Geological Factors Research Articles

Fracture-controlled fracturing mechanism and penetration discrimination criteria for thin sand-mud interbedded reservoirs in Sulige gas field, Ordos Basin, China

Considering the problems in the discrimination of fracture penetration and the evaluation of fracturing performance in the stimulation of thin sand-mud interbedded reservoirs in the eighth member of Shihezi Formation of Permian (He-8 Member) in the Sulige gas field, a geomechanical model of thin sand-mud interbedded reservoirs considering interlayer heterogeneity was established. The experiment of hydraulic fracture penetration was performed to reveal the mechanism of initiation–extension–interaction–penetration of hydraulic fractures in the thin sand-mud interbedded reservoirs. The unconventional fracture model was used to clarify the vertical initiation and extension characteristics of fractures in thin interbedded reservoirs through numerical simulation. The fracture penetration discrimination criterion and the fracturing performance evaluation method were developed. The results show that the interlayer stress difference is the main geological factor that directly affects the fracture morphology during hydraulic fracturing. When the interlayer stress difference coefficient is less than 0.4 in the Sulige gas field, the fractures can penetrate the barrier and extend in the target sandstone layer. When the interlayer stress difference coefficient is not less than 0.4 and less than 0.45, the factures can penetrate the barrier but cannot extend in the target sandstone layers. When the interlayer stress difference coefficient is greater than 0.45, the fractures only extend in the perforated reservoir, but not penetrate the layers. Increasing the viscosity and pump rates of the fracturing fluid can compensate for the energy loss and break through the barrier limit. The injection of high viscosity (50–100 mPa·s) fracturing fluid at high pump rates (12–18 m3/min) is conducive to fracture penetration in the thin sand-mud interbedded reservoirs in the Sulige gas field.

Sensitivity analysis of geological mining influencing factors on the pressure relief effect of upper protective layer mining

AbstractTo study the influence of different geological and mining factors on the decompression effect of protective layer mining, a numerical simulation was carried out using FLAC3D numerical software. Taking the Hulusu coal mine as the engineering background, numerical simulation studies were carried out under different mining heights, working face lengths, interlayer lithologies and layer spacing by using FLAC3D numerical software, and the effects of different geological and mining factors on the degree of decompression and the scope of decompression were quantitatively investigated through the control of single‐factor variables. The results show that: the stress at the critical depth of impact ground pressure is 16.44 MPa, and the coefficient of unloading degree C = 0.5 is the indicator of sufficient unloading; the unloading effect of the protected layer decreases with the increase of layer spacing, lithological strength, and length of the working face, and increases with the increase of mining height; the geological and mining parameters of the protected layer show a functional relationship with the critical depth of the unloading, and the order of the influence of pressure relief effect is layer spacing > mining height > interlayer lithology > working face length. The results of the study are very important for the determination of the mining parameters of the protective layer, the estimation of the protective effect, and the design of the management programme of impact pressure.

THE PROSPECT OF USING GEOTECHNICAL SEISMIC INSULATION MADE OF GRUNTOSILICATE TO PROTECT ARCHITECTURAL MONUMENTS

The article explores the prospects of utilizing geotechnical seismic insulation made from gruntosilicate to protect architectural monuments from seismic influences. It highlights the advantages of this technology, including the preservation of the integrity and authenticity of historical buildings, minimal interference with their original construction, and the durability of the materials used. The article outlines the primary methods and technologies of seismic insulation, such as insulating layers, dampers, and shock-absorbing materials. Additionally, it provides examples of successful applications of seismic insulation in various historical buildings. The importance of adopting modern technologies to safeguard cultural heritage in regions with heightened seismic activity is emphasized throughout the discussion. The primary aim of the article is to demonstrate the effectiveness of geotechnical seismic insulation in preserving architectural heritage. Experimental studies have shown that gruntosilicate, when used as a seismic insulation material, significantly reduces the amplitude of seismic vibrations, thereby enhancing the safety and longevity of buildings. The article posits that geotechnical seismic insulation represents a promising approach in earthquake-resistant construction, necessitating an integrated approach that takes into account technical, economic, and geological factors. This research underscores the potential of this technology to provide sustainable solutions for the protection of cultural heritage in seismically active regions.

