What is entrophication? What are its effects
living organisms?
Answers
Answer:
“Eutrophication is an enrichment of water by nutrient salts that causes structural changes to the ecosystem such as: increased production of algae and aquatic plants, depletion of fish species, general deterioration of water quality and other effects that reduce and preclude use”.
"Eutrophication is an enrichment of water by nutrient salts that causes structural changes to the ecosystem such as: increased production of algae and aquatic plants, depletion of fish species, general deterioration of water quality and other effects that reduce and preclude use”.
➡This is one of the first definitions given to the eutrophic process by the OECD (Organization for Economic Cooperation and Development) in the 70s.
➡Eutrophication is a serious environmental problem since it results in a deterioration of water quality and is one of the major impediments to achieving the quality objectives established by the Water Framework Directive (2000/60/EC) at the European level. According to the Survey of the State of the World’s Lakes, a project promoted by the International Lake Environment Committee, eutrophication affects 54% of Asian lakes, 53% of those in Europe, 48% of those in North America, 41% of those in South America and 28% of those in Africa (www.lescienze.it).
All water bodies are subject to a natural and slow eutrophication process, which in recent decades has undergone a very rapid progression due to the presence of man and his activities (so called cultural eutrophication).
These structural changes mainly depend on 3 factors:
Use of fertilisers:
Agricultural practices and the use of fertilisers in the soil contribute to the accumulation of nutrients. When these nutrients reach high concentration levels and the ground is no longer able to assimilate them, they are carried by rain into rivers and groundwater that flow into lakes or seas.
Discharge of waste water into water bodies:
In various parts of the world, and particularly in developing countries, waste water is discharged directly into water bodies such as rivers, lakes and seas. The result of this is the release of a high quantity of nutrients which stimulates the disproportionate growth of algae. In industrialised countries, on the other hand, waste water can be illegally discharged directly into water bodies. When instead water is treated by means of water treatment plants before discharge into the environment, the treatments applied are not always such as to reduce the organic load, with the consequent accumulation of nutrients in the ecosystem.
Reduction of self purification capacity:
Over the years, lakes accumulate large quantities of solid material transported by the water (sediments). These sediments are such as to able to absorb large amounts of nutrients and pollutants. Consequently, the accumulation of sediments starts to fill the basin and, increasing the interactions between water and sediment, the resuspension of nutrients present at the bottom of the basin is facilitated (N. Sechi, 1986). This phenomenon could in fact lead to a further deterioration of water quality, accentuating the processes connected with eutrophication (V. Tonolli, 2001).