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  • 1.
    Abel, Sebastian
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Eriksson Wiklund, Ann-Kristin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Gorokhova, Elena
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Sobek, Anna
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Chemical Activity-Based Loading of Artificial Sediments with Organic Pollutants for Bioassays: A Proof of Concept2024Ingår i: Environmental Toxicology and Chemistry, ISSN 0730-7268, E-ISSN 1552-8618, Vol. 43, nr 2, s. 279-287Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Persistent organic pollutants (POPs) pose a risk in aquatic environments. In sediment, this risk is frequently evaluated using total or organic carbon-normalized concentrations. However, complex physicochemical sediment characteristics affect POP bioavailability in sediment, making its prediction a challenging task. This task can be addressed using chemical activity, which describes a compound's environmentally effective concentration and can generally be approximated by the degree of saturation for each POP in its matrix. We present a proof of concept to load artificial sediments with POPs to reach a target chemical activity. This approach is envisioned to make laboratory ecotoxicological bioassays more reproducible and reduce the impact of sediment characteristics on the risk assessment. The approach uses a constantly replenished, saturated, aqueous POP solution to equilibrate the organic carbon fraction (e.g., peat) of an artificial sediment, which can be further adjusted to target chemical activities by mixing with clean peat. We demonstrate the applicability of this approach using four polycyclic aromatic hydrocarbons (acenaphthene, fluorene, phenanthrene, and fluoranthene). Within 5 to 17 weeks, the peat slurry reached a chemical equilibrium with the saturated loading solution. We used two different peat batches (subsamples from the same source) to evaluate the approach. Variations in loading kinetics and eventual equilibrium concentrations were evident between the batches, which highlights the impact of even minor disparities in organic carbon properties within two samples of peat originating from the same source. This finding underlines the importance of moving away from sediment risk assessments based on total concentrations. The value of the chemical activity-based loading approach lies in its ability to anticipate similar environmental impacts, even with varying contaminant concentrations. 

  • 2. Abrahamsson, Dimitri
    et al.
    Siddharth, Adi
    Young, Thomas M.
    Sirota, Marina
    Park, June-Soo
    Martin, Jonathan W.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap. Stockholms universitet, Science for Life Laboratory (SciLifeLab).
    Woodruff, Tracey J.
    In Silico Structure Predictions for Non-targeted Analysis: From Physicochemical Properties to Molecular Structures2022Ingår i: Journal of the American Society for Mass Spectrometry, ISSN 1044-0305, E-ISSN 1879-1123, Vol. 33, nr 7, s. 1134-1147Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    While important advances have been made in high-resolution mass spectrometry (HRMS) and its applications in non-targeted analysis (NTA), the number of identified compounds in biological and environmental samples often does not exceed 5% of the detected chemical features. Our aim was to develop a computational pipeline that leverages data from HRMS but also incorporates physicochemical properties (equilibrium partition ratios between organic solvents and water; Ksolvent–water) and can propose molecular structures for detected chemical features. As these physicochemical properties are often sufficiently different across isomers, when put together, they can form a unique profile for each isomer, which we describe as the “physicochemical fingerprint”. In our study, we used a comprehensive database of compounds that have been previously reported in human blood and collected their Ksolvent–water values for 129 partitioning systems. We used RDKit to calculate the number of RDKit fragments and the number of RDKit bits per molecule. We then developed and trained an artificial neural network, which used as an input the physicochemical fingerprint of a chemical feature and predicted the number and types of RDKit fragments and RDKit bits present in that structure. These were then used to search the database and propose chemical structures. The average success rate of predicting the right chemical structure ranged from 60 to 86% for the training set and from 48 to 81% for the testing set. These observations suggest that physicochemical fingerprints can assist in the identification of compounds with NTA and substantially improve the number of identified compounds.

  • 3. Adachi, Kouji
    et al.
    Tobo, Yutaka
    Koike, Makoto
    Pereira Freitas, Gabriel
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Zieger, Paul
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Krejci, Radovan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Composition and mixing state of Arctic aerosol and cloud residual particles from long-term sinale-particle observations at Zeppelin Observatory, Svalbard2022Ingår i: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 22, nr 21, s. 14421-14439Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Arctic region is sensitive to climate change and is warming faster than the global average. Aerosol particles change cloud properties by acting as cloud condensation nuclei and ice-nucleating particles, thus influencing the Arctic climate system. Therefore, understanding the aerosol particle properties in the Arctic is needed to interpret and simulate their influences on climate. In this study, we collected ambient aerosol particles using whole-air and PM10 inlets and residual particles of cloud droplets and ice crystals from Arctic low-level clouds (typically, all-liquid or mixed-phase clouds) using a counterflow virtual impactor inlet at the Zeppelin Observatory near Ny-Ålesund, Svalbard, within a time frame of 4 years. We measured the composition and mixing state of individual fine-mode particles in 239 samples using transmission electron microscopy. On the basis of their composition, the aerosol and cloud residual particles were classified as mineral dust, sea salt, K-bearing, sulfate, and carbonaceous particles. The number fraction of aerosol particles showed seasonal changes, with sulfate dominating in summer and sea salt increasing in winter. There was no measurable difference in the fractions between ambient aerosol and cloud residual particles collected at ambient temperatures above 0 C. On the other hand, cloud residual samples collected at ambient temperatures below 0 C had several times more sea salt and mineral dust particles and fewer sulfates than ambient aerosol samples, suggesting that sea spray and mineral dust particles may influence the formation of cloud particles in Arctic mixed-phase clouds. We also found that 43 % of mineral dust particles from cloud residual samples were mixed with sea salt, whereas only 18 % of mineral dust particles in ambient aerosol samples were mixed with sea salt. This study highlights the variety in aerosol compositions and mixing states that influence or are influenced by aerosol–cloud interactions in Arctic low-level clouds.

  • 4. Adachi, Kouji
    et al.
    Tobo, Yutaka
    Oshima, Naga
    Yoshida, Atsushi
    Ohata, Sho
    Krejci, Radovan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap. Stockholms universitet, Naturvetenskapliga fakulteten, Meteorologiska institutionen (MISU). Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI).
    Massling, Andreas
    Skov, Henrik
    Koike, Makoto
    Composition and mixing state of individual aerosol particles from northeast Greenland and Svalbard in the Arctic during spring 20182023Ingår i: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 314, artikel-id 120083Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Arctic region is warming about four times faster than the rest of the globe, and thus it is important to understand the processes driving climate change in this region. Aerosols are a significant component of the Arctic climate system as they form ice crystals and liquid droplets that control the dynamics of clouds and also directly interact with solar radiation, depending on the compositions and mixing states of individual particles. Here, we report on the characteristics of submicron-sized aerosol particles using transmission electron microscopy obtained at two high Arctic sites, northeast Greenland (Villum Research Station) and Svalbard (Zeppelin Observatory), during spring 2018. The results showed that a dominant compound in the submicron-sized spring aerosols was sulfate, followed by sea salt particles. Both model simulations and observations at the Zeppelin Observatory showed that sea salt particles became more prevalent when low-pressure systems passed by the station. Model simulations indicate that both sampling sites were affected by diffused and diluted long-range transport of anthropogenic aerosols from lower latitudes with negligible influences of biomass burning emissions during the observation period. Overall, the composition of measured aerosol particles from the two Arctic sites was generally similar and showed no apparent variation except for the sea salt fractions. This study shows a general picture of high Arctic aerosol particles influenced by marine sources and diffused long-range transport of anthropogenic sources during the Arctic spring period. These results will contribute to a better knowledge of the aerosol composition and mixing state during the Arctic spring, which helps to understand the contributions of aerosols to the Arctic climate.

  • 5.
    Aguilar-Sanchez, Andrea
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Li, Jing
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Mautner, Andreas
    Jalvo, Blanca
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Pesquet, Edouard
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Mathew, Aji P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Revealing the interaction between nanopolysaccharides and E.Coli by biological studies and atomic force microscopyManuskript (preprint) (Övrigt vetenskapligt)
  • 6.
    Ahlbäck, Malin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Nedskräpning i tätort: En studie om nedskräpning i Tumba och inverkan av nudging2021Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Nedskräpning medför problem för levande organismer och påverkar människors uppfattningar negativt och hur säkra de känner sig i ett område. Syftet med denna studie var att utvärdera nedskräpningssituationen inom tätorten Tumba, Botkyrka kommun, och försöka minska nedskräpning genom att förändra beteende genom att använda ”Nudging” där fotspår målas ut som leder mot papperskorgar inom fem mätpunkter. Tanken var att se om mängden skräp i papperskorgarna ökade och mängden skräp på marken minskade. En statistisk analys av kommunens insamlade data 2018–2020 utfördes och kompletterades av GIS för att identifiera tidsmässiga såväl som rumsliga förändringar inom området. Resultaten tyder på att nedskräpningen minskade med 49% från 2018–2020 (p <0,02) och totalmängden per kvadratmeter var lägre än det nationella genomsnittet. Områden med högre befolkningstäthet var mest nedskräpade trots en högre städfrekvens och nedskräpningen förändrades inte beroende på avstånd till kollektivtrafik eller papperskorgar. Även om den upplevda skräpsituationen förbättrades från 2018–2019 försämrades den 2019–2020 (p <0,01). Skräptyps kompositionen förändrades inte signifikant över perioden men cigarettfimpar var vanligare i Tumba jämfört med nationellt. En viss beteendeförändring kunde mätas. Data om papperskorgs vikt och skräpmängd samlades innan och efter nudging och testades med ett parat t-test. Inom 90% signifikansnivån var nudging effektiv (p = 0,08) med 21% mindre skräpmängd i mätpunkterna och 298% mer skräp i papperskorgarna. Det indikerar att nudging kan vara ett effektivt verktyg för att påverka nedskräpningsbeteenden men metoden var inte lika effektiv mot cigarettfimpar.

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  • 7. Ahn, Seo H.
    et al.
    Yoon, Y. J.
    Choi, T. J.
    Lee, J. Y.
    Kim, Y. P.
    Lee, B. Y.
    Ritter, C.
    Aas, W.
    Krejci, Radovan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Ström, Johan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Tunved, Peter
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Jung, Chang H.
    Relationship between cloud condensation nuclei (CCN) concentration and aerosol optical depth in the Arctic region2021Ingår i: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 267, artikel-id 118748Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To determine the direct and indirect effects of aerosols on climate, it is important to know the spatial and temporal variations in cloud condensation nuclei (CCN) concentrations. Although many types of CCN measurements are available, extensive CCN measurements are challenging because of the complexity and high operating cost, especially in remote areas. As aerosol optical depth (AOD) can be readily observed by remote sensing, many attempts have been made to estimate CCN concentrations from AOD. In this study, the CCN-AOD relationship is parameterized based on CCN ground measurements from the Zeppelin Observatory (78.91 degrees N, 11.89 degrees E, 474 m asl) in the Arctic region. The AOD measurements were obtained from the Ny-Alesund site (78.923 degrees N, 11.928 degrees E) and Modern-Era Retrospective Analysis for Research and Applications, Version 2 reanalysis. Our results show a CCN-AOD correlation with a coefficient of determination R-2 of 0.59. Three additional estimation models for CCN were presented based on the following data: (i) in situ aerosol chemical composition, (ii) in situ aerosol optical properties, and (iii) chemical composition of AOD obtained from reanalysis data. The results from the model using in situ aerosol optical properties reproduced the observed CCN concentration most efficiently, suggesting that the contribution of BC to CCN concentration should be considered along with that of sulfate.

