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2025
Carbonaceous aerosols (CA), composed of black carbon (BC) and organic matter (OM), significantly impact the climate. Light absorption properties of CA, particularly of BC and brown carbon (BrC), are crucial due to their contribution to global and regional warming. We present the absorption properties of BC (bAbs,BC) and BrC (bAbs,BrC) inferred using Aethalometer data from 44 European sites covering different environments (traffic (TR), urban (UB), suburban (SUB), regional background (RB) and mountain (M)). Absorption coefficients showed a clear relationship with station setting decreasing as follows: TR > UB > SUB > RB > M, with exceptions. The contribution of bAbs,BrC to total absorption (bAbs), i.e. %AbsBrC, was lower at traffic sites (11–20 %), exceeding 30 % at some SUB and RB sites. Low AAE values were observed at TR sites, due to the dominance of internal combustion emissions, and at some remote RB/M sites, likely due to the lack of proximity to BrC sources, insufficient secondary processes generating BrC or the effect of photobleaching during transport. Higher bAbs and AAE were observed in Central/Eastern Europe compared to Western/Northern Europe, due to higher coal and biomass burning emissions in the east. Seasonal analysis showed increased bAbs, bAbs,BC, bAbs,BrC in winter, with stronger %AbsBrC, leading to higher AAE. Diel cycles of bAbs,BC peaked during morning and evening rush hours, whereas bAbs,BrC, %AbsBrC, AAE, and AAEBrC peaked at night when emissions from household activities accumulated. Decade-long trends analyses demonstrated a decrease in bAbs, due to reduction of BC emissions, while bAbs,BrC and AAE increased, suggesting a shift in CA composition, with a relative increase in BrC over BC. This study provides a unique dataset to assess the BrC effects on climate and confirms that BrC can contribute significantly to UV–VIS radiation presenting highly variable absorption properties in Europe.
Elsevier
2025
2025
Recent methane surges reveal heightened emissions from tropical inundated areas
Record breaking atmospheric methane growth rates were observed in 2020
and 2021 (15.2±0.5 and 17.8±0.5 parts per billion per year), the highest since the
early 1980s. Here we use an ensemble of atmospheric inversions informed by
surface or satellite methane observations to infer emission changes during
these two years relative to 2019. Results show global methane emissions
increased by 20.3±9.9 and 24.8±3.1 teragrams per year in 2020 and 2021,
dominated by heightened emissions from tropical and boreal inundated areas,
aligning with rising groundwater storage and regional warming. Current
process-based wetland models fail to capture the tropical emission surges
revealed by atmospheric inversions, likely due to inaccurate representation of
wetland extents and associated methane emissions. Our findings underscore
the critical role of tropical inundated areas in the recent methane emission
surges and highlight the need to integrate multiple data streams and modeling
tools for better constraining tropical wetland emissions.
Springer Nature
2024
In the framework of the Forum for Air Quality Modelling in Europe (FAIRMODE), a modelling intercomparison exercise for computing NO2 long-term average concentrations in urban districts with a very high spatial resolution was carried out. This exercise was undertaken for a district of Antwerp (Belgium). Air quality data includes data recorded in air quality monitoring stations and 73 passive samplers deployed during one-month period in 2016. The modelling domain was 800 × 800 m2. Nine modelling teams participated in this exercise providing results from fifteen different modelling applications based on different kinds of model approaches (CFD – Computational Fluid Dynamics-, Lagrangian, Gaussian, and Artificial Intelligence). Some approaches consisted of models running the complete one-month period on an hourly basis, but most others used a scenario approach, which relies on simulations of scenarios representative of wind conditions combined with post-processing to retrieve a one-month average of NO2 concentrations.
The objective of this study is to evaluate what type of modelling system is better suited to get a good estimate of long-term averages in complex urban districts. This is very important for air quality assessment under the European ambient air quality directives. The time evolution of NO2 hourly concentrations during a day of relative high pollution was rather well estimated by all models. Relative to high resolution spatial distribution of one-month NO2 averaged concentrations, Gaussian models were not able to give detailed information, unless they include building data and street-canyon parameterizations. The models that account for complex urban geometries (i.e. CFD, Lagrangian, and AI models) appear to provide better estimates of the spatial distribution of one-month NO2 averages concentrations in the urban canopy. Approaches based on steady CFD-RANS (Reynolds Averaged Navier Stokes) model simulations of meteorological scenarios seem to provide good results with similar quality to those obtained with an unsteady one-month period CFD-RANS simulations.
Elsevier
2024
Background
Hazard and risk assessment of nanomaterials (NMs) face challenges due to, among others, the numerous existing nanoforms, discordant data and conflicting results found in the literature, and specific challenges in the application of strategies such as grouping and read-across, emphasizing the need for New Approach Methodologies (NAMs) to support Next Generation Risk Assessment (NGRA). Here these challenges are addressed in a study that couples physico-chemical characterization with in vitro investigations and in silico similarity analyses for nine nanoforms, having different chemical composition, sizes, aggregation states and shapes. For cytotoxicity assessment, three methods (Alamar Blue, Colony Forming Efficiency, and Electric Cell-Substrate Impedance Sensing) are applied in a cross-validation approach to support NAMs implementation into NGRA.