Prediction of Sand Production from Poorly Consolidated Formations Using Artificial Neural Network: A Case Study, Nahr Umr Formation in Subba Oil Field

Sand production in poorly consolidated formations is a significant challenge to the oil and gas industry, resulting in reduced production and compromised equipment integrity. The oil and gas industry has recently become interested in data analytics because it has significantly simplified, accelerated, and reduced the cost of data visualization. The intriguing new approaches in artificial intelligence development promise to offer long-term solutions to the increasing problems affecting the petroleum industry's operations. Any completion operation in sandstone formations is based on determining whether or not a well will produce sand. It is economically unfavorable to the Nahr Umr Formation to install sand control equipment for wells that don't produce sand. This study aims to create an efficient and precise artificial neural network that can predict sanding in sandstone formations. To achieve this, we developed a two-layered ANN with a back-propagation algorithm using JMP software. The model formulation included various geological and mechanical factors that could impact sand detachment, such as Young’s modulus (YME), Poisson’s ratio, minimum and maximum horizontal stresses (SHMIN and SHMAX), pore pressure, shale volume, and formation strength. The study acquired data from both local fields, specifically the Amarah oilfield, and non-local fields from the literature. Two sets were created from the data: a training set comprising 75% of the data, and a test set comprising 25% of the data, both of which were classified. The speed and accuracy of a learning process in an Artificial Neural Network depends on the size of the data set, the number of hidden layers, and the input parameters. The statistical measures such as accuracy, confusion matrix, root mean square error, and generalized RSquare demonstrate the strong efficacy of the created Artificial Neural Network model. The results indicate a significant likelihood of sand production occurring over the perforation intervals across Su-4 and Su-5 wells. The method's unique feature is its ability to isolate shale areas and identify weak areas capable of producing sand in sandstone formations. In conclusion, it is determined that an Artificial Neural Network employing the back-propagation algorithm is a simple, reliable, and easy-to-use method for accurately predicting sand production.

Lithophysical characteristics of productive strata of cupriferous sandstone within Zhezkazgan ore district in the Central Kazakhstan

Purpose. The paper concerns additional geological appraisal and identification of extra localization criteria of cupriferous mineralization of a stratiform type. The research is intended to define physical and geological factors influencing sandstone distribution within the north-end of Zhezkazgan synclinal in the Central Kazakhstan. Methods. A complex analysis of geological and mineralogical, geophysical, and geochemical data was carried out relying upon the information obtained from deep-hole wells. Modern methods to process and interpret the field data were applied. The analysis involved lithological dismemberment of the productive Taskuduk suite as well as determination of sulfide mine-ralization zone boundaries. Findings. The research has shown that the productive levels reach down to 1500-m depth. The data interpretation has helped specify the geological structure and develop a model of ore-promising bodies of cupriferous sandstones at great depth. The applied complex data analysis has increased potential to prospect new loci of productive cupriferous sandstone deposits of Zhezkazgan type. Originality. The research has contributed significantly to understanding of the physical and geological factors influencing the copper ore distribution in deep layers. New physical and geological criteria, determining deep copper mineralization localization, have been identified which were not considered by earlier similar studies. Practical implications. The obtained new data as well as the developed methods are important while deep drilling planning and implementing to identify promising copper mineralization sites. The findings may be used to optimize exploration within the north-end of Zhezkazgan synclinal, and other districts having analogous geological conditions.

The implications of climate change on freshwater resources in the arid and semiarid Mediterranean environments using hydrological modeling, GIS tools, and remote sensing.