  • 8. Aldabash, Midyan
    et al.
    Bektas Balcik, Filiz
    Glantz, Paul
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Validation of MODIS C6.1 and MERRA-2 AOD Using AERONET Observations: A Comparative Study over Turkey2020Ingår i: Atmosphere, E-ISSN 2073-4433, Vol. 11, nr 9, artikel-id 905Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study validated MODIS (Moderate Resolution Imaging Spectroradiometer) of the National Aeronautics and Space Agency, USA, Aqua and Terra Collection 6.1, and MERRA-2 (Modern-ERA Retrospective Analysis for Research and Application) Version 2 of aerosol optical depth (AOD) at 550 nm against AERONET (Aerosol Robotic Network) ground-based sunphotometer observations over Turkey. AERONET AOD data were collected from three sites during the period between 2013 and 2017. Regression analysis showed that overall, seasonally and daily statistics of MODIS are better than MERRA-2 by the mean of coefficient of determination (R-2), mean absolute error (MAE), and relative root mean square deviation (RMSDrel). MODIS combined Terra/Aqua AOD and MERRA-2 AOD corresponding to morning and noon hours resulted in better results than individual sub datasets. A clear annual cycle in AOD was detected by the three platforms. However, overall, MODIS and MERRA-2 tend to overestimate and underestimate AOD, respectively, in comparison with AERONET. MODIS showed higher efficiency in detecting extreme events than MERRA-2. There was no clear relation found between the accuracy in MODIS/MERRA-2 AOD and surface relative humidity (RH).

  • 9. Ali, Nadeem
    et al.
    Kadi, Mohammad W.
    Ali Albar, Hussain Mohammed Salem
    Rashid, Muhammad Imtiaz
    Chandrasekaran, Sivaraman
    Summan, Ahmed Saleh
    de Wit, Cynthia A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Malarvannan, Govindan
    Semi-Volatile Organic Compounds in Car Dust: A Pilot Study in Jeddah, Saudi Arabia2021Ingår i: International Journal of Environmental Research and Public Health, ISSN 1661-7827, E-ISSN 1660-4601, Vol. 18, nr 9, artikel-id 4803Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    People may spend a significant amount of their daily time in cars and thus be exposed to chemicals present in car dust. Various chemicals are emitted from during car use, contaminating the car dust. In this study, we compiled published and unpublished data on the occurrence of phthalates, flame retardants (FRs), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) in Saudi car dust. Phthalates, a class of chemical commonly used as plasticizers in different car parts, were the major pollutants found in car dust, with a median value of n-ary sumation phthalates 1,279,000 ng/g. Among other chemicals, organophosphate flame retardants (OPFRs) were found to be between 1500-90,500 ng/g, which indicates their use as alternative FRs in the car industry. The daily exposure to Saudi drivers (regular and taxi drivers) was below the respective reference dose (RfD) values of the individual chemicals. However, the estimated incremental lifetime cancer risk (ILCR) values due to chronic exposure to these chemicals was >1 x 10(-5) for taxi drivers for phthalates and PAHs, indicating that the long-term exposure to these chemicals is a cause of concern for drivers who spend considerable time in cars. The study has some limitations, due to the small number of samples, lack of updated RfD values, and missing cancer slope factors for many studied chemicals. Despite these limitations, this study indicates the possible range of exposure to drivers from chemicals in car dust and warrants further extensive studies to confirm these patterns.

  • 10. Aliaga, Diego
    et al.
    Sinclair, Victoria A.
    Andrade, Marcos
    Artaxo, Paulo
    Carbone, Samara
    Kadantsev, Evgeny
    Laj, Paolo
    Wiedensohler, Alfred
    Krejci, Radovan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Bianchi, Federico
    Identifying source regions of air masses sampled at the tropical high-altitude site of Chacaltaya using WRF-FLEXPART and cluster analysis2021Ingår i: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 21, nr 21, s. 16453-16477Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Observations of aerosol and trace gases in the remote troposphere are vital to quantify background concentrations and identify long-term trends in atmospheric composition on large spatial scales. Measurements made at high altitude are often used to study free-tropospheric air; however such high-altitude sites can be influenced by boundary layer air masses. Thus, accurate information on air mass origin and transport pathways to high-altitude sites is required. Here we present a new method, based on the source-receptor relationship (SRR) obtained from backwards WRF-FLEXPART simulations and a k-means clustering approach, to identify source regions of air masses arriving at measurement sites. Our method is tailored to areas of complex terrain and to stations influenced by both local and long-range sources. We have applied this method to the Chacaltaya (CHC) GAW station (5240 m a.s.l.; 16.35 degrees S, 68.13 degrees W) for the 6-month duration of the Southern Hemisphere high-altitude experiment on particle nucleation and growth (SALILNA) to identify where sampled air masses originate and to quantify the influence of the surface and the free troposphere. A key aspect of our method is that it is probabilistic, and for each observation time, more than one air mass (cluster) can influence the station, and the percentage influence of each air mass can be quantified. This is in contrast to binary methods, which label each observation time as influenced by either boundary layer or free-troposphere air masses. Air sampled at CHC is a mix of different provenance. We find that on average 9 % of the air, at any given observation time, has been in contact with the surface within 4 d prior to arriving at CHC. Furthermore, 24 % of the air has been located within the first 1.5 km above ground level (surface included). Consequently, 76 % of the air sampled at CHC originates from the free troposphere. However, pure free-tropospheric influences are rare, and often samples are concurrently influenced by both boundary layer and free-tropospheric air masses. A clear diurnal cycle is present, with very few air masses that have been in contact with the surface being detected at night. The 6-month analysis also shows that the most dominant air mass (cluster) originates in the Amazon and is responsible for 29 % of the sampled air. Furthermore, short-range clusters (origins within 100 km of CHC) have high temporal frequency modulated by local meteorology driven by the diurnal cycle, whereas the mid- and long-range clusters' (> 200 km) variability occurs on timescales governed by synoptic-scale dynamics. To verify the reliability of our method, in situ sulfate observations from CHC are combined with the SRR clusters to correctly identify the (pre-known) source of the sulfate: the Sabancaya volcano located 400 km north-west from the station.

  • 11.
    Almamoun, Radwa
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Toxicological studies of di-n-butyl phthalate (DBP): Impact on the reproductive system and gut microbiota2024Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The potential health impact of exposure to anthropogenic chemicals has raised major concerns worldwide. Phthalates are mainly used in the plastic industry and have been associated with adverse effects in humans. Di-n-butyl phthalate (DBP) is one of the dominant phthalates with a ubiquitous presence in the environment. While many studies have examined the endocrine disrupting properties of DBP, with a focus on developmental and reproductive dysfunctions, studies of its effects on the adult reproductive system and gut microbiota are limited. This thesis aimed to determine persistent effects of DBP on the adult male reproductive system, provide a high-throughput screening tool for identifying reproductive toxicants, and characterize the effects of DBP on the gut microbiota.

       Paper I investigated if adult DBP exposure can induce persistent effects on the mature reproductive system. Adult male mice were orally exposed to 10 or 100 mg/kg/day for five weeks and testes were collected one week after the last dose. The results demonstrated a significant decrease in testosterone levels in the DBP-exposed groups. Mechanistically, the levels of steroidogenic enzymes, cell-specific markers and oxidative stress were increased. In paper II, elements of the in vivo testicular microenvironment, including functional testosterone production, were modeled using a three-dimensional (3D) heterogenous testicular cell co-culture derived from neonatal mice. Automated high-content imaging of cell-specific markers confirmed the presence of germ cells (DAZL+), Leydig cells (CYP11A1+), and Sertoli cells (SOX9+). DBP exposure decreased testosterone production, as well as levels of the steroidogenic enzyme CYP11A1, and the steroidogenic regulator StAR. Overall, this in vitro 3D model recapitulates the testicular pathways involved in DBP toxicity, making it a relevant tool for assessing reprotoxic effects of chemicals.

       Paper III investigated the impact of oral DBP exposure on the gut microbiota and the potential interplay with immune and testicular toxicity using 16S rRNA sequencing. DBP-treated mice showed a distinct microbial composition and numerous differentially abundant amplicon sequence variants. Interestingly, the microbial alterations correlated with an increase in non-classical monocytes observed in DBP-exposed mice. In paper IV, a shotgun metagenomic analysis was conducted to achieve a more comprehensive characterization of the DBP-induced effects on gut microbiota composition and function. The DBP-exposed mice had a higher abundance of Adlercreutzia mucosicola, a bacterium linked with intestinal inflammation. In contrast, the beneficial Akkermansia muciniphila was less abundant in DBP-exposed mice. Functional analysis demonstrated that DBP exposure increased the abundance of genes involved in environmental sensing and antimicrobial resistance.

       In conclusion, this doctoral thesis demonstrates the antiandrogenic effects of DBP as well as potential underlying mechanisms of testicular dysfunction in adult mice. In addition, we established a powerful in vitro tool for screening reprotoxic effects. The gut microbiota was also impaired by DBP exposure, which may play a potential role in initiating or exacerbating the DBP-induced toxicity. Overall, this work highlights the potential health impact of the interplay between the two exposome components, chemical exposure and gut microbiota.

