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Ahmad Zalooli David Martín Freire-Lista Mashalah Khamehchiyan Mohammad Reza Nikudel Rafael Fort Shahram Ghasemi 《Environmental Earth Sciences》2018,77(8):315
Durability of building stones is an important issue in sustainable development. Crystallization of soluble salts is recognized as one of the most destructive weathering agents of building stones. For this reason, durability of Ghaleh-khargushi rhyodacite and Gorid andesite from Iran was investigated against sodium sulfate crystallization aging test. Petrographic and physico-mechanical properties and pore size distribution of these stones were examined before and after the aging test. The characteristics of the microcracks were quantified with fluorescence-impregnated thin sections. Durability and physico-mechanical characteristics of Ghaleh-khargushi rhyodacite are mainly influenced by preferentially oriented preexisting microcracks. Stress induced by salt crystallization led to the widening of preexisting microcracks in Ghaleh-khargushi rhyodacite, as confirmed by the pore size distributions before and after the aging test. The preexisting microcracks of Gorid andesite were attributed to the mechanical stress induced by contraction of lava during cooling. The number of transcrystalline microcracks was significantly increased after the aging test. The degree of plagioclase microcracking was proportional to its size. Durability of the studied stones depends on initial physico-mechanical properties, pore size distribution, and orientation of microcracks. Initial effective porosity is found to be a good indicator of the stones’ durability. Salt crystallization resulted in an increase in the effective porosity with a parallel decrease in the wave velocities. Surface microroughness parameters increased with the development of salt crystallization-induced microcracking. Gorid andesite showed higher quality and durability than Ghaleh-khargushi rhyodacite. 相似文献
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The distribution of fractures and its dependence on lithology and petrophysical properties of rock in the Asmari Formation were examined using three wells data of one of the largest oil fields of southwestern Iran. Fractures were measured on cut cores. Mineral content and petrophysical data were obtained through thin section study and core plug measurement respectively. Influence of mineral composition and petrophysical property of rocks on fracture density was explored statistically. Increasing quartz (sand) and anhydrite content of rocks decrease and dolomite increases the threshold of fracture densities, however no significant relation was observed between calcite content of rock and fracture density. Increasing porosity and permeability of rock decrease the threshold of fracture density in some of the defined lithology groups. There are significant differences between the lithology groups in terms of fracture density, although the results in the three wells are not the same. In whole data, the highest fracture density can be observed in dolostone. Limestone and impure carbonates hold broader spaced fractures and sandstones display the least fracture density. The average fracture densities in the wells are strictly different. These differences are the result of the structural position of the wells and also the trend of the well and fractures. The distribution of fractures in most lithology groups can be explained by the function: , where F is relative frequency, D is fracture density and a, b, and c are constants. 相似文献
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Esmaeiloghli Saeid Tabatabaei Seyed Hassan Carranza Emmanuel John M. Hosseini Shahram Deville Yannick 《Natural Resources Research》2021,30(6):3925-3953
Natural Resources Research - This contribution proposes a spatially weighted factor analysis (SWFA) to recognize effectively the underlying mineralization-related feature(s) in geochemical signals.... 相似文献
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Hossein Tavallali Shahram Lalehparvar Abdo‐Reza Nekoei Maryam Ghane Jahromi Khodabakhsh Niknam 《洁净——土壤、空气、水》2012,40(6):640-647
