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Sökning: WFRF:(Cornelis Geert)

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1.
  • Baalousha, M., et al. (författare)
  • Modeling nanomaterial fate and uptake in the environment: current knowledge and future trends
  • 2016
  • Ingår i: Environmental Science-Nano. - : Royal Society of Chemistry (RSC). - 2051-8153 .- 2051-8161. ; 3:2, s. 323-345
  • Tidskriftsartikel (refereegranskat)abstract
    • Modeling the environmental fate of nanomaterials (NMs) and their uptake by cells and organisms in the environment is essential to underpin experimental research, develop overarching theories, improve our fundamental understanding of NM exposure and hazard, and thus enable risk assessment of NMs. Here, we critically review the state-of-the-art of the available models that can be applied/adapted to quantify/predict NM fate and uptake in aquatic and terrestrial systems and make recommendations regarding future directions for model development. Fate models have evolved from substance flow analysis models that lack nano-specific processes to more advanced mechanistic models that (at least partially) take nano-specific (typically non-equilibrium, dynamic) processes into account, with a focus on key fate processes such as agglomeration, sedimentation and dissolution. Similarly, NM uptake by organisms is driven by dynamic processes rather than by equilibrium partitioning. Hence, biokinetic models are more suited to model NM uptake, compared with the simple bio-accumulation factors used for organic compounds. Additionally, biokinetic models take speciation processes (e.g. particulate versus ionic uptake) into account, although identifying essential environment-specific processes to include in models remains a challenge. The models developed so far require parameterization, calibration and validation with available data, e.g. field data (if available), or experimental data (e.g. aquatic and terrestrial mesocosms), rather than extension to more complex and sophisticated models that include all possible transformation processes. Collaborative efforts between experimentalists and modelers to generate appropriate ground-truth data would advance the field most rapidly.
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2.
  • Cornelis, Geert, 1978, et al. (författare)
  • A signal deconvolution method to discriminate smaller nanoparticles in single particle ICP-MS
  • 2014
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477. ; 29:1, s. 134-144
  • Tidskriftsartikel (refereegranskat)abstract
    • Single particle ICP-MS (spICP-MS) analysis of inorganic nanoparticles (NPs) cannot accurately distinguish dissolved ion signals and signals from relatively small NPs, although these particles are often more reactive than their larger counterparts. A signal deconvolution method was developed for spICP-MS analysis using gold (Au) NPs of nominally 10, 15 or 30 nm diameter. The signal distributions of dissolved Au standards were parameterised as a function of concentration using a mixed Polyagaussian probability mass function. Dissolved curves were fitted using this parameterisation to the low-intensity signals of samples containing NPs to subtract and deconvolute the dissolved signals from the particle signals. The dissolved signals were quantified in this process. The accuracy of the deconvolution method was confirmed for all NP suspensions studied when comparing the size and number concentration obtained with the deconvolution method with values based on transmission electron microscopy. This method thus allows analysis of NP suspensions with spICP-MS where it was hitherto not possible. The applicability domain lies predominantly with relatively small NPs and/or when a relatively high concentration of dissolved ions of the element of interest is present, where overlapping between dissolved and particulate signals occurs.
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3.
  • Cornelis, Geert, 1978, et al. (författare)
  • Antimony leaching from MSWI bottom ash: Modelling of the effect of pH and carbonation
  • 2012
  • Ingår i: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 32:2, s. 278-286
  • Tidskriftsartikel (refereegranskat)abstract
    • Development of treatment methods to reduce Sb leaching from municipal solid waste incinerator (MSWI) bottom ash, such as accelerated carbonation, is being complicated by insufficient understanding of Sb geochemistry. The leaching of antimonate (Sb(V)) and antimonite (Sb(III)) in MSWI bottom was studied as a function of pH and degree of carbonation. While total (Sb(V)+Sb(III)) leaching was lowest (1.2mgkg-1) at the natural pH (i.e. 10.6) of uncarbonated bottom ash, HPLC-ICP-MS analysis showed that acidification and carbonation increased Sb(V) leaching, but decreased Sb(III) leaching, probably because Sb(III)(OH)4- became less stable. PHREEQC geochemical modelling suggested that Sb(V) concentrations approached equilibrium with the romeites, i.e. calcium antimonates, Ca1.13Sb2(OH)0.26·0.74H2O at pH=10.6 and Ca[Sb(OH)6]2at pH=8. It is hypothesised that not interaction with ettringite but dissolution of romeite controls antimonate leaching in the pH range 8-11 in MSWI bottom ash, because while Ca is preferentially leached from romeite, the mineral structures containing more Ca at higher pH are less soluble. A model was proposed where acidification and carbonation both lead to lower Ca2+and/or hydroxyl concentration, which removes Ca2+and hydroxyls from the romeite structure and leads to comparably higher Sb(V) concentration in equilibrium with romeite. Sb solubility depends on pH and Ca2+availability in this model, which has implications for bottom ash valorisation and risk assessment. © 2011 Elsevier Ltd.
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4.
  • Cornelis, Geert (författare)
  • Bioturbation of Ag2S-NPs in soil columns by earthworms
  • 2019
  • Ingår i: Environmental Pollution. - : Elsevier BV. - 0269-7491 .- 1873-6424. ; 252, s. 155-162
  • Tidskriftsartikel (refereegranskat)abstract
    • Sewage sludge contains Ag2S-NPs causing NP exposure of soil fauna when sludge is applied as soil amendment. Earthworm bioturbation is an important process affecting many soil functions. Bioturbation may be affected by the presence of Ag2S-NPs, but the earthworm activity itself may also influence the displacement of these NPs that otherwise show little transport in the soil. The aim of this study was to determine effects of Ag2S-NPs on earthworm bioturbation and effect of this bioturbation on the vertical distribution of Ag2S-NPs. Columns (12 cm) of a sandy loamy soil with and without Lumbricus rubellus were prepared with and without 10 mg Ag kg(-1), applied as Ag2S-NPs in the top 2 cm of the soil, while artificial rainwater was applied at similar to 1.2 mm day(-1). The soil columns were sampled at three depths weekly for 28 days and leachate collected from the bottom. Total Ag measurements showed more displacement of Ag to deeper soil layers in the columns with earthworms. The application of rain only did not significantly affect Ag transport in the soil. No Ag was detected in column leachates. X-ray tomography showed that changes in macro porosity and pore size distribution as a result of bioturbation were not different between columns with and without Ag2S-NPs. Earthworm activity was therefore not affected by Ag2S-NPs at the used exposure concentration. Ag concentrations along the columns and the earthworm density allowed the calculation of the bioturbation rate. The effect on the Ag transport in the soil shows that earthworm burrowing activity is a relevant process that must be taken into account when studying the fate of nanoparticles in soils. (C) 2019 Elsevier Ltd. All rights reserved.
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5.
  • Cornelis, Geert, et al. (författare)
  • Challenges and current approaches toward environmental monitoring of nanomaterials
  • 2021
  • Ingår i: Monitoring Environmental Contaminants : A volume in Environmental Contaminants. - 9780444643360 ; , s. 73-108
  • Bokkapitel (refereegranskat)abstract
    • Engineered nanomaterials (ENMs), i.e., man-made particles having at least one dimension smaller than 100nm, have found their way into the environment. Parallel to the efforts to elucidate the possible harmful effects of ENMs, techniques have been developed to monitor environmental ENM concentrations. This chapter discusses the techniques that can currently distinguish ENMs from naturally occurring particles at realistic concentration detection limits without a tedious sample pretreatment procedure. For inorganic ENMs, the most promising approach is based on single particle ICP-MS, and this technique has been developed in recent years to measure solid samples in addition to aquatic samples and distinguish the many different forms of occurrence of ENMs in realistic samples from naturally occurring particles. The detection capabilities for C-based particles are lagging and will likely be the focus of analytical developments in the coming years.
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6.
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7.
  • Cornelis, Geert (författare)
  • Chromium Hazard and Risk Assessment: New Insights from a Detailed Speciation Study in a Standard Test Medium
  • 2018
  • Ingår i: Environmental Toxicology and Chemistry. - : Wiley. - 0730-7268 .- 1552-8618. ; 37, s. 983-992
  • Tidskriftsartikel (refereegranskat)abstract
    • Despite the consensus about the importance of chemical speciation in controlling the bioavailability and ecotoxicity of trace elements, detailed speciation studies during laboratory ecotoxicity testing remain scarce, contributing to uncertainty when extrapolating laboratory findings to real field situations in risk assessment. We characterized the speciation and ecotoxicological effects of chromium (Cr-III and Cr-VI) in the International Organization for Standardization (ISO) medium for algal ecotoxicity testing. Total and dissolved (< 0.22 mu m) Cr concentrations showed little variability in media spiked with Cr-VI, whereas dissolved Cr concentration decreased by as much as 80% over a 72-h time period in medium amended with Cr-III. Analyses by ion chromatography inductively coupled plasma mass spectrometry (IC-ICP-MS) highlighted the absence of redox interconversion between Cr-III or Cr-VI both in the presence and absence of algal cells (Raphidocelis subcapitata). Furthermore, the concentration of ionic Cr-III dropped below detection limits in less than 2 h with the corresponding formation of carbonate complexes and Cr hydroxides. Precipitation of Cr-III in the form of colloidal particles of variable diameters was confirmed by nanoparticle (NP) tracking analysis, single particle ICP-MS, and single particle counting. In terms of time-weighted dissolved (< 0.22 mu m) Cr concentration, Cr-III was 4 to 10 times more toxic than Cr-VI. However, Cr-III ecotoxicity could arise from interactions between free ionic Cr-III and algae at the beginning of the test, from the presence of Cr-bearing NPs, or from a combination of the 2. Future ecotoxicological studies must pay more attention to Cr speciation to reliably compare the ecotoxicity of Cr-III and Cr-VI. (C) 2017 SETAC
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8.