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    Toxicological studies of di-n-butyl phthalate (DBP)
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  • 12.
    Almamoun, Radwa
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap. Stockholms universitet, Science for Life Laboratory (SciLifeLab).
    Pierozan, Paula
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap. Stockholms universitet, Science for Life Laboratory (SciLifeLab).
    Karlsson, Oskar
    Stockholms universitet, Science for Life Laboratory (SciLifeLab). Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Mechanistic screening of reproductive toxicity in a 3D testicular co-culture shows significant impairments following exposure to low dibutyl phthalate concentrationsManuskript (preprint) (Övrigt vetenskapligt)
  • 13.
    Almamoun, Radwa
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap. Stockholms universitet, Science for Life Laboratory (SciLifeLab).
    Pierozan, Paula
    Stockholms universitet, Science for Life Laboratory (SciLifeLab). Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Karlsson, Oskar
    Stockholms universitet, Science for Life Laboratory (SciLifeLab). Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Mechanistic screening of reproductive toxicity in a novel 3D testicular co-culture model shows significant impairments following exposure to low-dibutyl phthalate concentrations2024Ingår i: Archives of Toxicology, ISSN 0340-5761, E-ISSN 1432-0738Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To improve the mechanistic screening of reproductive toxicants in  chemical-risk assessment and drug development, we have developed a three-dimensional (3D) heterogenous testicular co-culture model from neonatal mice. Di-n-butyl phthalate (DBP), an environmental contaminant that can affect reproductive health negatively, was used as a model compound to illustrate the utility of the in vitro model. The cells were treated with DBP (1 nM to 100 µM) for 7 days. Automated high-content imaging confirmed the presence of cell-specific markers of Leydig cells (CYP11A1 +), Sertoli cells (SOX9 +), and germ cells (DAZL +). Steroidogenic activity of Leydig cells was demonstrated by analyzing testosterone levels in the culture medium. DBP induced a concentration-dependent reduction in testosterone levels and decreased the number of Leydig cells compared to vehicle control. The levels of steroidogenic regulator StAR and the steroidogenic enzyme CYP11A1 were decreased already at the lowest DBP concentration (1 nM), demonstrating upstream effects in the testosterone biosynthesis pathway. Furthermore, exposure to 10 nM DBP decreased the levels of the germ cell-specific RNA binding protein DAZL, central for the spermatogenesis. The 3D model also captured the development of the Sertoli cell junction proteins, N-cadherin and Zonula occludens protein 1 (ZO-1), critical for the blood–testis barrier. However, DBP exposure did not significantly alter the cadherin and ZO-1 levels. Altogether, this 3D in vitro system models testicular cellular signaling and function, making it a powerful tool for mechanistic screening of developmental testicular toxicity. This can open a new avenue for high throughput screening of chemically-induced reproductive toxicity during sensitive developmental phases.

  • 14.
    Almamoun, Radwa
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap. Stockholms universitet, Science for Life Laboratory (SciLifeLab).
    Pierozan, Paula
    Stockholms universitet, Science for Life Laboratory (SciLifeLab). Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Manoharan, Lokeshwaran
    Karlsson, Oskar
    Stockholms universitet, Science for Life Laboratory (SciLifeLab). Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Altered gut microbiota community structure and correlated immune system changes in dibutyl phthalate exposed mice2023Ingår i: Ecotoxicology and Environmental Safety, ISSN 0147-6513, E-ISSN 1090-2414, Vol. 262, artikel-id 115321Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Di-n-butyl phthalate (DBP) is a ubiquitous environmental contaminant linked with various adverse health effects, including immune system dysfunction. Gut microbial dysbiosis can contribute to a wide range of pathogenesis, particularly immune disease. Here, we investigated the impact of DBP on the gut microbiome and examined correlations with immune system changes after five weeks oral exposure (10 or 100 mg/kg/day) in adult male mice. The fecal microbiome composition was characterized using 16S rRNA sequencing. DBP-treated mice displayed a significantly distinct microbial community composition, indicated by Bray-Curtis distance. Numerous amplicon sequence variants (ASVs) at the genus level were altered. Compared to the vehicle control group, the 10 mg/kg/day DBP group had 63 more abundant and 65 less abundant ASVs, while 60 ASVs were increased and 76 ASVs were decreased in the 100 mg/kg/day DBP group. Both DBP treatment groups showed higher abundances of ASVs assigned to Desulfovibrio (Proteobacteria phylum) and Enterorhabdus genera, while ASVs belonging to Parabacteroides, Lachnospiraceae UCG-006 and Lachnoclostridium were less common compared to the control group. Interestingly, an ASV belonging to Rumniniclostridium 6, which was less abundant in DBP-treated mice, demonstrated a negative correlation with the increased number of non-classical monocytes observed in the blood of DBP-treated animals. In addition, an ASV from Lachnospiraceae UCG-001, which was more abundant in the DBP-treated animals, showed a positive correlation with the non-classical monocyte increase. This study shows that DBP exposure greatly modifies the gut bacterial microbiome and indicates a potential contribution of microbial dysbiosis to DBP-induced immune system impairment, illustrating the importance of investigating how interactions between exposome components can affect health.

  • 15.
    Almamoun, Radwa
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap. Stockholms universitet, Science for Life Laboratory (SciLifeLab).
    Pierozan, Paula
    Stockholms universitet, Science for Life Laboratory (SciLifeLab). Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Sundh, John
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik. Stockholms universitet, Science for Life Laboratory (SciLifeLab).
    Karlsson, Oskar
    Stockholms universitet, Science for Life Laboratory (SciLifeLab). Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Shotgun metagenomic analysis of gut microbiota in dibutyl phthalate exposed miceManuskript (preprint) (Övrigt vetenskapligt)
  • 16.
    Alqudah, Laith
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Olika luftföroreningars påverkan på variationen i exponeringen och hälsoriskerna vid cykling i StockholmLaith Al-QudahInstitutionen för2022Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Luftföroreningarna är det miljöproblem som orsakar mest negativa effekter på människors hälsa. Trafiken är en av de största källorna till luftföroreningar i stadsmiljöer. Flera tidigare genomförda studier har bedömt luftföroreningarnas inverkan på människors hälsa genom att uppskatta exponeringen med hjälp av olika beräkningsmodeller som använder data från fasta mätstationer. Syfte med det här projektet var att undersöka variationerna i luftföroreningsexponeringen för olika luftföroreningar och de hälsoriskerna som är förknippade med dessa luftföroreningar. Det genomfördes genom att i andningshöjd mäta NOx, NO, NO2, PM2.5, PM2.5 – 10, PM10 och BC samt total antalet partiklar (nano-PM) i realtid från olika cykelvägar i Stockholm. Till mätningarna användes fem olika mätinstrument. Total genomfördes 20 mätningstillfällen längs med olika gator i Stockholm med en total mättid om ca 40 timmar och med distansen 429 km. Mätningarna genomfördes mellan 7 och 24 februari 2022 på vardagar under rusningstrafik kl. 07-09 och kl. 16-18. GIS-baserade kartor har använts till hjälp för att analysera och redovisa mätningarna. Data för hjärtfrekvenser och tidloggar mättes med hjälp av en smartklocka och nyttjades för spårning av mätningarna och i beräkningen av total inhalerade luftföroreningar. Resultaten visar att luftföroreningarna kan variera från ett område till ett annat även enligt mättiden. Varken BC-, LDSA-, partikelstorleks-, eller PM2.5-mätningarna hade en signifikant skillnad i de tre delområdena eller mätpassen. Halterna av PM2.5–10 och PM10 var signifikant högre på kvällen än på morgonen. Antal nanopartiklarna var signifikant högre på kvällen inom delområde A, men var högre på morgonen i delområde B och C. Ungefär 39 μg BC, 1379 μg PM2.5 och 9*1011 nanopartiklar har total inhalerats under samtliga genomförda mättillfällen, och utav dessa mängder har ungefär 1*109 μm2 av nanopartiklarnas ytarea deponerats i lungorna. Mätningarna visar på en signifikant korrelation mellan Lung Deposited Surface Area (LDSA) och BC (r2=0,79). Om man antar att LDSA är en indikator av nano partiklarnas toxiska effekter, då BC’s korrelation med LDSA är konsistent med att epidemiologiska studier visat att BC kan öka risken för förtida död och sjukdomar. Detta indikerar att exponeringen för sot- och nanopartiklar som släpps ut vid ofullständig bränsleförbränning är viktiga för påverkan på cyklisters hälsa.

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  • 17. Amorim, Jorge H.
    et al.
    Engardt, Magnuz
    Johansson, Christer
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap. Environment and Health Administration, Sweden.
    Ribeiro, Isabel
    Sannebro, Magnus
    Regulating and Cultural Ecosystem Services of Urban Green Infrastructure in the Nordic Countries: A Systematic Review2021Ingår i: International Journal of Environmental Research and Public Health, ISSN 1661-7827, E-ISSN 1660-4601, Vol. 18, nr 3, artikel-id 1219Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    In the Nordic countries (Denmark, Finland, Iceland, Norway and Sweden), the Urban Green Infrastructure (UGI) has been traditionally targeted at reducing flood risk. However, other Ecosystem Services (ES) became increasingly relevant in response to the challenges of urbanization and climate change. In total, 90 scientific articles addressing ES considered crucial contributions to the quality of life in cities are reviewed. These are classified as (1) regulating ES that minimize hazards such as heat, floods, air pollution and noise, and (2) cultural ES that promote well-being and health. We conclude that the planning and design of UGI should balance both the provision of ES and their side effects and disservices, aspects that seem to have been only marginally investigated. Climate-sensitive planning practices are critical to guarantee that seasonal climate variability is accounted for at high-latitude regions. Nevertheless, diverging and seemingly inconsistent findings, together with gaps in the understanding of long-term effects, create obstacles for practitioners. Additionally, the limited involvement of end users points to a need of better engagement and communication, which in overall call for more collaborative research. Close relationships and interactions among different ES provided by urban greenery were found, yet few studies attempted an integrated evaluation. We argue that promoting interdisciplinary studies is fundamental to attain a holistic understanding of how plant traits affect the resulting ES; of the synergies between biophysical, physiological and psychological processes; and of the potential disservices of UGI, specifically in Nordic cities.

  • 18. Anderson, J. K.
    et al.
    Brecher, R. W.
    Cousins, Ian T.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    DeWitt, J.
    Fiedler, H.
    Kannan, K.
    Kirman, C. R.
    Lipscomb, J.
    Priestly, B.
    Schoeny, R.
    Seed, J.
    Verner, M.
    Hays, S. M.
    Grouping of PFAS for human health risk assessment: Findings from an independent panel of experts2022Ingår i: Regulatory toxicology and pharmacology, ISSN 0273-2300, E-ISSN 1096-0295, Vol. 134, artikel-id 105226Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An expert panel was convened to provide insight and guidance on per-and polyfluoroalkyl substances (PFAS) grouping for the purposes of protecting human health from drinking water exposures, and how risks to PFAS mixtures should be assessed. These questions were addressed through multiple rounds of blind, independent responses to charge questions, and review and comments on co-panelists responses. The experts agreed that the lack of consistent interpretations of human health risk for well-studied PFAS and the lack of information for the vast majority of PFAS present significant challenges for any mixtures risk assessment approach. Most experts agreed that all PFAS should not be grouped together, persistence alone is not sufficient for grouping PFAS for the purposes of assessing human health risk, and that the definition of appropriate subgroups can only be defined on a case-by-case manner. Most panelists agreed that it is inappropriate to assume equal toxicity/potency across the diverse class of PFAS. A tiered approach combining multiple lines of evidence was presented as a possible viable means for addressing PFAS that lack analytical and/or toxicological studies. Most PFAS risk assessments will need to employ assumptions that are more likely to overestimate risk than to underestimate risk, given the choice of assumptions regarding dose-response model, uncertainty factors, and exposure information.

