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The erosion of cohesive soils is regarded as one of the major threats to the failure of earth structures. The current evaluation of clay erodibility is primarily based on empirical correlations with other physical and mechanical soil properties, which lack a fundamental understanding of multiscale resistance formation under complicated environmental conditions. In this study, the hole erosion test (HET) was conducted using our augmented testing system, which includes sample preparation equipment and a temperature control unit. The kaolinite specimen is prepared following the saturated preconsolidation approach under defined stresses, which significantly improves the test repeatability. In total, 33 specimens are prepared and tested using the enhanced HET system under varying preconsolidation pressures, temperatures, and fines contents with triplicates for each case. The erosion resistance of clay increases with the preconsolidation pressure, and macropores are destructed into micropores, as revealed by the mercury intrusion porosimetry (MIP) test and the specific surface area analyzer. The scanning electron microscopy (SEM) images indicate an anisotropic aggregate structure prepared using the preconsolidation approach, which possesses different erodibility indices in different flow directions. With the increase in temperature from 10 degrees C to 40 degrees C, the critical shear stress decreases from 292 to 131 Pa (or by 55.1%). The addition of quartz sands in the kaolinite clay undermines the soil erosion resistance.

期刊论文 2025-06-01 DOI: 10.1061/IJGNAI.GMENG-10504 ISSN: 1532-3641

An experimental study was carried out to understand the physico-chemical and mechanical properties of marine clay reconstituted with different pore fluids. Three different pore fluids namely distilled water, 0.4 M NaCl and 1.0 M NaCl solutions, and 0.4 M CaCl2 solution were used in this study. The specimens were prepared using a 1D slurry consolidation technique at 50 kPa vertical pressure. This paper mainly includes the microstructural studies conducted using Scanning electron microscopic (SEM) images and Mercury intrusion porosimetry (MIP) tests. Furthermore, cyclic triaxial and resonant column tests were carried out on the marine clay specimens reconstituted with 0.4 M NaCl and 0.4 M CaCl2 solutions subjected to different confining pressures. The experimental results illustrated that with an increase in concentration of pore fluid the cyclic properties of reconstituted Chennai marine clay increases for strain amplitude varying between 0.001 and 1%.

期刊论文 2025-04-15 DOI: 10.1007/s40098-025-01215-5 ISSN: 0971-9555

Mercury is a significant environmental pollutant and public health threat, primarily recognized for its neurotoxic effects. Increasing evidence also highlights its harmful impact on the cardiovascular system, particularly in adults. Exposure to mercury through contaminated soil, air, or water initiates a cascade of pathological events that lead to organ damage, including platelet activation, oxidative stress, enhanced inflammation, and direct injury to critical cells such as cardiomyocytes and endothelial cells. Endothelial activation triggers the upregulation of adhesion molecules, promoting the recruitment of leukocytes and platelets to vascular sites. These interactions activate both platelets and immune cells, creating a pro-inflammatory, prothrombotic environment. A key outcome is the formation of platelet-leukocyte aggregates (PLAs), which exacerbate thromboinflammation and endothelial dysfunction. These processes significantly elevate cardiovascular risks, including thrombosis and vascular inflammation. This study offers a comprehensive analysis of the mechanisms underlying mercury-induced cardiotoxicity, focusing on oxidative stress, inflammation, and cellular dysfunction. [GRAPHICS] .

期刊论文 2025-03-01 DOI: 10.1007/s12012-025-09966-6 ISSN: 1530-7905

Heavy metal(loid)s (HM) pollution in aquatic environments is a serious issue due to the toxicity, persistence, bioaccumulation, and biomagnification of these pollutants. The main sources of HM contamination are industrial activities, mining, agricultural practices, and combustion of fossil fuels. Fish can accumulate HMs through a process called bioaccumulation. As larger predatory fish consume smaller fish, these HMs enter the main food chains and can become increasingly concentrated in their tissues and finally reach humans. Here, we provided a general and concise conclusion from current research findings on the toxicological effects on different body systems. Exposure to HMs can lead to a range of adverse health effects, including neurological damage, developmental disorders, kidney damage, cardiovascular problems, and cancers. Their long-term accumulation can result in chronic toxicity even at low levels of exposure. HMs exert cellular cytotoxicity by disrupting essential cellular processes and structures. They can interfere with enzyme function, disrupt cell membrane integrity, induce oxidative stress, and cause DNA damage, ultimately leading to cell death or dysfunction. Prevention and control of HMs involve implementing measures to reduce their release into the environment through regulations on industrial processes, waste management, and pollution control technologies. Additionally, monitoring and remediation efforts are crucial for identifying contaminated sites and implementing strategies such as soil and water remediation to reduce human exposure and mitigate the impact on ecosystems. To conclude, HM accumulation in fish poses serious risks to public health and the environment, necessitating urgent interdisciplinary efforts to mitigate their harmful effects and promote sustainable practices that reduce HM flow into biological systems.

