Evaluation of the effectiveness of carbonaceous adsorbents on simultaneous extraction of heavy metals: a comparative study     

M. Behzadi  M. A. Taher  F. Hassani Moghaddam 《International Journal of Environmental Science and Technology》2017,14(5):999-1010

A solid-phase extraction procedure was described for the quantitative extraction of a mixture of lead, cadmium, copper and bismuth ions on modified multiwalled carbon nanotubes, graphene oxide nanosheets, activated carbon and carbon black, individually. Then, the adsorbed analytes were eluted with HCl and introduced directly to electrothermal atomic absorption spectrometry. The surface morphology of the adsorbents was investigated by field-emission scanning electron microscopy. The parameters affecting the adsorption–elution process such as pH and flow rate of the sample solution—type, concentration, volume and flow rate of eluent were optimized in detail. Adsorption capacities, breakthrough volumes and enrichment factors were also studied. Wide calibration curves with good correlation coefficients, low detection limits and acceptable relative standard deviations were obtained for all analytes on different adsorbents. The results showed, when nanoadsorbents were used, higher adsorption and recoveries were obtained for all of the studied metal ions. The proposed method has been applied to the determination of Pb(II), Cd(II), Cu(II) and Bi(III) in water, wastewaters, human urine and human hair samples. The spiked recoveries were in the range 93.0–106%. Also, the accuracy of the method was validated by analyzing a certified reference material.  相似文献   

Enhanced CE-QUAL-W2 model to predict the fate and transport of volatile organic compounds in water body: Gheshlagh reservoir as case study     

Abbas Afshar  Farzaneh Feizi  Ameneh Yousefi Moghadam  Motahareh Saadatpour 《Environmental Earth Sciences》2017,76(23):803

Intentional and/or accidental volatile organic compound (VOC) spill into water bodies may lead to severe contamination and health problems in water infrastructures. The importance and widespread use of petroleum products and the threats posed by these products on surface water resources in Iran necessitates the access to numerical hydrodynamic and water quality simulation models with appropriate capabilities. Simulation the fate and transport of VOC in both flowing and standing water bodies is a fairly complex problem. In this research, CE-QUAL-W2 model is modified to simulate the fate and transport of VOC [i.e., Methyl tert-butyl ether (MTBE), benzene] in standing and flowing water bodies. The performance of the modified CE-QUAL-W2 model is evaluated in a MTBE pollution spill at Khalife-Tarkhan river along the headwaters of Gheshlagh reservoir, Kordestan, Iran. The results show the modified CE-QUAL-W2 model’s capability to depict the spatial and temporal variation of MTBE in comparison with recorded data from MTBE spill event of Gheshlagh reservoir. Based on the simulation results of modified CE-QUAL-W2 model, reservoir cleanup time in different meteorological and hydrological scenarios is evaluated. The results show Gheshlagh reservoir cleanup time reduced in scenarios that included air temperature reduction, wind speed increasing, and high inflow condition.  相似文献   

Geochemical and qualitative assessment of groundwater of the High Mekerra watershed,NW Algeria     

Bachir Hallouche  Abbas Marok  Lahcen Benaabidate  Yagoubia Berrahal  Fatiha Hadji 《Environmental Earth Sciences》2017,76(9):340

Groundwater constitutes the main source of water supply in the High Mekerra watershed of northwestern Algeria. This resource is currently under heavy pressures to meet the growing needs of drinking water and irrigation. This study assesses the geochemical characteristics of groundwater of the High Mekerra watershed at 21 points distributed across the two main aquifers (Ras El Ma and Mouley Slissen) in the region. Hydrochemical facies of Ras El Ma groundwater are dominantly MgCl and CaCl type, while those of Mouley Slissen groundwater are of CaHCO₃ type. Principal component analysis shows a strong correlation between groundwater mineralization and Ca²⁺, Na⁺, Cl^? and SO₄ ^2? ions stemming from the dissolution of carbonates, gypsum and anhydrite. Groundwater mineralization evolves from south to north. Geochemical modeling shows that the High Mekerra groundwater is saturated with respect to calcite and dolomite and undersaturated with respect to gypsum and anhydrite. Nitrate concentrations that exceed the WHO standard (50 mg L^?1) at several points are linked to the agro-pastoral activities in this region.  相似文献   