  • 19. Andersson, Agneta
    et al.
    Grinienė, Evelina
    Berglund, Åsa M. M.
    Brugel, Sonia
    Gorokhova, Elena
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Figueroa, Daniela
    Gallampois, Christine
    Ripszam, Matyas
    Tysklind, Mats
    Microbial food web changes induced by terrestrial organic matter and elevated temperature in the coastal northern Baltic Sea2023Ingår i: Frontiers in Marine Science, E-ISSN 2296-7745, Vol. 10, artikel-id 1170054Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Climate change has been projected to cause increased temperature and amplified inflows of terrestrial organic matter to coastal areas in northern Europe. Consequently, changes at the base of the food web favoring heterotrophic bacteria over phytoplankton are expected, affecting the food web structure. We tested this hypothesis using an outdoor shallow mesocosm system in the northern Baltic Sea in early summer, where the effects of increased temperature (+ 3°C) and terrestrial matter inputs were studied following the system dynamics and conducting grazing experiments. Juvenile perch constituted the highest trophic level in the system, which exerted strong predation on the zooplankton community. Perch subsequently released the microbial food web from heavy grazing by mesozooplankton. Addition of terrestrial matter had a stronger effect on the microbial food web than the temperature increase, because terrestrial organic matter and accompanying nutrients promoted both heterotrophic bacterial production and phytoplankton primary production. Moreover, due to the shallow water column in the experiment, terrestrial matter addition did not reduce the light below the photosynthesis saturation level, and in these conditions, the net-autotrophy was strengthened by terrestrial matter enrichment. In combination with elevated temperature, the terrestrial matter addition effects were intensified, further shifting the size distribution of the microbial food web base from picoplankton to microphytoplankton. These changes up the food web led to increase in the biomass and proportion of large-sized ciliates (>60 µm) and rotifers. Despite the shifts in the microbial food web size structure, grazing experiments suggested that the pathway from picoplankton to nano- and microzooplankton constituted the major energy flow in all treatments. The study implies that the microbial food web compartments in shallow coastal waters will adjust to climate induced increased inputs of terrestrial matter and elevated temperature, and that the major energy path will flow from picoplankton to large-sized ciliates during the summer period.

     

  • 20.
    Andersson, August
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Mechanisms for log normal concentration distributions in the environment2021Ingår i: Scientific Reports, E-ISSN 2045-2322, Vol. 11, nr 1, artikel-id 16418Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Log normal-like concentration distributions are ubiquitously observed in the environment. However, the mechanistic origins are not well understood. In this paper, we show that first order exponential kinetics onsets log-normal concentration distributions, under certain assumptions. Given the ubiquity of exponential kinetics, e.g., source and sink processes, this model suggests an explanation for the frequent observation in the environment, and elsewhere. We compare this model to other mechanisms affecting concentration distributions, e.g., source mixing. Finally, we discuss possible implications for data analysis and modelling, e.g., log-normal rates and fluxes.

  • 21.
    Andersson, August
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Kirillova, Elena N.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap. National Research Council of Italy, Italy.
    Decesari, Stefano
    DeWitt, H. Langley
    Gasore, Jimmy
    Potter, Katherine
    Prinn, Ronald G.
    Rupakheti, Maheswar
    Ndikubwimana, Jean de Dieu
    Nkusi, Julius
    Safari, Bonfils
    Seasonal source variability of carbonaceous aerosols at the Rwanda Climate Observatory2020Ingår i: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 20, nr 8, s. 4561-4573Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Sub-Saharan Africa (SSA) is a global hot spot for aerosol emissions, which affect the regional climate and air quality. In this paper, we use ground-based observations to address the large uncertainties in the source-resolved emission estimation of carbonaceous aerosols. Ambient fine fraction aerosol was collected on filters at the high-altitude (2590 m a.s.1.) Rwanda Climate Observatory (RCO), a SSA background site, during the dry and wet seasons in 2014 and 2015. The concentrations of both the carbonaceous and inorganic ion components show a strong seasonal cycle, with highly elevated concentrations during the dry season. Source marker ratios, including carbon isotopes, show that the wet and dry seasons have distinct aerosol compositions. The dry season is characterized by elevated amounts of biomass burning products, which approach similar to 95 % for carbonaceous aerosols. An isotopic mass-balance estimate shows that the amount of the carbonaceous aerosol stemming from savanna fires may increase from 0.2 mu g m(-3) in the wet season up to 10 mu g m(-3) during the dry season. Based on these results, we quantitatively show that savanna fire is the key modulator of the seasonal aerosol composition variability at the RCO.

  • 22.
    Andersson, Erik
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholm Resilience Centre. North-West University, South Africa.
    Boonstra, Wiebren J.
    de la Torre Castro, Maricela
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Hughes, Alice C.
    Ilstedt, Ulrik
    Jernelöv, Arne
    Jonsson, Bengt-Gunnar
    Kalantari, Zahra
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi. KTH Royal Institute of Technology, Sweden.
    Keskitalo, Carina
    Kritzberg, Emma
    Kätterer, Thomas
    McNeely, Jeffrey A.
    Mohr, Claudia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Mustonen, Tero
    Ostwald, Madelene
    Reyes-Garcia, Victoria
    Rusch, Graciela M.
    Sanderson Bellamy, Angelina
    Stage, Jesper
    Tedengren, Michael
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Thomas, David N.
    Wulff, Angela
    Söderström, Bo
    Ambio fit for the 2020s2022Ingår i: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 51, nr 5, s. 1091-1093Artikel i tidskrift (Övrigt vetenskapligt)
  • 23.
    Andersson, Mathias
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Spridning av legionärssjuka från kyltorn: En litteraturstudie över riskfaktorer i historiska utbrott mellan år 2000 – 2017, och en riskanalys av kyltorn i Upplands Väsby kommun2022Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Legionella Legionella spp är en bakterie som kan orsaka svåra sjukdomar hos människor. När bakterien genom råvatten sprids till artificiella vattensystem finns det en risk att de växer till höga koncentrationer och sprids till människor. Kyltorn, vilket bland annat används inom industri och luftkonditionering, är ett vattensystem som kan sprida legionella med aerosoler. Med gedigen skötsel kan dock riskerna för legionellatillväxt minska.

    Idag krävs det ingen anmälan eller tillstånd för att driva ett kyltorn, vilket leder till att tillsynsmyndigheterna i Sverige har låg kunskap om vilka kyltorn som finns. Som konsekvens kan det ta lång tid att stänga av kyltorn vid händelse att ett kyltorn börjar sprida legionella, och det finns inte heller någon säkerhet i att kyltornen sköts med rätt metoder för att reducera risken för legionella.

    Detta examensarbete syftade till att undersöka vilka riskfaktorer som har förekommit mest frekvent iinternationella och nationella legionellautbrott samt att undersöka hur många kyltorn som finns i Upplands Väsby och undersöka hur dessa kyltorn underhålls. Brister i skötseln kopplades till identifierade riskfaktorer i litteraturstudien för att bedöma spridningsrisk av legionella från kyltorn i Upplands Väsby.

    Den metod som använts är litteraturgranskning av historiska legionellautbrott med kyltorn som spridningskälla, en inledande inventering av verksamheter i Upplands Väsby samt en enkätstudie.

    Studien visade att det finns en kärna av fem riskfaktorer som är vanligt förekommande i legionellautbrott. Dessa är bristande rutiner vid applicering av biocider, höga utomhustemperaturer, förekomst av biofilm, bristande rutiner vid driftstopp samt bristande underhållsdokumentation. Resultaten från enkätstudien påvisade generella brister vid applicering av biocider och kontroll av biofilm. Rutinerna kring driftstopp, kalkavlagring och mekanisk rengöring var starka områden i verksamheternas skötsel. Det finns dock en stor variation i hur bra verksamheterna i kommunen sköter sina kyltorn. Det bedöms finnas en risk för spridning av legionella i Upplands Väsby, då minst en av de fyra studerade verksamheterna uppvisar bristande skötsel för biocider, biofilm och vid driftstopp – vilket är tre av de fem vanligaste identifierade riskfaktorerna i historiska utbrott.

  • 24.
    Andrén, Cecilia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    IKEU 2008 surstötar i vattendrag: Årsrapport episoder2009Rapport (Övrigt vetenskapligt)
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  • 25.
    Andrén, Cecilia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Studier av episodisk försurning i IKEU-projektet2005Rapport (Övrigt vetenskapligt)
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  • 26.
    Andrén, Cecilia M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    IKEU - Specialprojekt S9: Episoder i vattendrag2006Rapport (Övrigt vetenskapligt)
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  • 27.
    Andrén, Cecilia M.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Jarlman, Amelie
    Bentiska kiselalger som surhetsindikatorer i rinnande vatten2006Rapport (Övrigt vetenskapligt)
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  • 28. Antacli, J. C.
    et al.
    Di Mauro, R.
    Rimondino, G. N.
    Alurralde, Gastón
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap. Baltic Marine Environment Protection Commission HELCOM, Finland.
    Schloss, I. R.
    González, A.
    Morales, S.
    Ottero, A.
    Vodopivez, C.
    Microplastic pollution in waters of the Antarctic coastal environment of Potter Cove (25 de Mayo Island/King George Island, South Shetlands)2024Ingår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 915, artikel-id 170155Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Plastic pollution in the Southern Ocean around Antarctica is a growing concern, but many areas in this vast region remain unexplored. This study provides the first comprehensive analysis of marine microplastic (MPs) concentrations in Potter Cove, located near the Argentinian Carlini research station on 25 de Mayo/King George Island, Antarctica. Water samples were collected at 14 sites within the cove, representing various influences from the station's activities. Two sampling methods were used: a 5 L Niskin bottle and an in-situ filtering device called Microfilter, allowing for large water volumes to be filtered. MPs were found in 100 % of the samples. Microfilter samples ranged from 0.02 to 2.14 MPs/L, with a mean concentration of 0.44 ± 0.44 MPs/L. Niskin bottle samples showed concentrations from 0.40 to 55.67 MPs/L, with a mean concentration of 19.03 ± 18.21 MPs/L. The dominant types of MPs were anthropogenic black, transparent, and pink microfibers (MFs) measuring between 0.11 and 3.6 mm (Microfilter) and 0.06 to 7.96 mm (Niskin bottle), with a median length of 0.01 mm for both methods. Transparent and black irregular microfragments (MFRs) with diameters from 0.10 to 5.08 mm and a median diameter of 0.49 mm were also prevalent. FTIR-spectroscopy revealed the presence of 14 types of polymers. Cellulose-based materials and polyethylene terephthalate were the most abundant in MFs, while polyurethanes and styrene-based copolymers dominated in MFRs. MPs were more abundant near the Carlini station. Compared to other coastal Antarctic areas, the MPs in the cove were relatively abundant and mostly smaller than 1 mm. Local activities on the island were identified as the primary source of MPs in the cove, and the cyclonic water circulation likely affects the distribution of small-sized particles. To protect the ecosystem, reducing plastic usage, improving waste management, regulating MPs debris, and enhancing wastewater practices are essential.

