Mineralogical composition of khamasin wind dust at Assiut, Eygpt

The present study investigated the mineralogical composition of the deposited dust from Khamasin wind on the agricultural soils at Assiut city through April 2008 and 2009. Five sites were chosen between the fringes of eastern and western deserts throughout the Nile valley. Wood boxes [dimensions of 1xlm] were put in the selected sites and precipitated dust was collected from each box after the finish of Khamasin storms in the two years. The quantity, pH and EC were determined for the collected Khamasin dust. The mineral particles of these dusts were examined by the scanning electron microscope [SEM] and the X-ray analysis. The obtained results revealed some variation in the dust quantity of Khamasin wind in the year of 2008 and 2009. The quantity of the collected bulk samples of the Khamasin dust varied from site to another in both 2008 and 2009 years. The highest amounts in both years are recorded in the sites of the eastern side of the Nile valley that faraway from the western desert where the Khamasin wind come. The mean values of dust EC and pH were low and similar in both years of 2008 and 2009. The Scanning electron microscope photomicrographs showed that the grain sizes of Khamasin dust in the sites located in the interference zone of Nile valley with the eastern desert were finer than those in site located in the western side of the Nile river. Generally, relatively large angular to subangular grains, larger amount of very Fine grains with more oblate particle and spherical particles with differences in size as well as particles with irregular shapes in Khamasin dust of 2008 and 2009 years. Semi-quantitative measurements of the identified minerals in the Khamasin dust of 2008 year have shown the order of quartz >k-feldspar>calcite> magnetite >epidote> anhydrite > garnet > augite> tourmaline > zircon > ilmenite > plagioclase > goethite > actinolite > hematite. However, the minerals in the Khamasin dust of 2009 year could be ordered as quartz >k-feldspar>calcite>epidote> magnetite > tourmaline > anhydrite > augite > plagioclase >Imenite>rutile> hematite > garnet >actinolite. There was no general trend for distribution of these minerals throughout the studied sites. From a qualitative point of view, most of the sites have the same mineralogical composition. Comparison of the mineralogical compositions of mineral dusts at the five sites, revealed certain quantitative differences

Estimation and signification of cation exchange capacity of cheliff saline soils [Algeria] for physical properties

Measurements of the cation exchange capacity [CEC] show significant soil properties, in particular its ability to retain the cations because of their mobility in the soil. Thirteen soil samples rich in electrolytes of the Cheliff plain [Algeria] were analyzed in order to measure their CEG and to draw up the existing relationship between texture, organic

atter content and pH. In calcareous soils, the CEC values are always higher than those measured at pH 7. Regression equations using the percentages of organic carbon and clay as independent variables would make it possible to estimate 90% of the variability of the CEC measured in the ammonium acetate buffered at pH 7 and 89% of the variability for that measured at the pH of the soil These percentages are particularly useful due to the fact that they make it possible to estimate the CEC of the soil according to the pH only starting from the organic matter and texture. The correlations between the salinity indices, the parameters of the saline phase and the physical properties, show that the cobalt hexamine method makes it possible to characterize the soil of this plain with more precision than the Metson method. It constitutes a means for following up the chemical quality of the soil. The Metson method makes it possible to approach the reactivity of the soil in relation with the geometry of the components. The measurement of the CEC at pH 7 makes it possible to envisage the water content at the permanent wilting point of the plants. Finally, it is noticed that a sodization of the adsorbing compound, which consequently generates a reduction in the structural stability and a reduction in the infiltration always leads to the salinity in these soil types