Earth Fissuring and Land Subsidence in Western Saudi Arabia   总被引：4，自引：0，他引：4  

Bankher  Khalid A.  Al-Harthi  Abbas A. 《Natural Hazards》1999,20(1):21-42

The present investigation deals with the engineering geological evaluation of earth fissuring associated with land subsidence in Wadi Al-Yutamah. The investigations include surface mapping and sampling, in situ and laboratory soil testing, water well inventory, geophysical survey, and monitoring of open fissures and the level of the wadi floor.The earth fissures in the area developed as a result of land subsidence due to man-induced water level declines caused by pumping water from the wadi aquifer above a safe yield. This situation has produced a compaction of underlying unconsolidated sediments and formed hair fissures above ridges and steps of buried surface bedrock. These hair fissures enlarged later after flood erosion and possible enhancement with hydrocompaction.The wadi soil in the study area consists mainly of silt of low plasticity, low density and high void ratio and it was classified as loess like material and collapsing soil. The settlement in the area is greatly increased by excessive wetting under constant pressures. The calculated coefficients of subsidence (collapse) show that the wadi soils were considered to pose moderate problems when wetted.Monitoring of the existing open earth fissures using extensometers indicates that the width of the fissure increases after flooding or rain falls. Monitoring of the ground level using GPS techniques, shows a good relation between the declination of the water table and the subsidence of the ground of the wadi floor.  相似文献   

An efficient numerical model for incompressible two-phase flow in fractured media   总被引：1，自引：0，他引：1  

Hussein Hoteit  Abbas Firoozabadi 《Advances in water resources》2008

Various numerical methods have been used in the literature to simulate single and multiphase flow in fractured media. A promising approach is the use of the discrete-fracture model where the fracture entities in the permeable media are described explicitly in the computational grid. In this work, we present a critical review of the main conventional methods for multiphase flow in fractured media including the finite difference (FD), finite volume (FV), and finite element (FE) methods, that are coupled with the discrete-fracture model. All the conventional methods have inherent limitations in accuracy and applications. The FD method, for example, is restricted to horizontal and vertical fractures. The accuracy of the vertex-centered FV method depends on the size of the matrix gridcells next to the fractures; for an acceptable accuracy the matrix gridcells next to the fractures should be small. The FE method cannot describe properly the saturation discontinuity at the matrix–fracture interface. In this work, we introduce a new approach that is free from the limitations of the conventional methods. Our proposed approach is applicable in 2D and 3D unstructured griddings with low mesh orientation effect; it captures the saturation discontinuity from the contrast in capillary pressure between the rock matrix and fractures. The matrix–fracture and fracture–fracture fluxes are calculated based on powerful features of the mixed finite element (MFE) method which provides, in addition to the gridcell pressures, the pressures at the gridcell interfaces and can readily model the pressure discontinuities at impermeable faults in a simple way. To reduce the numerical dispersion, we use the discontinuous Galerkin (DG) method to approximate the saturation equation. We take advantage of a hybrid time scheme to alleviate the restrictions on the size of the time step in the fracture network. Several numerical examples in 2D and 3D demonstrate the robustness of the proposed model. Results show the significance of capillary pressure and orders of magnitude increase in computational speed compared to previous works.  相似文献   

Vulnerability evaluation of a coastal aquifer via GALDIT model and comparison with DRASTIC index using quality parameters   总被引：1，自引：1，他引：0  

Hamid Kardan Moghaddam  Fatemeh Jafari 《水文科学杂志》2017,62(1):137-146

In recent years, environmental assessments of groundwater resources have resulted in the development of models that help identify the vulnerable zones. An aquifer is investigated using both GALDIT and DRASTIC indices. The GALDIT model is developed to determine the vulnerability of coastal aquifers in terms of saltwater intrusion whereas the DRASTIC model is generally applicable to all aquifers. Having compared the results of both the GALDIT and DRASTIC models with quality parameters, the salinity model proved to be more appropriate in identifying the vulnerability of coastal aquifers. The results show a Pearson correlation coefficient between TDS and the GALDIT vulnerability map of 0.58 while the corresponding value for the DRASTIC index is 0.48.