When oil is spilled at sea in Swedish waters, or in the large Swedish lakes Vänern, Vättern and Mälaren, the Swedish Coast Guard is responsible for limiting the spill and tackling it by recovering the oil from the water.

Our task is to prevent, detect and tackle pollution in Swedish waters. We also make sure that oil is dealt with as early and as effectively as possible to minimise the damage.

Our operations are always on standby. We work with other authorities, countries and international organisations so that we are ready to act if a spill occurs.

How the Coast Guard works

When an oil spill occurs, our first task is to locate the spill quickly and assess its extent. In many cases we do this with the help of aerial surveillance. This allows us to quickly map where the oil is and how it is moving.

Next, the response work begins. First we must stop or limit the source of the spill, for example a damaged vessel, and then prevent the oil from spreading further. We do this by placing booms around the oil to keep it within a controlled area.

Once the oil has been contained, recovery begins. It is important to start the work as early as possible, while the oil is still liquid and relatively easy to handle. The more time that passes, the harder it becomes to collect the oil, especially if it emulsifies, sinks or reaches land.

The oil that is recovered is stored temporarily on board our response vessels before it is transported to land. There it is dealt with at special facilities, where it is usually destroyed.

In the case of very large spills or complicated incidents, we can quickly request support from other countries through our international cooperation.

Several factors affect the possibility of tackling a spill

Oil that comes into contact with air and water can go through a number of different processes that change its properties.

One property that affects how oil is handled is viscosity, that is, how thick and slow-flowing the oil is. It varies between different types of oil and is affected by, for example, water and air temperature. A lower temperature gives higher viscosity and a thicker layer, while a higher temperature gives lower viscosity and a thinner layer. When the oil becomes thicker, it is also harder to handle during response work. A lower temperature can also make the oil sink below the water surface or freeze into blocks of ice.

The oil can spread with currents, break up or stick to sediment that then sinks to the bottom. Depending on the type of oil, it can also partly mix with water and form an emulsion, which makes the response work even harder.

When oil spreads in the water, it can quickly cover large areas. Even though the oil is broken down over time by sun, wind and microorganisms, the process can take a very long time, especially in cold seas or sheltered areas with low water exchange. Oils with low density, for example diesel, can easily spread over large areas but evaporate quickly.

Handling an oil spill at sea is difficult, but it is even harder to tackle once it has reached land. It is therefore of the utmost importance to clean up a spill as quickly as possible.

Winter conditions: a special challenge

During the winter months, completely different demands apply. Low temperatures affect both the properties of the oil and our ability to work effectively. When ice forms, the oil can become trapped and difficult to detect. Weather conditions make it harder and limit our ability to use normal equipment, such as booms.

In these situations, other methods are needed. The Coast Guard has access to icebreaking vessels, infrared sensors and other specialist equipment to locate and recover oil under the ice. Our long experience of working in northern waters gives us the knowledge and capacity to handle spills even in difficult winter conditions.

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