  • 29. Arp, Hans Peter H.
    et al.
    Kühnel, Dana
    Rummel, Christoph
    MacLeod, Matthew
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Potthoff, Annegret
    Reichelt, Sophia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Rojo-Nieto, Elisa
    Schmitt-Jansen, Mechthild
    Sonnenberg, Johanna
    Toorman, Erik
    Jahnke, Annika
    Weathering Plastics as a Planetary Boundary Threat: Exposure, Fate, and Hazards2021Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 55, nr 11, s. 7246-7255Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We described in 2017 how weathering plastic litter in the marine environment fulfils two of three criteria to impose a planetary boundary threat related to chemical pollution and the release of novel entities: (1) planetary-scale exposure, which (2) is not readily reversible. Whether marine plastics meet the third criterion, (3) eliciting a disruptive impact on vital earth system processes, was uncertain. Since then, several important discoveries have been made to motivate a re-evaluation. A key issue is if weathering macroplastics, microplastics, nanoplastics, and their leachates have an inherently higher potential to elicit adverse effects than natural particles of the same size. We summarize novel findings related to weathering plastic in the context of the planetary boundary threat criteria that demonstrate (1) increasing exposure, (2) fate processes leading to poorly reversible pollution, and (3) (eco)toxicological hazards and their thresholds. We provide evidence that the third criterion could be fulfilled for weathering plastics in sensitive environments and therefore conclude that weathering plastics pose a planetary boundary threat. We suggest future research priorities to better understand (eco)toxicological hazards modulated by increasing exposure and continuous weathering processes, to better parametrize the planetary boundary threshold for plastic pollution.

  • 30. Artaxo, Paulo
    et al.
    Hansson, Hans-Christen
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Andreae, Meinrat O.
    Bäck, Jaana
    Alves, Eliane Gomes
    Barbosa, Henrique M. J.
    Bender, Frida
    Stockholms universitet, Naturvetenskapliga fakulteten, Meteorologiska institutionen (MISU).
    Bourtsoukidis, Efstratios
    Carbone, Samara
    Chi, Jinshu
    Decesari, Stefano
    Després, Viviane R.
    Ditas, Florian
    Ezhova, Ekaterina
    Fuzzi, Sandro
    Hasselquist, Niles J.
    Heintzenberg, Jost
    Holanda, Bruna A.
    Guenther, Alex
    Hakola, Hannele
    Heikkinen, Liine
    Kerminen, Veli-Matti
    Kontkanen, Jenni
    Krejci, Radovan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Kulmala, Markku
    Lavric, Jost V.
    de Leeuw, Gerrit
    Lehtipalo, Katrianne
    Machado, Luiz Augusto T.
    McFiggans, Gordon
    Franco, Marco Aurelio M.
    Meller, Bruno Backes
    Morais, Fernando G.
    Mohr, Claudia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Morgan, William
    Nilsson, Mats B.
    Peichl, Matthias
    Petäjä, Tuukka
    Praß, Maria
    Pöhlker, Christopher
    Pöhlker, Mira L.
    Pöschl, Ulrich
    Von Randow, Celso
    Riipinen, Ilona
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Rinne, Janne
    Rizzo, Luciana
    Rosenfeld, Daniel
    Silva Dias, Maria A. F.
    Sogacheva, Larisa
    Stier, Philip
    Swietlicki, Erik
    Sörgel, Matthias
    Tunved, Peter
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Virkkula, Aki
    Wang, Jian
    Weber, Bettina
    Maria Yáñez-Serrano, Ana
    Zieger, Paul
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Mikhailov, Eugene
    Smith, James N.
    Kesselmeier, Jürgen
    Tropical and Boreal Forest – Atmosphere Interactions: A Review2022Ingår i: Tellus. Series B, Chemical and physical meteorology, ISSN 0280-6509, E-ISSN 1600-0889, Vol. 74, nr 1, s. 24-163Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    This review presents how the boreal and the tropical forests affect the atmosphere, its chemical composition, its function, and further how that affects the climate and, in return, the ecosystems through feedback processes. Observations from key tower sites standing out due to their long-term comprehensive observations: The Amazon Tall Tower Observatory in Central Amazonia, the Zotino Tall Tower Observatory in Siberia, and the Station to Measure Ecosystem-Atmosphere Relations at Hyytiäla in Finland. The review is complemented by short-term observations from networks and large experiments.

    The review discusses atmospheric chemistry observations, aerosol formation and processing, physiochemical aerosol, and cloud condensation nuclei properties and finds surprising similarities and important differences in the two ecosystems. The aerosol concentrations and chemistry are similar, particularly concerning the main chemical components, both dominated by an organic fraction, while the boreal ecosystem has generally higher concentrations of inorganics, due to higher influence of long-range transported air pollution. The emissions of biogenic volatile organic compounds are dominated by isoprene and monoterpene in the tropical and boreal regions, respectively, being the main precursors of the organic aerosol fraction.

    Observations and modeling studies show that climate change and deforestation affect the ecosystems such that the carbon and hydrological cycles in Amazonia are changing to carbon neutrality and affect precipitation downwind. In Africa, the tropical forests are so far maintaining their carbon sink.

    It is urgent to better understand the interaction between these major ecosystems, the atmosphere, and climate, which calls for more observation sites, providing long-term data on water, carbon, and other biogeochemical cycles. This is essential in finding a sustainable balance between forest preservation and reforestation versus a potential increase in food production and biofuels, which are critical in maintaining ecosystem services and global climate stability. Reducing global warming and deforestation is vital for tropical forests.

  • 31. Astray, Blanca
    et al.
    Sipkova, Adela
    Baragano, Diego
    Pechar, Jan
    Krejci, Radovan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap. Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap och analytisk kemi. Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för tillämpad miljövetenskap (ITM). Stockholms universitet, Naturvetenskapliga fakulteten, Meteorologiska institutionen (MISU). Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI). Stockholm Univ, Dept Environm Sci, Atmospher Sci Unit, S-10691 Stockholm, Sweden.
    Komarek, Michael
    Chrastny, Vladislav
    Measuring Pb isotope ratios in fresh snow filtrate refines the apportioning of contaminant sources in the Arctic2024Ingår i: Environmental Pollution, ISSN 0269-7491, E-ISSN 1873-6424, Vol. 345, s. 123457-, artikel-id 123457Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The remoteness and low population in the Arctic allow us to study global environmental processes, where the analysis of indicators can provide useful information about local and distant pollution sources. Fresh snow represents a convenient indicator of regional and transboundary atmospheric contamination sources, entrapping aerosols, and particulates like a natural autosampler of the environment. Lead stable isotopes are widely used to trace and monitor local and distant pollution sources. However, the behavior of Pb within different snow components is still not thoroughly studied, and its significance could be underestimated if only larger particulates are accounted for. We collected snow and samples from potential sources (fuel, rocks, coal) in three Arctic localities: Nuuk (Greenland), Reykjavik (Iceland), and Longyearbyen (Svalbard). We separated the filtrate from the filter residue through 0.45 mu m nitrocellulose membranes to isolate the low-diameter particles associated with long-range transport from larger particles of mostly local natural origin. Filtrates yielded higher EFs (enrichment factor as the Pb/Al ratio relative to the upper crust) than filtration residues (80 +/- 104 and 2.1 +/- 1.1, respectively), and Pb isotope signals similar to fuel and coal (206Pb/207Pb are 1.199 +/- 0.028 in coal, 1.168 +/- 0.029 in filtrates, 1.163 +/- 0.013 in fuel, 1.137 +/- 0.045 in residues, and 0.985 +/- 0.020 in rocks). In contrast to filtrates, the filter residues present wider ranges of Pb isotope compositions and crustal contributions and lower EFs, so we suggest that filtrate contains Pb from fuel combustion more selectively, while the residue carries a more considerable contribution of local mineral dust that can mask the contribution of other anthropogenic or distant natural sources. These findings add weight to the notion that filtrates are a more selective measure of metal deposition from long-range anthropogenic emissions compared to analyzing bulk melted snow or only filter residues.

  • 32.
    Awad, Raed
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap. Swedish Environmental Research Institute (IVL), Sweden.
    Zhou, Yihui
    Nyberg, Elisabeth
    Namazkar, Shahla
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Yongning, Wu
    Xiao, Qianfen
    Sun, Yaije
    Zhu, Zhiliang
    Bergman, Åke
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap. Tongji University, China; Örebro University, Sweden.
    Benskin, Jonathan P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Emerging per- and polyfluoroalkyl substances (PFAS) in human milk from Sweden and China2020Ingår i: Environmental Science: Processes & Impacts, ISSN 2050-7887, E-ISSN 2050-7895, Vol. 22, nr 10, s. 2023-2030Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Twenty per- and polyfluoroalkyl substances (PFAS) were determined in human milk from residents of three Chinese cities (Shanghai, Jiaxing, and Shaoxing; [n= 10 individuals per city]), sampled between 2010 and 2016. These data were compared to a combination of new and previously reported PFAS concentrations in human milk from Stockholm, Sweden, collected in 2016 (n= 10 individuals). Across the three Chinese cities, perfluorooctanoate (PFOA; sum isomers), 9-chlorohexadecafluoro-3-oxanone-1-sulfonic acid (9Cl-PF3ONS; also known as 6:2 Cl-PFESA or by its trade name F53-B), and perfluorooctane sulfonate (PFOS; sum isomers) occurred at the highest concentrations among all PFAS (up to 411, 976, and 321 pg mL(-1), respectively), while in Stockholm, PFOA and PFOS were dominant (up to 89 and 72 pg mL(-1), respectively). 3H-Perfluoro-3-[(3-methoxy-propoxy)propanoic acid] (ADONA) was intermittently detected but at concentrations below the method quantification limit (i.e.<10 pg mL(-1)) in Chinese samples, and was non-detectable in Swedish milk. The extremely high concentrations of F53-B in Chinese milk suggest that human exposure assessments focused only on legacy substances may severely underestimate overall PFAS exposure in breastfeeding infants.

