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α/δ bronze bells are heritage materials subject to corrosion. The alteration of a high-tin bronze bell casted in the 1930s and exposed to a marine environment in a steeple was studied. The ternary bronze (Cu-Sn-Pb) alloy displays inclusions and a porosity due to micro-shrinkages and poor gas evacuation. This altered bronze is characterized to (1) assess the influence of the manufacturing techniques and (2) hypothesize a micro-infiltration scenario of its alteration. After exposure to the atmosphere, a transformed superficial medium overlaying layers of atacamite-paratacamite-cassiterite appears. Under them, the corrosion of the α dendritic structure and α/δ eutectoid characteristic of bronze bell is evidenced. The α pitting has a pronounced multilayered structure of cassiterite and cuprite-copper chloride, whereas the δ corrosion is composed of cassiterite and traces of cuprite. To understand better the lead impact on corrosion process, samples of the alloy were exposed in the laboratory to a synthetic marine solution. The long-term corrosion behavior of the studied bell shows some similarities to those of other high tin bronze artefacts. The hypothesis of a corrosion scenario emphasizes the importance of the bells manufacturing techniques, α/δ structure of the ternary Cu-Sn-Pb alloy, and infiltrating networks of environmental fluids.

Potash lime silicate glasses were extensively used during the Middle Ages as components of stained glass windows. Their external faces have been subjected to alteration in the atmospheric medium for centuries, leading to the development of thick alteration layers on the surfaces. This alteration is mainly caused by water in liquid (rainfall) or gaseous (vapor) form. In order to implement geochemical models simulating the long-term behavior of these glasses by coupling the different atmospheric factors, it is necessary to study mechanisms and kinetics of alteration induced by these different hygroscopic situations (rainfall and relative humidity). The aim of this study is here to evaluate the impact of liquid water on stained glass windows and especially to determine alteration rate laws of dissolution and interdiffusion as a function of pH and temperature. For that, a medieval model glass was altered in aqueous solution in batch experiments at different pH values (from 2 to 11), temperatures (from 5 to 70 °C) and saturation states of the solution. From the elemental concentrations in solution, the release rate of elements was calculated and the pH- and T-dependencies were determined. The dissolution and interdiffusion rate laws can now be used to simulate the alteration of a medieval glass submitted to a rainfall event. Moreover, this study highlights that the Si-K-Ca medieval glass presents a very low pH-dependency at alkaline pH, which can be explained by its composition.

Determination of the glass alteration rate requires the knowledge of the reactive surface area that is a key parameter. Many studies have evaluated this parameter for glass monoliths or powders by using either geometrical or BET surface area, but few have focused on the impact of glass roughness on the reactive surface area and on the global alteration. The roughness can be expected to proportionally increase the reactive surface area and to modify local conditions of alteration. Therefore, the aim of this study is to evaluate the impact of surface roughness and asperities on the alteration of a model medieval-type glass. Experiments were performed in aqueous medium on samples with different initial surface roughness level. The results show that, for an initially smooth surface, the altered layer is continuous and tends to scale, whereas for an initially rough surface, the alteration is heterogeneous in morphology and composition and asperities are highly hollowed. Surprisingly, despite these differences, the quantity of altered glass is relatively similar, which shows that the roughness does not significantly increase the reactive surface area. This is explained by a fast solution saturation in asperities that minimizes their contribution to the global alteration.

International audience; Accurate knowledge of infrared emissivity is important in applications such as surface temperature measurements by infrared thermography or thermal balance for building walls. A comparison of total hemispherical emissivity measurement was performed by two laboratories: the Laboratoire National de Métrologie et d'Essais (LNE) and the Centre d'Études et de Recherche en Thermique, Environnement et Systèmes (CERTES). Both laboratories performed emissivity measurements on four samples, chosen to cover a large range of emissivity values and angular reflectance behaviors. The samples were polished aluminum (highly specular, low emissivity), bulk PVC (slightly specular, high emissivity), sandblasted aluminum (diffuse surface, medium emissivity), and aluminum paint (slightly specular surface, medium emissivity). Results obtained using five measurement techniques were compared. LNE used a calorimetric method for direct total hemispherical emissivity measurement [1], an absolute reflectometric measurement method [2], and a relative reflectometric measurement method. CERTES used two total hemispherical directional reflectometric measurement methods [3, 4]. For indirect techniques by reflectance measurements, the total hemispherical emissivity values were calculated from directional hemispherical reflectance measurement results using spectral integration when required and directional to hemispherical extrapolation. Results were compared, taking into account measurement uncertainties; an added uncertainty was introduced to account for heterogeneity over the surfaces of the samples and between samples. All techniques gave large relative uncertainties for a low emissive and very specular material (polished aluminum), and results were quite scattered. All the indirect techniques by reflectance measurement gave results within ±0.01 for a high emissivity material. A commercial aluminum paint appears to be a good candidate for producing samples with medium level of emissivity (about 0.4) and with good uniformity of emissivity values (within ±0.015).

International audience; As microplastic studies grow, environmental concerns of all kinds of fibers are currently investigated. However, there is a gap in data regarding the impacts of digestion protocols on fibers integrity. This work focuses on the impact of five commonly used digestion protocols on the seven most produced fibers in traditional textile: three synthetics (polyamide 6.6 (PA 6.6), polyethylene terephthalate (PET) and polyacrylonitrile (acrylic)), one artificial (viscose), two vegetal natural (cotton and flax) and one animal natural (wool). The protocols to be tested were selected based on the literature: 10% KOH at 40 °C for 24 h; 10% KOH at 60 °C for 24 h; diluted NaClO at room temperature (~20 °C) for 15 h; 30% H2O2 at 40 °C for 48 h; Fenton's reagent with 30% H2O2 for 2 h at room temperature (~20 °C). The fibers were characterized before and after digestion. The effects of those protocols on fibers integrity have been assessed using several of their performance parameters. High degradations were observed for PET with 10% KOH 60 °C whereas almost no impact was observed at 40 °C. H2O2 digestion affects mechanical properties of different fibers, particularly PA 6.6. Both protocols should be avoided for synthetic fibers analyses. NaClO digestion mainly affected flax and viscose. Diluted NaClO at room temperature for 15 h, 10% KOH at 40 °C for 24 h and Fenton's reagent are more appropriate to maintain fibers integrity.

