Which environmental process involves nutrients entering waterways and causing excessive plant and algae growth, leading to oxygen depletion?

• A. Eutrophication
• B. Hydroponics
• C. Variable Rate Technology
• D. Remote Sensing

Answer: (A)

Eutrophication is the process by which excess nutrients, such as nitrogen and phosphorus from fertilizers or sewage, enter waterways. Those nutrients fuel rapid growth of algae and aquatic plants, creating blooms that can cover the water surface or dominate the water column. When these organisms die, bacteria break down the organic matter, using up dissolved oxygen in the water. The result is oxygen depletion (hypoxia or anoxia), which stresses or kills fish and other aquatic life. This chain of events is exactly what the question describes—nutrient input leading to excessive plant and algae growth and subsequent oxygen loss.

Hydroponics involves growing plants in a nutrient-rich solution outside of soil, typically in controlled environments, so it isn’t about nutrient pollution in waterways. Variable Rate Technology and Remote Sensing are management tools for applying inputs or monitoring fields, not natural environmental processes that cause nutrient-driven oxygen depletion in bodies of water.