  • 33. Awchi, Mo
    et al.
    Gebbink, Wouter A.
    Berendsen, Bjorn J. A.
    Benskin, Jonathan P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    van Leeuwen, Stefan P. J.
    Development, validation, and application of a new method for the quantitative determination of monohydrogen-substituted perfluoroalkyl carboxylic acids (H-PFCAs) in surface water2022Ingår i: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 287, artikel-id 132143Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Per- and polyfluoroalkyl substances (PFASs) are a large and diverse class of chemicals. While some have been phased out internationally due to concerns over their human and environmental health risks, novel alternative PFASs continue to be manufactured and detected in environmental samples. The occurrence and fate of these alternatives remain poorly understood. The present study investigated the occurrence of an emerging class of PFAS alternative, the monohydrogen-substituted perfluoroalkyl carboxylic acids (H-PFCAs), in conjunction with the more well-known PFCAs. A weak anion exchange solid phase extraction-liquid chromatography tandem mass spectrometry method for quantitative determination of H-PFCAs in surface water was developed, validated, and applied on samples collected from the Netherlands. To improve chromatography, especially for short-chain (H-) PFCAs, an ion-pairing agent, tetrabutylammonium hydrogen sulphate, was used. The method was validated for linearity (R2 > 0.99), instrumental detection limits (0.01-0.09 ng/mL), method detection limits (0.03-0.75 ng/ mL), matrix effects (<20%), percent absolute- and relative recovery (57-121%), trueness (130-80%), repeatability (<20%), and within-lab reproducibility (<20%). Eleven out of fourteen PFASs showed acceptable results. Application of the newly validated method to surface water throughout the Netherlands revealed trace levels of H-PFCAs (including two new H-PFCAs) and high concentrations of PFCAs.

  • 34. Baccarini, Andrea
    et al.
    Karlsson, Linn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Dommen, Josef
    Duplessis, Patrick
    Vüllers, Jutta
    Brooks, Ian M.
    Saiz-Lopez, Alfonso
    Salter, Matthew
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Tjernström, Michael
    Stockholms universitet, Naturvetenskapliga fakulteten, Meteorologiska institutionen (MISU).
    Baltensperger, Urs
    Zieger, Paul
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Schmale, Julia
    Frequent new particle formation over the high Arctic pack ice by enhanced iodine emissions2020Ingår i: Nature Communications, E-ISSN 2041-1723, Vol. 11, nr 1, artikel-id 4924Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the central Arctic Ocean the formation of clouds and their properties are sensitive to the availability of cloud condensation nuclei (CCN). The vapors responsible for new particle formation (NPF), potentially leading to CCN, have remained unidentified since the first aerosol measurements in 1991. Here, we report that all the observed NPF events from the Arctic Ocean 2018 expedition are driven by iodic acid with little contribution from sulfuric acid. Iodic acid largely explains the growth of ultrafine particles (UFP) in most events. The iodic acid concentration increases significantly from summer towards autumn, possibly linked to the ocean freeze-up and a seasonal rise in ozone. This leads to a one order of magnitude higher UFP concentration in autumn. Measurements of cloud residuals suggest that particles smaller than 30nm in diameter can activate as CCN. Therefore, iodine NPF has the potential to influence cloud properties over the Arctic Ocean. Which vapors are responsible for new particle formation in the Arctic is largely unknown. Here, the authors show that the formation of new particles at the central Arctic Ocean is mainly driven by iodic acid and that particles smaller than 30nm in diameter can activate as cloud condensation nuclei.

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  • 35. Bakovic, Vid
    et al.
    Höglund, Andrey
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap. Stockholms universitet, Science for Life Laboratory (SciLifeLab).
    Cerezo, Maria Luisa Martin
    Henriksen, Rie
    Wright, Dominic
    Genomic and gene expression associations to morphology of a sexual ornament in the chicken2022Ingår i: G3: Genes, Genomes, Genetics, E-ISSN 2160-1836, Vol. 12, nr 9, artikel-id jkac174Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    How sexual selection affects the genome ultimately relies on the strength and type of selection, and the genetic architecture of the involved traits. While associating genotype with phenotype often utilizes standard trait morphology, trait representations in morphospace using geometric morphometric approaches receive less focus in this regard. Here, we identify genetic associations to a sexual ornament, the comb, in the chicken system (Gallus gallus). Our approach combined genome-wide genotype and gene expression data (>30k genes) with different aspects of comb morphology in an advanced intercross line (F8) generated by crossing a wild-type Red Junglefowl with a domestic breed of chicken (White Leghorn). In total, 10 quantitative trait loci were found associated to various aspects of comb shape and size, while 1,184 expression QTL were found associated to gene expression patterns, among which 98 had overlapping confidence intervals with those of quantitative trait loci. Our results highlight both known genomic regions confirming previous records of a large effect quantitative trait loci associated to comb size, and novel quantitative trait loci associated to comb shape. Genes were considered candidates affecting comb morphology if they were found within both confidence intervals of the underlying quantitative trait loci and eQTL. Overlaps between quantitative trait loci and genome-wide selective sweeps identified in a previous study revealed that only loci associated to comb size may be experiencing on-going selection under domestication. 

  • 36. Balzer, Laura
    et al.
    Baptista-Salazar, Carluvy
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Jonsson, Sofi
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Biester, Harald
    Role of formation and decay of seston organic matter in the fate of methylmercury within the water column of a eutrophic lake2023Ingår i: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 20, nr 7, s. 1459-1472Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Anoxic microniches in sinking particles in lakes have been identified as important water phase production zones of monomethylmercury (MeHg). However, the production and decay of MeHg during organic matter (OM) decomposition in the water column and its relation to the total Hg concentration in seston are poorly understood. We investigated total Hg and MeHg in relation to chemical changes in sinking seston and hydrochemical settings in a small and shallow (12 m deep) eutrophic lake during phytoplankton blooms from April to November 2019. The results show that MeHg proportions reach up to 22 % in seston in oxygen super saturation at the water surface and highest values (up to 26 %) at the oxic–suboxic redox boundary. MeHg concentrations were highest in May and November when algal biomass production was low and seston were dominated by zooplankton. Biodilution of MeHg concentrations could not be observed in the months of the highest algal biomass production; instead, MeHg and THg concentrations in seston were comparatively high. During suboxic OM decomposition and with decreasing redox potential (Mn and nitrate reduction), the concentration and proportion of MeHg in seston strongly decreased (<0.5 %), whereas total Hg concentrations show a 3.8- to 26-fold increase with water depth. Here, it remains unclear to which extent biodilution on the one hand and OM decomposition on the other alter the MeHg and THg concentration in seston. Changes in OM quality were most intense within or slightly below the redox transition zone (RTZ). The concentrations of MeHg and THg in seston from the RTZ were comparable to those found in the sediment trap material which integrated the changes in seston composition during the entire sampling period, suggesting that changes in the MeHg and THg content in the hypolimnion below the RTZ are comparatively small. Our study suggests that, in shallow eutrophic lakes, the water phase formation and decomposition of MeHg is intense and controlled by the decomposition of algal biomass and is, assumedly, largely disconnected from Hg methylation in sediments, similar to what has been observed in deep oligotrophic lakes.

  • 37.
    Baptista-Salazar, Carluvy
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Liem-Nguyen, Van
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Jonsson, Sofi
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Experiments revealing the formation of refractory methylmercury pools in natural sediments and soils2022Ingår i: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 328, s. 76-84Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Methylation and demethylation of mercury (Hg) are well recognized as processes controlling the concentrations of monomethylmercury (MeHg) in natural environments, and thus the pool of Hg available for biological uptake. In addition, studies have indicated the potential role of refractory MeHg pools (not readily available for demethylation) on the pool of MeHg in, for example, sediments and soils. These studies, however, remain scarce and often the role of refractory MeHg pools is overlooked. Here, we have conducted incubation experiments aiming to quantify refractory MeHg pools in contrasting environments. In our study, sediments (from lakes and brackish seawater sites) and soils (from forests and marshes) were incubated with isotopically enriched Hg tracers (Me201Hg and 198Hg) for up to 6 weeks. To follow the potential formation of refractory MeHg pools, %MeHg (fraction of Hg occurring as MeHg) after the first week of incubation for the added 198Hg and Me201Hg tracers, and ambient Hg was compared. The high %MeHg for the 198Hg tracer compared to the %MeHg of ambient Hg suggests a higher initial availability of added 198Hg in comparison to the ambient Hg in the sediments. For the soils, low %MeHg for the 198Hg tracer suggests low Hg methylation rates. The discrepancy observed between the sediments and soils can be explained by a higher availability of inorganic Hg in the sediments, as suggested by the Hg thermal fractional analysis conducted. The %MeHg steady state for the added Me201Hg tracer remained high (>17%) throughout the experiment, suggesting refractory pools of MeHg to be built-up in all tested sediments and soils. Together, the %MeHg for the added Hg tracers demonstrate that a significant fraction of the MeHg produced in sediments and soils is sequestered into refractory pools not readily available for demethylation. Furthermore, these results show that conditions favoring net methylation in sediments and soil could result in elevated concentrations of MeHg for a significant amount of time (months) even if the conditions favoring Hg net methylation are only temporary.

  • 38.
    Baptista-Salazar, Carluvy
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Quadra, Gabrielle R.
    Sobek, Anna
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Jonsson, Sofi
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Insights into the factors influencing mercury concentrations in tropical reservoir sediments2021Ingår i: Environmental Science: Processes & Impacts, ISSN 2050-7887, E-ISSN 2050-7895, Vol. 23, nr 10, s. 1542-1553Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Thousands of dams are currently under construction or planned worldwide to meet the growing need for electricity. The creation of reservoirs could, however, lead to conditions that promote the accumulation of mercury (Hg) in surface sediments and the subsequent production of methylmercury (MeHg). Once produced, MeHg can bioaccumulate to harmful levels in organisms. It is unclear to what extent variations in physical features and biogeochemical factors of the reservoir impact Hg accumulation. The objective of this study was to identify key drivers of the accumulation of total Hg (THg) in tropical reservoir sediments. The concentration of THg in all analyzed depth intervals of 22 sediment cores from the five contrasting reservoirs investigated ranged from 16 to 310 ng g(-1) (n = 212, in the different sediment cores, the maximum depth varied from 18 to 96 cm). Our study suggests reservoir size to be an important parameter determining the concentration of THg accumulating in tropical reservoir sediments, with THg ranging up to 50 ng g(-1) in reservoirs with an area exceeding 400 km(2) and from 100 to 200 ng g(-1) in reservoirs with an area less than 80 km(2). In addition to the reservoir size, the role of land use, nutrient loading, biome and sediment properties (e.g., organic carbon content) was tested as potential drivers of THg levels. The principal component analysis conducted suggested THg to be related to the properties of the watershed (high degree of forest cover and low degree of agricultural land use), size and age of the reservoir, water residence time and the levels of nutrients in the reservoir. A direct correlation between THg and tested variables was, however, only observed with the area of the reservoir.

