Per and polyfluoroalkyl substances (PFAS) are found ubiquitously in the environment across the globe.These substances have high persistence due to the strong carbon and fluorine bond. In the aquaticenvironment, due to high persistence, these substances don’t decay easily and are detected on the surfaceas well as in groundwater sources. Human exposure to PFAS has been observed due to ingestion of PFAScontaminated food and water which has an adverse effect on the human health. High concentrations ofPerfluoroalkyl Octanoic Sulphonate (PFOS) and Perfluoroalkyl Hexanoic Sulphonate (PFHxS) wereobserved in Lake Ekoln. The main aim of this study was to analyze the spread of PFOS and PFHxS in thelake. Hydrodynamic modelling of flow and water quality modelling in the lake was performed usingMIKE 3 FM software for the evaluation of the spread pattern of PFOS and PFHxS in the lake. Twoscenarios with the different mass fluxes of PFOS and PFHxS for Fyrisån were assumed for investigatingthe uncertainties and influence of contribution from Fyrisån. Additionally, conductivity from differentinflows was modelled as a passive tracer for understanding the water quality and the circulation in thelake. The results of the simulation showed that Fyrisån and Kungsängsverket are major contributors of PFOSand PFHxS to the lake. Similarly, the analysis of the current spread of PFOS and PFHxS shows that theuncertainty in the model is high and is dependent mainly on the assumption of mass flux from theFyrisån. Due to the lack of sampling data on the concentration of PFOS and PFHxS, it was difficult to geta reliable assumption for the mass flux from the Fyrisån. From the study, it was identified that thesampled concentration of PFOS and PFHxS also had certain variations which might be due to theinfluence of concentration from different sources and processes. Likewise, the simulation result of PFOSand PFHxS was observed to have a similar pattern of spread. Although PFOS is a long-chain PFAS andPFHxS is a short-chain PFAS and they have different physio-chemical properties, the spread patternswere observed to be similar. As only the hydrodynamic processes were influencing the simulation for thespread of PFOS and PFHxS in the lake and other physiochemical processes such as sedimentation andbioaccumulation were not included in the model, the simulated PFAS results were found similar. To conclude, the study shows that the spread of PFOS and PFHxS is mainly influenced by the flow andconcentration in Fyrisån. Also, higher uncertainty in the model performance was observed due to theissue of reliable mass flux estimation from Fyrisån. Similarly, the influence of processes such assedimentation and bio accumulation are necessary to be included in the model for analysis of spread ofPFAS with different physio-chemical properties.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:uu-478645 |
| Date | January 2022 |
| Creators | Prajapati, Prajwol |
| Publisher | Uppsala universitet, Luft-, vatten- och landskapslära |
| 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 | Degree Project at the Department of Earth Sciences, 1650-6553 ; 552 |
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