Investigations were performed to find out how PFAS have been spread in Tyrifjorden and the food chain, consider sediment sources, and the levels in fish and biota.
All field work for the Norwegian Environment Agency and the PhD has been completed. The different sampled media are sediment, sediment cores, sediment traps, pore water, surface water, biota from different trophic levels, and passive samplers (POCIS). Performed field work in Tyrifjorden is summarized below.
Number of samples of the different media
Number of samples
Lake and river surface water
Passive sampler (POCIS)
June 2019 Tyrifjorden
Follow up field work was carried out in June 2019 to assess whether the POCIS passive sampler is suitable to determine bioavailable water concentrations. The passive samplers were developed and used in collaboration with NIVA and were deployed for 2 weeks at Viul, the Storøya area and the Nordfjorden area. The samples were analyzed in September 2019.
August 21 – August 24 2018: Viul (Tyrifjorden)
Most of the fishing carried out for the Tyrifjorden case study was done so by local fishing enthusiasts, however sampling of fish, sediments, and water in Randselva (downstream the factory area at Viul) was carried out by NGI.
Pike and perch were sampled, as planned. PFAS profiles and concentrations in these individuals were compared to those caught in the Tyrifjorden lake to assess PFAS sources.
Summer 2018: Tyrifjorden
Fieldwork started in June 2018. Most sampling of water and sediments was carried out during autumn 2018, however sampling of fish was carried out during summer 2018.
On June 29 NGI had a start-up meeting with the local fishing enthusiasts to discuss sampling stations, methods, and fish species before going with them on the first sampling/fishing trip; a selection of the catch is shown below.