  • Cornelis, Geert, et al. (författare)
  • Drift correction of the dissolved signal in single particle ICPMS
  • 2016
  • Ingår i: Analytical and Bioanalytical Chemistry. - : Springer Science and Business Media LLC. - 1618-2642 .- 1618-2650. ; 408:19, s. 5075-5087
  • Tidskriftsartikel (refereegranskat)abstract
    • A method is presented where drift, the random fluctuation of the signal intensity, is compensated for based on the estimation of the drift function by a moving average. It was shown using single particle ICPMS (spICPMS) measurements of 10 and 60 nm Au NPs that drift reduces accuracy of spICPMS analysis at the calibration stage and during calculations of the particle size distribution (PSD), but that the present method can again correct the average signal intensity as well as the signal distribution of particle-containing samples skewed by drift. Moreover, deconvolution, a method that models signal distributions of dissolved signals, fails in some cases when using standards and samples affected by drift, but the present method was shown to improve accuracy again. Relatively high particle signals have to be removed prior to drift correction in this procedure, which was done using a 3 x sigma method, and the signals are treated separately and added again. The method can also correct for flicker noise that increases when signal intensity is increased because of drift. The accuracy was improved in many cases when flicker correction was used, but when accurate results were obtained despite drift, the correction procedures did not reduce accuracy. The procedure may be useful to extract results from experimental runs that would otherwise have to be run again.
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9.
  • Cornelis, Geert (författare)
  • Effect of deposition, detachment and aggregation processes on nanoparticle transport in porous media using Monte Carlo simulations
  • 2021
  • Ingår i: Environmental Science: Nano. - : Royal Society of Chemistry (RSC). - 2051-8153 .- 2051-8161. ; , s. 2223-2234
  • Tidskriftsartikel (refereegranskat)abstract
    • A novel off-lattice three-dimensional coarse-grained Monte Carlo model is developed to study engineered nanoparticle (ENP) behavior in porous media. Based on individual particle tracking and on the assumption that different physicochemical processes may occur with different probabilities, our model is used to independently evaluate the influence of homoaggregation, attachment and detachment processes on ENP transport and retention inside porous media made of colloidal collectors. The possibility of straining, i.e. trapping of ENPs or aggregates that are too large to pass pore necks, is also included in the model. The overall probability of ENP retention as a function of the above mentioned processes is quantified using functional tests in the form of a alpha(global)(t(ref)) retention parameter. High alpha(global)(t(ref)) values were obtained for moderate probabilities of homoaggregation between ENPs (alpha(ENP-ENP)) and very small probabilities of attachment between ENPs and collectors (alpha(att)), thus indicating the important role of homoaggregation and attachment in ENP retention. Moreover, attaching ENPs and large aggregates was found to cause pore neck enclosure and thus largely contributed to the straining of unbound ENPs. An analysis of depth distribution of retained ENPs revealed that, depending on the dominating conditions, the number of ENPs was decreasing monotonously or exponentially with depth. The introduction of the ENP detachment probability (alpha(det)) from collectors resulted in an increased ENP occurrence at the porous media matrix outlet. It was also found that different sets of alpha(det) and alpha(att) values, reflecting different ENPs and collector physicochemical properties and inter-particle forces, lead to identical alpha(global)(t(ref)) values. This constitutes an important outcome indicating that alpha(global)(t(ref)) values determined from functional tests are not mechanistic but operationally defined parameters and thus cannot be deemed predictive beyond these tests.
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10.
  • Cornelis, Geert (författare)
  • Effect of soil properties on gold- and platinum nanoparticle mobility
  • 2017
  • Ingår i: Chemical Geology. - : Elsevier BV. - 0009-2541 .- 1872-6836. ; 466, s. 446-453
  • Tidskriftsartikel (refereegranskat)abstract
    • Soils overlying buried gold (Au) and platinum (Pt) deposits are often Au/Pt-anomalous, widening exploration footprints. This may be a result of the dispersion of (bio) geochemically formed Au/Pt nanoparticles and their sorption/deposition by solid soil phases. However, the influence of soil properties on nanoparticle dispersion, sorption and partitioning are little understood. To assess the partitioning and sorption behaviour of Au- and Pt nanoparticles, soils were spiked with spherical, citrate-stabilized Au- and Pt nanoparticles (diameter: 10-12 nm, final concentration 100 mu g kg(-1)). Soil slurries (1:10, w:w, soil: deionized water) were incubated at 22 degrees C on an end-over-end shaker for 28 days. Gold/Pt concentrations were measured in 0.45 mu m and 1 kDa filtered solutions using inductively coupled plasma-mass spectrometry. Neither Pt nor Au were detected in 1 kDa filtrates. Between 10.3 and 98.7 wt% of Au/Pt was sorbed to solid soil phases. Clay, C-org, Mg, Mn, Fe and Ca contents of soils were significant predictors of Au/Pt-nanoparticle sorption, with clay content explaining > 80% of variation within the Au sorption dataset. Partitioning of sorbed nanoparticles between solid phases was assessed using selective sequential extractions. In all soils 1-20 wt% of Au/Pt was detected in watery extracts. A further 1-25 wt% were associated with the easily remobilizable fraction. The majority of sorbed Au/Pt nanoparticles were sorbed to the organic matter (OM, 53-77 wt% for Pt and 14-80 wt% for Au) and the Fe/Mn-oxides (up to 42 wt%). These results show that: i) Au- and Pt nanoparticles are stable and can remain highly mobile/dispersible in soil solutions, and ii) elevated clay, C-org and Fe/Mn-oxide contents decrease, whereas elevated sand contents and pH increase their mobility. Across all soils, OM and clays were the most important sorbent of Au/Pt nanoparticles, suggesting that the separation of clays and OM, and analyses of their Au/Pt-contents may enhance the contrast of geochemical footprints.
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11.
  • Cornelis, Geert, 1978, et al. (författare)
  • Fate and Bioavailability of Engineered Nanoparticles in Soils: A Review
  • 2014
  • Ingår i: Critical Reviews in Environmental Science and Technology. - : Informa UK Limited. - 1064-3389 .- 1547-6537. ; 44:24, s. 2720-2764
  • Tidskriftsartikel (refereegranskat)abstract
    • Interactions within natural soils have often been neglected when assessing fate and bioavailability of engineered nanomaterials (ENM) in soils. This review combines patchwise ENM research using natural soils with the much wider literature on ENM performed in standard tests or on the fate of colloids in soils, and an analysis of the diverse ENM characteristics determining availability from the soil organisms' perspective to assess the main soil characteristics that determine the fate, speciation, and ultimately bioavailability of ENM in natural soils. Predominantly salinity, texture, pH, concentration, and nature of mobile organic compounds and degree of saturation determine ENM bioavailability.
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12.
  • Cornelis, Geert, 1978 (författare)
  • Fate descriptors for engineered nanoparticles: the good, the bad, and the ugly
  • 2015
  • Ingår i: Environmental science: Nano. - 2051-8153 .- 2051-8153. ; 1:2, s. 19-26
  • Tidskriftsartikel (refereegranskat)abstract
    • Developments in hazard identification of engineered nanoparticles (ENP) have not been met with proper fate descriptors to calculate travel distances and the bioavailable concentration of ENP. Three possible fate descriptors for ENP in soils are compared – batch partitioning coefficients (Kd values), batch retention coefficients (Kr values) and column attachment efficiency – in view of both technical and practical aspects of environmental risk assessments of ENP. Kd values are deemed not appropriate fate descriptors for ENP because the equilibrium assumption is not valid. The kinetic interpretation of batch studies offered by Kr values bears a link to relevant ENP processes in the environment, but interpretation may be confounded by the conditions of high shear during batch tests complicating direct use in transport or bioavailability calculations. Column experiments are, to some extent, also operationally defined and require a more experimentally dedicated approach that does not necessarily lead to a widely carrying physical parameter. Future efforts should therefore be investigated in development of tests that strike a better balance between operational simplicity and technical accuracy.
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13.
