Background, aim and scope
In 2005, a comprehensive comparison of life cycle impact assessment toxicity characterisation models was initiated by the United Nations Environment Program (UNEP)–Society ...for Environmental Toxicology and Chemistry (SETAC) Life Cycle Initiative, directly involving the model developers of CalTOX, IMPACT 2002, USES-LCA, BETR, EDIP, WATSON and EcoSense. In this paper, we describe this model comparison process and its results—in particular the scientific consensus model developed by the model developers. The main objectives of this effort were (1) to identify specific sources of differences between the models’ results and structure, (2) to detect the indispensable model components and (3) to build a scientific consensus model from them, representing recommended practice.
Materials and methods
A chemical test set of 45 organics covering a wide range of property combinations was selected for this purpose. All models used this set. In three workshops, the model comparison participants identified key fate, exposure and effect issues via comparison of the final characterisation factors and selected intermediate outputs for fate, human exposure and toxic effects for the test set applied to all models.
Results
Through this process, we were able to reduce inter-model variation from an initial range of up to 13 orders of magnitude down to no more than two orders of magnitude for any substance. This led to the development of USEtox, a scientific consensus model that contains only the most influential model elements. These were, for example, process formulations accounting for intermittent rain, defining a closed or open system environment or nesting an urban box in a continental box.
Discussion
The precision of the new characterisation factors (CFs) is within a factor of 100–1,000 for human health and 10–100 for freshwater ecotoxicity of all other models compared to 12 orders of magnitude variation between the CFs of each model, respectively. The achieved reduction of inter-model variability by up to 11 orders of magnitude is a significant improvement.
Conclusions
USEtox provides a parsimonious and transparent tool for human health and ecosystem CF estimates. Based on a referenced database, it has now been used to calculate CFs for several thousand substances and forms the basis of the recommendations from UNEP-SETAC’s Life Cycle Initiative regarding characterisation of toxic impacts in life cycle assessment.
Recommendations and perspectives
We provide both recommended and interim (not recommended and to be used with caution) characterisation factors for human health and freshwater ecotoxicity impacts. After a process of consensus building among stakeholders on a broad scale as well as several improvements regarding a wider and easier applicability of the model, USEtox will become available to practitioners for the calculation of further CFs.
Perchlorate has been categorised as a potential contaminant and researched for years, but there are still many unknowns regarding this anion's contamination impacts. In this review, the basic ...information about perchlorate is summarised and evaluated, including the physical-chemical properties, fate and transportation, toxicity, analysis, and remediation. Especially, recent advances on analysis and remediation are emphasised and evaluated, such as in-situ imaging analysis and on-site bio-remediation respectively. The high solubility and persistence of the perchlorate anion mean its contamination is different from others, particularly in terms of analysis and remediation that might lead to secondary contamination. The knowledge gaps are listed for future research.
Display omitted
•Perchlorate is reviewed towards analysis and remediation.•Recent advances on the analysis and remediation are emphasised.•Imaging and in-situ analysis is recommended.•Knowledge gaps are listed for future research.
•Determination of solar and visible properties of glazed units with PCM.•Spectral and angular dependent measurements with advanced experimental facility.•Characterisation of different PCM thicknesses ...and aggregation states.
Phase change materials (PCMs) have been proposed as a means to increase the thermal inertia of glazing systems. These materials have optical features that need to be investigated and characterised in order to better understand the potential of these systems and to provide reliable data for numerical simulations.
The spectral and angular behaviour of different PCM glazing samples, characterised by different thicknesses of PCMs, were investigated by means of commercial spectrophotometer and by means of a dedicated optical test bed that includes a large integrating sphere with a diameter of 0.75m. Such equipment was necessary because of the highly diffusive behaviour of the PCM layer when in the solid state of aggregation.
The paper provides a data set of luminous and solar properties of glazing units with PCMs in gaps; the data set uses results from an advanced optical facility that overcomes the intrinsic limitations of commercial spectrophotometers in measuring the optical properties of the advanced transparent materials. In detail, transmittance, reflectance and absorptance spectra of double glazing units characterised by different PCM layer thicknesses in the gap, measured at different incident beam angles, are reported. Integrated values calculated according to relevant international standards are thus provided. Optical features of PCM glazing systems are also highlighted and issues related to the integration of these systems in buildings are discussed.
•Temporal characterisation of wave and tidal resource availability for Great Britain.•Ten metrics used to explore temporal characterisation and supply-demand matching.•Generation profiles with marine ...energy consistently outperform those without.•Correlation with load is not a suitable metric to establish supply-demand alignment.•Detailed discussion of potential GB power system benefits from marine energy.
Wave and tidal energy have the potential to provide benefits to power systems with high proportions of stochastic renewable generation. This is particularly applicable in combination with wind and solar photovoltaics, as the offsetting of these renewable resources results in more reliable renewable generation. This study utilises ten metrics to quantify the temporal complementarity and supply-demand balancing requirements of the energy mix in Great Britain, to investigate the potential magnitude of these system benefits. Wave and tidal generation profiles are created using historical resource data and hydrodynamic models. The results show that the inclusion of wave and tidal generation creates a renewable energy mix which is more available under multiple conditions: throughout a year of operation; at times of peak demand; for multiple consecutive hourly time periods; and at times when wind and solar generation are not available. Three regional case studies also show that the inclusion of marine energy allows for improved regional supply-demand matching, reducing instances of energy shortage and excess and potentially relieving transmission congestion at particularly constrained locations within GB. Finally, the implications of these findings are discussed in terms of GB wholesale market operation, system balancing and system security.
