Per- and polyfluoroalkyl substances (PFAS) are a rising topic in the field of contaminated sites around the world, with destruction of these being an area in dire need of innovation. Previous experiments of destructive character have been proven efficient using boron doped diamond electrodes (BDD) in small scale electrochemical cells. Further need for experimentation on actual site conditions is needed to further evaluate the use of this method, as well as research on alternative electrode materials to reduce the cost of remediation.  In this study, four cells containing contaminated soil were used: one with BDD electrodes, one with iron electrodes and two control cells. The iron electrodes were used to investigate if a less costly electrode material could achieve any degree of PFAS degradation. For the experiment a soil from a previous firefighting training site where firefighting foam containing high amounts of PFAS (620                     g/kg soil concentration) was used. During the first phase of the experiment a constant flow of deionized water was added to the cells containing the soil, and porewater was sampled at the in- and outflow along with the soil porewater, on a weekly basis, to evaluate the distribution of PFAS to provide information about possible degradation taking place. The extent of degradation was not quantified. However, due to differences in the molecular composition of the analysed PFAS a trend where short-chain PFAS increase throughout the experiment in the BDD cell indicated that short-chain PFAS were generated, which is an expected by-product in electrochemical oxidation of PFAS. No short-chain PFAS generation was seen in the iron electrode cell, nor was there a high amount present in the control cell leachate.  Further, leaching of PFAS was more efficient in the control cells, while PFAS in the BDD and iron electrode cell were retained or leaching was slowed down, most likely due to the electrode interaction with PFAS in porewater.Additionally a second phase where water flow through was halted and the cells were run in a batch mode was conducted to see PFAS degradation in stagnant conditions over time. In the stagnant cell in the second phase, only low PFAS concentrations in porewater were recorded while no degradation was established.  Further, fluoride analysis recorded F- concentrations in the range of    M, where the limit of detection was   M, which limited the confirmation of PFAS mineralisation in soil.  From this study insight of the difficulties with soil treatment of PFAS using electrokinetic method was highlighted, with sampling being a key factor in the accuracy of the result. For a more accurate establishment of the degradation experiments in a closed cell, with more extensive sampling throughout the entire column would be necessary. This is needed to generate a clearer picture of changes in PFAS concentration in the soil from the presumed degradation, coupled with a mass balance to provide the fate of PFAS in this type of setup.

Per- och polyfluorerade alkylsubstanser, PFAS, är syntetiska kemikalier som är bioackumulerande, persistenta och toxiska för människor. Dessa ämnen har använts i produkter som textiler, brandsläckarskum, teflon och livsmedelsförpackningar sedan 1930-talet. Avfallsdeponier har länge förvarat olika typer av avfall som innehåller PFAS. Lakvatten från avfallsdeponier är idag en av de största källorna till läckage av PFAS i grundvatten och närliggande vattenkällor. Lakvattnet från Koviks deponi behandlas i en sekventiell biologisk reaktor innan det släpps ut till Östersjön, vilket resulterar i att 83,5 % av utgående vatten består av korta PFAS-kolkedjor, medan resterande 16,5 % av långa kolkedjor. En granskning av historiska data samlad under två år visar att ingen minskning av PFAS över tid erhållits i Koviks lakvatten med den nuvarande behandlingsmetoden, vilket indikerar att den biologiska reningen inte är tillräcklig för att effektivt rena PFAS från lakvatten. För att minska PFAS-utsläpp från lakvatten är PreZeros mål att implementera en metod som effektivt kan separera PFAS med korta kolkedjor från lakvattnet. En jämförelsestudie har utförts av konventionella reningsteknikerna som aktivt kol, skumfraktionering och membrantekniker, inklusive en patenterad teknik kallad Selpaxt, utvecklad av Chromafora. Selpaxt-tekniken från Chromafora, som kombinerar både kemisk och fysisk retention av PFAS med ett ultrafilter, uppvisar en initial avskiljningsgrad på 95%. Denna avskiljningsgrad sjunker dock till 88% efter fem dagars användning. Den minskade avskiljningsgraden beror på återanvändningen av kemikalier i processen. Detta innebär att avskiljningsgraden kan optimeras baserat på ekonomiska överväganden. Tekniken anses lämplig för lakvattnet på Kovik och kan anpassas