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41.
Mohammad Mokammel Haque Hussien Abdulrahman Al Attas Mutaz Ali Hassan 《Arabian Journal of Geosciences》2016,9(6):464
The concentrations of 16 trace elements (Ag, Al, As, B, Ba, Cd, Cr, Cu, Hg, Mn, Ni, Pb, Se, Ti, U, and Zn) in drinking water from Najran City, Saudi Arabia, were determined by inductively coupled plasma-mass spectrometry (ICP-MS) and compared with local, regional, and international guidelines. Water samples from 22 water treatment plants and 13 commercial bottled water brands were analyzed. Except for B and U, the trace element concentrations were below the permitted limits defined in SASO, GSO, and WHO drinking water quality guidelines. The B concentrations in three brands of bottled water were 533.19, 602.29, and 1471.96 μg/L, which were all higher than the GSO and SASO limit (500 μg/L). The U concentrations were higher than the SASO limits for drinking water in two samples; one in treatment plant (2.39 μg/L) and another in foreign bottled water (2.17 μg/L). The median As, Ba, Cu, Ni, U, and Zn concentrations were statistically significantly higher in the treatment plant water samples than those in the bottled water samples, and conversely, the B concentrations were higher in the bottled water samples. The Cd, Hg, and Ti concentrations were below the detection limits of ICP-MS in all of the water samples. Apart from few exceptions, trace element concentrations in drinking water of Najran City were all within limits permitted in the national, regional, and international drinking water quality guideline values. 相似文献
42.
Relationship between different geomechanical and acoustic properties measured from seven laboratory-tested unconsolidated natural sands with different mineralogical compositions and textures were presented. The samples were compacted in the uniaxial strain configuration from 0.5 to 30 MPa effective stress. Each sand sample was subjected to three loading–unloading cycles to study the influence of stress reduction. Geomechanical, elastic and acoustic parameters are different between normal compaction and overconsolidation (unloaded and reloaded). Stress path (K0) data differ between normal consolidated and overconsolidated sediments. The K0 value of approximately 0.5 is founded for most of the normal consolidated sands, but varies during unloading depending on mineral compositions and textural differences. The K0 and overconsolidation ratio relation can be further simplified and can be influenced by the material compositions. K0 can be used to estimate horizontal stress for drilling applications. The relationship between acoustic velocity and geomechanical is also found to be different between loading and unloading conditions. The static moduli of the overconsolidated sands are much higher than normal consolidated sands as the deformation is small (small strain). The correlation between dynamic and static elastic moduli is stronger for an overconsolidation stage than for a normal consolidation stage. The results of this study can contribute to geomechanical and acoustic dataset which can be applied for many seismic-geomechanics applications in shallow sands where mechanical compaction is the dominant mechanism. 相似文献
43.
Zhao Yu Zhang Yongfa Yang Haiqing Tian Xin Emdadul Haque Md. Mouhamadou Faouziatou 《Natural Resources Research》2020,29(6):3743-3769
Natural Resources Research - Due to unbalanced spatial distribution and insufficient capacity allocation of water resources in the Jinqu Basin, developing and utilizing the red bed groundwater... 相似文献
44.
