Soil dispersion is a phenomenon in which soil particles become afloat when they are exposed to water, and are carried away by the force of seepage. In spite of that soil dispersion is due to its chemical composition, the results obtained from the chemical methods, especially from the most widely used, Sherard method does not match with the results of well-known Pinhole test. This study tries to evaluate and modify the Sherard diagram for determination of dispersion potential of clayey soils. For this purpose, several natural soil samples were collected from different regions of Iran and some artificial soil samples were made by adding different percentages of four chemical agents, including sodium chloride, sodium carbonate, sodium sulfate, and sodium polyphosphate to a natural soil. The physical, chemical and index properties of all samples were determined and for determination of dispersion potential, the commonly used chemical test (Sherard method) and Pinhole test were employed. The results obtained from the tests showed that the Sherard chemical method which is solely based on the amount and type of the existing cations, is not able to determine soil dispersion correctly since the role of some anions, especially chloride is neglected. It was also found that among the existing anions in the soil, the chloride on the contrary to sodium acts as a flocculating factor. The results showed that by converting the vertical axis of the Sherard chart from sodium% to (sodium chloride)%, its conformity to the results of Pinhole tests increases considerably. 相似文献
The numerous non-sulfide zinc ore deposits were the historical basis for the development of zinc mining in Iran.They include the Mehdiabad,Irankouh and Angouran world-class deposits,as well as the Zarigan and Haft-har deposits.These deposits were formed by supergene oxidation of primary sulfide minerals during the complex interplay of tectonic uplift,karst development,changes in the level of the water table,and weathering.Zn(Pb)carbonates,Zn-hydrosilicates and associated hydrated phases directly replace the primary ore bodies or fill cavities along fractures related to uplift tectonics.Direct replacement of primary sulfides is accompanied by distal precipitation of zinc non-sulfide minerals in cavities or internal sediments filling.The mineralogy of the non-sulfide mineralization in all six deposits is generally complex and consists of smithsonite,hydrozincite,and hemimorphite as the main economic minerals,accompanied by iron and manganese oxy-hydroxides and residual clays.Commonly,non-sulfide minerals in these deposits consist of two types of ore:red zinc ore(RZO),rich in Zn,Fe,Pb-(As)and white zinc ore(WZO),typically with very high zinc grades but low concentrations of iron and lead.Typical minerals of the RZO are Fe-oxyhydroxides,goethite,hematite,hemimorphite,smithsonite and/or hydrozincite and cerussite.Common minerals of the WZO are smithsonite or hydrozincite and only minor amounts of Fe-oxyhydroxides and hemimorphite. 相似文献
In this study, the seismic stability of arch dam abutments is investigated within the framework of the probabilistic method. A large concrete arch dam is considered with six wedges for each abutment. The seismic safety of the dam abutments is studied with quasi-static analysis for different hazard levels. The Londe limit equilibrium method is utilized to calculate the stability of the wedges in the abutments. Since the finite element method is time-consuming, the neural network is used as an alt... 相似文献
Iranian nesting populations of the critically endangered hawksbill turtle(Eretmochelys imbricate) are some of the most important in the Indian Ocean. In this study, four of the most important hawksbill nesting grounds in the Persian Gulf, situated within three Iranian marine protected areas, were surveyed during nesting season,including Nakhiloo, Ommolgorm and Kharko Islands and the mainland beaches of the Naiband Marine-Coastal National Park(NMCNP). We present GIS maps of these key nesting grounds and describe sand texture of key nesting zones, along with conservation recommendations. About 9.2(28.3%) out of 32.5 km of all shores surveyed in this study were used by nesting hawksbill turtles follows: Nakhiloo: 1.4 km(52% of potential nesting area);Ommolgorm: 1.94 km(40%); Kharko: 3.4 km(28%), and NMCNP: 2.46 km(18.9%). The average nesting density was calculated as 131 nests/km at Nakhiloo, 76 nests/km at Ommolgorm, 7 nests/km at Kharko, and 15 nests per km at NMCNP. Highest nesting density was observed in Nakhiloo and Ommolgorm. It is thought that high hawksbill nesting density in these islands seems likely a result of limiting adequate nesting shores rather than the size of population, and also low density in Kharko and NMCNP more related to past and current pressures and low population density. With the exception of Ommolgorm Island, sands at the nesting grounds were well sorted.Grain size indicated that female hawksbill turtles in the Iranian Persian Gulf nest in sands that are generally mixed, with mean grain size ranging from coarse sands(0.4Φ;~0.5–1 mm) to fine sands(2Φ;~0.25 mm). We provide and discuss conservation recommendations and suggestions for future. 相似文献
Delineation of facies in the subsurface and quantification of uncertainty in their boundaries are significant steps in mineral resource evaluation and reservoir modeling, which impact downstream analyses of a mining or petroleum project. This paper investigates the ability of nonparametric geostatistical simulation algorithms (sequential indicator, single normal equation and filter-based simulation) to construct realizations that reproduce some expected statistical and spatial features, namely facies proportions, boundary regularity, contact relationships and spatial correlation structure, as well as the expected fluctuations of these features across the realizations. The investigation is held through a synthetic case study and a real case study, in which a pluri-Gaussian model is considered as the reference for comparing the simulation results. Sequential indicator simulation and single normal equation simulation based on over-restricted neighborhood implementations yield the poorest results, followed by filter-based simulation, whereas single normal equation simulation with a large neighborhood implementation provides results that are closest to the reference pluri-Gaussian model. However, some biases and inaccurate fluctuations in the realization statistics (facies proportions, indicator direct and cross-variograms) still arise, which can be explained by the use of a single finite-size training image to construct the realizations.