期刊论文 2025-01-01 DOI: 10.4081/ijfs.2024.12782 ISSN: 2239-7132

Indian monsoon circulation is the primary driver of the long-range transboundary mercury (Hg) pollution from South Asia to the Himalayas and Tibet Plateau region, yet the northward extent of this transport remains unknown. In this study, a strong delta Hg-202 signature overlapping was found between Lake Gokyo and Indian anthropogenic sources, which is an indicative of the Hg source regions from South Asia. Most of the sediment samples were characterized with relatively large positive Delta Hg-199 values (mean = 0.07 parts per thousand-0.44 parts per thousand) and small positive Delta Hg-200 values (mean = 0.03 parts per thousand-0.08 parts per thousand). Notably, the Delta Hg-199 values in the lake sediments progressively increased from southwest to northeast. Moreover, the Delta Hg-199 values peaked at Lake Tanglha (mean = 0.44 parts per thousand +/- 0.04 parts per thousand) before decreased at Lake Qinghai that is under the influence of the westerlies. Our results suggest that transboundary atmospheric transport could transport Hg from South Asia northwards to at least the Tanglha Mountains in the northern Himalaya-Tibet.

期刊论文 2024-12-01 DOI: http://dx.doi.org/10.1029/2022GL100948 ISSN: 0094-8276

To satisfy the economic requirements and reduce the impact to the surrounding buildings and underground structures, the dynamic compaction (heavy tamping) and static compaction are combined used in the soil filling for airport subgrade. Despite compaction the subgrades in the same degree of compaction, the subgrades filled by dynamic and static compaction method show different increase potential in the permanent strain under cyclic loading, which then further result in the differential settlement and safety problems. This study firstly investigated the compaction characteristics under static compaction and different dynamic compaction scheme, during which the static and dynamic compaction strain and stress evolutions were monitored. The cyclic triaxial tests were then performed to investigate the sample preparation method derived difference in permanent strain under cyclic loading. Furthermore, to provide a microscopic interpretation to this difference, the pore size distributions of the silt samples based on mercury intrusion porosimetry (MIP) test and the internal particle contact stresses from discrete element method (DEM) simulation were respectively explored. The main conclusions are as follows: (1) The dynamic compaction processes can be divided into rapid and slow compaction strain stages determined by strain growth rate and compaction numbers, which further influences the homogeneity of soil samples; (2) The statically compacted samples have more significant permanent strain than the dynamic ones due to the localized stress concentration and different pore microstructures; the permanent strain increases with dynamic compaction energy until a stable stage is reached. (3) The MIP results show that the dynamic compaction transforms the macropores into mesopores; the higher compaction energy enhances this transforming effect but results in a decrease in the overall homogeneity.

期刊论文 2024-11-01 DOI: 10.1016/j.trgeo.2024.101378 ISSN: 2214-3912

Mercury ion (Hg2+) is one of the most toxic pollutants that can exist throughout the environment and be diffused into water, soil, air, and eventually the food chain. Even a very low level of Hg2+ diffused in living organisms can hurt their DNA and cause the permanent damage of the central nervous system and a variety of consequential disorders. Hence, the development of a sensitive and specific method for the detection of Hg2+ at trace ranges is extremely important as well as challenging. Fluorometric detection assays based on graphene quantum dots (GQDs) and carbon quantum dots (CQDs) offer considerable potential for the determination and monitoring of heavy metals due to their fascinating properties. Although the quantum yield of GQDs and CQDs is sufficient for their use as fluorescent probes, doping with heteroatoms can significantly improve their optical properties and selectivity toward specific analytes. This review explores the primary advances of CQDs and GQDs in their great electronic, optical, and physical properties, their synthetic methods, and their use in Hg2+ fluorimetry detection.

期刊论文 2024-09-01 DOI: 10.3390/photonics11090841

Mercury (Hg) is one of the most toxic global pollutants of continuing concern, posing a severe threat to human health and wildlife. Due to its mobility, Hg is easily transported through the atmosphere and directly deposited onto water, sediments and soils or incorporated in biota. In groundwater, Hg concentrations can be influenced by either geogenic or anthropogenic sources, causing critical health effects such as damage to the respiratory and nervous systems. The geogenic sources of Hg include rocks and minerals containing Hg (cinnabar, organic-rich shales, and sulfide-rich volcanic) and geothermal fluids. The anthropogenic Hg sources include the combustion of fossil fuels, gold mining, chemical discharges from dental preparation, laboratory activities and legacy sites. In groundwater, the average background concentration of Hg is < 0.01 mu g/L. Mercury can be mobilized into groundwater from geogenic or anthropogenic sources due to changes in redox potential (Eh), with concentrations reaching above the WHO drinking water standard of 1 mu g/L. Under reducing conditions, microbial activity facilitates the reductive dissolution of FeOOH, causing the release of sorbed Hg2+ into groundwater. The released Hg2+ may be reduced to Hg-0 by either dissolved organic matter or Fe2+. The stability of Hg species (Hg-0, Hg-2(2+), Hg2+, MeHg) in groundwater is controlled by Eh and pH. While high Eh and low pH conditions can mobilize Hg from the solid into aqueous phases, the soil binding ability can sequestrate the mobilized Hg via adsorption of Hg2+ by goethite, hematite, manganese oxides, hydrous ferric oxides, or organic matter restricting it from leaching into groundwater. During groundwater contamination, remediation using nanomaterials such as pumice-supported nanocomposite zero-valent iron, brass shavings, polyaniline-Fe3O4-silver diethyldithiocarbamate, and CoMoO/gamma-Al2O3 has been documented. These promising emerging technologies utilize the principle of adsorption to remove up to 99.98 % of Hg from highly contaminated groundwater. This study presents an overview of groundwater contamination, remediation, complex biogeochemical processes, and a hydrogeochemical conceptual model concerning Hg's mobility, fate, and transport.

