Monitoring land-cover changes in Mediterranean coastal dunes, northwest Tunisia, using remote sensing data

Coastal dune landscapes are subject to morphological and ecological changes. In many parts of the world, coastal dunes are under severe pressure. The present study illustrates an integrated remote sensing and Geographical Information System (GIS) approach, i.e., geospatial techniques for assessing land-cover dynamics in Zouaraa coastal dunes, located in northwest Tunisia. As a main result, the analysis of the situation in the past six decades indicates that the dune area showed a decreasing trend with up to 31% (i.e., 6198 ha) in favour of forest area, which has increased by up to 6485 ha. The geo-spatial analysis revealed that restoration works have positively contributed to stabilize coastal dune systems with a substantial increase in vegetation cover. An increase in drought frequency and intensity was detected during the 1952-2017 period using the SPEI index, which enhanced the vegetation activity and growth in the study area. The SPEI significantly correlated with vegetation greenness on the 12- and 24-months’ time scales. The croplands, water and buildings in the study area have increased respectively by 6% (i.e., 1256 ha), 13% (i.e., 3073 ha) and 3% (i.e., 719 ha). In contrast, land cover like shrub and bare soil has decreased respectively by 13% (i.e., 3073 ha) and 2% (i.e., 1831 ha) during the same period. Furthermore, this study highlights the importance of the revegetation techniques undertaken for conserving coastal dune systems. The findings of this study allow land-use planning decision makers to manage and improve situations in similar coastal regions.This work was supported by the National Research Institute for Rural Engineering, Waters, and Forestry-INRGREF. Laboratory of Management and Valorization of Forest Resources, Tunisia. This research is part of the project: HYDROMED (PID-2019-111332RB-C21)

Étude des propriétés adsorbantes d’une argile pontée vis-à-vis de Cu

A partir des données macroscopiques (isothermes d'adsorption en fonction du pH) et microscopiques (spectroscopie RMN pour Cd2+ et RPE pour Cu2+) nous proposons un modèle expliquant les interactions à l'interface entre des cations métalliques et une argile pontée par des polycations hydroxyaluminiques. Les piliers forment une phase aluminique ultradispersée entre les feuillets, avec une réactivité similaire à celle de la surface d'une alumine (mais non identique). L'acidité des piliers favorise l'adsorption des cations M2+ à des pH inférieurs à ceux présentés par les oxydes et les hydroxydes d'aluminium

Effect of Preservation and Transport Conditions on SCC in Cow Milk and Losses of Precision Associated with Time Left Before Analysis

The effect of preservation agents (without preservation, potassium dichromate, and bronopol) on the somatic cell count (SCC) of individual cow milk samples was studied at two different times during lactation. Using the fossomatic method, 1050 (experiment 1) and 924 (experiment 2) SCC measurements were carried out on milk samples from 25 and 22 cows of the same lot, respectively. In addition, each individual milk sample was divided into several aliquots and analyzed at different times postcollection (5h, and 1, 2, 3, 4, 5 and 6 days) to evaluate the loss of precision associated to each milk age, depending on whether aliquots were preserved, refrigerated, or not refrigerated. Preservation and refrigeration during milk transport had no significant effects on SCCs in both experiments, which differed in milk SCC levels. Accuracy associated to milk age depended on the lactation stage; errors were much lower when milk was more abundant and the SCC level was thus lower. For practical reasons, milk analysis for SCC should be carried out at the latest 48h postcollection

Study of Pd(II) Adsorption over Titanate Nanotubes of Different Diameters

MATERIAUX+ATR:GBE:HKONon

In situ preparation of zirconium sulfate pillared clay: study of acidic properties

Sulfated zirconium clays were prepared by adding ammonium sulfate to the intercalation solution. The main controlled parameter in this study is the SO4:Zr ratio in solution. The characterization of these catalysts, their acidic properties and their catalytic activities was examined by N-2-BET adsorption, chemical analysis, the adsorption-desorption of basic molecules, the conversion of n-hexane and the transformation of isopropanol. Two different types of SO4-Zr polycation binding were advanced and correlated with the acidic properties of these solids. To enhance the acidity of the sulfated zirconium clay, the SO4:Zr molar ratio must be up than 0.125. The higher this ratio, the higher is the activity of these solids. It appears that highly polymerized entities are more active than individual sulfated polycations. The isopropanol dehydration to propene as well as the isomerization of n-hexane seems to be related to the number and the strength of Bronsted acidity. (C) 2004 Published by Elsevier B.V

