| 1. |
- Praetorius, A., et al.
(författare)
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Strategies for determining heteroaggregation attachment efficiencies of engineered nanoparticles in aquatic environments
- 2020
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Ingår i: Environmental Science-Nano. - : Royal Society of Chemistry (RSC). - 2051-8153 .- 2051-8161. ; 7:2, s. 351-367
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Tidskriftsartikel (refereegranskat)abstract
- Heteroaggregation of engineered nanoparticles (ENPs) with suspended particulate matter (SPM) ubiquitous in natural waters often dominates the transport behaviour and overall fate of ENPs in aquatic environments. In order to provide meaningful exposure predictions and support risk assessment for ENPs, environmental fate and transport models require quantitative information about this process, typically in the form of the so-called attachment efficiency for heteroaggregation alpha(hetero). The inherent complexity of heteroaggregation-encompassing at least two different particle populations, various aggregation pathways and several possible attachment efficiencies (alpha values)-makes its theoretical and experimental determination challenging. In this frontier review we assess the current state of knowledge on heteroaggregation of ENPs with a focus on natural surface waters. A theoretical analysis presents relevant equations, outlines the possible aggregation pathways and highlights different types of alpha. In a second part, experimental approaches to study heteroaggregation and derive alpha values are reviewed and three possible strategies are identified: i) monitoring changes in size, ii) monitoring number or mass distribution and iii) studying indirect effects, such as sedimentation. It becomes apparent that the complexity of heteroaggregation creates various challenges and no single best method for its assessment has been developed yet. Nevertheless, many promising strategies have been identified and meaningful data can be derived from carefully designed experiments when accounting for the different concurrent aggregation pathways and clearly stating the type of alpha reported. For future method development a closer connection between experiments and models is encouraged.
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| 2. |
- Ribeiro, F., et al.
(författare)
-
Silver nanoparticles and silver nitrate induce high toxicity to Pseudokirchneriella subcapitata, Daphnia magna and Danio rerio
- 2014
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697. ; 466, s. 232-241
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Tidskriftsartikel (refereegranskat)abstract
- Silver nanoparticles (AgNP) have gained attention over the years due to the antimicrobial function of silver, which has been exploited industrially to produce consumer goods that vary in type and application. Undoubtedly the increase of production and consumption of these silver-containing products will lead to the entry of silver compounds into the environment. In this study we have used Pseudokirchneriella subcapitata, Daphnia magna and Danio rerio as model organisms to investigate the toxicity of AgNP and AgNO3 by assessing different biological endpoints and exposure periods. Organisms were exposed following specific and standardized protocols for each species/endpoints, with modifications when necessary. AgNP were characterized in each test-media by Transmission Electron Microscopy (TEM) and experiments were performed by Dynamic Light Scattering (DIS) to investigate the aggregation and agglomeration behavior of AgNP under different media chemical composition and test-period. TEM images of AgNP in the different test-media showed dissimilar patterns of agglomeration, with some agglomerates inside an organic layer, some loosely associated particles and also the presence of some individual particles. The toxicity of both AgNO3 and AgNP differ significantly based on the test species: we found no differences in toxicity for algae, a small difference for zebrafish and a major difference in toxicity for Daphnia magna, (C) 2013 Elsevier B.V. All rights reserved.
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| 3. |
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| 4. |
- Calisi, A., et al.
(författare)
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Ecotoxicological effects of silver nanoparticles in marine mussels
- 2022
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697. ; 851
-
Tidskriftsartikel (refereegranskat)abstract
- As the production of silver nanoparticles (AgNPs) is becoming more prevalent, it is becoming increasingly necessary to understand the toxicological effects they can have on different ecosystems. In the marine bioindicator species M. galloprovincialis Lam we predicted toxicity and bioaccumulation of 5 nm alkane-coated and 50 nm uncoated silver nanoparticles (AgNPs) along with silver nitrate as a function of the actual dose level. We generated a time persistence model of silver in seawater and used the Area Under the Curve (AUC) as independent variable in the hazard assessment. This approach allowed us to evaluate unbiased ecotoxicological endpoints for acute (survival) and chronic toxicity (byssal adhesion). Logistic regression analysis rendered an overall LC5096h values of 0.81 & PLUSMN; 0.07 mg h L-1 irrespectively of the silver form. By contrast, for byssal adhesion regression analysis revealed a much higher toxicological potential of silver nitrate vs AgNPs with EC5024h values respectively of 0.0024 & PLUSMN; 0.0009 vs 0.053 & PLUSMN; 0.016 and 0.063 (no computable error for 50 nm AgNP) mg h L-1, undoubtedly confirming a prevalence of ionic silver effects over AgNPs. Bioaccumulation was more efficient for silver nitrate > 5 nm AgNP > 50 nm AgNP reflecting a parallel with the prefer-ential uptake route / target organ. Finally, we derived Risk Quotient (RQs) for acute and chronic effects of nanosilver in shellfish and showed that the RQs are far from the Level of Concern (LoC) at current estimated environmental concentrations (EECs). This information can ultimately help researchers, policy makers, and industry professionals decide how to safely regulate and/or dis-pose of AgNPs.
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| 5. |
- Danielsson, Karin, et al.
(författare)
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Effects of the adsorption of NOM model molecules on the aggregation of TiO2 nanoparticles in aqueous suspensions
- 2018
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Ingår i: NanoImpact. - : Elsevier BV. - 2452-0748. ; 10, s. 177-187
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Tidskriftsartikel (refereegranskat)abstract
- © 2018 Interaction of synthetic TiO2(anatase) nanoparticles in aqueous suspension at pH 5 was investigated as a function of time in the presence of various organic molecules in terms of adsorption and aggregation behaviour. ζ-potential and average particle diameter were determined with electrophoretic and dynamic light scattering, respectively, while batch adsorption experiments were used to quantify the amount of organic ligand adsorbed to the TiO2NP. An IR spectroscopic study was carried out at pH 2.8 and 5 to gain information about the interactions of the adsorbed molecules with the TiO2surface on the molecular level. Furthermore, DLVO calculations provided information about the interaction energies between particles and their tendency to aggregate under some experimental conditions. Colloidal stability of TiO2NPs in the presence of organic molecules was studied during a time period of up to 90 days. Results showed that ligands with different functional groups may interact differently with the surface depending on the type and position of available surface sites, the molecular structure of the ligand and suspension pH. Adsorption, hydrodynamic diameter and ζ-potential were affected by the ligand concentration in all tested systems. Increased concentration gave rise to increased adsorption, while ζ-potential decreased and charge inversion was observed for all tested molecules at pH 5. IR spectroscopic study showed the formation of inner sphere and/or outer sphere complexes depending on pH and type of organic ligand. According to DLVO calculations, the critical coagulation concentration (CCC) indicated a trend of increasing colloidal stability with increased concentration of SRFA at pH 5, which was in agreement with the experimental data.
