PFAS Mass Balance in Three Stockholm Lakes (2022–2023)

This study, commissioned by the City of Stockholm and carried out by Sellén & Filipovic, aimed to quantify PFAS flows and establish mass balances for the lakes Flaten, Magelungen, and Drevviken during the spring melt period of April and May 2023, with comparative data from autumn 2022. The objective was to identify and rank transport pathways and potential sources of PFAS contamination, and to assess seasonal variations in PFAS levels. Sampling was conducted at 16 inflow and outflow points, with flow measurements and chemical analyses performed on 49 PFAS compounds, including ultrashort PFAS such as trifluoroacetic acid (TFA) and perfluoropropionic acid (PFPrA). The study also included TOP (Total Oxidizable Precursor) analysis to detect precursor compounds that may degrade into persistent PFAS. Eurofins performed all analyses and Patrick van Hees and Patrik Karlsson co-authored the report.

The results showed that ultrashort PFAS were present in significantly higher concentrations than short- and long-chain PFAS in all water bodies, with TFA being the dominant compound, often comprising over 90% of the PFAS content measured. In total 20 PFAS were detected and total concentrations ranged from 260 ng/l to 9600 ng/l. PFOS levels exceeded the environmental quality standard (EQS) of 0.65 ng/l in all samples, and PFAS 4 levels surpassed the Swedish drinking water limit of 4 ng/l. While atmospheric deposition contributed minimally to PFOS loads, it was a significant source of ultrashort PFAS. The TOP analysis revealed limited presence of PFAS precursors, with the most notable increases observed in streams flowing into Drevviken.

The study concludes that ultrashort PFAS are widespread and highly mobile, with substantial concentrations in all sampled water bodies. Their presence is linked to both atmospheric deposition and runoff from industrial areas. The mass balance approach proved effective for identifying key sources and transport routes and is recommended for broader application across Stockholm’s remaining water bodies. The report emphasizes the need for further investigations such as detailed studies of Högdalsdiket and Snösätra runoff to support remediation planning, and expanded monitoring of PFAS in sediments and biota.

Link

Report (Stockholm city council; in Swedish)

Questions about PFAS can be answered by our analytical advisory service, which can be reached via the customer support, 010-490 8110 or e-mail: sh-analys.miljo.se@etn.eurofins.com