Transboundary pollution of hydrosphere

Тип работы:


Детальная информация о работе

Выдержка из работы

Transboundary pollution of hydrosphere

Transboundary pollution — the pollution that occurs in one country but is able to be reason of damage in another country’s environment, by crossing borders through pathways like water or air. In our work we will talk about only water contamination.

Pollution can be transported across hundreds and even thousands of kilometers. The incredible distances that pollution can spread means that it is not contained within the boundaries of any single nation. This is why it is called `Transboundary Pollution'. One of the problems with transboundary pollution is that can carry pollution away from a heavy emitter and deposit it onto a nation whose emissions are relatively low. Another problem with transboundary pollution relates to the quote above. Due to the fact that `All things connect', the heavy pollution that is evident in the developed world also becomes evident in remote areas.

Water body

Lake Victoria is the largest lake in Africa, and according to various sources, the fourth and second in the world in area (68,100 km?). The lake with a 3450 km-long shoreline lies at altitude of 1135 meters above sea level, has a mean depth of 40 meters and maximum depth of 80 meters. Lake Victoria basin is used by communities and industries as a source of food, energy, water and transport. The lake is also a sink for human, agricultural and industrial waste. The Lake provides employment for up to 30 million people. The Lake’s catchment area of 258,700 square kilometers has a GDP of US$ 300−400 million and supports nearly one-third of the total population of East Africa. The Lake is the source of River Nile, which is renown for whitewater rafting and flows to Egypt through Sudan.

Name for the lake gave the British explorer Speke, who in 1858 was the first European was able to get to him and named it in honor of Queen Victoria. On the shores of the lake is home to over 30 million people, is the real heart of the economy of East Africa.

This huge lake is among the three countries: Uganda, Kenya and Tanzania. Also, for population of these 3 countries it is a source of water. However, the level of pollution of water has become very high such that the capital of Uganda, Kampala may remain without drinking water.

Several years ago, the lake was a symbol of animal biodiversity. Unfortunately, everything was changed when the 50-years people started to entering Nile perch (popular fish among Europeans) in lake. On the one hand, the Nile perch has become an important commercial fish for local residents, many of whom gave up another economic activity for the fish trade. On the one hand, the Nile perch was a formidable predator, will destroy many of the other fish in Lake (once there were more than 200).

This was a real crisis, as the entire northern part of the lake is gradually turning into a dead zone. The lake here is absolutely green because of the abundance of algae, serious water purification.

In addition, all wetlands that used to be natural water filters that prevent harmful substances penetrate into the lake had completely disappeared from industrial and tourist development of the banks of the lake. This means that the dirty water gets directly into the lake, which will result in contamination of a tragedy for the people in the near future.

Sources of pollution

Lake Victoria is at the big risk to die from pollution

The causes of rising pollution levels in the Lake are as many as they are diverse and each of the three East African nations is culpable. The Lake has for along time been a sink to excessive nutrients and untreated effluent that have led to fish die-offs, algal blooms and the spread of hyacinth, a ferocious waterweed. Although mostly eradicated now, the remnants of hyacinth on Lake Victoria deplete dissolved oxygen, sunlight and are an obstacle to water transport. Along the shoreline, hyacinth provides habitat for malaria mosquitoes and snails which habour bilharzia parasites.

1) In Uganda, have a lot of sources of pollution such as:

— deficient sewage and industrial wastewater plants

— small-scale workshops

— waste oil from parking lots

— car repair garages

are major sources of pollution load for the lake. The sewer system in Kampala city serves only a small fraction of the city population and only 10% of all sewage generated in Kampala gets treated. Guesthouses, slum dwellings and industries discharging untreated wastewater in Nakivubo channel, which flows into Murchison Bay contribute lachrymal pollution load and depleted oxygen levels in Lake Victoria. Also riding of motorboats churns up a trail of black sewage sludge in Nakivubo channel. In addition, Nakivubo Channel carries approximately 75% of the nitrogen and 85% of phosphorus nutrient load discharged daily into Murchison Bay. The high nitrogen and phosphorous levels are responsible for excessive eutrophication and algal blooms seen in the Bay.

2) Murchison Bay is covered in a green floating blanket of algae that is as viscous as wall paint. Algal blooms clog water treatment plants, deoxygenate lake water causing fish die-offs and cause a skin condition known as swimmers itch. Murchison Bay is home to water treatment plants that supply Kampala city and neighboring towns. Uganda’s National Water & Sewerage Corporation (NWSC) is experiencing rising treatment costs because lake water is dirtier and increasingly expensive to treat to potable quality. Ironically, the single largest polluter of Lake Victoria is NWSC’s Sewage Treatment Plant at Bugolobi, which discharges 15,000 m?/day of inadequately treated sewage into Murchison Bay.

3) Kenya’s side is not a good situation too. Towns of Kakamega and Kisumu discharge inadequately treated sewage in rivers draining into Lake Victoria because of deficient treatment plants. Kisumu’s sewage plant at Kisat with a design capacity of 9000 cubic meters now receives 15 000 cubic meters of effluent, much of which flows into Lake Victoria without treatment. In Kakamega, sewage lagoons at Nabongo have been neglected for more than 3 years and are grossly inefficient.

4) Also, Tanzania’s town of Mwanza located near Lake Victoria discharges large quantities of untreated waste into the lake. Waste from:

— fish processing factories

— oil processing plants

— textile facilities and tanneries

are discharged into the lake without pre-treatment. Studies by Tanzania’s University of Dar es Salaam on lakeshore sediments to investigate their heavy metal content revealed high concentrations of Zinc, Copper and Lead metals. Another study by Makerere University in Uganda identified alarming levels of lead in yams cultivated in Nakivubo wetland through which Kampala city’s effluent flows before discharging into Lake Victoria. In both studies, the metals were attributed to industrial sources.