Precipitation partitioning in arid and semiarid environments is not well understood due to scanty precipitation, its temporal distribution, and the lack/absence of adequate measurements of the hydrometeorological components. Simulation methods have the potential to bridge the data gap, thereby providing a window to estimate the water balance components. The present investigation evaluates the water balance components of a typical watershed situated in the southeastern Mediterranean for the period 1979 through 2019 using daily meteorological data and a grid spacing of 250 m. Generated runoff results were commensurate with corresponding values obtained using the SWAT model. Computed groundwater recharge is also compatible with recharge values calculated using the chloride mass balance method. Results show that average runoff and groundwater recharge for the entire period was ⁓24 mm a-1 and 19 mm a-1, giving a precipitation ratio of 9.5% and 7.5%, respectively. Substantial interannual variability in the water balance components was observed during the study period which reflected the significant precipitation fluctuations typifying the Eastern Mediterranean. Results show that the period extending from 1998/1999 through 2018/2019 witnessed an 18% drop in annual precipitation, while surface runoff and groundwater recharge experienced a reduction of ⁓34% and ⁓67%, respectively. Although groundwater recharge is a complex function of numerous meteorological and geological factors, the NDVI can provide an excellent indicator of groundwater recharge in marginal Mediterranean environments. This is highly beneficial in areas where climate records are scanty or absent. The presented results emphasize the significant impacts of global warming and aridification on the future availability of water resources in the semiarid marginal climates in the Eastern Mediterranean and point out clearly that water resources in this area will become scarcer, leading to multiple security threats at national and regional levels.

Numerical Simulation Study on Dynamic Interaction between Two Adjacent Wells during Hydraulic Fracturing

The heterogeneity in fracture formation significantly influences the hydraulic fracture propagation among adjacent wells, underscoring the urgency to comprehend the underlying fracture mechanisms. Specifically, in shale gas or oil extraction fracturing operations, stress interactions among neighboring fracturing clusters, or mutual interference during the propagation of parallel fractures, are commonplace. At present, there is relatively little research on the sensitivity parameters of adjacent borehole fracture propagation morphology. Consequently, we employed ABAQUS software 2022 to construct a numerical model simulating the fracturing of adjacent boreholes in opposing directions. Upon validating the model’s fidelity, we systematically explored the influence of various engineering and geological factors on fracture morphology and propagation length. Our findings revealed a three-phase evolution: independent fracture propagation, subsequent mutual repulsion, and, ultimately, mutual attraction. It is worth noting that increasing the elastic modulus from 10 GPa to 80 GPa, and increasing the crack length by 16.30%, is beneficial for crack propagation, while the horizontal stress difference profoundly shapes the crack mode, but has a relatively small impact on the overall crack length. When HSD increases from 0 MPa to 15 MPa, the total crack length only changes by 1.24%. In addition, the filtration coefficient of the reservoir is a key determining factor that has a significant impact on the morphology and length of cracks generated by adjacent boreholes. Increasing the filtration coefficient from 1 × 10−14 m3/s/Pa to 5 × 10−12 m3/s/Pa reduces the total length of cracks by 60.77%. Notably, an optimal injection rate exists, optimizing fracturing outcomes. Conversely, the viscosity of the fracturing fluid exerts a limited influence on fracture morphology and length within the confines of this simulation, allowing for the selection of a suitable viscosity to ensure smooth proppant transport during actual fracturing operations. In designing fracturing parameters, it is imperative to aim for sufficient fracture propagation length while harnessing “stress interference” to foster the development of intricate fracture networks. Ultimately, our research findings serve as a solid foundation for engineering practices involving hydraulic fracture propagation in adjacent boreholes undergoing opposing fracturing operations.

