Per- and polyfluoroalkyl substances (PFAS) are extensively used in urban environments and are, thus, found in urban stormwater. However, the relevance of stormwater as a pathway for PFAS to urban streams is largely unknown. This study evaluated the impact of urban stormwater runoff on PFAS concentrations and spatial distribution in three urban streams affected by stormwater discharges from separate sewer systems. River water was sampled during dry (DW) and wet weather (WW) upstream, immediately downstream, and further downstream of three urbanized areas with separate sewer systems and with and without point sources (i.e. waste water treatment plant, airports). Water samples were analyzed for 34 targeted PFAS compounds and sediment samples for 35 targeted PFAS and 30 PFAS compounds using a total oxidizable precursor assay. The sum of the quantified PFAS concentrations ranged from the reporting limit (RL) to 84.7 ng/L during DW and increased as the streams were affected by WW discharges (0.87 to 102.3 ng/L). The highest PFAS concentrations were found downstream of urban areas and/or point sources (i.e. airports) during WW, indicating a clear contribution from stormwater discharges. A consistent PFAS contribution from the WWTP was observed under both DW and WW conditions. During WW events, concentrations of perfluorooctanesulfonic acid (PFOS) and total PFAS (PFOA equivalents) exceeded the annual average environmental quality standards, which are an established limit of 0.65 ng/L for PFOS and a proposed limit of 4.4 ng/L for total PFAS. Notably, except for the legacy PFAS, PFOS and perfluorooctanoic acid (PFOA), the most frequently quantified PFAS during DW were short-chain. For WW, long-chain perfluorocarboxylic acids (PFCAs) and a precursor, 6:2 Fluorotelomer sulfonic acid (6:2 FTS), were more frequently quantified, suggesting stormwater is a source of these longer-chain and particle-associated PFAS. The detection of unregulated fluorotelomer sulfonates (FTSs) such as 6:2 and 8:2 FTS during WW suggests a need for regulatory action, as these compounds can degrade into more stable PFAS. In sediment, higher concentrations, and a greater variety of PFAS were found at sites with known point sources i.e. airports. Long-chain PFCAs (C7–C13), perfluoroalkyl sulfonates (PFSAs) (C6), and precursors (i.e. N-Ethyl perfluorooctane sulfonamidoacetic acid), were more prevalent in sediments than in the water. Notably, PFOS concentrations in sediment exceeded the lowest Predicted No-Effect Concentration (PNEC) across sites, posing a potential long-term environmental risk, though current PNECs for other PFAS may underestimate such risks. The findings of the study highlight urban stormwater as a source of PFAS to urban streams indicating the need to minimize PFAS sources in the urban environment and to effectively treat stormwater to protect receiving water bodies.

Urbant dagvatten kan innehålla per- och polyfluoralkylämnen (PFAS). Den nuvarande kunskapen omförekomst och transport av PFAS i reningsanläggningar för urbant dagvatten är fortfarande mycketbegränsad. Den här studien utvärderar förekomst, ackumulering och fördelning av 35 PFAS och derasprekursorer i filtermaterial och försedimenteringssteg i tjugo biofilteranläggningar som varit i drift längreän 7 år. C5-14,16 perfluoralkylkarboxylsyror (PFCA), C4,8,10 perfluoralkansulfonsyror (PFSA), metylperfluoroktansulfonamidättiksyra (MeFOSAA, en känd PFSA-prekursor) och okända C6-8 PFCAprekursorer var de vanligast förekommande ackumulerade föreningarna. PFAS och deras prekursoreråterfanns i alla djup i liknande förekomster och koncentrationer. Trots att halterna var något högre i detövre filterlagret och minskande med djup var dessa skillnader i regel inte statistiskt signifikanta. Det fannsingen tydlig skillnad mellan fördelningen av kort- och långkedjiga PFAS, trots att långkedjiga ämnen(PFSAs>C5 och PFCAs>C7) förväntades ha mindre mobilitet på grund av deras högre hydrofobicitet. Deövre 5 cm av biofiltren innehöll ofta de högsta föroreningsnivåerna av PFAS och okända prekursorer,men de fanns också djupare ner i filtret. I motsats till exempelvis metaller och PAHer, räcker det sannolikt inte att endast byta ut det översta filterlagret och/eller sediment på toppen av filtret för att avlägsnamer komplexa och mobila föroreningar som PFAS.

Biocides are incorporated into building surface materials to protect them against algae and fungi growth. When such treated surfaces are exposed to precipitation, they may release these biocides, contaminating receiving water bodies. To regulate the use of biocidal products in line with the European Biocidal Products Regulation it is crucial to identify the precise origin of this type of pollutant. In this study, the leaching of a wide range of biocides and chemical elements from 15 materials was investigated through a laboratory scale experiment. The experimental setup was based on the standard method, SIS-CEN/TS 16637-2:2015. The materials tested included bitumen roofing felt and shingles, impregnated wood, as well as paints intended for concrete, wood, and metal surfaces. Each material was tested in duplicates. All materials were tested at a liquid volume to surface area ratio (L/A) of 22.5 L/m2. Sampling was carried out at three intervals: 6 h, 18 h, and 5 days with the leachant being renewed after each leaching step. The results were that diuron was the most commonly detected biocide from the materials tested. The largest number of biocides, including diuron and its degradation products 1-(3.4-dichlorophenyl) urea (DCPU) and diuron desdimethyl (DCPMU), terbutryn, carbendazim and monuron, were detected in the wood paints. Diuron was detected in all three types of wood paint with a mean areal release ratio of 64.6, 25800, and 5710 μg/m2 for the respective paints. Copper was detected in all leachates from impregnated wood, with mean concentrations of 687, 648, 1450, and 279 μg/L from the four tested wood types, respectively. Some of the biocides released were not reported on the data sheets of the tested materials, indicating a need to investigate broader than only based on the information provided by the manufacturers. Future use of biocides in building surface materials may change due to regulations, phase outs and introduction of new biocides, indicating that source identifications is a continuing effort.