Mineral dust is an important component of the climate system, affecting the radiation balance, cloud properties, biogeochemical cycles, regional circulation and precipitation, as well as having negative effects on aviation, solar energy generation and human health. Dust size and composition has an impact on all these processes. However, changes in dust size distribution and composition during transport, particularly for coarse particles, are poorly understood and poorly represented in climate models. Here we present new in-situ airborne observations of dust in the Saharan Air Layer (SAL) and the Marine Boundary Layer (MBL) at the beginning of its trans-Atlantic transport pathway, from the AER-D fieldwork in August 2015, within the peak season of North African dust export. This study focuses on coarse mode dust properties, including size distribution, mass loading, shape, composition, refractive indices and optical properties. Size distributions from 0.1 to 100 µm diameter (d) are presented, fully incorporating the coarse and giant modes of dust. Within the MBL, mean effective diameter (deff) and volume median diameter (VMD) were 4.6 µm and 6.0 µm respectively, giant particles with a mode at 20-30 µm were observed, and composition was dominated by quartz and alumino-silicates at d > 1 µm. Within the SAL, particles larger than 20 µm diameter were always present up to 5km altitude, in concentrations over 10-5 cm-3, constituting up to 40% of total dust mass. Mean deff and VMD were 4.0 µm and 5.5 µm respectively. Larger particles were detected in the SAL than can be explained by sedimentation theory alone. Coarse mode composition was dominated by quartz and alumino-silicates; the accumulation mode showed a strong contribution from sulfate-rich and sea salt particles. In the SAL, measured single scattering albedos (SSAs) at 550nm representing d

In order to model and predict the alteration of medieval potash-containing stained glass, it is necessary to understand the mechanisms of alteration layer formation at the glass surface and its role on the evolution of alteration kinetics. Moreover, the alteration layers observed on stained glasses are particular, as they are often fractured and heterogeneous in terms of thickness, with the appearance of pits and the detachment of scales. Contrary to silicate glasses altered in aqueous environment where the gel layer has a protective role, cracks and scales are harmful to the durability of stained glasses altered in air. In order to address these mechanistic issues, a program of experiments in the laboratory and in the field were performed. The fracturing was shown to be caused by the growth of the alteration layers and amplified by the alternation of humid and dry periods changing the density of hydrated layers. The pitting is initiated by defects at the glass surface and increased in external atmospheric medium as these defects fix the precipitated salts. However, despite fracturing and pitting, the development of an altered layer imposes a diffusive transport of the solution between the external medium and the bulk glass.

International audience; It is important to understand glass alteration mechanisms and to determine their associated kinetics in order to develop models able to predict the alteration of nuclear, basaltic or archaeological glasses. Recent studies revealed that the respective contributions of diffusion, dissolution, condensation and precipitation processes in alteration are still a matter for debate. In this work, the alteration of a medieval-type glass (Si-K-Ca) was investigated as it presents a specific composition (without B and with low Al). Experiments were performed using a dynamic device, at 30 degrees C, at pH 8 and 9 and during 1 month in order to simulate alteration in contact with water (rainfall or condensation). The solution was doped in Si-29 to discriminate between the silicon from glass (mainly Si-28) and from solution. The results showed that the external region of the alteration layer is devoid of modifier cations (K, Ca) and presents a Si-29/Si-28 ratio close to the solution one. This excludes that the alteration layer is a glass skeleton and highlights a progressive hydrolysis/condensation process, even if non-hydrolyzed silica tetrahedra could remain when the Si isotopic equilibrium is not reached. The internal zone appears to be gradually depleted in modifier cations and partly enriched in Si-29, but the thickness of this zone is overestimated using SEM-EDS and SIMS techniques. Even if in these experiments the dissolution mechanism is favored, the contribution of interdiffusion cannot be neglected to explain the weathering of ancient stained glassed windows in the atmosphere. The respective contribution of diffusion and dissolution are also discussed as a function of glass composition and surface texture, as well as of experimental conditions (alkaline pH, renewal of the solution).

Infrared transmission spectra of several molecular gases inside three porous silica samples with pore sizes ranging from 7 nm to several tens of nm have been recorded with a Fourier transform spectrometer. Their analysis shows that consistent values of the percentage of open porosity and average pore size can be retrieved from these non intrusive nor destructive optical measurements. The samples have also been characterized using mercury intrusion/extrusion and the nitrogen sorption method. The results of these different probing techniques are in good agreement when the methods used are adapted to the involved pore size. This consistency demonstrates that light absorption by confined gases is a valuable porosimetry tool.

International audience; This article concerns the determination of the directional emissivity of materials. Several materials (conducting materials or dielectrics) are investigated and the influence of surface roughness is also considered. The experimental method used for the determination is based on the use of a periodic excitation and the recording of the surface temperature variations of the sample using infrared thermography. Several consecutive measurements are performed for emission angles varying from 0° (for the determinat ion of normal emissivity) to 85°. The experimental device developed (SPIDER instrument) is simple compared to existing devices but the variation of directional emissivity is limited to the spectral bandwith of the camera used.

International audience; Climate change and increasing demography press local authorities to look after affordable water resources and replacement of drinking water for city necessities like street and pavement cleaning by more available raw water. Though, the substitution of drinking by non-drinking resources demands the evaluation of sanitary hazards. This article aims therefore to evaluate the contribution of cleaning water to the overall exposure of city dwellers in case of wet pavement cleaning using crossed physical, chemical and biological approaches. The result of tracer experiments with fluorescein show that liquid water content of the cleaning aerosol produced is about 0.24 g m(-3), rending possible a fast estimation of exposure levels. In situ analysis of the aerosol particles indicates a significant increase in particle number concentration and particle diameter, though without change in particle composition. The conventional bacterial analysis using total coliforms as tracer suggests that an important part of the contamination is issued from the pavement. The qPCR results show a more than 20-fold increase of background genome concentration for Escherichia coli and 10-fold increase for Enterococcus but a negligible contribution of the cleaning water. The fluorescence analysis of the cleaning aerosol confirms the above findings identifying pavement surface as the major contributor to aerosol organic load. The physical, chemical and microbiological approaches used make it possible to describe accurately the cleaning bioaerosol and to identify the existence of significantly higher levels of all parameters studied during the wet pavement cleaning. Though, the low level of contamination and the very short time of passage of pedestrian in the zone do not suggest a significant risk for the city dwellers. As the cleaning workers remain much longer in the impacted area, more attention should be paid to their chronic exposure.

