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排序方式: 共有253条查询结果,搜索用时 212 毫秒
211.
Mohsen Jalali 《Environmental Earth Sciences》2013,68(7):2041-2049
The chemistry of soil solutions can be altered by human activities, due to the intense agricultural and husbandry, leading to leaching of nutrients and subsequently elevating ground water levels. Multivariate statistical and inverse geochemical modeling techniques were used to determine the main factors controlling soil solution chemistry of calcareous soils. In this research, a total of 21 calcareous soils was characterized and assessed for soil solution using soil column. The major cations in the studied soil solutions were in the decreasing order as Ca2+ > Mg2+ > Na+ > K+. The anions were also arranged in decreasing order as HCO $ _{3}^{ - } $ > Cl $ ^{ - } $ > SO $ _{4}^{2 - } $ > NO $ _{3}^{ - } $ . Concentrations of NO $ _{3}^{ - } $ , P, and K+ in soil solutions were in the range of 6.8–307.5 mg l?1 (mean 63.2 mg l?1), 5.0–10.4 mg l?1 (mean 5.9 mg l?1), and 2.8–54.6 mg l?1 (mean 11.3 mg l?1), respectively. Results suggest that the concentration of P in the soil solutions could be primarily controlled by the solubility of dicalcium phosphate dihydrate and dicalcium phosphate. Interactions between soil properties and observed solubility of nutrients were described, and put into empirical multivariate formulations. Obtained equations contained electrical conductivity (EC) as a key factor in determining nutrients solubility. Inverse geochemical modeling of soil solution using PHREEQC indicates the dissolution of calcite, anhydrite, halite, CO2 (g), N2 (g), and hydroxyapatite, and precipitation of sulfur. Cation exchange between Ca2+, Mg2+, K+ and Na+ occurred with Mg2+ and K+ into the solution, and Ca2+ and Na+ out of the solution. Determination of soil solution will improve soil management in the area, and preventing groundwater deterioration. 相似文献
212.
Mapping of the soil texture using geostatistical method (a case study of the Shahrekord plain, central Iran) 总被引:1,自引:0,他引:1
Yaser Safari Isa Esfandiarpour Boroujeni Ardavan Kamali Mohammad Hassan Salehi Mohsen Bagheri Bodaghabadi 《Arabian Journal of Geosciences》2013,6(9):3331-3339
Soil texture is a key variable that reflect a number of soil properties such as soil permeability, water holding capacity, nutrient storage and availability, and soil erosion. The main objective of this study was to produce the kriged maps of soils of the Shahrekord region, central Iran. One hundred four soil samples were collected on a 375-m2 sampling grid from the depths of 0–30, 30–60, and 60–100 centimeter, and their particle sizes were determined using hydrometer method. The results showed a moderately spatial correlation in the soil particles among sampling soil layers and across the study area. Moreover, increasing clay and therewith observation of heavier soil textures is evident from surface to subsurface layers of the soils in the studied area due to rainfall and/or irrigation agriculture. These findings indicated that study of the soil texture variation with depth can be used as a clue for site-specific management and precision agriculture. Moreover, we suggest further analysis by using other data layers like topographical parameters, land use, parent material, soil erosion, and any other information which might influence the spatial distribution of soil texture. 相似文献
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Soodabeh Khalili Ali Asghar Ghoreyshi Mohsen Jahanshahi Kasra Pirzadeh 《洁净——土壤、空气、水》2013,41(10):939-948
In this study, crude multi‐walled carbon nanotubes (MWCNT) was functionalized by a two‐step process; first using strong mixed acids (H2SO4/HNO3) and then treatment with 1,3‐phenylenediamine (mPDA). The equilibrium adsorption of CO2 on pristine MWCNT and amine functionalized MWCNT (MWCNT‐NH2) were investigated. Experiments were preformed via application of volumetric method in a dual sorption vessel at temperature range of 298–318 K and pressures up to 40 bars. The results obtained indicated that the equilibrium uptake of CO2 increased after functionalizing of MWCNT. The increase in CO2 capture by MWCNT‐NH2 was attributed to the existence of great affinity between CO2 molecules and amine sites on this adsorbent at low pressures. The experimental data were analyzed by means of Freundlich and Langmuir adsorption isotherm models. The data obtained revealed a fast kinetics for the adsorption of CO2 in which most of adsorption occurred at initial period of adsorption experiments. This renders MWCNT as a suitable adsorbent for practical applications. Values of isosteric heat of adsorption were evaluated based on Clausius–Clapeyron equation. The results demonstrated that both chemisorption and physisorption played important role in CO2 adsorption on MWCNT‐NH2, whereas the physisorption process was dominant for CO2 adsorption on MWCNT. 相似文献
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One of the most important factors in optimized design of non-yielding retaining walls like basement walls and bridge abutments is to determine the exact variation of earth pressure acting on such walls. In this paper, the distribution of at rest earth pressure behind a laboratory model of a fixed and rigid retaining wall with a cohesionless dry backfill is measured under the effect of static and repeated loads. The same conditions of the experimental model are then simulated numerically with a two-dimensional finite-difference analysis computer code. For the purpose of model verification, the results of numerical model are compared to the results of the experimental model, which is similar in geometrical and geomechanical properties. Cyclic surcharges with different amplitudes and frequencies are applied in different distances from the wall, and the earth pressure distribution, the resultant force, and its point of application are investigated. The effect of soil and loading parameters on the at rest earth pressure is also evaluated, and a parametric study has been carried out. The results of model show a significant increase in the earth pressure due to cyclic loading compared to static loading, especially in the initial cycles of loading. It indicates that the effect of cycling nature of loading should be essentially taken into account in the design of retaining walls. 相似文献
220.
Sedaghati Parshan Gerami Mohsen Naderpour Hosein 《Bulletin of Earthquake Engineering》2022,20(11):6267-6305
Bulletin of Earthquake Engineering - Since post-mainshock events following a major earthquake are likely to occur, it is imperative to have an understanding of the functionality status of... 相似文献