Geological Information Research Articles

Feasibility of Induced Magnetic Gradient Surveying for Seepage Detection in Earth-filled Dams: Insights from Synthetic and Field Studies

Seepage is a common hydrogeological hazard in engineering. Determining the seepage paths is vital for de-risking the instability of embankment structures. With the improvement of the acquisition accuracy of magnetic sensors, the magnetometric resistivity method has become an emerging technology for detecting seepage paths through earth-filled dams. This technique is non-destructive and gives prominent signals. However, the resulting magnetic data have seen ambiguity in fully determining the targets. We propose an induced magnetic gradient surveying approach to monitor seepage paths in earth-filled dams. First, we briefly review the electromagnetic theory for the magnetic gradient tensor based on Maxwell’s equations. To match against the measurements, we present an accurate modeling framework using the third-order finite element method and a novel compact difference scheme. We verify our approach on both semi-analytical 1D and 3D models. Systematic modeling studies are then carried out to investigate the spatial distribution characteristics and sensitivities of the induced magnetic gradient to the seepage in typical dam scenarios. In addition, we conducted two field experiments in the Zhongmou experimental base and Xixiayuan Reservoir in Henan Province, China,respectively. The induced magnetic field vector and its gradient components were both acquired. Cross-validation with a-priori geological information shows that the seepage path can be spatially identified by the induced magnetic gradient components Byy, Byz, Bzy, and Bzz while the field components failed to locate the seepage pathways. This successful application indicates that the proposed approach could be a promising solution for seepage path discrimination in earth-filled dams with high resolution.

Experimental investigation of the coupled effects of bedding planes and flaws on fracture evolution of soft bedded rocks based on 3D printing and DIC technologies

Bedded rocks are a typical geological formation with significant implications for understanding tectonic evolution, rock engineering, and geological hazard mitigation. This study introduces a novel method for fabricating bedded rocks using 3D printing (3DP) technology. By comparing the mechanical anisotropic properties and failure modes of 3DP bedded rocks with natural bedded rocks, we validate the feasibility of this approach. Compression tests are conducted on 3DP bedded rocks containing a single flaw to investigate the coupled effects of bedding planes and flaws on the mechanical properties. Digital image correlation (DIC) is employed for full-field deformation measurement during loading, enabling the study of deformation and crack evolution patterns. The results indicate that bedding planes dominate the brittleness of 3DP bedded rocks containing a single flaw. Significant plastic characteristics and prolonged nonlinear deformation stages are observed when the bedding angle (α) is between 0° and 45°, while brittleness becomes apparent beyond 45°. Both strength and elastic modulus are decided by bedding planes and initial flaws. By comparing stress–strain curves and rate of effective variance change (REVC)-strain curves, crack initiation can be quantitatively identified, revealing a linear correlation between strength and stress values at crack initiation points. The bedding plane also dominates crack propagation and failure modes: when α ≤ 30°, cracks propagate through the bedding, indicating tensile failure; when 45° ≤ α＜90°, cracks propagate along the bedding, indicating tensile-shear or shear failure; and when α = 90°, cracks propagate along bedding planes, indicating tensile failure. The findings of this study provide insights for explaining and predicting failure modes in engineering projects involving bedded rock formations, such as slopes, tunnels, and coal mines.

Hydrogeological assessment and aquifer potential of a coastal area, South Nigeria: insights from VES surveys and spatial analysis

ABSTRACT This study provides a comprehensive analysis of aquifer properties using vertical electrical sounding (VES) surveys conducted in Eket, Nigeria, to address the challenges of groundwater management in coastal areas. The VES method was employed for hydrogeo-electrical analysis and to investigate the hydrogeological dynamics of the region. The results reveal varying subsurface layers with distinct resistivity values. Spatial distribution analysis indicates densely settled areas exhibit lower resistivities, while sparsely settled regions show higher resistivities. The spatial location labeled EK2 features the largest aquifer, measuring 246.70 m, predominantly located in the central research area. Aquifer depths range from 87.10 to 250.20 m, with variations in thickness highlighting geographical heterogeneity and its impact on groundwater transport. These spatial differences in groundwater characteristics are crucial for understanding groundwater movement, storage, and extraction potential. The study underscores significant variability in porosity, reflecting differences in the aquifers’ water storage capacity and susceptibility to contamination. These findings have important implications for groundwater flow rates and extraction feasibility. The research provides essential data for hydrogeological investigations and groundwater resource management, emphasizing the intricate relationship among geological formations, aquifer properties, human activities, and the potential risks of contamination in variable porosity zones.

