Trans Carrier

On 23 February 2020, the Trans Carrier was en route from Rotterdam (Netherlands) to Stavanger (Norway) when it was caught in a heavy storm off the Danish coast, resulting in damage to a container carrying polypropylene pellets. In total, 13.2 tonnes of plastic pellets, out of the 26 tonnes transported by the Trans Carrier at the time of the incident, were released into the North Sea.

The spill contaminated the Oslo Fjord and the west coast of Sweden, affecting around 700 coastal sites (Kystverket, 2020).

The crew reported the incident directly to the Norwegian authorities but initially indicated a limited spill. No response operations were therefore organised at sea.

Deposits of plastic pellets in coastal areas were observed from mid-March 2020 in the Oslo Fjord, some 3 weeks after the incident occurred. The Norwegian authorities carried out modelling of the ocean currents to identify other potential areas of deposits.

Clean-up operations by the local authorities and volunteers started in March 2020 after large quantities of plastic pellets were found on 16 March in Fredrikstad (Norway). On 7 May 2020, a national response operation was launched by the Norwegian Coastal Administration (NCA) because of the size of the area to be covered and the number of affected sites. Initially, the NCA and inter-municipal committees organised shoreline surveys to identify areas of deposits and accumulation. This highlighted the major influence of currents and winds on the trajectories of the plastic pellets, which is consistent with the low density of polypropylene, causing the pellets to float.

During the clean-up operations carried out from March 2020 onwards, various techniques were tested and evaluated in areas with different geomorphological profiles. In total, four types of techniques were tested in nine different habitats: manual collection, sieving, collection using portable vacuum cleaners and suction vehicles, and separation in water baths using the difference in density between the plastic pellets, seawater and sand. To effectively monitor the clean-up operations, the NCA used a colour code to track progress at the various sites.

The NCA applied a rule of thumb to determine the clean-up endpoints at each site: if the quantity of plastic pellets collected manually was less than 0.5 litres per person per day, the clean-up work was stopped. Of the 13.2 tonnes of pellets spilled, the Norwegians managed to collect around 4.4 tonnes, through 10,000 hours of work by the operators involved.

To the best of our knowledge, no information on the management of the plastic pellets collected during clean-up operations is currently available.

Environmental surveys were performed on birds and fish to identify potential impacts. Around fifty eider ducks were investigated by the Norwegian Institute for Nature Research (NINA) while the Institute of Marine Research investigated the stomach contents of more than 600 fish (9 different coastal species). No correlation was found between the presence of plastic pellets and the increased winter mortality rate among eider ducks in the Oslo Fjord (plastic pellets were only found in 2 ducks out of 50 investigated), while no ingestion of plastic pellets was observed in fish. The scientists therefore concluded that there was no impact on birds or fish.

Lessons learnt and recommendations

• The NCA recommends initially checking for plastic pellets at spots along the coastline where litter is known to accumulate and which are likely to be the most severely affected by large quantities of plastic pellets if they reach the coast. Such prior surveys are essential in order to prioritise sites for clean-up operations.
• The NCA noted that when the plastic pellets were washed up on the beaches, they tended to accumulate in the top 15 cm of sediment, initially forming an uneven belt along the beach.
• Windy conditions can cause plastic pellets to be moved quickly and easily (due to their low specific gravity) far beyond the beach and into the vegetation. Vegetation tends to trap plastic pellets and limits the distance travelled. On the other hand, heavy rain tends to move plastic pellets down towards the sea, where they can be remobilised then washed up at another site. In this context, according to weather conditions and the morphology of the coastline, rapid response operations may be required to avoid a significant increase in clean-up times. The NCA recommends starting shoreline clean-up operations as quickly as possible after the survey phase. Weather conditions also affect the clean-up process, which is most effective in dry, warm weather (dry sediment and soil are easier to clean). However, during winter, the reduced biomass of vegetation can facilitate the recovery of plastic pellets in certain environments that are difficult to access/clean without risking causing damage to the ecosystems (e.g. coastal meadows).
• The NCA notes that appearances can be deceptive and it is important to carefully assess the level of contamination during the initial inspection. Large deposits do not necessarily require lengthy clean-up operations, and conversely, areas that appear to have a low level of contamination may be heavily contaminated, particularly when the plastic pellets are in among vegetation or rocky areas, making recovery more complex.
• The NCA also concluded that it would not be possible to remove all the plastic pellets spilled.