Temporal trends and spatial differences of perfluoroalkylated substances in livers of harbor porpoise (Phocoena phocoena) populations from Northern Europe, 1991–2008

Long-term temporal trends (1991–2008) and spatial differences of perfluoroalkylated substances (PFASs) were investigated in harbor porpoise (Phocoena phocoena) liver samples of juvenile females from the Baltic and North Sea. Additionally, spatial differences between the populations in the Baltic Sea and Atlantic Ocean (i.e. Iceland and Norway) and the influence of the body mass, age and sex on the PFAS concentrations were examined. Perfluorooctane sulfonate (PFOS) was the predominant compound with a concentration range of 160–2425 ng/g wet weight (ww), followed by perfluorooctane sulfonamide (PFOSA, 1–237 ng/g ww) and perfluoroundecanoate (PFUnA, 3–124 ng/g ww). In terms of temporal trends, perfluoroalkyl sulfonates (PFSAs) and PFOSA concentrations decreased over time, while, conversely, the C9–C13 perfluoroalkyl carboxylate (PFCA) concentrations increased. Spatial distribution of the contaminant concentrations showed consistently higher concentrations in the Baltic Sea and lowest concentrations in the Icelandic population of the Atlantic Ocean.

► Statistically significant temporal trends for eight of ten detected PFASs.
► Higher concentration levels in the Baltic Sea than in the North Sea.
► Decreasing temporal trends for PFHxS, PFHpS, ΣPFOS and PFOSA.
► Increasing temporal trends for PFCAs.
► Spatial differences: Baltic Sea > Norwegian Atlantic Ocean > Icelandic Atlantic Ocean.