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| 6. |
- Danielsson, Karin, et al.
(författare)
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Influence of organic molecules on the aggregation of TiO2 nanoparticles in acidic conditions
- 2017
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Ingår i: Journal of nanoparticle research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 19
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Tidskriftsartikel (refereegranskat)abstract
- © 2017, The Author(s).Engineered nanoparticles released into the environment may interact with natural organic matter (NOM). Surface complexation affects the surface potential, which in turn may lead to aggregation of the particles. Aggregation of synthetic TiO2 (anatase) nanoparticles in aqueous suspension was investigated at pH 2.8 as a function of time in the presence of various organic molecules and Suwannee River fulvic acid (SRFA), using dynamic light scattering (DLS) and high-resolution transmission electron microscopy (TEM). Results showed that the average hydrodynamic diameter and ζ-potential were dependent on both concentration and molecular structure of the organic molecule. Results were also compared with those of quantitative batch adsorption experiments. Further, a time study of the aggregation of TiO2 nanoparticles in the presence of 2,3-dihydroxybenzoic acid (2,3-DHBA) and SRFA, respectively, was performed in order to observe changes in ζ-potential and particle size over a time period of 9months. In the 2,3-DHBA-TiO2 system, ζ-potentials decreased with time resulting in charge neutralization and/or inversion depending on ligand concentration. Aggregate sizes increased initially to the micrometer size range, followed by disaggregation after several months. No or very little interaction between SRFA and TiO2 occurred at the lowest concentrations tested. However, at the higher concentrations of SRFA, there was an increase in both aggregate size and the amount of SRFA adsorbed to the TiO2 surface. This was in correlation with the ζ-potential that decreased with increased SRFA concentration, leading to destabilization of the system. These results stress the importance of performing studies over both short and long time periods to better understand and predict the long-term effects of nanoparticles in the environment.
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| 7. |
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| 8. |
- Gallego-Urrea, Julian A., 1977, et al.
(författare)
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Influence of different types of natural organic matter on titania nanoparticle stability: effects of counter ion concentration and pH
- 2014
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Ingår i: Environmental Science-Nano. - : Royal Society of Chemistry (RSC). - 2051-8153. ; 1:2, s. 181-189
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Tidskriftsartikel (refereegranskat)abstract
- The effects of biopolymeric (alginate) and refractory macromolecules (humic and fulvic acids) on the aggregation kinetics of anatase titanium dioxide (titania) nanoparticles were evaluated. The particles were synthesized using a wet-chemical method based on the hydrolysis of TiCl4. Stable suspensions of positively-charged titania were obtained at pH 2.5. One batch of this product was shifted above the point of zero charge to pH 12. These dispersions were mixed with three different types of well characterized environmental macromolecules: sodium alginate, fulvic acid and humic acid, and evaluated in terms of the stability. Changes in the particle size were measured using time-resolved dynamic light scattering (TR-DLS) at different concentrations of three electrolytes: NaCl, CaCl2 and Na2SO4, and at different solution pH values. Results were in agreement with DLVO calculations. The use of TR-DLS for determining aggregation rates is critically discussed.
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| 9. |
- Kleiven, Merethe, et al.
(författare)
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Characterizing the behavior, uptake, and toxicity of NM300K silver nanoparticles in Caenorhabditis elegans
- 2018
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Ingår i: Environmental Toxicology and Chemistry. - : Wiley. - 0730-7268 .- 1552-8618. ; 37:7, s. 1799-1810
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Tidskriftsartikel (refereegranskat)abstract
- © 2018 SETAC. Using Caenorhabditis elegans as a model organism, we addressed the potential linkage among toxicity of NM300K Ag nanoparticles (AgNPs), their particle size distribution, and the presence of dissolved Ag in the test media. Of the 3 endpoints assessed (growth, fertility, and reproduction), reproduction was the most sensitive, with the 50% effect concentration (EC50) ranging from 0.26 to 0.84mgAgL -1 and 0.08 to 0.11mgAgL -1 for NM300K and AgNO 3 , respectively. Silver uptake by C. elegans was similar for both forms of Ag, whereas bioaccumulation was higher in AgNO 3 exposure. The observed differences in toxicity between NM300K and AgNO 3 did not correlate with bioaccumulated Ag, which suggests that toxicity is a function of the type of exposing agent (AgNPs vs AgNO 3 ) and its mode of action. Before addition of the food source (Escherichia coli), size fractionation revealed that dissolved Ag comprised 13 to 90% and 4 to 8% of total Ag in the AgNO 3 and NM300K treatments, respectively. No dissolved Ag was detectable in the actual test media due to immediate Ag adsorption to bacteria. The results of the present study indicate that information on behavior and characterization of exposure conditions is essential for nanotoxicity studies.
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| 10. |
- Nowack, Bernd, et al.
