White precipitates, formed when acid mine drainage (AMD) mixes with unpolluted stream water, consist mainly of basaluminite, an amorphous aluminum hydroxysulfate mineral, which plays a crucial role in controlling heavy metal behavior in aquatic systems. While previous studies have primarily investigated phase transformation in simple distilled water-based systems, research on mineralogical changes and heavy metal behavior in environments with high sulfate concentrations, such as actual AMD, remains limited. In this study, white precipitates collected near the Dogye mine were mixed with actual AMD, and reaction experiments were conducted at 75 degrees C with the pH adjusted to 6.0 and 8.0. The results indicated that at pH 6.0, the phase transformation from basaluminite to pseudoboehmite was dominant; during this process, the concentrations of most heavy metals decreased over time due to mechanisms such as adsorption, whereas Cu showed a tendency to increase due to re-dissolution. Conversely, at pH 8.0, heavy metal concentrations were generally lower due to adsorption resulting from surface charge changes caused by the pH increase. Furthermore, in addition to pseudoboehmite, the formation of manganese oxides (buserite, birnessite) and Mg-Al minerals (hydrotalcite, brucite) was confirmed. Over time, at pH 8.0 heavy metal concentrations showed different trends compared to pH 6.0, which is attributed to the formation of these specific minerals. These findings suggest that raising the pH to 8.0 or higher for the treatment of AMD containing Al and various cations can induce the formation of diverse secondary minerals, thereby effectively immobilizing heavy metals.
In this study, weathering induced changes in the pore size distribution(PSD) of sedimentary rocks were quantitatively analyzed using the N2 gas adsorption method. Shale and sandstone samples collected from the Jinju and Hasandong formations in the Sindong Group of the Gyeongsang Supergroup were subjected to six-month leaching experiments using peristaltic pumps. Water absorption ratios and FE-SEM observations obtained after the weathering experiments were compared with those measured prior to weathering. Based on the adsorption-desorption isotherms derived from N2 gas adsorption measurements, the BET, BJH, and HK methods were applied to evaluate PSD characteristics across different pore classes. The results indicate that shale, which generally exhibits a larger specific surface area, is more sensitive to weathering than sandstone. Furthermore, even within the same lithology, PSD patterns varied depending on intrinsic rock properties. These findings demonstrate that not only lithology but also inherent characteristics, such as mineral composition and grain size, play important roles in controlling weathering-induced changes in PSD. In addition, the discrepancies observed between changes in total pore volume estimated using N2 gas adsorption method and changes in water absorption in some shale samples are interpreted as limitations of the gas adsorption method, which is not suitable for measuring macropores.
We report a Quaternary fault developed in the southern part of the Yangsan Fault, Korea. The fault displace unconsolidated conglomerates on a slope developed in the river terrace around Samsu-ri, Yangsan, Korea. The unconsolidated conglomerates cut by the fault are the conglomerates derived from Tongdosa area and are mainly composed of granitic and andesitic boulders with a diameter of 5-30 cm. The fault strikes the north-south and dips to the east with high angles. The fault shows apparently the top-up-to-the-east reverse faulting geometry. However, two different slickensides with slip senses observed near fault surfaces indicate a dextral shearing with a reverse-slip component firstly during Quaternary and a dextral strike-slip movement lately. The vertical separation of the fault calculated from the offset of the different layers of unconsolidated sediments and basement, were estimated to be about 7 m.
This study explores soil contamination linked to ASGM activities in the Atiwa Forest area, southern Ghana, employing an integrated geochemical, multivariate, and probabilistic methodology. Sixty-four soil samples were analysed for As, Cd, Cr, Hg, Pb, and Zn through aqua regia digestion, with measurements taken using inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Pollution indices, Spearman correlation, self-organising maps (SOM), and Monte Carlo-based human health risk assessments were utilised. Average concentrations followed this order: Cr (250.10 mg/kg) > Zn (16.52 mg/kg) > As (15.76 mg/kg) > Pb (7.10 mg/kg) > Hg (0.47 mg/kg) > Cd (0.34 mg/kg). Arsenic and chromium showed widespread enrichment, with 82.8% of samples exceeding upper continental crust benchmarks. Cadmium and mercury displayed extreme variability, suggesting localised point-source contamination associated with ASGM practices. SOM analysis revealed two primary contamination regimes, distinguishing a geogenic Cr-rich domain from a mixed-source assemblage characterised by co-enrichment of As, Cd, and Hg. This assemblage reflects a geogenic arsenic background linked to Birimian gold mineralisation, locally intensified by artisanal mining activities such as sulphide oxidation, tailings leachate, and mercury amalgamation. Ecological risk assessment identified As, Cd, and Hg as the principal risk factors, with around 22% of samples categorised as presenting very high ecological risk (RI > 600). MERMQ results further confirmed the existence of localised zones with high probabilities of adverse biological effects. Probabilistic human health risk assessments indicated significant non-carcinogenic risks, with 45.02% of adult and 98.26% of child exposure scenarios exceeding the hazard threshold. Carcinogenic risk remained generally acceptable for adults but was unacceptably high for children, with maximum simulated values reaching 0.16. Overall, ASGM activities have increased metal mobility and exposure risks in the Atiwa Forest area, raising serious ecological and public health concerns, especially for children.
