Sampling was carried out in order to track the spatial distribution of PFAS pollution in the lake. Water was sampled from the lake and from the river downstream the factory and the fire station. Sediments were sampled in the river up- and downstream the factory, downstream the fire station and from the lake. A sediment core from the lake was dated in order to explore historic PFAS emissions. Fish (perch (Perca fluviatilis), pike (Esox Lucius), whitefish (Coregonus lavaretus), roach (Rutilus rutilus), trout (Salmo trutta), bream (Abramis brama), arctic char (Salvelinus alpinus)) and crayfish (Astacus astacus) were sampled from the river and lake.

Map of Tyrifjorden

PFOS was the only compound detected in lake water. Based on the detected PFAS concentrations and profiles, the factory producing disposable paper products was identified to be the main source of the PFAS pollution. Low concentrations in sediments upstream the factory indicated that there were no significant PFAS sources further upstream. High concentrations observed in sediments sampled downstream the factory and decreasing concentrations with increasing distance into the lake clearly indicated a significant contribution of the PFAS pollution from the factory. The dominant PFAS in lake perch were consistent with those sampled in the river directly downstream the factory, also supporting that the factory is the major source of the observed PFAS in the lake. The results from the dated sediment core indicated two eras of product emissions first from Scotchban and then the FTS dominated product(s), termed the FTS mixture (considered the sum of all FTS and their precursors as well as PFCA after 1990).

Tyrifjord 1 justert web