What does eutrophication refer to?

Eutrophication is a process primarily caused by an accumulation of nutrients, particularly nitrogen and phosphorus, in aquatic systems, which leads to excessive growth of algae. This rapid algal bloom can deplete oxygen levels in the water and harm aquatic life. It often occurs as a result of nutrient runoff from agricultural lands, urban areas, and wastewater, creating a detrimental cycle that affects water quality and ecosystem health.

The other options represent different environmental issues that do not pertain to eutrophication. For example, excessive soil erosion deals with the loss of topsoil due to wind or water, an increase in soil pH pertains to soil chemistry and nutrient availability, and reduction of sediment in rivers involves sediment transport dynamics rather than nutrient enrichment in waterbodies. The distinction is crucial for understanding the specific impacts of nutrient management and water quality in agricultural practices.