Environmental, Synthetic, and Materials Applications of Molybdenum Trioxide

The objective of this research was the development of new methods for the synthesis of metal molybdates using molybdenum trioxide. The latter is also used to remediate heavy metal-contaminated water. In the case of uranium, it was found that MoO3 could absorb up to 165% by weight of uranium when reacted with uranyl acetate. The insoluble product was identified as the mineral umohoite [(UO2)MoO4(H2O)](H2O). A regeneration process was successfully achieved by treating the product with an aqueous solution of 15% ammonium hydroxide. The recovery of molybdenum oxide was 98.9% by weight and the efficiency of separation of uranium from umohoite was 96.1% by weight. When applying the same technique to different transition metals and alkaline-earth metals, the products obtained after heating at moderate temperatures were in the form of MMoO4 (M= Mn, Co, Zn, Cd, Pd, Ca, Sr, Ba). The latter could be used as heterogeneous catalysts for several oxidation processes. The method was further extended to synthesize lanthanide molybdates. In the case of lanthanum, a mixed metal oxyacetate was obtained that converted to the cubic form of La2Mo2O9 (an oxide conductor) upon heating to 550 �C. On the other hand, the reaction of gadolinium acetate with molybdenum oxide yielded hydrous mixed metal oxides that converted to the ferroelectric Gd2(MoO4)3 at higher temperature. Molybdenum trioxide was determined to be an excellent tool for removal of heavy metals from water. The process involves the formation of mixed metal molybdates, which play significant role in many areas of chemistry, physics and material sciences.Chemistry Departmen

Assessing different irrigation innovations for better climate resilience of olive farming systems in Morocco

Drought and water crises jeopardize olive systems (1.1 Mha), a climate adaptation focus of the Green Morocco Plan. This case study with Tensift Basin stakeholders will inform what/where new irrigation innovations could reduce the water footprint of olive systems without economic tradeoffs. Two experiments were established in 2022 near Marrakech (Agdal domaine and on-farm) to test surface and sub-surface drip and deficit irrigation practices. Through hybrid model frameworks, a Climate-Smart Systemic Solutions and Scaling (C4S) yield gap prediction subtool was co-developed to test different irrigation scenarios for olive farms, to know if a combination of irrigation innovation and soil fertilization practices could be a good water and climate resilience option for olive farms. A PhD thesis supervised by Mohammed VI Polytechnic University (UM6P) and Cadi Ayyad University (UCA) began at the end of 2022 on the co-development of appropriate cross-scale fertirrigation guidance resulting from this work

Calibration and validation of the STICS crop model for managing wheat irrigation in the semi-arid Marrakech/Al Haouz Plain

In the first part of this work, the shoot growth module and grain yield of the STICS crop model were calibrated and validated by using field data which was collected from irrigated winter wheat fields in the Haouz plain near Marrakech. The calibration was performed on the thermal units between the four phenological stages that control the dynamics of leaf area index and the thermal unit between emergence and the beginning of grain filling. The plant phenology was calibrated for three fields monitored during the 2002/03 season. Evaluation of the grain yields and the temporal evolution of leaf area index were done for six validation fields during 2003/04. The results showed the significant accuracy of the model in simulating these variables, and also indicated that the plants mainly suffered from lack of nitrogen. The results in the second part show the potential of crop modeling to schedule irrigation water, on the assumption that the plants were growing under optimal conditions of fertilization. In this case, the model was used to manage the time of irrigation according to a threshold for water deficit. Various simulations displayed logical trends in the relationship between the grain yield and both the amount and timing of irrigation water. These results were finally compared with those obtained from real irrigation practices. For the particular climate of 2003/04, the comparison showed that 70 mm and 40 mm of water could be saved in case of early and late sowing, respectively

