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International audience; The speciation of both redox reactive and volatile selenium (Se) compounds, barely reported in pristine aquatic environments, has never been investigated in remote alpine lakes, considered as sensitive ecosystems to detect the effect of global change. This work presents an integrated investigation on Se distribution and speciation conducted in 20 high altitude pristine lakes from the central-western Pyrenees. Five seasonal sampling campaigns were carried out after snowmelt (June/July) and in early fall (October) for the period 2017–2019. Concentrations of total dissolved Se (TDSe) ranged from 7 to 78 ng L−1, with selenate being ubiquitously observed in most cases (median of 61% of TDSe). Selenite was only occasionally detected up to 4 ng L−1, therefore a fraction of TDSe was presumably in the forms of elemental Se(0) and/or selenides. Depth profiles obtained in different lakes showed the occurrence of such Se(−II, 0) pools in bottom hypoxic to anoxic waters. The production of volatile Se compounds presented a low median total concentration (TVSe) of 33 pg L−1 (range 3–120 pg L−1), mainly in the form of dimethylselenide in subsurface samples (median of 82% of TVSe). The Se concentration in lake waters was significantly correlated with the sulphate concentration (ρ = 0.93, p < 0.0001), demonstrating that it is influenced by erosion and dissolution of Se and S-enriched parent bedrocks. In addition, for Se depleted alpine lake-bedrock systems, long-range transport and wet atmospheric depositions represent a major source of Se for lake waters.

While mercury (Hg) is a major concern in all aquatic environments because of its methylation and biomagnification pathways, very few studies consider Hg cycling in remote alpine lakes which are sensitive ecosystems. Nineteen high-altitude pristine lakes from Western/Central Pyrenees were investigated on both northern (France) and southern (Spain) slopes (1620-2600 m asl.). Subsurface water samples were collected in June 2017/2018/2019 and October 2017/2018 for Hg speciation analysis of inorganic mercury (iHg(II)), monomethylmercury (MMHg), and dissolved gaseous mercury (DGM) to investigate spatial and seasonal variations. In June 2018/2019 and October 2018, more comprehensive studies were performed in four lakes by taking water column depth profiles. Besides, in-situ incubation experiments using isotopically enriched Hg species (

Epoxy–silica hybrids (i.e., as such, enriched with TiO2 and cerium-doped TiO2 nanoparticles), based on a bisphenol (BPA)-free cycloaliphatic precursor, were designed for potential applications as stone conservation multifunctional materials. To this aim, nanoparticles were specifically prepared and their suitability for incorporation into the hybrids was assessed by means of X-ray diffraction (XRD), BET porosimetry, and photocatalytic activity measurements. On the other hand, the organic-inorganic materials, both undoped and doped with nanoparticles, were sol-gel synthesized in methanol starting from 1,4-cycloexanediglycidyether (CHDM-DGE) and 1,8-diaminooctane (DAO), in the presence of silica-forming additives, such as 3-glycidyloxypropyltrimethoxysilane (GPTMS), tetraethyl orthosilicate (TEOS), and isobuthyl (trimethoxy) silane (iBuTMS). A multianalytical methodology was employed for material characterization. The homogeneity, the extent of the epoxy cleavage, and the absence of partially hydrolyzed Si (OR)3 groups in the cross-linked hybrid networks were established thanks to a combination of scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM-EDS), and imaging Raman analysis. Moreover, the thermal, hydrophobic, and chromatic properties of the hybrids were investigated by thermogravimetry/differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), contact angle, and color measurements. Finally, the antimicrobial characterization was studied using a sowing strain of Gram-positive bacteria. The results showed that, among all, one of the epoxy–silica hybrid formulations features some of the main prerequisites to be fulfilled for a successful stone conservation treatment.

One of the effects of the atmospheric CO2 increase is ocean acidification. Over the past 20 years, accurate measurements of the seawater carbonate system have become a high priority because this is the main system controlling seawater acidity. However, this phenomenon has not been widely studied in estuaries, even if they are among the most productive natural habitats in the world, lodging some of the highest biotic diversity and production. Due to that lack of information, this work aims to develop and discuss new strategies for the determination of total alkalinity (TA), one of the most measured parameters in the study of acidification, in estuarine waters in the wide range of salinities that can be found in these systems. For that purpose, a new set of stability constants for the carbonate system was established and compared with those most widely used up to date. For the determination of TA, different approaches were studied for the data treatment of the potentiometric titration data.

