نتایج جستجو برای: loess soils
تعداد نتایج: 52082 فیلتر نتایج به سال:
by MARISSA C. MERKER, M.S.C.E. Washington State University August 2010 Chair: Richard J. Watts Persulfate is a promising in situ chemical oxidation treatment (ISCO) for the remediation of low-permeability strata because it is more stable in the subsurface and can rapidly degrade recalcitrant contaminants compared to other technologies. ISCO technologies include catalyzed hydrogen peroxide propa...
In many seismically active regions of Central Asia, weak water-saturated sandy and silty-clayed soils are widely spread; industrial and civil facilities of various purposes are built and operated on them. The operating experience, macro-seismic examinations of earthquake consequences and the results of laboratory and field investigations show that the strength and deformational characteristics ...
Loess/soil sequences have been proven to be excellent paleoclimate indicators. Large areas of northern Iran are covered by loess deposits which provide a good condition to carry out research on paleoclimate, paleosols and discontinuities. The objectives of this research were to identify clay minerals of soil-loess sequences, to determine the role of climate change in clay mineral transform...
The occurrence of palygorskite and its formation conditions in soils and sediments were studied along a transect covering granitic hilly lands to marly hilly lands in southern Mashhad. Based on formation conditions, amount and morphology, three kinds of palygorskite including high-amount palygorskite with long fibers in gypsiferous marl and basal part of deep loess deposits with high salinity, ...
In years 2007-2008 field experiment with spring wheat was conducted on the parcels (14 m ) with 2m deep concrete walls, filled with six different soils. The goal of this experiment was to evaluate the influence of soil quality on yield and technological properties of spring wheat varieties. The results of the conducted experiment showed that the highest level of spring wheat yielding were obtai...
On the basis of plastic bounding surface model, the damage theory for structured soils and unsaturated soil mechanics, an elastoplastic model for unsaturated loessic soils under cyclic loading has been elaborated. Firstly, the description of bond degradation in a damage framework is given, linking the damage of soil’s structure to the accumulated strain. The Barcelona Basic Model (BBM) was cons...
Biological soil covers such as lichens have critical roles in soil stability and prevention of erosion. In order to study the effect of lichen biological covers on aggregate stability and soil conservation, loess hills covered with lichen and uncovered ones were selected in Northern Golestan Province. Five samples were taken from the depth 0 to 5 cm of both two areas for physico-chemical analys...
This study was aimed to identify optimal indicators for microtopography-oriented soil quality assessment. Twenty-two soil physicochemical and biological parameters were investigated at 93 sampling points in five different microtopographic units in semiarid regions of the Loess Plateau, where the principal functions of eroded agriculture soils are related to productivity and anti-erosion ability...
The response of soil properties to vegetation types is still not well understood and the relationship between vegetation types and soil properties has not been quantified in highland grasslands. A field experiment was conducted in highland grassland of the Loess Plateau in China to study the distribution of soil properties under different vegetation. 22 plant communities totaling 17 species tha...
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