What does the term "eutrophication" refer to?

The term "eutrophication" refers specifically to the excessive growth of algae in water bodies caused by an overload of nutrients, mainly nitrogen and phosphorus. This process often occurs due to agricultural runoff, wastewater discharges, or other human activities that introduce these nutrients into aquatic systems.

Eutrophication can lead to harmful algal blooms that can deplete oxygen in the water, leading to dead zones where aquatic life cannot survive. It disrupts ecosystems, affects water quality, and can create health hazards for humans and wildlife. Understanding this concept is essential for environmental management and wastewater treatment practices, as it highlights the importance of controlling nutrient inputs into water bodies to maintain ecological balance.

The other options listed do not capture the essence of eutrophication, which specifically centers around nutrient-induced algal growth rather than physical treatment processes or energy recovery.