Fant 10084 publikasjoner. Viser side 327 av 404:
2020
2020
The quality and relevance of nanosafety studies constitute major challenges to ensure their key role as a supporting tool in sustainable innovation, and subsequent competitive economic advantage. However, the number of apparently contradictory and inconclusive research results has increased in the past few years, indicating the need to introduce harmonized protocols and good practices in the nanosafety research community. Therefore, we aimed to evaluate if best-practice training and inter-laboratory comparison (ILC) of performance of the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay for the cytotoxicity assessment of nanomaterials among 15 European laboratories can improve quality in nanosafety testing. We used two well-described model nanoparticles, 40-nm carboxylated polystyrene (PS-COOH) and 50-nm amino-modified polystyrene (PS-NH2). We followed a tiered approach using well-developed standard operating procedures (SOPs) and sharing the same cells, serum and nanoparticles. We started with determination of the cell growth rate (tier 1), followed by a method transfer phase, in which all laboratories performed the first ILC on the MTS assay (tier 2). Based on the outcome of tier 2 and a survey of laboratory practices, specific training was organized, and the MTS assay SOP was refined. This led to largely improved intra- and inter-laboratory reproducibility in tier 3. In addition, we confirmed that PS-COOH and PS-NH2 are suitable negative and positive control nanoparticles, respectively, to evaluate impact of nanomaterials on cell viability using the MTS assay. Overall, we have demonstrated that the tiered process followed here, with the use of SOPs and representative control nanomaterials, is necessary and makes it possible to achieve good inter-laboratory reproducibility, and therefore high-quality nanotoxicological data.
2020
2020
The fingerprint of the summer 2018 drought in Europe on ground-based atmospheric CO2 measurements
During the summer of 2018, a widespread drought developed over Northern and Central Europe. The increase in temperature and the reduction of soil moisture have influenced carbon dioxide (CO2) exchange between the atmosphere and terrestrial ecosystems in various ways, such as a reduction of photosynthesis, changes in ecosystem respiration, or allowing more frequent fires. In this study, we characterize the resulting perturbation of the atmospheric CO2 seasonal cycles. 2018 has a good coverage of European regions affected by drought, allowing the investigation of how ecosystem flux anomalies impacted spatial CO2 gradients between stations. This density of stations is unprecedented compared to previous drought events in 2003 and 2015, particularly thanks to the deployment of the Integrated Carbon Observation System (ICOS) network of atmospheric greenhouse gas monitoring stations in recent years. Seasonal CO2 cycles from 48 European stations were available for 2017 and 2018. Earlier data were retrieved for comparison from international databases or national networks. Here, we show that the usual summer minimum in CO2 due to the surface carbon uptake was reduced by 1.4 ppm in 2018 for the 10 stations located in the area most affected by the temperature anomaly, mostly in Northern Europe. Notwithstanding, the CO2 transition phases before and after July were slower in 2018 compared to 2017, suggesting an extension of the growing season, with either continued CO2 uptake by photosynthesis and/or a reduction in respiration driven by the depletion of substrate for respiration inherited from the previous months due to the drought. For stations with sufficiently long time series, the CO2 anomaly observed in 2018 was compared to previous European droughts in 2003 and 2015. Considering the areas most affected by the temperature anomalies, we found a higher CO2 anomaly in 2003 (+3 ppm averaged over 4 sites), and a smaller anomaly in 2015 (+1 ppm averaged over 11 sites) compared to 2018.
This article is part of the theme issue ‘Impacts of the 2018 severe drought and heatwave in Europe: from site to continental scale'.