Three-dimensional model and environmental fragility in the Guarani Aquifer system, SE-Brazil

The Guarani Aquifer System (GAS) is a vast transboundary continental sedimentary basin in southern South America, encompassing sedimentary rocks and basalt flows across Uruguay, Paraguay, Argentina, and Brazil. It serves as a crucial water resource for urban supply and irrigation. This study aims to propose geophysical, geometric, and fragility models of the GAS in a critical exploitation area, utilizing geological data, geophysical logs, geomorphometry, and information from tubular wells. The models define distinct geophysical ranges for each formation and identify contacts between sedimentary and basaltic rocks. Integration of horizontal and vertical spatial distributions of geophysical and geological data forms a 3D model, revealing basaltic flows and intrusions distribution in fragile areas between formations, and potentially connecting aquifer layers. Natural fragility zones, characterized by high fracture densities, are observed in the central-east region, while outcrop and recharge areas of the main aquifer hydrofacies are found in the north. The 3D model highlights similarities between the topography of the Botucatu Formation (KJb – eolian sandstones) and the potentiometry of GAS at local scales, and overexploitation zones in Ribeirão Preto's city center. The assessment prioritizes areas at risk and conservation strategies for sedimentary aquifers, emphasizing interactions between surface and groundwater and addressing issues of overexploitation, identifying high-impact risks on GAS hydrodynamics and water quality.

Dynamic interaction of heavy metals and mineralogical shifts in stream sediments exposed to MSW landfill leachate in a semi-arid basaltic terrain

Investigating concentrations and spatial patterns of physicochemical parameters in landfill leachate and their profound impacts on stream sediments is an important issue for environmental sustainability. Therefore, the present study showed that the specifics landfill leachate and its interactions with stream sediments within the unique geological context of semi-arid basaltic terrain of the Deccan Volcanic Province in Pune, India. Employing advanced geo-accumulation indices and crystal phase differentiation methods, the study unveils the intricate metamorphosis of heavy metals and mineralogical composition, tracing the transformative journey from leachate to sediments. Noteworthy revelations emerge, particularly in the striking associations between heavy metals and the mineralogical composition, which encompasses primary and secondary minerals (calcite, quartz, and Fe–Mg oxides). These findings underscore the acceleration of weathering processes within this distinctive geological milieu. The 'geo-accumulation index' exhibits pronounced elevations in proximity to the landfill site, with persistence downstream, reliant upon the evolving weathering and accumulation dynamics. The lower reaches of the study area have higher concentrations of various heavy metals (Fe, Mn, Zn, Cr, Cu, Ni, Co, Hg, As, and Cd). These heavy metals are primarily sequestered within silt-dominated sediments conquered by augite, olivine and plagioclase minerals. Present research reveals the complex interplay between heavy metals in leachate and their physical and chemical interactions with sedimentary materials. These gradational shifts in mineralogy and geochemistry serve as compelling evidence of the transformative impact of leachate discharge within the distinctive basaltic geological framework. This study offers valuable insights into the complex environmental processes occurring at the intersection of landfill leachate and natural geological formations, enhancing the understanding of the dynamic geochemical interactions that shape this semi-arid basaltic terrain.