Arsenic (As) and antimony (Sb) concentrations and speciation were determined along flow paths in three groundwater flow systems,
the Carrizo Sand aquifer in southeastern Texas, the Upper Floridan aquifer in south-central Florida, and the Aquia aquifer
of coastal Maryland, and subsequently compared and contrasted. Previously reported hydrogeochemical parameters for all three
aquifer were used to demonstrate how changes in oxidation–reduction conditions and solution chemistry along the flow paths
in each of the aquifers affected the concentrations of As and Sb. Total Sb concentrations (SbT) of groundwaters from the Carrizo Sand aquifer range from 16 to 198 pmol kg−1; in the Upper Floridan aquifer, SbT concentrations range from 8.1 to 1,462 pmol kg−1; and for the Aquia aquifer, SbT concentrations range between 23 and 512 pmol kg−1. In each aquifer, As and Sb (except for the Carrizo Sand aquifer) concentrations are highest in the regions where Fe(III)
reduction predominates and lower where SO4 reduction buffers redox conditions. Groundwater data and sequential analysis of the aquifer sediments indicate that reductive
dissolution of Fe(III) oxides/oxyhydroxides and subsequent release of sorbed As and Sb are the principal mechanism by which
these metalloids are mobilized. Increases in pH along the flow path in the Carrizo Sand and Aquia aquifer also likely promote
desorption of As and Sb from mineral surfaces, whereas pyrite oxidation mobilizes As and Sb within oxic groundwaters from
the recharge zone of the Upper Floridan aquifer. Both metalloids are subsequently removed from solution by readsorption and/or
coprecipitation onto Fe(III) oxides/oxyhydroxides and mixed Fe(II)/Fe(III) oxides, clay minerals, and pyrite. Speciation modeling
using measured and computed Eh values predicts that Sb(III) predominate in Carrizo Sand and Upper Floridan aquifer groundwaters,
occurring as the Sb(OH)30 species in solution. In oxic groundwaters from the recharge zones of these aquifers, the speciation model suggests that Sb(V)
occurs as the negatively charged Sb(OH)6− species, whereas in sufidic groundwaters from both aquifers, the thioantimonite species, HSb2S4
− and Sb2S4
2−, are predicted to be important dissolved forms of Sb. The measured As and Sb speciation in the Aquia aquifer indicates that
As(III) and Sb(III) predominate. Comparison of the speciation model results based on measured Eh values, and those computed
with the Fe(II)/Fe(III), S(-II)/SO4, As(III)/As(V), and Sb(III)/Sb(V) couples, to the analytically determined As and Sb speciation suggests that the Fe(II)/Fe(III),
S(-II)/SO4 couples exert more control on the in situ redox condition of these groundwaters than either metalloid redox couple. 相似文献
45.
Wai Loong Chong Asadul Haque Ranjith Pathegama Gamage Akm Shahinuzzaman 《Arabian Journal of Geosciences》2013,6(5):1639-1646
Rock mass is a highly complex entity where the strength and deformation behaviour can be significantly affected by its secondary structures such as joints, fissures and bedding planes. Whilst many research works have been conducted to study the behaviour of a specific rock mass, a thorough understanding of its strength and deformation behaviour incorporating different joint sets has not been established. In this study, a comprehensive numerical modelling using a three-dimensional distinct element code, 3DEC, was undertaken to study the strength and deformation behaviour of a mudstone, locally found in Melbourne, in unconfined and confined states. The initial unconfined model established for intact mudstone was calibrated against the well-established laboratory-based empirical strength relationships and subsequently compared with some strength test data available for field samples. The intact unconfined model was then extended to study the strength behaviour in the confined state. The results obtained from this confined intact model were compared with existing strength criteria and were found in good agreement. The confined model was extended further to investigate the effects of joint sets and dip angles on the rock mass strength and deformation behaviour by incorporating two different joint configurations (one-joint and two-joint) with varying dip angles (0°–90°). This study found that the rock mass strength in a confined state varied significantly between the two joint configurations. 相似文献
46.
A Novel Testing Apparatus for Hydromechanical Investigation of Rocks: Geo-Sequestration of Carbon dioxide 总被引:1,自引:0,他引:1
R. Shukla P. G. Ranjith S. K. Choi A. Haque 《Rock Mechanics and Rock Engineering》2012,45(6):1073-1085
This paper presents the design, development and application of a new multi-phase high-pressure and elevated temperature rock hydromechanical testing apparatus for the investigation of reservoir and cap rock behaviour in carbon geo-sequestration projects. The triaxial apparatus is designed to support high confining stress, injection pressures and higher temperatures to imitate the natural thermo-hydro-geomechanical conditions of deep underground geological formations. The apparatus also includes an acoustic emission device for the study of the mechanical failure behaviour of rocks under compression. The apparatus is designed to support a range of different rock specimen sizes from 34 to 54?mm in diameter. Since sequestration projects involve the injection of supercritical carbon dioxide, which is extremely sensitive to temperature and pressure, and is highly corrosive in nature, special precautions were taken in the design and manufacture of the apparatus. The data acquisition system is powered and calibrated in accordance with each of the sensors and is guided by a series of in-house developed and commercial softwares for data storage and analysis. The methodology for conducting advanced testing on cap rock and reservoir rocks with the injection of water and supercritical CO2 is presented with the appropriate theory. Some preliminary tests have been carried out on sandstone specimens sourced from the Melbourne region using the newly designed apparatus and the results are presented in this paper. 相似文献
47.
