Ületoituvus

Ületoituvus, also known as eutrophication, is a process where a body of water becomes excessively enriched with nutrients, primarily phosphorus and nitrogen. This nutrient enrichment often leads to an overgrowth of algae and aquatic plants, a phenomenon called an algal bloom.

When these blooms die, their decomposition by bacteria consumes large amounts of dissolved oxygen in the water. This depletion of oxygen, termed hypoxia or anoxia, can create dead zones where fish and other aquatic organisms cannot survive. The primary sources of excess nutrients are often agricultural runoff containing fertilizers and animal waste, as well as untreated sewage and industrial discharges.

While natural eutrophication occurs over long geological timescales, human activities have significantly accelerated this process in many lakes, rivers, and coastal waters. This human-induced form is often referred to as cultural eutrophication. The consequences of eutrophication extend beyond oxygen depletion, impacting biodiversity, water quality for drinking and recreation, and the overall health of aquatic ecosystems. Mitigation strategies focus on reducing nutrient inputs from human sources through improved wastewater treatment, responsible agricultural practices, and control of urban runoff.