  • Cornelis, Geert (författare)
  • Harmonizing across environmental nanomaterial testing media for increased comparability of nanomaterial datasets
  • 2020
  • Ingår i: Environmental Science: Nano. - : Royal Society of Chemistry (RSC). - 2051-8153 .- 2051-8161. ; 7, s. 13-36
  • Tidskriftsartikel (refereegranskat)abstract
    • The chemical composition and properties of environmental media determine nanomaterial (NM) transport, fate, biouptake, and organism response. To compare and interpret experimental data, it is essential that sufficient context be provided for describing the physical and chemical characteristics of the setting in which a nanomaterial may be present. While the nanomaterial environmental, health and safety (NanoEHS) field has begun harmonization to allow data comparison and re-use (e.g. using standardized materials, defining a minimum set of required material characterizations), there is limited guidance for standardizing test media. Since most of the NM properties driving environmental behaviour and toxicity are medium-dependent, harmonization of media is critical. A workshop in March 2016 at Duke University identified five categories of test media: aquatic testing media, soil and sediment testing media, biological testing media, engineered systems testing media and product matrix testing media. For each category of test media, a minimum set of medium characteristics to report in all NM tests is recommended. Definitions and detail level of the recommendations for specific standardized media vary across these media categories. This reflects the variation in the maturity of their use as a test medium and associated measurement techniques, variation in utility and relevance of standardizing medium properties, ability to simplify standardizing reporting requirements, and in the availability of established standard reference media. Adoption of these media harmonization recommendations will facilitate the generation of integrated comparable datasets on NM fate and effects. This will in turn allow testing of the predictive utility of functional assay measurements on NMs in relevant media, support investigation of first principles approaches to understand behavioral mechanisms, and support categorization strategies to guide research, commercial development, and policy.
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14.
  • Cornelis, Geert (författare)
  • Impact of Ag2S NPs on soil bacterial community - A terrestrial mesocosm approach
  • 2020
  • Ingår i: Ecotoxicology and Environmental Safety. - : Elsevier BV. - 0147-6513 .- 1090-2414. ; 206
  • Tidskriftsartikel (refereegranskat)abstract
    • Soils might be a final sink for Ag2S nanoparticles (NPs). Still, there are limited data on their effects on soil bacterial communities (SBC). To bridge this gap, we investigated the effects of Ag2S NPs (10 mg kg(-1) soil) on the structure and function of SBC in a terrestrial indoor mesocosm, using a multi-species design. During 28 days of exposure, the SBC function-related parameters were analysed in terms of enzymatic activity, community level physiological profile, culture of functional bacterial groups [phosphorous-solubilizing bacteria (P-SB) and heterotrophic bacteria (HB)], and SBC structure was analysed by 16S rRNA gene-targeted denaturing gradient gel electrophoresis.The SBC exposed to Ag2S NPs showed a significative decrease of functional parameters, such as p-glucosidase activity and L-arginine consumption, and increase of the acid phosphatase activity. At the structural level, significantly lower richness and diversity were detected, but at later exposure times compared to the AgNO3 treatment, likely because of a low dissolution rate of Ag2S NPs. In fact, stronger effects were observed in soils spiked with AgNO3, in both functional and structural parameters. Changes in SBC structure seem to negatively correlate with parameters related to phosphorous (acid phosphatase activity) and carbon cycling (abundance of HB, P-SB, and beta-glucosidase activity). Our results indicate a significant effect of Ag2S NPs on SBC, specifically on parameters related to carbon and phosphorous cycling, at doses as low as 10 mg kg soil. These effects were only observed after 28 days, highlighting the importance of long-term exposure experiments for slowly dissolving NPs.
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15.
  • Cornelis, Geert (författare)
  • Key principles and operational practices for improved nanotechnology environmental exposure assessment
  • 2020
  • Ingår i: Nature Nanotechnology. - : Springer Science and Business Media LLC. - 1748-3387 .- 1748-3395. ; 15, s. 731-742
  • Forskningsöversikt (refereegranskat)abstract
    • Nanotechnology is identified as a key enabling technology due to its potential to contribute to economic growth and societal well-being across industrial sectors. Sustainable nanotechnology requires a scientifically based and proportionate risk governance structure to support innovation, including a robust framework for environmental risk assessment (ERA) that ideally builds on methods established for conventional chemicals to ensure alignment and avoid duplication. Exposure assessment developed as a tiered approach is equally beneficial to nano-specific ERA as for other classes of chemicals. Here we present the developing knowledge, practical considerations and key principles need to support exposure assessment for engineered nanomaterials for regulatory and research applications.The operationalization and improvement of environmental exposure assessment models for engineered nanomaterials can build on ten emerging principles relating to their release pathways, waste handling, transformations, influence of the properties on reactions and role that organisms can play in their fate and transport.
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16.
  • Cornelis, Geert (författare)
  • Nanomaterials as soil pollutants
  • 2018
  • Ingår i: Soil pollution : from monitoring to remediation. - 9780128498736 ; , s. 161-190
  • Bokkapitel (övrigt vetenskapligt/konstnärligt)
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17.
  • Cornelis, Geert (författare)
  • Occurrence, behaviour and effects of inorganic nanoparticles in the environment
  • 2021
  • Ingår i: Analysis and characterisation of metal-based nanomaterials. - : Elsevier. - 9780323853057 ; 93:93, s. 1-34
  • Bokkapitel (refereegranskat)abstract
    • Research in environmental risk assessment (ERA) of nanomaterials (NMs) has been an important incentive to develop analytical approaches to better understand and quantify fate and ecotoxicity of these materials in standard media and field environmental samples. This chapter presents and overview of the most recent insights in fate and ecotoxicity of NMs to steer analytical chemists to the most pressing analytical needs to further ERA of NMs thus avoid making it overly conservative. Sensitive analysis is required to quantify and characterize NMs at generally low expected concentrations (μg L− 1 to ng L− 1 range). Moreover, analysis of the core NM composition is required because many NMs are subject to transformation reactions in the environment, which in turn affects their fate and ecotoxicity. At the very minimum, dissolution of the NMs should be quantified, especially during standard ecotoxicity assays, while mesocosm-scale experiments have revealed unexpected NM behaviour that otherwise does not appear from standard tests. Finally, databases of relevant fate descriptors need development to aid NM fate prediction, similarly to soluble contaminants.
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18.
  • Cornelis, Geert (författare)
  • Polyphosphates and Fulvates Enhance Environmental Stability of PO4-Bearing Colloidal Iron Oxyhydroxides
  • 2016
  • Ingår i: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 64, s. 8465-8473
  • Tidskriftsartikel (refereegranskat)abstract
    • Iron oxyhydroxide nanoparticles (Fe-NPs) are natural vectors of phosphate (PO4) in the environment. Their mobility is determined by colloidal stability, which is affected by surface composition. This might be manipulated in engineered NPs for environmental or agricultural applications. Here, the stability of PO4-Fe-NPs (HFO/goethite) was determined across contrasting environmental conditions (pH, Ca concentration) and by using fulvates (FA) and polyphosphates (poly-P's) as coatings. The PO4-Fe-NPs are unstable at Ca concentrations above 0.1 mM. Addition of FA and some poly-P's significantly improved stability. Zeta potential explained colloidal stability across treatments; surface charge was calculated with surface complexation models and explained for phytic acid (PA) and hexametaphosphate (HMP) by a partial (1-4 of the 6 PO4 units) adsorption to the surface, while the remaining PO4 units stayed in solution. This study suggests that Ca concentration mainly affects the mobility of natural or engineered PO4-Fe-NPs and that HMP is a promising agent for increasing colloidal stability.
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19.
  • Cornelis, Geert (författare)
  • Secondary gold structures: Relics of past biogeochemical transformations and implications for colloidal gold dispersion in subtropical environments
  • 2017
  • Ingår i: Chemical Geology. - : Elsevier BV. - 0009-2541 .- 1872-6836. ; 450, s. 154-164
  • Tidskriftsartikel (refereegranskat)abstract
    • Biogeochemical processes are known to drive the cycling of gold via dissolution/re-precipitation reactions that result in the transformation of gold grain in near-surface environments. In this study, placer gold grains were collected from West Coast Creek, Queensland, Australia and characterized using high-resolution electron microscopy. The outer surface of grains contains 98.1 mol%Au and 1.9 mol%Ag. Crevices occur on the surface of grains and are filled with organics and clay minerals in which nanometer-size gold colloids and micrometer-sized octahedral gold platelets are embedded. The formation of these secondary gold structures is attributed to gold precipitation by the availability of reducing agents such as microbiota, residual organics and clays. Bacterioform gold contains 74.7 mol%Au and 25.3 mol% Ag and is also embedded in clay minerals within crevices. From sonicated gold grains, grain surfaces beneath the clay minerals are striated and contain 68.5mol%Au and 31.5mol%Ag. This data suggests that dissolution processes occur at the gold grain interface. Varying sizes of gold colloids on the grains suggest that five 'episodes' of gold dissolution/re-precipitation processes occurred; each episode was estimated to be 7.64 +/- 4.1 years. Therefore, these grains represent 17.9-58.5 years of gold cycling and mobilization within this subtropical environment. Furthermore, laboratory experiments involving colloidal gold dispersion demonstrated that iron-oxides and organic material from West Coast Creek sediment adsorbed 94.5% of suspended gold colloids. In conclusion, this study highlights the value of nanophase gold characterization for the interpretation of biogeochemical processes affecting gold grain transformation and mobility in near-surface environments. Importantly, this study is the first to estimate the kinetics of biogeochemical gold cycling with regards to colloidal gold dispersion and re-concentration.(C) 2016 Elsevier B.V. All rights reserved.