This study was conducted to evaluate the weathering intensity of the major soils developed on igneous rocks in semiarid region of northwestern Iran.Eight parent materials were selected including monzodiorite,alkali granite,granodiorite,syenite,pyroxene diorite,hornblende andesite,pyroxene andesite,and dacite.Representative soil profiles were described and soil samples were collected and analyzed for selected chemical and physical properties and total concentrations of major elements and Zr,V,Ti and Y.Bulk densities as well as Ti,Zr and V concentrations were used to estimate the strain factors and mass balance equations were used to quantify the net result of pedogenic weathering,i.e.elemental loss and gain.The results of clay content and pedogenic iron variability as well as index of compositional variability(ICV),chemical index of alteration(CIA) and,A-CN-K and MFW ternary plots showed that the soils developed on volcanic rocks(hornblende andesite> pyroxene andesite> dacite) were more weathered than those on the plutonic parent rocks(alkali granite,granodiorite,monzodiorite,syenite,pyroxene diorite).The results of mass balance calculations based on the strain factors revealed that the Ca and Na depleted during weathering progress mostly from plagioclase grains.In the semiarid regions Ca is precipitated as pedogenic calcite in the soil horizons.K and Mg depletion is less than Ca and Na especially in the profiles on the hornblende andesite with the highest clay and LOI content.The results of this study clearly suggest that the behavior of K and Mg during the weathering cannot only be explained by the disintegration of the primary minerals,since they are fixed on the secondary clay minerals.Iron did not change in the soils compared to the parent material and was precipitated as the pedogenic iron and conserved in the soil horizons.Overall,the results on the weathering indicators and major elements mass balance enrichment/depletion in the study area confirmed that the soil profiles developed on volcanic rocks are more weathered than those on the plutonic igneous rocks. 相似文献
The mixtures of dried sewage sludge (DSS) and sewage sludge ash were studied for removal of acid red 119 (AR119) dye as a new, more environmental friendly, and low cost adsorbent. For this purpose, response surface methodology was applied to optimize the dye removal efficiency and turbidity of treated dye solutions as two individual responses. Results revealed that an optimum condition under specified constraints (dye removal efficiency >95% and turbidity <50 NTU) was obtained at a contact time of 60 min, 40 wt% DSS in the mixture, an initial pH of 6, and an initial dye concentration of 200 mg dye/L in distilled water. Under the optimal condition, dye removal efficiency of 94.98% and effluent turbidity of 24.9 NTU was observed. In further studies, at optimum condition, the effect of some additives on adsorption process and desorption/reusability of adsorbent was investigated. It was observed that removal efficiency was significantly decreased to 83.76% when a simulated dye wastewater (containing the selected dye, acetic acid, and Glauber's salt dissolved in tap water) was used. Desorption studies revealed that AR119 dye could be well removed from dye‐loaded adsorbent by 0.3 M NaOH solution. 相似文献
A stable extractor of metal ions was synthesized through azo linking of o‐hydroxybenzamide (HBAM) with Amberlite XAD‐4 (AXAD‐4) and was characterized by elemental analyses, IR spectral, and thermal studies. Its water regain value and hydrogen ion capacity were found to be 12.93 and 7.68 mmol g?1, respectively. The optimum pH range (with the half‐loading time [min], t1/2) for Cu(II), Cr(III), Ni(II), Co(II), Zn(II), and Pb(II) ions were 2.0–4.0 (5.5), 2.0–4.0 (7.0), 2.0–4.0 (8.0), 4.0–6.0 (9.0), 4.0–6.0 (12.0), and 2.0–4.0 (15.0), respectively. Comparison of breakthrough and overall capacities of the metals ascertains the high degree of column utilization (>70%). The overall sorption capacities for Cu(II), Cr(III), Ni(II), Co(II), Zn(II), and Pb(II) ions were found to be 0.29, 0.22, 0.20, 0.16, 0.13, and 0.11 mmol g?1 with the corresponding preconcentration factor of 400, 380, 380, 360, 320, and 320, respectively. The limit of preconcentration was in the range of 5.0–6.3 ng mL?1. The detection limit for Cu(II), Cr(III), Ni(II), Co(II), Zn(II), and Pb(II) were found to be 0.39, 0.49, 0.42, 0.59, 0.71, and 1.10 ng mL?1, respectively. The AXAD‐4‐HBAM has been successfully applied for the analysis of natural water, multivitamin formulation, infant milk substitute, hydrogenated oil, urine, and fish. 相似文献