Perfluoroktansulfonsyra och dess derivat (PFOS) har hittats i ökande halter i miljön sedan det började produceras under 40-talet. Syftet med denna studie var att studera PFOS-halten i Igelbäcken i Stockholmsområdet genom att samla in och sammanställa tidigare provdata och att kartlägga föroreningskällor i avrinningsområdet. Halterna befanns vara mycket höga. Den högsta uppmätta halten var 120 ng/l och under perioden 2016-2019 var medelhalten i Slottsallén, i närheten av utloppet, 60 gånger högre än MKN (0,65 ng/l) för inlandsytvatten. Halterna ökar framförallt kring brandövningsplatsen vid Barkarby flygfält, men är fortsatt höga därefter, vilket tyder på att ytterligare källor finns längre nedströms. Ökande vattenstånd och -flöde ger ökad spridning i PFOS-halt. Det finns en positiv, måttlig korrelation mellan vattenstånd och PFOS-halt, vilket skulle kunna bero på högre utlakning. Hela bäckens sträckning bör provtas under samma period för att ge en klarare bild av hur spridningen ser ut. / Perfluorooctane sulfonic acid and its derivatives (PFOS) have been found in increasing levels in the environment since the 40's when it was first produced. The objective of this study was to study PFOS in Igelbäcken in the Stockholm area by compiling previous sampled data and to map pollution sources in the catchment area. The PFOS concentrations were found to be very high. The highest level measured was 120 ng/l and during the period 2016-2019 the mean level in Slottsallén, in the vicinity of the outlet, was 60 times higher than EQS (0.65 ng/l) for inland surface water. The concentrations increases especially around the fire drillsite at Barkarby airfield, but are continuously high thereafter, which indicates additional sources further downstream. Increasing water level and water flow increases the spread in PFOS concentration. There is a positive, moderate correlation between water level and PFOS concentration, which could be due to greater leaching. The entire stretch of the stream should be sampled during the same period to allow a clearer picture of the PFOS distribution.

How we develop our cities not only reflects our priorities and values, but also affect the way we and future generations will experience and learn to communicate with spaces.    To face the fast-changing reality of Anthropocene and find inspiration and strength to face global issues cities have to become not only spaces where we live, work and play, but also places for nature reconnection, ecological education, grounding and inspiration.  Places that could show and tell why it is important to care about our local and global environments, how are they affecting everyday life and how we affect them with our lifestyle.    Igelbäcken kulturreservat gives a great opportunity to explore such topics, as nature and city already have a strong presence in the area. It is a part of the green wedge and has a rich agricultural history. Meanwhile it is also a place of big infrastructural and urban development with 2 big city cores situated closely.   Main aim is to explore how can urban design help in building symbiotic relationships between city and nature and enhance existing landscapes without depleting them, while operating in a very contextually saturated urban environment of Igelbäcken kulturreservat.