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20.
  • Cornelis, Geert (författare)
  • Sludge concentration, shear rate and nanoparticle size determine silver nanoparticle removal during wastewater treatment
  • 2017
  • Ingår i: Environmental Science: Nano. - 2051-8153 .- 2051-8161. ; 4, s. 2225-2234
  • Tidskriftsartikel (refereegranskat)abstract
    • Wastewater treatment (WWT) is generally efficient in removing nanoparticles (NPs) from sewage effluent, but the variety in removal rates has not yet been explained. WWT parameters such as the activated sludge (AS) concentration, shear rate and ionic strength were varied in kinetic batch attachment and sedimentation studies using silver NPs having nominal 20 or 80 nm sizes and citrate or PEG coatings. The fitted attachment and detachment rate constants and the resulting distribution ratios at steady state varied with WWT process parameters, but most notably with the NP size, which was also found to influence the settling rates most. The NP coating molecules had a limited or no effect. A meta-analysis of literature distribution ratios (attached/detached concentration) of NPs composed of Ag and other materials showed the NP (aggregate) size as the only significant parameter. However, while the distribution ratio of silver NPs to AS increased linearly with AS concentration, the final effect of NP effluent concentrations is partly offset by decreased sedimentation rates. The results thus confirm that a WWT process is efficient in removing NPs from wastewater, but relatively small (<20 nm) non-aggregated NPs are somewhat more likely to exit a WWT process via the effluent into aquatic compartments compared to relatively larger NPs, which nearly entirely leave the WWT plants with the AS towards soils, incineration plants or landfills.
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21.
  • Cornelis, Geert, et al. (författare)
  • Solubility and transport of Cr(III) in a historically contaminated soil – Evidence of a rapidly reacting dimeric Cr(III) organic matter complex
  • 2017
  • Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 189, s. 709-716
  • Tidskriftsartikel (refereegranskat)abstract
    • Chromium is a common soil contaminant and, although it has been studied widely, questions about its speciation and dissolutions kinetics remain unanswered. We combined information from an irrigation experiment performed with intact soil columns with data from batch experiments to evaluate solubility and mobilization mechanisms of Cr(III) in a historically contaminated soil (>65 years). Particulate and colloidal Cr(III) forms dominated transport in this soil, but their concentrations were independent of irrigation intensity (2-20 mm h(-1)). Extended X-ray absorption fine structure (EXAFS) measurements indicated that Cr(III) associated with colloids and particles, and with the solid phase, mainly existed as dimeric hydrolyzed Cr(III) bound to natural organic matter. Dissolution kinetics of this species were fast (<= 1 day) at low pH (<3) and slightly slower (<= 5 days) at neutral pH. Furthermore, it proved possible to describe the solubility of the dimeric Cr(III) organic matter complex with a geochemical equilibrium model using only generic binding parameters, opening the way for use of geochemical models in risk assessments of Cr(III)-contaminated sites. (C) 2017 The Authors. Published by Elsevier Ltd.
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22.
  • Cornelis, Geert (författare)
  • TiO2 nanomaterial detection in calcium rich matrices by spICPMS. A matter of resolution and treatment
  • 2017
  • Ingår i: Journal of Analytical Atomic Spectrometry. - 0267-9477. ; 32, s. 1400-1411
  • Tidskriftsartikel (refereegranskat)abstract
    • High Ca concentrations in complex matrices such as river waters often hamper the detection of titanium nanomaterials (TiO2 NPs) by single particle inductively coupled plasma mass spectrometry (spICPMS), because of isobaric interference of Ca-48 on the most abundant Ti isotope (Ti-48). Several approaches were used to reduce this interference while measuring TiO2 in solutions with different Ca concentrations up to 100 mg L-1. ICP-MS/MS was used with ammonia as the reaction ceLL gas and high resoLution (HR) ICP-MS was used under different resoLution settings. These approaches were compared by measuring different Ti isotopes (Ti-47 and Ti-49). spICPMS data were then treated with a deconvoLution method to filter out dissolved signals and identify the best approach to detect the Lowest possible corresponding spherical size of TiO2 NPs (D,in). ICP-MS/MS aLLowed for an important decrease of the theoretical D-min compared to standard quadrupole ICP-MS, down to 64 nm in uLtrapure water; however the sensitivity was reduced by the reaction gas and increasing Ca concentrations also increased the D-min. The comparably higher sensitivity of HR-ICP-MS aLLowed for theoretically measuring a D-min of 10 nm in uLtrapure water. Combined with the deconvoLution analysis, the highest resoLution mode in HR-ICP-MS Leads to the Lowest D-min at high Ca concentrations, even though significant broadening of the measured mass distributions occurred for TiO2 NPs at Ca concentrations up to 100 mg L-1.
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23.
  • Cornelis, Geert (författare)
  • Toxicokinetics of Ag from Ag2S NP exposure in Tenebrio molitor and Porcellio scaber: Comparing single-species tests to indoor mesocosm experiments
  • 2023
  • Ingår i: NanoImpact. - : Elsevier BV. - 2452-0748. ; 29
  • Tidskriftsartikel (refereegranskat)abstract
    • Determining the potential for accumulation of Ag from Ag2S NPs as an environmentally relevant form of AgNPs in different terrestrial organisms is an essential component of a realistic risk assessment of AgNP emissions to soils. The objectives of this study were first to determine the uptake kinetics of Ag in mealworms (Tenebrio molitor) and woodlice (Porcellio scaber) exposed to Ag2S NPs in a mesocosm test, and second, to check if the obtained toxicokinetics could be predicted by single-species bioaccumulation tests. In the mesocosms, meal-worms and woodlice were exposed together with plants and earthworms in soil columns spiked with 10 mu g Ag g(-1) dry soil as Ag2S NPs or AgNO3. The total Ag concentrations in the biota were measured after 7, 14, and 28 days of exposure. A one-compartment model was used to calculate the Ag uptake and elimination rate constants. Ag from Ag2S NPs appeared to be taken up by the mealworms with significantly different uptake rate constants in the mesocosm compared to single-species tests (K-1 = 0.056 and 1.66 g dry soil g(-1) dry body weight day(-1), respectively), and a significant difference was found for the Ag bioaccumulation factor (BAFk = 0.79 and 0.15 g dry soil g(-1) dry body weight, respectively). Woodlice did not accumulate Ag from Ag2S NPs in both tests, but uptake from AgNO3 was significantly slower in mesocosm than in single-species tests (K-1 = 0.037 and 0.26 g dry soil g(-1) dry body weight day(-1), respectively). Our results are of high significance because they show that single-species tests may not be a good predictor for the Ag uptake in mealworms and woodlice in exposure systems having greater levels of biological complexity. Nevertheless, single-species tests could be used as a fast screening approach to assess the potential of a substance to accumulate in biota before more complex tests are conducted.
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24.
  • Cornelis, Geert (författare)
  • Where is the nano? Analytical approaches for the detection and quantification of TiO2 engineered nanoparticles in surface waters
  • 2018
  • Ingår i: Environmental Science: Nano. - : Royal Society of Chemistry (RSC). - 2051-8153 .- 2051-8161. ; 5, s. 313-326
  • Tidskriftsartikel (refereegranskat)abstract
    • Detecting and quantifying engineered nanoparticles (ENPs) in complex environmental matrices requires the distinction between natural nanoparticles (NNPs) and ENPs. The distinction of NNPs and ENPs for regulatory purposes calls for cost-efficient methods, but is hampered by similarities in intrinsic properties, such as particle composition, size, density, surface chemistry, etc. Titanium dioxide (TiO2) ENPs, for instance, are produced in very large quantities but Ti also commonly occurs naturally in nano-scale minerals. In this work, we focus on utilizing particle size and composition to identify ENPs in a system with a significant background concentration of the target metal. We have followed independent approaches involving both conventional and state-of-the-art analytical techniques to detect and quantify TiO2 ENPs released into surface waters from sunscreen products and to distinguish them from Ti-bearing NNPs. To achieve this, we applied single particle inductively coupled plasma mass spectrometry with single-element (spICPMS) and multi-element detection (time-of-flight) spICP-TOFMS, together with transmission electron microscopy (TEM), automated scanning electron microscopy (autoSEM), and bulk elemental analyses. A background concentration of Ti-bearing NPs (approximately 5 x 10(3) particles per ml), possibly of natural origin, was consistently observed outside the bathing season. This concentration increased by up to 40% during the bathing season. Multi-element analysis of individual particles using spICP-TOFMS revealed that Al, Fe, Mn, and Pb are often present in natural Ti-bearing NPs, but no specific multi-element signatures were detected for ENPs. Our data suggests that TiO2 ENPs enter the lake water during bathing activities, eventually agglomerating and sedimenting. We found adhesion of the TiO2 ENPs to the air-water interface for short time periods, depending on wind conditions. This study demonstrates that the use of spICP-TOFMS and spICPMS in combination with other conventional analytical techniques offers significant advantages for discriminating between NNPs and ENPs. The quantitative data produced in this work can be used as input for modeling studies or as a benchmark for analysis protocols and model validations.