(författare)
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Potential scenarios for nanomaterial release and subsequent alteration in the environment
- 2012
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Ingår i: Environmental Toxicology and Chemistry. - : Wiley. - 0730-7268 .- 1552-8618. ; 31:1, s. 50-59
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Tidskriftsartikel (refereegranskat)abstract
- The risks associated with exposure to engineered nanomaterials (ENMs) will be determined in part by the processes that control their environmental fate and transformation. These processes act not only on ENMs that might be released directly into the environment, but more importantly also act on ENMs in consumer products and those that have been released from the product. The environmental fate and transformation is likely to differ significantly for each of these cases. The ENM released from actual direct use or from nano-containing products are much more relevant for ecotoxicological studies and risk assessment than pristine ENMs. The released ENMs may have a greater or lesser environmental impact than the starting materials, depending on the transformation reactions and the material. Almost nothing is known about the environmental behavior and the effects of released and transformed ENMs, although these are the materials that are actually present in the environment. Further research is needed to show if the release and transformation processes result in a similar or more diverse set of ENMs and ultimately how this affects environmental behavior. These questions are addressed in this article using four brief hypothetical case studies that cover a wide range of ENMs, their direct use or product applications, and their likely fate in the environment. Furthermore, a more definitive classification scheme for ENMs should be adopted that reflects their surface condition, which is a result of both industrial and environmental processes acting on the ENM. The authors conclude that it is not possible to assess the risks associated with the use of ENMs by investigating only the naked (pristine) form of the ENM, without considering alterations and transformation processes. Environ. Toxicol. Chem. © 2011 SETAC.
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| 11. |
- Ribeiro, F., et al.
(författare)
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Uptake and elimination kinetics of silver nanoparticles and silver nitrate by Raphidocelis subcapitata: The influence of silver behaviour in solution
- 2015
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Ingår i: Nanotoxicology. - : Informa UK Limited. - 1743-5390 .- 1743-5404. ; 9:6, s. 686-695
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Tidskriftsartikel (refereegranskat)abstract
- Raphidocelis subcapitata is a freshwater algae species that constitutes the basis of many aquatic trophic chains. In this study, R. subcapitata was used as a model species to investigate the kinetics of uptake and elimination of silver nanoparticles (AgNP) in comparison to silver nitrate (AgNO3) with particular focus on the Ag sized-fractions in solution. AgNP used in this study were provided in a suspension of 1mg Ag/l, with an initial size of 3-8nm and coated with an alkane material. Algae was exposed for 48 h to both AgNP and AgNO3 and sampled at different time points to determine their internal Ag concentration over time. Samples were collected and separated into different sized fractions: total (Ag-tot), water column Ag (Ag-water), small particulate Ag (Ag-small.part.) and dissolved Ag (Ag-dis). At AgNO3 exposures algae reached higher bioconcentration factor (BCF) and lower elimination rate constants than at AgNP exposures, meaning that Ag is more readily taken up by algae in its dissolved form than in its small particulate form, however slowly eliminated. When modelling the kinetics based on the Ag-dis fraction, a higher BCF was found. This supports our hypothesis that Ag would be internalised by algae only in its dissolved form. In addition, algae images obtained by Coherent Anti-stokes Raman Scattering (CARS) microscopy demonstrated large aggregates of nanoparticles external to the algae cells with no evidence of its internalisation, thus providing a strong suggestion that these AgNP were not able to penetrate the cells and Ag accumulation happens through the uptake of Ag ions.
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| 12. |
- Tuoriniemi, Jani, 1982, et al.
(författare)
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Intermethod comparison of the particle size distributions of colloidal silica nanoparticles
- 2014
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Ingår i: Science and Technology of Advanced Materials. - : Informa UK Limited. - 1468-6996 .- 1878-5514. ; 15:3
-
Tidskriftsartikel (refereegranskat)abstract
- There can be a large variation in the measured diameter of nanoparticles depending on which method is used. In this work, we have strived to accurately determine the mean particle diameter of 3040 nm colloidal silica particles by using six different techniques. A quantitative agreement between the particle size distributions was obtained by scanning electron microscopy (SEM), and electrospray-scanning mobility particle sizer (ES SMPS). However, transmission electron microscopy gave a distribution shifted to smaller sizes. After confirming that the magnification calibration was consistent, this was attributed to sample preparation artifacts. The hydrodynamic diameter, d(h), was determined by dynamic light scattering (DLS) both in batch mode, and hyphenated with sedimentation field flow fractionation. Surprisingly the dh were smaller than the SEM, and ES SMPS diameters. A plausible explanation for the smaller sizes found with DLS is that a permeable gel layer forms on the particle surface. Results from nanoparticle tracking analysis were strongly biased towards larger diameters, most likely because the silica particles provide low refractive index contrast. Calculations confirmed that the sensitivity is, depending on the shape of the laser beam, strongly size dependent for particles with diameters close to the visualization limit.
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| 13. |
- Arvidsson, Rickard, 1984, et al.
(författare)
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Exposure assessments of nanoparticles in aquatic environments – considerations, review and recommendations
- 2013
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Synthetic nanoparticles are new forms of chemical substances. They can be found in several different forms, such as free particles, surface bound and dissolved in liquid. Nanoparticles can also exist as free, individual particles or agglomerate consisting of multiple particles. This report discusses the assessment of possible risks of nanoparticles. Chemical risk is usually considered to consist of two elements: (1) Exposure to the substance, and (2) the substance's toxicity. So far, the risk-related research on nanoparticles has had a strong focus on the particles ' toxic effects. In this report, we would instead focus on how exposure to nanoparticles can be calculated and assessed, with focus on nanoparticles in water. In the report, we provide an initial background and definitions of nanomaterials and nanoparticles, and describe briefly a standard method of risk assessment of chemicals in the environment. Then we go through important considerations that should be made in the exposure assessment of nanoparticles. First we discuss three considerations related to the emissions of nanoparticles, namely the lack of data for annual production of nanoparticles, the importance of applying a substance flow perspective, and lack of data for so-called emission factors for nanoparticles of various products and materials. Furthermore, we discuss considerations for modeling of nanoparticles behavior in water, mainly by listing a number of key processes with large influence. These are agglomeration, sedimentation, and dissolution. Related to that, we discuss how natural organic materials, coatings and aging of particles can affect these processes. We note here three particle properties that are important in order to describe nanoparticles dispersion in water, in a similar way that the octanol-water partition coefficient and half-life is important to describe the fate of organic chemicals in the environment. For nanoparticles these are the particle size (a) and the density (ρ). We also identify a number of more complex parameters affecting particle behavior in the environment, but not only because of the different particle characteristics, but also depending on characteristics related to the environment. These are the collision efficiency (α), point of zero charge (pHpzc), Hamaker constant (A) and a so-called form factor (β) that affect the sedimentation. In addition to the general difficulty to measure or calculate these parameters they also co-vary. Furthermore, we make a review of 11 currently available exposure models for nanoparticles in aquatic environment. We note that the studies differ regarding modeling method, which sources of emissions that are included, the nanoparticles taken into account, estimated concentrations in the environment, and whether the results are presented as mass or particle concentration. Only two studies trying to model the nanoparticle exposure based on particle properties in a manner similar to standard methods for chemical risk assessment. The other modeling studies are instead based on data on flows of specific nanomaterials, and not on generic algorithms. Next, we describe a number of challenges that occur when measuring nanoparticles in the environment. Finally, we provide the following recommendations to ensure good exposure assessment of nanoparticles in the future: 1. Information of flows and stocks of nanoparticles in society need to be collected. 2. Emission factors would need to be developed for each product that makes use of nanoparticles. 3. Emissions should be reported both as mass and particle number until it becomes clearer which one is most relevant. 4. More research is needed in order to determine which particle properties need to be known in order to calculate the concentration of nanoparticles in the environment. 5. At least the particle size and particle size distribution, as well as the specific particle density should be reported. 6. More research is required to improve the experimental measurements of nanoparticles to be able to validate exposure models.