The Influence of Climatic, Geological and Hydrodynamic Factors on Slope Stability at Kekem in the West Region of Cameroon

This study focuses on the influence of climatic, geological and hydrodynamic factors on slope stability of Kekem located in the Western Highlands of Cameroon. The methodological approach was based on the analysis of three factors: hydrological, geological and assessment of the hydrodynamic parameters influencing the stability of slopes. The hydrological factors indicate an average annual rainfall of 1,763.04 mm, generating 248.59 mm of runoff and around 402.61 mm of infiltrated water. Geologically, the soils have a high angle of friction at all three elevations, from 25.8° at the bottom of the slope to 27.2° at mid-slope and 26.2° at the top. On the other hand, the cohesion of these soils remains low, varying from 0.325 bar at the bottom of the slope to 0.265 bar at the top and 0.225 bar at mid-slope. Permeability analysis yielded values ranging from 1 x 10-9 to 1 x 10-11 m/s, with an overall porosity of around 55%. These conditions, combined with the morphology of the environment, are the main causes of slope instability in the Kekem district.

Susceptibility assessment of glacier-related debris flow on the southeastern Tibetan Plateau using different hybrid machine learning models

The southeastern Tibetan Plateau (SETP) is a construction area of several key infrastructure projects in China, such as the Sichuan-Tibet Railway and hydropower developments, which has historically faced the threat of glacier-related debris flows. However, a robust assessment of such debris flow susceptibility is a challenge due to the complex and variable climate, terrain and glacial environment. In this study, we used the hybrid models that combine statistical techniques (certainty factors, CF) with machine learning methods (logistic regression, LR; random forest, RF; extreme gradient boosting, XGBoost) to more accurately identify debris flow susceptible (DFS) areas. Topography, geology, and hydrological factors including glaciers and snow cover were used in these models to assess the DFS. Results show that 21 % to 42 % of the study area is very high susceptible to debris flows, particularly from Ranwu to Bomi and around Namcha Barwa. The hybrid models effectively enhance the accuracy of the DFS assessments. The CF-RF model showed the greatest improvement, with an 8.4 % increase in accuracy compared to the single model, the DFS spatial distribution of which aligns closely with field survey results. The glacial area ratio and annual snowmelt positively impact DFS accuracy, ranking 2nd and 9th in the factor importance, respectively. The results of this research could provide valuable assistance and guidance in mitigating glacier-related debris flow hazards.

Geological factors in the sustainable management of mine water heating, cooling and thermal storage resources in the UK

Re-use of the UK's coal mine water heating, cooling and thermal storage resource is increasing in scale and the number of schemes. The upward trajectory requires 3D planning, regulation and licensing to manage sustainable deployment. We review geological factors controlling thermal and flow processes in the anthropogenically-altered subsurface, critical for resource management with multiple users of the same space. Potential interactions of mine water geothermal schemes with the wider environment are also summarized, leading towards concepts of 3D mine water thermal blocks, protection zones, or management strategies integrating heating, cooling and storage demands. Factors such as the magnitude, extent and timescale of thermal processes to underpin management approaches are poorly quantified by data measured at-scale under varying pumping rates and thermal loads. We demonstrate early insights of how two infrastructures, the UK Geoenergy Observatory in Glasgow and the Coal Authority's Mine Water Heat Living Lab in Gateshead, can measure and monitor heat-flow processes in real world settings to provide an evidence base. For example, a thermal storage test at Glasgow showed rapid temperature changes in the rock and mine workings at the re-injection borehole and indicated an influence of lithologically-controlled transmissivity and thermal conductivity on temperature dissipation and recovery.

Insights on Prioritization Methods for Mining Exploration Areas: A Case Study of the Tiltil Mining District, Chile

This study proposes a simple and replicable methodology to prioritize mining exploration projects based on their geoscientific characteristics and contextual factors, which can be adapted to different mining contexts. Using the Tiltil Mining District in Central Chile as a case study, where over 100 small and medium-sized Au and Cu prospects exist, this research outlines three key stages: (1) collection of relevant data; (2) selection of the most appropriate multi-criteria decision-making methods (MCDMs); and (3) the application, analysis, and comparison of these methods. This study identifies AHP and PROMETHEE II as the most suitable MCDM for the case study. The application of these methods consistently ranked El Huracán, San Aurelio, and La Despreciada as the top three exploration priorities. The AHP’s weight assignment highlights economic, geological, and social factors as the most critical variables in determining project viability.