This study presents an integrated petrographic, mineralogical, and geomechanical evaluation of granitoid rocks, including granodiorite, granite, pegmatite, and aplite, from the Kohistan and Karakoram "Batholiths" exposed in the Nomal and Hunza regions of the Western Himalayas, Northern Pakistan. Granodiorites from the Nomal area exhibit hypidiomorphic granular textures and are primarily composed of quartz, plagioclase, orthoclase, perthite, and microcline, with accessory minerals including biotite, hornblende, zircon, and monazite. Granites display a comparable mineral assemblage, with additional features such as deformation fabrics and metamorphic overprints, suggesting tectonothermal reworking. The presence of xenoliths, thermal metamorphism, and mylonitization within these granitoids supports a complex postemplacement history. Trace amounts of malachite and visible native gold point to hydrothermal or possibly syngenetic mineralization processes. Geomechanical analyses indicate that Nomal granite possesses high uniaxial compressive strength (UCS), low porosity, high specific gravity, and low water absorption, making it suitable as a durable dimension stone for structural applications. In contrast, the granodiorite exhibits relatively higher porosity and lower UCS, which limits its suitability for load-bearing applications but makes it more suitable for nonstructural uses. The enrichment of accessory minerals such as zircon, monazite, titanite, and apatite in the granodiorite highlights its potential for "rare earth elements (REEs)" exploration. Overall, the results demonstrate the dual economic importance of the studied granitoids as both sources of strategic mineral resources and high-quality construction materials. Further, multidisciplinary investigations are recommended to comprehensively evaluate the mineralization potential and guide future development of quarry sites in the region.
This study integrates the results of the National Aggregate Resources Investigation (2007-2024) to quantify the reserves (approximately 9.93 billion m(3)), developable amounts (approximately 2.45 billion m3), and economic value (approximately 37.4 trillion KRW) of alluvial (river + land) aggregate resources across Korea, and to characterize the spatial mismatch between aggregate endowment and demand at the municipal level. A quadrant analysis comparing the survey data from 122 municipalities (covering 77.2% of the national alluvial deposit area) with 2018 ready-mixed concrete shipments reveals that 14 demand-dependent municipalities concentrate approximately 52% of total concrete demand yet possess virtually no alluvial aggregate reserves. Meanwhile, the share of alluvial aggregates in total extraction halved from 4.2% (2017) to 2.1% (2024), and the current supply structure-where crushed and screened aggregate and forest aggregates account for 89% of total production-entails structural uncertainties related to construction-cycle dependency and prolonged permitting processes. Although transport distance constraints (mean 6 km) preclude alluvial aggregates from serving as a broad-scale supply regulator, this study demonstrates that alluvial deposits in 20 potential-resource municipalities can function as local buffer resources within a 20-50 km service radius. These findings provide baseline data for regional-scale aggregate resource management under structural supply uncertainties.
Critical mineral development involves not only resource availability but also policy coordination and governance challenges across the supply chain. This study examines how stakeholders' policy perceptions shape the demand for a coordination body in domestic critical mineral development in Korea. Using survey data from 515 respondents representing various segments of the critical mineral value chain and related policy communities, the study employs partial least squares structural equation modeling (PLS-SEM) to analyze the structural relationships among key perception variables. The results indicate that perceptions of the necessity of domestic development and recognition of structural problems in the current system significantly strengthen perceptions of the need for policy and institutional reform. These policy perceptions, in turn, increase support for government policy measures and supply-chain strategies, including international cooperation and domestic capability building. Both factors significantly increase the perceived need for a coordination body to align policy instruments and value-chain strategies. Additional robustness analysis shows that preferences regarding the actor responsible for project implementation do not directly influence this governance demand. By conceptualizing policy perception as a sequential and structural process - spanning problem diagnosis, institutional reform demands, policy instrument preferences, and governance needs - this study advances beyond approaches that treat policy perceptions as parallel, independent attitude variables. These findings suggest that a coordination body is demanded primarily as an institutional mechanism to integrate policy instruments and supply-chain strategies rather than as a reflection of actor preferences in critical mineral development.