Mineralogical and geochemical composition of a cementitious grout and its evolution during interaction with water

In the present study, the chemical composition, mineralogy, and mechanisms of alteration of a cementitious grout based on a CEM III/C with addition of smectite, hydrotalcite, and silica fume, are studied using a combination of chemical and physical methods. This material was designed in the context of geological repository of radioactive wastes, with a twofold aim: first, to fill the technical voids left by drilling operations at the interface between the geological formation and the disposal galleries. Second, to neutralize a potential acidic transient due to pyrite oxidation, and to create an environment that favors low corrosion rates of carbon steels. The grout is mainly composed of calcium silicate hydrates having a Ca/Si ratio of ~0.8, incorporating Al in the bridging site of the Si chains (C-A-S-H), and accounting for 29–36 wt.% of the sample. It also contains silica fume (38–48 wt.%), smectite with interlayer Na (11–17 wt.%), hydrotalcite with interlayer CO32− (3–4 wt.%), and lower amounts of portlandite, calcite, and possibly gibbsite and gypsum. Upon alteration by water in a flow-through reactor, the main modifications affecting the sample are calcite and gypsum dissolution, hence releasing aqueous Ca2+ that is adsorbed in smectite interlayer by replacing Na+, and stoichiometric C-A-S-H dissolution. The evolution of solution chemistry and of the solid phase composition are reproduced successfully using a thermokinetic model.

A Numerical Study of Fault Reactivation Mechanisms in CO2 Storage.

Due to extensive industrialization and ongoing fossil fuel consumption, CO2 emissions have significantly contributed to climate change and rising greenhouse gas levels. The collection and storage of CO2 in subsurface geological formations have been proposed as a feasible alternative. The well-documented In Salah storage site is the subject of the chosen case study. For the numerical analysis, a two-dimensional finite element simulation of fault reactivation processes was conducted in the context of the CO2 storage. The goal of this research is to conduct a mechanistic numerical analysis of a typical CO2 storage condition. The selected analysis domain is 4 km (width) × 2 km (depth) and includes all important domains and formations (overburden, main caprock, lower caprock, and underburden) of the In Salah site. The simulation results indicate that the influence of fault reactivation under 32 MPa of base injection pressure results in peak vertical deformation of 0.044 m in the caprock and a vertical displacement magnitude of 0.015-0.020 m at the surface level (Z = 0 m). The derived vertical deformation findings at the surface level are in agreement with the data obtained from the in situ InSAR monitoring system in 2009. The effects of the changes in the fault dip angle, key caprock mechanical parameters, and in situ stress ratio on the displacement profile are evaluated within the parametric study. In comparison to the benchmark numerical run, the scenario ratio of k = 0.5 led to a significant reduction in the displacement. The simulation in which the fault dip angle was 30° produced a more pessimistic result with a larger displacement field. This could be an indication of heightened fault reactivation risks associated with low-angle faults in storage sites with strong horizontal stress regimes due to the combined effect of increased shear stress and reduced inherent frictional resistance on the fault plane. Considering that a vertical fault dip angle (90°) and an additional three 20 m long vertical fractures above the reservoir produced similar vertical displacement observed with the fault dipping at a 60° angle, this indicated that the vertical faults in the vicinity of the storage site pose limited safety risks to the integrity of the sealing rock.

Gravity Investigations Applied to the Geological Framework Study of the Mambasa Territory in Democratic Republic of Congo

This study concerns the gravity survey carried out in the territory of Mambasa in the province of Ituri in DR Congo, with the aim of studying its subsurface framework. We applied Free-Air and Bouguer corrections to the gravity measurements in order to eliminate gravity variations of non-geological origin. As for the graphical representation of the results, the spatial interpolation tools were useful to us in the elaboration of Bouguer anomaly maps. Then, we classified the study zone into Bouguer anomaly zones based on intensity. Gravity highs could indicate basement uplifts due to compressional movements. These uplifts would have led to the formation of granite domes which could be associated with mineralization. The enormous gravity depression would, for its part, be synonymous with a ditch or the presence of very low-density geological formations. The gravity profiles drawn support the analyzes of the maps: the anomaly curves are very fluctuating and uneven, highlighting several gravity highs and depressions. These fluctuations are probably induced by the presence of faults which separate the different anomaly zones.

