Читать книгу Encyclopedia of Renewable Energy - James Speight G., James G. Speight - Страница 74

Algal blooms refer to the rampant growth of certain microalgae, which in turn leads to the production of toxins, disruption of the natural aquatic ecosystems, and increases the costs of water treatments. The blooms take on the colors of the algae contained within them. Graham states that the main toxin producers in oceans are certain dinoflagellates and diatoms. In freshwaters, cyanobacteria are the main toxin producers, though some eukaryotic algae also cause problems. Under natural conditions, Graham notes that algae use the toxins to protect themselves from being eaten by small animals and only need a small amount to protect themselves.

The main cause of algal blooms is nutrient pollution in which there is an excess of nitrogen and phosphorus, which can push algae toward unrestrained growth. The phenomenon is caused by a variety of human activities in which the fertilizers used in agriculture and animal manures are rich in nitrogen, while improperly treated wastewater is high in both nitrogen and phosphorus.