2020
2020
2021
The Community Inversion Framework v1.0: a unified system for atmospheric inversion studies
Atmospheric inversion approaches are expected to play a critical role in future observation-based monitoring systems for surface fluxes of greenhouse gases (GHGs), pollutants and other trace gases. In the past decade, the research community has developed various inversion software, mainly using variational or ensemble Bayesian optimization methods, with various assumptions on uncertainty structures and prior information and with various atmospheric chemistry–transport models. Each of them can assimilate some or all of the available observation streams for its domain area of interest: flask samples, in situ measurements or satellite observations. Although referenced in peer-reviewed publications and usually accessible across the research community, most systems are not at the level of transparency, flexibility and accessibility needed to provide the scientific community and policy makers with a comprehensive and robust view of the uncertainties associated with the inverse estimation of GHG and reactive species fluxes. Furthermore, their development, usually carried out by individual research institutes, may in the future not keep pace with the increasing scientific needs and technical possibilities. We present here the Community Inversion Framework (CIF) to help rationalize development efforts and leverage the strengths of individual inversion systems into a comprehensive framework. The CIF is primarily a programming protocol to allow various inversion bricks to be exchanged among researchers. In practice, the ensemble of bricks makes a flexible, transparent and open-source Python-based tool to estimate the fluxes of various GHGs and reactive species both at the global and regional scales. It will allow for running different atmospheric transport models, different observation streams and different data assimilation approaches. This adaptability will allow for a comprehensive assessment of uncertainty in a fully consistent framework. We present here the main structure and functionalities of the system, and we demonstrate how it operates in a simple academic case.
2021
The effective enrichment of perfluoroalkyl acids (PFAAs) in sea spray aerosols (SSA) demonstrated in previous laboratory studies suggests that SSA is a potential source of PFAAs to the atmosphere. In order to investigate the influence of SSA on atmospheric PFAAs in the field, 48 h aerosol samples were collected regularly between 2018 and 2020 at two Norwegian coastal locations, Andøya and Birkenes. Significant correlations (p < 0.05) between the SSA tracer ion, Na+, and PFAA concentrations were observed in the samples from both locations, with Pearson’s correlation coefficients (r) between 0.4–0.8. Such significant correlations indicate SSA to be an important source of atmospheric PFAAs to coastal areas. The correlations in the samples from Andøya were observed for more PFAA species and were generally stronger than in the samples from Birkenes, which is located further away from the coast and closer to urban areas than Andøya. Factors such as the origin of the SSA, the distance of the sampling site to open water, and the presence of other PFAA sources (e.g., volatile precursor compounds) can have influence on the contribution of SSA to PFAA in air at the sampling sites and therefore affect the observed correlations between PFAAs and Na+.
2021
Global predictions of primary soil salinization under changing climate in the 21st century
Soil salinization has become one of the major environmental and socioeconomic issues globally and this is expected to be exacerbated further with projected climatic change. Determining how climate change influences the dynamics of naturally-occurring soil salinization has scarcely been addressed due to highly complex processes influencing salinization. This paper sets out to address this long-standing challenge by developing data-driven models capable of predicting primary (naturally-occurring) soil salinity and its variations in the world’s drylands up to the year 2100 under changing climate. Analysis of the future predictions made here identifies the dryland areas of South America, southern and western Australia, Mexico, southwest United States, and South Africa as the salinization hotspots. Conversely, we project a decrease in the soil salinity of the drylands in the northwest United States, the Horn of Africa, Eastern Europe, Turkmenistan, and west Kazakhstan in response to climate change over the same period.
2021
Fluorescent Nanocomposites: Hollow Silica Microspheres with Embedded Carbon Dots
Intrinsically fluorescent carbon dots may form the basis for a safer and more accurate sensor technology for digital counting in bioanalytical assays. This work presents a simple and inexpensive synthesis method for producing fluorescent carbon dots embedded in hollow silica particles. Hydrothermal treatment at low temperature (160 °C) of microporous silica particles in presence of urea and citric acid results in fluorescent, microporous and hollow nanocomposites with a surface area of 12 m2/g. High absolute zeta potential (−44 mV) at neutral pH demonstrates the high electrosteric stability of the nanocomposites in aqueous solution. Their fluorescence emission at 445 nm is remarkably stable in aqueous dispersion under a wide pH range (3–12) and in the dried state. The biocompatibility of the composite particles is excellent, as the particles were found to show low genotoxicity at exposures up to 10 μg/cm2.
