Eutrophication run-offs containing animal waste from farmlands

EutrophicationIntroduction of eutrophication          Eutrophicationis the immoderate growth of aquatic plant life due to the increase of inorganicions. Plant growth is usually stimulated when the environment is rich withinorganic ions that may come from the accidental pollution by untreated sewage,run-offs containing animal waste from farmlands into lakes, river or pond andleaching of inorganic fertiliser. Apart from human and animals activities,eutrophication can occur through natural process.Causes of eutrophication          Eutrophication is mainlycaused by the immoderate use of inorganic fertiliser. These fertilisersused containing nitrate and phosphate from agricultural land will not all beabsorbed by the crops causing leaching of the fertilisers by rainwater into thesources of water such as rivers, streams, lakes, ponds and oceans. This causesthe increased in the nutrient content in the water.

Ions such as ammonium,nitrate and phosphate can booth the growth of aquatic plants like algae. Duringspring time, the rise in water temperature can also promote the growth of algaeand result in population explosion which is known as algal bloom. ( Figure 1.0shown in Appendices 1 ) they may grow to an extent that the surface of thewater is totally covered by the algae. This will causes the sunlight unable toreach the bottom of the pond.

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The plants in the pond will not receivesufficient sunlight that will result in the decrease of the rate ofphotosynthesis. Thus, aquatic plants will die which leads to the decrease ofthe amount of oxygen in the water. Saprotrophic aerobic bacteria will decomposethe dead plants and the population of bacteria will increase in size.Consequently, the limited oxygen in the water will be used up be the bacteria,causing the water to become deoxygenated and increased in the biochemical oxygendemand, BOD. This will result in the decaying anaerobic and the formation ofhydrogen sulphide. Many of the aquatic plants and marine lives such as fishwill die due to the lacking of oxygen and cannot tolerate hydrogen sulphide.           Eutrophication causes bythe discharged of animal wastes from farmlands into rivers, streams, lakes,ponds and oceans will be the same as the leaching of inorganic fertilisers fromagricultural land.           On the other hand,eutrophication can happen under natural process besides from the activitiescarried out by human or animals.

  (Figure 1.1 shown in Appendices 1 )  Thisnatural process will take a much longer time to occur. In lowland ponds orlakes, the amount of dissolved nutrients will increase steadily. In theopposite, the water of mountain lakes and the streams that are in continuousmotion will have a lower amount of dissolve nutrients. The lowland ponds orlakes will become shallow and shallow due to the washing of sediments from theside of the ponds. In contrast, the side of the streams is usually stony withpoor soil, so the dissolve minerals are little in the water and less or noaquatic life can be seen. The water would be clear and the lake bed can beseen. This condition is called oligotrophic.

( Figure 1.2 shown in Appendices 1) . In the lakes that undergo eutrophication, plants can grown on the littoralareas when the lakes become shallow enough. As this natural process requires along time to happen, it is also known as lake aging. The natural eutrophicationcan be varied due to the climate changes and geology.Biochemical oxygen demand ( BOD )          Biochemical oxygendemand ( BOD ) refers to the amount of oxygen that is utilized when all theorganic matter in one litre of water is oxidized by living organisms in thewater. This is used to measure the level of water pollution. The larger theamount of the organic matter present in the water, the higher the amount of theaerobic saprotrophic bacteria that feed on the organic matter.

The dissolvedoxygen level is low result in high BOD level. This indicates that the waterquality is poor. In contrast, the dissolved oxygen level is high result in lowBOD level. This indicates that the water quality is good. There is anexperiment for BOD. A sample of water is mixed with the methylene blue to knowabout whether the water has been badly polluted or not. When the time taken formethylene blue solution to decolourised increases, the dissolve oxygen level ishigh result in low BOD level.

The amount of the aerobic saprotrophic bacteriathat is present is low and the water have a good quality.Examples of eutrophication          In 1960s, Lake Erie wasknown for its eutrophication when numerous fishes died in a sudden.  ( Figure 1.3 shown in Appendices 1 ) Lake Okeechobee has been eutrophic by blue green algalblooms in 1960 due to the development of agriculture and Run-offs containinganimal waste. ( Figure 1.

4 shown in Appendices 1 ). Eutrophication also occursin India where the pond water in Ranchi City is full of algae. ( Figure 1.5shown in Appendices 1 ) Eutrophication in Gulf of Mexico is so serious and it’sfar taken into consideration as a dead zone and the lifeless region isbelieved to be expanding.  ( Figure 1.6 shown in Appendices 1 )Effect of eutrophication on aquatic plantsand aquatic life          Algal bloom thatcompletely cover the water surface causes the aquatic green plants cannotperform photosynthesis due to the lacking of sunlight. The oxygen in the waterbecome limited and causes the aquatic lives like fishes, prawns, shrimps, crabsand others to die. This can lead to the decrease in the diversity of thespecies in the water.

In the extreme cases, oxygen level continuesto drop and the water become completely deoxygenated. Anaerobic bacteria willgrow and release toxic gases such as hydrogen such as hydrogen sulphide. Thesegases cause the death of the aquatic lives and reduce the production of them.The will consequently affect the world population and causes starvation in somecountries. The economies of the countries that depend on the export of theseafood as their income will be badly affected and the people in the countrieswill also facing a difficult time.

Effect of eutrophication on human health          Drinking water made fromthe water supplies that have undergoes eutrophication can have a harmful effecton our bodies. It will lead to deaths even though a small amount of thatparticular water is drunk. This is because the toxic gases such as hydrogensulphide that are released from the saprotrophic aerobicbacteria are poisonous. It does not only causes the death of fishes but alsohuman. If people are avoiding drinking the water come from the water supplies that have undergoes eutrophication, acertain risk of getting cancer will still be there.

This is because theconcentration of the toxic will accumulate throughout the food chain and at theends, the toxic will still reach to human. For an example, the toxic will bestored in the muscle of shellfishes and when we eat the shellfishes, we stillcan be poisoned. Besides, the blood circulation system in babies will beaffected due to the present of nitrogen in the contaminated drinking water. Effect of eutrophication on recreationalplaces          The eutrophicationprocess causes the recreational places to be decreased. No one will be relaxingby fishing, rowing boats or swimming in ponds or lakes that have undergoeutrophication. Ways to prevent eutrophication          There are numerouseffective ways that one can take to prevent eutrophication.

First of all, thefarmers should reduce the amount of fertilisers that they are use from thegrowth of their crops. They should avoid the use of excessive fertilisers andalso water. This is because water that is in excess will wash the soil thatcontains minerals such as nitrate and phosphate into the nearby rivers, streamsor lakes. They can also practice not using water sprinklers when watering theirplants as the sprinklers can cause large amount of water to be waste besideswashing the nutrients into the water supplies.          Moreover, some schools that are having lakes or ponds must always takecare of the lakes or ponds to prevent eutrophication take place in naturalprocess. The school can prevent this by digging the lakes or ponds annually toprevent the accumulation of the sediments in the ponds or lakes.          Lastly, the government must have stricter laws or a limit for the usageof the fertilisers so that the leaching of the fertilisers containing nitrateor phosphate into the rivers or ponds can be reduced.

Consequently, this willreduced the eutrophication process.


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