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| 14. |
- Badetti, Elena, et al.
(författare)
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Novel multimethod approach for the determination of the colloidal stability of nanomaterials in complex environmental mixtures using a global stability index: TiO2 as case study
- 2021
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697. ; 801
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Tidskriftsartikel (refereegranskat)abstract
- A systematic study on the colloidal behavior of uncoated and polyvinylpyrrolidone (PVP) coated TiO2 engineered nanomaterials (ENMs) in simulated aqueous media is herein reported, in which conditions representative for natural waters (pH, presence of divalent electrolytes (i.e. Ca2+/Mg2+ and SO42−), of natural organic matter (NOM) and of suspended particulate matter (SPM)) were systematically varied. The colloidal stability of the different dispersions was investigated by means of Dynamic and Electrophoretic Light Scattering (DLS and ELS) and Centrifugal Separation Analysis (CSA), and a global stability index based on these three techniques was developed. The index allows to quantitatively classify the nano-based dispersions according to their colloidal stability affected by the different parameters studied. This multimethod approach clearly identifies inorganic SPM followed by divalent electrolytes as the main natural components destabilizing TiO2 ENMs upon entering in simulated natural waters, while it highlights a moderate stabilization induced by NOM, depending mainly on pH. Moreover, the PVP coating was found to attenuate the influence of these parameters on the colloidal stability. The obtained results show how the global stability index developed is influenced by the complexity of the system, suggesting the importance of combining the information gathered from all the techniques employed to better elucidate the fate and behavior of ENMs in natural surface waters.
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| 15. |
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| 16. |
- Farkas, Julia, et al.
(författare)
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Characterization of the effluent from a nanosilver producing washing machine
- 2011
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Ingår i: Environment International. - : Elsevier BV. - 0160-4120 .- 1873-6750. ; 37:6, s. 1057-1062
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Tidskriftsartikel (refereegranskat)abstract
- The increasing number of nanomaterial based consumer products raises concerns about their possible impact on the environment. This study provides an assessment of the effluent from a commercially available silver nanowashing machine. The washing machine released silver in its effluent at an average concentration of 11 mu g L(-1), as determined by inductive coupled mass spectrometry (ICP-MS). The presence of silver nanoparticles (AgNPs) was confirmed by single particle ICP-MS as well as ion selective electrode measurements and filtration techniques. Size measurements showed particles to be in the defined nanosize range, with an average size of 10 nm measured with transmission electron microscopy (TEM) and 60-100 nm determined with nanoparticle tracking analysis (NTA). The effluent was shown to have negative effects on a natural bacterial community as its abundance was clearly reduced when exposed to the nanowash water. If washing machines capable of producing AgNPs become a common feature of households in the future, wastewater will contain significant loadings of AgNPs which might be released into the environment.
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| 17. |
- Farkas, Julia, et al.
(författare)
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Effects of silver and gold nanoparticles on rainbow trout (Oncorhynchus mykiss) hepatocytes.
- 2010
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Ingår i: Aquatic toxicology (Amsterdam, Netherlands). - : Elsevier BV. - 1879-1514 .- 0166-445X. ; 96:1, s. 44-52
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Tidskriftsartikel (refereegranskat)abstract
- The use of nanomaterials is rapidly increasing, while little is known about their possible ecotoxicological effects. This work investigates the toxic effects of silver (Ag) and gold (Au) nanoparticles on rainbow trout hepatocytes. In addition to toxicity assessment the particles were characterized by transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA). Hepatocyte primary cultures were exposed to Au and Ag nanoparticles, with and without dissolved organic carbon (DOC), as well as HAuCl(4) and AgNO(3) as ionic solutions at concentrations up to 17.4mg/L and 19mg/L, respectively. Ag and Au particles were within the small nanometer size range when dispersed in pure water. In media with higher ionic strength and DOC, particles tended to agglomerate. Cytotoxicity assessments showed that Ag nanoparticles caused a significant reduction in membrane integrity and cellular metabolic activity in a concentration-dependent manner. Au nanoparticles caused a threefold elevation of ROS levels, but no cytotoxicity occurred at concentrations tested. The addition of DOC did not alter the particles potency of cytotoxicity or ROS induction capacity. The current study shows that Ag and Au nanoparticles have adverse effects on rainbow trout hepatocytes at low mg/L concentrations.
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| 18. |
- Farkas, Julia, et al.
(författare)
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Uptake and effects of manufactured silver nanoparticles in rainbow trout (Oncorhynchus mykiss) gill cells.
