Eutrophication

 

Introduction

As the world population is increasing rapidly, food security and hygiene are becoming some of the rising problems, especially in developing countries.To be able to supply a magnitude of food, farmers have to come up with many methods to increase the yield of crops, including the use of fertilizers, herbicides, insecticides and many agricultural machinery. Sustaining such a big population also requires proper care for their living conditions and hygiene, but untreated sewage is a serious yet neglected problem in many countries. , which leads to many pollutant issues with water eutrophication being one of the most remarkable ones. This essay provides a scientific analysis of the causes of the situation and discusses my personal perspective on this issue.

Causes

Water eutrophication is a phenomenon caused by the leaching of phosphates and nitrates ions into rivers, streams, etc that damages the ecosystem there and kills the population living in the water. One of the major causes of the problem is the overusing of fertilisers by farmers. With an excessive amount of nutrients from those ions, algae and green plants in the water can grow rapidly and expand throughout the surface, completely covering the upper layer of the water. This is called an algae bloom. The sunlight then can’t penetrate the thick layer of algae, which kills the plants growing beneath them due to the inability to carry out photosynthesis. Even the plants on the top of the water eventually die as well. The dead organisms remain as a great food source for decomposers such as bacteria and enable them to breed in a rapid way and during that process, they carry out aerobic respiration, which uses up the dissolved oxygen in the water. This leads to a lack of oxygen in the environment, leaving low concentration of this gas for other living things . Another reason concerned is untreated sewage discharged directly into streams as it contains waste products such as faeces, urine, detergent and many more and these provide a good food source for numerous kinds of aerobic bacteria. Once again, their population rises, depleting the oxygen level in water.

Real life example

A notable real life example of eutrophication is in the Caspian Sea (the largest lake in the world, located in Asia). “Nitrogen-enriched and phosphorus-enriched compounds are released from household wastewater and resulted from the substantial uses of agricultural fertilisers are transported to the Sea through rivers and drainage system and also get accumulated in the Vogal, Ural and Terek rivers which then end up in the Caspian Sea. Additionally, large concentrations of detergents and ammonium have been previously reported in the north of the Sea. According to the United Nations Environment Program, respectively, about 886 100 and 104 280 tons of total nitrogen and total phosphorus, were annually discharged in the sea from rivers, industries, and municipalities within the Caspian Sea basin.”. The effect of eutrophication can be severe on the fragile biodiversity of the Caspian Sea, which is already harmed by climate change and pollution. Providing 90% of the world’s caviar supply as well as resting regions for tens of millions of migratory birds annually, the consequences are inestimable if the situation exacerbates. 

Solutions

For its various causes, the issue is insoluble with only a single solution and more radical methods and alternatives are required to resolve the problem. Due to the fact that fertilisers increase the yield of crops exponentially, farmers are unwilling to give up on those, for they will have to raise the selling price so that their businesses are lucrative. Organic fertilizers such as manures are potential alternatives as they do not contain many nitrates that can easily be leached out of the soil. Instead, they release the ions gradually, over a long period of time to assure the crops are given time for more efficient absorption. Notwithstanding, the usage of manures can still be adverse whenever the weather is rainy or when crops are unable to consume the nutrients so they accumulate in the ground and get leached into the water. Many actions can be done to limit the harmful effects of eutrophication, for example: avoid applying them near neither streams or rivers nor before rain is forecast and use them in apposite quantities so that plants can take up right away. Moreover, good sewage treatment will play a vital role in eradicating the excess ions as well as water-borne diseases (like cholera, diarrhea, etc). As far as I’m concerned, scientists should come up with more alternatives to those conventional fertiliser based on empirical study to provide a viable solution to the issue. Furthermore, educating farmers about the consequences of eutrophication as well as methods to adjust it will contribute to alleviate the current situation. 

Generally speaking, eutrophication is a detrimental phenomenon that results in the loss of habitats as well as biodiversity in many areas. Current practices are contributing to resolve the problem though further research should be conducted in order to mitigate the severity of the situation. Being able to reach an equilibrium between human needs and ecological preservation is really crucial, especially when the Earth is dying out due to the exploitation of natural resources.

Sources

1. IGCSE Biology coursebook, page 409 & 410
2. Caspian Sea is eutrophying: the alarming message of satellite data” from Anahita Modabberi, Roohollah Noori, Kaveh Madani, Amir Houshang Ehsani, Ali Danandeh Mehr, Farhad Hooshyaripor and Bjørn Kløve