Results
The results highlight the role of physico-chemical properties in eliciting biological responses. Uptake studies reveal distinct cellular morphological changes. The cytotoxicity assessment shows varying responses among NMs, consistent among the three methods used, while only one nanoform gave a positive response in the genotoxicity assessment performed by comet assay.
Conclusions
The study highlights the potential of in silico models to effectively identify biologically active nanoforms based on their physico-chemical properties, reinforcing previous knowledge on the relevance of certain properties, such as aspect ratio. The potential of implementing in vitro methods into NGRA is underlined, cross-validating three cytotoxicity assessment methods, and showcasing their strength in terms of sensitivity and suitability for the testing of NMs.
BioMed Central (BMC)
2024
New advanced models (NAMs) for risk assessment of bisphenol A alternatives
The safety of bisphenol A (BPA) due to its adverse effects on the immune system has led to an increasing concern and a significant regulatory shift. The European Food Safety Authority (EFSA) proposed a reduction in the tolerable daily intake (TDI) of BPA in food in their 2023 scientific opinion, highlighting the need for stricter regulations compared to their previous assessment in 2015. This regulatory action has spurred the production of BPA alternatives, raising concerns about their safety due to insufficient toxicological data. Addressing this gap is crucial for ensuring human and environmental health. In this project, multiple genotoxicity endpoints were applied for testing of two regulatory relevant BPA alternatives, bisphenol E (BPE) and bisphenol P (BPP), in different human models: 2D HepG2 liver cells, 3D liver spheroids and primary human peripheral blood lymphocytes. DNA strand breaks and oxidised base lesions were evaluated by the enzyme-modified version of the comet assay, while clastogenicity and aneugenicity were analysed by the in vitro micronucleus assay (OECD TG 487, 2016), together with cytotoxicity. Development of new advanced models (NAMs), as 3D spheroids, are essential for next-generation risk assessment (NGRA) in line with the 3R's to replace, reduce or refine animal experiments. In this aspect, validation and standardisation of NAMs are needed to reach regulatory readiness level and development of OECD Test Guidelines. Therefore, a standardisation and pre-validation of the advanced 3D liver spheroid model was performed by using multiple genotoxicity endpoints and by comparing the obtained results with standard genotoxicity models.
2024
We investigate the concentration fluctuations of passive scalar plumes emitted from small, localised (point-like) steady sources in a neutrally stratified turbulent boundary layer over a rough wall. The study utilises high-resolution large-eddy simulations for sources of varying sizes and heights. The numerical results, which show good agreement with wind-tunnel studies, are used to estimate statistical indicators of the concentration field, including spectra and moments up to the fourth order. These allow us to elucidate the mechanisms responsible for the production, transport and dissipation of concentration fluctuations, with a focus on the very near field, where the skewness is found to have negative values – an aspect not previously highlighted. The gamma probability density function is confirmed to be a robust model for the one-point concentration at sufficiently large distances from the source. However, for ground-level releases in a well-defined area around the plume centreline, the Gaussian distribution is found to be a better statistical model. As recently demonstrated by laboratory results, for elevated releases, the peak and shape of the pre-multiplied scalar spectra are confirmed to be independent of the crosswind location for a given downwind distance. Using a stochastic model and theoretical arguments, we demonstrate that this is due to the concentration spectra being directly shaped by the transverse and vertical velocity components governing the meandering of the plume. Finally, we investigate the intermittency factor, i.e. the probability of non-zero concentration, and analyse its variability depending on the thresholds adopted for its definition.
Cambridge University Press
2024
Geopolitical events have shown to threaten European energy security in 2022. In Norway, accustomed to low energy prices, the southern part saw 4 times higher electricity prices in 2022 than long term average, whereas in the north, energy prices remained stable. This offers an opportunity to examine the effect of price on household energy consumption and PM2.5 emissions from the residential sector. In the south, electricity consumption went down by 10% while in the north it remained unchanged relative to expected values. While the documented correlation between increased electricity prices and reduced consumption is well-established, our study uniquely captures a substantial shift towards wood as an alternative energy source. In the south, wood for heating increased by approximately 40%, effectively replacing half of the electricity saved. This increase happened despite prices being curbed by strong government subsidies on electricity. Faced with higher energy costs in Europe, we simulate a scenario where consumers across Europe look for affordable energy. With gas and electricity prices predicted to remain well above long-term averages until 2030, biomass will be an attractive option. Our study shows how a shift can endanger Europe's Zero-Pollution strategy, and the need for initiatives targeting the reduction of residential biomass heating.
Elsevier
2024
2024