The EGG
The EGG
by Aruho Rogers
Eutrophication means nutrient enrichment which all water bodies undergo during their lives. Eutrophication results in lowering of water quality for domestic and recreational uses, following discharge of wastes containing some nutrient salts into water bodies.
The problems do not come from the nutrients themselves but from the changes induced in the aquatic productivity. The most important nutrients that cause eutrophication are nitrates and phosphates from fertilizers.
Primarily some of the causes of sea pollution are:
Domestic wastes and sewerage. Discharge of partially or not treated sewerage in seas is the most common sea pollution in big cities.
Discharge of sewerage leads to:
-Depletion of oxgyen content caused by oxidation of organic matter.
-Stimulates algal growth and a shift in the algal frola leading to
production of obnoxious blooms and floating scums. This has been a major
problem of pollution and the situation is very alarming. An example is the
algal blooms that covered part of the North Sea.
Sewage discharged from coastal settlements, sometimes untreated, into coastal waters where it generates direct healthy hazards for recreational bathers as well as marine organisms.
Discharge of industrial wastes and effluence, for example, the breweries and paper and textile industries cause serious sea pollution. Seas like the Irish Sea have been destroyed due to leaks from the nearby nuclear power station. Oil is also a major source of sea pollution. Oil spillages from tankers or off shore wells occur frequently all over the world. Use of detergents to dispense oil slicks is often more damaging to the environment than the oil its self. Though oil may have little effect on the fish food in the sea, one thing is certain. Oil kills sea birds. Resistant objects such as jerricans, tyres, plastic or metal objects can act as pollutants, too.
Land drainage from urban areas,industrial and waste disposal sites is often contaminated with heavy metal or hydrocarbons. Biological concentrations of heavy metal in marine foods gives lethal doses as occurred far back following the discharge of mercury into coastal waters at Manimata Japan.
Mercury concentrations in fish led to the death of many human and animal predators that fed on fish. Thisresulted in the death of many people around the bay and many more suffered severe damage to their nervous systems. Although there is little likelihood of this happening on a larger scale, its fortunate that limits are now being put on the discharge of mercury and other dangerous chemicals into the environment.
Pesticides and biocides. Pestcides are substances used for pest control but their mode of activity often extends their limits then they become biocides. Unlike other natural pollutants like dust, many of the pesticides tend to retain their biological activity for a long time. They are persistant and their concentration builds up as they are transferred to different stages.
Food webs. Serious cases of fish mortality have occurred following the leaching of pollutants from nearby agricultural fields to the neighbouring seas.
Asbestos is widely used as an insulating material and chances of its asbestos waste reaching water bodies are high. It's a fibrous mineral which is highly resistant to disntergration. Asbestos may lead to cancer of the lungs, stomach and intestines.
Fertilizers also have a harzadous effect on water bodies. Though fertilizer use has been known to be beneficial to ecosystems in increasing food production, fertilizers lead to detoriation of water resources caused by eutrophication as a result of washing of nutrients into the water.
Silt. The dirty particles which are carried from land to water make up silt though silt beneficially enriches fisheries. Silt through soil erosion has led to sea pollution.
Thermal pollution. Many industries discharge heat in form of hot water or air into the environment particularly the seas. This heated water at high temperatures can be lethal to aquatic habitats. Some aquatic animals are killed when the water is too hot and if it's less hot it leads to bacterial diseases.
Further research and better marine pollution monitoring is urgently needed. Regulations to control marine pollution are very hard to police, particularly in open oceans. Easy profits can be made from criminal dumping, especially since waste disposal has become a major problem for human societies.
Noxious chemicals and radioactive wastes are of course eventually dispersed by wave action but if discharged into the shallow area of the continental shelf, they may damage the ecosystem before effective dispersal can occur. Small seas are particuraly vulnerable.
More important is an awareness of the problem and avoidance of indiscrimate use of scientific discoveries, for example, banning DDT and other chemicals that don't pass the tests.
Unfortunately, we are about to be caught in our own traps. The problem needs urgent attention if we are to live better in this global village.
However the setting up of government bodies to promote conservation are signs that leaders are beginning to take the problem seriously.