efter specifika reningskrav. För effektiv avläsning av PFAS i lakvatten från Koviks deponi rekommenderas Chromaforas Selpaxt-teknik. Denna rekommendation baseras på analysresultat från Chromaforas pilotanläggning, i jämförelse med andra reningstekniker och utvärdering av tidigare insamlade data från Kovik. Efter en femdagars rening med Chromaforas teknik visade mätningar att koncentrationen av PFAS minskade från 9583 ng/l till 758 ng/l, vilket motsvarar ett genomsnittligt värde på 92%. Selpaxt-tekniken visar på att vara särskilt fördelaktig för vatten med hög total halt av fasta ämnen och selektiv för korta PFAS-kolkedjor. / Per- and polyfluoroalkyl substances, PFAS, are synthetic chemicals that are bioaccumulative, persistent, and toxic to humans. These substances have been used in products such as textiles, firefighting foam, teflon, and food packaging since the 1930s. Landfills have long stored various types of waste containing PFAS. Leachate from landfills is today one of the largest sources of PFAS leakage into groundwater and nearby water sources. The leachate from Kovik's landfill is treated in a sequential biological reactor before it is released into the Baltic Sea, resulting in 83.5% of the outgoing water consisting of short PFAS carbon chains, while the remaining 16.5% consists of long carbon chains. A review of historical data collected over two years shows that no significant reduction of PFAS over time has been achieved in Kovik's leachate with the current treatment method, indicating that biological treatment is insufficient to effectively clean PFAS from leachate. To reduce PFAS emissions from leachate, PreZero's goal is to implement a method that can effectively separate PFAS with short carbon chains from the leachate. A comparative study has been carried out of conventional purification techniques such as activated carbon, foam fractionation, and membrane techniques, including a patented technique called Selpaxt, developed by Chromafora. Chromafora's Selpaxt technique, which combines both chemical and physical retention of PFAS with an ultrafilter, exhibits an initial separation rate of 95%. However, this separation rate drops to 88% after five days of use. The decreased separation rate is due to the reuse of chemicals in the process. This means that the separation rate can be optimized based on economic considerations. The technique is considered suitable for the leachate at Kovik and can be adjusted according to specific purification requirements. For effective removal of PFAS in leachate from Kovik, Chromafora's Selpaxt technique is recommended. This recommendation is based on analysis results from Chromafora's pilot facility, comparisons with other purification techniques, and an evaluation of previously collected data from Kovik. After a five-day treatment using Chromafora's method, readings showed a drop in PFAS concentration from 9583 ng/l to 758 ng/l, which corresponds to an average value of 92%. The Selpaxt method proves especially beneficial for water with a high total solid content and shows selectivity for short PFAS carbon chains.

The lack of biodegradability of PFAS, or per- and polyfluoroalkyl substances, is due to the presence of many strong carbon-fluorine bonds. Two common PFAS that are found in the environment are perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). This work first studied an innovative pathway for PFAS removal through the adsorption of PFOA and PFOS (pre-concentrating the contaminants) by nanoscale zero-valent iron/reduced graphene oxide (rGO-nZVI) and their subsequent degradation via photocatalysis under UVC light. The GO that was later reduced in nanohybrid production was made utilizing a modified Hummer’s method. The rGO-nZVI nanohybrid was prepared for the first time via thermal reduction at high temperatures. Additionally, the nanohybrid was prepared using the wet chemistry method for comparison. LC/MS/MS analysis was conducted to determine the adsorption efficiencies for PFOA and PFOS using the nanohybrids and their successive removal under UVC light. Chlorinated hydrocarbons are another group of contaminants of concern that should be removed from the subsurface due to their harmful effects. In this study, a more complex mixture of the contaminants including PFAS and chlorinated hydrocarbons was investigated, which is usually found in the superfund and other contaminated sites. Considering the effectiveness of nZVI to remove chlorinated hydrocarbons from the subsurface, engineered nZVI coupled with rGO was utilized to enhance the removal efficiency of the mixture of contaminants, i.e., PFAS comingled with chlorinated hydrocarbons. The synthesized rGO-nZVI nanoparticle showed high adsorption efficiencies for both PFOA and PFOS, i.e., removal of 55.3%, 