Which statement about nitrates and phosphates in water quality is correct?

Which statement about nitrates and phosphates in water quality is correct?

• A. Nitrates and phosphates are not harmful to aquatic ecosystems.
• B. Phosphates cause eutrophication; nitrates do not.
• C. Nitrates and phosphates both can promote algal blooms and deoxygenation in water bodies.
• D. Only phosphates cause eutrophication, nitrates do not.

Answer: (C)

Nitrates and phosphates are essential nutrients for algae and aquatic plants. When their concentrations are elevated, they remove nutrient limitations and fuel rapid growth, leading to algal blooms. The accumulation and subsequent decay of these blooms consume a lot of dissolved oxygen, which can deplete oxygen levels in the water and create dead zones that stress or kill fish and other aquatic life. Because both nutrients can drive this sequence—boom in growth followed by oxygen depletion—the statement that nitrates and phosphates both can promote algal blooms and deoxygenation captures the real impact of nutrient pollution on water quality. Choices that claim these nutrients are harmless, or that only one of them drives eutrophication, don’t fit real-world dynamics. In practice, managing either nutrient helps protect aquatic ecosystems from eutrophication and its harmful effects.

Nitrates and phosphates are essential nutrients for algae and aquatic plants. When their concentrations are elevated, they remove nutrient limitations and fuel rapid growth, leading to algal blooms. The accumulation and subsequent decay of these blooms consume a lot of dissolved oxygen, which can deplete oxygen levels in the water and create dead zones that stress or kill fish and other aquatic life. Because both nutrients can drive this sequence—boom in growth followed by oxygen depletion—the statement that nitrates and phosphates both can promote algal blooms and deoxygenation captures the real impact of nutrient pollution on water quality.

Choices that claim these nutrients are harmless, or that only one of them drives eutrophication, don’t fit real-world dynamics. In practice, managing either nutrient helps protect aquatic ecosystems from eutrophication and its harmful effects.