Effects of organic richness, mineral composition, diagenesis, and thermal maturity on the viscoelastic properties of organic-rich Cretaceous mudstones in the Middle Magdalena Valley basin, Colombia

A major geological risk factor for engineering and energy-related applications, such as CO2 storage and unconventional hydrocarbon production, is the geomechanical integrity of mudrocks. The goal of this work is to better constrain the macroscopic mechanical properties resulting from microstructural components by investigating the effects of thermal maturity, mineral composition, diagenesis and organic richness on the mechanical properties of Cretaceous mudstones in two surface sections (San Vicente de Chucurí and La Cristalina Creek) and one well (La Luna-1) from the Middle Magdalena Valley Basin (MMVB), Colombia. The thermal maturity of 22 rock samples was evaluated via organic source-rock screening and determination of illite crystallinity (Reichweite). Both geothermometers placed the La Luna Formation rock samples from San Vicente de Chucurí and the La Luna-1 well within the oil generation window (80°C–120 °C). In contrast, the rock samples of the Guaguaquí Group from La Cristalina Creek in the southern part of the basin are within the gas window (>180 °C). The mineralogy of organic-rich mudstones in the MMVB is dominated by quartz and calcite. Moreover, mudstones from the MMVB have a wide range of organic richness and clay contents, with organic abundances comparable to and clay contents lower than those found in other source-rock reservoirs. The Young's modulus (EIT), Martens hardness (HM), and creep (CIT), as determined through microindentation experiments, highly varied, but overall, the findings suggest that the Cretaceous rocks of the MMVB present conditions favorable for hydraulic fracturing. Furthermore, the viscoelastic properties of Cretaceous rocks in the MMVB are influenced primarily by the concentrations of strong minerals (quartz and calcite) and weak components (clay and TOC). Specifically, an increase in the concentration of weak components compared with that of strong minerals leads to an increase in CIT and a decrease in HM and EIT, and vice versa. Unlike other source-rock reservoirs, there are no indications of a strong correlation between thermal maturity and mechanical properties, suggesting a decoupling of these parameters in rocks of the MMVB. A close scanning electron microscopy examination of the rocks indicated that the observed weak to moderate correlation between thermal maturity and mechanical properties appears to result from rock silicification and calcite cementation caused by the precipitation of these minerals at early stages of diagenesis. This observation implies that the impact of diagenesis on rock geomechanics of silica-rich and calcareous-rich mudstones may override or be more important than the effects of thermal maturity, which, along with clay and organic matter contents, are the greatest controls in the geomechanics of argillaceous source-rock reservoirs.

A framework for territorial spatial ecological restoration zoning integrating “Carbon neutrality” and “Human-geology-ecology”: Theory and application

Global climate change worsens the imbalance among human environment, geological environment and ecological environment (human-geology-ecology), leading to increasingly prominent ecosystem damage. Constructing a scientifically effective territorial spatial ecological restoration zoning (TSERZ) framework will promote the coordination between nature and human. However, the fundamental role of geological environment in TSERZ has been overlooked, and there is lack of theoretical frameworks and empirical research on TSERZ oriented towards carbon neutrality goal. Therefore, we have proposed a new TSERZ framework by integrating “carbon neutrality” and “human-geology-ecology”, which employs models such as CECM, LCA, IUEMS and ESP to divide primary zones, secondary zones and key areas, and also provides restoration directions for various zones. Taking the typical alpine-gorge region of Yulong County as an example, we conduct empirical research to verify the validity of the TSERZ framework. The findings indicate that, firstly, besides human and ecological factors, geological factors like lithology are indispensable factors for TSERZ, and understanding the dynamic balance relationship of human-geology-ecology is the prerequisite and basis for TSERZ. Secondly, the proposed TSERZ framework emphasizes the fundamental role of carbon source/sink and lithology in TSERZ, constructing the three-level zones division method oriented towards carbon neutrality goal with the research line of “natural background conditions—dominant ecological functions—ecological stress problems”. Thirdly, the framework has been successfully applied to TSERZ in Yulong County, dividing it into 8 primary zones, 17 secondary zones, and 7 types key areas. Given its complex geological conditions, fragile ecological environment and increasingly human interference, Yulong County urgently needs to focus on restoring ecological problems such as rocky desertification and geological disasters to improve carbon sink capacity. This study innovatively constructs a cascading path for TSERZ from theoretical cognition to practical application, which can provide a reference for solving the TSERZ problem in geologically complex regions, especially in alpine-gorge regions.