98.2%, and >99.9% of PFOA of 10, 1, and 0.1 mg/L, and 94.9%, 97.6%, and 85.0% of PFOS of 10, 1, and 0.1 mg/L, respectively, in 3 h. Later degradation of pre-concentrated PFAS under UVC light was also achieved. Using extracted rGO-nZVI, 55.1%, 77.6% of preconcentrated PFOS was degraded starting from 10, and 1 mg/L of initial concentrations before adsorption in the photoreactor at the end of 24 h. In comparison, 68.5% and 47.2% of PFOS and PFOA (starting from 1 mg/L each) was degraded, respectively, using rGO-nZVI directly under UVC light after 24 h. Moreover, it was found that rGO-nZVI had high adsorption capacity of 69.4% and 68.7% respectively for TCE and PFOA in a mixture of these contaminants. Under UVC irradiation, the preconcentrated mixture of TCE and PFOA were both degraded to below the detection limit in 21 h. It was also found that PFOA concentration dropped by 64.3% at 5 h and by 88.7% at 24 h by fresh rGO-nZVI in presence of 10 mg/L TCE. Short-chained PFCAs like PFHpA and PFHxA were found as the intermediates for PFOA degradation using rGO-nZVI under UVC light. Also, under UVC irradiation of a mixture of TCE and PFOA, TCE degradation was supported by the formation of intermediates during the reaction. Because of its composition, photocatalytic activity, large surface area, magnetic properties, and environmental friendliness, the thermal reduced rGO-nZVI particle demonstrated its potential to successfully remove PFAS and comingled chlorinated hydrocarbon from pre-concentration followed by degradation under UVC light. The nanohybrid is promising to be used to repair PFAS-contaminated water bodies.

Syftet med den här studien var att undersöka skummet som bildas på ytan i flockningskammare för kemisk fällning vid dricksvattenberedning i Kommunalförbundet Norrvattens ytvattenverk Görvälnverket. Skummet som bildas sprayas sönder med vatten och följer med vidare i reningsprocessen. För Norrvatten är det intressant att veta om det finns PFAS eller andra miljögifter i skummet för att en eventuell avskiljning av skummet skulle kunna vara aktuellt. Målet var att svara på följande frågor: 1. Under vilka förutsättningar bildas skum i flockningskammare för kemisk fällning på Görvälnverket? 2.Vad skulle det betyda för vattenkvaliteten om skummet avskiljs? 3.Vilka möjligheter finns det för Görvälnverket att avskilja skummet?  Poly- och perfluorerade alkylsubstanser (PFAS) uppdagas på flera ställen i samhället och t ex i dricksvatten hittas förhöjda halter. Det har observerats att PFAS orsakar skada på både djur och människors hälsa. PFAS har en hydrofil (vattenlöslig) och en hydrofob (olöslig i vatten) ände. De egenskaperna gör att de kan agera som ett ytaktivt ämne och förekomma i naturligt eller processrelaterat skum och kan också därför avskiljas med hjälp av t ex skumfraktionering.  Det genomfördes två provtagningar vid olika tillfällen för att mäta halten av PFAS11 och totalt organiskt kol (TOC) i skummet. Två enkäter skickades ut, en till skiftingenjörer på Görvälnverket och den andra till vattenverk i Sverige. En flödesmätning av sprayvattnet utfördes samt en analys av mätdata från Görvälnverket.  Resultatet bekräftade halter av PFAS11 i skummet, 2600 ng/l vid första provtagningstillfället och vid andra 3200 ng/l. TOC-halten vid andra tillfället var 180 mg/l TOC. Enkätsvaren påvisade att det skummar mest på våren i Görvälnverket och att andra ytvattenverk också har skumbildning i flockningskammare. Under ett år går det åt nästan 22 miljoner liter vatten för att spraya sönder skummet som istället skulle kunna distribueras. Dataanalys visade att det finns ett samband mellan TOC och konduktivitet.  Slutsatsen är att avskiljning av skummet skulle ge en förbättrad vattenkvalitet då flotation inte är i bruk. Ett förslag på en sugfunktion presenteras som en möjlig avskiljningsmetod. Vidare undersökning för under vilka förutsättningar det bildas skum behöver utföras. / The aim of this study was to investigate the foam formed on the surface of a flocculation chamber for chemical precipitation, which is a step in the preparation of drinking water in the Norrvatten local federation's surface water plant Görvälnverket. The foam that is formed is removed by spraying with water and hence the material in the foam follows the treatment process. Norrvatten are interested to know whether PFAS or other environmental toxins are present in the foam so that a possible removal of the foam could be considered. The objective was to answer the following questions: 1. Under what conditions is foam formed in flocculation chambers for chemical precipitation at Görvälnverket? 2.What would be the impact on water quality if the foam was removed? 3. What are the possibilities for Görvälnverket to remove the foam?  