Prospection géophysique multi-méthodes du pergélisol alpin dans le Sud des Alpes Suisses

La prospection géophysique multi-méthodes du pergélisol alpin dans la Valle di Sceru (sud des Alpes suisses, Canton du Tessin) à l’aide de méthodes thermiques (température des sources et de la surface du sol), à l’aide de méthodes thermiques (température des sources et de la surface du sol), de résistivité (sondage géoélectrique) et électromagnétiques (VLF-R et conductivimètre EM31) a permis de déterminer la répartition et les caractéristiques du pergélisol dans les glaciers rocheux et les éboulis étudiés. La répartition du pergélisol dans les glaciers rocheux est assez homogène et généralement contrôlée par les conditions topoclimatiques du site. Pour les éboulis, au contraire, l’extension spatiale du pergélisol est le plus souvent hétérogène et la probabilité d’occurrence du pergélisol diminue en direction du haut du versant. Les processus qui semblent contrôler la répartition du pergélisol dans les éboulis sont les échanges d’air advectifs, la redistribution de la neige (par le vent et les avalanches) et le granoclassement longitudinal. L’étude a également permis de tester les méthodes électromagnétiques utilisées et de les valider pour la prospection du pergélisol alpin.The multi-method geophysical prospecting of alpine permafrost in the Sceru Valley (southern Swiss Alps, Ticino Canton) with thermal methods (spring temperature and ground surface temperature monitoring), DC-resistivity method (Vertical Electrical Sounding) and electromagnetic methods (VLF-R and conductivity-meter EM 31), allowed determining the permafrost distribution and characteristics in the investigated rockglaciers and talus slopes. The permafrost distribution is quite homogeneous in the rockglaciers, where it is generally controlled by the topoclimatic conditions of the site. In the talus slopes, the permafrost distribution is quite heterogeneous and the probability of permafrost occurrence decreases upslope. The main processes controlling this particular permafrost distribution are the chimney effect, the redistribution of snow by wind and avalanches and, finally, the increase of grain size downslope. The study also allowed testing electromagnetic methods and to validating their application in the prospecting of alpine permafrost

TTAS a new stilbene derivative that induces apoptosis in Leishmania infantum.

Leishmania parasites are able to undergo apoptosis (programmed cell death), similarly to mammalian cells. Recently it was demonstrated in vitro the anti-leishmanial effect of some natural and synthetic stilbenoids including resveratrol and piceatannol. In this study we evaluated the Leishmanicidal activity of a pool of stilbene derivatives which had previously shown high apoptotic efficacy against neoplastic cells. All the compounds tested were capable to decrease the parasite viability in a dose-dependent manner. Trans-stilbenes proved to be markedly more effective than cis-isomers. This was different from that observed in tumor cells in which cis-stilbenes were more potent cytotoxic agents. Trans-3,4',5-trimethoxy-3'-amino-stilbene (TTAS) was the most active stilbene showing in Leishmania infantum a LD(50) value of 2.6 μg/mL. In contrast TTAS showed a low toxicity when tested on normal hemopoietic cells. This compound induced apoptosis in parasites by disrupting the mitochondrial membrane potential. Moreover it shows the ability to block Leishmania parasites in G(2)-M phase of cell cycle in agreement with the data obtained by affinity chromatography that identify tubulin as the putative target of TTAS. In conclusion, our results indicate that some stilbene derivatives are highly effective as anti-leishmanial agents and TTAS represents a pro-apoptotic agent in Leishmania parasites that merit further in vivo investigation

Factors controlling the water quality of rock glacier springs in European and American mountain ranges

Rock glaciers (RGs) provide significant water resources in mountain areas under climate change. Recent research has highlighted high concentrations of solutes including trace elements in RG-fed waters, with negative implications on water quality. Yet, sparse studies from a few locations hinder conclusions about the main drivers of solute export from RGs. Here, in an unprecedented effort, we collected published and unpublished data on rock glacier hydrochemistry around the globe. We considered 201 RG springs from mountain ranges across Europe, North and South America, using a combination of machine learning, multivariate and univariate analyses, and geochemical modeling. We found that 35 % of springs issuing from intact RGs (containing internal ice) have water quality below drinking water standards, compared to 5 % of springs connected to relict RGs (without internal ice). The interaction of ice and bedrock lithology is responsible for solute concentrations in RG springs. Indeed, we found higher concentrations of sulfate and trace elements in springs sourcing from intact RGs compared to water originating from relict RGs, mostly in specific lithological settings. Enhanced sulfide oxidation in intact RGs is responsible for the elevated trace element concentrations. Challenges for water management may arise in mountain catchments rich in intact RGs, and where the predisposing geology would make these areas geochemical RG hotspots. Our work represents a first comprehensive attempt to identify the main drivers of solute concentrations in RG water

Open source GIS platform for water resource modelling: FREEWAT approach in the Lugano Lake

The FREEWAT platform is an innovative Free and Open Source water resource modelling platform integrated in the QGIS geospatial software, using the SpatiaLite database, and including globally-established simulation codes from the USGS MODFLOW models family. This paper demonstrates its application to the Lugano Lake basin case study, Switzerland and Italy. Two specific modules of the platform were used to execute data integration and analyses: the Observation Analysis Tool and the Lake Package. The first one is a newly developed module facilitating the integration of time-series observations into modelling by enabling pre- and post-processing in the model environment; the latter is an existing MODFLOW package allowing dynamic evaluation of groundwater/ lakes interaction. In the case study implementation, a participatory approach was adopted to enhance trust and acceptance of results. These show that integration of simulation codes within GIS is highly appreciated. Furthermore, its openness and freeness allow easily sharing of developed analysis and models. Stakeholders also positively evaluated the participatory process as it empowers decision making with a better understanding of model results and uncertainties. The combination of the FREEWAT platform and the participatory approach may constitute a valuable methodology to include scientifically based analysis to be used for policy design and implementation