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Bacterial activity in the near-field environment of radioactive waste disposal facilities in deep argillaceous rocks is currently under investigation. Bacterial development could be enhanced by the availability of low-molecular-weight organic acids (LMWOA) dissolved in the pore water of clayey rocks. This study firstly aimed at isolating and characterizing the LMWOA of the Toarcian argillite from the Tournemire Underground Research Laboratory (France, Aveyron). It also aimed at assessing the disturbing effects that could be induced by a disposal facility on the type and release of LMWOA (exposure to oxygen, alkaline pH, temperature increase). Under the experimental conditions investigated at 60 °C, the mean dissolved organic carbon (DOC) is about 15 mg L −1 with a LMWOA proportion of 35 %. The main LMWOA are composed of formate, fumarate, propionate, acetate, and lactate. DOC is mainly influenced by both temperature and pH increases, whereas the LMWOA type nature and release are more specifically affected by the exposure to oxygen. [ABSTRACT FROM AUTHOR]

Abstract: A geological study carried out in the Bomkoul area (Douala sub-basin, Cameroon) has revealed the presence of heterogeneous clayey materials on hills (80–120m altitude). The clay deposits are thick at the upper slope where sandstones and sandy-clay overlying clay layers, and thin at the middle and lower slopes where weathered clays overlying clay layers. Clayey materials identified are grey, dark-grey and mottled in color, with sandy-clay, clayey-silt, silty-clay and clay textures. Raw materials are mostly made up of fine particles ranging from 52 to 82% clay and silt in the mottled clayey material, 50 to 82% clay and silt in the dark-grey clayey material and 70 to 85% in the grey clayey material. Their chemical composition is characterized by silica (<70% SiO2), alumina (<32% Al2O3) and iron (1 to 16% Fe2O3). The main clay minerals are disorganized and poorly crystallized kaolinite and few smectite. The physical, mineralogical and geochemical properties of these materials presented and discussed in this work show that the clayey raw materials of the Bomkoul area have a good potential for pottery as well as brick, tile and soil sandstone manufacture. [Copyright &y& Elsevier]

Abstract: This Note presents an experimental study performed on expansive compacted loose and dense samples using osmotic oedometers. Several successive wetting and drying cycles were applied in a suction range between 0 and 8 MPa under different values of constant net vertical stress (15, 30, and 60 kPa). During the suction cycles, the dense samples showed cumulative swelling strains, while the loose samples showed volumetric shrinkage accumulation. At the end of the suction cycles, the volumetric strains converged to an equilibrium stage that indicated elastic behavior of the swelling soil for any further hydraulic variations. At this stage, the compression curves for the studied soil at the different imposed suctions (0, 2, and 8 MPa) converged towards the saturated state curve for the high applied vertical stresses. We defined this pressure as the saturation stress . The compression curves provided sufficient data to examine the soil mechanical behavior at the equilibrium stage. To cite this article: H. Nowamooz, F. Masrouri, C. R. Mecanique 337 (2009). [Copyright &y& Elsevier]

Abstract: Nodules of fossil resin, associated with lignitized woods, have been found, next to the pond of Berre, not far from Martigues, in the area of La Mède in clayey and sandy laguno-brackish formations of Santonian age. A FTIR study, using attenuated total reflexion with a diamond crystal, as well as the comparison with ambers and a copal of reference and with the FTIR data of the literature, has shown that this resin has a lesser maturity than Cretaceous ambers rather comparable to Baltic ambers of the Tertiary. This low maturity is confirmed by the analysis of the associated lignitized woods. However, the chemical structure of the amber of La Mède appears very different from that of Baltic ambers. To cite this article: M. Guiliano et al., C. R. Palevol 5 (2006) . [Copyright &y& Elsevier]

The symbiotic and competitive performances of two highly effective rhizobia nodulating French bean P. vulgaris were studied in silty loam and clayey soils. The experiments were carried out to address the performance of two rhizobia strains [CE3 and Ph. 163] and the mixture thereof with the two major cultivated bean cultivars in two soil types from major growing French bean areas in Egypt. Clay and silty loam soils from Menoufia and Ismailia respectively were planted with Bronco and Giza 6 phaseolus bean cultivars. The data obtained from this study indicated that rhizobial inoculation of Giza 6 cultivar in clayey soil showed a positive response to inoculation in terms of nodule numbers and dry weight. This response was also positive in dry matter and biomass accumulation by the plants. The inoculant of strain CE3 enhanced plant growth and N-uptake relative to Ph. 163. However, the mixed inoculant strains were not always as good as single strain inoculants. The competition for nodulation was assessed using two techniques namely fluorescent antibody testing (FA) and REP-PCR fingerprinting. The nodule occupancy by inoculant strain Ph. 163 in both soils occupied 30–40% and 38–50 of nodules of cultivar Bronco. The mixed inocula resulted in higher proportions of nodules containing CE3 in silty loam soil and Ph. 163 in clayey soil. The native rhizobia occupied at least 50% of the nodules on the Bronco cultivar. For cultivar Giza 6, the native rhizobia were more competitive with the inoculant strains. Therefore, we suggest using the studied strains as commercial inocula for phaseolus bean. To cite this article: H. Moawad et al., C. R. Biologies 327 (2004). [Copyright &y& Elsevier]