Developmental Features, Influencing Factors, and Formation Mechanism of Underground Mining-Induced Ground Fissure Disasters in China: A Review

Mining-induced ground fissures are one of the major geological disasters affecting coal mines. In recent years, many effective monitoring methods have been developed to explore the developmental characteristics and nature of mining-induced ground fissures for being treated scientifically. This paper is mainly on the development law and mechanism of mining ground fissure research results which have been comprehensively combed, highlighting the development trend, including the formation condition, development features, influencing factors, and mechanical mechanism of mining-induced ground fissures. Outstanding issues are discussed and future research hot spots and trends are pointed out. The major conclusions include: (1) under the shallow coal mining condition, because the rock layer fault zone directly reaches the surface, the ground fissure usually develops seriously; (2) mining-induced ground fissures are generally divided into four types: tensile fissures, compression fissures, collapsed fissures, and sliding fissures; (3) mining-induced ground fissures are affected by the coupling effect of underground mining and surface topography. The main factors are geological mining conditions, surface deformation, and surface topography, including rock and soil structure, rock and soil mechanical properties, surface horizontal deformation, surface slope, and so on; and (4) to ensure the safety of underground mining, temporary ground fissures formed during the process of coal mining must be treated when ground fissures and rock ground fissures are connected. The results of this article make up for the deficiencies of the relevant research, provide the basis and direction for future research, and have universal applicability and scientific guiding significance.

Impact of injection temperature and formation slope on CO2 storage capacity and form in the Ordos Basin, China

Carbon dioxide (CO2) storage capacity is the main criterion for assessing CO2 geological storage. Based on actual data from the Shiqianfeng formation in the Ordos Basin, three-dimensional (3D) models were built using the TOUGHVISUAL visualization software and simulated using the TOUGH2 integral finite difference modeling code with the ECO2N fluid property module to explore the impact of formation attributes (formation slope) and controllable factors (injection temperature) on CO2 storage capacity. A total of 16 schemes were designed, with four injection temperatures (24 ℃, 31 ℃, 38 ℃, and 45 ℃) and four formation slopes (0°, 5°, 10°, and 15°). Simulation results showed that the injection temperature and formation slope both had a significant influence on CO2 storage capacity. The impact of injection temperature on the total storage amount was more obvious than that of the impact of formation slope. A higher injection temperature resulted in a greater total storage amount. Increasing the formation slope and injection temperature increased the gas-phase, dissolved-phase, and total CO2 storage amounts in the upper left section of the injection well, but decreased them in the lower right part of the injection well. The impact of formation slope on the conversion rate from gas-phase CO2 to dissolved-phase CO2 was more obvious than the impact of injection temperature. A steeper formation slope resulted in a higher conversion rate. A smaller formation slope and a higher injection temperature should be selected to store CO2.

Reef islands have continually adjusted to environmental change over the past two millennia

Global environmental change is identified as a driver of physical transformation of coral reef islands over the past half-century, and next 100 years, posing major adaptation challenges to island nations. Here we resolve whether these recent documented changes in islands are unprecedented compared with the pre-industrial era. We utilise radiometric dating, geological, and remote sensing techniques to document the dynamics of a Maldivian reef island at millennial to decadal timescales. Results show the magnitude of island change over the past half-century (±40 m movement) is not unprecedented compared with paleo-dynamic evidence that reveals large-scale changes in island dimension, shape, beach levels, as well as positional changes of ±200 m since island formation ~1,500 years ago. Results highlight the value of a multi-temporal methodological approach to gain a deeper understanding of the dynamic trajectories of reef islands, to support development of adaptation strategies at timeframes relevant to human security.