International audience; Studies on the CO2 system in alpine lakes are performed by scientists of different areas and, therefore, it is crucial to stablish common procedures to investigate the chemical properties of these ecosystems in order to reach comparable results and perform meaningful long-term studies. In this work, a robust procedure was developed to determine the total alkalinity in high altitude mountain lakes which allows the determination of the CO2 system parameters with improved precision and accuracy. In the potentiometric titration of the samples with HCl, used for the Total Alkalinity determination, the fitting between experimental and calculated titration points was greatly improved by incorporating the contribution of new acid-base species which had not been accounted for in previous works. This methodology can be used not only for alpine lakes but also for other natural water systems where the contribution of an extended set of acid-base species is normally not considered. A modified script has been also developed for the Matlab version of the CO2SYS program which allows an adequate calculation of the rest of the CO2 system parameters. The calculated pKa values of the new acid-base species are consistent in nearly all the lakes, ranging from 6.5 to 7, suggesting the similar nature of the acid-base species in all the lakes and that in the Ayous area a different number and/or type of species could be present. Furthermore, the values of all the chemical parameters studied were explained considering the geochemistry of the bedrock.

This work is focused on the development of an innovative multi-analytical methodology to estimate the impact suffered by building materials in coastal environments. With the aim of improving the in situ spectroscopic assessment, which is often based on XRF and Raman spectrometers, diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy was implemented in the diagnosis study. In this way, the additional benefits from DRIFT were compared to the usual in situ analyses of building materials, which often have interferences from fluorescence and reststrahlen effects. The studies were extended to the laboratory scale by μ-X-ray fluorescence (μ-XRF) cross-section mapping and ion chromatography (IC), and the IC quantitative data were employed to develop thermodynamic models using the ECOS-RUNSALT program, with the aim of rationalizing the behavior of soluble salts with variations in the temperature and the relative humidity (RH). The multi-analytical methodology allowed identification of the most significant weathering agents and classification of the severity of degradation according to the salt content. The suitability of a DRIFT portable device to analyze these types of matrices was verified. Although the Kramers-Kronig algorithm correction proved to be inadequate to decrease the expected spectral distortions, the assignment was successfully performed based on the secondary bands and intensification of the overtones and decreased the time needed for in situ data collection. In addition, the pollutants' distribution in the samples and the possible presence of dangerous compounds, which were not detected during the in situ analysis campaigns, provided valuable information to clarify weathering phenomena.

This work is focused on the development of sustainable stone conservation materials, based on BPA-free epoxy-silica hybrid resins, with consolidating and hydrophobic properties, for long-term treatments. For this purpose, a cycloaliphatic diol, with minor health and environmental associated issues with respect to classic phenolic derivatives, was selected to synthesize a BPA-free bio-based epoxy resins precursor, 2,2,4,4-tetramethyl-1,3-cyclobutanediol diglycidylether (CBDO-DGE). Fourier transform infrared (FT-IR) and Raman spectroscopies were employed to assess the synthesis and clean-up procedures. In addition, both 1H-NMR and 13C-NMR in solution were used to ascertain the structure and purity of the bio-based epoxy. The development of the epoxy thermosets by 1,8- diaminooctane (DAO), triethylenetetramine (TETA) and 5-amino-1,3,3-trimethylcyclohexanemethylamine (IPDA) curing agents was followed by attenuated total reflection infrared (ATR FT-IR) and Raman spectroscopies, whereas their suitability as organic counterpart of the hybrids was established by differential scanning calorimetry (DSC) and thermogravimetric (TGA) measurements. In addition, epoxy-silica hybrids were obtained by exploiting sol-gel technology, carrying out the epoxy hardening reactions also in the presence of (3-glycidyloxypropyl)trimethoxysilane (GPTMS) and octyltriethoxysilane (OcTES), as silica-forming additives. To investigate the properties of the resulting hybrid materials imparted by the selection of the different reactants, various blends were studied by a combination of scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM-EDS), ATR FT-IR and Raman analysis. Furthermore, the assessment of the hybrids tunability as materials for stone conservation was ascertained in terms of thermostability and hydrophobicity by TG-DTA, DSC, dynamic mechanical analysis (DMA) and contact angle measurements.

