Oil spills can be large or small

The most noticeable harmful substance in the marine environment is mineral oil. Once in the water, it forms an easily detectable surface film.

Mineral oils, also known as polycyclic aromatic hydrocarbons (PAHs), are compounds formed in combustion processes and the petroleum industry. Oil is slowly created in nature also. This process is the basis for the world's oil reserves.

Most of the mineral oil discharged into the sea comes from deliberate or accidental discharges on the coast or offshore. Significant amounts of oil are also continuously transported to the sea in the wastewater from humans and industrial plants.

Shipping oil spills can be intentional or accidental

Vessels discharge oil into the sea due to equipment failures, negligence, and by deliberate action. Deliberate oil spills result from discharging the oily residue generated by the operation of machinery or the cleaning of an oil tanker’s tanks into the sea.

Oil emissions are generally low, from a few tens to a few thousand litres. Discharges typically occur on shipping lanes and often offshore.

There has been a marked reduction in intentional oil spills thanks to the increased air surveillance for oil pollution, the introduction of dual-hull oil tankers, as well as an increase in general environmental awareness.

Oil on the shore.

A major ship oil spill is the most significant environmental threat in the Baltic Sea

Oil spills from ships can occur in the event of accidents, while the ship is refuelling or during cargo transfer. Then oil will leak from the vessel into the sea.

Oil can also be spilt into the sea in connection with oil storage depots, damage to tanks and pipelines in oil ports, as well as during ship refuelling and tanker cargo transfers. Every year, dozens of small oil spills occur in ports. In marinas, relatively small amounts of oil are usually discharged into the sea due to boat refuelling problems.

The largest oil spills in the Baltic Sea are the result of maritime shipping accidents. The Baltic Sea, and especially the Gulf of Finland, is one of the busiest sea traffic areas in the world.

Recently, the volume of ship traffic in the Gulf of Finland has grown rapidly, mainly due to an increase in Russian oil transports. This has increased the risk of an oil spill accident. An oil disaster is the single largest environmental threat to the Baltic Sea.

Due to running aground, sinking or collisions, it is most common for a ship's own fuel to spill into the sea. There has not been an actual tanker accident leading to an oil spill in Finnish marine areas since 1987.

Oil spill response at sea.

The future of the Baltic Sea requires risk minimisation

The coastal states of the Baltic Sea, and especially those close to Finland, are well prepared for a potential oil disaster.

The Baltic Sea is a relatively small sea where an oil slick could drift into an archipelago or coastal area within hours or days, depending on the wind. As a result, even the best oil spill response capability cannot completely prevent the effects of an oil disaster on marine nature.

The Baltic Sea is a sensitive marine area where an oil spill accident would spell ecological disaster. It would take decades to recover from such a catastrophe. Furthermore, the social and economic significance of the oil spill in the region would be devastating.

The development of technical safety systems for maritime transport has ensured that the risk of accidents has been reduced, despite the increase in traffic volumes. As safety technology continues to advance, the role of the vessel’s crew will also increase.

Today, most accidents are due to human error. Problems with the choice of routes and communication, as well as incorrect situational assessments, are often the main cause of accidents. It is important to focus on seafarers' skills, working conditions, and coping strategies.

The impact of toxic chemical pollutants in oil spills has been reduced

Both crude and refined oils contain a large number of harmful compounds. The most harmful of these are the polycyclic aromatic hydrocarbons or PAH compounds. They are currently found in water, soil, and living organisms.

Since PAHs are efficient in binding to bottom sediments, the seabed is also a good starting point for measuring these harmful substances. PAH compounds occur in varying concentrations in all marine areas in the surface layers of bottom deposits. In the early 2000s, concentrations were still at a level which caused a significant increase in reproductive disorders, as well as reducing growth in some species of fish.

In the Baltic Sea, deliberate ship oil spills have decreased. At the same time, microbiological activity in the seabed deposits has also changed some of the PAHs to a less dangerous form over time. Thus, the burden and adverse effects of PAHs in the ecosystem have been gradually reduced and are no longer at alarming levels.

If oil discharges into the Baltic Sea remain low and PAH emissions from transport and other combustion processes continue to decline, the risk from these compounds will likely continue to decrease also.