Marine pollution

Marine pollution is one of the 21st centuries greatest environmental problems. In 1992 at the United Conference on Environmental and Development held in Rio de Janeiro it was concluded that land-based pollution was considered to be the major source of marine pollution.

Marine pollution is defined as "direct or indirect introduction by man of substances or energy into the marine environment resulting in deleterious effects". A general presumption suggested marine pollution was not a problem because or the sheer size/volume of the worlds marine environment and this would dilute any pollution, but as the problems in the North sea has proven this statement wrong as this is a regular dumping ground for many countries and tides keeping the waste in the same area.

Oil is popular idea for marine pollution as it is the only type that gets media coverage. Although is causes serious effects on whole ecosystems, it is not that common and the damage is reversible.

Oil gets into water by accidental spills from ships, trucks or pipelines. For example the oil tanker Exxon Valdez ran aground in 1989, spilling more than 38million litres off the shoreline of Alaska. The oil covered 1770km of shoreline including many islands killing thousands of birds and sea mammals like sea otters. Fisheries were affected causing economic concern for Alaska's salmon and herring trade.

The oil floats on the water surface preventing complete penetration of sunlight to the ocean floor, so marine plants are not able to efficiently photosynthesise, leading to a complete change of food chain.

Another source of oil spills is from offshore rigs. In 1979 the Ixtox I well spilled 530million litres in the Gulf of Mexico. Another problem with offshore platforms is the accidental release of dangerous gases associated with oil extraction. Any flammable gases are potentially liable to cause explosions, that could kill humans as well as other marine life, destroy parts of the rig that fall into ocean and cause damage so an oil spill is possible.
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Petroleum products are poisonous if ingested by animals so this can affect all trophic levels in a food chain because of bioaccumulation. Also spilled oil may be contaminated with other harmful substances like Polychlorinated Biphenyl's (PCBs) these are not degradable so, because of Biomagnification affects the food chain.

Oil is a Transboundary pollutant as one country's oil may spill on another country who then experience all the problems. This is one reason why there is a difficulty controlling.

After the Exxon incident a new regulation was bought about to fit all the tankers with a ...

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