Poly- and perfluoroalkyl substances (PFAS) are found in many places in society and examples of elevated levels include drinking water. PFAS has been observed to cause harm to both animal and human health. PFAS have a hydrophilic (water-soluble) and a hydrophobic (water-insoluble) end. These properties allow them to act as surfactants and to be present in natural or process-related foam and can therefore also be separated by e.g. foam fractionation.  Two samples were taken at different times to measure the PFAS11 and total organic carbon (TOC) content of the foam. Two surveys were sent out, one to engineers at Görvälnverket and other to waterworks in Sweden. A flow measurement of the spray water was carried out as well as an analysis of the measurement data from Görvälnverket.  The result confirmed levels of PFAS11 in the foam, 2600 ng/l at the first sampling point and 3200 ng/l at the second. The TOC content at the second occasion was 180 mg/l TOC. The survey responses showed that foaming is most common in spring at Görvälnverket and that other surface water plants also have foaming in flocculation chambers. In a year, almost 22 million litres of water are used to spray the foam, which could be distributed instead. Data analysis showed that there is a correlation between TOC and conductivity.  It is concluded that removal of the foam would improve the water quality when the flotation step is not in use. A proposal for a suction feature is presented as a possible removal method. Further investigations on under what conditions foaming is formed needs to be carried out.

Les substances per- et polyfluoroalkylées (PFAS) représentent une large classe de composés chimiques synthétiques produits depuis plus de 60 ans. Les PFAS les plus couramment détectés à travers le monde dans la faune et les humains, le sulfonate de perfluorooctane (PFOS) et le perfluorooctanoate (PFOA), ont été classés comme polluants organiques persistants (POP) et sont responsables de nombreux effets sur la santé. Le PFOS et le PFOA sont inscrits à la convention de Stockholm à l'annexe B et à l'annexe A respectivement à partir de 2009 et 2020. En raison de sa persistance et de son potentiel de bioaccumulation, le PFOS a été progressivement retiré de la production aux États-Unis entre 2000 et 2002, inclus dans la liste « d'élimination virtuelle » au Canada et interdit dans les pays européens. Une fois rejetés dans l'environnement, les PFAS se comportent généralement très différemment de ce que l'on attend habituellement d'un POP. Ces travaux de recherche ont été entrepris afin de documenter les niveaux des PFAS historiques et nouvellement identifiés dans diverses matrices pertinentes pour l’exposition humaines, notamment l'eau potable et diverses espèces de poissons du Canada. Un autre objectif était d’évaluer l'influence de l’effluent d’une station d'épuration des eaux usées municipales sur les signatures isotopiques δ15N et les PFAS de deux poissons du fleuve, le doré jaune (Sander Vitreus) et le doré noir (Sander Canadensis). Ces travaux ont nécessité la mise en œuvre de méthodes d’analyse par chromatographie liquide et spectrométrie de masse à haute résolution. Enfin, une évaluation du risque lié à l’exposition au PFOS/PFOA pour l’environnement et les humains a été conduite. / Abstract: Per- and polyfluoroalkyl substances (PFAS) represent a broad class of synthetic chemicals produced over the past 60 years. The most commonly detected PFASs across the globe in various of wildlife, and humans, perfluorooctane sulfonate (PFOS), and perfluorooctanoate (PFOA), have been classified as persistent organic pollutants (POP), bioaccumulative and causing many health outcomes. PFOS and PFOA are listed to the Stockholm convention in Annex B and Annex A respectively in 2009 and 2020. Due to its persistence and bioaccumulation potential, PFOS was phased out of production in United States during 2000-2002, included in the “virtual elimination” list in Canada, and banned in European countries. Once released to the environment, PFASs generally behave very differently from what is usually expected for a POP. Here, we documented the levels of legacy PFASs and newly identified PFASs in drinking water, as well as in fish species from the Canadian environment. Another research objective was to evaluate the influence of a municipal wastewater treatment plant (WWTP) effluent on the δ15N isotopic signatures and PFAS levels in two fish species, Walleye (Sander vitreus) and Sauger (Sander canadensis). Analyses required the use of liquid chromatography high-resolution mass spectrometry. Finally, a risk assessment of PFOS/PFOA exposure to the environment and humans was conducted. Keywords: Targeted PFAS, suspect PFAS, δ15N, drinking water, fish, biota, environment, AFFF, high resolution mass spectrometry, risk assessment, Canada.

