Four sequential chemical extraction schemes for metal analysis (a 4-step modified protocol originally proposed by the Standards, Measurements and Testing Programme (SM&T - formerly BCR) of the European Union, Tessier and Hall 5-step procedures and 6-step Grimalt's scheme) were compared. Each procedure was applied to four sediment samples collected from two rivers, Nakagawa (NR) and Tamagawa (TR), Tokyo, Japan. Additionally, a certified marine sediment reference material (JMS-1) was also extracted for the comparison. To evaluate the partitioning of metals among different geochemical forms, the concentration of chromium (Cr), copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn) were measured by Zeeman-corrected atomic absorption spectrometry. Other major elements and mineralogy of sediments were also determined on bulk prior to extracting by X-ray fluorescence (XRF) and X-ray diffraction (XRD) analysis, respectively, which allowed qualitative correlation between the fractionation results obtained and the presence of defined geochemical phases. The total concentrations of metals were determined after strong acid attack and the analytical precision was verified by using JMS-1. Significant proportions of elements were found in non-residual fractions among the schemes (average 83, 91, 76, 93 and 59% for Cr, Cu, Pb, Zn and Ni, respectively) in the more anthropogenically impacted NR sediments. The highest mobility was observed for Pb and Zn among the four schemes while the lowest was for Cr and Ni. Results of the comparison among the total metal levels for the four schemes based upon the sum of sequential extraction steps for each element showed significant differences for Cr, Ni and Zn. On the other hand, the sum of non-residual phases of the four schemes showed no significant differences for Cr, Cu and Zn but the SM&T and Hall schemes showed significant differences from others for Pb and Ni, respectively. Generally, good recoveries were achieved with the Hall scheme (range 92-109%) and the Fe-Mn oxides occlued phase of this scheme was the most effective owing to the high tendency to extract metals. In addition, Grimalt scheme produced the lowest recovery of Cr and the concentrations of residual fraction of other elements were also lower.

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  Carbon fibers are excellent mixing materials for mortar or concrete because they can prevent the generation of fracture inside the material. Carbon fibers have low specific gravity, high strength, and high elastic modulus; further, they are inert to many chemical substances and also have excellent heat resistance. For these reasons, carbon fibers can be used as excellent mixing materials for mortar or concrete.
This study was initially started for the purpose of preventing the collapse of houses during the Great Hanshin-Awaji Earthquake; however, at present, it is also aimed at countering the effects of the Niigata Earthquake.
Carbon fiber reinforced plastics (CFRP) are currently being used as structural materials in aircrafts, automobiles, etc., and will be discarded in large quantities as scrap. Hence, the objective of this study also includes the development of a breakthrough approach for recycling scrap CFRPs for application as mixing materials in concrete or mortar. Through this study, two new materials have been developed. The first material is carbon fiber reinforced mortar-A (CFRM-A) in which polyacrylonitrile (PAN) fiber is mixed into mortar; the second material is CFRM-B in which chopped CFRPs are mixed with CFRM-A. The fractural strength and elastic modulus of these materials have been measured. The results show that CFRM-B has sufficient capacity to be applied to the construction of earthquake-resistant structures. In addition, the fundamental experiments on the heat treatment of CFRPs are performed and the carbon fibers are extracted.
A mass loss occurs in CFRPs at approximately 700 K; this becomes constant at approximately 30% above 1000 K. This loss is mainly generated by the thermal decomposition of the resin in CFRP. The activation temperature of CFRPs was estimated in this study. Therefore, the estimation of the mass loss in CFRP became possible.

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  The disposal of large amounts of sludge, deposited in many farm/irrigation ponds in Japan, has recently become an important task to be resolved. To dredge sludge helps to maintain the capacity of the ponds and the quality of the water in the pond. In other words, it is vital that the deposited sludge should be effectively dredged. Since the water content of dredged sludge is very high, it must be reduced to enable the transport and the reuse of the sludge. The authors of the present paper have developed a procedure to dehydrate in-situ dredged sludge from farm ponds using a compact filter press machine. The purpose of this study is to investigate appropriate conditions for the efficient dehydration of dredged sludge with a compact filter press machine. Since the dehydration mechanism inside the filter press machine is based on the hydraulic consolidation, hydraulic consolidation tests are conducted to simulate the filter press consolidation in order to clarify the relationship between the conditions of the filter press dehydration and the water content of the consolidated sludge. Results of the tests show that the most important factor in controlling the efficiency of the actual filter press dehydration process is the thickness of the filtration chamber of the filter press machine. Sludge is expected to be more effectively dehydrated when a filtration chamber with a smaller thickness is adopted.

