Urban runoff carries a variety of compounds many of which are largely unknown organic pollutants occurring in low concentrations. This study combines analyses targeting known contaminants (metals, phthalates and nonylphenols, octylphenols and their ethoxylates) with effect-based methods that indicate the mixture effects of known and unknown substances. The potential chemical hazard of roof runoff was investigated during a rain event sampled in June in Luleå, northern Sweden. The investigation included measures of oxidative stress response, aryl hydrocarbon (AhR) activation, and endocrine disruption (androgenic, antiandrogenic and estrogenic effects) of the dissolved and the particulate phases in the water. In the runoff, significant metal release from copper (5320 μg Cu/L), zinc (8690 μg Zn/L) and galvanized roofs (8050 μg Zn/L) was observed, whereas for organic compounds only DINP (280 μg/L) and DEHP (1.8 μg/L) were detected from one of the PVC roofs. Results on biological effects showed cytotoxic interference for most samples and genotoxicity for all samples. For each assay, specific effects were detected in ≥50 % of the samples except for androgenic activity. Most commonly, oxidative stress and AhR activity were observed. For oxidative stress, the range of BEQ concentrations was <14–131 μg/L tBHQeq (dissolved phase) and 9.04–50.8 μg/L tBHQeq (particulate phase). For AhR activity, the range was <0.427–5.8 ng/L TCDDeq (dissolved phase) and 0.383–23.5 ng/L TCDDeq (particulate phase). Particles accounted for a high share of activity in runoff for the AhR assay (>70 % for majority of samples), whereas for the other assays the share was more variable. Results of this study suggest that chemicals present in the roof runoff may cause biological effects that are higher compared to drinking water samples and in similar ranges to those previously reported for stormwater from larger catchments for oxidative stress and AhR activity.

A curtained stormwater storage and treatment facility was constructed in Lake Storsjön (Sweden) to treat urban stormwater runoff discharges. Over two and a half years, sediments were sampled four times across four facility zones (from inlet to outlet) in two depths to inform facility operation and polluted sediment management. Sediments were analysed for particle size distribution, metals, polycyclic aromatic hydrocarbons, and organic matter content to assess the spatial distribution of deposited sediment characteristics. Finer sediments (<0.016 mm) prevailed near the outlet, with a higher presence of fine particles in the deeper layer (10–20 cm). Substantial variations in chemical concentrations were observed, differing by up to three orders of magnitude. Higher concentrations were consistently found in the inlet zone and deeper layers (10–20 cm depth) throughout the sampling program. Combined horizontal and vertical distributions of sediment characteristics indicated a predominance of historical deposits in the sediments collected. Frequent exceedances of Predicted No-Effect Concentrations of chemicals, particularly in the inlet zone, highlighted potential risks to the aquatic environment that would result from dredging activities. This underscores the importance of considering broad mitigation strategies, including the capping of contaminated sediment, to control the environmental impacts of contaminated sediments on the lake ecosystem.

Urbant dagvatten transporterar ett stort antal organiska ämnen från många olika källor i stadsmiljön. På senare tidhar effektbaserade analyser utvecklats för att komplettera kemiska analyser och karakterisera biologiska effekter avkemiska blandningar. Denna rapport syftar till att öka kunskapen om olika typer av dagvatten kan orsaka oxidativstress (Nrf2), aktivera arylhydrokarbonreceptorn (AhR), östrogenreceptorn (ER), androgenreceptor antagonism(Anti-AR) och agonism (AR), samt genotoxicitet. Proverna bestod av (i) avrinning från åtta vanligt förekommandetak/byggnadsmaterial samt (ii) dagvatten från tre urbana avrinningsområden med olika markanvändning. Resultatenvisade att de vanligaste effekterna för båda typerna av vatten var AhR-aktivitet. För proverna från takavrinninganalyserades löst och partikulär fas var för sig och den partikulära fasen stod för en stor andel av den totala effektenav AhR-aktivitet (>70 %) i proverna. Den högsta toxiciteten observerades i avrinning från bitumenbaserad takpapp,takdukar av PVC samt metallplåtar av koppar, zink, och korrugerad och belagd stålplåt. Takavrinningsproverna ochdagvattenproverna från hela avrinningsområden uppvisade liknande nivåer för oxidativ stress och Anti-AR, medanprover från hela avrinningsområden uppvisade betydligt högre BEQ- koncentrationer för AhR och ER.

