Monitoring of environmental contaminants in freshwater food webs (MILFERSK), 2023

This report presents data from the third year of a 5-year period of the MILFERSK program. In 2023 the monitoring program reports on the sampling and analyses of the pelagic food chain in Lake Mjøsa, with the following sample types: zooplankton, Mysis, E. smelt, vendace, and brown trout, in addition to brown trout from Lake Femunden. A total of 205 single compounds/isomers were determined, and frequent detections were found of specific PFAS, PBDEs, Hg and siloxanes through the food chain with biomagnifying properties. Some contaminants, such as octocrylene is found in higher concentrations in the lower trophic levels. A slight downwards trend is observed from 2014 – 2023 for PFOS in Lake Mjøsa. We also observe a lower length adjusted mercury concentration for brown trout in Lake Mjøsa for the period 2014 to 2023, compared to the 9 years prior (2006 – 2014).