  • 39.
    Bardakov, Roman
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Meteorologiska institutionen (MISU). Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI).
    Krejci, Radovan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI).
    Riipinen, Ilona
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap. Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI).
    Ekman, Annica M. L.
    Stockholms universitet, Naturvetenskapliga fakulteten, Meteorologiska institutionen (MISU). Stockholms universitet, Naturvetenskapliga fakulteten, Bolincentret för klimatforskning (tills m KTH & SMHI).
    The Role of Convective Up- and Downdrafts in the Transport of Trace Gases in the Amazon2022Ingår i: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 127, nr 18, artikel-id e2022JD037265Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Deep convective clouds can redistribute gaseous species and particulate matter among different layers of the troposphere with important implications for atmospheric chemistry and climate. The large number of atmospheric trace gases of different volatility makes it challenging to predict their partitioning between hydrometeors and gas phase inside highly dynamic deep convective clouds. In this study, we use an ensemble of 51,200 trajectories simulated with a cloud-resolving model to characterize up- and downdrafts within Amazonian deep convective clouds. We also estimate the transport of a set of hypothetical non-reactive gases of different volatility, within the up- and downdrafts. We find that convective air parcels originating from the boundary layer (i.e., originating at 0.5 km altitude), can transport up to 25% of an intermediate volatility gas species (e.g., methyl hydrogen peroxide) and up to 60% of high volatility gas species (e.g., n-butane) to the cloud outflow above 10 km through the mean convective updraft. At the same time, the same type of gases can be transported to the boundary layer from the middle troposphere (i.e., originating at 5 km) within the mean convective downdraft with an efficiency close to 100%. Low volatility gases (e.g., nitric acid) are not efficiently transported, neither by the updrafts nor downdrafts, if the gas is assumed to be fully retained in a droplet upon freezing. The derived properties of the mean up- and downdraft can be used in future studies for investigating convective transport of a larger set of reactive trace gases.

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  • 40.
    Bardakov, Roman
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Meteorologiska institutionen (MISU).
    Krejci, Radovan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Riipinen, Ilona
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Ekman, Annica M. L.
    Stockholms universitet, Naturvetenskapliga fakulteten, Meteorologiska institutionen (MISU).
    Vertical redistribution of air and trace gases within deep convective clouds over the Amazon: a statistical analysis based on a trajectory ensembleManuskript (preprint) (Övrigt vetenskapligt)
  • 41.
    Bardakov, Roman
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Meteorologiska institutionen (MISU).
    Riipinen, Ilona
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Krejci, Radovan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Savre, Julien
    Thornton, Joel A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Meteorologiska institutionen (MISU). University of Washington, USA.
    Ekman, Annica M. L.
    Stockholms universitet, Naturvetenskapliga fakulteten, Meteorologiska institutionen (MISU).
    A Novel Framework to Study Trace Gas Transport in Deep Convective Clouds2020Ingår i: Journal of Advances in Modeling Earth Systems, ISSN 1942-2466, Vol. 12, nr 5, artikel-id e2019MS001931Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Deep convective clouds reach the upper troposphere (8-15 km height). In addition to moisture and aerosol particles, they can bring aerosol precursor gases and other reactive trace gases from the planetary boundary layer to the cloud top. In this paper, we present a method to estimate trace gas transport based on the analysis of individual air parcel trajectories. Large eddy simulation of an idealized deep convective cloud was used to provide realistic environmental input to a parcel model. For a buoyant parcel, we found that the trace gas transport approximately follows one out of three scenarios, determined by a combination of the equilibrium vapor pressure (containing information about water-solubility and pure component saturation vapor pressure) and the enthalpy of vaporization. In one extreme, the trace gas will eventually be completely removed by precipitation. In the other extreme, there is almost no vapor condensation on hydrometeors and most of the gas is transported to the top of the cloud. The scenario in between these two extremes is also characterized by strong gas condensation, but a small fraction of the trace gas may still be transported aloft. This approach confirms previously suggested patterns of inert trace gas behavior in deep convective clouds, agrees with observational data, and allows estimating transport in analytically simple and computationally efficient way compared to explicit cloud-resolving model calculations.

  • 42.
    Bardakov, Roman
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Meteorologiska institutionen (MISU).
    Thornton, Joel A.
    Riipinen, Ilona
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Krejci, Radovan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Ekman, Annica M. L.
    Stockholms universitet, Naturvetenskapliga fakulteten, Meteorologiska institutionen (MISU).
    Transport and chemistry of isoprene and its oxidation products in deep convective clouds2021Ingår i: Tellus. Series B, Chemical and physical meteorology, ISSN 0280-6509, E-ISSN 1600-0889, Vol. 73, nr 1, s. 1-21Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Deep convective clouds can transport trace gases from the planetary boundary layer into the upper troposphere where subsequent chemistry may impact aerosol particle formation and growth. In this modelling study, we investigate processes that affect isoprene and its oxidation products injected into the upper troposphere by an isolated deep convective cloud in the Amazon. We run a photochemical box model with coupled cloud microphysics along hundreds of individual air parcel trajectories sampled from a cloud-resolving model simulation of a convective event. The box model simulates gas-phase chemical reactions, gas scavenging by liquid and ice hydrometeors, and turbulent dilution inside a deep convective cloud. The results illustrate the potential importance of gas uptake to anvil ice in regulating the intensity of the isoprene oxidation and associated low volatility organic vapour concentrations in the outflow. Isoprene transport and fate also depends on the abundance of lightning-generated nitrogen oxide radicals (NOx = NO + NO2). If gas uptake on ice is efficient and lightning activity is low, around 30% of the boundary layer isoprene will survive to the cloud outflow after approximately one hour of transport, while all the low volatile oxidation products will be scavenged by the cloud hydrometeors. If lightning NOx is abundant and gas uptake by ice is inefficient, then all isoprene will be oxidised during transport or in the immediate outflow region, while several low volatility isoprene oxidation products will have elevated concentrations in the cloud outflow. Reducing uncertainties associated with the uptake of vapours on ice hydrometeors, especially HO2 and oxygenated organics, is essential to improve predictions of isoprene and its oxidation products in deep convective outflows and their potential contribution to new particle formation and growth.

  • 43. Barouki, Robert
    et al.
    Kogevinas, Manolis
    Audouze, Karine
    Belesova, Kristine
    Bergman, Åke
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Birnbaum, Linda
    Boekhold, Sandra
    Denys, Sebastien
    Desseille, Celine
    Drakvik, Elina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Frumkin, Howard
    Garric, Jeanne
    Destoumieux-Garzon, Delphine
    Haines, Andrew
    Huss, Anke
    Jensen, Genon
    Karakitsios, Spyros
    Klanova, Jana
    Koskela, Iida-Maria
    Laden, Francine
    Marano, Francelyne
    Matthies-Wiesler, Eva Franziska
    Morris, George
    Nowacki, Julia
    Paloniemi, Riikka
    Pearce, Neil
    Peters, Annette
    Rekola, Aino
    Sarigiannis, Denis
    Šebková, Katerinaa
    Slama, Remy
    Staatsen, Brigit
    Tonne, Cathryn
    Vermeulen, Roel
    Vineis, Paolo
    The COVID-19 pandemic and global environmental change: Emerging research needs2021Ingår i: Environment International, ISSN 0160-4120, E-ISSN 1873-6750, Vol. 146, artikel-id 106272Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The outbreak of COVID-19 raised numerous questions on the interactions between the occurrence of new infections, the environment, climate and health. The European Union requested the H2020 HERA project which aims at setting priorities in research on environment, climate and health, to identify relevant research needs regarding Covid-19. The emergence and spread of SARS-CoV-2 appears to be related to urbanization, habitat destruction, live animal trade, intensive livestock farming and global travel. The contribution of climate and air pollution requires additional studies. Importantly, the severity of COVID-19 depends on the interactions between the viral infection, ageing and chronic diseases such as metabolic, respiratory and cardiovascular diseases and obesity which are themselves influenced by environmental stressors. The mechanisms of these interactions deserve additional scrutiny. Both the pandemic and the social response to the disease have elicited an array of behavioural and societal changes that may remain long after the pandemic and that may have long term health effects including on mental health. Recovery plans are currently being discussed or implemented and the environmental and health impacts of those plans are not clearly foreseen. Clearly, COVID-19 will have a longlasting impact on the environmental health field and will open new research perspectives and policy needs.

  • 44. Beck, Lisa J.
    et al.
    Sarnela, Nina
    Junninen, Heikki
    Hoppe, Clara J. M.
    Garmash, Olga
    Bianchi, Federico
    Riva, Matthieu
    Rose, Clemence
    Peräkylä, Otso
    Wimmer, Daniela
    Kausiala, Oskari
    Jokinen, Tuija
    Ahonen, Lauri
    Mikkilä, Jyri
    Hakala, Jani
    He, Xu-Cheng
    Kontkanen, Jenni
    Wolf, Klara K. E.
    Cappelletti, David
    Mazzola, Mauro
    Traversi, Rita
    Petroselli, Chiara
    Viola, Angelo P.
    Vitale, Vito
    Lange, Robert
    Massling, Andreas
    Nøjgaard, Jakob K.
    Krejci, Radovan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Karlsson, Linn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Zieger, Paul
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Jang, Sehyun
    Lee, Kitack
    Vakkari, Ville
    Lampilahti, Janne
    Thakur, Roseline C.
    Leino, Katri
    Kangasluoma, Juha
    Duplissy, Ella-Maria
    Siivola, Erkki
    Marbouti, Marjan
    Tham, Yee Jun
    Saiz-Lopez, Alfonso
    Petäjä, Tuukka
    Ehn, Mikael
    Worsnop, Douglas R.
    Skov, Henrik
    Kulmala, Markku
    Kerminen, Veli-Matti
    Sipilä, Mikko
    Differing Mechanisms of New Particle Formation at Two Arctic Sites2021Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 48, nr 4, artikel-id e2020GL091334Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    New particle formation in the Arctic atmosphere is an important source of aerosol particles. Understanding the processes of Arctic secondary aerosol formation is crucial due to their significant impact on cloud properties and therefore Arctic amplification. We observed the molecular formation of new particles from low-volatility vapors at two Arctic sites with differing surroundings. In Svalbard, sulfuric acid (SA) and methane sulfonic acid (MSA) contribute to the formation of secondary aerosol and to some extent to cloud condensation nuclei (CCN). This occurs via ion-induced nucleation of SA and NH3 and subsequent growth by mainly SA and MSA condensation during springtime and highly oxygenated organic molecules during summertime. By contrast, in an ice-covered region around Villum, we observed new particle formation driven by iodic acid but its concentration was insufficient to grow nucleated particles to CCN sizes. Our results provide new insight about sources and precursors of Arctic secondary aerosol particles.

