rehevöitymisestä

Rehevöityminen, often translated as eutrophication, refers to the process by which a body of water becomes overly enriched with minerals and nutrients. While natural eutrophication is a slow aging process, human activities have significantly accelerated it. The primary culprits are agricultural runoff, containing fertilizers rich in phosphorus and nitrogen, and discharge from sewage and industrial wastewater.

This excess of nutrients fuels the rapid growth of algae and aquatic plants, a phenomenon known as algal blooms. When these blooms die, they sink to the bottom and are decomposed by bacteria. This decomposition process consumes large amounts of dissolved oxygen in the water, leading to hypoxia or anoxia, conditions where oxygen levels are dangerously low.

The consequences of eutrophication are severe. Low oxygen levels can suffocate fish and other aquatic organisms, leading to large-scale die-offs. The dense algal blooms can block sunlight from reaching submerged aquatic vegetation, hindering its growth and disrupting the entire ecosystem. Furthermore, some algal blooms, particularly those of cyanobacteria (blue-green algae), can produce toxins harmful to both aquatic life and humans. Addressing eutrophication typically involves reducing nutrient inputs from human sources through improved wastewater treatment, sustainable agricultural practices, and land-use management.