Eutrophication, the over-enrichment of nutrients in water bodies, can be deadly to the ecosystem
What is Eutrophication?
Eutrophication is a process caused by the gradual increase in the concentration of phosphorus, nitrogen and other plant nutrients in the biosystem, which are introduced into the ecosystem primarily when streams wash away soils from land. Debris, products of reproduction and dead terrestrial organisms are then deposited in water bodies as they enter the ecosystem. The overabundance of nutrients in water bodies results in harmful environmental effects. As the organic materials break down into nutrients, the productivity or fertility in the ecosystem increases. A great concentration of algae and microscopic organisms in the water bodies feed on the nutrients, growing, propagating and forming unsightly algae blooms on the water surface. When the scum on the water's surface blocks light penetration, plants produce less oxygen for underwater life. Moreover, dead algae are decomposed by bacteria and produce putrid odors or even release toxins in the water. The bacteria will consume oxygen in the water during the decomposition process and deplete the oxygen needed to sustain life. Ultimately, without oxygen, bodies of water become "dead zones."
A Global Issue
Given the widespread extent of water quality degradation caused by nutrient enrichment, eutrophication has been and continues to be a major global challenge. A study by the United Nations Environment Programme indicates that 30~40% of lakes and reservoirs around the world have been affected by eutrophication. It poses a serious threat to the aquatic ecosystem, yet current solutions are either ineffective or extremely costly. Tainted drinking water supplies and the degradation of recreational opportunities, for example, can be detrimental to human health and well-being. Eutrophication also contributes to the spread of gastrointestinal and dermatological diseases such as conjunctivitis and hypoxia. In the United States alone, the combined costs of the treatments for eutrophication in freshwaters are approximately $2.2 billion annually.
Current Solutions
According to Natural Resources 235, the best way to cope with eutrophication is to regulate the amount of fertilizers used for agriculture, one of the major reasons behind eutrophication. However, there are already a lot of dead zones, which are bodies of water that are hypoxic. Therefore, taking preventative measures would not be the ideal way to cope with the current condition. Governments around the world have been implementing two main methods – multi-soil layering (MSL) and biomanipulation. Neither, however, is ideal. MSL is costly, and biomanipulation lacks stability. There is a possibility of engineering E. coli cells to decline the external phosphorus level. Cost efficiency and longevity must be taken into account when such solutions are being developed.