New report on contaminants in Swedish sea areas
SGU has since 2003 investigated the levels of metals and organic contaminants in sediments on the Swedish sea floor, both in the Baltic Sea and the North Sea. The results, including the latest survey in 2020/2021, are now published in a new report. Among the results are unexpectedly high levels of fluorinated compounds, so called PFASs, in the Gulf of Bothnia.
The levels of PFASs are on average 14 times higher in sediment in the Bothnian Bay and Bothnian Sea compared to other Swedish sea areas (the Baltic Proper and North Sea). The high levels were observed also during the survey in 2014. However, as this was the first time PFASs were analysed within the environmental monitoring of offshore sediment, the results were then considered to be uncertain. As the same pattern appears in the latest survey, the results are now confirmed.
– At present, we do not understand the reason for the high levels in this part of the Baltic Sea, but it must be investigated further, says Sarah Josefsson, project manager at SGU.
Chlorinated paraffins also occur in higher levels in the Gulf of Bothnia. Otherwise, levels of organic contaminants are overall higher in the Baltic Proper than in the northern parts of the Baltic Sea or on the Swedish west coast. The levels of TBT, a biocide previously allowed in boat bottom paint and toxic to benthic animals, have dropped since the monitoring programme started in 2003 but still exceed the environmental quality standard (EQS) for sediments in several locations.
Among the investigated metals, cadmium exceeds its EQS at some monitoring stations in the Baltic Proper during the last survey, while the levels of lead and copper were below their EQS values.
– Cadmium and copper have high levels in sediments in the Baltic Proper because these metals precipitate when there is no oxygen in the sediments, which is the case at deep bottoms in some part of the Baltic Sea, says Sarah Josefsson.
Mercury and lead, on the other hand, occur at higher levels at specific monitoring stations instead of in different sea areas, which indicates that the levels are more affected by point sources.
The environmental monitoring is carried out on behalf of the Swedish Environmental Protection Agency. The Swedish Agency for Marine and Water Management also contributed to the latest sampling in 2020/2021.
Last reviewed 2022-06-29