  • 45. Been, Frederic
    et al.
    Kruve, Anneli
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Vughs, Dennis
    Meekel, Nienke
    Reus, Astrid
    Zwartsen, Anne
    Wessel, Arnoud
    Fischer, Astrid
    Ter Laak, Thomas
    Brunner, Andrea M.
    Risk-based prioritization of suspects detected in riverine water using complementary chromatographic techniques2021Ingår i: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 204, artikel-id 117612Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Surface waters are widely used as drinking water sources and hence their quality needs to be continuously monitored. However, current routine monitoring programs are not comprehensive as they generally cover only a limited number of known pollutants and emerging contaminants. This study presents a risk-based approach combining suspect and non-target screening (NTS) to help extend the coverage of current monitoring schemes. In particular, the coverage of NTS was widened by combining three complementary separations modes: Reverse phase (RP), Hydrophilic interaction liquid chromatography (HILIC) and Mixed-mode chromatography (MMC). Suspect lists used were compiled from databases of relevant substances of very high concern (e.g., SVHCs) and the concentration of detected suspects was evaluated based on ionization efficiency prediction. Results show that suspect candidates can be prioritized based on their potential risk (i.e., hazard and exposure) by combining ionization efficiency-based concentration estimation, in vitro toxicity data or, if not available, structural alerts and QSAR.based toxicity predictions. The acquired information shows that NTS analyses have the potential to complement target analyses, allowing to update and adapt current monitoring programs, ultimately leading to improved monitoring of drinking water sources.

  • 46. Bell, David M.
    et al.
    Wu, Cheng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Bertrand, Amelie
    Graham, Emelie
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Schoonbaert, Janne
    Giannoukos, Stamatios
    Baltensperger, Urs
    Prevot, Andre S. H.
    Riipinen, Ilona
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    El Haddad, Imad
    Mohr, Claudia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Particle-phase processing of α-pinene NO3 secondary organic aerosol in the dark2022Ingår i: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 22, nr 19, s. 13167-13182Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The NO3 radical represents a significant night-time oxidant present in or downstream of polluted environments. There are studies that investigated the formation of secondary organic aerosol (SOA) from NO3 radicals focusing on yields, general composition, and hydrolysis of organonitrates. However, there is limited knowledge about how the composition of NO3-derived SOA evolves as a result of particle phase reactions. Here, SOA was formed from the reaction of α-pinene with NO3 radicals generated from N2O5, and the resulting SOA aged in the absence of external stimuli. The initial composition of NO3-derived α-pinene SOA was slightly dependent upon the concentration of N2O5 injected (excess of NO3 or excess of α-pinene), but was largely dominated by dimer dinitrates (C20H32N2O8-13). Oxidation reactions (e.g. C20H32N2O8 → C20H32N2O9 → C20H32N2O10 etc...) accounted for 60–70 % of the particle phase reactions observed. Fragmentation reactions and dimer degradation pathways made up the remainder of the particle-phase processes occurring. The exact oxidant is not known, though suggestions are offered (e.g. N2O5, organic peroxides, or peroxy-nitrates). Hydrolysis of −ONO2 functional groups was not an important loss term during dark aging under the relative humidity conditions of our experiments (58–62 %), and changes in the bulk organonitrate composition were likely driven by evaporation of highly nitrogenated molecules. Overall, 25–30 % of the particle-phase composition changes as a function of particle-phase reactions during dark aging representing an important atmospheric aging pathway.

  • 47. Benavente, Veronica
    et al.
    Lage, Sandra
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap. Swedish University of Agricultural Sciences, Sweden.
    Gentili, Francesco G.
    Jansson, Stina
    Influence of lipid extraction and processing conditions on hydrothermal conversion of microalgae feedstocks - Effect on hydrochar composition, secondary char formation and phytotoxicity2022Ingår i: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 428, artikel-id 129559Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study investigated the effect of lipid extraction of microalgae feedstocks subjected to hydrothermal carbonization (HTC) with regard to the carbonization degree, chemical composition and phytotoxicity of hydrochars produced under different reaction temperatures and residence times. Special attention was given to the formation and composition of secondary char, as this part of the hydrochar may be of particular importance for environmental and technical applications. A microalgae polyculture grown in municipal wastewater was extracted to retrieve lipids, and both unextracted (MA) and extracted microalgae (EMA) were used to produce hydrochars at 180-240 degrees C for 1-4 h. The composition of the hydrochars was thoroughly characterized by elemental analysis, thermogravimetric analysis and pyrolysis-gas chromatography/mass spectrometry analysis. MA exhibited a greater carbonization degree than EMA and contained higher amounts of secondary char under the same processing conditions. During the carbonization of EMA, more decomposition products remained in the liquid phase and less polymerization occurred than for MA, which explained the lower solid yield of EMA-derived hydrochars in comparison to MA hydrochars. Consequently, although they contained potentially toxic substances (i.e., carboxylic acids, aldehydes and ketones), the EMA-derived hydrochars exhibited a lower phytotoxic potential. This indicates that low-temperature hydrochars containing less than 10% of extractives might be suitable as soil amendments, whereas extractive-rich hydrochars would be more appropriate for other long-term applications, such as adsorbents for contaminant removal, energy storage and composite materials. Detailed characterization of microalgae-derived hydrochars is required to enable the most suitable application areas to be identified for these materials, and thereby make full use of their function as carbon sinks.

  • 48.
    Berggren, Louise
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Investigating sources of per-and polyfluoroalkyl substances (PFAS) to Lake Mälaren: A Master's thesis in collaboration with NIRAS2023Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Per- and polyfluoroalkyl substances (PFAS) are among the most problematic classes of contemporary chemicals known to exist. PFAS can be found in even the most remote places around the world, including in the blood of humans and wildlife. The extreme stability of PFAS has led to the use of these chemicals in a wide variety of products. However, the same qualities which make these chemicals stable, also make them environmentally persistent. This thesis aimed to investigate possible sources of PFAS in Ekerö, Järfälla and Stockholm, Sweden and their contribution to overall PFAS levels in Lake Mälaren. Lake Mälaren is a major provider of drinking water to the citizens of Stockholm. The investigation was a joint effort between Norrvatten, Stockholm Vatten och Avfall (SVOA), Ekerö municipality, Järfälla municipality, Stockholm city together with the consulting firm NIRAS. PFAS occurred in varying levels found at each location (0,34-371 ng/L sum of PFAS 21). In general, the three most prevalent PFAS were perfluoropentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA) and 6:2 fluorotelomer sulfonic acid (6:2 FTS). Concentrations at several sites exceeded guideline values proposed by the European Union which go into force in 2026 regarding PFAS in drinking water. The location with the highest output into Lake Mälaren was Råcksta in Stockholm with an output of 11304,44 µg/year. None of the sites contributed significantly.  

  • 49. Berglund, asa M. M.
    et al.
    Gallampois, Christine
    Ripszam, Matyas
    Larsson, Henrik
    Figueroa, Daniela A.
    Griniene, Evelina
    Bystrom, Paer
    Gorokhova, Elena
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik. Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Haglund, Peter
    Andersson, Agneta
    Tysklind, Mats
    Effects on the food-web structure and bioaccumulation patterns of organic contaminants in a climate-altered Bothnian Sea mesocosms2023Ingår i: Frontiers in Marine Science, E-ISSN 2296-7745, Vol. 10, artikel-id 1244434Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Climate change is expected to alter global temperature and precipitation patterns resulting in complex environmental impacts. The proposed higher precipitation in northern Scandinavia would increase runoff from land, hence increase the inflow of terrestrial dissolved organic matter (tDOM) in coastal regions. This could promote heterotrophic bacterial production and shift the food web structure, by favoring the microbial food web. The altered climate is also expected to affect transport and availability of organic micropollutants (MPs), with downstream effects on exposure and accumulation in biota. This study aimed to assess climate-induced changes in a Bothnian Sea food web structure as well as bioaccumulation patterns of MPs. We performed a mesocosms-study, focusing on aquatic food webs with fish as top predator. Alongside increased temperature, mesocosm treatments included tDOM and MP addition. The tDOM addition affected nutrient availability and boosted both phytoplankton and heterotrophic bacteria in our fairly shallow mesocosms. The increased tDOM further benefitted flagellates, ciliates and mesozooplankton, while the temperature increase and MP addition had minor effect on those organism groups. Temperature, on the other hand, had a negative impact on fish growth and survival, whereas tDOM and MP addition only had minor impact on fish. Moreover, there were indications that bioaccumulation of MPs in fish either increased with tDOM addition or decreased at higher temperatures. If there was an impact on bioaccumulation, moderately lipophilic MPs (log Kow 3.6 - 4.6) were generally affected by tDOM addition and more lipophilic MPs (log Kow 3.8 to 6.4) were generally affected by increased temperature. This study suggest that both increased temperatures and addition of tDOM likely will affect bioaccumulation patterns of MPs in shallow coastal regions, albeit with counteracting effects.

  • 50. Betterle, Andrea
    et al.
    Jaeger, Anna
    Posselt, Malte
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Coll, Claudia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap. Swiss Federal Institute of Aquatic Science and Technology, Switzerland.
    Benskin, Jonathan P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap.
    Schirmer, Mario
    Hyporheic exchange in recirculating flumes under heterogeneous bacterial and morphological conditions2021Ingår i: Environmental Earth Sciences, ISSN 1866-6280, E-ISSN 1866-6299, Vol. 80, nr 6, artikel-id 234Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hyporheic exchange (HE) contributes to the biogeochemical turnover of macro- and micro-pollutants in rivers. However, the spatiotemporal complexity and variability of HE hinder understanding of its role in the overall functioning of riverine ecosystems. The present study focuses on investigating the role of bacterial diversity and sediment morphology on HE using a multi-flume experiment. A fully coupled surface–subsurface numerical model was used to highlight complex exchange patterns between surface water and the underlying flow field in the sediments. Under the experimental conditions, the surface water flow induced by bedforms has a prominent effect on both local trajectories and residence time distributions of hyporheic flow paths, whereas mean hyporheic retention times are mainly modulated by average surface flowrates. In case of complex bedform morphologies, the numerical model successfully reproduces the HE estimated by means of salt dilution tests. However, the 2D numerical representation of the system falls short in predicting HE in absence of bedforms, highlighting the intrinsic complexity of water circulation patterns in real scenarios. Finally, results show that higher bacterial diversities in the stream sediments can significantly reduce hyporheic fluxes. This work provides a framework to interpret micropollutants turnover in light of the underlying physical transport processes in the hyporheic zone. The study emphasizes the importance of better understanding the tradeoff between physically driven transport processes and bacterial dynamics in the hyporheic zone to quantify the fate of pollutants in streams and rivers.

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