This study revisits the measurements of the MULTI-ASSESS and Long Term Soiling programs for understanding physically, and modeling, the processes controlling the soiling of modern glass in polluted conditions. The results show a strong correlation between the size distribution of particles and the evolution of the mass deposited at the surface of the glass. Over observation periods covering more than 2 years, the mass deposition on glass panels sheltered from the rain is observed to accelerate regularly with time at the sites closest to the sources of particulate matter (Roadside sites). At these sites the deposit is also richer in coarse (supermicron) mineral particles than at more distant (Urban Background and Suburban) sites, where the contribution of submicron particles (among which a significant fraction of particulate organic matter) is larger. This size and compositional segregation probably explains that the mass accumulation tends to slow down with time and finally saturate after an estimated duration of more than 10 years at the Suburban sites. The analysis of the correlation between the measured accumulated mass and haze shows that the haze-creating mass efficiency of the deposit decreases progressively as the density of particles increases on the glass panels. This is interpreted as being a consequence of the increasing influence of multiple scattering. A steady-state is eventually obtained when layers of closely packed particles are formed, which occurs for surface masses of the order of a few tens of μg cm−2. After this stage is reached, the haze increases linearly with further mass deposition at a pace conditioned by the size-distribution of the deposit. The parameterization of the evolution of the deposited mass with time, and of the correlation linking this mass to the haze allows proposing a new physically-based model able to predict the development of the haze on sheltered glass. Finally, a comparison of the model predictions with the independent measurements performed at the experimental sites of the AERO program shows that the model is able to simulate correctly the development of the haze at a variety of urban sites ranging from the Suburban to Roadside categories. This predictive tool should help developing conservation strategies adapted to the real environmental conditions of the historical and modern buildings.

This paper presents new results on the composition, size and shape of mineral dust particles from African sources which were obtained by analysis of bulk filter samples collected in June 2007 onboard the BAe-146 research aircraft of the Facility for Airborne Atmospheric Measurements (FAAM). The aircraft was operated over Mauritania, Mali and Niger during the Geostationary Earth Radiation Budget Intercomparisons of Longwave and Shortwave radiation (GERBILS) campaign. Dust sampled during the campaign originated from various sources, including locally in the Sahel as a result of large-scale convective activity. Regardless of origin, clays (illite, kaolinite) dominated the total volume (79–90%); the remainder was composed of quartz, calcium-rich minerals (calcite, dolomite, gypsum) and alkali feldspars. Iron oxides, measured using a selective chemical extraction method, accounted for 1–3% of the total dust mass. The dependence of particle number size and shape distribution on the origin of dust seems minor too, although our results might be slightly misleading due to the fact that those kinds of data have been gathered on flights when dust had comparable origins and residence time. Mineral dust is only weakly absorbing in the mid-visible wavelengths (single scattering albedo ω0 > 0.95 at 550 nm), and ω0 measured values can be reproduced by measuring the bulk fractions of the major minerals, i.e. clays, quartz, calcite and iron oxides. At this wavelength, knowledge of the nature of clays and iron oxides, or the state of mixing of the minerals, does not induce significant differences in the results. A more precise description of the nature of clays and iron oxides is necessary at lower wavelengths owing to larger differences in their spectral optical properties. In particular, knowledge of the nature of the dominant clay is important for determining light scattering in the backward hemisphere. Copyright © 2011 Royal Meteorological Society and British Crown Copyright, the Met Office

International audience; The aim of this work was to compare the fractal characteristics, Df and kf, the primary particle diameter, Dpp, the gyration diameter of aggregates, Dg, and the overlap coefficient, Cov, of carbon nanoparticle aggregates produced by an ethylene diffusion flame and sampled by means of four commonly used techniques. The first method involves a thermophoretic piston probe (TPP) which inserts a TEM grid into the flame. Three other methods were applied at the outlet of a dilution device, also inserted in the flame. The first of these used a nuclepore filtration sampler (NFS), and is based on filtration of particles onto a polycarbonate membrane. The second, post dilution method, the insertion particle sampler (IPS), inserts a TEM grid, perpendicular to the aerosol flow. Similar to TPP, the last method is a thermophoretic particle sampler (TPS) sampling directly onto a TEM grid. After collection, the samples are stored in the dark either, (1) in a nitrogen filled cell at low humidity or, (2) in ambient air for studying atmospheric ageing. Good agreement was observed between TPP, TPS, and IPS indicating that the dilution induced for TPS and IPS does not significantly change the morphology of soot. On the other hand, the NFS protocol tended to overestimate the overlap coefficient and the size of primary particles and aggregates. Finally, with regard to the aging effect, we found that kf and Dpp evolve slowly during storage in the atmosphere while Df, was insensitive to the storage conditions. However, the overlap coefficient increased and the gyration diameter decreased as a function of storage duration, while storage under nitrogen tended to reduce these changes.

International audience; High intensity hadron beam accelerators have been recently proposed and developed either for the production of high intensity secondary beams for Nuclear and Particle Physics research (EURISOL, SPIRAL2, FAIR), or Applied Physics in the field of Accelerator Driven System and waste transmutation (EUROTRANS). For these applications, high power Linear Accelerator (LINAC) are planned to produce and accelerate hadron beams up to 1 GeV. Both commissioning and operation of these accelerators require dedicated beam instrumentation able to monitor and characterize on line as completely as possible the produced beams having a power in the range of 1 MW. Beam current, transverse beam centroïd position and profiles and beam energy are the most important characteristics that have to be measured. Due to the high average power of the beam, nondestructive or at least minimally intercepting beam sensors are required. Beam instrumentation for IPHI (CEA/DSM and CNRS/IN2P3 collaboration) which is a high intensity proton (3 MeV, 100 mA, CW operation) injector initially designed to be a possible front end for this kind of LINAC is under realization. Beam diagnostics already under operation, developments in progress will be described and will introduce a more general description of high power beam instrumentation.