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  We compared effects of different growing water potential conditions on physiological and morphological water–use properties of Sabina vulgaris Ant., which is an evergreen shrub that is widely distributed in arid and semi-arid environments of the Mu Us Sandy Land, China. Measurements were taken of cuttings grown for eight years under -0.02 MPa (control), -0.10 MPa (moderate water stress), and -0.34 MPa (severe water stress) water potential conditions. The transpiration rate (T_r) under moderate stress was significantly lower than that under severe stress and control water conditions (49% and 45% lower, respectively, than severe stress and the control on average). The leaf-specific hydraulic conductivity (LSC) in shrubs growing under moderate water stress was also significantly lower than for those under the severe water potential condition. In contrast, S. vulgaris growing under severe water stress had less leaf biomass than under moderate stress or control conditions. These results suggest that S. vulgaris growing under moderate water stress tends to show a reduced transpiration rate derived from its low LSC; therefore it avoids water loss in response to chronic water stress, while plants growing under severe water stress tends to reduce water loss through decreased leaf biomass. These results suggest that S. vulgaris has a high capacity for acclimation to different water potential conditions through physiological and morphological flexibility.

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  Numerical analysis of thermo-hydro-mechanical coupled finite element problems in fractured or porous media involves significant computational resources and parallel computing is a way to enable the use of the necessary computer power of SMP machines or clusters. An interdisciplinary collaboration is essential to port large scale and complex software applications efficiently to parallel platforms with shared or distributed memory. A comprehensive and continuously developed scientific software concept is required to treat the aspects of parallelization. We describe a resourceful and practicable software environment that enables the execution of serial or parallel applications, and which makes a transparent administration of the source code for a scientific group possible. Such software environments are difficult to design and implement, especially when solution adaptive techniques are used and three-dimensional problems on complex geometries are faced, which yield the use of unstructured meshes. In this paper, we present object-oriented software concepts and parallelization methods for serial/parallel runs and coupled/non-coupled schemes on single or multiple processes. Applications of different numerical simulations on different parallel computer platforms are described and compared to demonstrate the computational efficiency of the developed structures and procedures.

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  In this paper we present a numerical model for the simulation of non-isothermal air flow and corresponding heat transport in the unsaturated soil zone. The governing equations for non-isothermal gas flow and related heat transport are derived. The thermo-hydraulic (TH) coupling is additionally due to material properties, such as density, viscosity, heat diffusivity, which depends on the primary variables air pressure and temperature. A finite element model is developed for the solution of the resulting initial-boundary-value-problem. The numerical model is verified against analytical solutions for simplified problems. Finally, a case study for heat storage in soils is conducted.

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  Code comparison and benchmarking studies are important for testing the correct numerical implementation, especially in cases where analytical solutions for complex problems are not available. We will present results of such a code-comparison study for the calculation of matrix diffusion processes in fractured rocks. The benchmark investigates the accuracy of a new analytical solution which was recently introduced into the code GeoSys/RockFlow (GS/RF). We compared GS/RF with the well tested code PICNIC for advective-dispersive transport in a single fracture with constant aperture, advective-dispersive transport in a single fracture and additional matrix diffusion, and advective-dispersive transport in a single fracture plus matrix diffusion and linear sorption in the porous rock matrix. For all investigated cases the results of the two codes agree very well.

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  Argillaceous rocks are considered in Switzerland and in other countries as potential host rocks for the deep geologic disposal of radioactive waste. Opalinus Clay, a formation of Jurassic age, is at present the most favored candidate in Switzerland. It has a low hydraulic conductivity, no or only few active fractures, and a large retention capacity for sorbing solutes, which make this sediment well suited as an additional barrier for the spreading of contaminants. Transport through Opalinus Clay is typically dominated by diffusion. Accordingly, the diffusion of tracers through this material is intensively studied. In the underground research facility at Mont Terri in Switzerland, field experiments are performed that aim at investigating the diffusion and retention of sorbing tracers at intermediate scales and under relevant in-situ conditions. The field experiments use a borehole, from which tracers diffuse into the surrounding rock. The tracer cocktail in the borehole is continuously circulated, which allows to monitor the tracer decrease over time. When modeling these experiments, care has to be taken to correctly represent the inlet system. In this paper, it is shown how the numerical representation of the borehole and inlet system and the spatial discretization affect the simulation results of mobile and sorbing tracers. For mobile tracers, it is generally sufficient to use an effective diffusion coefficient for the circulated fluid about 30 times larger than that in the rock to mimic the continuous mixing. In contrast, for sorbing tracers even a 7000 times larger diffusion coefficient may, at early times, not lead to homogeneous borehole concentrations. This is because the equilibrium sorption on the rock quickly and drastically reduces the tracer concentrations at the interface. As a consequence, the simulated flux into the rock becomes too small, and the calculated average decrease of the borehole concentration is much too slow even for larger times. The slow decrease can be similar to that simulated for a much less sorbing solute, which of course would critically affect parameter estimation when fitting the model to observed data. Increasing the borehole diffusion coefficient to very large values to obtain a complete mixing can lead to a too fast simulated concentration decrease, if the spatial discretization is insufficient. Thus, a careful checking of the numerical results is required for the strongly sorbing tracers.

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