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41.
AbstractThe multi-layered Jeffara de Gabes aquifer system is greatly influenced by tectonics. This system is limited at the base and laterally by evaporite layers and has lateral contacts with the sebkhas (salt flats). The groundwater in this aquifer is characterized by high salinity (3–10 g L-1). Multivariate statistical analysis and a geochemical approach were applied to determine the influence of the evaporite layers and sebkhas on the hydrochemical quality of the Jeffara de Gabes aquifer, and to understand the processes governing its salinity. According to these methods, and based in part on the Sr2+/Ca2+ ratio, it is demonstrated that the strong salinity of the groundwater is due to interactions between water and the evaporite layers that act as a substratum of this aquifer, as well as saltwater intrusion from the sebkhas. Moreover, the medium- to poor-quality groundwaters are characterized by geochemical interactions: cationic exchange and the precipitation/dissolution process of minerals in the aquifer formations.Editeur Z.W. KundzewiczCitation Ben Alaya, M., Zemni, T., Mamou, A. et Zargouni, F., 2014. Acquisition de salinité et qualité des eaux d’une nappe profonde, Tunisie: approche statistique et géochimique. Hydrological Sciences Journal, 59 (2), 395–419. 相似文献
42.
Lepidocrocite (γ‐FeOOH) nanoparticles were synthesized from iron(II) sulfate solution and characterized using X‐ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform‐IR (FT‐IR), nitrogen adsorption, and point of zero charge pH (pHPZC) analyses. TEM, XRD, and FT‐IR analyses proved the synthesis of nano‐lepidocrocite. Surface area and pHPZC of the synthesized lepidocrocite were 68.1 m2 g?1 and 4.8, respectively. Utilization of the synthesized lepidocrocite in the adsorption of Lanacron brown S‐GL (LBS‐GL) from aqueous solutions was investigated, and the effect of lepidocrocite dosage, pH, temperature, and contact time on this process were optimized and modeled using response surface methodology approach. The lepidocrocite dosage of 0.015 g, pH 3.5, temperature of 38°C, and contact time of 100 min were determined as optimum adsorption conditions. Isotherm and kinetics of the adsorption process were analyzed at the optimum conditions. The equilibrium data were fitted well to the Langmuir isotherm model. The maximum monolayer adsorption capacity was 528.21 mg g?1. The adsorption process was described by the pseudo‐second‐order kinetic model. Furthermore, the effect of pH on the desorption of LBS‐GL was investigated. High LBS‐GL desorption efficiency was achieved at a high pH value. 相似文献
43.
Evaluation of Methods for Determining Crack Initiation in Compression Tests on Low-Porosity Rocks 总被引:7,自引:6,他引:1
Laboratory testing of rocks is traditionally carried out to determine the peak strength using the ISRM Suggested Methods or other suitable standards. However, it is well known that in low-porosity crystalline rocks there are at least three distinct stages of compressive loading that can be readily identified if the stress–strain response is monitored during the loading process: (1) crack initiation, (2) unstable crack growth, i.e., crack coalescence and (3) peak strength. Crack initiation is noted as the first stage of stress-induced damage in low-porosity rocks, yet the suggested guidelines of the ISRM for compression tests make no mention of crack initiation. In addition, recent research suggests that crack initiation can be used as an estimate for the in situ spalling strength, commonly observed around underground excavations in massive to moderately jointed brittle rocks. Various methods have been proposed for identifying crack initiation in laboratory tests. These methods are evaluated using ten samples of ?sp? Diorite and the results are compared with a simplified method, lateral strain response. Statistically, all methods give acceptable crack-initiation values. It is proposed that the ISRM Suggested Methods be revised to include procedures suitable for establishing the crack-initiation stress. 相似文献
44.
Hydrogeochemistry of Groundwater and Its Suitability for Drinking and Agricultural Use in Nahavand,Western Iran 总被引:1,自引:0,他引:1
Mohsen Jalali 《Natural Resources Research》2011,20(1):65-73
Groundwater is the major source of drinking water in Nahavand city. However, the groundwater quality at the agricultural areas
has been deteriorating in recent years. Ground water quality monitoring is a tool which provides important information for
water management and sustainable development of the water resources in Nahavand. Hydrochemical investigations were carried
out in an agricultural area in Nahavand, western Iran, to assess chemical composition of groundwater. In this study, 64 representative
groundwater samples were collected from different irrigation wells and analyzed for pH, electrical conductivity, major ions,
and nitrate. The results of the chemical analysis of the groundwater showed that concentrations of ions vary widely and the
most prevalent water type is Ca–Mg–HCO3, followed by other water types: Ca–HCO3, Ca–Na–HCO3, and Na–Cl, which is in relation with their interactions with the geological formations of the basin, dissolution of feldspars
and chloride and bicarbonate minerals, and anthropogenic activities. Thirty-seven percent of the water samples showed nitrate
(NO3
−) concentrations above the human affected value (13 mg L−1). The phosphorous (P) concentration in groundwater was between 0.11 and 0.90 mg L−1, with an average value of 0.30 mg L−1, with all of the samples over 0.05 mg L−1. The most dominant class C2-S1 (76.5%) was found in the studied area, indicating that sodicity is very low and salinity is
medium, and that these waters are suitable for irrigation in almost all soils. Agronomic practices, such as cultivation, cropping,
and irrigation water management may decrease the average NO3
− concentration in water draining from the soil zone. 相似文献
45.