International audience; The development, manufacturing and commercialization of nanomaterials require traceable characterisation processes for quality control and safety of both the exposed workers and final customers. Even if the production batches are considered to be compliant with the industrial applications intended by manufacturers, it is necessary to study the reproducibility of the manufacturing process of nanomaterials independently, so as to determine the variability of key physico-chemical properties of nano-objects from one batch to another.In this study, a metrological approach was employed, using different traceable analytical techniques (X-Ray Diffraction, Transmission Electron Microscopy, Nitrogen physisorption with Brunauer–Emmett–Teller method, X-Ray Fluorescence, Scanning Mobility Particle Sizer and Aerodynamic Particle Sizer) to develop robust, reproducible and statistical methods to evaluate the impact of batch variability on physico-chemical properties of manufactured titanium dioxide and silicon dioxide nano-powders (crystalline structure, crystallite size, primary particle size, specific surface area, chemical composition and the dustiness of nanopowders).Five references of manufactured titanium dioxide nanoparticles and silicon dioxide nanoparticles were characterized with the developed measurement protocols. The reproducibilities of five batches by reference were overall inferior to 10% for crystalline structures, primary particle sizes, specific surface areas and the chemical composition of major components (TiO2 and SiO2) of the nanopowders studied (k = 1). As for the size distributions of released particles from dustiness tests, reproducibility for the modal and mean diameters ranged between 2% and 27%. Moreover, a large variation of nanopowder dustiness was obtained for the same material type (TiO2 or SiO2). This could point out that the physico-chemical properties of nanopowders, linked to the manufacturing process, have a strong impact on the dustiness parameter.

Black crusts (BC) on selenite, i.e. gypsum stone used in buildings and monuments in the city of Bologna (northern Italy) have been studied. The crusts have been compared with genetically identical ones encountered on gypsum outcrops in the area surrounding the same city, in a relatively clean rural environment. Because of gypsum's high solubility, also in the past, BC began to form and embed particles of atmospheric aerosol as soon as the stone was used in construction, even though the SO 2 levels in the air were probably much lower than today. Unlike other types of stone (sandstone, limestone, marbles), selenite is currently undergoing a deceleration of dissolution processes, following the acidification of the environment caused by industrialisation. For this reason the BC on selenite are older (up to 580±45 yr), thicker (up to 4 cm) and far more stable than those encountered on other types of building stones used in the same area. The BC are stratified: at the base, in contact with the stone, the crust contains numerous prismatic black particles originating from wood combustion; immediately above the base layer these particles progressively increase; finally, in the outer part of the crust one encounters the characteristic black, spongy spherical fly-ash originating from the combustion of mineral oils. From the chemical point of view, a comparison between urban and rural crusts shows that elements such as C, Si, K, Fe, V, Cr, Ni, Zn, Ga, As and Pb are due to present-day and/or past pollutant sources within the city itself. Moreover, the chemical data from the stratigraphy of the BC show that, while C and K were more abundant in the past than now, elements such as Fe, V, Cr, (Mn, Ni), Cu, (Zn), (Ga), As, Pb characterise recent and current urban atmospheres.

Pollution originating from wood combustion characterised the urban atmospheres of the past and led to the formation of thin grey crusts on the surface of the stone of monuments. The grey crusts discovered on the Heads of the Kings of Juda statues, which adorned the facade of Notre Dame in Paris from the 13th century until 1792, constitute a material record of the effects of this ancient air pollution. The height at which the statues stood suggests that the effect was not the result of a point phenomenon, but was caused by a generalised pollution of the Paris atmosphere at the time.

Experimental conditions characteristic of the urban pollution in many European cities over the last decades were reproduced in a simulation chamber in which samples of limestone were exposed for a period of 12 months, both naked or sprinkled with carbonaceous fly-ash. In agreement with the findings reported in the literature the fly-ash emitted by heavy fuel combustion are highly reactive, undergoing chemical and morphological transformations which give rise to crystals growth, especially gypsum. The development of gypsum crystals was observed overall in close proximity of fly-ash anchoring them to the limestone surface. Samples of the same limestone exposed in the field in a polluted environment for the same period of time led to similar results. The preliminary mechanisms leading to the genesis of sulphated black crusts in polluted environments were thus highlighted. Because of their roughness the embryonic black crusts increase the development of the crust by trapping new particles. This trapping is also facilitated by the wetness of the stone surface leading to the development of hydrated mineral (gypsum) in the water meniscus between fly-ash and stone surface.

Recent restorations of Trajan's Column uncovered two marble fragments bearing traces of pigments, bright red (minium, hematite) in one case, and yellowish-orange (minium, hematite, clay minerals) in the other. Both were applied to the marble surface on a plaster underlayer. The presence of an underlayer and of surfaces coloured according to subject tells us that the colours were applied deliberately. Although the use of minium plus hematite is confirmed by archaeological finds, there is only a good probability that the colours were applied on the column at the time of its completion.

The interaction between today’s polluted urban atmosphere and materials leads to the formation of sulphated black crusts containing industrial fly-ash. While many historical documents report the existence of polluted air in towns prior to the modern industrial era, such descriptions have not so far been substantiated by any scientific analysis of samples of older interactions. A new approach is proposed, based on the study of crusts found in Arles and Bologna, which formed in the periods 1180–1636, and 1530–1887, respectively. They are grey, mostly calcitic, and contain wood debris and micrometric siliceous or alumino-silicated spherules. The same tracers were also encountered in the smoke from experimental wood fires. This approach confirms the presence of air polluted by wood combustion in the towns of Southern France and Northern Italy during the Medieval up to pre-industrial age. Such information, near to the source, completes the evidence provided in written documents, as well as the data obtainable, farther from the sources, using core samples of glaciers, lakes and marine sediments.

