EUTROPHICATION

When water bodies such as lakes, estuaries and slow moving streams receive excess nutrients ,it results in excessive plant (algal) growth . This process is called eutrophication.

This excessive growth of plants such as 

Water hyacinth and algae reduces the dissolved oxygen (BOD- biological oxygen demand) in water. The water body then becomes incapable of supporting fishes and  other forms of aquatic life. Excessive growth of algae in such water bodies is described as algal bloom.

Nitrates and phosphates are the two main substances(nutrients) that causes such condition, which is a direct result of pollution. These nutrients come from a variety of sources,such as fertilizers applied to agricultural fields and golf courses, excessive use if detergents, erosion of soil containing nutrients,untreated sewage and discharges from sewage treatment plants.

EUTROPHICATION not only leads to reduced oxygen but also produce foul odour and slow death of water body. Thus, biodiversity in these aquatic ecosystems is often disturbed and depleted.

Algae blooms are often toxic and can result in the deaths of water fowl, fish, and other small animals. Additionally, it can make humans very sick. When the algae dies, the decomposition process absorbs oxygen out of the water column, resulting in a state of anoxia. In severe cases, fish can suffocate in the oxygen-devoid water, and a dead-zone is created. Once a lake becomes "dead" there is no bringing it back. There are over 400 dead-zones worldwide.

Because you cannot restore a dead-zone, the best method for treating eutrophication is to prevent it in the first place. The good news is, there are several ways that this can be done. We'll start with the simpler solutions and progress to the more complex ones.

The Gulf of Mexico is one of the largest dead-zones on the planet. This is the result of decades of excess nutrients flowing down the Mississippi River and dumping into the estuary.

The most politically plausible option is restoring riparian zones. A riparian zone is a strip of land adjacent to a water body that is covered in foliage. The riparian zone acts as a buffer between the water body and the excess nutrients. Before the nutrients can reach the water, they are absorbed and filtered by shrubs and grasses that protect the waterline. Many riparian zones have been destroyed due to erosion or construction of waterfront property.

This is an excellent solution because it is relatively inexpensive, creates jobs, and restores natural habitats.

Our next solution is relatively simple, although it may have political ramifications.

Using less fertilizer is an extremely simple and effective way to halt eutrophication in it's tracks. 68% of nutrients occur as a result of over fertilization (EPA). Essentially, farmers are using more fertilizer than their crops can utilize. A scoop of fertilizer will help a plant grow just as much as a truckload. In either option, the plant has reached its growing capacity. The difference is, one creates unnecessary waste.

This last solution for eutrophication is the most expensive and controversial, yet the most effective. Picture a bubbler inside of a fish tank. The bubbler cycles oxygen through the system, while simultaneously stirring up the water so that algae cannot form. This can be done on a large industrial level. There are options to place the bubbler under water like the fish tank, or they can be placed above water like a fountain. This is the most effective option because it physically stops dead-zones by restoring oxygen into the system.

Riverstone Park in Coeur d' Alene, Idaho features an above ground fountain/bubbler. This man-made lake is shallow and stagnant, a perfect place for algae populations. The water fountain prevents this from happening by stirring up the water and cycling oxygen back into the water column.

There are obvious downsides for this option. It is expensive not only to install, but to maintain. Additionally, some may argue that a fountain is gimmicky or takes away from the natural beauty of a water body. Others may argue that a fountain is more ideal than a green cesspool.