In South Korea's national aggregate supply-demand planning, ready-mixed concrete (RMC) shipment has served as the key indicator for estimating aggregate demand; however, the conversion factor alpha = 1.25 (Lee and Hong, 2021; Lee et al., 2024) used to translate RMC shipment volume into aggregate volume was a conventional volume coefficient, overestimating aggregate demand by approximately 11%. Furthermore, because the accuracy of this conversion factor (alpha) had not been verified, assessments of aggregate supply-demand balance lacked sufficient reliability. This study therefore re-derives the aggregate bulk-volume conversion factor alpha per 1 m(3) of RMC for supply-demand balance assessment, using standardized RMC shipment data. Strength-class distributions of government-procured RMC (2018-2024) were calculated from transaction records of the Korea ON-line E-Procurement System (KONEPS), yielding alpha = 1.13 (CV = 0.53%) based on the KS F 4009 strength classification combined with KONEPS mix-design data. This value matches the lower bound of the American Concrete Institute (ACI) 211.1 theoretical range (1.13-1.30), confirming consistency with internationally accepted figures. Independent cross-validation using domestic cement shipment data also confirmed the consistency between the two datasets, with a discrepancy of only-5.8% between cement-derived RMC volume and association-reported shipment. Consequently, revising alpha from 1.25 to 1.13 raises the national aggregate sufficiency rate from 73.5% to 81.3%; yet the rate remains below 100%, confirming that the previously reported "supply surplus" assessment should in fact be characterized as "actual deficit in the market places." These findings provide a basis for reestablishing the demand estimation framework underlying national aggregate supply-demand planning, although further investigation is needed to identify the specific causes of this supply-demand gap.
This study investigated the removal efficiency of heavy metals from highly contaminated synthetic acid mine drainage and characteristics of precipitates formed after reaction using Ca-Mg-based carbonate and hydroxide minerals under calcined and uncalcined conditions. The reaction media included CaCO3, Ca(OH)(2), MgCO3, and Mg(OH)(2), and their reaction characteristics were compared with those of CaO and MgO produced by calcination at 800 degrees C. Heavy metal removal experiments were conducted under batch reaction conditions, and changes in pH and concentrations of Cd, Cu, Fe, Mn, and Zn were analyzed as a function of reaction time. In addition, X-ray diffraction (XRD) and thermogravimetric-differential thermal analysis (TG-DTA) were performed to evaluate the mineralogical and thermal characteristics of the media and reaction products before and after calcination. Among the uncalcined media, Ca(OH)(2) exhibited the highest pH increase (pH > 12) and showed high removal efficiency for most heavy metals. The calcined media exhibited faster pH increase and enhanced heavy metal removal efficiency compared to the uncalcined media. Under conditions with sufficient sulfate (SO4), gypsum (CaSO4 & centerdot;2H(2)O) was formed as the dominant precipitate in the Ca-based media, indicating sulfate immobilization, whereas no sulfate minerals were formed in the Mg-based media, and hydroxide or carbonate minerals were predominantly formed.
The Iksan Ssangneung (Twin Tombs), a historic site comprising the Daewangneung (Great Royal Tomb) and the Sowangneung (Small Royal Tomb), are typical stone chamber tombs from the Baekje Sabi Period. The stones from the Sowangneung are all light gray biotite granite with a medium-grained texture. While the stones are generally the same in occurrences, lithology and textural characteristics, some stones exhibit subtle differences in grain size, arrangement and content of biotite. Searching for the provenances of the stones revealed that the granite body at the Mt. Mireuksan exhibits diverse quarrying traces. Based on geographic location, distance and geochemical homogeneity, this is believed to be the provenance of the Sowangneung stones. Petrological and geochemical analyses of the granitic rocks collected from the Sowangneung and the presumed source area revealed nearly identical major element compositions, but some trace and rare earth element trends differed slightly. This suggests that all granite specimens originated from the same magma, but with partial differences in their differentiation pathways. While quarrying is currently impossible in the Mt. Mireuksan, granite from the Hwangdeung area continues to be produced, and its petrological and geochemical characteristics are nearly identical. Therefore, granite from the Hwangdeung Quarry could serve as a replacement for the stonework of the Sowangneung.