The methodology of protecting the European stained glass windows against environmental risk (e.g. meteorological factors, air pollution, microorganisms) by means of an external glazing is not new. In spite of many scientific studies carried out in the last 20 years, some questions were still up for discussion. The European VIDRIO (2002–2005) project gave an answer to these questions. The research carried out by the different project partners established a new multidisciplinary approach aimed at evaluating the efficiency of the protective glazing systems and their effects on stained glass windows conservation, and finally at assessing the most appropriate strategy to preserve stained glass windows. Scientific results showed that the so-called isothermal glazing (i.e. ventilation by the air coming from the inside of the building) protected efficiently the ancient stained glass window from environmental attack (i.e. rain, pollutants, condensation, thermal shocks) with very limited secondary effects. The scientific research highlighted that its efficiency was strongly related to the technical design of the protective system. In particular, the ventilation and the size of the interspace had to be carefully considered. The research developed within the VIDRIO project was turned into general recommendations to the owners and practitioners on the best practice for the stained glass windows future conservation.

Transmission spectra of gases confined (but not adsorbed) within the pores of a 1.4-cm-thick silica xerogel sample have been recorded between 2.5 and 5 μm using a high-resolution Fourier transform spectrometer. This was done for pure CO, CO2, N2O, H2O, and CH4 at room temperature and pressures of a few hectopascals. Least-squares fits of measured absorption lines provide the optical-path lengths within the confined (LC) and free (LF) gas inside the absorption cell and the half width at half maximum ΓC of the lines of the confined gases. The values of LC and LF retrieved using numerous transitions of all studied species are very consistent. Furthermore, LC is in satisfactory agreement with values obtained from independent measurements, thus showing that reliable information on the open porosity volume can be retrieved from an optical experiment. The values of ΓC, here resulting from collisions of the molecules with the inner surfaces of the xerogel pores, are practically independent of the line for each gas and inversely proportional to the square root of the probed-molecule molar mass. This is a strong indication that, for the studied transitions, a single collision of a molecule with a pore surface is sufficient to change its rotational state. A previously proposed simple model, used for the prediction of the line shape, leads to satisfactory agreement with the observations. It also enables a determination of the average pore size, bringing information complementary to that obtained from nitrogen adsorption porosimetry. © 2013 American Physical Society.

Results of an interlaboratory comparison on size characterization of SiO2 airborne nanoparticles using on-line and off-line measurement techniques are discussed. This study was performed in the framework of Technical Working Area (TWA) 34 - "Properties of Nanoparticle Populations" of the Versailles Project on Advanced Materials and Standards (VAMAS) in the project no. 3 "Techniques for characterizing size distribution of airborne nanoparticles". Two types of nano-aerosols, consisting of (1) one population of nanoparticles with a mean diameter between 30.3 and 39.0 nm and (2) two populations of non-agglomerated nanoparticles with mean diameters between, respectively, 36.2-46.6 nm and 80.2-89.8 nm, were generated for characterization measurements. Scanning mobility particle size spectrometers (SMPS) were used for on-line measurements of size distributions of the produced nano-aerosols. Transmission electron microscopy, scanning electron microscopy, and atomic force microscopy were used as off-line measurement techniques for nanoparticles characterization. Samples were deposited on appropriate supports such as grids, filters, and mica plates by electrostatic precipitation and a filtration technique using SMPS controlled generation upstream. The results of the main size distribution parameters (mean and mode diameters), obtained from several laboratories, were compared based on metrological approaches including metrological traceability, calibration, and evaluation of the measurement uncertainty. Internationally harmonized measurement procedures for airborne SiO2 nanoparticles characterization are proposed. © 2013 Springer Science+Business Media Dordrecht.

The Lausanne Atmospheric Simulation Chamber (LASC) has been constructed with the aim of studying the SO2 effects on different materials. It allows the carrying out of numerous measurements on large stone samples simultaneously and on line. The behaviour of two carbonatic stone types (limestone and sandstone), either naked or covered with fly ash or soot particles, exposed at the following conditions, SO2 = 125 ppb (340 μg m−3), NO2 = 50 ppb (98 μg m−3), relative humidity = 79%, temperature = 13°C, has been studied. This experiment has been carried out over a 1 yr period. It has been observed that SO2 deposition velocity decreases with time and in different ways for each of the two stone types, naked or covered with fly ash or soot particles. During the first four months, the deposition velocity is higher on naked stones; later on, it is higher on the stone samples covered with fly ash. Throughout the experiment the SO2 deposition velocity on stone samples covered with soot particles is lower than on naked samples and those covered by fly ash. Finally, the values of SO2 deposition velocity are confirmed by the chemical analysis of sulphur in the samples. Sulphur is present from the stone surface down to about 0.8 mm depth.

Fly ash produced by coal combustion using two types of desulphurization process were studied: a conventional pulverized coal boiler equipped with lime injection (PCL ash), and a circulating fluidized bed combustion boiler with limestone injection (CFBC ash). The ashes were characterized completely: granulometry, morphology, mineralogy, chemical composition and behaviour to water contact. Both PCL ash and CFBC ash present similar features: fine granulometry, presence of anhydrite phase and sulphate content. However, PCL ash also shows lots of spherical particles, unlike CFBC ash, and a much higher lime content, due to the lower desulphurization rate in PC boilers. Unlike CFBC ash, most of the trace elements in PCL ash show an inverse concentration-particle size dependence. Leachates obtained from both samples are rich in soluble salts [CaSO4 and Ca(OH) 2] and arsenic and selenium are prevented from solubilizing by high lime content. In wetted PCL ash, the formation of ettringite crystals stabilizes calcium and sulphate ions. Simultaneously, arsenate, selenate and chromate anions are trapped in the crystal. CFBC ash does not really harden because the lime content is too low. However, the leached selenium concentration is cut down in wetted CFBC ash samples. © 1996 ISWA