Uncertainty modeling and propagation for groundwater flow: a comparative study of surrogates

We compare sparse grid stochastic collocation and Gaussian process emulation as surrogates for the parameter-to-observation map of a groundwater flow problem related to the Waste Isolation Pilot Plant in Carlsbad, NM. The goal is the computation of the probability distribution of a contaminant particle travel time resulting from uncertain knowledge about the transmissivity field. The latter is modelled as a lognormal random field which is fitted by restricted maximum likelihood estimation and universal kriging to observational data as well as geological information including site-specific trend regression functions obtained from technical documentation. The resulting random transmissivity field leads to a random groundwater flow and particle transport problem which is solved realization-wise using a mixed finite element discretization. Computational surrogates, once constructed, allow sampling the quantities of interest in the uncertainty analysis at substantially reduced computational cost. Special emphasis is placed on explaining the differences between the two surrogates in terms of computational realization and interpretation of the results. Numerical experiments are given for illustration.

CO2-Rock-Brine Interactions in Feldspar-Rich Sandstones That Underwent Intense Heating.

The success of any carbon capture and storage method largely depends on, among other factors, its safety, reliability, and thorough understanding of the interactions among CO2, underground geological formation, and resident brine. Upon injection into the subsurface rock formation, CO2 interacts with the host geological formation and brine, initiating complex geochemical reactions that are often poorly understood and could potentially affect the overall stability and storage capacity of the geological formation, particularly those in close proximity to an intense heat source. For instance, the impact of intense and prolonged heat due to, say, magmatic intrusion on sandstones' framework, authigenic mineralogies, and CO2-storage potentials is still poorly understood. Consequently, in this study, we have investigated the impact of firing on CO2-rock-brine reactions in the Bandera Gray (BG) sandstone. Prior to the CO2 injection using 60 000 ppm brine at 75 °C and 28.7 MPa for 30 days, two samples of the BG sandstone were fired for 6 h in a muffle furnace at 700 and 1100 °C each. The BG samples were then studied for XRD, SEM, and ICP-OES analyses before and after the CO2 injection, mainly to investigate any changes in mineralogical compositions and fluid chemistry. To determine the impact of the CO2-rock-brine interactions on the authigenic and framework mineralogies of the BG sandstones under low pH (∼3) conditions, powdered samples of the pre- and postfired BG sandstones were treated with nitric acid. The findings of the study indicate that there were no observable reactions involving rock-forming minerals and carbonate cement in the unfired and fired (at 700 °C) sandstones after the CO2 injection. However, pervasive feldspar-dissolution porosity was formed in the postfired BG sandstone (1100 °C) after CO2 injection. This was mainly because albite was partly to pervasively transformed into anorthite during firing at 1100 °C, making the feldspar highly susceptible to dissolution under CO2 conditions. This implies that the conversion of albite into chemically unstable anorthite in natural sandstones that underwent intense and prolonged heating could develop significant amounts of secondary dissolution porosity due to CO2 injection, thereby impacting their storage capacities and overall petrophysical properties. This dissolution was separately corroborated using a nitric acid treatment. The findings of the study will provide a better understanding of the CO2-rock-brine reactions involving sandstones that experienced intense heat due to, for instance, magmatic activity over a long geologic time scale, which has largely transformed the chemistry of their feldspars, particularly plagioclase.

Semi-supervised recognition of tunnel surrounding rock discontinuities using drilling jumbo data

Geological information ahead of the tunnel face is vital for ensuring safe and efficient tunnel construction. This paper presents a semi-supervised approach that combines a constrained dense convolutional autoencoder (CDAE) with a hybrid deep neural network (HDNN) to predict rock mass discontinuities. The factors related to rock mass discontinuity are categorized into four main classes: geometry, geology, construction, and measurement while drilling (MWD). The geological similarity between neighbouring blastholes is taken into consideration to constrain the training process of CDAE. These four categories of data serve as input parameters for CDAE-HDNN to predict rock mass discontinuity. Data from the Yangjiawopu tunnel is employed to assess the performance and generalization capability of the proposed method. The results show that CDAE can extract features related to rock mass discontinuity, and the proposed model exhibits superior performance and robustness compared to conventional deep learning and machine learning models.