期刊论文 2024-09-01 DOI: 10.1016/j.apgeochem.2024.106060 ISSN: 0883-2927

Soil improvement via cement-based stabilizers is often necessary to improve the workability and strength of problematic soils. However, understanding the underlying mechanisms of the stabilization process merits further study, particularly concerning changes in the microscale structure that affect macroscale behavior. Mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM) are often paired to characterize the microstructure and pore networks and can be used to quantitatively describe pore structure and surface complexity. Fractal geometry (e.g., fractal dimension and lacunarity) has been shown to provide a quantitative description of structural complexity in nature. Therefore, these fractal geometry fundamentals (fractal dimension and lacunarity) were implemented in the analysis of SEM micrographs and MIP results of a single-mineral kaolinitic soil (SA-1 kaolinite) stabilized with a portland cement stabilizer (portland cement Type I/II) to better understand the evolution of the soil microstructure with curing time. Particle size distributions (PSD) were developed based on image analysis of SEM micrographs collected at curing times of 1, 7, 14, 28, and 90 days. The surface fractal dimension obtained via analysis of MIP results was used to describe changes occurring in the pore network with curing time. The formation of cementitious products was inferred from changes in the PSD as gels first formed and then fused with clay surfaces. Box-counting fractal dimensions and lacunarity showed evidence of particle restructuring with cementation. The transition pore size between intraaggregate and interaggregate pores, obtained via fractal analysis of MIP data, decreased with curing time, indicating the formation of hydration products with stabilization. Using fractal geometry to help analyze the microstructural properties of stabilized clays may lead to better insight into their engineering scale behavior. Problematic soils pose an expensive problem to engineers and are often treated with cement-based stabilizers to improve strength and decrease compressibility or the potential to deform or collapse. However, the underlying mechanism causing problematic behavior, such as low strength or shrinking and swelling, is not well understood and techniques to characterize these soils at the microscopic level are needed to better prevent the damage posed to infrastructure. The current standard of practice utilizes only qualitative measurements of the soil structure and cannot be used in models attempting to predict clay behavior. Therefore, concepts from fractal geometry were used in this study to provide a quantitative, measured value of the soil and pore surface which can be used in future models. Analysis of images at the microscale provided a quantitative measurement of the change in soil structure as stabilization reactions occurred. Moreover, the geometric parameters obtained showed strong correlations with strength values, indicating the utility of the technique for predicting engineering behavior. The results of this study show promise for adapting the box-counting procedure to other, more complex soils. Additionally, because there was a good correlation between the fractal parameters and strength, the results should be correlated with other soil parameters.

期刊论文 2024-09-01 DOI: 10.1061/JMCEE7.MTENG-17391 ISSN: 0899-1561

The Qinghai-Tibet Plateau glaciers are an important carrier of mercury (Hg). With global warming, Hg enters into the downstream ecosystem in the melt waters, threatening human health and ecosystem security in the region. Methylmercury (MeHg), which has higher toxicity than Hg itself, is converted from inorganic Hg. However, little is known about the process of Hg methylation and, in particular, microbial Hg methylation in high altitude mountain glaciers. We combined Hg speciation measurements and metagenomic analysis of 6 sample types from the terminus of Laohugou No.12 glacier to elucidate potential microbially mediated Hg methylation. We found higher Hg concentrations in supraglacial cryoconite (SC) and dusty layer (DL) samples which contain considerable debris and dust. In addition, MeHg concentrations were highest in some of these SC and DL samples. Bacterial hgcA Hg methylation genes were present in all samples except supraglacial ice but were of highest abundance in SC and DL. This suggested that microbial Hg methylation is most likely to occur in SC and DL. There were 8 phyla of potential Hg methylation microorganisms, but 37% of the sequences could not be classified into any known genus. Most of the hgcA sequences were closely related to sequences from previously reported Hg methylating genera within the Deltaproteobacteria and Firmicutes, but the common Hg methylating Methanomicrobia were absent in glacial samples. (C) 2019 Elsevier B.V. All rights reserved.

期刊论文 2024-08-01 DOI: http://dx.doi.org/10.1016/j.scitotenv.2019.135226 ISSN: 0048-9697
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