[1] Dust samples were collected onboard the UK community BAe-146 research aircraft of the Facility for Airborne Atmospheric Measurements (FAAM) operated over Niger during the winter Special Observation Period of the African Monsoon Multidisciplinary Analysis project (AMMA SOP0/DABEX). Particle size, morphology, and composition were assessed using single-particle analysis by analytical scanning and transmission electron microscopy. The aerosol was found to be composed of externally mixed mineral dust and biomass burning particles. Mineral dust consists mainly of aluminosilicates in the form of illite and kaolinite and quartz, accounting for up to 80% of the aerosol number. Fe-rich particles (iron oxides) represented 4% of the particle number in the submicron fraction. Diatoms were found on all the samples, suggesting that emissions from the Bodele depression were also contributing to the aerosol load. Satellite images confirm that the Bodele source was active during the period of investigation. Biomass burning aerosols accounted for about 15% of the particle number of 0.1–0.6 μm diameter and were composed almost exclusively of particles containing potassium and sulfur. Soot particles were very rare. The aspect ratio AR is a measure of particle elongation. The upper limit of the AR value distribution is 5 and the median is 1.7, which suggests that mineral dust particles could be described as ellipsoids whose major axis never exceeds 1.9 × Dp (the spherical geometric diameter). This is consistent with other published values for mineral dust, including the recent Aerosol Robotic Network retrieval results of Dubovik et al. (2006).

As part of the MULTI-ASSESS and VIDRIO EC projects, the soiling of modern glass is characterised in various European urban atmospheres. Our original methodology relies on crossed chemical measurements of the deposit (evaluation of the ion, elemental and organic carbon contents, and subsequent “mass closure”) and exhaustive measurements of glass optical properties (light reflectance, transmittance and absorption). Samples were exposed sheltered from rain in Athens, Krakow, London, Montelibretti (Italy), Prague and Troyes (France), during increasing exposure durations, up to more than two years. Although a slowing down of the deposition rate is observed for some species at some sites, no obvious saturation phenomenon seems to occur for the particle deposition. The chemical composition of the deposit is shown to reflect the atmospheric environment of the exposure site. Some post-deposit evolutions, such as the disappearance of ammonium and possibly of particulate organic matter, are found to occur. For thin deposits, the glass optical properties (e.g. light absorption and diffuse transmittance) are found to evolve quasi-linearly with species concentrations (EC and ions, respectively). However, for conditions creating heavier deposits such as long time exposures in rather polluted environments, a saturation phenomenon is observed. Using a simple model, light absorption, which is primarily due to EC particles, is shown to reach the saturation level (S) for A≈16% and the concentration for which the semi-saturation level is reached (C1/2) is found to be about 15 μgC of EC/cm2. For diffuse transmittance, due to scattering species, these parameters are found to be about 30% and 65 μg of ions/cm2, respectively. These values may be considered as representative of the soiling in Europe.

International audience; Several lines of evidence suggest that early Mars once had liquid water on its surface, a denser atmosphere and a mild climate. Similar environmental conditions led to the origin of life on the Earth more than 3.5 billion years ago; consequently, life might also have originated on Mars. The Viking landers searched for evidence of organic molecules on the surface of Mars, and found that the Martian soil is depleted in organics at ppb levels at the landing sites. We contend that inorganic compounds could give us interesting clues as to the existence of possible biological activity in future astrobiological missions to Mars. Consequently, we have investigated the physical and chemical properties of calcite, which could be expected on Mars because liquid water was certainly present on the surface of early Mars and carbon dioxide was abundant in its atmosphere. Calcite is interesting because on Earth this mineral is produced by abiotic processes as well as by biological activity. One may suppose that crystalline defects and trace element in the crystal lattice and the growth speed of biotic calcites must indicate a difference between them and pure abiotic calcites. We investigated twelve different terrestrial calcite samples from various origins: biotic, diagenetic and abiotic. The minerals were studied by X-ray diffraction and electron scanning microscopy to determine their mineralogical and chemical composition, and differential thermal analysis coupled to thermogravimetric analysis (DTA-TG) to determine their thermal behavior. Our results show that the thermal degradation of abiotic calcite starts at a temperature at least 40°C higher than the degradation temperature of any biotic calcite investigated. Consequently, in the case of a Martian in-situ study or in a sample return mission, the analysis of Martian minerals by DTA-TG represents a promising approach to detect evidence of past biological activity on Mars.

Samples of silica-soda-lime float glass, a material selected as a pertinent soiling sensor, were exposed for up to 28 months at four urban sites (Athens, Krakow, London and Prague) and at a semi-urban one (Monte Libretti, near Rome), sheltered from rain. This exhaustive experience permitted to complete and to test the generalisation ability of the results previously obtained on the same material, exposed according to the same protocol, during 24 months, at a single site (Paris). The model previously fitted for the Paris experiment, the Hill equation, could be successfully generalised for four other sites of exposure (Athens, Krakow, Prague and Rome). The analytical form of this model was interpreted in terms of a physical description of the soiling phenomenon. Some of the model coefficients were different from one site to another, depending on the specific environment of exposure (air pollution levels, meteorological factors), while the other ones were rather equivalent. The analysis of the model coefficients, on the one hand, led to an estimation of the period after which soiling is close to its saturation level, and on the other hand, it will permit to correlate these coefficients to the environmental factors, in order to select the most appropriate ones for building dose-response functions for soiling, with broad geographical application.

Modern silica-soda-lime float glass samples were exposed to background pollution conditions in Paris, sheltered from rain, during 1, 2, 6, 12 and 24 months. Analytical scanning electron microscopy pointed to the importance of soot particles and soluble salts as fine and coarse deposited particles. Four pertinent soiling parameters were measured: total mass of deposited particles (by weighing), mass of total carbon (by thermo-coulometry), mass of water soluble ions (by ion chromatography on glass surface rinsing water) and haze (by spectrophotometry). Model fitting to experimental data showed a continuous increase of soiling in time, following a variable slope sigmoid (Hill equation) for all the four soiling parameters. This similar evolution allowed defining one general model for soiling.