Vertebrates from the Late Miocene of Salinas Grandes de Hidalgo (central Argentina). New faunal data: biochronological and paleoenvironmental considerations

ABSTRACT Salinas Grandes de Hidalgo (La Pampa Province) is a relevant locality of the Cerro Azul Formation in central Argentina because of its abundant and diverse vertebrate remains, including representatives of Reptilia, Aves and mostly Mammalia. Concerning previous records, the present faunal list adds one Argyrolagidae marsupial, one Ctenomyidae and two Caviidae rodents, as well as the first detailed analysis and description of glyptodonts from the Cerro Azul Formation in La Pampa Province. New geological information is added about the two fossiliferous outcrops included in Salinas Grandes de Hidalgo area. The classically studied outcrop located in the saline lake and the nearby one in the so-called ex-Autódromo, both herein correlated based on lithostratigraphy, particularly by the presence of paleosols in the intermediate section of the sedimentary succession. These sandy silts deposits in the base of the outcrops indicate the development of poorly confined flows and intervals of surface stabilisation by paedogenesis. We offer a biochronological interpretation based on a recently published U-Pb detrital zircons dating (5.9 ± 0.4 Ma) and the presence of significant taxa such as octodontoid rodents recovered from the dated levels and below it. From a paleoenvironmental viewpoint, we infer variations from woodlands to open environments.

A pragmatic approach of hydrochemical and irrigation indices of groundwater quality of district Ballia, U.P. India

ABSTRACT In the groundwater aquifer media, enormous amounts of ions can be found naturally in rocks from the Pleistocene and Holocene ages. There are several reports of metals and ionic contamination in the different blocks of the Ballia district. This article focuses on a thorough investigation of the hydrogeochemical properties and the cause of ionic contamination in the Ballia district's groundwater system. This article discusses the interactions between the numerous cations and anions that are hydro-geologically present as well as several physico-chemical factors. The relationship analysis was conducted utilizing irrigation indices and a Stufzand classification, which was further supported by a Durov and Stiff plot. The Durov plot shows the mineralization of the aquifer by sand and evaporates of geological formation. The Gibbs plot shows that the rock–water interaction, weathering of silicates, evaporates dissolution, carbonate dissolution, and anthropogenic activities. The Stiff plot shows the highest concentration of Mg-rich minerals and Cl due to the weathering of calcite, amphiboles, and anthropogenic activities also proven by the Irrigation indices and Stufzand classification. The high water quality index (WQI) value was discovered to be mostly due to greater EC, total dissolved solids, hardness, nitrate, sulfate, chloride, and magnesium levels in groundwater.

Формирование цифровой модели угольного месторождения в горно-геологической информационной системе МАЙНФРЭЙМ

Digitalization of enterprise management using Russian software is the main trend in the development of the country's mining sector. Sharp fluctuations in demand and prices in the mineral markets, as well as the development of technical tools for mechanization and automation of technological processes along with a systematic increase in their cost affect the financial performance of mining companies. This determines the need for a rapid adoption of technical, technological and organizational decisions, which, along with the requirements of the company's owners and regulators to obtain prompt, reliable and the most complete information about the production process explains the urgent need for the prompt introduction of digital control systems for mining operations. In the article the authors describe an algorithm to design a digital model of the mining and geological system, including a digital geological model of the deposit, digital models of mine workings and the surface topography, based on the experience of creating three-dimensional digital models of complex-structured coal deposits. The basic software suite for designing a digital management system for mining operations is the MINEFRAME mining and geological information system developed at the Mining Institute of the Kola Scientific Center of the Russian Academy of Sciences. MINEFRAME allows to perform a full range of tasks aimed at creation of a digital 3D model of the mining and geological system for a coal deposit with the possibility to account for the complex bedding in the modelling. High accuracy and correctness of the input geological sampling data is achieved by means of tools to check for errors in the tables of borehole collar coordinates, inclinometry and sampling. The wireframe modelling methods implemented in MINEFRAME provide the possibility to create wireframe models of seams with high detail in the fracture zones.