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25.
  • Doolette, Casey L, et al. (författare)
  • Transformation of PVP coated silver nanoparticles in a simulated wastewater treatment process and the effect on microbial communities.
  • 2013
  • Ingår i: Chemistry Central Journal. - 1752-153X. ; 7:1
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: Manufactured silver nanoparticles (AgNPs) are one of the most commonly used nanomaterials in consumer goods and consequently their concentrations in wastewater and hence wastewater treatment plants are predicted to increase. We investigated the fate of AgNPs in sludge that was subjected to aerobic and anaerobic treatment and the impact of AgNPs on microbial processes and communities. The initial identification of AgNPs in sludge was carried out using transmission electron microscopy (TEM) with energy dispersive X-ray (EDX) analysis. The solid phase speciation of silver in sludge and wastewater influent was then examined using X-ray absorption spectroscopy (XAS). The effects of transformed AgNPs (mainly Ag-S phases) on nitrification, wastewater microbial populations and, for the first time, methanogenesis was investigated. RESULTS: Sequencing batch reactor experiments and anaerobic batch tests, both demonstrated that nitrification rate and methane production were not affected by the addition of AgNPs [at 2.5 mg Ag L-1 (4.9 g L-1 total suspended solids, TSS) and 183.6 mg Ag kg -1 (2.9 g kg-1 total solids, TS), respectively].The low toxicity is most likely due to AgNP sulfidation. XAS analysis showed that sulfur bonded Ag was the dominant Ag species in both aerobic (activated sludge) and anaerobic sludge. In AgNP and AgNO3 spiked aerobic sludge, metallic Ag was detected (~15%). However, after anaerobic digestion, Ag(0) was not detected by XAS analysis. Dominant wastewater microbial populations were not affected by AgNPs as determined by DNA extraction and pyrotag sequencing. However, there was a shift in niche populations in both aerobic and anaerobic sludge, with a shift in AgNP treated sludge compared with controls. This is the first time that the impact of transformed AgNPs (mainly Ag-S phases) on anaerobic digestion has been reported. CONCLUSIONS: Silver NPs were transformed to Ag-S phases during activated sludge treatment (prior to anaerobic digestion). Transformed AgNPs, at predicted future Ag wastewater concentrations, did not affect nitrification or methanogenesis. Consequently, AgNPs are very unlikely to affect the efficient functioning of wastewater treatment plants. However, AgNPs may negatively affect sub-dominant wastewater microbial communities.
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26.
  • Doolette, C. L., et al. (författare)
  • Transformation of PVP coated silver nanoparticles in a simulated wastewater treatment process and the effect on microbial communities
  • 2013
  • Ingår i: Chemistry Central Journal. - : Springer Science and Business Media LLC. - 1752-153X. ; 7:46
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Manufactured silver nanoparticles (AgNPs) are one of the most commonly used Results: Sequencing batch reactor experiments and anaerobic batch tests, both demonstrated that The low toxicity is most likely due to AgNP sulfidation. XAS analysis showed that sulfur bonded Ag was Conclusions: Silver NPs were transformed to Ag-S phases during activated sludge treatment (prior to
  •  
27.
  • Folens, K., et al. (författare)
  • Identification of platinum nanoparticles in road dust leachate by single particle inductively coupled plasma-mass spectrometry
  • 2018
  • Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 615, s. 849-856
  • Tidskriftsartikel (refereegranskat)abstract
    • Elevated platinum (Pt) concentrations are found in road dust as a result of emissions from catalytic converters in vehicles. This study investigates the occurrence of Pt in road dust collected in Ghent (Belgium) and Gothenburg (Sweden). Total Pt contents, determined by tandem ICP-mass spectrometry (ICP-MS/MS), were in the range of 5 to 79 ng g − 1 , comparable to the Pt content in road dust of other medium-sized cities. Further sample characterization was performed by single particle (sp) ICP-MS following an ultrasonic extraction procedure using stormwater runoff for leaching. The method was found to be suitable for the characterization of Pt nanoparticles in road dust leachates. The extraction was optimized using road dust reference material BCR-723, for which an extraction efficiency of 2.7% was obtained by applying 144 kJ of ultrasonic energy. Using this method, between 0.2% and 18% of the Pt present was extracted from road dust samples. spICP-MS analysis revealed that Pt in the leachate is entirely present as nanoparticles of sizes between 9 and 21 nm. Although representing only a minor fraction of the total content in road dust, the nanoparticulate Pt leachate is most susceptible to biological uptake and hence most relevant in terms of bioavailability.
  •  
28.
  • Formentini, Thiago, et al. (författare)
  • Immobilizing arsenic in contaminated anoxic aquifer sediment using sulfidated and uncoated zero-valent iron (ZVI)
  • 2024
  • Ingår i: Journal of Hazardous Materials. - 0304-3894 .- 1873-3336. ; 462
  • Tidskriftsartikel (refereegranskat)abstract
    • Arsenic (As) is carcinogenic and of major concern in groundwater. We collected sediment material from a contaminated anoxic aquifer in Sweden and investigated the immobilization of As by four commercial zero-valent iron (ZVI) particles. Solid-phase As and Fe speciation was assessed using X-ray absorption spectroscopy (XAS) and solution-phase As speciation using chromatographic separation. Without ZVI addition, arsenite dominated in solution and As(V) species in the solid phase. Adding ZVI caused a sharp increase in solution pH (9.3-9.8), favoring As oxidation despite a lowered redox potential. ZVI greatly improved As retention by complex binding of arsenate to the Fe(III) (hydr)oxides formed by ZVI corrosion. Uncoated ZVI, both in nano-and microscale, performed better than their sulfidated counterparts, partly due to occlusion of As by the Fe(III) (hydr) oxides formed. The effect of particle size (micro vs. nano ZVI) on As immobilization was small, likely because immobilization was related to the corrosion products formed, rather than the initial size of the particles. Our results provide a strong geochemical background for the application of ZVI particles to remove As in contaminated aquifers under anoxic conditions and illustrate that immobilization mechanisms can differ between ZVI in As spiked solutions and sediment suspensions.Environmental implication: Arsenic ranks first on the list by the US ATSDR of substances posing a threat to human health and the WHO considers groundwater the riskiest source for human intake of As. However, dealing with As contamination remains a scientific challenge. We studied the immobilization of groundwater As by commercially available ZVI particles at field-realistic conditions. Arsenic immobilization was highly efficient in most cases, and the results suggest this is a promising in situ strategy with long-term performance. Our results provide a strong geochemical background for using ZVI to remove As in contaminated anoxic aquifers.
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29.
  • Gallego-Urrea, Julian A., 1977, et al. (författare)
  • Coagulation and sedimentation of gold nanoparticles and illite in model natural waters: Influence of initial particle concentration
  • 2016
  • Ingår i: NanoImpact. - : Elsevier BV. - 2452-0748. ; 3-4, s. 67-74
  • 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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30.
  • Gallego-Urrea, Julian A., 1977, et al. (författare)
  • Multimethod 3D characterization of natural plate-like nanoparticles: shape effects on equivalent size measurements
  • 2014
  • Ingår i: Journal of nanoparticle research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 16:5
  • 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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31.
  • Heinze, Wiebke Mareile, et al. (författare)
  • Nanoplastic Transport in Soil via Bioturbation by Lumbricus terrestris
  • 2021
  • Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 55, s. 16423-16433
  • Tidskriftsartikel (refereegranskat)abstract
    • Plastic pollution is increasingly perceived as an emerging threat to terrestrial environments, but the spatial and temporal dimension of plastic exposure in soils is poorly understood. Bioturbation displaces microplastics (>1 mu m) in soils and likely also nanoplastics (<1 mu m), but empirical evidence is lacking. We used a combination of methods that allowed us to not only quantify but to also understand the mechanisms of biologically driven transport of nanoplastics in microcosms with the deep-burrowing earthworm Lumbricus terrestris. We hypothesized that ingestion and subsurface excretion drives deep vertical transport of nanoplastics that subsequently accumulate in the drilosphere, i.e., burrow walls. Significant vertical transport of palladium-doped polystyrene nanoplastics (diameter 256 nm), traceable using elemental analysis, was observed and increased over 4 weeks. Nanoplastics were detected in depurated earthworms confirming their uptake without any detectable negative impact. Nanoplastics were indeed enriched in the drilosphere where cast material was visibly incorporated, and the reuse of initial burrows could be monitored via X-ray computed tomography. Moreover, the speed of nanoplastics transport to the deeper soil profile could not be explained with a local mixing model. Earthworms thus repeatedly ingested and excreted nanoplastics in the drilosphere calling for a more explicit inclusion of bioturbation in nanoplastic fate modeling under consideration of the dominant mechanism. Further investigation is required to quantify nanoplastic re-entrainment, such as during events of preferential flow in burrows.