Fortsatt urbanisering leder till ökning av ogenomsläppliga ytor samt intensifiering av antropogena aktiviteter,vilket leder till ett behov av noggrann planering för att minska den negativa påverkan på det naturligavattenkretsloppet och recipienterna. I ideala fall börjar detta med att minska föroreningars spridning tilldagvatten, exempelvis genom att använda material som släpper ifrån sig mindre föroreningar (Müller etal., 2023), eller genom gatusopning (Sansalone and Ying, 2008). Det omarbetade EU direktivet om reningav avloppsvatten (Directive (EU) 2024/3019) understryker dessutom vikten av att behandla förorenat dagvattenmer lokalt, exempelvis genom blå-grön infrastruktur (BGI), också kallat naturbaserade lösningar.Samtidigt måste det begränsade utrymmet i stadsområden som är tillgängligt för grönområden användaseffektivt, med hänsyn till multifunktionalitet (Nilsson et al., 2022). BGI används inte bara för dagvatteninfiltrationutan även för förbättring av livskvalitet, rekreationsvärden, estetik, biodiversitet (Taguchi et al.,2020).Vid planeringen av subarktiska städer tillkommer ytterligare en utmaning, i form av långa vintrar och betydandemängder snö. Detta ställer krav på effektiv snöröjning och hantering av snösmältningen. Vanligenär det inte möjligt att lagra all snö i staden, särskilt i täta och centrala områden. Därför transporteras enstor del av snön till centraliserade snötippar, medan snön i bostadsområden lagras på mer lokala snöuppläggningsplatser.Det är till exempel vanligt att snö lagras i diken i anslutning till vägar och parkeringsplatser,en lösning som möjliggör snabb snöröjning och bibehållande av säkra körförhållanden under helavintern. Diken kan därför ses som multifunktionella ytor, där anläggningar för dagvattenhantering kombinerasmed snöhantering (Gavrić et al., 2021; Öhrn Sagrelius et al., 2022). Det behövs dock mer kunskapkring hur snölagring påverkar dikens dagvattenhantering.

Urban stormwater typically enters sewer networks through gully pots, which allow a primary sedimentation of solids upstream of the piped network. The regular removal and disposal of retained sediment are necessary, costly and can involve environmental risks due to the contamination of sediments with substances from the urban environment such as metals. The concentrations and speciation of Cd, Cr, Cu, Ni, Pb and Zn were analysed in sediments from 26 gully pots located in different land use areas in Stockholm, Sweden. In addition, accumulation rates of both sediment and metal masses were evaluated, providing a basis for optimising maintenance practices and better understanding of impacts of characteristic urban land use types. Metal concentrations varied by at most a factor of eight between samples and were always below Swedish polluted site guidelines for less sensitive land use, with only eight samples exceeding the guideline values for Cu and Zn for sensitive land use. Sequential extraction showed Pb and Zn to be the most mobile metals. Sediment accumulation rates varied from 0.003 to 0.197 kg/m2 impermeable surface/year. Metal accumulation rates were much more variable than metal concentrations, with a factor of up to 172 between the highest and lowest rates and the highest metal accumulation rates corresponding to the lower range of mass loads in road runoff. Differences in metal concentrations, sediment or metal mass accumulations could not be solely attributed to either traffic or catchment land use. In contrast, traction grit used for winter road maintenance, which has low (but detectable) metal concentrations, is identified as a major component of gully pot sediments, with a combined effect of both moderating metal concentrations and contributing to total mass.

Detention- and infiltration-based systems for stormwater management trap runoff particles, which gradually form a sediment layer loaded with multiple contaminants. This study examines the trace metal composition of stormwater sediments, through a comparison between French and Swedish infrastructures. Composite sediment samples were collected from 18 infiltration basins in France and 17 wet ponds in Sweden, the catchments of which encompass a diversity of urban and sub-urban contexts. Zinc and copper were consistently more concentrated in sediments than the baseline levels in local soils, while this was not always the case for the other metals in Sweden. Overall, contamination levels were higher in the French sites: median Pb, Cu, and Zn concentrations were respectively 154, 152, and 570 mg/kg in France, and 19, 46, and 178 mg/kg in Sweden. This difference may be due to the functioning of the devices (infiltration vs. detention), but also suggests a possible “dilution” of runoff suspended solids in the Swedish catchments. The latter may originate from crushed traction grit or eroded soil particles, as some of the least polluted Swedish ponds had a relatively high share of permeable surface in their catchments. The geochemical signature of stormwater sediments was also found to be different between the two countries, as illustrated by the different ratios between metals, indicating dissimilarities in emission sources.

