Pollution of the Oceans

Pollution & the sea

Like oil and waterOne significant impact of human activity upon the oceans is marine pollution. It is not just oil pollution from accidents and illegally discharged tank cleaning wastes. Besides the high visibility of oil spills upon marine environments the total quantities involved are reduced by those of pollutants introduced from other sources (including domestic sewage, industrial discharges, leakages from waste tips, urban and industrial run-off, accidents, spillage, explosions, sea dumping operations, oil production, mining, agriculture nutrients and pesticides, waste heat sources, and radioactive discharges).

Land based sources are estimated to account for around 44 percent of the pollutants entering the sea and atmospheric inputs account for an estimated 33 percent. By contrast, maritime transport accounts only for around 12 percent.

Toxic chemicals

The input of man-made chemicals to the oceans potentially involves a huge number of different substances. 63,000 different chemicals are thought to be in use worldwide with 3000 accounting for 90 percent of the total production tonnage. Each year, anywhere up to 1000 new synthetic chemicals may be brought into the market.

Of all these chemicals some 4500 fall into the most serious category. These, known as persistent organic pollutants, they're resistant to breakdown and have the potential to accumulate in the tissues of living organisms (all marine life), causing hormone disruption which can cause reproductive problems, induce cancer, suppress the immune system and interfere with normal development in children.

Oil

The most visible and familiar form of pollution is oil pollution caused by tanker accidents and tank washing at sea, and in addition to the gross visible short term impacts, severe long term problems can also result. In the case of the Exxon Valdez (name of an oil tanker) which ran aground in Alaska in 1989, biological impacts from the oil spill can still be identified 15 years after the event. The Prestige, which sank off the Spanish coast late in 2002, resulted in huge economic losses as it polluted more than 100 beaches in France and Spain and effectively destroyed the local fishingindustry.

Alyssa