Scaling effects on arsenic release from excavated hydrothermally altered rocks in column experiments

The excavation of hydrothermally altered rocks from construction sites in Japan has raised concerns over environmental pollution due to the arsenic (As) release beyond the regulatory limit. An accurate assessment of As leaching from these rocks is imperative to understanding potential environmental implications and formulating efficient containment measures. However, the conduction of column leaching experiments to evaluate As leaching from these rocks encounters a lack of well-established protocols primarily due to the ambiguity surrounding scaling effects resulting from alterations in particle sizes and the corresponding column dimensions. Our study aimed to address this critical issue by conducting column percolation experiments on hydrothermally altered rocks of two distinct particle size ranges and rock layer thicknesses. The pH value was found to be proportional to the specific surface area (SSA) of rocks and the rock layer thickness in terms of H+ concentrations. Furthermore, the concentration and leachability of As showed a similar proportionality with the SSA. In contrast, the concentration of As remained relatively unaffected by the increased rock layer thickness, while the leachability of As was noticeably diminished in the column with a thicker rock layer. The absence of elevated As concentration and the decrease in leachability can be attributed to the enhanced As onto Fe/Al oxyhydroxides/oxides within the half-bottom part of the column with a thicker rock layer. Our findings underscore the importance of considering the SSA of rocks and rock layer thickness in the column experiments and help in the design of effective strategies to mitigate environmental contamination.The version of record of this article, first published in Environmental Science and Pollution Research, is available online at Publisher’s website: https://doi.org/10.1007/s11356-023-30594-

Aging effects on the mechanical property of waste mixture in coastal landfill sites

AbstractCoastal landfill sites not only offer an option for disposal but also create a new land space after the completion of landfilling. To perform proper design on settlement, stability, and/or bearing capacity at landfill sites, the geotechnical properties of the waste layer such as deformation and shear strength should be investigated. This research is focused on the mechanical properties of waste mixture sampled at a coastal landfill site including municipal solid waste incinerator ash, slag, soil and others, to provide useful information on geotechnical properties in utilizing coastal landfill sites after their closure. A series of triaxial consolidated undrained compression tests (CU) and hydraulic conductivity tests were carried out on the reconstituted waste samples before and after being cured in simulated leachate water in coastal landfill sites for different periods, to understand the aging effects on mechanical properties of waste mixture. It was shown that while curing results in an increase in the peak strength and deformation modulus, the residual strength was not affected by the curing periods. Scanning electron microscope observations and X-ray diffraction analysis on the waste samples after curing confirmed that the formation of ettringite and hydration products had a densification effect on the microstructure. The higher peak shear strength and lower hydraulic conductivity of the waste samples were attributed to this effect

Multi-physics numerical analyses for predicting the alterations in permeability and reactive transport behavior within single rock fractures depending on temperature, stress, and fluid pH conditions

The aim of the current study was to establish a validated numerical model for addressing the changes in permeability and reactive transport behavior within rock fractures based on the fluid pH under coupled thermal-hydraulic-mechanical-chemical (THMC) conditions. Firstly, a multi-physics reactive transport model was proposed, considering the geochemical reactions that depend on the temperature, stress, and fluid chemistry conditions (e.g., fluid pH and solute concentrations), as well as the changes in permeability in the rock fractures driven by these reactions, after which the correctness of the model implementation was verified by solving the 1D reactive transport problem as a fundamental benchmark. Secondly, the validity of the model against actual rock fractures was investigated by utilizing the model to replicate the measurements of the evolving permeability and the effluent element concentrations in single granite fractures obtained by means of two flow-through experiments using deionized water (pH ∼ 6) and a NaOH aqueous solution (pH ∼ 11) as permeants under stressed, temperature-elevated conditions. The model predictions efficiently followed the changes in fracture permeability over time measured by both experiments. Additionally, the observed difference in the changing rates, which may contribute to the difference in the fluid pH between the two experiments, was also captured exactly by the predictions. Moreover, in terms of the effluent element concentrations, among all the elements targeted for measurement, the concentrations of most elements were replicated by the model within one order of discrepancy. Overall, it can be concluded that the developed model should be valid for estimating the changes in permeability and reactive transport behavior within rock fractures induced by geochemical reactions which depend on the fluid pH under coupled THMC conditions