Les ouvrages de rétention et d’infiltration des eaux pluviales interceptent les matières en suspension, qui forment progressivement une couche de sédiments poly-contaminés. Cette étude s’intéresse à la composition en métaux traces de ces sédiments, en comparant des infrastructures situées en France et en Suède. Des échantillons composites de sédiments ont été prélevés dans 18 bassins d’infiltration en France et 17 bassins de rétention en Suède, dont les bassins versants représentent une diversité de contextes urbains et péri-urbains. En comparaison du bruit de fond anthropisé des sols environnants, le zinc et le cuivre étaient systématiquement plus concentrés dans les sédiments, mais ce n’était pas toujours le cas pour les autres métaux en Suède. Les niveaux de contamination étaient globalement plus élevés dans les sites français : les teneurs médianes en Pb, Cu, et Zn étaient respectivement de 154, 152, et 570 mg/kg en France, et de 19, 46, et 178 mg/kg en Suède. Cette différence peut s’expliquer par le mode de fonctionnement des bassins (infiltration vs. rétention), mais suggère également une possible « dilution » des matières en suspension sur les bassins versants suédois, due à des graviers de traction broyés ou des particules de sol érodées. Les sédiments des deux pays présentaient une signature géochimique différente, comme l’illustrent les ratios entre métaux, ce qui indique des différences dans les sources d’émissions en France et en Suède.

Three commonly used drainage system components, with considerably different characteristics and roles in stormwater management, were studied and reported on in this thesis: (i) grass swales, (ii) gully pots (GPs), and (iii) stormwater management ponds. With time, solids and associated pollutants accumulate in these components, and regular maintenance is needed to ensure that their design functions, including protection of the environment, are sustained.

Trace metals and their concentrations, loads and speciation were investigated within and among the individual types of components. The study program started with a critical review of processes enhancing the quality of stormwater passing over grass filter strips and through swales, and continued with field research of swale soils, and sediments from GPs and ponds.

The swales studied in the thesis served for stormwater drainage and storage of snow cleared from adjacent trafficked areas during winter months. Results suggest that both stormwater runoff and snow stored in the swale were transport vectors of metals originating from traffic. Other sources of metals were native soils and traction material used in winter road maintenance.

Moreover, the speciation results showed that across components, Zn and Pb were the metals with the highest share in the most mobile fraction, followed by Cu, while Ba, Cr,V, Co, and Ni were found in a higher share in the less mobile fractions.

GP and pond sediments showed similar organic matter content, whereas swales soils showed relatively low organic content, further decreasing with the soil depth. Results suggested that higher organic matter content corresponded to higher concentrations of certain metals in the case of ponds and, to some extent, swales. In the case of GPs, a positive relationship between metals and the proportion of fine particles was detected.

The highest concentrations of Cu and Zn were observed in sediments from ponds and reached 319 and 1380 mg/kg DW, respectively. The highest concentration of Pb (188mg/kg DW) was observed in swale, operating for 57 years located next to a road with the traffic intensity of 11,650 v/day.

The large variation in the accumulated dry mass of solids in GPs (2-91 kg) questions the current practice of emptying all GPs at the same regular intervals. Moreover, of the 26 GP samples, Swedish thresholds for soils with the sensitive (S) land use were exceeded for Cu in five samples and Zn in six samples. Of 32 pond samples, the S threshold was exceeded for Cu in nine samples and Zn in 12 samples; of these, three and eight of the pond samples also exceeded the less sensitive (LS) threshold. Of 96 swale samples, 25 samples exceeded the S threshold for Pb, with one sample also exceeding the LS threshold.

Stormwater ponds are widely used for controlling runoff quality through the sedimentation of particles and associated pollutants. Their maintenance requires regular removal and disposal of accumulated material. This necessitates an assessment of material hazardousness, including potential hazard due to its contamination by metals. Here we analyze 32 stormwater pond sediment samples from 17 facilities using several chemical analysis methods (total extraction, sequential extraction, diffusive gradients in thin-films DGT, and pore water extraction) in order to consider the complementarity and comparability of the different approaches. No clear relationship was found between analyses that have the potential to measure similar metal fractions (DGT and either fraction 1 of the sequential extraction (adsorbed and exchangeable metals and carbonates) or pore water concentrations). Loss on ignition (LOI) had a significant positive correlation with an indicator of the environmental risk developed in this paper (∑ranks) that incorporates different metals, speciations, and environmental endpoints. Large variations in metal levels were observed between ponds. As clustering was limited between the different analyses, a comprehensive analysis of different parameters is still needed to fully understand metal speciation and bioavailability.