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32.
  • Heinze, Wiebke Mareile, et al. (författare)
  • Vertical distribution of microplastics in an agricultural soil after long-term treatment with sewage sludge and mineral fertiliser
  • 2024
  • Ingår i: Environmental Pollution. - 0269-7491 .- 1873-6424. ; 356
  • Tidskriftsartikel (refereegranskat)abstract
    • Sewage sludge applications release contaminants to agricultural soils, such as potentially toxic metals and microplastics (MPs). However, factors determining the subsequent mobility of MPs in long-term field conditions are poorly understood. This study aimed to understand the vertical distribution of MPs in soils amended with sewage sludge in comparison to conventional mineral fertiliser for 24 years. The depth-dependent MP mass and number concentrations, plastic types, sizes and shapes were compared with the distribution of organic carbon and metals to provide insights into potentially transport-limiting factors. Polyethylene, polypropylene and polystyrene mass concentrations were screened down to 90 cm depth via pyrolysis-gas chromatography/mass spectrometry. MP number concentrations, additional plastic types, sizes, and shapes were analysed down to 40 cm depth using micro-Fourier transform-infrared imaging. Across all depths, MP numbers were twice and mass concentrations 8 times higher when sewage sludge was applied, with a higher share of textile-related plastics, more fibres and on average larger particles than in soil receiving mineral fertiliser. Transport of MPs beyond the plough layer (0-20 cm) is often assumed negligible, but substantial MP numbers (42 %) and mass (52 %) were detected down to 70 cm in sewage sludge-amended soils. The initial mobilization of MPs was shape- and sizedependent, because the fractions of fragmental-shaped and relatively small MPs increased directly below the plough layer, but not at greater depths. The sharp decline of total MP concentrations between 20 and 40 cm depth resembled that of metals and organic matter suggesting similar transport limitations. We hypothesize that the effect of soil management, such as ploughing, on soil compactness and subsequent transport by bioturbation and via macropores drives vertical MP distribution over long time scales. Risk assessment in soils should therefore account for considerable MP displacement to avoid underestimating soil exposure.
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33.
  • In ’t Veld, Sjors G.J.G., et al. (författare)
  • Detection and localization of early- and late-stage cancers using platelet RNA
  • 2022
  • Ingår i: Cancer Cell. - : Elsevier. - 1535-6108 .- 1878-3686. ; 40:9, s. 999-1009.e6
  • Tidskriftsartikel (refereegranskat)abstract
    • Cancer patients benefit from early tumor detection since treatment outcomes are more favorable for less advanced cancers. Platelets are involved in cancer progression and are considered a promising biosource for cancer detection, as they alter their RNA content upon local and systemic cues. We show that tumor-educated platelet (TEP) RNA-based blood tests enable the detection of 18 cancer types. With 99% specificity in asymptomatic controls, thromboSeq correctly detected the presence of cancer in two-thirds of 1,096 blood samples from stage I–IV cancer patients and in half of 352 stage I–III tumors. Symptomatic controls, including inflammatory and cardiovascular diseases, and benign tumors had increased false-positive test results with an average specificity of 78%. Moreover, thromboSeq determined the tumor site of origin in five different tumor types correctly in over 80% of the cancer patients. These results highlight the potential properties of TEP-derived RNA panels to supplement current approaches for blood-based cancer screening.
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34.
  • Kookana, Rai, et al. (författare)
  • Nanopesticides: Guiding principles for regulatory evaluation of environmental risks
  • 2014
  • Ingår i: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 62:19, s. 4227-4240
  • Tidskriftsartikel (refereegranskat)abstract
    • Nanopesticides or nano plant protection products represent an emerging technological development that, in relation to pesticide use, could offer a range of benefits including increased efficacy, durability, and a reduction in the amounts of active ingredients that need to be used. A number of formulation types have been suggested including emulsions (e.g., nanoemulsions), nanocapsules (e.g., with polymers), and products containing pristine engineered nanoparticles, such as metals, metal oxides, and nanoclays. The increasing interest in the use of nanopesticides raises questions as to how to assess the environmental risk of these materials for regulatory purposes. Here, the current approaches for environmental risk assessment of pesticides are reviewed and the question of whether these approaches are fit for purpose for use on nanopesticides is addressed. Potential adaptations to existing environmental risk assessment tests and procedures for use with nanopesticides are discussed, addressing aspects such as analysis and characterization, environmental fate and exposure assessment, uptake by biota, ecotoxicity, and risk assessment of nanopesticides in aquatic and terrestrial ecosystems. Throughout, the main focus is on assessing whether the presence of the nanoformulation introduces potential differences relative to the conventional active ingredients. The proposed changes in the test methodology, research priorities, and recommendations would facilitate the development of regulatory approaches and a regulatory framework for nanopesticides.
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35.
  • Löv, Åsa, et al. (författare)
  • Evaluating the ability of standardised leaching tests to predict metal(loid) leaching from intact soil columns using size-based elemental fractionation
  • 2019
  • Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 222, s. 453-460
  • Tidskriftsartikel (refereegranskat)abstract
    • Laboratory-based leaching tests are frequently used for in situ risk assessments of contaminant leaching to groundwater and surface waters. This study evaluated the ability of three standardised leaching tests to assess leaching of lead (Pb), zinc (Zn), arsenic (As) and antimony (Sb) from four intact soil profiles, by considering particulate (0.45-8 mu m; percolation test), colloidal (10 kDa-0.45 mu m) and truly dissolved (<10 kDa) fractions of these elements. Deionised water was used as the percolation test leachant, while either deionised water or 1 mM CaCl2 was used in batch tests. Data from an irrigation experiment were used as reference. The results indicated that in percolation tests, leachate should be collected at a liquid:solid ratio (L/S) range of 2-10, instead of 0-0.5 or 0.5-2. Even at L/S = 2-10, the percolation test overestimated total Pb concentration, mainly because of greater mobilisation of particle-bound Pb, but appeared suitable for categorising soils into high/low risk with respect to mobilisation of particulate and colloidal contaminants. The batch test performed better with CaCl2 than with deionised water when standard membrane filtration (0.45 gm) was used, as the high Ca2+ concentration reduced colloidal mobilisation, avoiding overestimation of concentrations of elements such as Pb. However, the higher Ca2+ concentration and lower pH could result in overestimated concentrations of weakly sorbed elements, e.g. Zn. (C) 2019 The Authors. Published by Elsevier Ltd.
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36.
  • Löv, Åsa, et al. (författare)
  • Particle- and colloid-facilitated Pb transport in four historically contaminated soils - Speciation and effect of irrigation intensity
  • 2018
  • Ingår i: Applied Geochemistry. - : Elsevier BV. - 0883-2927. ; 96, s. 327-338
  • Tidskriftsartikel (refereegranskat)abstract
    • Due to the low solubility of lead (Pb) in many soils, colloidal and particulate transport may have large effects on Pb leaching. However, the role of colloidal and particulate transport varies considerably between soils and the mechanisms controlling mobilisation are complex and poorly known. Furthermore, increased frequency of high-intensity rainfall events is expected in some parts of Europe and North America in response to climate change, which might increase the mobilisation of particles and colloids. In this work, we investigated transport of particulate ( > 0.45 mu m), colloidal (10 kDa-0.45 mu m) and truly dissolved ( < 10 kDa) Pb in an irrigation experiment on intact soil columns from four historically contaminated soils. We also investigated the effect of irrigation intensity (2-20 mmh(-1)) on Pb leaching in these fractions. The mechanism binding Pb on particles and colloids was evaluated by extended X-ray absorption fine structure (EXAFS) spectroscopy and geochemical modelling. A 10-fold increase in irrigation intensity brought about at most a three-fold change in leached particulate and colloidal Pb concentrations. In contrast, the fraction of leached Pb associated with particles and colloids varied by one order of magnitude between soils. Hence, the results suggest that it is more important to consider soil type than potential future increases in rainfall. For one soil with high concentrations of both arsenic (As) and Pb, geochemical modelling indicated that mimetite, Pb-5(AsO4)(3)Cl(s), was the major Pb species in the colloidal and particulate fractions. For the other three soils, EXAFS of Pb on isolated particles and colloids indicated that ferrihydrite was a major phase-sorbing Pb and this was supported by geochemical equilibrium modelling. Thus geochemical modelling can be used to indicate the speciation of Pb in particles and colloids leached in intact soils.
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37.
  •  
38.