Mean-field Coherent Ising Machines with artificial Zeeman terms

Coherent Ising Machine (CIM) is a network of optical parametric oscillators that solves combinatorial optimization problems by finding the ground state of an Ising Hamiltonian. In CIMs, a problem arises when attempting to realize the Zeeman term because of the mismatch in size between interaction and Zeeman terms due to the variable amplitude of the optical parametric oscillator pulses corresponding to spins. There have been three approaches proposed so far to address this problem for CIM, including the absolute mean amplitude method, the auxiliary spin method, and the chaotic amplitude control (CAC) method. This paper focuses on the efficient implementation of Zeeman terms within the mean-field CIM model, which is a physics-inspired heuristic solver without quantum noise. With the mean-field model, computation is easier than with more physically accurate models, which makes it suitable for implementation in FPGAs and large-scale simulations. Firstly, we examined the performance of the mean-field CIM model for realizing the Zeeman term with the CAC method, as well as their performance when compared to a more physically accurate model. Next, we compared the CAC method to other Zeeman term realization techniques on the mean-field model and a more physically accurate model. In both models, the CAC method outperformed the other methods while retaining similar performance.Comment: 8 pages, 4 figure

Effect of acidity on attenuation performance of sandy soil amended with granular calcium-magnesium composite

Utilising naturally contaminated soils and rocks is essential for significantly reducing geo-waste. However, there are no well-established concepts regarding the methods or countermeasures for utilising these soils and rocks, which would realise cost-effectiveness and environmental safety. Therefore, several researches focusing on the attenuation layer method have recently been undertaken. This method involves installing an attenuation layer between the contaminated materials and the ground to prevent ground contamination due to the attenuation capacity. A critical issue in the attenuation layer's design is to evaluate the attenuation performance of the layer material against target chemicals. Several important concerns and questions need to be solved when evaluating the attenuation performance. One is how the acidic leachate might diminish the layer material's attenuation performance. This paper presents the attenuation performance of a soil amended with a granular calcium-magnesium composite against acidic leachate. Batch and column tests, employing arsenic solutions of pH 2, 4 and 6, were applied to evaluate its attenuation performance. Using Freundlich parameter K as an index, the soil's attenuation performance was determined to have improved by at least 40% after the addition of the agent, even when the agent content was 5%. The amended soil's attenuation performance should be similar if the leachate pH is pH 6–4, although it might reduce by up to ~30% for pH 6. If the attenuation layer buffers the acid and provides the leachate with pH > 6, it will assure that the original ground's attenuation capacity is utilised. Considering this work's findings, amended soil can be employed as material for the attenuation layer

Evaluating the arsenic attenuation of soil amended with calcium–magnesium composites of different particle sizes

An attenuation layer composed of ground mixed with stabilising agents can prevent the contamination of the surrounding area when using soils and rocks with geogenic contaminants in embankments. The optimum particle size of the stabilising agent must be selected based on the requirements of the construction site because the mechanical and chemical properties of the attenuation layer are site-specific. However, the relationship between the particle size of the stabilising agent and the attenuation performance of soil–agent mixtures has yet to be fully clarified. This study employs batch sorption tests to evaluate the attenuation of arsenic by a soil mixed with a calcium–magnesium composite with different particle sizes, ranging from powder particles (<0.075 mm in size) to granular particles with diameters between 2.0 and 9.5 mm. Amended soil more effectively attenuates the contaminant than the original soil. In one experiment, a stabilising agent of granular particles (between 2.0 and 9.5 mm) for the amendment increased the soil’s partition coefficient Kd from 14.5 to 22.2 cm³/g, which is more than a 50% improvement in the attenuation. Using a stabilising agent with a smaller particle size for the amendment has a greater impact. Kd increases linearly as the particle size of the stabilising agent decreases down to 0.075 mm. Using the Kd from laboratory tests, simulations with a one-dimensional advection–dispersion equation demonstrate the durability of the attenuation layer. Both the powder and the granular particles show promise as attenuation layer materials

Fabric effect on hydraulic conductivity of kaolin under different chemical and biochemical conditions

