic web organisms

Answer 1

The correct option is C Death of fish due to lack of oxygen

Domestic sewage contains biodegradable organic matter, which is decomposed by bacteria and other micro-organisms. They multiply by using these organic substances as substrates. Micro-organisms involved in biodegradation of organic matter in the water body consume a lot of dissolved oxygen, and as a result, there is a sharp decline in dissolved oxygen. This causes mortality of fish and other aquatic creatures.