تم اضافتي للموضوع بعد يومين من طرحي للموضوع ليش هالردود السلبية من اكثر من شخص الموضوع نزل في الصفحه الثالثة من الردود وعلى كلا شكرا على كل شي
الموضوع::::::
هذا هو التقرير والسموحه نمك على التاخير بسبب الامتحانات (يعني لازم تراعون ضروفنا اخوان)
Pollution is an unwelcome concentration of substances that are beyond the environment’s capacity to handle. These substances are detrimental to people and other living things.
In an undisturbed ecosystem, all substances are processed through an intricate network of biogeochemical cycles, such as the nitrogen and carbon cycles. During these cycles, substances are taken up by plants, move through the food chain to larger and more complex organisms, and when the latter die, are decomposed (broken down) into simpler forms to be used again when they are taken up by plants. Biodegradable substances are those that can be broken down by the environment’s biological systems. Pollution occurs when the environment becomes overloaded beyond the capacity of these normal processing systems.
Examples include:
* An excess of normally helpful substances, such as the nutrients nitrogen and phosphorus.
* An excess of substances that are harmless, and perhaps even necessary in tiny amounts, but toxic in concentration. Copper, for example, is necessary in small amounts for healthy plant growth, but becomes a pollutant if it occurs in greater quantities.
* Synthetic (human made) compounds that are poisonous in the environment, often even in trace amounts, such as DDT, dioxin, PCBs and organochlorines (see Enviro Facts "Toxic waste" and "Poison, farmers and wildlife").
* Substances that, in any amount, are not biodegradable, such as plastics and highly persistent chemicals like DDT and other organochlorines.
Some pollutants kill living organisms outright, other sub-lethal pollutants do not kill, but may cause long-term biological damage, interfere with organisms’ reproductive cycle, or make them more vulnerable to disease.
TYPES OF POLLUTION
Pollutants can be grouped according to the main ecosystem which they affect. One pollutant often affects more than one ecosystem.
AIR
Sulphur dioxide produced through the burning of coal, causes acid rain and respiratory problems. Nitrogen oxides and volatile hydrocarbons from vehicle emissions, combine to form photochemical smog which causes respiratory problems. Carbon monoxide from vehicle emissions, restricts oxygen uptake, causes drowsiness, headaches, death. Carbon dioxide produced during the burning of coal enhances global warming. CFCs used and aerosols, refrigeration, airconditioning and foam- blowing industries destroys the ozone layer. Methane from feedlots and rubbish dumps enhances global warming. Noise from industry and traffic affects hearing and is stressful.
FRESH WATER
Sewage contains pathogens which cause typhoid, cholera and gastroenteritis if there is inadequate sanitation. Nutrients in sewage cause eutrophication. Fertilizers used in agriculture cause eutrophication. Silt build up in freshwater ecosystems, caused by inappropriate agriculture, smothers aquatic organisms. Pesticides used in agriculture and by the health services are toxic and interfere with breeding of mammals and birds. Toxic XXXXls which are produced by industry are health and life threatening.
MARINE
Sewage released into marine systems due to inadequate sanitation will cause the diseases mentioned above. Fertilizers used in agriculture cause eutrophication. Oil spills from tankers smother marine plants and animals. Plastics in the sea causes the death of marine animals. Pesticides used in agriculture and by the health services also causes the death of sea life.
LAND
Solid waste is classified as hazardous (radioactive, pesticides, medical, poisons) which is health and life threatening; or non-hazardous (domestic, urban, mining, industrial, scrap XXXXl.) which is unsightly and disposal takes up much space.
DEALING WITH POLLUTION
In the past, most approaches to handling pollution could be summed up by the phrase `dilution is the solution to pollution’. However, pollution levels have increased so much in amount and toxicity that this approach is no longer acceptable. An alternative approach is source reduction, i.e. a reduction in the amount of pollution where produced.
Point source pollution: Pollutants are produced from a stationary location, e.g. industrial plants, mines, and municipal sewage works.
Non-point source pollution: This pollution cannot be traced to a specific spot, and is far more difficult to monitor and control. Common examples are veld fires, motor vehicle emissions, fertilizer runoff, sediment from construction and erosion, plastic packaging, and gases from aerosol cans. Some non-point sources can be addressed by laws, such as banning CFCs (chlorofluorocarbons), or requiring car manufactures to install emission controls.
Polluter-must-pay principle: This means that a polluter should bear the costs of avoiding pollution, or remedying its effects. This principle is difficult to apply when the source of pollution cannot be identified, as is often the case with atmospheric pollution. The principle can be usefully applied following a pollution disaster, such as an oil spill from a tanker. However, the consumer often pays for such pollution costs. For example, Eskom estimates that the fitting of scrubbers (see Enviro Facts "Energy and environment") on the chimneys of their power stations will increase the cost of electricity by 30%.
The polluter-must-pay-principle is implemented in Europe and North America, and is increasingly applied in South Africa.
MOVEMENT OF POLLUTION
Pollution does not stay in one place but is moved around the world by air and water, as well as by living organisms. Even in Antarctica, birds and marine mammals show traces of pollutants such as DDT and PCBs. Some pollution is deliberately moved abroad. Companies restricted by pollution control regulations at home, sometimes move their plants to other less restrictive countries, as was the case with the plant involved in the Bhopal chemical disaster. Or while remaining at home, they may sell products abroad, that are classed in their own countries as too dangerous for sale, such as banned pesticides. In some cases hazardous waste may also be shipped abroad, generally from industrialised countries to developing countries willing to accept such waste for a fee, despite the hazards (see Enviro Facts "Toxic Waste"). When such pollutants turn up again in the originating country, as when food is imported that contains banned pesticides, the process is said to be completing the `circle of poison’.
All books are available from Russel Friedman Books, PO Box 73 Halfway House 1685. Tel. 011-70022300/1.
Eskom’s environmental education brochures. Available from Eskom, address below.
Enviro facts "Acid rain", "Energy and environment", "Energy options", "Ozone", "Global warming", "Precious water", "Toxic waste", "Marine pollution", "War on waste".
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