AbstractA reasonably less permeable compacted clay liner (CCL) is critical to the long-term safety of waste containment facilities. This study experimentally investigates a variety of factors, including salinity, pH, fluctuation in permeant, permeation duration and presence of microorganisms, that are found to influence the hydraulic conductivity (k) of consolidated kaolin and the fabrics of suspended kaolin. Amongst these factors, a reduction in hydraulic conductivity of up to 4 orders of magnitude is obtained from the modification of the microfabrics of kaolin; a reduction of 2 orders of magnitude is brought about by bioclogging; a reduction of 1 order of magnitude is related to the concentrated Ca solution (>10mM). The hydraulic conductivity of consolidated kaolin can obviously be changed by adjusting the fabrics of the kaolin particles, e.g., clogging the pore spaces with bioslurry, permeating them with alkaline solution, or transforming the kaolin into metakaolin. An effluent pH larger than the isoelectric point (pHIEP) leads to a rapid reduction in k until 1×10–11m/s. A 3-dimensional fabric map was established for kaolin suspension in contact with a wide range of Ca concentrations and pH levels. The fabrics of kaolin suspension are predominated by a salt concentration (C>2.0mM) and a pH solution (C<2.0mM), respectively

Case Reports of TFE3-Rearranged Renal Cell Carcinoma: FDG-PET Uptake Might Help Diagnosis

Translocation and transcription factor E3 (TFE3)-rearranged renal cell carcinoma (RCC) is a rare subtype of RCCs characterised by the fusion of the TFE3 transcription factor genes on chromosome Xp11.2 with one of the multiple genes. TFE3-rearranged RCC occurs mainly in children and adolescents, although middle-aged cases are also observed. As computed tomography (CT)/magnetic resonance imaging (MRI) findings of TFE3-rearranged RCC overlap with those of other RCCs, differential diagnosis is often challenging. In the present case reports, we highlighted the features of the fluorine-18-labelled fluorodeoxyglucose positron emission tomography with CT (FDG PET-CT) in TFE3-rearranged RCCs. Due to the rarity of the disease, FDG PET-CT features of TFE3-rearranged RCC have not yet been reported. In our cases, FDG PET-CT showed high standardised uptake values (SUVmax) of 7.14 and 6.25 for primary tumours. This might imply that TFE3-rearranged RCC has high malignant potential. This is conceivable when the molecular background of the disease is considered in terms of glucose metabolism. Our cases suggest that a high SUVmax of the primary tumour is a clinical characteristic of TFE3-rearranged RCCs

evelopment of "SDGs Shiny Mudball (dorodango)" for teaching "Sustainable and contribution" and achievement of SDGs 4.7

There are few learning materials that can read the history (archive) carved in the soil and mud, look over disaster prevention education and geo-environmental problems in a single relationship diagram, and feel the feeling of the palm. Recognizing geo-environmental problems, experiencing soil and mud, revering soil and mud, and cultivating a "heart that cherishes the earth" means a skill necessary to achieve sustainable development involving SDGs. The authors conducted research and development using industrially adjusted pottery clay to make a learning material for visiting lecture using Shiny Mud Ball to achieve Sustainable Development Goals (SDGs). "SDGs Shiny Mud Balls" certainly enable everyone to get excitement and pleasure that shine or polish is obtained in a short period of time. "Contribution" of the SDGs can be understood by "SDGs Shiny Mud Balls"

Proteasomal degradation of BRAHMA promotes Boron tolerance in Arabidopsis

High levels of boron (B) induce DNA double-strand breaks (DSBs) in eukaryotes, including plants. Here we show a molecular pathway of high B-induced DSBs by characterizing Arabidopsis thaliana hypersensitive to excess boron mutants. Molecular analysis of the mutants revealed that degradation of a SWItch/Sucrose Non-Fermentable subunit, BRAHMA (BRM), by a 26S proteasome (26SP) with specific subunits is a key process for ameliorating high-B-induced DSBs. We also found that high-B treatment induces histone hyperacetylation, which increases susceptibility to DSBs. BRM binds to acetylated histone residues and opens chromatin. Accordingly, we propose that the 26SP limits chromatin opening by BRM in conjunction with histone hyperacetylation to maintain chromatin stability and avoid DSB formation under high-B conditions. Interestingly, a positive correlation between the extent of histone acetylation and DSB formation is evident in human cultured cells, suggesting that the mechanism of DSB induction is also valid in animals