A flow injection analysis (FIA) method, based on the molybdenum blue formation, has been adapted and successfully optimized in order to use it to measure phosphate in estuarine water samples. Matrix effects have been avoided using the highest peak, and the Schlieren effect (common in FIA analysis) has been minimized by injecting the ascorbic acid with the same sulphuric acid concentration as the molybdate reagent. The concentrations of the reagents have been optimized by a Central Composite Design. The measuring range used was 0.02–0.2 mg L− 1 phosphate and both univariate and multivariate regressions have been compared using a random sample, reaching the same concentration (0.065 ± 0.002 mg L− 1). However, the univariate regression showed lower LODs, 7 μg L− 1 (74 nM) in front of the 10 μg L− 1 (105 nM) reached by the multivariate one. The effectiveness of the developed method was tested with real samples. For this, low-cost conventional equipment easily available to most laboratories has been used, with a LOD low enough to measure estuary samples, and high repeatability.

In this study, the spatial and temporal-distribution of 41-multiclass organic compounds were assessed in three estuaries of the Basque Country, from winter 2016 to winter 2017 by grab (active) sampling methods and an extra campaign combining both, grab and passive sampling methods. Wastewater treatment plant (WWTP) effluents were also evaluated to assess their impact on the estuaries. Moreover, the physicochemical features (phosphate and nitrate concentrations, pH, etc.) of each site were measured and included in the statistical analysis. Anti-inflammatory drugs (diclofenac and acetaminophen), hypertensive drugs (irbesartan and valsartan), a stimulant (caffeine), an artificial sweetener (acesulfame) and a corrosion inhibitor (2-hydroxybenzothiazole) were the most ubiquitous compounds. Due to the stratification of the waters in the estuary of Bilbao two independent sources were identified: WWTP and harbour activities. In the case of Gernika and Plentzia, both are estuaries with a high tidal dilution, and the main sources were localized in the effluents of the WWTPs. In addition to this, the use of POCIS provides an efficient way to monitor emerging pollutants over a relatively long sampling period. Finally, risk quotient (RQ) values of each contaminant were estimated from the maximum values determined at each estuary and WWTP effluent for acute and chronic effects. In the case of acute toxicity the highest RQ values (»1) were obtained for the angiotensin II receptor blockers (telmisartan, eprosartan, etc.), diuron and diclofenac. In the case of the chronic toxicity the highest RQ values (»1) were estimated for caffeine, diclofenac, bezafibrate and sulfadiazine.

Spectroscopic techniques are widely used in the field of analytical chemistry for the determination of a huge number of analytes. The use of diode array spectrophotometers involves the possibility of collecting the whole UV-Vis spectrum, which provides an opportunity to perform a multivariate analysis of the samples. The effectiveness of the use of multivariate data analysis against the univariate counterpart (which is the most common for classic spectroscopic methods) is demonstrated through application in the sulphate determination in seawater samples using a modified turbidimetric method. The original method recommends performing the analysis at 420 nm, this being a univariate analysis. The modification presented uses multivariate methods for the calibration with the whole UV-Vis spectrum from 200 to 800 nm instead of the single measurement at 420 nm. The external calibration shows that there is a matrix effect which can compromise the accuracy of the measurements, so that an in-house Iterative Multivariate Standard Addition Method (IMSAM) was successfully tested in order to avoid this effect. As the spectrum interval was too wide, both Genetic Algorithm (GA) and interval Partial Least Square (iPLS) regression methods were used in order to select the best wavelengths for the regression and back prediction of the samples. The results obtained in this work show that the performance of the method at 420 nm, as the original method recommends, leads to a considerable error and also that the best segment of the spectra for the determination of the sulphate concentration in seawater is from 600 to 800 nm.

In 1819 Alexander Marcet proposed that seawater contains small amounts of all soluble substances and that the relative abundances of some of them were constant. This hypothesis is nowadays known as Marcet's Principle or the principle of constancy of the composition of seawater. Based on this principle, the present research tried to prove that it is possible to detect polluted seawater samples using the seawater H(+) affinity spectrum by the application of the possibilities provided by chemometric tools. Seawater samples were classified using the principal component analysis (PCA) of the HBound spectra of the samples. It was concluded that the sampling points location does not have any influence in the cluster formation, while the season in which they were collected is significant. On the other hand, the seawater composition was calibrated using estuary water samples of different salinities. Once the major constituents were measured, the data analysis concluded that it is possible to make a calibration of the HBound spectrum vs. any of these constituents by means of partial least square (PLS) regression. Thus, the experimental evidence collected in this work confirms that it is possible to detect polluted sea or estuary water samples using these chemometric tools and the H(+) affinity spectrum because with polluted samples these multivariate methods lead to incoherent results. So, suspect polluted zones may be monitored in a simple way with a low cost method and spending much less time.