Temps de lecture :8 minutes
One-third of global marine oil transportation passes through European waters. Not only oil tankers, but various other cargo ships pose a constant threat of small to medium-scale oil pollution from illegal dumping of oily wastes with at least 3000 major events per year around Europe. The devasting consequences of occasional « newsworthy » accidents are outmatched by constant small, but still harmful, releases from oil industry transport.
Ninety per cent of oil and refined products are transported by the sea. Accidents resulting in massive oil soills, with their image of soiled beaches and dying birds are newsworthy accessible to the mass media, affect public opinion and mobilise policy-makers .However, such dramatic accidents occur only infrequently and represennt only a small fraction of the pollution problem at sea. Routine tanker operations lead to release of noxious ballast water and tank washing residues. Furthermore, fuel oil sludge,engine room wastes and foul blidge water, produced by all types of ships, also end up in the sea.
Out of the 1,5 to 1,8 billion tonnes of crude oil transported worldwide yearly-35% of total marine transportation-Europe is the main recipient with nearly 500 milliontonnes of crude oil and 250 to 300 million tonnes of refined products per year. These ratios still are rising due to increased consumption. Moreover, many oil tankers transport their cargo to other destination trough Europe&n waters, meaning that the total amount of crude oil passing through EU waters could well be over 1 billion tonnes ( …). The Mediterranean alone sees 360 million tonnes of oil and refined products per year transported on its waters, approximately 22% of global total.
Without efficient and strict controls as a deterent, and to lower costs, oil tanker crews release noxious residuals at sea. It is estimated that at least 3000 major illegal hydrocarbon dumping incidents take place in European waters yearly, amounting to total amounts of between 1750 and 5000 tonnes in the Baltic Sea and more than 400 000 tonnes in the Mediterranean (…). Oil released into European seas as a result of operational discharges greatly exceeds the amount released during accidental spills : yearly, in the Mediterranean, they can add up to nearly 20 times the amount that was spilled by the « Prestige » off nothern Spanish coasts in 2002. Despite international and domestic conventions and legislation, oil dumping in the sea remains a troubling, unsolved and uncontrolled environmental problem.
What is released and why ?
Oil pollution from routine tanker operations includes ballast water, tank washing residues and other oil mixtures from the engine room and bilge waters. Such pollution is also known as slops. When old tankers offload cargo and prepare to travel empty, they must take on large quantities of ballast water to maintain the proper balance of the ship. When the ballast water is discharged, oil residues are released as well.
Releasing ballast water is discharged, oil residues are released as well. Releasing ballast water should be done in special receiving facilities in ports, but is generally done at sea, to avoid extra costs (0,15 € per m 3). When switching cargoes, hulls are washed to remove oil residue on hull walls (about 0,5% of the total load). Tank washing must be done at sea, as the vaporous and fumes emitted during the process violate air quality standards in the urban areas where ports are located. Such washings may be done by spraying pure oil or water into the tanks in order to remove oil residues. The remainings from a tank washing should typically be stored in slop tanks, discharged at reception facilities and tanks inspected at each port of call. But this is rarely done, and c leaning residues are also left at sea. For the reception facilities, the value of oil may be small relative to the cost that it takes to treat and refine it. There are also regulatory concerns, as laws may classify any unwanted water associated with slops as toxic waste, thus subjecting the port facilities do not want to handle the waste oil.
Sludges include engine room wastes and foul bilge water from all types of ships. Due to the low quality of ship fuel, only part of it is effective for propulsion. Before being burnt, fuel can be centrifuged, generating residues ( 2% of total fuel load) which are stocked in bilges. Ships also use a large ampount of engine lubricants that often leak and end up in bilges.
Generally, sludges are stocked in a seperate specific tank. Various lubrication and other oils spilled during ships operation may also be stored in such tanks, which need to be emptied regularly. Quantities are to be recorded in the « Oil Record Book » required by the MARPOL Convention and noxious residues unloaded in adapted facilities in ports. The certificate delivered by the collecting company is also stored in the Oil Record Book. In practice, boats rarely unload in ports for various reasons :
– Cost : highly variable, can reach 200 euros per m 3 .
– Increase dock time. Unlike slops, sludges cannot be unloaded simultaneously with other ship operations, making the dock time longer and more expensive.
– Lack of proper facilities to accept and treat sludges in harbours. Facilities’ availability varies depending on country, region and activity level, which may or may not economically merit a private collection system.
– Existing regulations are not applied : for example, in France, the current number of boat inspections is lower than 10% whereas European legislation calls for 25%. Since there are no existing measures forcing ships to unload their waste in harbour facilities, these costs are considered « avoidable ».
– Lack of sanctions : the chances of being « caught in-the-act » while illegaly unloading fuel or sludges are very low today.Without sufficient incentives for port facilities to receive or for vessels to off-load slops and sludges, and without regulatory requirements and enforcement to mandate their off-loading, the shipping industry must nevertheless discharge residues somewhere. Thus,it is often done illegaly at sea, along regular shipping routes or in the area of recent oil accidents, so that these wastes might mix with accident residues and go unnoticed (…).
Impacts on the Environment !