A bioreactor landfill is operated to enhance refuse decomposition, gas production, and waste stabilization. Some of the potential
advantages of bioreactor include rapid stabilization of waste, increased landfill gas generation, gain in landfill space,
enhanced leachate treatment, and reduced post closure maintenance period. Due to the accelerated decomposition and settlement
of solid waste, bioreactor landfills are gaining popularity as an alternative to the conventional Subtitle D landfills. However,
the addition of leachate to accelerate the decomposition changes the physical and engineering characteristic of waste and
therefore affects the geotechnical characteristics of waste mass. The changes in the physical and mechanical characteristics
of solid waste with time and decomposition are expected to affect the shear strength of waste mass. The objective of this
paper is to analyze the stability of solid waste slopes within the bioreactor landfills, as a function of time and decomposition.
The finite element program PLAXIS is used for numerical modeling of bioreactor landfills. Stability analysis of bioreactor
landfills was also performed using limit equilibrium program STABL. Finally the results from finite element program PLAXIS
and limit equilibrium program STABL are compared. GSTABL predicted a factor of safety of more than 1 in all the cases analyzed,
whereas PLAXIS predicted a factor of safety of less than 1 at advanced stages for a slope of 2:1. However, the interface failures
between solid waste and landfill liners have not been considered in this paper. 相似文献
48.
This paper presents the results from a pile load testing program for a bridge construction project in Louisiana. The testing includes two 54-in. open-ended spun cast concrete cylinder piles, one 30-in. open-ended steel pile and two (30- and 16-in.) square prestressed concrete (PSC) piles driven at two locations with very similar soil conditions. Both cone penetration tests (CPTs) and soil borings/laboratory testing were used to characterize the subsurface soil conditions. All the test piles were instrumented with vibrating wire strain gauges to measure the load distribution along the length of the test piles and measure the skin friction and end-bearing capacity, separately. Dynamic load tests were performed on all test piles at different times after pile installations to quantify the amount of setup with time. Static load tests were also performed on the PSC and open-ended steel piles. Due to expected large pile capacities, the statnamic test method was used on the two open-ended cylinder piles. The pile capacities of these piles were evaluated using various CPT methods (such as Schmertmann, De Ruiter and Beringen, LCPC, Lehane et al. methods). The result showed that all the methods can estimate the skin friction with good accuracy, but not the end-bearing capacity. The normalized cumulative blow counts during pile installation showed that the blow count was always higher for the PSC piles compared to the large-diameter open-ended cylinder pile, regardless of pile size and hammer size. Setup was observed for all the piles, which was mainly attributed to increase in skin frictions. The setup parameters “A” were back-calculated for all the test piles and the values were between 0.31 and 0.41. 相似文献
49.
C. Emdad Haque Dale Dominey-Howes Nuray Karanci Gerassimos Papadopoulos Ahmet Yalciner 《Natural Hazards》2003,29(3):307-308
Editorial Introduction
Editorial 相似文献50.
Arsenic (As) concentrations and speciation were determined in groundwaters along a flow-path in the Upper Floridan aquifer (UFA) to investigate the biogeochemical “evolution“ of As in this relatively pristine aquifer. Dissolved inorganic As species were separated in the field using anion-exchange chromatography and subsequently analyzed by inductively coupled plasma mass spectrometry. Total As concentrations are higher in the recharge area groundwaters compared to down-gradient portions of UFA. Redox conditions vary from relatively oxic to anoxic along the flow-path. Mobilization of As species in UFA groundwaters is influenced by ferric iron reduction and subsequent dissolution, sulfate reduction, and probable pyrite precipitation that are inferred from the data to occur along distinct regions of the flow-path. In general, the distribution of As species are consistent with equilibrium thermodynamics, such that arsenate dominates in more oxidizing waters near the recharge area, and arsenite predominates in the progressively reducing groundwaters beyond the recharge area. 相似文献