Fine particulate matter present in urban areas seems to be incriminated in respiratory disorders. The aim of this study was to relate physicochemical characteristics of PM2.5 (particulate matter collected with a 50% efficiency for particles with an aerodynamic diameter of 2.5 microm) to their biological activities toward a bronchial epithelial cell line 16-HBE. Two seasonal sampling campaigns of particles were realized, respectively, in a kerbside and an urban background station in Paris. Sampled-PM2.5 mainly consist of particles with a size below 1 microm and are mainly composed of soot as assessed by analytical scanning electron microscopy. The different PM2.5 samples contrasted in their PAH content, which was the highest in the kerbside station in winter, as well as in their metal content. Kerbside station samples were characterized by the highest Fe and Cu content, which appears correlated to their hydroxyl radical generating properties measured by electron paramagnetic resonance. Particles were compared by their capacity to induce cytotoxicity, intracellular ROS production, and proinflammatory cytokine release (GM-CSF and TNF-alpha). At a concentration of 10 microg/cm2, all samples induced peroxide production and cytokine release to the similar extent in the absence of cytotoxicity. In conclusion, whereas the PM2.5 samples differ by their PAH and metal composition, they induce the same biological responses likely either due to components bioavailability and/ or interactions between PM components.

International audience; During the major part of the Mediterranean Intensive Oxidant Study (MINOS) campaign (summer 2001, Crete Isl.), the Marine Boundary Layer (MBL) air was influenced by long range transport of biomass burning from the northern and western part of the Black Sea. During this campaign, carbonaceous aerosols were collected on quartz filters at a Free Tropospheric (FT) site, and at a MBL site together with size-resolved distribution of aerosols. Three Evolution Gas Analysis (EGA) protocols have been tested in order to better characterize the collected aged biomass burning smoke: A 2-step thermal method (Cachier et al., 1989) and a thermo-optical technique using two different temperature programs. The later temperature programs are those used for IMPROVE (Interagency Monitoring of Protected Visual Environments) and NIOSH 5040 (National Institute of Occupational Safety and Health). Artifacts were observed using the NIOSH temperature program and identified as interactions between carbon and dust deposited on the filter matrix at high temperature (T>550ºC) under the pure helium step of the analysis. During the MINOS campaign, Black Carbon (BC) and Organic Carbon (OC) mass concentrations were on average respectively 1.19±0.56 and 3.62±1.08 mgC/m3 for the IMPROVE temperature program, and 1.09±0.36 and 3.75±1.24 mgC/m3 for the thermal method. Though these values compare well on average and the agreement between the Total Carbon (TC) measurements sample to sample was excellent (slope=1.00, r2=0.93, n=56), important discrepancies were observed in determining BC concentrations from these two methods (average error of 33±22%). BC from the IMPROVE temperature program compared well with non-sea-salt potassium (nss-K) pointing out an optical sensitivity to biomass burning. On the other hand, BC from the thermal method showed a better agreement with non-sea-salt sulfate (nss-SO4), considered as a tracer for fossil fuel combustion during the MINOS campaign. The coupling between these two methods for determining BC brings here new insights on the origin of carbonaceous aerosols in a complex mixture of different sources. It brings also to our attention that important deviations in BC levels are observed using three widely used EGA's techniques and most probably none of the EGA tested here are well adapted to fully characterize this aerosol mixture. Spherical, smooth and silico-aluminated fly-ash observed by an Analytical Scanning Electron Microscope (ASEM) confirm the influence of coal combustion on the carbonaceous aerosol load throughout the campaign. A rough calculation based on a BC/nss-SO4 mass ratio suggests that biomass burning could be responsible for half of the BC concentration recorded during the MINOS campaign. From the plot of BC as a function of TC, two linear correlations were observed corresponding to 2 times series (before and after 12 August). Such good correlations suggest, from a first look, that both BC and OC have similar origin and atmospheric transport. On the other hand, the plot of BC as a function of TC obtained from the 2-step thermal method applied to DEKATI Low Pressure Cascade Impactor samples does not show a similar correlation and points out a non conservative distribution of this ratio with 2 super micron modes enriched in OC, correlated with sea salt aerosols and probably originating from gas-to-particle conversion.

Du 18 au 19 novembre 2010 s’est tenu au Conservatoire national des arts et metiers (Cnam) un « Colloque sur l’enseignement de la physique subatomique », a l’initiative des divisions Physique nucleaire et Particules et champs, de l’interdivision Physique des accelerateurs et technologies associees, ainsi que de la commission Enseignement de la Societe Francaise de Physique.

Une synthese des travaux et des interpretations du Laboratoire interuniversitaire des systemes atmospheriques concernant l'alteration de la pierre et du verre par la pollution atmospherique est presentee. Sur les facades des bâtiments, quels que soient les materiaux (pierre ou verre), les zones exposees a la pluie sont claires et erodees, celles qui en sont abritees s'assombrissent par formation de croutes noires contenant entre autres des particules anthropiques (cendres volantes et suies) cimentees par du gypse. Sur les pierres calcaires, une sulfatation vers la profondeur se produit simultanement. Sur les pierres calcaires poreuses, les croutes noires se detachent periodiquement en formant des plaques noires, laissant un dessin en puzzle blanc-gris-noir sur la surface du substrat. Des croutes anciennes, temoins de la pollution atmospherique ante-industrielle, ont ete analysees : elles contiennent des debris de bois imbrules. La quantification des effets de la pollution atmospherique peut se faire soit directement sur des bâtiments d'âges differents, soit au cours d'experiences de simulation sur le terrain ou au laboratoire dans des chambres de simulation. Dans les deux derniers cas, des croutes gypseuses embryonnaires apparaissent des la premiere annee. La conclusion recense de nombreuses questions encore sans reponse effets des polluants autres que le soufre, effets sur d'autres materiaux...