- 2011
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Ingår i: Aquatic toxicology (Amsterdam, Netherlands). - : Elsevier BV. - 1879-1514 .- 0166-445X. ; 101:1, s. 117-25
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Tidskriftsartikel (refereegranskat)abstract
- Nanoparticles are already widely used in technology, medicine and consumer products, but there are limited data on their effects on the aquatic environment. In this study the uptake and effect of citrate (AgNP(CIT)) and polyvinylpyrrolidone (AgNP(PVP)) coated manufactured silver nanoparticles, as well as AgNO(3) (Ag(+)) were tested using primary gill cells of rainbow trout (Oncorhynchus mykiss). Prior to use, the nanoparticles were characterized for size, surface charge and aggregation behavior. Gill cells were cultured either as monolayers on solid support, or as multilayers on a permeable support cell culturing system, enabling transport studies. The uptake of silver nanoparticles and Ag(+) after exposure to 10 mg L(-1) was determined with microscopical methods and inductively coupled plasma mass spectrometry (ICP-MS). Cytotoxicity, in terms of membrane integrity, as well as oxidative stress (depletion of reduced glutathione) was tested at silver concentrations ranging from 0.1 mg L(-1) to 10 mg L(-1). Results show that AgNP(CIT) nanoparticles are readily taken up into gill cell monolayers while uptake was less for AgNP(PVP). In contrast, it appears that the slightly smaller AgNP(PVP) were transported through cultured multilayers to a higher extent, with transport rates generally being in the ng cm(-2) range for 48 h exposures. Transport rates for all exposures were dependent on the epithelial tightness. Moderate cytotoxic effects were seen for all silver treatments. Levels of reduced glutathione were elevated in contrast to control groups, pointing on a possible overcompensation reaction. Taken together silver nanoparticles were taken up into cells and did cause silver transport over cultured epithelial layers with uptake and transport rates being different for the two nanoparticle species. All silver treatments had measurable effects on cell viability.
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| 19. |
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| 20. |
- Gallego-Urrea, Julian A., 1977, et al.
(författare)
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Coagulation and sedimentation of gold nanoparticles and illite in model natural waters: Influence of initial particle concentration
- 2016
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Ingår i: NanoImpact. - : Elsevier BV. - 2452-0748. ; 3-4, s. 67-74
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Tidskriftsartikel (refereegranskat)abstract
- Gold nanoparticles (AuNP) possess unique characteristics that render them adequate for applications and also to be used as a model NP to evaluate the fate and behavior at low NP concentrations due to the ease of detection by modern analytical techniques. Moreover, AuNP may result in some negative effects in the environment and there is a necessity to predict their aquatic environmental concentrations by parameterizing the underlying transport and transformation processes. This study investigated the coagulation and sedimentation of 30 nm citrate-coated AuNP under enviro-mimicking conditions, i.e. model natural freshwaters (MNW) covering the range of European water chemistries relevant for colloids and NP (major ions, pH and dissolved organic matter) and artificial seawater (ASW). Firstly, the coagulation rates of AuNP at mg/L concentrations were evaluated using time-resolved dynamic light scattering which showed a decreased rate upon addition of Suwannee river natural organic matter (SRNOM) at low ionic strength (IS) but remained relatively high at high IS. Contrastingly, AuNP approaching environmental realistic concentrations (80 μg/L) in quiescent microcosms showed slow decline rates in all MNW and ASW regardless of the presence of SRNOM, as measured by nanoparticle tracking analysis and elemental Au spectrometry. When illite was added as model natural colloid the rates of decline of AuNP remained low as well. This is owing to limited collisions at low particle number concentrations. The results show that besides IS, pH, NOM concentration and type and the intrinsic surface charge of the particles, the particle number concentration and size distribution of both AuNP and natural colloids determine the extent of the large-scale fate of NP in aquatic environments.
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| 21. |
- Gallego-Urrea, Julian A., 1977, et al.
(författare)
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Determination of pH in estuarine and brackish waters: Pitzer parameters for Tris buffers and dissociation constants for m-cresol purple at 298.15K
- 2017
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Ingår i: Marine Chemistry. - : Elsevier BV. - 0304-4203. ; 195, s. 84-89
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Tidskriftsartikel (refereegranskat)abstract
- © 2017 Elsevier B.V. Measurements of pH in seawater are important to determine the natural and anthropogenic trends in the oceans. Spectrophotometry or glass electrode potentiometry measurements of pH require calibration with help of buffers. One common buffer solution is the Tris/Tris·H + couple, which should be well characterised both experimentally and theoretically for optimum accuracy. Chemical speciation modelling in the complex seawater medium is best addressed with an ion interaction approach, with Pitzer equations being the most widely used. The published Pitzer coefficients for Tris and Tris·H + in artificial seawater are based on isopiestic measurements, which necessarily give strong weight to the third virial coefficient C for the key interaction between Tris·H + and chloride. However, in low salinity waters it is the second virial coefficient B that is of greater importance. We have used Harned cell measurements of Tris solutions at ionic strengths up to 1molkg -1 to reassess the relevant Pitzer parameters, and have found improved agreement with experimental measurements in artificial seawater. We suggest that additional measurements should be undertaken to address the remaining differences between model calculations and experimental data in artificial seawater. We have used the revised Pitzer parameters to reassess the acid-base constant of the indicator m-cresol purple in low salinity waters.
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| 22. |
- Gallego-Urrea, Julian A., 1977, et al.
(författare)
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Measurements of nanoparticle number concentrations and size distributions in contrasting aquatic environments using nanoparticle tracking analysis
- 2010
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Ingår i: Environmental Chemistry. - 1449-8979. ; 7, s. 67-81
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Tidskriftsartikel (refereegranskat)abstract
- A feasibility study of nanoparticle tracking analysis (NTA) for aquatic environmental samples is presented here. The method has certain virtues such as minimum perturbation of the samples, high sensitivity in terms of particle concentration, and provision of number-based size distributions for aquatic samples. NTA gave linear calibration curves in terms of number concentration and accurately reproduced size measurements of certified reference material nanoparticles. However, the accuracy of the size distributions obtained with this method exhibited a high dependence on set-up parameters and the concentrations were shown to be strongly correlated with the refractive index of the material under examination. Different detection cameras and different data acquisition modeswere compared and evaluated. Also, the effect of filtration of the samples was assessed. The size distributions for the contrasting environmental samples were fairly reasonable compared with other studies but an underestimation of small sizes was observed, which can be explained by a materialdependent lower detection limit in terms of size. The number concentrations obtained for the natural nanoparticles ranged from 0.5 to 20×108 particles mL−1 and correlated well with conventional turbidity measurements.
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| 23. |
- Gallego-Urrea, Julian A., 1977, et al.
