Vertical distribution and mobilization of arsenic in shallow alluvial aquifers of Chapai-Nawabganj district, Northwestern Bangladesh

Core sediments from two boreholes and groundwater from fifty four As-contaminated well waters were collected in the Chapai-Nawabganj area of northwestern Bangladesh for geochemical analysis. Groundwater arsenic concentrations in the uppermost aquifer (10 to 40 m of depth) range from 2.76?C315.15 mg/l (average 48.81 mg/l). Arsenic concentration in sediments ranges from 3.26?C10 mg/kg. Vertical distribution of arsenic in both groundwater and sediments shows that maximum As concentration (462 mg/l in groundwater and 10 mg/kg in sediments) occurs at a depth of 24 m. In January 2008, 2009 and 2010, maximum As concentration occurs at the same depth. Environmental scanning electron microscope (ESEM) with EDAX was used to investigate the presence of major and trace elements in the sediments. The dominant groundwater type is Ca-HCO₃ with high concentrations of As and Fe, but with low levels of NO₃ ^? and SO₃ ^?2. Statistical analysis clearly shows that As is closely associated with Fe (R² = 0.64) and Mn (R² = 0.91) in sediments while As is not correlated with Fe and Mn in groundwater samples. Comparatively low Fe and Mn concentrations in some groundwater, suggest that probably siderite and/or rhodochrosite precipitated as secondary mineral on the surface of the sediment particles. The correlations along with results of sequential leaching experiments suggest that reductive dissolution of FeOOH and MnOOH mediated by anaerobic bacteria represents mechanism for releasing arsenic into the groundwater.     

Preliminary chemical and micromorphological observations on Urartu (800–600 B.C.) ceramics,eastern Turkey

Anatolia has long been a major pottery production center of the ancient world, dating back 7000 cal yr B.P. The Early Iron Age Urartu Kingdom (800–600 B.C.) of eastern Anatolia is known for the production of high‐quality pottery, but little is known regarding firing technology and manufacture of these ceramics. Here we present a preliminary study of Urartu ceramic micromorphology and chemistry and suggest that the Urartus had good knowledge of local geology and intentionally used chemical fluxes (Pb, Rb, and Li) to attain desired firing temperatures. The sophisticated production of Urartu ceramics is comparable to later high‐quality Roman pottery (terra sigillata) procured from the same area. © 2010 Wiley Periodicals, Inc.     

Evaluation and comparison of landslide susceptibility mapping methods: a case study for the Ulus district,Bartın,northern Turkey

The purpose of this study was to investigate the capabilities of different landslide susceptibility methods by comparing their results statistically and spatially to select the best method that portrays the susceptibility zones for the Ulus district of the Bart?n province (northern Turkey). Susceptibility maps based on spatial regression (SR), linear discriminant analysis (LDA), quadratic discriminant analysis (QDA), logistic regression (LR) method, and artificial neural network method (ANN) were generated, and the effect of each geomorphological parameter was determined. The landslide inventory map digitized from previous studies was used as a base map for landslide occurrence. All of the analyses were implemented with respect to landslides classified as rotational, active, and deeper than 5 m. Three different sets of data were used to produce nine explanatory variables (layers). The study area was divided into grids of 90 m × 90 m, and the ‘seed cell’ technique was applied to obtain statistically balanced population distribution over landslide inventory area. The constructed dataset was divided into two datasets as training and test. The initial assessment consisted of multicollinearity of explanatory variables. Empirical information entropy analysis was implemented to quantify the spatial distribution of the outcomes of these methods. Results of the analyses were validated by using success rate curve (SRC) and prediction rate curve (PRC) methods. Additionally, statistical and spatial comparisons of the results were performed to determine the most suitable susceptibility zonation method in this large-scale study area. In accordance with all these comparisons, it is concluded that ANN was the best method to represent landslide susceptibility throughout the study area with an acceptable processing time.     

