What does eutrophication refer to?
Last updated Jun 24, 2026
Correct Answer:
Option A —
Natural aging of a lake by nutrient enrichment of its water
Understanding EutrophicationEutrophication is a biological process that occurs when a body of water becomes overly enriched with minerals and nutrients (primarily phosphates and nitrates).
The Process: While eutrophication can happen naturally over centuries as a lake fills with sediment and organic matter, human activity often accelerates it—a process called "cultural eutrophication"—through fertilizer runoff or sewage discharge.
The Chain Reaction:
Nutrient Loading: High levels of nitrogen and phosphorus enter the water.
Algal Bloom: This "food" causes a rapid increase in algae and phytoplankton growth on the surface.
Oxygen Depletion: When the algae die, bacteria decompose them. This decomposition consumes the dissolved oxygen in the water.
Dead Zones: Lack of oxygen leads to the death of fish and other aquatic organisms, effectively "aging" the lake and turning it into a marsh or land over time.
Analysis of Other Options
B) Nutrient deficit: This would be the opposite of eutrophication (oligotrophic conditions).
C) & D) Expansion/Increasing depth: Eutrophication actually leads to the shallowing of a lake because the accumulation of dead organic matter and silt on the bottom gradually reduces the lake's depth.
Answer verified by Quintessence Classes faculty — Karan Nagar, Srinagar.
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