Environmental Contaminants in an Urban Fjord, 2024 – Emphasis on Alna River

Summary

This report presents data from the fourth year of a 5-year period of the Urban Fjord programme. The programme started in 2013 and has since been altered/advanced. In 2024 the programme covers sampling and analyses of water, water moss, invertebrates, and trout from Alna River, as well as stormwater from Eastern Oslo City. A sampling campaign was also conducted for source tracing of chlorhexidine, dichloromethane and trichloromethane previously found in Alna River. A total of 240 single compounds/isomers were analyzed, and frequent detection was found of specifc PFAS compounds in aqueous phases, other specifc PFAS compounds in trout liver, UV-compounds and certain QACs in the particulate fraction of stormwater, certain benzothiazoles in stormwater (dissolved and/or particulate fraction) , chlorinated paraffns (MCCP and LCCP) in biota, certain siloxanes in nearly all matrices, metals in all matrices, and PCBs in biota. Biomagnifcation was only observed for a couple of the PCB congeners. However, as expected, biomagnifcation was observed for mercury and PFOS. Biomagnifcation of silver was observed when trout was represented by liver samples, but not muscle samples. The source tracing showed the presence of the compounds at several stations