An excess runoff of which fertiliser nutrients most commonly drives eutrophication and algal blooms in lakes and rivers?
- ((a))
Potassium salts and urea (nitrogenous)
- ((b))
Sodium salts and potassium salts
- ((c))
Phosphate compounds and nitrate compounds
- ((d))
Zinc salts and nitrate compounds
Show Answer
Phosphate compounds and nitrate compounds
The correct answer is Phosphate compounds and nitrate compounds.

Key Points
- Phosphate compounds and nitrate compounds are the primary nutrients responsible for eutrophication and the proliferation of algal blooms in aquatic ecosystems.
- When these nutrients are present in excess, they stimulate the growth of algae and aquatic plants, leading to a dense algal bloom that depletes oxygen levels in the water.
- This process, known as eutrophication, causes hypoxic (low oxygen) or anoxic (no oxygen) conditions, which can lead to the death of aquatic life, including fish and other organisms.
- Sources of these nutrients include agricultural runoff, untreated sewage, and industrial effluents, which introduce large amounts of fertilizers into water bodies.
- Efforts to mitigate eutrophication include improving wastewater treatment, regulating agricultural practices, and minimizing the use of phosphate-based detergents.

Additional Information
- Potassium salts, such as potassium chloride, are essential for plant growth but are not directly linked to eutrophication or algal blooms.
- Urea is a nitrogenous fertilizer, but its contribution to eutrophication is less significant compared to phosphates and nitrates because urea breaks down and releases nitrogen more slowly.
- Potassium primarily aids in water regulation and enzyme activity in plants rather than causing nutrient overloading in water bodies.
- Zinc salts are essential micronutrients for plant and animal growth but are not directly linked to eutrophication.
- Eutrophication
- Eutrophication is primarily caused by nutrient enrichment, especially with nitrogen and phosphorus, in aquatic ecosystems.
- It results in overgrowth of algae, oxygen depletion, and biodiversity loss.
- Effective management strategies include reducing nutrient inputs, promoting sustainable farming practices, and enhancing water treatment facilities.