(författare)
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Multimethod 3D characterization of natural plate-like nanoparticles: shape effects on equivalent size measurements
- 2014
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Ingår i: Journal of nanoparticle research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 16:5
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Tidskriftsartikel (refereegranskat)abstract
- The fundamental properties and processes that govern nanoparticle behavior in colloidal dispersions are critical to predict their performance in applications and also their environmental and health implications. Illite is a platy clay mineral that is present in large amounts in aquatic environments and can be used as a model natural particle for environmental risk assessment. However, the high-aspect ratio of illite makes conventional analysis, usually assuming a spherical size, insufficient for the assessment of shape-dependent properties. In the current paper, a multimethod characterization of a suspension of illite particles was done using atomic force microscopy, scanning electron microscopy, dynamic light scattering (DLS), nanoparticle tracking analysis, differential centrifugal sedimentation, and centrifugal- field flow fractionation coupled to multiangle light scattering and DLS. The relation between the different measurands was investigated, and the effect of the shape on the equivalent particle size was reported. While some of the used techniques are capable of assessing the aspect ratio of illite, the results confirm the need for multiple techniques and analysis of different types of measurands especially for high-aspect-ratio particles.
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| 24. |
- Gallego-Urrea, Julian A., 1977
(författare)
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On the exposure assessment of engineered nanoparticles in aquatic environments
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The socio-economic benefits anticipated with the use and production of nanomaterial and nanoparticles in consumer products are linked to the fulfillment of the requirement for sustainability during the whole material life cycle. Engineered nanoparticles (ENP) can be of environmental concern, both due to the possible hazardous effects but also due to the differences in properties compared to regular chemicals, e.g. elevated surface area per mass of nanoparticle, the possibility for enhanced mobility and trespassing biological membranes and other emerging novel properties at the nanoscale. There is a scientific consensus that nanoparticles, nanomaterials and their transformation products have a high probability to be released in the environment. ENP in the aquatic environment present a very dynamic behavior that has to be understood in order to perform a physicochemical-based risk assessment that elucidates their transformation and transport leading to the possibility to predict environmental concentrations and exposure. Therefore, there is a need for adequate theoretical and experimental platforms that can be used for supporting the adequate assessment of fate processes of ENP in the environment. The main results achieved in the thesis were reflected in: 1) identification of theoretical platforms that can provide solutions for the evaluation of fate processes of ENP in aquatic environments 2) improvement in the application of a novel particle tracking method for characterizing natural nanoparticles and ENP in different matrices; 3) identification of the effects of well-characterized NOM and counterion valence on the aggregation rates of TiO2 nanoparticles 4) developing a geographically distributed water classification for Europe based on river water chemistry, 5) use the geographical water classification to evaluate the aggregation and sedimentation of Au NP in in-situ quiescent-water microcosms. The physicochemical characteristics of the receiving water were found to be very influential on the fate of the ENP tested. The ionic concentration, presence of divalent counter ions (specifically calcium), the type of NOM and mass-ratio between NOM and the particles are among the most important parameters. NP coating, surface charge, material properties and shape will also play very important roles. NP number concentrations determine the degree of transport and transformation due to the different dynamic processes in the environment.
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| 25. |
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| 26. |
- Gonçalves, Sandra F., et al.
(författare)
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Effects of silver nanoparticles to the freshwater snail Physa acuta: The role of test media and snails' life cycle stage
- 2017
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Ingår i: Environmental Toxicology and Chemistry. - : Wiley. - 0730-7268 .- 1552-8618. ; 36:1, s. 243-253
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Tidskriftsartikel (refereegranskat)abstract
- Silver nanoparticles (AgNP) are highly used worldwide, which will most likely lead to their release to the environment and subsequently increase environmental concentrations. Therefore studying AgNPs' deleterious effects to organisms is crucial to understand their environmental impacts. The freshwater snail Physa acuta was chosen to evaluate the potential deleterious effects of AgNP and counterpart AgNO3, through water only exposures. AgNPs' toxicity is greatly influenced by medium composition. Thus, two test media were tested: Artificial Pond Water (APW) and modified APW (modified by removing calcium chloride from medium). Acute tests (96h) were performed with juvenile and adult snails, in both media, to assess lethality, and egg mass chronic tests, with APW medium only, to assess embryo viability and mortality, carried out until reaching 90% hatching success in the control. Acute toxicity increased with decreasing shell length for both silver forms (ion and nanoparticle), i.e. juveniles where more sensitive than adults. Different test media led to dissimilar LC50 values, with chloride playing an important role in toxicity, most probably by complexation with silver ions and thus reducing silver's bioavailability, uptake and toxicity. Chronic tests showed that hatching success was more sensitive to silver in the ionic form than in the particulate form. Different forms of silver, exposure media and life cycle stages led to different patterns of toxicity, highlighting an impairment in the snails' life cycle.
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| 27. |
- Gondikas, Andreas P., 1981, et al.
(författare)
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Nanomaterial Fate in Seawater: A Rapid Sink or Intermittent Stabilization?
- 2020
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Ingår i: Frontiers in Environmental Science. - : Frontiers Media SA. - 2296-665X. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Coastal seas and oceans receive engineered nanoparticles that are released from nano-enabled consumer and industrial products and incidental nanoparticles that are formed as byproducts of combustion and friction. The marine environment is often perceived as a rapid sink for particles, because of the high salinity promoting the attachment between particles producing heavy agglomerates that sediment on the seafloor. In this work the effect of seasonal production of extracellular polymeric substances (EPS) on particle stability is tested using seawater collected from the Gullmarn fjord in the winter, spring, and summer. A novel approach is used that is based on light scattering of the bulk particle population for tracking agglomerates and of single particles for tracking particles smaller than approximately 300 nm. Results show that organic particles formed from EPS during algal blooms are capable of stabilizing nanoparticles in marine waters for at least 48 h. In contrast, particles agglomerate rapidly in the same seawater that has previously been filtered through 0.02 mu m pore size membranes. Furthermore, particles with fibrillar shape have been detected using atomic force microscopy, supporting the argument that organic particles from EPS are responsible for the stabilization effect. These results suggest that seasonal biological activity can act as an intermittent stabilization factor for nanoparticles in marine waters.
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| 28. |
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| 29. |
- Hammes, Julia, et al.