Syftet med detta examensarbete var att validera en metod som kvantitativt bestämmer PFAS ijord, slam och sediment. Valideringen omfattade en del olika tester för att utvärdera metodensrapporteringsgräns, precision, riktighet, mätosäkerhet och specificitet. Excel har använts för attberäkna och sammanställa resultaten från de olika testerna. Blankprover och spikade prover haranalyserats för att undersöka rapporteringsgräns. Kontrollprover har analyserats för attundersöka precision samt specificitet. För att undersöka riktighet har en rad olika tester utförts;ISTD-matchning för några av PFAS-analyter som saknade en direkt ISTD-match, jämförelsermot certifierat referensmaterial, analys av tidigare utförda tester som redan hade analyserats iALS Prag och spikade provmatriser. Mätosäkerheten uppskattade och utvärderades i samrådmed kvalitetsansvarig. Resultatet från metodvalideringen bekräftar att metoden har visat sig vara väl validerad.Samtliga tester som utfördes under valideringsprocessen har konsekvent uppfyllt och överträffatde ställda acceptanskriterium för valideringen. Kriterierna inkluderade bland annat relativstandardavvikelse (RSD), utbyte, bias och halt för olika testparametrar. Den omfattandemetodvalideringen gav starka bevis att metoden är tillförlitlig och kan användas för att genererapålitliga resultat inom PFAS-analys. / The purpose of this thesis was to validate a method for quantitatively determining PFAS in soil,sludge, and sediment. The validation involved a number of different tests to evaluate themethod's reporting limit, precision, accuracy, measurement uncertainty, and specificity. Excelwas used to calculate and summarize the results from the different tests. Blank and spikedsamples were analyzed to investigate the reporting limit. Control samples were analyzed toinvestigate precision and specificity. A variety of tests were performed to investigate accuracy;ISTD matching for some PFAS analytes that lacked a direct ISTD match, comparisons againstcertified reference material, analysis of previously performed tests that had already beenanalyzed at ALS Prague, and spiked sample matrices. The measurement uncertainty wasestimated and evaluated in consultation with the quality manager. The results of the method validation confirm that the method has been shown to be wellvalidated. All tests performed during the validation process have consistently met and exceededthe established acceptance criteria for the validation. Criteria included, among others, relativestandard deviation (RSD), recovery, bias, and concentration for various test parameters. Thecomprehensive method validation provided strong evidence that the method is reliable and canbe used to generate reliable results in PFAS analysis.

Master of Science / Granular activated carbon (GAC) is a treatment technology commonly used in drinking water treatment. Recently, a maximum contaminant limit (MCL) has been proposed for a group of per- and polyfluoroalkyl substances (PFAS), a class of chemicals that have been used in many consumer products and industrial applications. GAC is capable of the treatment of PFAS below the MCL, but in many water sources competing contaminants are present that are also removed by GAC, reducing the capacity for PFAS removal. This requires more frequent replacement of the carbon media and greatly increases the cost of the treatment. Surface modification can be performed to increase the removal capacity and specificity of the GAC, allowing more of its removal capacity to be used for PFAS. Surface modification is performed by coating the GAC in a chemical that is then immobilized on the carbon through electrostatic and hydrophobic interactions. As GAC and many micropollutants treated by GAC, including the regulated PFAS, are negative, performing surface modification using a positive chemical increases the removal capacity of the carbon. Bench-scale tests using fully exhausted carbon showed PFAS removal following up-flow and influent addition surface modification.

