(18) Environmental Law

Plastic Bags and the marine environment

IMO - Marine Environment

Marine environment


Marine Environment

State of Marine Environment

Pollution enters the marine environment through dumping, through discharges from the operations of ships, through land-based sources, and through the atmosphere (pollutants end up in the atmosphere from land-based sources). The GESAMP has determined that only 10 percent of marine pollution comes from dumping and 1 percent is a result of sea-bed activities. The main culprit of marine pollution (77 percent) is pollution coming from land-based sources.

Despite the plethora of national and international instruments devoted to the prevention and elimination of sea pollution, the results, in terms of environmental improvement, are mixed. According to a GESAMP study: Although there have been some notable successes in addressing problems caused by some form of marine pollution, and in improving the quality of certain coastal areas, on a global scale marine environmental degradation has continued and in many places has intensified.

The GESAMP report has placed emphasis on the increasing global problem of eutrophication, that is, the increased biological production in coastal and near shore waters, because of the input of nutrients from sewage and agricultural fertilizers.

According to the GESAMP, eutrophication is “among potentially the most damaging of all human influences on the oceans, in terms both of scale and consequences.” The GESAMP has warned that excessive nutrient inputs “can turn marine areas into wastelands.” The GESAMP has determined that sewage is a problem of high priority in all regional seas. After sewage, environmental issues that need to be addressed with urgency include sediment mobilization, Persistent Organic Pollutants (POPs), heavy metals, and physical alteration.

The sea disposal of low-level radioactive waste has become controversial. Although in the 1970s such practice was tolerated, in the 1990s the London Convention prohibited the dumping of low-level radioactive waste at sea.

The GESAMP has determined, however, that low-level radioactive wastes do not present as high a risk as other wastes, especially toxic wastes. The GESAMP results are based on a 1993 IAEA study that evaluated the comparative risks of ingesting chemical carcinogens versus those of ingesting radionuclides through seafood consumption. The study was prompted by a need to see the risks associated with the disposal of low-level radioactive waste in the appropriate context.

The IAEA study concluded that the incremental risk associated with the contamination of seafood from the sea disposal of low-level radioactive waste is three or four orders of magnitude lower than the risk posed by what are considered toxic chemicals. The study examined the environmental effects of reprocessing plants located in Sellafield (United Kingdom), La Hague and Marcoule (France; now shut down), Trombay (India), and Tokai-Mura (Japan). It was concluded that nuclear power reactors discharge small quantities of radioanuclides, that they are generally well regulated, and that they should not be a source of concern. The GESAMP recognizes, however, that the use of nuclear power is an emotive issue and that public opinion on this topic is unlikely to change.

Although low-radioactive waste is not an issue of concern, the dumping of nuclear waste that comes from the decommissioning of nuclear weapons, nuclear military installations, and obsolete nuclear vessels, is. The GESAMP has singled out Russia for the illegal disposal of high-level radioactive waste at sea, which is in violation of the London Dumping Convention that banned such practice since its adoption.

The dumping activities of Russia, especially those involving the dumping of reactor assemblies containing spent fuel and of entire nuclear submarines, are of concern. The GESAMP has insisted that the difficulties involved in the decommissioning of military vessels, and particularly of nuclear submarines of the Russian North Fleet, suggest that such activities pose threats to the marine environment. There have been a number of accidents involving nuclear-powered and nuclear-armed vessels.

The GESAMP has identified several sources of marine pollution: sewage treatment plants, development activities that lead to discharges of sediments, and mariculture facilities. Diffuse sources of pollution include agriculture, wide scale forestry, and development activities that lead to increased mobilization of the soil. In terms of contaminants, substances of concern include mercury and lead, POPs, and what has been called the “dirty dozen.”13 The GESAMP has concluded that most metallic compounds should be of concern at a local level and only exceptionally at a regional scale.

Salt discharged from desalination plants in high volumes and concentrations has adverse effects on regional areas, for instance, the Persian Gulf and the Red Sea. Heat discharges have detrimental effects on small and poorly flushed water bodies. Pollution from vessels is caused by the operational discharges from ships, for instance from cleaning of tanks or discharges following accidents. Although vessels contribute a small percentage of marine pollution (12 percent of the total), they are usually perceived as one of the main contributors to marine pollution because of the large publicity that oil spills generate. The GESAMP has concluded that the releases of hydrocarbon compounds from routine operations, such as oil exploitation and exploration and shipping, are relatively well regulated (through the MARPOL Convention 73/78).Large oil spills create problems but are of “limited significance” on spatial and long-term scales. Oil is not the worst pollutant of the seas.

Heavy metals (lead, mercury, and cadmium), however, are potent pollutants. Nitrates and phosphates from agriculture could cause a significant amount of eutrophication and should become an issue of priority.

Other contaminants include polycyclic aromatic hydrocarbons (PAHs), which are likely to increase because of the increasing exploitation of the sea-bed and remain troublesome because of their appearance in seafood. Litter and sediment mobilization are likely to be issues of primary concern at the local and regional levels. Physical alteration of coastlines, as a result of cumulative impacts, is an issue on which the GESAMP has focused its attention. The GESAMP has warned for action to be taken to prevent impacts on coastlines from increased sediment, excavation works, forestry, agriculture, beach development, and construction of hotels and marinas.

Habitat destruction, dredging, and infilling operations are considered major problems, especially in the Red Sea/Gulf of Aden. Sand and gravel extraction from the sea-bed is also a concern in the North East Atlantic and the Irish Sea. The GESAMP study has emphasized that certain marine environments are more sensitive to pollution than others and, thus, require special attention, such as coral reefs, sea-grass beds, coastal wetlands, mangrove forests, shallow coastal waters, and small islands.Polluted groundwater can affect the marine environment adversely. Slow but persistent seepage of groundwater takes place along most of the world’s coastlines and eventually may lead to pollution.

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