Clearly, more than anything else, it is discharge of untreated effluent and the lack of enforcement of discharge standards that are killing Lake Victoria.

5) Sources of heavy metal pollution of Lake Victoria is of interest due to its economic and domestic implication in East Africa. Sediments from the shore of Lake Victoria and from some streams flowing into the lake have been analyzed for their heavy metal content using Energy Dispersive X-Ray Fluorescence (EDXRF) analysis. The samples were collected from seventeen different locations around the Municipality of Mwanza divided into three zones according to their activities. The results show that sediments from Mwanza North, which is least in anthropogenic activities, contains Cr and Co in addition to metals of terrestrial origin (K, Ca, Ti, Mn, Fe, Rb, Hg, Y, and Zr), samples from Mwanza Central, which is the town center, contains high concentrations of V, Cu, Zn and Pb, and samples collected from Mwanza South, which is the industrial area, contains the highest concentrations of V, Cu, Zn, As and Pb. It is concluded that the industrial and sewage wastes discharged into the lake are the main sources of the heavy metal contamination of Lake Victoria. Further studies will be required to assess detriments of these pollutants to human and aquatic life before policy for the factories responsible is put in place.

Qualitative and Quantitative characteristics

1) Heavy metals pollution can arise from many sources but most commonly arises from the purification of metals, e.g., the smelting of copper and the preparation of nuclear fuels. Electroplating is the primary source of chromium and cadmium. Through precipitation of their compounds or by ion exchange into soils and muds, heavy metal pollutants can localize and lay dormant. For example:

- Hg (Mercury) — Sewage containing mercury is released for outside chemicals. The mercury accumulates in sea creatures, leading eventually to mercury

- Cu (Copper) — is an essential substance to human life, but in high doses it can cause anemia, liver and kidney damage, and stomach and intestinal irritation. People with Wilson’s disease are Copper is an essential substance to human life, but in high doses it can cause anemia, liver and kidney damage, and stomach and intestinal irritation. People with Wilson’s disease are at greater risk for health effects from overexposure to copper. Copper normally occurs in drinking water from copper pipes, as well as from additives designed to control algal growth.

- Cr (Chromium) — is used in metal alloys and pigments for paints, cement, paper, rubber, and other materials. Low-level exposure can irritate the skin and cause ulceration. Long-term exposure can cause kidney and liver damage, and damage too circulatory and nerve tissue. Chromium often accumulates in aquatic life, adding to the danger of eating fish that may have been exposed to high levels of chromium.

2) Nitrogen (N) — accumulation reduces biodiversity, acidifies soil and water, degrades coastal environments, reduces forest productivity, contributes to the greenhouse effect, and depletes the ozone. Reactive nitrogen is so high in the developed world that we’re polluting ourselves out of clean air, drinking water, and biodiversity

3) Phosphorus (P) — behavior in water is as a fertilizer, accelerating plant and algae growth. When plants and algae die, bacteria consume oxygen that is dissolved in the water. When this happens, less oxygen is available for fish and aquatic life that need oxygen to survive. Excess phosphorus in drinking water is difficult to remove, and also can require an increase in treatment chemicals which adds cost.

4) Fertilizersэ — consist of three primary plant nutrients:

nitrogen and phosphorous with smaller amounts of potassium. The first two are the most important as pollutants. Nitrogen fertilizers containing nitrates can contaminate groundwater because nitrates are highly soluble in water. At high levels, nitrates can poison humans, particularly children. Lower levels of nitrates can also be deadly to amphibians. Certain forms of nitrogen are released as gases, contributing to acid rain and climate change. Rainwater runoff brings fertilizers into streams, rivers, lakes and oceans.

5) Pesticides — are mostly modern chemicals. There are many hundreds of these compounds, and extensive tests and studies of their effect on humans have not been completed. That leads us to ask just how concerned we should be about their presence in our drinking water. Certainly it would be wise to treat pesticides as potentially dangerous and, thus, to handle them with care.

Ways to reduce the impact

Firstly, 3 countries which are bounded with Victoria Lake: Uganda, Kenya and Tanzania must make some rules to reduce sewage pollution. They must perform the methods below.

The main problem of Lake Victoria is the wastewater from sewage. To reduce it we should use this methods:

a) We should treat sewage water before its release into rivers, after that most problems associated with pollution would be solved. Removal of contaminants is the main objective of treatment of sewage water. Before the actual treatment of water, effluents are pretreated. The process of pre-treatment helps in the separation of oils, greases, gravel and sand from polluted water. This process is carried out by filtration of sewage water.

b) The third method is: biological wastes dissolved in water are treated with microbes. It helps in converting wastes into a solid mass which can be easily separated later on.

c) Restoration of wetlands is one of the important means of treating sewage water. Wetlands allow to process sewage water naturally, without the use of any artificial method/technique. The idea behind restoring wetlands is that bacteria present in them would dilute the nitrates and phosphates. The same process takes place in sewage water treatment plants except that, here (in wetlands) it is carried out naturally.

Sewage treatment is the important thing, because 30 per cent of all pollution is comes from wastewater of sewages. It is very difficult to solve this problem in one day, we should spend a lot of time to find a solution by discovering and experiments.

pollution lake transboundary

Заполнить форму текущей работой