Assessing hydrological vulnerability to future droughts in a Mediterranean watershed : combined indices-based and distributed modeling approaches

Understanding the spatiotemporal distribution of future droughts is essential for effective water resource management, especially in the Mediterranean region where water resources are expected to be scarcer in the future. In this study, we combined meteorological and hydrological drought indices with the Soil and Water Assessment Tool (SWAT) model to predict future dry years during two periods (2035-2050and 2085-2100) in a typical Mediterranean watershed in Northern Morocco, namely, Bouregreg watershed. The developed methodology was then used to evaluate drought impact on annual water yields and to identify the most vulnerable sub-basins within the study watershed. Two emission scenarios (RCP4.5 and RCP8.5) of a downscaled global circulation model were used to force the calibrated SWAT model. Results indicated that Bouregreg watershed will experience several dry years with higher frequency especially at the end of current century. Significant decreases of annual water yields were simulated during dry years, ranging from -45.6% to -76.7% under RCP4.5, and from -66.7% to -95.6% under RCP8.5, compared to baseline. Overall, hydrologic systems in sub-basins under the ocean or high-altitude influence appear to be more resilient to drought. The combination of drought indices and the semi-distributed model offer a comprehensive tool to understand potential future droughts in Bouregreg watershed

Acidic properties of a clay prepared from the reaction of zirconyl chloride solution containing sulfate ions with montmorillonite

Sulfated zirconium oxyhydroxide clays were prepared by adding ammonium sulfate to the intercalation solution. The main parameter controlled in this study was the SO4:Zr ratio in solution. The characterization of the catalysts, their acidic properties and catalytic activities were examined by N-2-BET adsorption, chemical analysis, adsorption-desorption of basic molecules and conversion of n-hexane and isopropanol. Two different types of SO4-Zr polycation binding were proposed and related with the acidic properties of these solids. To enhance the acidity of the sulfated zirconium oxyhydroxide clay, the SO4:Zr molar ratio must be higher than 0.125. The higher this ratio, the higher is the activity of these solids. It appears that polymerised entities are more active than individual sulfated polycations. Isopropanol dehydration to propene as well as isomerization of n-hexane seem to be related to the number and strength of Bronsted acid sites. (C) 2003 Elsevier B.V. All rights reserved

Assessing hydrological vulnerability to future droughts in a Mediterranean watershed: combined indices-based and distributed modeling approaches

Understanding the spatiotemporal distribution of future droughts is essential for effective water resource management, especially in the Mediterranean region where water resources are expected to be scarcer in the future. In this study, we combined meteorological and hydrological drought indices with the Soil and Water Assessment Tool (SWAT) model to predict future dry years during two periods (2035–2050and 2085–2100) in a typical Mediterranean watershed in Northern Morocco, namely, Bouregreg watershed. The developed methodology was then used to evaluate drought impact on annual water yields and to identify the most vulnerable sub-basins within the study watershed. Two emission scenarios (RCP4.5 and RCP8.5) of a downscaled global circulation model were used to force the calibrated SWAT model. Results indicated that Bouregreg watershed will experience several dry years with higher frequency especially at the end of current century. Significant decreases of annual water yields were simulated during dry years, ranging from -45.6% to -76.7% under RCP4.5, and from -66.7% to -95.6% under RCP8.5, compared to baseline. Overall, hydrologic systems in sub-basins under the ocean or high-altitude influence appear to be more resilient to drought. The combination of drought indices and the semi-distributed model offer a comprehensive tool to understand potential future droughts in Bouregreg watershed

Design of TiO2 nanomaterials for photocatalytic applications: organic pollutants degradation and microorganisms inactivation

SSCI-VIDE+CARE:ECI2D+GBE:CGUInternational audienceNon