Application of residuals from purification of bivalve molluscs in Galician to facilitate marine ecosystem resiliency through artificial reefs with shells - One generation

The seas and oceans of the planet provide a wide range of essential resources. However, marine ecosystems are undergoing severe degradation due to the unsustainable exploitation and consumption patterns of the linear economy. On the other hand, many economic activities linked to the sea generate a large amount of waste, leading to negative impacts, such as the cost of treating or disposing of this waste. A case in point is bivalve mollusc production: a purification process is needed to avoid the risk of diseases through faecal contamination. The present work proposes an innovative procedure to convert this waste, calcium carbonate as calcite and aragonite allotropic types, into by-products. These by-products can be used to manufacture green artificial reefs, partially replacing concrete aggregates with a sustainable alternative to the geological sources of CaCO₃. By installing these reefs, marine ecosystems could be created in a sustainable way and an innovative approach based on the circular economy could be taken towards protecting them. To this end, different concrete mixtures with bivalve shells are proposed. Although this study had been carried out for Galicia (NW Spain), the methodology followed could also be valid for other regions. A physicochemical characterisation of the waste from purifying the bivalves, including oysters, mussels, clams and scallops, was performed. Statistical and multi-criteria analyses were done in order to select the best dosage. Both have provided justification for using a mixture of shells with a predominance of calcite (oyster, scallop) instead of shells with a predominance of aragonite. The multi-criteria analysis served to identify the two best alternatives with dosages in which the medium aggregates were substituted with shells mainly from oysters, with a predominance of calcite. Finally, the statistical analysis played a role in estimating the compressive strength and water absorption of each mixture from the design parameter values.

Influence of Coal Mining on Historical Buildings: Case Study in Shanxi

Numerous historical buildings exist in Shanxi Province, a major coal producing area in China, so there exist many overlapping areas between ancient wooden buildings and coal mining. Coal mining in overlapping areas will lead to surface subsidence, which will have an impact on historical buildings. Based on the distribution of historical buildings and the distribution and mining of coal resources in Shanxi Province, this paper concludes that the overlapping areas of coal mining and ancient wooden buildings in Shanxi Province are mainly concentrated in Changzhi City, and the Lu'an mining area in Changzhi City is selected as the research object. In addition, using the gray correlation analysis method, the surface subsidence coefficient, which characterizes the intensity of mining subsidence, is used as the reference sequence. Seven factors selected from the geological conditions and mining conditions of the Lu'an mining area are used as the comparison sequence to calculate the gray correlation between each influencing factor and the surface subsidence coefficient, and to obtain that geological factors such as the nature of the overlying rock layer, bedrock thickness and dip angle of the coal seam, and mining factors such as mining height, average mining depth and working face size largely determine the surface subsidence coefficient. The surface subsidence in the overlap area could largely be influenced by geological factors such as the nature of the overlying rock layer, bedrock thickness and coal seam inclination, and mining factors such as mining height, average mining depth and working face size. Finally, we investigate the possible effects of surface subsidence on ancient wooden buildings in the overlapping area with the surface subsidence and formation mechanism and propose technical measures to reduce the effects of surface subsidence due to coal mining on historical buildings in the overlapping area.

Assessment of environmental geological disaster susceptibility under a multimodel comparison to aid in the sustainable development of the regional economy

Environmental geological disasters pose a significant threat to human life, property and environmental safety. It is necessary to conduct targeted governance in key prevention and control areas based on reasonable susceptibility assessment. Using the debris flow disaster in Xiuyan County as an example, this study compares and analyzes prone prediction models such as the frequency ratio (FR), decision tree (DT) and random forest (FR) models and evaluates the cost of prevention and control and the protection of life and property. The research results show that the FR, DT and RF models have good performance. The ROC test, disaster point density statistics and cross-validation results show that the RF model has the best performance. The study area was mainly less and mildly prone areas. The highly prone areas are mainly distributed in the northeast and southwest of the study area. It is the key area of disaster prevention and control. Elevation, rainfall intensity and population density have the largest influence on the susceptibility to debris flows. Based on the RF model, the disaster points in the highly prone areas account for 54% of the disaster points of the whole area, and the project treatment cost of the disaster points is 0.78 million yuan per single gully, which protects 56% of the lives and property in the study area, which is better than the DT and FR models. The RF model not only has good prediction performance in terms of susceptibility. It can realize the targeted management of disasters, achieve the targeted investment of governance costs and the effective protection of life and property and serve the sustainable development of the regional environment and economy with greater value.

