Eutrophication: a threat to freshwater reservoirs and human health

Abstract

Eutrophication is an environmental problem that results from the increment of chemical nutrients (Phosphorous and Nitrogen) in a water body, transforming from oligotrophic into eutrophic, and in worst cases a hypertrophic stage. This process can occur naturally or due to human action. When the occurrence is natural, this phenomenon occurs slowly due to increase of organic matter by natural runoff from the soil and rock sediments. The anthropic actions generate punctual and diffuse pollution, this phenomenon favor aggravation of eutrophication process. The increment chemical induces a quickly increase of primary production of photosynthetic organisms in the aquatic systems, like phytoplankton and cyanobacteria, decreasing the light availability by increase of organic matter and consequently depletion of oxygen, resulting in loss of biodiversity. Eutrophication causes loss of water quality that is essential for human survival and development of social and economic activities. The eutrophic reservoirs usually present toxins, undesirable taste and odor, and DBPs formation in drinking water, the purification of the contaminated water might be complex and require long-term measures, turning the process quite costly. Therefore, actions to prevent the eutrophication of ecosystems are preferable. Sometimes the restoration of a disturbed environment is necessary, although expensive and complex, for which we present some methods of treatment of some chemical substances.