The thermoluminescence (TL) of heated amorphous ZrO2, doped by Ti, Th, U, Nb, Dy, excited by 253.7 nm or X‐radiation is investigated. Six main peaks are observed at 100, 135, 190, 245, 285, and 385 K and their activation energies determined by four methods. It is shown that most traps obey Curie's model, and that the tetragonal form, which coexists with the monoclinic form, is related to the 245 K peak. The analysis of various TL emission spectra indicates that the emission centres are localized and are connected with Ti3+ surrounded by six oxygens. A centre model is discussed in terms of configuration coordinate curves.

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Since the construction of the anti-salting Diama dam, a ressumption of aeolian deflation is observed in the Senegal delta, and particularly in the Diawling National Park. It results in the formation of many clay dunes with high salt concentrations. The soft powdery structure observed on the soil surface, affected by aeolian deflation is due to rapid salt crystallisation. In order to identify the mineralogy of the salt involved in this environment, the chemistry of soil and groundwater was studied along a transect from a pan to the associated clay dune. Equilibria computation and field and SEM observations indicated that the changes observed in the chemical facies of the solution were due to the following precipitation sequence: calcite > gypsum > halite. A progressive but significant fixing of Na + onto the clay particles was observed. The calcite deposition in the soil was limited by exhibition of the potential acidity arising from the former mangrove site soils. It resulted in high equilibrating pCO2. This study provided to test a new extension to the Debye-Hückel law for concentrated chlorurated sodic waters. The relationship between chloride amounts and residual alkalinity concept confirmed that calcite and gypsum formation, and the exchanges between Na and Ca are the main phenomena responsible for the changes observed in the soil solution (r² = 0.99).

Synthèses hydrothermales de zirconosilicates de sodium entre 300° C et 700° C, à une pression constante de 700 bars : catapléite, elpidite, vlasovite, keldyshite, Na₂ZrSiO₅, Na₁₄Zr₂Si₁₀O₃₁ ; et de deux nouvelles phases. Études morphologiques et radiocristallographiques. Corrélations pétrogénétiques.

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