Quality and hydrochemical assessment of groundwater in geological transition zones: a case study from N.E. Nigeria

Sustainable management of groundwater resources in geological transition zones (GTZ) is essential due to their complex geology, increasing population, industrialization, and climate change. Groundwater quality monitoring and assessment represent a viable panacea to this problem. Therefore, there is a great need to investigate groundwater resources in terms of their chemistry and pollution to ascertain their quality and implement robust pollution abatement strategies. This study focused on the characterization of groundwater in a typical geological transition zone in northeastern Nigeria. Eighty-seven (87) groundwater samples were collected from dug wells and boreholes during the 2017 dry season. pH, conductivity, and total dissolved solids (TDS) were measured in situ using a multiparameter probe, while major cations and anions were measured using atomic absorption spectrometry and ion chromatography, respectively. Data were analyzed using descriptive statistics, principal component analysis (PCA), water quality index, and standard hydrochemical plots. TDS ranged between 95 and 1154 mg L^-1 in basement terrains and between 49 and 1105 in sedimentary areas. pH ranged between 6.8 and 7.7 mg L^-1 in basement terrains and between 5.0 and 6.5 in sedimentary areas, suggesting a moderately acidic to alkaline low mineralized groundwater. Calcium (2.6-128.0 mg L^-1) was the dominant cation in the basement areas, suggesting silicate weathering/dissolution, while sodium (1.9-106.0 mg L^-1) dominated the sedimentary zones due to base exchange reactions. The PCA analysis suggests that mineral dissolution (mostly silicate weathering) controls the hydrochemistry of the basement aquifers, while ion exchange and albite weathering, with some influence of anthropogenic factor, control the sedimentary aquifers. The water quality index revealed that the basement setting was predominated by poor to unsuitable groundwater, while the sedimentary terrain was characterized by potable groundwater. The dominant hydrochemical facie in the basement areas was Ca²⁺-(Mg²⁺)-HCO₃^- characteristic of recharge meteoric water. The Na⁺- (K⁺)-HCO₃^- facie characterized the sedimentary zones, indicative of cation exchange reactions, while the mixed water facie typifies the geological contact zones. The shallow nature of the basement groundwaters makes them more susceptible to geogenic and anthropogenic pollution compared to the sandstone aquifers. However, the basement aquifers have better irrigation indices (Kelly ratio and soluble sodium percent) as compared to the sandstone aquifers, which exhibit poor Kelly ratios (< 1) and soluble sodium percent (> 50) ratings. Results from the study clearly highlight the poor-unsuitable groundwater quality in parts of the studied GTZ and can be very instrumental to the policymakers in implementing sustainable water treatment strategies and cleaner production technologies in GTZ to forestall the incidence of water-related diseases.

A Cost-Effective Distributed Acoustic Sensor for Engineering Geology

A simple and cost-effective architecture of a distributed acoustic sensor (DAS) or a phase-OTDR for engineering geology is proposed. The architecture is based on the dual-pulse acquisition principle, where the dual probing pulse is formed via an unbalanced Michelson interferometer (MI). The necessary phase shifts between the sub-pulses of the dual-pulse are introduced using a 3 × 3 coupler built into the MI. Laser pulses are generated by direct modulation of the injection current, which obtains optical pulses with a duration of 7 ns. The use of an unbalanced MI for the formation of a dual-pulse reduces the requirements for the coherence of the laser source, as the introduced delay between sub-pulses is compensated in the fiber under test (FUT). Therefore, a laser with a relatively broad spectral linewidth of about 1 GHz can be used. To overcome the fading problem, as well as to ensure the linearity of the DAS response, the averaging of over 16 optical frequencies is used. The performance of the DAS was tested by recording a strong vibration impact on a horizontally buried cable and by the recording of seismic waves in a borehole in the seabed.

Alexander Dalrymple, the Utility of Coral Reefs, and Charles Darwin's Structure and Distribution of Coral Reefs