(författare)
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Geographically distributed classification of surface water chemical parameters influencing fate and behavior of nanoparticles and colloid facilitated contaminant transport.
- 2013
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Ingår i: Water Research. - : Elsevier BV. - 0043-1354. ; 47:14, s. 5350-5361
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Tidskriftsartikel (refereegranskat)abstract
- The current production and use of nanomaterials in consumer products have increased the concern about the possibility that these enter the rivers during their entire life cycle. Further, many aquatic contaminants undergo partitioning to the ubiquitous aquatic colloids. Here is presented the development of a set of European water types for environmental risk assessment of chemicals transported as nanovectors as is the case of environmental fate of manufactured nanoparticles and colloid-bound contaminants. A compilation of river quality geochemical data with information about multi-element composition for near 800 rivers in Europe was used to perform a principal component analysis (PCA) and define 6 contrasting water classes. With the aid of geographical information system algorithms, it was possible to analyse how the different sampling locations were predominantly represented within each European water framework directive drainage basin. These water classes and their associated Debye–Hückel parameter are determining factors to evaluate the large scale fate and behaviour of nanomaterials and other colloid-transported pollutants in the European aquatic environment.
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| 30. |
- Hopwood, Mark J., et al.
(författare)
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Experiment design and bacterial abundance control extracellular H2O2 concentrations during four series of mesocosm experiments
- 2020
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 17, s. 1309-1326
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Tidskriftsartikel (refereegranskat)abstract
- © Author(s) 2020. The extracellular concentration of H2O2 in surface aquatic environments is controlled by a balance between photochemical production and the microbial synthesis of catalase and peroxidase enzymes to remove H2O2 from solution. In any kind of incubation experiment, the formation rates and equilibrium concentrations of reactive oxygen species (ROSs) such as H2O2 may be sensitive to both the experiment design, particularly to the regulation of incident light, and the abundance of different microbial groups, as both cellular H2O2 production and catalase-peroxidase enzyme production rates differ between species. Whilst there are extensive measurements of photochemical H2O2 formation rates and the distribution of H2O2 in the marine environment, it is poorly constrained how different microbial groups affect extracellular H2O2 concentrations, how comparable extracellular H2O2 concentrations within large-scale incubation experiments are to those observed in the surface-mixed layer, and to what extent a mismatch with environmentally relevant concentrations of ROS in incubations could influence biological processes differently to what would be observed in nature. Here we show that both experiment design and bacterial abundance consistently exert control on extracellular H2O2 concentrations across a range of incubation experiments in diverse marine environments. During four large-scale (> 1000 L) mesocosm experiments (in Gran Canaria, the Mediterranean, Patagonia and Svalbard) most experimental factors appeared to exert only minor, or no, direct effect on H2O2 concentrations. For example, in three of four experiments where pH was manipulated to 0.4-0.5 below ambient pH, no significant change was evident in extracellular H2O2 concentrations relative to controls. An influence was sometimes inferred from zooplankton density, but not consistently between different incubation experiments, and no change in H2O2 was evident in controlled experiments using different densities of the copepod Calanus finmarchicus grazing on the diatom Skeletonema costatum (< 1 % change in [H2O2] comparing copepod densities from 1 to 10 L-1). Instead, the changes in H2O2 concentration contrasting high-and low-zooplankton incubations appeared to arise from the resulting changes in bacterial activity. The correlation between bacterial abundance and extracellular H2O2 was stronger in some incubations than others (R2 range 0.09 to 0.55), yet high bacterial densities were consistently associated with low H2O2. Nonetheless, the main control on H2O2 concentrations during incubation experiments relative to those in ambient, unenclosed waters was the regulation of incident light. In an open (lidless) mesocosm experiment in Gran Canaria, H2O2 was persistently elevated (2-6-fold) above ambient concentrations; whereas using closed high-density polyethylene mesocosms in Crete, Svalbard and Patagonia H2O2 within incubations was always reduced (median 10 %-90 %) relative to ambient waters.
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| 31. |
- Hopwood, Mark J., et al.
(författare)
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Fe(II) stability in coastal seawater during experiments in Patagonia, Svalbard, and Gran Canaria
- 2020
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 17, s. 1327-1342
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Tidskriftsartikel (refereegranskat)abstract
- © Author(s) 2020. The speciation of dissolved iron (DFe) in the ocean is widely assumed to consist almost exclusively of Fe(III)-ligand complexes. Yet in most aqueous environments a poorly defined fraction of DFe also exists as Fe(II), the speciation of which is uncertain. Here we deploy flow injection analysis to measure in situ Fe(II) concentrations during a series of mesocosm/microcosm/multistressor experiments in coastal environments in addition to the decay rate of this Fe(II) when moved into the dark. During five mesocosm/microcosm/multistressor experiments in Svalbard and Patagonia, where dissolved (0.2 μ m) Fe and Fe(II) were quantified simultaneously, Fe(II) constituted 24 %-65 % of DFe, suggesting that Fe(II) was a large fraction of the DFe pool. When this Fe(II) was allowed to decay in the dark, the vast majority of measured oxidation rate constants were less than calculated constants derived from ambient temperature, salinity, pH, and dissolved O2. The oxidation rates of Fe(II) spikes added to Atlantic seawater more closely matched calculated rate constants. The difference between observed and theoretical decay rates in Svalbard and Patagonia was most pronounced at Fe(II) concentrations < 2 nM, suggesting that the effect may have arisen from organic Fe(II) ligands. This apparent enhancement of Fe(II) stability under post-bloom conditions and the existence of such a high fraction of DFe as Fe(II) challenge the assumption that DFe speciation in coastal seawater is dominated by ligand boundFe(III) species.
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| 32. |
- Nielsen, Maria, et al.