Multitemporal analysis of cliffs evolution along an Atlantic African coast (Safi Region, Morocco)

Unstable coastal cliffs represent a major threat to coastal infrastructure, housing, and economic activities, which depend on coastal stability. Understanding recession rates and the factors influencing them is therefore essential for enhancing risk prediction and management. Here, we investigated the evolution of coastal cliffs in a crucial sector of the Atlantic African coast in Morocco, stretching from Cap Beddouza in the north to Jorf Lihoudi in the south, covering an area of around 48 km and including the large city of Safi. The instability of these cliffs constitutes the main coastal geological hazard of the area, which has its geomorphological expression in different types of landslides punctuating the coastal cliff. We employed multidecadal aerial imagery along with GIS technique to calculate the rate of change of the cliff over 66 years. Our results indicate that most of the Safi Region coastal zone has undergone recession with rates of change generally variable from 0.04 to 0.08 m/yr ± 0.01 m. The central part of the study area, conversely, experienced the highest retreat rate, exceeding 0.10 m/yr. The spatial variability of recession rates is explained through geological and morphological factors such as the nature of low-strength clay rock formations, favoring large-scale gravity movements. These data are crucial to better define the current level of coastal hazard in this densely populated portion of the Moroccan coast, given that cliff recession have considerable effects on the economic, social and environmental risk of the area. Moreover, this study represents one of the first applications of the Digital Shoreline Analysis System (DSAS) method to an African coastline segment, specifically from Cape Beddouza to the Lihoudi cliffs. More generally, it is among the few studies focused on cliff recession rates in Africa. While a similar application has been conducted for the cliff base in the northern part of the same study area (Raja et al., 2023), that study primarily addresses coastal cliff failure hazards along the Safi coastline in Morocco. In contrast, the present study is focused on determining long-term cliff recession rates and understanding the distribution of these rates and modes of retreat in relation to the physical processes affecting the study area.

Numerical simulation study of fracture propagation by internal plugging hydraulic fracturing

Internal temporary plugging fracturing technology improves the stimulated volume by forming a more complex fracture network, significantly enhancing the reservoir stimulation effect and effectively developing unconventional oil and gas resources. However, the current understanding of the fracture propagation mechanism on internal temporary plugging fracturing is still unclear, making it difficult to determine the main controlling factors that affect the shape of the fractures. In addition, the lack of practical numerical simulation methods for temporary plugging fracturing makes it challenging to provide guidance for field scheme design. Utilizing the finite element cohesive zone method, which incorporates globally embedded cohesive elements, this study constructs a comprehensive numerical model to investigate the propagation behavior of temporarily plugging fracturing fractures. The model delves into the impact of various geological and construction parameters on the opening conditions of branch fractures during the temporary plugging fracturing process, as well as the propagation patterns of fractures within naturally fractured reservoirs. The research findings indicate that the construction factors have the following impacts: When the pumping rate and viscosity of the fracturing fluid are comparatively high, the resulting fluid pressure within the fracture escalates, resulting in the creation of numerous branch fractures within the naturally fractured reservoir. This, in turn, augments the fracture’s complexity. However, these two factors have little influence on the maximum deflection distance of the deflected fracture. As for the geological factors, an increase in the horizontal stress difference will decrease the maximum deflection distance of the deflected fracture, reducing the number of natural fractures intersected and shortening the length of the deflected fracture. Conversely, an increase in the approach angle will increase the maximum deflection distance of the deflected fracture, thereby expanding the affected area. Additionally, the influence of Young’s modulus and Poisson’s ratio on fracture propagation is very slight. A decrease in the tensile strength of natural fractures leads to more natural fractures being intersected during the process, resulting in increasing the length of the fracture and an improvement in the complexity of the fracture grid.

