| 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.
|
|
| 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.
|
|
| 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.
|
|
| 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.
|
|
| 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.
|
|
| 6. |
|
|
| 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
|
|
| 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.
|
|
| 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.
|
|
| 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.
|
|