The performance of commonly used single-extraction methods for evaluating the stabilization efficiency of heavy metals in stabilized soils was compared. Agricultural soil near an abandoned metal mine was treated with a limestone-steel slag mixture and oak-derived biochar. After stabilization, the leaching behavior of As, Pb, Zn, Cu, Cd, and Ni was evaluated using five single-extraction methods: 0.1 N HCl, 1 N HCl, Mehlich-3, CaCl2, and TCLP. The results showed that soils stabilized with the limestone-steel slag mixture exhibited consistent reductions in extractable concentrations of all tested metals when assessed using 0.1 N and 1 N HCl. In contrast, Mehlich-3, CaCl2, and TCLP revealed stabilization effects only for specific metals. Arsenic stabilization was effectively detected only by inorganic acid extractions, whereas Zn and Cd also showed measurable stabilization under CaCl2 extraction. For biochar-treated soils, stabilization effects were observed primarily when extracted with 0.1 N HCl, while CaCl2 extraction indicated stabilization only for Zn. Other extraction methods failed to detect meaningful stabilization for most metals. The results suggest that, under the conditions of this study, the stabilization effectiveness of the oak-derived biochar used in this experiment may be limited compared to that of the alkaline limestone-steel slag mixture. Overall, the results demonstrate that the evaluation of stabilization efficiency is highly dependent on the choice of leaching agent, as different extractants target distinct metal fractions in soil. This study indicates the necessity of selecting appropriate extraction methods based on the stabilizing agent and target metals when assessing post-treatment stabilization performance.
This study presents landslide susceptibility mapping (LSM) using frequency ratio (FR) and convolutional neural network (CNN) models in the South Bostanlyk area of Uzbekistan, a region that is highly susceptible to landslides due to steep mountainous terrain, complex geology, and active seismicity. The study area features carbonate bedrock overlain by loess and colluvial deposits, which exacerbate slope instability, particularly during seasonal rainfall and snowmelt events. This study aimed to systematically delineate areas susceptible to future landslides through an integrated analysis of geomorphological, geology, soil, normalized difference vegetation index (NDVI), land cover, and historical landslide inventory datasets. FR analysis revealed that landslide occurrence correlates strongly with valley depth, relative slope position, terrain ruggedness index, channel network distance, and land cover, while XGBoost feature importance confirmed valley depth, and relative slope position as the top two dominant factors. To complement this statistical approach, a CNN model was applied to the spatial datasets, resulting in improved predictive performance. Both the CNN and FR models achieved predictive accuracies exceeding 75%, confirming their robustness for regional-scale landslide susceptibility assessment. The resulting susceptibility maps offer practical insights for disaster risk management, infrastructure development, and climate change adaptation, highlighting the effectiveness of integrated modeling frameworks for landslide risk mitigation in rapidly developing mountainous regions such as the South Bostanlyk area.
Concentrations of heavy metals in highly contaminated groundwater samples collected from a smelter area and used in the removal efficiency experiments were Cd 153.34 mg/L, Cu 29.38 mg/L, Fe 4.63 mg/L, Mn 1150.16 mg/L, and Zn 10062.27 mg/L. The amount of precipitate formed increases proportionally with the amount of NaOH added to raise the pH. A total of 863 mL of 1 M NaOH was required to increase the initial pH from 3.32 to 11.30. The total amount of precipitate was 52.8 g, with 46.57 g formed in the pH range of 5.55 to 7.34. The color of the precipitate generally corresponds to Munsell color 10YR. Based on removal efficiency evaluation, the order of heavy metal removal from highly contaminated groundwater is Fe > Cu > Zn > Cd > Mn. X-ray diffraction analysis shows that minerals in the precipitates consist of kieserite (MgSO4 & centerdot;H2O), namuwite [Zn2Cu2(SO4)(OH)(6)& centerdot;4H(2)O], birnessite (MnO2 & centerdot;nH(2)O), hausmannite (Mn3O4), cadmium hydroxide [Cd(OH)(2)], thenardite (Na2SO4), and brucite [Mg(OH)(2)]. According to the MINTEQ modeling results, Zn precipitates as hydroxy-sulfate and hydroxide phases, Mn as sulfate phases, and Cd as hydroxy-sulfate and hydroxide phases.