(författare)
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Nanomaterials in the European chemicals legislation-methodological challenges for registration and environmental safety assessment
- 2021
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Ingår i: Environmental Science: Nano. - : Royal Society of Chemistry. - 2051-8153 .- 2051-8161. ; 8:3, s. 731-747
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Tidskriftsartikel (refereegranskat)abstract
- In the European Union the Annexes of its chemical legislation (REACH) were revised and now clarify the technical data requirements for nanomaterials (NMs). These new provisions, effective from January 1, 2020, introduce requirements for manufacturers, importers and downstream users regarding registration and safety assessment of NMs. This study aims to assess the availability and suitability of methods needed to comply with the new regulatory provisions on NMs for physico-chemical characterisation and environmental fate and effects. The scientific literature and relevant test guideline frameworks were reviewed to identify applicable methods. These were subsequently evaluated and categorised as either: 'internationally accepted test guideline or standard (TGS)', 'internationally accepted test guideline or standard under development (TGSUD)', 'established as standard methods in scientific literature (SCI)', 'other methods and/or more research needed (O)' or 'no method (N)'. We find that 80% of the information requirements and a bit more than 40% of the waiving criteria in the new REACH Annexes are supported by methods that are available as TGS, TGSUD or SCI. Most of the relevant methods in the scientific literature are included in recent OECD guidance documents or ECHA guidance. We recommend that a targeted effort is made to develop protocols and guidelines for methods to determine NM adsorption/desorption, degradation, exposure scenarios and ability to cross biological membranes. Here methods to fulfil the information requirements and waiving criteria are currently lacking. Furthermore, we recommend that increasing attention is directed towards regulatory reliability and relevance of the information that is submitted by the registrants.
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| 33. |
- Rama, Prasad, et al.
(författare)
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Interfacial interactions of humic acids with polystyrene nano-plastics in aqueous/ionic environments: a molecular dynamics exploration
- 2023
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Ingår i: Environmental Science-Nano. - : Royal Society of Chemistry (RSC). - 2051-8153 .- 2051-8161. ; 10:5
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Tidskriftsartikel (refereegranskat)abstract
- Plastics pose a serious threat to both marine and freshwater life after being discarded and broken down into smaller particles such as micro and nano-plastic particles. The nano-sized plastic particles are small enough in size and similar to surfaces of biological molecules, thereby potentially altering the intra-cellular interactions and their biological fate. In order to increase our understanding of the interactions among the molecules of natural organic matter and carboxylate functionalized polystyrene nano-plastics, we have performed a modelling study of the aquatic environment at different pH conditions using molecular dynamics (MD) simulations at an atomistic scale. Humic acids (HAs) are the most common constituents of natural organic matter, usually found in soil, water, and its sediments. As a proxy for humic acids, we have used Temple-Northeastern-Birmingham (TNB), an equivalent molecule to HA in its composition. We show that TNB molecules exhibit strong interactions with polystyrene (PS) nano-plastic particles at pH-4 but weak interaction at pH-7, whereas moderate interaction at pH-9 both in fresh and saltwater. The interaction between carboxylated polystyrene particles and TNB molecules is found to be counter-ion mediated and is enhanced in the presence of saltwater, i.e., at 0.5 M NaCl electrolyte. An enhanced condensation of Na+ counter-ions onto the surface of nano-plastics brings more water molecules to its interface, hence, enriching the hydrophilicity of nano-plastics. An ordered network structure of water molecules has also been observed at the interface of the PS-slab with an increase in pH of the aquatic environment, leading to a preferential alignment of water molecules, resulting in a strong hydration layer. This strong hydration layer also keeps the TNB molecules away from the vicinity of the PS-slab interface. The surface potential trends obtained from the MD simulations are in agreement with the measured zeta potential values showing that the surface charge density of PS nano-plastics increases with an increase in the pH of aquatic solutions. Hence, our simulations provide molecular-level insights into the phenomenon associated with the adsorption/accumulation of molecules of natural organic matter towards the nano-plastics and are helpful in understanding the formation of eco-corona on plastic nanoparticles.
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| 34. |
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| 35. |
- Stábile, Franca, et al.
(författare)
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Fate and biological uptake of polystyrene nanoparticles in freshwater wetland ecosystems
- 2024
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Ingår i: ENVIRONMENTAL SCIENCE-NANO. - 2051-8153 .- 2051-8161.
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Tidskriftsartikel (refereegranskat)abstract
- Little is known about the fate and uptake of nanoplastics (NPs) in natural ecosystems, mainly due to analytical limitations in measuring NPs in complex environmental matrices. Our aim was to quantitatively assess the transport, fate and biological uptake of NPs in freshwater ecosystems by using replicated wetland mesocosms and gold-doped polystyrene nanoparticles. We showed that 97% of the NPs were retained in the wetlands, with most of them found in the sediment of the mesocosm's lake compartment. A small fraction (3%) of the NPs left the system through the outlet. After 10 weeks of exposure, both filter feeders (Daphnia magna) and detritivores (Asellus aquaticus) had taken up NPs, with D. magna showing a 5 times higher uptake than A. aquaticus. Moreover, NPs were detected in macrophyte roots and their leaves, with significantly higher values in the roots. NP distribution was negatively related with distance from the point of addition, a relation observed both for sediments and macrophytes. Both with respect to the experimental set-up and NP concentrations, our study provides novel insights to the understanding of the fate and uptake of NPs, a contaminant of emerging concern, in natural scenarios. In a broader context, our study also provides crucial knowledge for risk assessment and support for decision-makers and ongoing legislative work regarding nanoplastics. Wetland mesocosms retained nanoplastics. Nanoplastics where taken up by freshwater invertebrates and macrophytes and mainly ended up in the sediments of the water compartment.
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| 36. |
- Turner, David R., 1951, et al.
(författare)
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The potential future contribution of shipping to acidification of the Baltic Sea
- 2018
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 47:3, s. 368-378
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Tidskriftsartikel (refereegranskat)abstract
- © 2017 The Author(s) International regulation of the emission of acidic sulphur and nitrogen oxides from commercial shipping has focused on the risks to human health, with little attention paid to the consequences for the marine environment. The introduction of stricter regulations in northern Europe has led to substantial investment in scrubbers that absorb the sulphur oxides in a counterflow of seawater. This paper examines the consequences of smokestack and scrubber release of acidic oxides in the Baltic Sea according to a range of scenarios for the coming decades. While shipping is projected to become a major source of strong acid deposition to the Baltic Sea by 2050, the long-term effect on the pH and alkalinity is projected to be significantly smaller than estimated from previous scoping studies. A significant contribution to this difference is the efficient export of surface water acidification to the North Sea on a timescale of 15–20 years.
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