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

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