Eutrophication: Prevention Methods

    Having thought about the consequences of eutrophication, we might now think 'do methods exist to prevent this?' Now the best way to reduce this nutrient-load on water bodies would be to stop having agricultural areas and settlements near them - obviously this is completely unfeasible and never going to happen. However there are several measures that can be put in place to maintain the health of our water bodies, without severely impacting our way of life:

• Riparian Buffers: These are vegetated areas between a river and adjacent areas of land use, and are a widely used method for removing pollutants (like the excess nutrients in eutrophication) from agricultural areas. This means less surface run-off meets a stream/river, leading to less nutrients being deposited at their mouth (e.g. in a lake or sea), and some prevention of eutrophication. Lee, Isenhart and Schultz (2003) found a combined species buffer zone can remove between 80-97% of the nitrogen and phosphorous run-off. However different species have been found to contribute different rates of absorption to a buffer zone (Haycock and Pinay, 1993). Older forests have also been shown to be much less efficient at trapping N and P than younger forests (Mander et al., 1997).

A Riparian Buffer zone either side of a stream in Iowa.

• Maintenance of river floodplains: Maintaining flat plains adjacent to rivers can also help to reduce nutrient-load in mouth water bodies; as when the river breaks its banks and floods, sediments and nutrients are deposited on the plains either side of the river. Tockner et al., 2002, found of a river-floodplain system in Switzerland that the floodplain served as a major sink of phosphorus and suspended matter, and was never a source for organic nutrients. However quantification of their use in preventing eutrophication does vary; Tockner et al., 1999, found of a system in Austria that the floodplain did serve as a sink for sediments and nitrates, but was actually a source for dissolved organic carbon and algal biomass.

A river floodplain on the Isle of Wight.

• Meandering: Having a wide and straight river causes the water to flow faster, preventing sediments and nutrients from being deposited on the banks and bottom, and reaching larger water bodies as nutrient-rich. Introducing meanders to rivers slows the water flow, and causes more nutrients to be deposited on the bends; reducing eutrophication in end water bodies.

Meanders of the Rio Cauto in Cuba.

• Divertion of waste pipes: A fairly obvious measure, sewage pipes that offload into water bodies should be diverted away from areas in danger of eutrophication. Alternatively, wastewater can be treated to reduce the amount of nutrients carried into water bodies. This can dramatically decrease incidences of eutrophication, as anthropogenic waste is one of the widest known causes for destruction of lake ecosystems (Sreenivasan, 1969).

   These are all ways in which we can fairly easily reduce anthropogenic pollution and associated eutrophication of water bodies. While methods such as re-meandering and creation of floodplains may have high monetary costs and require maintenance, these are still preferable to the difficult, time-consuming, and often impossible process of recovering systems damaged by unnatural eutrophication.