Publisher Summary Pollution linked to the combustion of wood is characteristic of the atmosphere of the cities in the past. It led to the development of thin grey crusts on the surface of the stones of monuments. The grey crusts were discovered on the Heads of Kings of Juda Statues, present on the western facade of Notre-Dame in Paris from the 13 th Century to 1792. These thin grey crusts are the material witnesses of the effects of the ancient air pollution, prevalent during the French revolution and the period immediately before it. This chapter focuses on the research conducted on the character and evolution of urban air pollution in the past; and the comparison of results with those derived from studies on the modern industrial black crusts. Several analytical techniques were used to highlight the main physicochemical and mineralogical characteristics of the grey crusts: colorimetric technique, X-ray diffraction, and photon microscopy. Many of the characteristics of the ancient grey crusts of the Heads of Kings of Juda directly contrast with those of the modern day black crusts: color, texture, thickness, and chemicomineralogical nature of the crusts and of the prismatic or spherical particles embedded in the matrix. Diffractometric analysis of the modem black crusts highlights the presence of the same minerals as those found in the ancient crusts of the Heads, but in different proportions greater amounts of gypsum than calcite, followed by quartz and weddellite. A further major difference between the ancient grey crusts and the modern black crusts lies in the kind of particles contained in the gypsum-calcite cement. While the grey crusts only contain the residues of incomplete wood combustion, the modern crusts embed microspheres, which turn out to be fly-ash released into the atmosphere by the combustion of coal or heavy fuel.

Publisher Summary Carbonaceous fly-ash, particularly those emitted by heavy fuel oil combustion, has a strong physicochemical reactivity. They contain many sulfured chemical species, in particular sulfates along with metals such as vanadium, iron, and nickel. This chapter describes the role of carbonaceous fly-ash in the nucleation of gypsum crystals and in the development of incipient sulfated black crust on carbonate surface. This study is conducted by comparing simulation chamber data with those obtained in the field. Embryonic black crust forming over 12 months through interaction between carbonaceous fly-ash and samples of Jaumont limestone in the controlled atmosphere of a simulation chamber are compared with those forming in the field on the same carbonate stone, over the same time period in a real polluted atmosphere. The Jaumont limestone samples were placed inside the LASC, either naked or sprinkled with fly-ash. Similarly, Jaumont field samples were collected and examined with ASEM. The chapter discusses the results from both samples and compares them to draw conclusions. On the basis of simulation chamber and field data obtained over 12 months, the study of the morphology, mineralogy, and chemical composition of the deposits and associated neocrystallizations indicates that they represent the first stage of black crust development. The fly-ash appears to play a crucial role in the formation of black crusts because they facilitate the precipitation of gypsum, which constitutes the predominant mineral in the black crusts.

Technological advances in nanomaterials have allowed the development of new applications in industry, increasing the probability of finding airborne manufactured and engineered nano-objects in the workplace, as well as in ambient air. Scientific studies on health and environmental risks have indicated that airborne nano-objects in ambient air have potential adverse effects on the health of exposed workers and the general population. For regulatory purposes, ambient measurements of particulate matter are based on the determination of mass concentrations for PM10 and PM2.5, as regulated in the European Directive 2008/50/EC. However, this legislation is not suitable for airborne manufactured and engineered nano-objects. Parameters characterising ultrafine particles, such as particle number concentration and size distribution, are under consideration for future health-based legislation, to monitor workplaces and to control industrial processes. Currently, there are no existing regulations covering manufactured airborne nano-objects. There is therefore a clear, unaddressed need to focus on the toxicology and exposure assessment of nano-objects such as titanium dioxide (TiO2), which are manufactured and engineered in large quantities in industry. To perform reliable toxicology studies it is necessary to determine the relevant characteristics of nano-objects, such as morphology, surface area, agglomeration, chemical composition, particle size and concentration, by applying traceable methods. Manufacturing of nanomaterials, and their use in industrial applications, also require traceable characterisation of the nanomaterials, particularly for quality control of the process. The present study arises from the OECD WPMN sponsorship programme, supported by the French Agency for Environmental and Occupational Health Safety (ANSES), in order to develop analytical methods for the characterization of TiO2 nanoparticles in size and count size distribution, based on different techniques to characterize five different manufactured TiO2 nanoparticles. In this study, different measurement techniques have been implemented: Transmission Electron Microscopy (TEM), Scanning Mobility Particle Sizer (SMPS) and Aerodynamic Particle Sizer (APS). The TEM results lead to a relatively good agreement between data from the manufacturer and our characterizations of primary particle size. With regard to the dustiness, the results show a strong presence of agglomerates / aggregates of primary particles and a significant presence of emitted airborne nanoparticles with a diameter below 100 nm (composed of isolated primary particles and small aggregates / agglomerates formed from a few primary particles): the number proportion of these particles varies from 0 to 44 % in the measurement range 14-360 nm depending on the types of powders and corrections of measurements.

Summary The limestones (“tuffeau”) of the ”Cloitre du Grand Moutiers” and the “Salle Capitulaire” in the Fontevraud Abbey (Loire Valley, France) contain two types of mineral microspherules : - in the non-altered substrate stone : microspherules (10 μm in diameter), only siliceous in composition and probably biogenic in origin. - in the altered black crust : alumino-silicate or metallic microspherules (1-5 μm in diameter) associated with gypsum crystals. A study by means of Analytical Scanning Electron Microscopy has been performed on the microspherules both in non-altered and altered stone. The chemical composition of the microspherules associated with gypsum is the same as that of industrial fly-ash emitted by coal-burning power plants. Their presence in the altered crusts of carbonatic rocks is in agreement with a previous study. Their role in the formation of the sulphate crust is probably of major importance. The origin of fly-ash has been studied by back trajectories of air masses during the sampling period.

Glassy microspherules collected from the plume of Etna volcano show a surprising compositional variability with SiO 2 from 48 to 90 wt%, despite a very homogeneous basaltic source magma (SiO 2 = 48%). This same variability is also observed in individual microspherules from their inner to outer parts. The most plausible hypothesis concerning these compositional variabilities is the interaction of the microspherules with the volcanic gases inside the crater prior to their atmospheric dispersal. In order to study this compositional variability we experimentally exposed basaltic glass to volcanic gases at Etna. The resulting glass composition documents a fundamental alteration mechanism, involving an apparent leaching process that can rapidly form nearly pure silica. Because microspherules erupted directly into the air from lava fountains remain unaltered, the duration of microspherules within a gas plume can explain the chemical variability of glass alteration. A major implication for the origin of glassy atmospheric particulates is that chemical compositions cannot be used as a reliable indicator of their source (e.g., meteoric, volcanic, anthropogenic).

Μη διαθέσιμη περίληψη, no abstract