2021
2021
2021
An update on low-cost sensors for the measurement of atmospheric composition
The report reflects on the state of the art in terms of accuracy, reliability and reproducibility of different sensors used for the measurements of reactive and greenhouse gases, and aerosols, along with the key analytical principles and what has been learned so far about low-cost sensors from both laboratory studies and real-world tests (up to August 2020). In some cases, scientific literature that had been accepted, but not yet published in a final form, was included in this review. Some national and international government documents were also included in this synthesis. The report includes eight distinct sections, including an Introduction to the Report, Main Principles and Components, Evaluation Activities, Sensor Performance, Communicating LCS to Society, and Expert Consensus and Advice. Communicating LCS to Society is a new section to the original 2018 report and includes a consensus viewpoint on strategies for communicating LCS data and technologies more broadly to the lay public. This report also includes a set of specific expert consensus recommendations for LCS users across different user groups.
WMO
2021
The increase of the commercial availability of low-cost sensor technology to monitor atmospheric composition is contributing to the rapid adoption of such technology by both public authorities and self-organized initiatives (e.g. grass root movements, citizen science, etc.). Low-cost sensors (LCS) can provide real time measurements, in principle at lower cost than traditional monitoring reference stations, allowing higher spatial coverage than the current reference methods. However, data quality from LCS is lower than the one provided by reference methods. Also, the total cost of deploying a dense sensor network needs to consider the costs associated not only to the sensor platforms but also the costs associated for instance with deployment, maintenance and data transmission.
This report aims to give an overview of the current status of LCS technology in relation to commercialization, measuring capabilities and data quality, with especial emphasis on the challenges associated to the use of this novel technology, and the opportunities they open when correctly used.
NILU
2021
Kunnskapsstatus for tverrfaglig klima- og miljøforskning
På oppdrag fra Klima- og miljødepartementet har vi i dette arbeidet svart ut en rekke spørsmål om tverrfaglig klima- og miljøforskning, samt noen spørsmål om transfaglig forskning. Vi har samlet inn data gjennom flere litteratursøk, intervjuer, én spørreundersøkelse, workshop mm. Alle litteratursøk dekker klima og miljøpublikasjoner uavhengig av hvor forskningen er gjort. Alle andre funn fra forskningsmiljøene er avgrenset til grunnforskning og anvendt forskning ved universitetene og forskningsinstitutt som mottar grunnfinansiering. Bruk av klima- og miljøforskning i forvaltningen og involvering av forvaltningen er avgrenset til statlig forvaltning. Det er usikkerhet i våre funn, men funnene vurderes likevel som tilstrekkelig robuste til å svare ut spørsmålene. Vi finner at bruken av begrepet tverrfaglig er mangfoldig. Et bredt antall fag og institusjoner er involvert i slik forskning og det samarbeides mest på tvers av naturvitenskap og samfunnsvitenskap. Vi har funnet at andelen klima- og miljøpublikasjoner som er tverrfaglig på tvers av minst to av naturvitenskap, samfunnsvitenskap, humaniora og rettsvitenskap, er 24 prosent. I Norge oppleves behovet for tverrfaglig klima- og miljøforskning som økende. Den viktigste driveren for økningen er samfunnsbehovene. Det forskes også mer tverrfaglig. Et globalt litteratursøk antyder imidlertid at antall tverrfaglige klima- og miljøpublikasjoner og totalt antall klima- og miljøpublikasjoner øker med omtrent samme takt slik at andelen av publikasjoner som er tverrfaglige, endres i liten grad. Monofaglig praksis er vanligere enn flerfaglig. Flerfaglighet er vanligere enn tverrfaglighet. Det oppleves å være betydelige barrierer for tverrfaglig klima- og miljøforskning. Faglige barrierer og manglende merittering for tverrfaglig forskning løftes spesielt fram, men også andre barrierer er betydelige. Det er relativt liten forskjell i opplevelse av barrierer for forskere ved universitetene og forskningsinstitutter. For transfaglig forskning peker både forvaltning og forskere på mangel på tid som en sentral barriere. Forskning på tverrfaglig og transfaglig forskning øker.
CIENS
2021
2021