  • Minelli, Caterina, et al. (författare)
  • Versailles project on advanced materials and standards (VAMAS) interlaboratory study on measuring the number concentration of colloidal gold nanoparticles
  • 2022
  • Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 14, s. 4690-4704
  • Tidskriftsartikel (refereegranskat)abstract
    • We describe the outcome of a large international interlaboratory study of the measurement of particle number concentration of colloidal nanoparticles, project 10 of the technical working area 34, "Nanoparticle Populations" of the Versailles Project on Advanced Materials and Standards (VAMAS). A total of 50 laboratories delivered results for the number concentration of 30 nm gold colloidal nanoparticles measured using particle tracking analysis (PTA), single particle inductively coupled plasma mass spectrometry (spICP-MS), ultraviolet-visible (UV-Vis) light spectroscopy, centrifugal liquid sedimentation (CLS) and small angle X-ray scattering (SAXS). The study provides quantitative data to evaluate the repeatability of these methods and their reproducibility in the measurement of number concentration of model nanoparticle systems following a common measurement protocol. We find that the population-averaging methods of SAXS, CLS and UV-Vis have high measurement repeatability and reproducibility, with between-labs variability of 2.6%, 11% and 1.4% respectively. However, results may be significantly biased for reasons including inaccurate material properties whose values are used to compute the number concentration. Particle-counting method results are less reproducibile than population-averaging methods, with measured between-labs variability of 68% and 46% for PTA and spICP-MS respectively. This study provides the stakeholder community with important comparative data to underpin measurement reproducibility and method validation for number concentration of nanoparticles.
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39.
  • Norrfors, Karin, et al. (författare)
  • A critical evaluation of short columns for estimating the attachment efficiency of engineered nanomaterials in natural soils
  • 2021
  • Ingår i: Environmental Science: Nano. - : Royal Society of Chemistry (RSC). - 2051-8153 .- 2051-8161.
  • Tidskriftsartikel (refereegranskat)abstract
    • Short, saturated packed columns are used frequently to estimate the attachment efficiency (alpha) of engineered nanomaterials (ENMs) in relatively homogeneous porous media, but a combined experimental and theoretical approach to obtain alpha-values for heterogeneous natural soils has not yet been agreed upon. Accurately determined alpha-values that can be used to study and predict ENM transport in natural soils should vary with ENM and soil properties, but not with experimental settings. We investigated the effect of experimental conditions, and used different methods to obtain soil parameters, essential to calculate alpha. We applied 150 different approaches to determine alpha-values from 52 transport experiments using short columns with 5 different natural soils and 20 and 80 nm gold- or 27 nm silver sulphide ENMs. The choice of column end-filter material and pore size appeared critical to avoid overestimating alpha owing to filter - ENM interactions and/or incomplete saturation of the column. Using a low ionic strength (4.4 x 10-5 mol L-1) artificial rain water as an aqueous medium avoided ENM homo- or heteroaggregation in all soils, as confirmed by single-particle inductively coupled plasma - time of flight mass spectrometry. ENM breakthrough curves could be modelled using colloid filtration theory assuming irreversible attachment only. alpha-Values calculated from this model, having the grain size represented by a single average size, accounting for dispersivity and effective porosity based on a prior inert tracer test, explained up to 42% of the variance in alpha as revealed by partial least squares analysis. However, column length and dispersivity remained as important experimental parameters, which calls for further standardisation efforts of column tests with ENMs in natural soils, preferably cross-validated with batch tests.
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40.
  • Norrfors, Karin, et al. (författare)
  • Tools and rules for modelling uptake and bioaccumulation of nanomaterials in invertebrate organisms
  • 2019
  • Ingår i: Environmental Science: Nano. - : Royal Society of Chemistry (RSC). - 2051-8153 .- 2051-8161. ; 6, s. 1985-2001
  • Forskningsöversikt (refereegranskat)abstract
    • Quantification of the uptake and elimination of nanomaterials (NMs) by organisms is key in assessing the environmental risks of NMs. For this, uptake models for conventional solutes may be used, although no consensus exists on their applicability for NMs. In this critical review therefore, conventional modelling approaches are scrutinised for their applicability for NMs. Statically derived accumulation factors, like BCF or BAF based on measured concentrations, are considered to be flawed because NMs are thermodynamically not stable, an important assumption for this approach. Dynamically derived accumulation factors, based on kinetic exposure experiments, may be applicable because no equilibrium between the organism and exposure medium is needed. Currently there is no full understanding of the passive uptake of NMs, which hampers assessment of the applicability of biotic ligand models. Passive uptake, however, is generally considered to be very limited, which would imply a limited applicability of BLMs for NMs. Physiologically based pharmacokinetic (PBPK) models, or biodynamic models, have successfully been applied in uptake studies with NMs. Their underlying assumptions can be met in experiments addressing NMs and case studies presented in this review demonstrate their applicability to model NM-form specific kinetics, integrated with environmental fate models, including relevant physiological processes. Their application requires the a priori definition of the major mechanisms driving the uptake kinetics and the quantification of the associated kinetic rate constants. This limits their application to those mechanisms for which the kinetic rate constants can actually be quantified. Within these limitations, PBPK models have been shown to be applicable and provide a promising general approach to improve modelling of NM-accumulation in organisms.
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41.
  • Nowack, Bernd, et al. (författare)
  • Progress towards the validation of modeled environmental concentrations of engineered nanomaterials by analytical measurements
  • 2015
  • Ingår i: Environmental Science: Nano. - 2051-8153. ; 2:5, s. 421-428
  • Tidskriftsartikel (refereegranskat)abstract
    • Environmental exposure modeling has been used extensively in the last years to obtain estimates of environmental concentrations of engineered nanomaterials (ENMs). In this perspective piece, we explore the issues when aiming to validate modeled environmental concentrations and propose options for both modelers and analytical chemists on how to proceed in the future to better compliment one another's efforts. In this context, validation means to determine the degree to which the simulation results from a model are accurate representations of the real world by comparison with analytical data. Therefore, for such a model validation procedure, analytical methods need to be available which provide information in the same subject area. Currently, a major issue with nanometrology is that a multitude of nanomaterials are present in natural systems but only some are ENMs; various other particles of natural origin are abundant in the same systems. The analytical tools available are not yet capable to distinguish the natural from engineered nanomaterials at the low ENM concentrations expected in complex environmental matrices. However, both modeling and analytical studies are able to provide an orthogonal view on nanomaterials: modeling is able to yield estimates of the presence of ENMs in various environmental compartments while analytics can provide physical characterization of ENMs in these systems with hints towards the total nanomaterial concentration. While we need to make strides to improve the two approaches separately, using the resulting data together in a mutually supportive way will advance the field of ENM risk assessment.
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42.
  • Peijnenburg, W., et al. (författare)
  • Fate assessment of engineered nanoparticles in solids dominated media - Current insights and the way forward
  • 2016
  • Ingår i: Environmental Pollution. - : Elsevier BV. - 0269-7491. ; 218, s. 1365-1369
  • Tidskriftsartikel (refereegranskat)abstract
    • Exposure assessment of engineered nanoparticles (ENPs) in soil and sediment is severely hampered by a lack of understanding of the underlying processes and of the impact of matrix constituents on the fate of ENPs in natural systems, including porewater properties like pH, ionic strength, and presence of naturally occurring (nano)particles. Additional issues such as lack of proper methods for in-situ assessment of ENP speciation, ENP ageing, and agglomeration state, hinder proper exposure assessment. Let alone that the lack does not allow for development of predictive methods for endpoints like transformation and agglomeration potential. This paper discusses current approaches for fate assessment of ENPs in solids dominated media and addresses the most prominent knowledge gaps and how these may be addressed. It is concluded that the key issue to be dealt with, are the attachment and deposition processes that are characteristic for ENPs as opposed to equilibrium-driven partitioning processes of non-particulate organic and inorganic contaminants.
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43.
  • Rodriguez-Iruretagoiena, Azibar, et al. (författare)
  • A new procedure to quantify silver nanoparticles in sediments
  • 2022
  • Ingår i: Gondwana Research. - : Elsevier BV. - 1342-937X .- 1878-0571. ; 110, s. 264-269
  • Tidskriftsartikel (refereegranskat)abstract
    • Silver nanoparticles (AgNPs) are highly produced in developed countries for a variety of products. Consequently, AgNPs end up being introduced in aquatic systems all over the world, and usually deposited in riverine sediments, from where they can be taken up by aquatic organisms and transferred along the food chain. The analysis of AgNPs in natural samples is not an easy task, because of their low presence and complicated reactions, which can change their speciation. The objective of this work is to help in this challenge, developing a method applicable to analyse sediment samples from any place around the world where AgNPs are suspected to be present. Firstly, four methods for the synthesis of AgNPs were investigated by Ultraviolet-visible (UV-VIS) spectroscopy and particle size analysis. The methods differed in the reducing agent used and in the concentration of the stabilising agent applied. The method including NaBH4 and SDS (sodium dodecyl sulphate) resulted to be more adequate as the Surface Plasmon Resonance (SPR) band position and width indicated. This conclusion was corroborated considering the hydrodynamic diameters and polydispersity indices of the synthesised AgNPs. The Z-average hydrodynamic diameter and the UV-VIS spectrum of AgNPs synthesised using this method indicated that the AgNPs remained kinetically stable for at least 10 days. Finally, ten potential extraction solutions were investigated, in terms of maximal extraction efficiency, but minimal effects on AgNP dissolution and aggregation. The candidate solutions ranged from deionized water and salts to strong acids and bases. The intensity of the SPR band concluded that using NaOH media the synthesised AgNPs was kinetically stable. Moreover, TEM (Transmission Electron Microscopy) images showed that the AgNPs in NaOH retained their shape and size after 10 days. Therefore, NaOH media turned out to be the best potential extractant for the analysis of sediment samples.
