Agricultural runoff carrying synthetic fertilizers into rivers and lakes causes severe water degradation through eutrophication. Arrange the following stages of eutrophication in the correct sequential order from the initial nutrient influx to the eventual ecological collapse:
- 1Nutrient enrichment of water bodies by nitrate and phosphate runoff
- 2Rapid proliferation and bloom of algae on the water surface
- 3Aerobic bacterial decomposition of dead organic matter consuming dissolved oxygen
- 4Widespread anoxia leading to massive mortality of fish and aquatic organisms
Answer
The correct sequence is: Nutrient enrichment of water bodies by nitrate and phosphate runoff → Rapid proliferation and bloom of algae on the water surface → Aerobic bacterial decomposition of dead organic matter consuming dissolved oxygen → Widespread anoxia leading to massive mortality of fish and aquatic organisms.
Eutrophication begins with the influx of nutrient-rich runoff (nitrates and phosphates). This triggers an explosive growth of algae (algal bloom). When the algae die, aerobic bacteria decompose the organic biomass, depleting the water body's dissolved oxygen. Finally, the resulting oxygen deficiency (anoxia) leads to widespread mortality among aquatic organisms.
Step-by-Step Solution
Key Concept
Eutrophication and aquatic degradation sequence