The impact depends on the type of oil, amount spilled,weather conditions and dynamics of the area or the ecosysytem. When crude oil reaches water, 16% is diluted, 22% is biodegreded into simpler substances by either sunlight or bacteria, and the remaining amount has negative impacts on the environment. The less dense component (15%) eventually evaporate into the atmosphere. This petroleum then reacts to form greehouse and acid gases similar to those from the combustion of oil. The heavier portions of crude oil coagulate into tar patties, a sticky oil and water mixture, and may even wash upon shore or sink to the bottom. The 28% that sinks to the bottom of the sea mixes with sediments, and can turn into a thick-tar –like mass that destroys the habitat of many bottom-dwelling organisms and valuable spawning site for fauna. Especially vulnerable are slow-moving shellfish such as clams, oysters, and mussels. These creatures can’t escape from oil slick. The tar-like clumps can also drift with tides and currents and pile up in high seas (3%), or wash up on shores (15%). If a spill occurs near a coastline, beached oil can leak into fresh groundwater resevoirs that often extebd beachesn contaminating local wells (…).
In many spills involving tankers or offshore oil wells, some of the oil spilled initially catches fire, resulting in atmospheric emissions of gases that contribute to global warming anda cid rain, as well as large quantities of toxic ash. The fate of sludges is more complex to determine, since synthetic oil has a longer life span in the natural environment, accumulates in the food chain and contains toxics such as dioxins and haevy metal that have dramatic effects on wildlife.
Oil can harm the marine environment in three diffrent ways : by poisoning after ingestion, by direct contact and by destroying habitats. Its impacts are deadlier on coasts than in open ocean, as more living organisms are affected. Marine mammals and birds can ingest a great deal of oil while attempting to clean themselves. Carnivorous animals and birds which eat the carcasses of other oiled creatures also end up ingesting potential toxic amounts. Birds and marine mammals can also be killed by direct exposure to oil (…). It can cover a bird’s feathers, making it impossible for it to fly, and so heavy it may simply sink rather than float. Oil also eliminates the ability of a bird’s feathers and mammals’ fur to keep them warm, leading to death by hypothermia (…).
Fish ingest large amounts of oil through their gills. If this does not kill them directly, it can inhibit their ability to reproduce, cause deterioration in their DNA and result in offspring which are deformed. Fis hand shellfish metabolism often degrades oil components into other substances even more toxic for them.
What can be done ?
Powerful tools are available under international conventions ti better control or avoid marine pollution from oil (…). The ultimate goal of the 1973 Convention for Prevention of Pollution from Ships and the related 19768 Protocol (MARPOL) is the « complete elimination of intentional pollution of the marine environment by oil ond other harmful substances ».
Under the 1992 amendments to MARPOL, vessels may discharge oil into the ocean at a rate of 30 liters per nautical mile (16 liters per km), as long as they are further than 80 km from shore. The evidence suggests that it is common practice for vessels to exceed this limit. The protocol also introduced the concept known as a protective location of Segragated Ballast Tanks (SBT). SBT’s are empty on the cargo-carrying leg of the voyage and only loaded with water ballast for the return leg. Ballast water then doesn ‘t mix with foul slop or sludges as it is contained in these specific tanks. Ships with SBT are so likely to result in smaller oil spills in case of accidents, as the oil is contained in smaller multiple tanks, and water SBTs are positioned where the impact of a collision or grounding is likely to be graetest. As such, the amount of cargo spilled after such an accident will be greatly reduced.
In its Annex1, the MARPOL Convention defines Special Areas considered to be so vulnerable to pollution taht discharges from ships within them have been compleetly prohibited : nearly all seas around Europe have been designated Special Areas exept the Norwegian Sea, the Bay of Biscay and the Iberian Coast. The European Community is also urging marine companies to stop illegal dumping, and often brings to justice the ones that still do. European Directive 2000/59 calls for harbours to have a proper waste collecting facility. Including waste collection cost directly in harbour taxes (package price) is being tried in Sweden and Germany, resulting in much lower illegal discharges in the North Sea. The EC is also reinforcing aerial and sattelite observation, ARGOS markers and widespread use of « black boxes », as well as an appropriate legal system with trained inspectors and judges. It is in the process of harmonising financial sanctions among member states. Today they vary by a factor of 30, leaving the ship a choice where to discharge depending on the risk.
On the national level, it remains very difficult to carry out effective sanctions, other than against illegal actions that take place in national waters and specific protected areas. Coastal states have limited jurisdiction over passing ships flagged by other sttes. Beyond territorial waters and the Exclusive Economic Zones (EEZ, or similar areas), the role of coastal states is restricted to monitoring and collecting « sufficient evidence » of pollution offences, for reporting to the administrative state of the culprit ship (flag state). While the flag states are bound by international law to investigate such reports and punish polluters, what constitutes « sufficient evidence » is their own decision. Thus, the vast number of pollution incidents takes place just beyond territorial waters and the EEZ (…).
The most effective method for reducing the amount of oil in our seas would be to use less oil. As long as oil remains our primary energy source, hydrocarbon pollution from illegal discharge and accidents and their impacts on marine and coastal biodiversity will continue to occur. Crude oil provides about 40% of all present global energy demand, the largest single energy source. Oil exploration is projected to grow by another 60% in the next 30 years, while keeping a high share of world energy use (…).
Oil is used in power plants and for heating in some countries ; however, the main consumer of oil products is the transport sector. Increased energy efficiency and renewable forms of energy such as solar and wind are ckean alternatives that could reduce our dependence on oil.
Environment Alert Bulletin