Natural breakdown of pollution

The seas and oceans of the world do an excellent job of storing and in many cases destroying the pollutants that the industrialised world want to get rid off. Some seas are better at this job than others and some pollutants are more easily destroyed than others. A vegetable oil spill in the middle of the North Atlantic in January will generally have a short life expecancy as the actions of wind, wave, and bacteria attack the slick. The same cannot be said for other types of pollution such as plastics which in many environments can persist for centuries. Similarly, some areas of the world are not as well suited to the job of waste repository as others. In particular the Mediterranean, a semi-enclosed basin with little flushin, is one of the seas least able to break down oil, sewerage, and chemical pollutants pumped daily into its waters. Yet it is one of the most actively polluted.
 

Intentional, accidental, and natural oil spill

The main sources of marine oil pollution are (intentional and accidental) releases from ships, natural slicks and pollution from land. The first source is the most important. Hydrocarbons are vital to the economies of all the nations of the world and for the vast majority, these fuels must be transported across great distances by sea before they can be used. Inevitably not all of the estimated 100.000.000 tonnes of oil loaded into tankers every day in the North Sea, the Middle East or any of the other oil production areas ends up being delivered to the consumer at the other end. Some is lost in large dramatic spills such as that from Sea Empress on the South Wales coastline which has the immediate effect of killing waterfowl, mammals and other sea life while also inflicting more insidious harm in the form of long term disruption and pollution of the food chain long after the clean-up operations neeeded to remove the cosmetic damage. These dramatic and news-worthy accidents are a disaster for the local environment but may represent just a quarter of the total input of oil from ships into the oceans each year. For exmaple, of the 200.000 tonnes that a tanker might carry, 700 tonnes will remain stuck to the sides of the storage tanks after delivery of the oil. This oil must be disposed of before the next load can be taken on board and one of the easiest and cheapest ways of doing this is simply to dump it at sea on the return journey.
 

Marine oil pollution: a threat to the environment

Oil is an extremely toxic substance, containing between 100 and 200 known carcinogens in every 5 tonnes released into the oceans. A significant proportion of all oil dumped in the sea is to be found in the Mediterranean despite the fact that since 1983 it has beeen illegal to dump oil in the Medidterranean. It is evident, that such dumping is still widespread, inflicting a heavy cost on a delicate environment as well as damaging the tourist and fishing industries.

In fact, oil spills can cause substantial damage to the environment. In general, spills belong to two main categories: oil spills due to accidents, and illegal oil releases from platforms or ships, for instance from flushing of the ships tanks. Although the amount of oil involved in each spill usually is small, a large total number of spills occurs. The amount of oil spill from rinsing of tankers and "natural" losses in the Mediterranean alone is estimated to 600.00 tonnes yearly (threee times the Amoco-Cadiz pollution). Early warning of oil spills can help reduce the damages to the environment by identifying the amount of clean-up possibly needed.
 

Environmental status of the Mediterranean

The Mediterranean Sea is a well frequented sea route allowing access to Southern Europe, North Aftica, The Middle East and The Black Sea. The result of this extensive marine traffic is a high risk of oil pollution, both intentional and accidental. In addition to the obvious ecological risks associated with such pollution in a closed sea area, it is in the interest of all nations bordering the Mediterranean to protect their coastal zones on which they depend for tourism and other human activities.

There are two imporant economical activities that can be affected by oil pollution and which would benefit from any measure taken in the direction of oil spill monitoring and detection: tourism and fishing. The quantification of a benefit analysis is rahter difficult, therefore only a qualitative analysis is given below:

• Tourism

Tourism can be considered as the most imporant Mediterranean industry, and the majority of the tourism activities are based on coastal resources. The negative effects that oil spills can have on tourism are obvoius. In this case, the main concern is focused onto the arrrival of the pollution to the vicinity of the seaside.
 

• Fishing

Fishing is a traditional economic activity in the Mediterranean. Although most of the captures are done from the coast, coastal fishing is not to be forgotten. Furthermore, the importance of fish farming is steadily increasing. These two latter activites can be sereously affected by the presence of oil pollution.

The deliberate dumping of oil in the Mediterranean is illegal. It is estimated that around 330.000 tonnes of oil are deliberately and illegally dumped in the Mediterranean Coastal zone each year. Other figures indicate that there may be as much as 1.000.000 tonnes dumped each year, perhaps demonstrating that too little is known about the full extent of the pollution problem in the Mediterranean, a problem that Earth Observation may be in a position to solve.
 

ENVISYS - a solution to the problem of marine oil spills

It is a challenge to combine all the information required. It may be necessary to add ancillary data, like meteorological data, to do a proper assessment of the situation. The technology for this is present through the application of Internet and Internet-accessible databases. There are still bureaucratic obstacles, like data policy and data pricing that may slow the development within this area. Data must be combined and presented in an optimal way to make the user able to make the right decisions. A wrong decision may be fatal, so this is crucial. A combination of Geographical Information System (GIS) tools, ordinary database tools and an efficient Graphical User Interface (GUI) makes this possible. The ENVISYS project demonstrates a solution for emergency detection, monitoring and management utilising the above mentioned technologies. The system automatically transfers satellite data as they are available from the ground station to the monitoring centre. The data are analysed automatically and immediately, and the attention of the operator is called if a suspicious situation is detected in the satellite data. Satellite images, map data, wind data and sea current data are merged together using GIS, RDBMS and GUI technology in order to support the operator and users to make the right decisions. One is also supported with oil spill development simulators and a database of cleanup equipment to make appropriate decisions.