A critical meta-analysis of CO2-water-rock interaction in basalt for CO2 storage: A review based on global and Indian perspective

Global warming and energy security lead to the hunt for alternative energy sources and CO2 emission mitigation technologies like carbon capture and storage (CCS). CCS is a prominent technique and its success depends on the sites of storage and agents influencing the storage efficiency. Geological formations are much safer as compared to oceanic injection for CO2 storage and include formations like sedimentary and igneous formations. Igneous formations like peridotite, komatiites, and basalt have huge potential to store CO2 and take the least time to convert the injected gas into solid carbonates along with the advantage of negligible leakage (as injected gas converts to carbonates through carbon mineralization). Carbon mineralization is a complex process involving the interaction of water–CO2–rock to form solid carbonates. In this review, we have highlighted the carbon mineralization in basalt by discussing the dissolution and precipitation mechanism. The discussion includes the uncertainty in the role of aluminum ions and siderite precipitation during CO2 storage in basalt. The review article also presents the first insight for the qualitative assessment of the CO2 storage potential of Deccan volcanic provinces (DVP) in India concerning the rock composition, injection depth, and type of injection. The mineralogy, and structure of the Basaltic province of DVP support CO2 storage. The principal minerals including calcic plagioclase and pyroxene, support mineral carbonation. Out of the total available area of DVP, 95% consists of tholeiitic basalt, exhibiting a simple flow structure. Additionally, the area is seismically safe for CO2 storage. The challenges and future research gap areas highlighted in this review article include suitable depth for injection, lateral continuity, the role of geothermal gradient, water availability, and public acceptance. Thus, the article provides a critical insights into the exploration and development of CCS technologies in India, emphasizing the importance of the Deccan Volcanic Provinces in achieving net-zero goals.

Assessing the groundwater quality of El Fahs aquifer (NE Tunisia) using multivariate statistical techniques and geostatistical modeling

This study is the first attempt to characterize the quality status of El Fahs aquifer by combining graphical tools, multivariate statistical techniques and traditional geostatistical methods. Water samples are collected from thirty-six observation wells during April 2016 to characterize the physicochemical properties of the aquifer. Subsequently, these samples are partitioned into three hydrochemically distinct water classes (i.e., C1, C2, and C3) using the K-means clustering method. Principal Component Analysis is used to reduce the dimensionality of the dataset prior performing the clustering computations, resulting in clusters of higher quality than the non-reduced case in terms of Silhouette coefficient. Piper diagram is used to display the chemical composition of the samples, revealing the dominant role of Mg–Ca–Cl water type for all three classes, whereas Sodium and Sulfate were found to be the second most important cations and anions respectively. Indicator kriging (IK) is used to identify the probability of occurrence of the hydrochemical classes beyond the sampling locations. It is found that Class 1, associated with fresh groundwater component, is most probable to occur at the central part of the plain, mainly due to the presence of a dense hydrological network, whereas Classes 2 (agricultural activities) and 3 (dissolution of evaporate geological formations) are expected to occur at the southern and northern regions respectively. IK also identified the regions associated with high levels of uncertainty, mostly occurring in a large portion of the northern area due to the absence of available hydrochemical information. The results showed that integration of graphical methods, multivariate statistical techniques and geostatistical modeling, is an efficient approach for characterizing the hydrochemical status of the aquifer system, to spatially optimize the groundwater monitoring well networks and quantify the uncertainty levels of the water classes in a systematic way.

Analysis on stable imaging and inverse algorithm for artificial source EM data

Abstract The inversion of artificial source electromagnetic (EM) method data fundamentally involves constructing a mathematical relationship between observable data and geological structures. The aim of imaging and inversion is to construct a geophysical model that matches the observable results, thereby realizing the identification of subsurface targets. The results of EM data inversion, due to the simplicity of geophysical models, limit inversion computing efficiency. Moreover, complexity of actual geological structures, and lack of onsite observable data, are often hindered by non-uniqueness. The challenge in the interpretation of artificial source EM data is in enhancing both the precision and expeditiousness of the inversion process. It can be classified into three main types for EM data inversion: direct imaging inversion, deterministic inversion, and stochastic inversion. To enhance computational efficiency and reduce non-uniqueness in the results, effective inversion methods, prior geological information, geophysical data, and comprehensive analysis can help mitigate the issue of non-uniqueness in EM data inversion, thereby leading to more rational geophysical interpretation results. With the progress of technology such as computing centers and the development of artificial intelligence methods, future inversion techniques will become faster, more efficient, and more intelligent, and will be applied to the interpretation of artificial source EM data.