The red edge in arid region vegetation: 340-1060 nm spectra

The remote sensing study of vegetated regions of the world has typically been focused on the use of broad-band vegetation indices such as NDVI. Various modifications of these indices have been developed in attempts to minimize the effect of soil background, e.g., SAVI, or to reduce the effect of the atmosphere, e.g., ARVI. Most of these indices depend on the so-called 'red edge,' the sharp transition between the strong absorption of chlorophyll pigment in visible wavelengths and the strong scattering in the near-infrared from the cellular structure of leaves. These broadband indices tend to become highly inaccurate as the green canopy cover becomes sparse. The advent of high spectral resolution remote sensing instrument such as the Airborne Visible and Infrared Imaging Spectrometer (AVIRIS) has allowed the detection of narrow spectral features in vegetation and there are reports of detection of the red edge even for pixels with very low levels of green vegetation cover by Vane et al. and Elvidge et al., and to characterize algal biomass in coastal areas. Spectral mixing approaches similar to those of Smith et al. can be extended into the high spectral resolution domain allowing for the analysis of more endmembers, and potentially, discrimination between material with narrow spectral differences. Vegetation in arid regions tends to be sparse, often with small leaves such as the creosote bush. Many types of arid region vegetation spend much of the year with their leaves in a senescent state, i.e., yellow, with lowered chlorophyll pigmentation. The sparseness of the leaves of many arid region plants has the dual effect of lowering the green leaf area which can be observed and of allowing more of the sub-shrub soil to be visible which further complicates the spectrum of a region covered with arid region vegetation. Elvidge examined the spectral characteristics of dry plant materials showing significant differences in the region of the red edge and the diagnostic ligno-cellulose absorptions at 2090 nm and 2300 nm. Ray et al. detected absorption at 2100 nm in AVIRIS spectra of an abandoned field known to be covered by a great deal of dead plant litter. In order to better study arid region vegetation remote sensing data, it is necessary to better characterize the reflectance spectra of in situ, living, arid region plants

Comparison of large aperture scintillometer and eddy covariance measurements: Can thermal infrared data be used to capture footprint-induced differences?

Eddy covariance (EC) and large aperture scintillometer (LAS) measurements were collected over an irrigated olive orchard near Marrakech, Morocco. The tall, sparse vegetation in the experimental site was relatively homogeneous, but during irrigation events spatial variability in soil humidity was large. This heterogeneity caused large differences between the source area characteristics of the EC system and the LAS, resulting in a large scatter when comparing sensible heat fluxes obtained from LAS and EC. Radiative surface temperatures were retrieved from thermal infrared satellite images from the Landsat Enhanced Thematical Mapper and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellites. Using these images in combination with an analytical footprint model, footprint-weighted radiative surface temperatures for the footprints of the LAS and the EC system were calculated. Comparisons between the difference in measured sensible heat fluxes and the difference in footprint-weighted radiative surface temperature showed that for differences between the footprint-weighted radiative surface temperatures larger than 0.5 K, correlations with the difference in measured sensible heat flux were good. It was found that radiative surface temperatures, obtained from thermal infrared satellite imagery, can provide a good indication of the spatial variability of soil humidity, and can be used to identify differences between LAS and EC measurements of sensible heat fluxes resulting from this variability

Recent Climate Change Adaptation Strategies in the Sahel: A Critical Review

Climate change adaptation continues to be central on the agenda of most African countries. Current understanding of the state of adaptation is limited in Africa. The Sahel is selected because of persistent declines in precipitation and rising temperatures. Here, we examine the status of adaptation actions across the Sahel by reviewing the primary peer review literature. A total of 70 peer review papers that document 414 discrete adaptations provide a snapshot of adaptations developed between 1975 and 2020. From a country-to-country perspective, Kenya has the highest number of reported adaptation actions (75 or 18.1%). From a regional standpoint, West Africa recorded about 261 or 18.1% of all adaptation actions reported. Income diversification of livelihoods, and water harnessing were reported as the most used adaptation actions in the Sahel. Based on categories, technically based adaptation actions are the most used options. The period 2008–2016 registered 65.2% of all adaptations. 98% of adaptation actions are reported to be driven by climate while non-climatic drivers account for 95% of adaptation actions. The findings presented here are proxies of climate change adaptation; some relevant information might be found in gray literature which not used because gray literature is less standardized because it is not subject to peer review