A sensitive, reliable, and environmentally friendly method for simple separation and preconcentration of Ag(I) traces in aqueous samples is presented prior to their flame atomic absorption spectrometric determinations. At pH 7.0, Ag(I) was separated with 2‐(2‐methoxyphenyl)benzimidazole (MPBI) as a new complexing agent and floated after adding sodium dodecyl sulfate (SDS) as a foaming reagent. The floated layer was then dissolved in proper amount of concentrated nitric acid in methanol and introduced to the flame atomic absorption spectrometer (FAAS). The effects of pH, concentration of MPBI, type and amount of surfactant as the floating agent, type and amount of eluting agent, and influence of foreign ions on the recovery of the analyte ion were investigated. Also, using a nonlinear curve fitting method, the formation constant of 1.62 × 106 was obtained for Ag(I)–MPBI complex. The analytical curve was linear in the range of 1.8 × 10?7–1.7 × 10?6 mol/L for determination of Ag(I). The relative standard deviation (RSD; N = 10) corresponding to 0.7 × 10?6 mol/L of Ag(I), the limit of detection (10 blanks), and the enrichment factor were obtained as 1.7%, 2.9 × 10?8 mol/L, and 43.0, respectively. The proposed procedure was then applied successfully for determination of silver ions in different water samples. 相似文献
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ABSTRACTNowadays, mathematical models are widely used to predict climate processes, but little has been done to compare the models. In this study, multiple linear regression (MLR), multi-layer perceptron (MLP) network and adaptive neuro-fuzzy inference system (ANFIS) models were compared for precipitation forecasting. The large-scale climate signals were considered as inputs to the applied models. After selecting the most effective climate indices, the effects of large-scale climate signals on the seasonal standardized precipitation index (SPI) of the Maharlu-Bakhtaran catchment, Iran, simultaneously and with a delay, was analysed using a cross-correlation function. Hence, the SPI time series was forecasted up to four time intervals using MLR, MLP and ANFIS. The results showed that most of the indices were significant with SPI of different lag times. Comparison of the SPI forecast results by MLR, MLP and ANFIS models showed better performance for the MLP network than the other two models (RMSE = 0.86, MAE = 0.74 for the first step ahead of SPI forecasting).
Editor D. Koutsoyiannis; Associate editor F. Pappenberger 相似文献
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T. Nasrabadi G. R. Nabi Bidhendi A. R. Karbassi H. Hoveidi I. Nasrabadi H. Pezeshk F. Rashidinejad 《Environmental Geology》2009,58(4):693-700
Sungun mine is the largest open-cast copper mine in northwest of Iran and is in the primary stages of extraction. The influence
of mining activity on the quality of regional groundwater has been taken in to consideration in this study. Accordingly, sampling
was done from 22 springs in the study area. The concentrations of major anions and cations as well as Al, Cu, Cd, Cr, Fe,
Mn, and Zn were determined for all 22 spring samples in mid-August 2005. The results showed that the concentrations of most
of these elements were below the USA Environmental Protection Agency (EPA) limits; however, Al and Fe concentrations are considered
to be more than limits in a couple of samples. Despite the fact that geological formations are highly weathered and fractured,
the dissolution of minerals within the study area is low. This may be justified by the relatively high alkalinity of local
underground water which keeps metals in solid phase and does not let them enter dissolved phase. Additionally, this may be
attributed to the high velocity of groundwater flows, which do not give enough time for minerals to dissolve. Correlation
coefficients among water chemistry components were determined and the weighted-pair group method was chosen for cluster analysis.
Accordingly, high correlation among Al, Fe and Cr, Cd ,and Cu, sodium absorption ratio (SAR) and Na as well as total hardness
(TH), Ca, and Mg were observed. The chemical characteristics of water compositions on the basis of major ion concentrations
were evaluated on a Schoeller and Piper diagram. Accordingly, the dominant type of water in the region is considered to be
Ca-HCO3 (calcium-bicarbonate type). However, this type of water is also rich in Na, K, and especially Mg. Regarding Schoeller diagram,
the current status of local underground water is good for drinking purposes. By commencing mining excavation with designed
capacity in near future, the minerals will come into contact with air and water resulting in dissolution, especially in ponds,
which, in turn, will increase the concentration of toxic metals in groundwater. Considering future uses of this water including
for drinking, irrigation, industrial purposes, etc., precautions must be taken in to consideration. 相似文献
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