Enhancement of real‐time hybrid simulation on a shaking table configuration with implementation of an advanced control method

This paper presents the implementation of Three Variable Control (TVC), an advanced control method, to the existing hybrid simulation (HS) system at the University of California, Berkeley. Motivation, background, and implementation of the TVC are explained together with modifications in the existing HS system. An application, which consists of the real‐time HS of electrical disconnect switches on a shaking table configuration, demonstrates successful implementation of the TVC. The presented application also covers other HS‐related features, namely employment of a three‐dimensional analytical substructure, real‐time HS‐compatible operator‐splitting integration method, and an efficient equation solver for faster computations. Copyright © 2014 John Wiley & Sons, Ltd.     

Seismic performance evaluation of high voltage disconnect switches using real‐time hybrid simulation: I. System development and validation

This paper presents the development and validation of a real‐time hybrid simulation (RTHS) system for efficient dynamic testing of high voltage electrical vertical‐break disconnect switches. The RTHS system consists of the computational model of the support structure, the physical model of the insulator post, a small shaking table, a state‐of‐the‐art controller, a data acquisition system and a digital signal processor. Explicit Newmark method is adopted for the numerical integration of the governing equations of motion of the hybrid structure, which consists of an insulator post (experimental substructure) and a spring‐mass‐dashpot system representing the support structure (analytical substructure). Two of the unique features of the developed RTHS system are the application of an efficient feed‐forward error compensation scheme and the ability to use integration time steps as small as 1 ms. After the development stage, proper implementation of the algorithm and robustness of the measurements used in the calculations are verified. The developed RTHS system is further validated by comparing the RTHS test results with those from a conventional shaking table test. A companion paper presents and discusses a parametric study for a variety of geometrical and material configurations of these switches using the developed RTHS system. Copyright © 2013 John Wiley & Sons, Ltd.     

Isotopic composition of some egyptian galena by thermal emission mass spectrometry

Summary The present paper contains some lead isotope analyses on galena specimens occuring in the central part of the Eastern Desert of Egypt. Thermal emission mass spectrometric technique is applied to these analyses. Recent methods of calculations for galena dating are used in determining the geochronological significance of the data. The lead isotopic composition of the samples has revealed the possible existence of two orogenic events accompanied with metallization that took place about 1000 m.y. and 600 m.y. ago.     

Mass spectrometric study of some selected galenas from the Eastern Desert of Egypt

Summary Thermal emission mass spectrometric technique is applied to the determination of the lead isotopic composition of some selected galenas from the Eastern Desert of Egypt. Recent methods of calculations for galena dating are used in determining the geochronological significance of the data. A correlation is made between the data obtained and the modes of occurrences of the deposits to enter any processes that cause their isotopic variations.     

Environmental impacts of El Arish power plant on the Mediterranean coast of Sinai, Egypt

A monitoring program was undertaken to evaluate the adverse impacts of the El Arish power plant on the northeastern Sinai coast of Egypt. This program spanned 28 months and includes intensive hydrographic surveying, measurements of waves, longshore current, littoral drift, currents behind the breaker zone, offshore currents, sea-level variation and water quality. The shoreline dynamics of the region have been substantially disrupted due to the high-intensity longshore transport and the interruption of longshore transport by the shore-perpendicular intake breakwaters. Maximum erosion of 5.5 m/year has been documented east of the breakwater. This erosion has been continuing eastwards, threatening the resort centers on the downcoast beaches. On the other hand, accretion (11.7 m/year) is recorded along the western side of the breakwater, accumulating great volumes of sand which is transported to the east by littoral currents. Part of this sand enters the intake basin, causing sedimentation problems by the easterly and westerly littoral drifts and cross-shore currents. In other respect, an unprotected offshore channel dredged in front of the water discharger, east of the intake, acts as an effective trap for the predominantly easterly sand drift, subsequently interrupting sediments moving from the east, accelerating processes of erosion to the east. The cooling and wastewater discharging from the discharger to the sea are insignificantly warmer than the upcoast water and not contaminated with chemical wastes. The thermal and chemical plume has no significant effect on the quality of the coastal water in the region.