Fluctuations in soil moisture create drying-rewetting events affecting the activity of microorganisms. Microbial responses to drying-rewetting are mostly studied in soils that are air-dried before rewetting. Upon rewetting, two patterns of bacterial growth have been observed. In the Type 1 pattern, bacterial growth rates increase immediately in a linear fashion. In the Type 2 pattern, bacterial...

In order to sustainable use of rangelands, it is necessary to recognize water, soil, and vegetation cover and analyze their relationships. Physical and chemical properties of soil are effective in distribution of plant species in local area. To determine the effects of some soil properties on species distribution of Eurotia ceratoides and Stipa barbata in Baghedar summer region of Bafgh, three ...

If life ever existed, or still exists, on Mars, its record is likely to be found in minerals formed by, or in association with, microorganisms. An important concept regarding interpretation of the mineralogical record for evidence of life is that, broadly defined, life perturbs disequilibria that arise due to kinetic barriers and can impart unexpected structure to an abiotic system. Many featur...

considerable information exists in the literature showing that expansive layer silicates are not the only clay minerals present in vertisols. however, the presence of a very high clay content dominated by fine clay, regardless of the clay type, together with the wetting and drying cycle in the soil can also produce a high shrink-swell potential. we studied some vertisols with diverse parent mat...

Introduction: In the study presented here, a technique based on the wavelet transform and described in the accompanying abstract ([1]) is applied to the nearinfrared spectra of Phobos obtained by ISM in 1989 from the Phobos-2 spacecraft. Small mineralogical variations are observed across the red, optically altered, unit of Phobos. The mineralogical composition appears to comprise olivine in the...

The chemicalmineralogical composition of the sand fractions of mortars found in Roman villas dating from the 1 st century A.C. located in Northern Italy has been investigated by optical microscopy, scanning electron microscopy plus energy dispersive spectroscopy microanalysis and x-ray diffractometry. The petrographic results on the mortar samples have been compared with mineralogical data avai...

Ice types, albedos and impurity content are characterized for the ablation zone of the Greenland ice sheet in Kronprinz Christians Land (808N, 248W). Along this ice margin the width of the ablation zone is only about 8 km. The emergence and melting of old ice in the ablation zone creates a surface layer of dust that was originally deposited with snowfall high on the ice sheet. This debris cover...