•New methods for flotation agents combine microbiology and flotation theory.•Optimization and characterization of EPS produced by Azotobacter vinelandii.•Culture medium compositions affect the ...structure and composition of EPS.•Synthesized EPS for selective separation in chalcopyrite-chlorite flotation.
In this study, we investigated microbial flotation as a green separation technology in mineral processing. We explored their potential use as environmentally friendly depressants for chlorite by extracting and purifying exopolysaccharides (EPS) from Azotobacter vinelandii (A.v) and comparing them with commercial alginate. Results showed that EPS derived from A.v under different fermentation substrates, particularly carbon sources, exhibited diverse structures, compositions and surface morphologies. Importantly, only some of these EPS’ variants demonstrated effective inhibition of chlorite. Scanning electron microscope (SEM) analysis revealed that the EPS with effective chlorite inhibition displayed a rough and porous surface morphology, resembling spherical-like structural units. We further investigated the different compositions of EPS using colorimetric methods, identifying total carbohydrates, uronic acids, acetyl and pyruvyl groups and proteins. In addition, we observed that functional groups, including acetyl group (CH3CO) and pyruvic acid (COCOOH), were detected in certain EPS variants, and these functional groups may be associated with the observed inhibition effect on chlorite. These findings highlight the potential of EPS derived from Azotobacter vinelandii as an environmentally friendly depressant for chlorite.
Bulk titanium and CoCr are the most common metals for use in orthopedic implants, but there are significant advantages in alternative substrates. Research in the last decade has focused on various ...alternatives; however, these materials are hindered by the adhesion of hydroxyapatite layers to non-bulk metal parts. Demonstrated in this work is the ability to grow hydroxyapatite on surfaces other than bulk metallic parts through the process and characterisation of coating properties. In this study, hydroxyapatite (HA) is grown from saturated solution onto thin titanium films and silicon substrates. Its efficacy is shown to be dependent on substrate roughness. The mechanism of the hydroxyapatite growth is investigated in terms of initial attachment and morphological development using SEM analysis. Characterisation of hydroxyapatite layers by XRD demonstrates how the hydroxyapatite forms from amorphous phases to preferential crystal growth along the 002 direction and TEM imagery confirms specific d-spacings. SEM-EDX and FTIR show adherence to known HA phases through elemental atomic weight percentages and bond assignment. All data are collated and reviewed through the lens of different substrates. The results suggest that once hydroxyapatite seeds, it grows identically regardless of substrate.
Display omitted
•Sulphided CoMo/γ-Al2O3 catalysts were prepared based on orthogonal design.•Near 100% efficiency was achieved for the removal of SO2 from flue gas.•SO2 is completely converted into ...elemental S by the Al-S400-0.31 catalyst.•Mechanism for selective catalytic reduction of SO2 to elemental S was proposed.
This study aimed to develop sulphided CoMo/γ-Al2O3 catalysts to recover elemental sulphur via selective reduction and to understand the catalytic mechanism of the selective catalytic reduction (SCR) of SO2 into sulphur when CO is used as the reducing agent. A series of catalysts were prepared based on Taguchi’s L9 orthogonal array and were evaluated in terms of their SO2 conversion efficiency, selectivity of SO2 reduction to elemental sulphur, elemental sulphur yield, and selectivity of COS formation. It is found that the catalyst sulphided at 400°C with a ratio of Co/(Co+Mo)=0.31 and supported on γ-Al2O3 had the best performance among all the catalysts studied. In addition, the physical–chemical properties and catalytic activities of this catalyst were studied systematically. The mechanism of selective reduction of SO2 to elemental sulphur using CO as the reducing agent was therefore proposed.
Sporotrichosis is caused by species of the genus Sporothrix. From 1998 to 2015, 4,703 cats were diagnosed at the Fundação Oswaldo Cruz (Fiocruz), Rio de Janeiro, Brazil. Even after the description of ...the Sporothrix species, the characterisation of feline isolates is not performed routinely.
To characterise the clinical isolates from cats at the species level and correlate them with the clinical and epidemiological characteristics of the cats.
Forty seven Sporothrix spp. isolates from cats assisted at Fiocruz from 2010 to 2011 were included. Medical records were consulted to obtain the clinical and epidemiological data. The isolates were identified through their morphological and physiological characteristics. T3B polymerase chain reaction (PCR) fingerprinting was used for molecular identification of the species.
In phenotypic tests, 34 isolates were characterised as S. brasiliensis, one as S. schenckii and 12 as Sporothrix spp. PCR identified all isolates as S. brasiliensis.
S. brasiliensis is the only etiological agent of feline sporotrichosis in Rio de Janeiro to date. None association was found between the isolates and the clinical and epidemiological data. In addition, we strongly recommend the use of molecular techniques for the identification of isolates of Sporothrix spp.
PDF