Stormwater is recognised as a vector for microplastics (MPs), including tyre wear particles (TWPs) from land-based sources to receivingwaterbodies. Before reaching the waterbodies, the stormwater may be treated. In this study, sediments from six treatment facilities (fiveretention ponds and a subsurface sedimentation tank) were analysed to understand MP occurrence, concentrations, sizes, polymer typesand distribution between inlet and outlet. The concentrations of MPs showed large variations between and within different facilities withMP concentrations of 1,440–72,209 items/kg (analysed by μFTIR) corresponding to 120–2,950 μg/kg and TWP concentrations from ,DL upto 69,300 μg/kg (analysed by pyrolysis–GC–MS), with significantly higher concentrations at the inlet compared to the outlet. Polypropylene(PP) was the predominant MP type in terms of number in all samples. TWPs were dominant by mass in most (nine) samples. The relativelylow density of PP polymers implies that density might not be the sole factor influencing particle settlement behaviour. Small particlesoccurred more frequently than large ones; around 70% of the particles detected in the samples were 100 μm or smaller. In summary, thisstudy highlights the occurrence of MPs, including TWPs, in stormwater facilities and demonstrates variations in concentrations dependingon sites and locations within the facility.

Stormwater and wastewater floating treatment wetlands (FTWs) can contain plastic floating support systems. However, to date, there has been only one field study into whether a sole FTW was a potential source of microplastics in the environment. In this laboratory study, it was investigated whether floating support systems made from different types of polymers in different FTWs release microplastic when exposed to ultraviolet (UV) radiation. It was found that FTWs made from polyethylene terephthalate (PET; median release of PET=4.6  μg/cm2) released more microplastics than FTWs made from high-density polyethylene (HDPE; median release of HDPE=1.1  μg/cm2). Adding polyurethane (PUR) seems to cause a higher microplastic release from FTWs. Different UV exposures produced no obvious effect on microplastic release from the FTWs. Given the large variation of the data and the limited number of FTW samples, further studies on this topic are recommended.

Den urbana utvecklingen har resulterat i alltmer hårdgjorda ytor och förekomst av konstruerat material i städer, och som följd finns det en stor variation av material som kan bidra till föroreningar till kringliggande miljöer. Dagvatten, såsom regn och smältvatten, har visat sig vara en bidragande faktor till att föroreningar sprids inom urbana områden. Kemikalierna per- och polyfluorerade alkylsubstanser (PFAS) har under det senaste årtiondet hamnat mer i fokus då det framkommit att de är toxiska och svårnedbrytbara i miljön. Trots att dagvatten kan vara en faktor som påverkar spridning av PFAS i urbana områden är det ett forskningsområde med få studier. Denna rapport syftar därför till att öka kunskapen om förekomst av PFAS i dagvattensystem i urbana områden, utifrån ett svenskt perspektiv. 47 prover tagna i dagvattensystem från fyra urbana områden i Östersund under år 2012–2013, analyserades med avseende på 55 olika PFAS-ämnen inklusive beräkningar för summaparametrarna ∑PFAS55 ∑PFAS4, och ∑PFAS24. Proverna bestod av dagvatten från regn och smältvatten samt vissa basflöden tagna i dagvattenledningar. Resultaten visar att i 45 av de 47 proverna förekom minst en av de analyserade PFAS-ämnena. Främst förekommande var PFOS, PFOA, PFNA, 6:2FTS samt PFHpA. Det mest heterogena urbana området, innefattande stora delar av centrala staden och campusområde, hade högst halter av ∑PFAS55 med en median på 144 ng/l i jämförelse med de andra områdena med mediankoncentrationer på 12,6–20,6 ng/l i dagvatten och 4,4–15,1 i basflöden. Resultaten indikerar att PFAS förekommer i urbana dagvattensystem samt att det finns många faktorer i urbana miljöer som bidrar till källor samt spridning av PFAS. 

Stormwater is widely recognized as a pathway for transporting pollutants, including microplastics, from sources in urban environments to receiving waters. Gully pots are often where urban runoff drains into the piped network; they typically include a trap where sediments accumulate. The aim of this work was to contribute to a better understanding of the fate of microplastics as they enter into the urban drainage system, and the role of gully pots in trapping microplastics. Sediment samples collected from 29 gully pots were analysed for non-carbon-black and carbon-black (e.g. tire wear particles) microplastics larger than 40 μm using μ-FTIR and ATR-FTIR, respectively. Commonly found polymers in descending order were PP > EPDM > EVA > PS > SBR, PP was most common both by mass and by number of microplastics. The total concentration of carbon black and non-carbon black microplastics ranged from 709 to 10 600 items/100 g dry matter (DM), (median: 2960 items/100 g). Estimated mass of non-carbon black microplastics ranged from 0.19 to 490 mg/100 g, (median: 3.66 mg/100 g). In total 21 different types of microplastics were detected, the majority of these (13) were carbon black and eight non-carbon black polymer types. By number and the carbon black particles accounted for up to 68% of the microplastics (average 30%), this stress the importance of using analytical methods enabling the detection of both carbon-black and non-carbon black microplastics. Furthermore, the results indicate that gully pots can act as temporary sinks for microplastics, mainly for microplastics larger than 125 μm. The amount of microplastics found in gully pots, together with the very large number of gully pots sited in urban areas, indicates that gully pots can potentially trap large amounts of microplastics, and thus if gully pots are fitted and maintained properly they could significantly contribute to reducing the amount of microplastics reaching receiving waters.