Microbial influence in Spanish bentonite slurry microcosms: Unveiling a-year long geochemical evolution and early-stage copper corrosion related to nuclear waste repositories

The deep geological repository (DGR) concept consists of storing radioactive waste in metal canisters, surrounded by compacted bentonite, and placed deeply into a geological formation. Here, bentonite slurry microcosms with copper canisters, inoculated with bacterial consortium and amended with acetate, lactate and sulfate were set up to investigate their geochemical evolution over a year under anoxic conditions. The impact of microbial communities on the corrosion of the copper canisters in an early-stage (45 days) was also assessed. The amended bacterial consortium and electron donors/acceptor accelerated the microbial activity, while the heat-shocked process had a retarding effect. The microbial communities partially oxidize lactate to acetate, which is subsequently consumed when the lactate is depleted. Early-stage microbial communities showed that the bacterial consortium reduced microbial diversity with Pseudomonas and Stenotrophomonas dominating the community. However, sulfate-reducing bacteria such as Desulfocurvibacter, Anaerosolibacter, and Desulfosporosinus were enriched coupling oxidation of lactate/acetate with reduction of sulfates. The generated biogenic sulfides, which could mediate the conversion of copper oxides (possibly formed by trapped oxygen molecules on the bentonite or driven by the reduction of H2O) to copper sulfide (Cu2S), were identified by X-ray photoelectron spectroscopy (XPS). Overall, these findings shed light on the ideal geochemical conditions that would affect the stability of DGR barriers, emphasizing the impact of the SRB on the corrosion of the metal canisters, the gas generation, and the interaction with components of the bentonite.

Comparison of the vs30 model and site class based on MASW, microtremor and N-SPT data in the Opak River Basin

Abstract The utilization of vs30 data offers numerous applications within the geotechnical field, with one of its primary applications being the determination of site class and the microzonation of site class. vs30 data can be acquired through various methods, including Multichannel Analysis of Surface Waves (MASW), microtremor measurements, and N-SPT data. This study seeks to compare vs30 data and site class criteria based on measurements obtained from MASW, microtremor, and N-SPT data in the Opak River Basin. For the vs30 data analysis, a total of 27 data points from MASW and microtremor measurements, along with 3 data points from N-SPT measurements, were employed. These measurements were conducted across various geological formations, encompassing the young volcanic deposits of Merapi Volcano, alluvial deposits, and the Nglanggran, Sentolo, Wonosari, and Semilir Formations. It is worth noting that all N-SPT data were specifically collected within the young volcanic deposits of the Merapi Volcano Formation. The results of this analysis revealed vs30 values ranging from 159 to 192 m/s for MASW measurements, 156 to 789 m/s for microtremor measurements, and 241 to 249 m/s for N-SPT measurements. In accordance with the SNI 1726-2019 site class criteria, the site classes determined based on vs30 values from MASW and microtremor data included rock (SB), very dense soil (SC), stiff soil (SD) and soft soil (SE), while the site class based on vs30 N-SPT data fell under the stiff soil (SD) criteria. The correlation between vs30 values obtained from MASW and microtremor measurements yielded a strong correlation coefficient (r) of 0.98, and the correlation between vs30 values from MASW and N-SPT measurements demonstrated a very strong correlation coefficient (r) of 0.99.

Mechanism of Rock-Water Interaction in Kuzhithuraiyar Sub-Basin, Kanniyakumari District, Tamilnadu, India

The chemical composition of groundwater is changed by a number of hydro-geochemical processes. Rock-water interaction is the primary process that controls the ionic concentration of water, even though vaporization, concentration and dilution due to precipitation alter the chemical composition of groundwater. The chemical reactions differ depending on the preliminary composition of water, the geological formations it passes through and even how long it has been there. The 48 groundwater samples used in this study were collected, and the pH, Electrical Conductivity, Total Dissolved Solids, major cations and anions concentrations were measured. Gibb's Plot, Bivariate diagrams, Piper's Trilinear diagrams along with Saturation Indices were used to examine the mechanism of rock-water interaction in Kuzhithuraiyar Sub-Basin. Keywords: Rockwater Interaction, Bivariate Diagrams, Gibbs Plot, Pipers Trilinear Diagram, Saturation Indices