Nitrate pollution of groundwater in Toyserkan,western Iran 总被引:5,自引:2,他引:3
Mohsen Jalali 《Environmental Earth Sciences》2011,62(5):907-913
A total of 95 groundwater samples were collected from Toyserkan, western Iran to assess the chemical composition and nitrate
(NO3
−) status of groundwater. The most prevalent water type is Ca–HCO3 followed by water types Ca–Mg–HCO3. In comparison with the World Health Organization (WHO) drinking water guideline of 50 mg l−1 for NO3
−, a total of nine wells (9.5%) showed higher concentrations. In 36% of samples (34) NO3
− concentration was low (<20 mg l−1), and in 53.7% of samples (51), in the range of 20–50 mg l−1. The samples were classified into four groups based on NO3
− and chloride (Cl−) concentrations. Of the samples, 40% were classified as group 4 and were relatively high in Cl− and NO3
− (Cl− > 47 mg l−1, NO3
− > 27 mg l−1). The high correlation between NO3
− and Cl− (r = 0.86, p < 0.01) is consistent with a manure source, resulting from the practice of adding salt to animal feed. Pollution of groundwaters
appeared to be affected by the application of inorganic fertilizer at greater than agronomic rates, Cl-salt inputs, and irrigation
practice. 相似文献
46.
Sharifi Mortaza Tabatabaei Manesh Seyed Mohsen Safaei Homayon Karimi Somaye 《Geotectonics》2013,47(6):495-508
The metamorphic complex of the North Golpayegan is part of the Sanandaj-Sirjan Zone. There are at least three distinct stages of deformation in this complex. Throughout the first stage, Paleozoic and Mesozoic sedimentary rocks have experienced regional metamorphism during Late Jurassic tectonic events related to the subduction of the Neo-Tethys oceanic lithosphere under the Iranian microcontinent. During the second deformation stage in the Late Cretaceous-Paleocene, the rocks have been mylonitized. The third stage of deformation in the region has led to folding and faulting superimposed on previous structures, and to exhumation of the metamorphic complex. This stage has determined the current morphology and N70E strike of the complex. The mylonitic zones of the second stage of deformation have been formed along the dextral transpressional faults. During the third stage of deformation and exhumation of the metamorphic complex, the mylonitic zones have been uplifted to the surface. The granitoids in the metamorphic complex have been injected along the extensional shear fractures related to the dextral transpressional displacements. The granitoids have been transformed into mylonites within the synthetic or antithetic shear zones. These granitoids are recognized as syncollision type (CCG) and have been formed at the end of orogenic events synchronous to the collision between the Arabian and the Iranian plates at the Late Cretaceous-Paleocene. 相似文献
47.
Mohsen Abbasnia Taghi Tavousi Mahmood Khosravi 《Asia-Pacific Journal of Atmospheric Sciences》2016,52(4):371-377
Identification and assessment of climate change in the next decades with the aim of appropriate environmental planning in order to adapt and mitigate its effects are quite necessary. In this study, maximum temperature changes of Iran were comparatively examined in two future periods (2041-2070 and 2071-2099) and based on the two general circulation model outputs (CGCM3 and HADCM3) and under existing emission scenarios (A2, A1B, B1 and B2). For this purpose, after examining the ability of statistical downscaling method of SDSM in simulation of the observational period (1981-2010), the daily maximum temperature of future decades was downscaled by considering the uncertainty in seven synoptic stations as representatives of climate in Iran. In uncertainty analysis related to model-scenarios, it was found that CGCM3 model under scenario B1 had the best performance about the simulation of future maximum temperature among all of the examined scenario-models. The findings also showed that the maximum temperature at study stations will be increased between 1°C and 2°C in the middle and the end of 21st century. Also this maximum temperature changes is more severe in the HADCM3 model than the CGCM3 model. 相似文献
48.
49.
50.
Spatio-temporal analysis of crime by developing a method to detect critical distances for the Knox test 总被引:1,自引:0,他引:1
Mohsen Kalantari Bamshad Yaghmaei Somaye Ghezelbash 《International journal of geographical information science》2016,30(11):2302-2320
The present study examined and compared spatio–temporal interaction of the theft of car parts, shop burglary and motorcycle theft in the central business district (CBD) of the city of Zanjan in Iran. The Knox test was selected to detect spatio–temporal interaction. This test has been criticized as being subjective because the selection of critical distances is arbitrary; thus, a method is proposed to detect critical distances in the Knox test using the mean distance, natural breaks classification of nearest neighbour (NN) distance and Ripley’s k function. Results show obvious differences between the spatio-temporal clusters of the three sets of crimes. They also indicate that changing the spatial cut-offs within a cluster creates different temporal patterns. Of the three criteria for determining critical distances, NN classification based on natural breaks showed more interactions than the other methods. 相似文献