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.
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 double hull but of 3,500 tankers only 251 have them.
Hazardous waste is produced by every industry about 400million metric tonnes world wide every year. This, like oil, is a Transboundary pollutant so one countries waste affects many others. In 1979 2.4million tonnes of titanium dioxide was dumped in the North Sea. This area has been the main recipient for this sort of waste as it is prohibited in other places like the Mediterranean Sea.
In places like the North Sea the amount of dumped contaminants is extremely high causing algal blooms, toxic red tides and viral death of marine mammals. Also in the North Sea there is high amounts of lead pollution, this accumulates in the marine life, causing toxic effects. The problem with this pollution is the different sources, so controlling them is much more complicated: 58% of the lead is from vehicle emissions.
Pollution is released from factories in the effluent discharged into rivers leading to the North Sea, although the factories may be releasing legal amounts of pollution in the effluent, it all accumulates because off all the factories along all the rivers in the different countries leading to the North Sea.
Another problem in the North Sea is over-fishing. This is when there is a decrease in fish caught even though fishing efforts are increased.
Herring was seriously over-fished in the North Sea, in 1952 there was 2million tonnes this was reduced to 0.25million tonnes in 1974. Germany, Denmark, Netherlands and Norway were also using the North Sea to fish, as well as Herring, Cod, Haddock and Plaice.
There are several methods that could help resolve this problem:
a. Reducing the total permitted annual catch.
b. Reducing mesh size. So younger fish are able to grow and reproduce.
c. Limiting fishing areas.
d. Closed season.
The major problem with these proposals is the difficulty to enforce, countries need to agree an international legislation and organise an international enforcement team.
Sewage works by the Coast can and will dump sewage in to the sea and rivers going to the sea. In periods of heavy rain untreated sewage is released. Especially in tourist coastal towns like Bournemouth many people live in and visit the town during the year, even during the winter surfers, kayakers and sailors use the beach. Sewage can be a big danger to people’s health and to marine life.
An increase of organic waste in a marine environment can lead to Eutrophication, which involves an increase of bacteria needed to decompose the organic material this leads to reduction of oxygen in the water.
Promises of longer outfall pipes by 2002 by local water authorities but at a cost of 300million pounds, making this promise a very expensive process.
The organisation Surfer Against Sewage (SAS) raise awareness to the public and the Government about the problems of sewage and the damage it can do to people who use the sea regularly, like surfers. Bournemouth sewage works have a special phone number available to anyone who wishes to find out when the last sewage was released through the pipes into the sea. Although this doesn’t completely resolve the problem, it does help prevent any danger to humans only.
A specific consequence is the declining of Coral reefs. Coral reefs are an accumulation of calcareous exoskeletons of coral animals, calcareous red algae and molluscs. Built up layer by layer. They exist in tropical conditions, in water never cooler than 20’C.
In areas of coral reefs a big tourist industry has been built up, increasing the amount of pollution and destructive fishing using dynamite to kill large amounts of fish and producing pieces of coral that is sold to tourists.
Nutrient run-off from the land causes Eutrophication leading to large algal blooms that smothers the coral.
Global warming and UV radiation are suggested to be the cause of ‘bleaching’ which is the discolouration or loss of symbiotic zooxanthellae. Outbreaks started after the 1970s. As the oceans get warmer the rate of photosynthesis increases which creates increased concentrations of free-radical toxins, that affect the zooxanthellae.
A reef can slowly recover form this but if bleaching keeps on taking place it may be impossible for recovery. This makes coral unable to deposit calcium carbonate skeleton that makes the foundation of the reef.
In the Ecologist report ‘Climate change’ November 2001, they have predicted, that because of global warming raising the temperature of the oceans, coral reefs are thought to be ‘unsavable’.
In the case of the sewage and coral problems, money is the problem. In developed countries money isn’t too much of a problem for treatment of sewage pollution but projects are not a big priority. Countries where there are coral reefs, the tourisms it attracts that causes damage and pollution also brings money to the local people.
Another problem is because most pollution is a Transboundary pollutant, so neighbouring countries, like the 5 countries surrounding the North Sea, should work together to resolve the problem by creating international legislation with international enforcement.
Marine pollution is a very wide spread area and a problem in resolving this is it is seen as one big problem. It needs to be dealt with in separate sections.