Concentrations of trace elements in marine fish and its risk assessment in Malaysia

Concentrations of trace elements (V, Cr, Mn, Co, Cu, Zn, Ga, Se, Rb, Sr, Mo, Ag, Cd, Sn, Sb, Cs, Ba, Hg, Tl, Pb and Bi) were determined in muscle and liver of 12 species of marine fish collected from coastal areas in Malaysia. Levels of V, Cr, Mn, Co, Cu, Zn, Ga, Sr, Mo, Ag, Cd, Sn, Ba and Pb in liver were higher than those in muscle, whereas Rb and Cs concentrations showed the opposite trend. Positive correlations between concentrations in liver and muscle were observed for all the trace elements except Cu and Sn. Copper, Zn, Se, Ag, Cd, Cs and Hg concentrations in bigeye scads from the east coast of the Peninsular Malaysia were higher than those from the west, whereas V showed the opposite trend. The high concentration of V in the west coast might indicate oil contamination in the Strait of Malacca. To evaluate the health risk to Malaysian population through consumption of fish, intake rates of trace elements were estimated on the basis of the concentrations of trace elements in muscle of fish and daily fish consumption. Some specimens of the marine fish had Hg levels higher than the guideline value by US Environmental Protection Agency (EPA), indicating that consumption of these fish at the present rate may be hazardous to Malaysian people. To our knowledge, this is the first study on multielemental accumulation in marine fish from the Malaysian coast.     

Modelling of the groundwater flow and of tracer movement in the porous and fissured media: Chalk Aquifer (Northern part of Paris Basin,France)

A groundwater flow model has been developed in order to study the chalk aquifer of Paris Basin, based on most of the geological and hydrological available data. The numerical processes are intended to modelling the groundwater flow in the Senonian (Late Cretaceous) formations and to visualize the tracer movement in groundwater resources in the experimental site of LaSalle Beauvais (northern part Paris Basin). Both objectives were achieved as follows: (i) the comprehension of the spatial distribution of the hydraulic conductivity in the chalk aquifer taking into account the characteristics of the hydrogeological system and (ii) the use of the analytical solution for describing one‐dimensional to two‐dimensional solute transport in a unidirectional steady‐state flow tracer with scale‐dependent dispersion. Advection and diffusion mechanisms are taken into account. Comparison between the breakthrough curves of the analytical and the numerical solutions provided an excellent agreement for various ranges of scale‐related transport parameters of interest. The developed power series solution facilitates fast prediction of the breakthrough curves at each observation point. Thus, the derived new solutions are widely applicable and are very useful for the validation of numerical transport. The numerical approach is carried out by MT3DMS, a Modular 3‐D Multi‐Species Transport Model for Simulation of Advection, Dispersion, and Chemical Reactions of Contaminants in Groundwater Systems, and based on total variation‐diminishing method using the ULTIMATE algorithm. The estimation of the infected surface could constitute an approach in water management and allows to prevent the risks of pollution and to manage the groundwater resource from a durable development perspective. Copyright © 2016 John Wiley & Sons, Ltd.     

Investigation of groundwater resources using controlled-source radio magnetotellurics (CSRMT) in glacial deposits in Heby,Sweden

We have combined tensor radio magnetotelluric- (RMT, 15–250 kHz) and controlled source tensor magnetotelluric (CSTMT, 1–12 kHz) data for the mapping of aquifers in gravel formations lying in between crystalline bedrock and clay rich sediments in the Heby area some 40 km west of Uppsala in Sweden. The estimated transfer functions, the impedance tensor and the tipper vector generally satisfy 1D or 2D necessary conditions except for the lowest CSTMT frequencies where near field effects become more dominant.The data measured from 8 profiles were inverted with the Rebocc code of Siripunvaraporn and Egbert (2000) assuming plane wave conditions. This meant that only 12 frequencies in the range of 4–180 kHz could be used. The four lowest frequencies of CSTMT in the range of 1–2.8 kHz were excluded because of source effects. Data from all profiles were inverted with a starting model of 100 Ω-m and a relative error floor of 0.02 on apparent resistivity, corresponding to less than 1^° on phase. Tipper vectors are generally small except when source effects become dominant in the lowest frequencies of CSTMT and were therefore not used for inversion. Comparing with models derived from vertical electrical soundings, refraction and reflection seismic data as well as ground truth from exploration wells assessed the reliability of the deep part of the models. Furthermore we carried out a non-linear resolution analysis to better quantify the depth extent of the aquifers.The inverted models from the Heby area show well the thickness variations of glacial deposits overlying crystalline bedrock. Generally, the upper 20 m of the models have resistivities below 40 Ω-m, taken to represent clay rich formations. Below the clay layer resistivities increase to about 40–400 Ω-m, interpreted to represent sand/gravel formations with a maximum thickness of about 40 m and a width of several hundred metres. This is a potential aquifer that extends in approximately N–S direction for some kilometres.     

