On April 14-15, 2022 a marine spill of hybrid oil (VLSFO) reached the Öckerö and Hönö archipelago. The oil originated from a spill that occurred while the ship Alpine Penelope (Creole Marine Ltd) drew oil from the Swedish bunker ship Fox Luna (BRP Shipping AB) at sea while anchored by the lighthouse Trubaduren outside Gothenburg harbor. The crew estimated the spill to 30-50 L while the Swedish coastguard collected 500 L by the ship and an additional 1000 L of oily water at sea. Single clumps of oil were found as far north as “Ytre Hvaler”, a national park in southern Norway.
Öckerö municipality engaged IVL Swedish Environmental Research institute to 1) investigate the degree of marine pollution caused by the spill, and 2) provide suggestions for mitigation actions and make a follow-up plan for the spill. On May 3, 2022 sediment, invertebrates (snails, Littorina littorea and oysters, Magallana gigas) and macroalgae (Fucus vesiculosus and Fucus serratus) were collected at five oil contaminated (Kröckle, Räveskär, Båteviksholmarna, Norra Öckerö and Saltars) and two reference sites (Halse långe and Tjolmen). Sampling was carried out together with two environmental officers from Öckerö municipality and a representative from ITOPF. All samples, including a water sample from ”Norra Öckerö” and an oil sample collected by the municipal staff during beach cleaning, were analyzed for their contents of aliphatic and aromatic compounds, BTEX, PAHs and alkylated PAHs. Measured concentrations in water, sediment and biota were compared to limit values for individual compounds given in HVMFS 2019:25 based on the EU water framework directive. Measured concentrations in oysters and algae were compared to limit values for seafood for human consumption, provided by the Swedish food agency and the Swedish EPA. Sediments were classified according to SGU guidelines.
Elevated oil pollutant levels were detected in oysters, macroalgae and in seawater surrounding oil polluted algae. The site ”Norra Öckerö” was highly impacted, and both biological and consumption related limit were exceeded for benzo(a)pyrene in biota and bivalves. There are no limit values for PAHs in macroalgae, but by comparing to those developed for biota (bivalves and crustaceans), the environmental limit values were exceeded in algal shoots by a factor 13 for fluoranthene and a factor 132 for benzo(a)pyrene. The limit values for human consumption were also exceeded for benzo(a)pyrene and PAH4 in algae shots from “Norra Öckerö”. At the time of sampling there was thus a serious risk of PAH poisoning from eating oysters or algae (and likely other stationary organisms) collected in the ”Norra Öckerö” area and surroundings.
The sediment samples did not show any pollution related to the oil spill. The elevated levels of fluoranthene and pyrene measured at the reference site “Tjolmen” corresponded to SGU class 3 (moderate pollution). This pollution was likely combustion related, originating from boat or car traffic, and should be further investigated. The water sample from ”Norra Öckerö” contained high levels of phenol, the annual average limit value for benzo(a)pyrene was exceeded by a factor 8 and the maximum limit value for benzo(ghi)perylene was exceeded by a factor 3. Consequently, the water close to the algal belt was toxic. The analyzed oil sample contained high amounts of 2-6 ringed PAHs, which constituted almost 90% of the organic pollutants of the oil. This makes the Öckerö VLSFO oil particularly prone to causing long term effects.Although small, the spill did affect a large part of the coastline. Due to difficulties of coming ashore, all samples could not be collected at all stations. It is likely that biota from the station “Kröckle” contained similar levels of oil pollutants as biota from “Norra Öckerö”, yet samples could not be collected there. Correspondingly, biota from oil polluted areas that were not included in the sampling program likely contained high concentrations of oil pollutants in line with what was found at “Norra Öckerö”. The oil was very sticky and therefore particularly difficult to clean up. The algal belt that extends all along the brim of every island has functioned as an oil filter, collecting the remaining water borne oil, which has then continued to leak water soluble oil components to the coastal waters. In all, the oil spill has led to contamination of biota in many places, with “Norra Öckerö” as the most severely affected site, having negative consequences for marine life and also affecting recreation and collection of food from the sea. Because it has become popular to pick and eat wild algae, and algae farms have been established along the coasts, regulations for safe pollution levels in seaweed and algae should urgently be established by food authorities. The municipality is recommended to consider future oil spills and local pollutions sources, like harbors, roads et c in their coastal planning, especially regarding locations for aquaculture. A follow-up study of the Öckerö VLSFO spill is recommended to further understand the long-term effects on marine life and humans.