Both poly- and perfluoroalkylated substances (PFASs) and mercury (Hg) are persistent bioaccumulative, and toxic substances (PBTs) of great concern due to their health effects on humans.  These pollutants are ubiquitously occurring in the global aquatic environment and dietary intake of fish is the major exposure pathway for humans. PFASs and Hg are widely studied in the temperate zones, but little is known from the tropical aquatic systems in Africa. Lake Tana, Ethiopia, is of high ecological value and predicted to increase its fish production and export during following years, but knowledge of human health effects due to bioaccumulated pollutants loading from this lake is lacking. The objective of this study was therefore to compare Hg and PFAS concentrations between sites and species, evaluate accumulation patterns and assess the human health risk with increased fish consumption.    During October 2014, a total of 97 fish specimens from five species (Labeobarbus megastoma, Labeobarbus gorguari, Labeobarbus intermedius, Oreochromis niloticus and Clarias gariepinus) were collected from seven sites in Lake Tana. The fish was dissected in Bahir Dar, where a muscle sample was taken from the dorsal line, and later analyzed at the Swedish University of Agricultural Sciences. To determine differences and correlations between sites and species as well as for Hg and PFASs, statistical analyses were conducted and to determine the health risks in increased fish consumption a hazard ratio (HR) was calculated for both substances.   The results showed several similarities between Hg and PFASs, including higher concentrations in piscivorous fish species (L. megastoma and L. gorguari) than non-piscivorous and also spatial distribution similarities. Hg concentrations ranged from 0-639 ng g-1 wet weight (ww) with an overall mean of 137 ng g-1 ww for all species. Seven PFASs were detected (PFNA, PFDA, PFUnDA, PFDoDA, PFTeDA, PFBS, PFOS), and the ∑PFSA concentrations ranged from non-detected to 3.61 ng g-1 ww. PFDA was found in all sites and species, compared to PFOS, which only was found in piscivorous species in elevated levels. The positive correlation between Hg and PFOS imply that these substances have similar accumulation patterns. The HRs showed that increased fish consumption is harmless to the Ethiopian population regarding PFAS and Hg contamination. Varied fish consumption is of importance though since several individuals from the piscivorous species contained Hg concentrations exceeding the WHO marketing limit of 0.5 μg g-1 (500 ng g-1). / Både poly- och perfluoralkylerade ämnen (PFASer) och kvicksilver (Hg) är persistenta, bioackumulerande och toxiska (PBT) ämnen som kan utgöra stor hälsorisk för människor. PFASer och Hg förekommer globalt i den akvatiska miljön och den mest betydande källan för mänsklig exponering av dessa ämnen är fiskkonsumtion. Studier av PFASer och Hg är vanligt förekommande i de tempererade zonerna, men väldigt lite är känt från de tropiska akvatiska systemen i Afrika. Lake Tana, Etiopiens största sjö, har stort ekologiskt värde och fiskproduktion och export från sjön förutspås öka under kommande år. Däremot saknas kunskap om hur denna föroreningsbelastning med ökat fiskintag kommer påverka befolkningen i landet. Syftet med denna studie var därför att jämföra Hg- och PFAS-koncentrationer mellan områden och arter, utvärdera ackumuleringsmönster och bedöma hälsoriskerna med ökad fiskkonsumtion i landet.   Under oktober 2014 samlades totalt 97 individer in från fem arter (Labeobarbus megastoma, Labeobarbus gorguari, Labeobarbus intermedius, Oreochromis niloticus och Clarias gariepinus) och från sju olika platser i Lake Tana. Dissektionen utfördes i Bahir Dar (där muskelprover togs från dorsala rygglinjen) och sedan fördes proverna till Sveriges lantbruksuniversitet (SLU) för analys. För att bestämma skillnader och korrelationer mellan områden och arter, samt mellan Hg och olika PFASer, utfördes statistiska analyser och för att utvärdera hälsorisken av en ökad fiskkonsumtion beräknades riskfaktorer för båda ämnena.    Resultaten påvisade flertalet likheter mellan Hg och PFASer, bland annat högre koncentrationer i piskivora fiskarter (L. megastoma and L. gorguari) än icke-piskivora och även likheter i koncentrationer mellan provområdena. Hg-koncentrationerna varierade mellan 0-639 ng g-1 våtvikt (vv), med ett medel på 137 ng g-1 vv för alla arter. Sju PFASer detekterades i analysen (PFNA, PFDA, PFUnDA, PFDoDA, PFTeDA, PFBS, PFOS), där ∑PFSA koncentrationerna varierade mellan icke-detekterbara till 3,6 ng g-1 vv. PFDA förekom i alla arter och områden, medan PFOS bara fanns i förhöjda värden i piskivora arter. Den funna positiva korrelationen mellan PFOS och Hg antyder att dessa ämnen har liknande ackumulationsmönster. De beräknade riskfaktorerna visade att en fiskkonsumtions-ökning inte skulle utgöra en risk för den etiopiska befolkningen med avseende på Hg- och PFAS-halter. En varierad fiskkonsumtion är dock av stor vikt eftersom flertalet individer från de piskivora arterna innehöll högre Hg-koncentrationer än den av WHO rekommenderade gränsen på 0,5 μg g-1 vv.