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44.
  • Tuoriniemi, Jani, 1982, et al. (författare)
  • A new peak recognition algorithm for detection of ultra-small nano-particles by single particle ICP-MS using rapid time resolved data acquisition on a sector-field mass spectrometer
  • 2015
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 30:8, s. 1723-1729
  • Tidskriftsartikel (refereegranskat)abstract
    • The applicability of single particle inductively coupled plasma mass spectrometry (spICPMS) is currently limited to particles larger than similar to 10 nm in diameter. In this work, the size detection limit (DLs) was improved by resolving the ion bursts originating from silver or gold nanoparticles (AgNPs or AuNPs) using real time data acquisition with 0.1 ms time resolution. Such acquisition is here called the Fast Acquisition Speed Technique (FAST). The analytical capabilities of the FAST were evaluated on a sector field instrument with high ion transmission efficiency (ITE). An algorithm for distinguishing particle events from dissolved and/or background signals was developed, and it was possible to detect 6.4 nm AuNPs that delivered only 2 ions to the detector. The influence of dwell time was investigated and it was concluded that the minimum DLs is achieved for dwell times close to the duration of particle events similar to 0.2 ms. Attempts to further improve the DLs should therefore be focused on increasing the ITE of the mass spectrometer.
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45.
  •  
46.
  • Tuoriniemi, Jani, 1982, et al. (författare)
  • Improving the accuracy of single particle ICPMS for measurement of size distributions and number concentrations of nanoparticles by determining analyte partitioning during nebulisation
  • 2014
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 29:4, s. 743-752
  • Tidskriftsartikel (refereegranskat)abstract
    • Application of single particle ICP-MS (spICPMS) for measurement of the size and number concentration, c(p), of nanoparticles is currently hampered by insufficient accuracy. The relative contributions of different types of noise to the overall uncertainty during spICPMS measurements of Ag and Au nanoparticle dispersions were quantified showing that the accuracy of spICPMS is mainly limited by the uncertainty in nebulization efficiency (f(neb)). This uncertainty was improved by correcting f(neb) for analyte partitioning effects during nebulization, and the calculated Ag and Au nanoparticle sizes were in close agreement with sizes determined by scanning electron microscopy. The duration of the particle events was measured, which allowed correction for incomplete particle events and detector dead time, and determination of the effective dwell time for particle counting. The c(p) measured with spICPMS agreed with that measured by counting particles deposited on filters, and calculated from the mass concentration of the analyte.
  •  
47.
  • Tuoriniemi, Jani, et al. (författare)
  • Measurement of number concentrations and sizes of Au nano-particles spiked into soil by laser ablation single particle ICPMS
  • 2020
  • Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 35, s. 1678-1686
  • Tidskriftsartikel (refereegranskat)abstract
    • A novel method to directly quantify nanoparticles (NPs) in a soil matrix by laser ablation single particle inductively coupled plasma mass spectrometry (LA-sp-ICPMS) was developed. Different concentrations of 60, 100, or 250 nm diameter gold NPs (AuNP) were deposited directly on polyether sulfone (PES) ultrafiltration membranes or immersed in soil. The ICPMS sensitivity was calibrated using aqueous dissolved Au standards and an aqueous AuNP size standard dispersion was used to calculate the transmission efficiency. In the case of the soil samples, sizing proved to be more accurate when calibration occurred while ablating a non-spiked soil. A linear relation was found between the spiked AuNP number concentrations and the particle event frequencies measured in the ablated area. Particle recovery on PES filters ranged only between 29 to 42% and recovery of soil-spiked AuNP on thin tape was between 15 and 60% and increased with size. However, 70-85% mass recovery in the ablated area was obtained when the soil sample was deposited on a thicker, opaque double sided tape suggesting that the substrate material is instrumental in absorbing excess laser energy thus enhancing recovery. The rate of soil ablation and mass transfer into the plasma was quantified to calculate the recovery using the same soils spiked with indium. The presented method thus has significant potential to be used for routine quantification of the particle size distributions of engineered or natural NPs in soil and possibly other powder samples with significantly fewer artifacts than extraction followed by aqueous analysis.
  •  
48.
  • Tuoriniemi, Jani, 1982, et al. (författare)
  • Size dependence of silver nanoparticle removal in a wastewater treatment plant mesocosm measured by FAST single particle ICP-MS
  • 2017
  • Ingår i: Environmental Science-Nano. - : Royal Society of Chemistry (RSC). - 2051-8153 .- 2051-8161. ; 4:5, s. 1189-1197
  • Tidskriftsartikel (refereegranskat)abstract
    • The quantities of engineered nanoparticles (NP) released to the environment are often influenced by their fate in waste water treatment plants (WWTP). Here, 40 nm silver NP (AgNP) were spiked into a mesocosm simulating the process used at a major municipal WWTP. The evolution of the mass distributions and number concentrations were followed by fast acquisition speed technique single particle inductively coupled mass spectrometry (FAST spICP-MS) using a high-resolution ICP-MS. It was thus possible to detect smaller Ag containing NP than hitherto possible in similar studies. These small particles (ca. 5-10 nm in corresponding metallic Ag equivalent spherical diameter) were possibly dissolved Ag+ precipitated as Ag2S particles. They were detected immediately upon spiking and were stable with respect to aggregation and thus much less removed by the WWTP process compared to the 40 nm AgNP. The results also suggested that any transformation of the latter AgNP occurred without dissolution. Most of these larger AgNP were probably removed by aggregation with large floc particles and subsequent sedimentation with the suspended particulate matter in the simulated WWTP process. The results have implications for differentiating the fate of nanoparticles as a function of size and demonstrate how spICP-MS can reveal such size-dependent fate dynamics.
  •  
49.
  •  
50.
  • Van Caneghem, J., et al. (författare)
  • Immobilization of antimony in waste-to-energy bottom ash by addition of calcium and iron containing additives
  • 2016
  • Ingår i: Waste Management. - : Elsevier BV. - 0956-053X. ; 54, s. 162-168
  • Tidskriftsartikel (refereegranskat)abstract
    • The leaching of Sb from waste-to-energy (WtE) bottom ash (BA) often exceeds the Dutch limit value of 0.32 mg kg(-1) for recycling of BA in open construction applications. From the immobilization mechanisms described in the literature, it could be concluded that both Ca and Fe play an important role in the immobilization of Sb in WtE BA. Therefore, Ca and Fe containing compounds were added to the samples of the sand fraction of WtE BA, which in contrast to the granulate fraction is not recyclable to date, and the effect on the Sb leaching was studied by means of batch leaching tests. Results showed that addition of 0.5 and 2.5% CaO, 5% CaCl2, 2.5% Fe-2(SO4)(3) and 1% FeCl3 decreased the Sb leaching from 0.62 +/- 0.02 mg kg(DM)(-1) to 0.20 +/- 0.02, 0.083 +/- 0.044, 0.25 +/- 0.01, 0.27 +/- 0.002 and 0.29 +/- 0.02 mg kg(DM)(-1), respectively. Due to the increase in pH from 11.41 to 12.53 when 2.5% CaO was added, Pb and Zn leaching increased and exceeded the respective leaching limits. Addition of 5% CaCO3 had almost no effect on the Sb leaching, as evidenced by the resulting 0.53 mg kg(DM)(-1) leaching concentration. This paper shows a complementary enhancement of the effect of Ca and Fe, by comparing the aforementioned Sb leaching results with those of WtE BA with combined addition of 2.5% CaO or 5% CaCl2 with 2.5% Fe-2(SO4)(3) or 1% FeCl3. These lab scale results suggest that formation of romeites with a high Ca content and formation of iron antimonate (tripuhyite) with a very low solubility are the main immobilization mechanisms of Sb in WtE BA. Besides the pure compounds and their mixtures, also addition of 10% of two Ca and Fe containing residues of the steel industry, hereafter referred to as R1 and R2, was effective in decreasing the Sb leaching from WtE BA below the Dutch limit value for reuse in open construction applications. To evaluate the long term effect of the additives, pilot plots of WtE BA with 10% of R1 and 5% and 10% of R2 were built and samples were submitted to leaching tests at regular intervals over time. The Sb leaching from untreated WtE BA was just below or above the Dutch limit value. The Sb leaching from the pilot plots of BA with additives first remained stable around 0.13 mg kg(-1) but had a tendency to slightly increase after 6 months, indicating the need for further research on the effect of weathering, and more specifically of carbonation, on Sb leaching from WtE BA.
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