Landscape patterns of carbon fluxes in natural and disturbed ice-wedge-polygon tundra

ABSTRACT The degradation of ice-rich permafrost ecosystems due to climate change and infrastructure development strongly impacts carbon exchange dynamics in tundra landscapes. This study investigates the effects of surficial geology and infrastructure disturbances from road dust and flooding on vegetation and trace gas fluxes in polygonal ice-wedge tundra in arctic Alaska. We compared CO2 and CH4 fluxes from closed-chamber measurements at common landform elements (polygon centers, troughs, and rims) at a natural site and a disturbed site within the Prudhoe Bay Oil Field. Relationships among environmental parameters, plant species composition, and trace gas fluxes were assessed through nonmetric multidimensional scaling. Map extrapolations showed spatial variations in midsummer landscape-level ecosystem productivity and CH4 efflux at the various geologic landforms. Highest carbon uptake occurred in ice-rich drained thaw lake basins with aquatic, graminoid-dominated polygon troughs. In contrast, wet, featureless areas associated with more recently drained, ice-poor thaw lake basins showed a net carbon loss even during summer. The damming effect of road infrastructure led to deeply flooded, minimally vegetated troughs with low ecosystem respiration and high CH4 fluxes close to the road. This work highlights the importance of the complex interactions among surficial geology, landform elements, vegetation type, and disturbance factors in understanding carbon exchange dynamics in ice-rich permafrost environments.

Concentrations of F−, Na+, and K+ in Groundwater before and after an Earthquake: A Case Study on Tenerife Island, Spain

Freshwater, vital for life and ecosystems, accounts for only 2.5% of Earth’s water, and is primarily located in polar caps, underground reservoirs, and surface water. Its quality varies due to environmental interactions, especially in groundwater. Tenerife, located in the Canary Islands, Spain, relies mainly on underground aquifers and tunnels capturing 51.6 cubic hectometers annually. Ensuring safe drinking water is a global challenge due to health risks from poor water quality, including diseases and cancer. Fluoride, sodium, and potassium are essential for health, and are mainly derived from groundwater as fluoride ions (F−) and sodium and potassium cations (Na+, K+). However, excessive F−, Na+, and K+ in drinking water is harmful. The World Health Organization limits F− to 1.5 mg/L, Na+ to 8.70 meq/L, and K+ to 0.31 meq/L. Geological, climatic, and human factors control the presence and transport of F−, Na+, and K+ in groundwater. Seismic events can impact water quality, with long-term effects linked to aquifer structure and transient effects from gas and fluid expansion during earthquakes. This study was motivated by a 3.8 mbLg earthquake in Tenerife in 2012, which allowed its impact on groundwater quality, specifically F−, Na+, and K− concentrations, to be examined. Post-earthquake, F− levels alarmingly increased to 8.367 meq/L, while Na+ and K+ showed no significant changes. This research quantifies the influence of earthquakes on increasing F− levels and evaluates F− reduction during low seismic activity, emphasizing the importance of water management on volcanic islands.