New thermal triaxial apparatus for unsaturated soils using the osmotic method

The study of the temperature effects on the behaviour of saturated and unsaturated soils on triaxial paths requires the development of a new triaxial experimental device of 3.5 MPa of confining pressure and equipped with a heating collar-controlled temperature. In addition to this case of the unsaturated soils, a special pedestal is developed, so as to impose suctions up to 9 MPa using an osmotic solution of polyethylene glycol (PEG) 6000 through a permeable semi-membrane. Measurements of the degree of saturation and the variation of volume during tests induce various problems, primarily related to the thermal dilation of the osmotic solution and the cell-water system. These problems have been solved by carrying out a preliminary calibration. The applicability of this new apparatus concerns environmental geotechnics and geological engineering such as the design and behaviour of engineered barriers as well as the behaviour of the receiving layers of storage sites like radioactive waste.     

Use of Natural Pozzolana and Lime for Stabilization of Cohesive Soils

The present study investigates the use of natural pozzolana combined with lime for ground improvement applications. Laboratory tests were undertaken to study the effect of natural pozzolana, lime or a combination of both on the physical and the mechanical characteristics of cohesive soils. Natural pozzolana, lime and natural pozzolana-lime were added to two cohesive soils at ranges of 0–20 and 0–8%, respectively. Consistency, compaction, undrained traxial shear and unconfined compressive strength tests were performed on untreated and treated soil samples to assess the physical and mechanical characteristics of the soil. Treated samples were cured for 1, 7, 28 and 90 days. The results show that the cohesive soils can be successfully stabilized by combining natural pozzolana and lime.     

Review: Satellite-based remote sensing and geographic information systems and their application in the assessment of groundwater potential, with particular reference to India

Various hydrological, geological and geomorphological factors play a major role in the occurrence and movement of groundwater in different terrains. With advances in space technology and the advent of powerful personal computers, techniques for the assessment of groundwater potential have evolved, of which remote sensing (RS) and geographic information systems (GIS) are of great significance. The application of these methods is comprehensively reviewed with respect to the exploration and assessment of groundwater potential in consolidated and unconsolidated formations in semi-arid regions, and specifically in India. The process of such assessment includes the collection of remotely sensed data from suitable sensors and the selection of thematic maps on rainfall, geology, lithology, geomorphology, soil, land use/land cover, drainage patterns, slope and lineaments. The data are handled according to their significance with the assignment of appropriate weights and integrated into a sophisticated GIS environment. The requisite remote sensing and GIS data, in conjunction with necessary field investigations, help to identify the groundwater potential zones effectively.     

GIS-based multi-source database,a strategic tool for sustainable development planning: case of Qalaat Mgouna,Morocco

Sustainable development requires the control and comprehension of natural and anthropic parameters acting on the lifestyle of a target population. It necessitates the envisaging of possible risks related to the change in conditions of the development processes proceeding. Consequently, a database relating to the parameters considered for the planning of durable development programs is necessary. This work, taking the Qalaat Mgouna site as example, shows the utility of the geographic information system (GIS) technology for the gathering and the processing of data concerning natural parameters—geology, morphology, pedology and climate and anthropic parameters—demography, poverty and vulnerability to poverty. The study of the Qalaat Mgouna case shows an urgent need to act for improving the lifestyle of the local population, by adopting sustainable development processes and considering the progressive reduction in the natural resources due to the climatic change and anthropic causes. The result obtained is thus the development of an extensible and multi-source database and thematic maps, available for the planners and serving as a base document for planning development strategies and envisaging the risks associated with execution processes.     

Deficiencies of the vertical slice method in assessment of the seismic earth pressures

Acta Geotechnica - Conventionally, when the method of slice is adopted to assess the earth pressures behind the retaining wall considering a curvilinear failure surface, the mobilized soil mass...