Per- and polyfluoroalkyl substances, PFASs, are highly fluorinated substances where the carbon chain is fully- or partly fluorinated. A functional group is coupled at the end of the carbon chain which gives PFASs their different properties. PFASs have been used in aqueous film forming foams (AFFFs) to decrease the surface tension of water and form a film on the fuel surfaces. AFFF is one of the main sources of PFASs pollution in the environment. A previous study has shown high PFASs concentrations in surface water in Lake Vänern. This study has analysed PFASs in sediment samples. The main detected PFASs was perfluorooctane sulfonate, PFOS, with concentrations below limit of detection to 51700 pg/g wet weight (ww). The compound detected in the highest concentration in Vissbäcken was PFOS at 7290 pg/g ww, this was followed by 6:2 fluorotelomersulfonate , 6:2FTS, at 516 pg/g ww. In outlet 4 (utlopp 4), PFOS had the highest concentration at 51800 pg/g ww, followed by perfluorohexane sulfonate, PFHxS, at 1790 pg/g ww. The only detected compound in the sediment cores was PFOS with approximately 100 pg/g ww. The high concentration of PFOS might be due to extensive use with subsequent release of firefighting foam in the area and degradation of other PFAS substances into PFOS. / Per-och polyfluoroalkylsubstanser, PFASs, är en grupp högfluorerade ämnen där kolkedjan är helt eller delvis fluorerad. En funktionell grupp kopplas i slutet av kolkedjan vilket ger PFASs dess olika egenskaper. PFAS har använts i vattenhaltiga filmbildande skum (AFFF) för att minska ytspänningen av vatten och bilda en film på bränsleytan. AFFF är en av huvudkällorna för PFAS-föroreningar i miljön. En tidigare studie har visat på höga koncentrationer av PFASs i ytvatten i Vänern. I denna studie har PFASs analyserats i sedimentprover. Den huvudsakliga detekterade PFAS var perfluoroktansulfonat, PFOS, med koncentrationer under detektionsgränsen och till 51700 pg /g våtvikt. Den högst detekterade föreningen i Vissbäcken var PFOS med 7290 pg/g våtvikt, detta följdes av 6:2 fluorotelomersulfonat, 6:2 FTS, med 516 pg/g våtvikt. Den högst detekterade föreningen i utlopp 4 var PFOS med 51800 pg/g våtvikt, följt av perfluorhexansulfonat, PFHxS, med 1790 pg /g våtvikt. Den enda detekterade föreningen i sedimentpropparna var PFOS med ungefär 100 pg/g våtvikt. Förekomsten av PFOS i sediment i sjön Vänern kan bero på omfattande användning med efterföljande utsläpp av brandbekämpningsskum i området och nedbrytning av andra PFAS-substanser till PFOS.

Håbo municipality is looking for alternative drinking water sources for its residence city of Bålsta. One possible source is the Vreta-Bålsta esker located northeast of Bålsta, which could be used for artificial infiltration and extraction of groundwater. Located on this esker is an area called Dragets industrial area, in which several objects of potential contamination have been identified. One of these is a Landfill located in the northern part of the industrial area in which the local fire fighting forces has used this area for training exercises. During these exercises they have used aqueous film forming foams (AFFFs) containing Per- and polyfluoroalkyl substances (PFAS). Some PFASs have demonstrated adverse health effects already at low concentrations and no more than 90ng l-1 is recommended in Swedish drinking water. In order to assess the suitability of the esker as a source for drinking water a model of the esker was created inside the program GMS (Groundwater modeling system). In GMS the package MODFLOW was used to create a groundwater flow model, and the package MT3DMS was used for contamination transport of PFAS from the landfill. The finished model showed a groundwater divide located in the central parts of Dragets industrial area, with the water either running south toward Lake Mälaren or north towards Lilla Ullfjärden. In total three different PFAS species were used in the transport model with the abbreviations PFOS, PFPeA and PFBA. The transport model was created as a point source to see the transport behavior of PFAS from the landfill. This showed that all the contamination transport that occurred would transport the PFAS north towards Lilla Ullfjärden. Based on this result this would mean that a use for artificial infiltration and extraction of groundwater in the southern part of the esker would not pose a contamination risk from the landfill.