Permafrost thaw and thermokarst in the source region of the Yangtze river in the central Tibetan plateau revealed by radar and optical remote sensing

AbstractThe landscape and landforms in permafrost regions are transforming due to climate change and permafrost thaw. This study uses optical and radar remote sensing, alongside spatial analysis, to examine thermokarst features and their driving factors in the source region of the Yangtze River (SRYR) on the central Tibetan Plateau. We analyse the distribution, interaction, and key environmental factors influencing thermokarst ponds and ground surface deformation, which are the two widespread and noticeable thermokarst features. Since the 1960s, the number of small water bodies has doubled from approximately ~2 × 104 to ~4 × 104 by the 2020s, with the median size of these water bodies decreasing from 2.3 × 104 m2 to 1.4 × 104 m2. The permafrost terrain has an average subsidence rate of 6.8 mm/a. About 50.9% of the SRYR exhibits evident thermokarst features. Surficial geological factors, especially geomorphology and slope, are primary factors in shaping the spatial distributions of thermokarst features. Both seasonal deformation and long‐term subsidence rates are more pronounced in areas with thermokarst ponds. However, once pond coverage exceeds around 5%, the amplifying effect on long‐term subsidence rates and seasonal deformation diminishes. The investigation further reveals that the relationship between seasonal deformation and long‐term subsidence is not strictly linear and that the combined increase in seasonal deformation and long‐term subsidence applies only to areas with seasonal deformation below approximately 20 mm. Beyond this threshold, the long‐term subsidence rate is no longer exacerbated by increased seasonal deformation.

Effect of bedrock, tree size and time on growth and climate sensitivity of Norway spruce in the High Tatras

AbstractTree growth is a multifaceted process influenced by various factors at different spatial and temporal scales, including intrinsic tree traits and environmental conditions. Climate factors have a significant impact on tree growth dynamics, while geological controls can also play a crucial role. However, our understanding of the interplay between these factors concerning tree growth is currently limited. This study focuses on Norway spruce (Picea abies [L.] Karst.), one of the economically most important coniferous tree species in Europe, to investigate the interplay of growth, climate, and environment at the forest and corresponding treeline sites in the High Tatra Mountains of Slovakia. Specifically, we developed chronologies of tree-ring width (TRW) and late-wood density (MXD) for different tree size classes across two limestone and granitic sites. Growth rates of Norway spruce trees have been increasing in forests since the 1930s and from the 1950s at treelines. Growth rates were consistently higher on limestone bedrock compared to granitic bedrock conditions. Variability of radial growth is primarily driven by climate at both geological settings with trees on granitic bedrock displaying more pronounced responses to climatic variables. We observed weakening (non-stationarity) in climate signals over time and across all size classes in both geological settings. The magnitude of these effects is small, but varies across size classes, with larger trees generally displaying stronger climate sensitivities compared to smaller ones. Therefore, our findings accentuate the potential implications of geological settings, climate, and environmental factors on the absolute growth and growth dynamics of Norway spruce, highlighting the need for further research to fully understand and manage forest ecosystems in mountainous regions.

Ecological Status Assessment of Permafrost-Affected Soils in the Nadym Region, Yamalo-Nenets Autonomous District, Russian Arctic

Permafrost-affected regions in the Russian Arctic are a critical study area for studying the sources of metal elements (MEs) in soils originating from geological/pedogenic processes or from anthropogenic sources via atmospheric transport. In the Nadym region of the Yamalo-Nenets Autonomous District, we investigated the contents of soil organic carbon (SOC), total nitrogen (TN), and MEs across different soil types and horizons, explored the source apportionment of MEs, and assessed local ecological risks of potentially toxic elements (PTEs). The results showed that (1) the contents of SOC and TN in Histic Cryosols (8.59% and 0.27%) were significantly higher than in Plaggic Podzols (Arenic, Gelic, and Turbic) (2.28% and 0.15%) and in Ekranic Technosols (Umbric) (1.32% and 0.09%); (2) the concentrations of MEs in the Nadym region were lower than in other Arctic regions; (3) the primary sources of MEs were identified as geological processes (36%), atmospheric transport (23%), agricultural activities (21%), and transportation (20%); and (4) the permafrost-affected soils in the Nadym region exhibited low ecological risks from PTEs. These results underscore the critical role of geological and anthropogenic factors in shaping soil conditions and highlight the relatively low ecological risk from PTEs, providing a valuable benchmark for future environmental assessments and policy development in Yamal permafrost regions.