An isotope analysis using stable water isotope ratios, δ18O and δ2H, paired together with PFAS monitoring has been conducted to achieve a comprehensive understanding of the groundwater origin, transport processes and PFAS contamination dynamics for a portion of the Uppsala Esker affected by artificial infiltration. This information is valuable in developing strategies to meet the water demand that is expected to increase with the growing population, manage and reduce the PFAS contamination and protect the drinking water supply in Uppsala. The foundation of this project is a large set of δ18O and δ2H isotope data stretching back to 2014 until today, provided by Uppsala Vatten, as well as water samples taken between September and November 2023 at six groundwater sampling points in the area around Tunåsen, Uppsala. These six sampling points consisted of four groundwater observation wells, Galgbacken’s wellfield and Tunåsen’s infiltration chamber where water from Fyrisån passes through before being infiltrated in the aquifer. By determining the travel time of the water through the esker from the infiltration point to the wellfield using the stable isotopes δ18O and δ2H the travel time was found to be on average 225 days and the average speed of water at this site was found to be 1·10-4 m s-1. By calculating the percentage of infiltrated surface water from the Tunåsen infiltration chamber in Galgbacken wellfield, a blending ratio could be assessed. This blending ratio was found to be on average 89 % surface water from river Fyris and 11 % virgin groundwater originating from north of the study area. When investigating the PFAS concentration at the six sampling points between Tunåsen and Galgbacken sampling point D showed high concentrations of PFAS indicating that there might be a point source near that sampling point. The PFAS composition did not change drastically along the travel path and not all PFAS comes from infiltration. The isotope analysis can be used as a tool to estimate when a high total PFAS concentration found at Tunåsen is likely to reach Galgbacken, however it cannot be used to draw conclusions about the transport of individual PFAS substances or composition profiles.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:uu-526337 |
| Date | January 2024 |
| Creators | Brännlund, Frida |
| Publisher | SLU, Swedish University of Agricultural Sciences; Department of Aquatic Sciences and Assessment, Division of Environmental Organic Chemistry and Ecotoxicology |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | UPTEC W, 1401-5765 ; 24004 |
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