This paper aims to establish the connection between the theoretical and practical aims of the Office of the Hydrographer of the British Admiralty and Charles Darwin's (1809-1882) work on coral reefs from 1835 to 1842. I also emphasize the consistent zoological as well as geological reasoning contained in these texts. The Office's influences have been previously overlooked, despite the Admiralty's interest in using coral reefs as natural instruments. I elaborate on this by introducing the work of Alexander Dalrymple (1737-1808), the first hydrographer of the Admiralty and a figure who has flown under the radar of the history of coral reef theories. I show that Dalrymple introduced a unified account of coral reefs in which multiple features of the coral reefs, such as their shape, slope of the sides, ridges, channels, and elevation relative to the water, were all explained by the action of the winds and waves-and proposed that one could use these features to predict seafaring conditions around the islands. Then, I show that Darwin's "Coral Islands" (1835) and his Coral Reefs monograph (1842) spoke to these hydrographical issues and did so, at times, by way of zoological reasoning. It was, for instance, the coral behavior and the related notion of a zoological or botanical station that ultimately proved the biggest blow to the Admiralty's aim to use the coral reefs as instruments because it eroded many uniform predictions regarding the past or future of a coral reef. Connecting these themes leads us to a surprising conclusion: that Darwin's theory of coral reefs, long a model instance of Darwin making uniform predictable inferences, was, in actuality, also his first formal encounter with something at times the entire opposite.

Influence of local geological data and geographical parameters to assess regional health impact in LCA. Tomsk oblast', Russian Federation application case

The research paper is aimed to modify the human health impact assessment of Cr in soils. The current article presents the input of several critical parameters for the human health Impact Score (IS_hum) assessment in soils. The modification of the IS_hum is derived using geological data - results of neutron activation analysis of soils are used in the IS_hum calculation; research area is divided using the watersheds and population size and density. Watersheds reflect the local environmental conditions of the territory unlike the administrative units (geographical areas of the studied region) due to their geological independence. The calculations of the characterization factor value underestimate the influence of the population size and density on the final result. Default characterization factor values cannot be considered during the assessment of the potential human health impact for the big sparsely inhabited areas. In case of very low population density, the result will be overrated and underestimated in the opposite case. The current approach demonstrates that the geographical separation in the USEtox model should be specified. The same approach can be utilized for other geo zones due to the accessibility of this information (area size, population size, and density, geological, and landscape features).

Property of mud and its application in cosmetic and medical fields: a review

Mud is a semi-colloidal substance formed by the mixture of inorganic, organic and water under the influence of various physical and chemical factors through geological and biological processes. The chemical composition of mud is complex, rich in Ca²⁺, Zn²⁺, Mg²⁺, Na⁺ and other mineral elements, also contains organic matter such as humic acid, fulvic acid and acetic acid. In cosmetic field, mud can improve the activity of glutathione enzyme and superoxide dismutase in skin, which helps the skin anti-aging. Besides, it also can improve the skin microbial community, due to its distinctively physical properties, mineral ions, microorganisms, etc. In medical field, mud can treat osteoarthritis, especially knee osteoarthritis which has been studied extensively, and it can also increase the chemotaxis of macrophages. On the one hand, the use of clay (a kind of refined mud) can protect the gastrointestinal tract and treat some gastrointestinal diseases. On the other hand, clay is often used as carriers or composites in drug delivery, especially in skin drug delivery, showing very positive results. The purpose of this review is to present an overview of current knowledge about the application of mud in cosmetic and medical fields and to provide ideas for further research in mud.

Identifying sensitivity of factor cluster based gully erosion susceptibility models

The present study has attempted to address the issue of sensitivity of different clusters of factors towards gully erosion in the Mayurakshi river basin. Firstly, the gully erosion susceptibility of the basin area has been mapped by integrating using 18 parameters divided into four factor-cluster, viz. erodibility, erosivity, resistance, and topographical cluster, with the help of four machine learning (ML) models such as random forest (RF), gradient boost (GBM), extreme gradient boost (XGB), and support vector machine (SVM). Results show that almost 20% and 25% of the upper catchment of the basin belongs to extreme and high gully erosion susceptibility. Among the applied algorithms, RF is appeared as the best performing model. The spatial association of factor cluster-based models with the final susceptibility model is found the highest for the erosivity cluster, followed by the erodibility cluster. From the sensitivity analysis, it becomes clear that geology and soil texture are dominant contributing factors to gully erosion susceptibility. The geological formation of unclassified granite gneiss and geomorphological formation of denudational origin pediment-pediplain complex is dominant over the entire upper catchment of the basin, and therefore, can be considered regional factors of importance. Since the study has figured out the different grades of susceptible areas with dominant factors and factor cluster, it would be useful for devising planning for gully erosion check measures. From economic particularly food security purpose, it is very essential since it is concerned with precious soil loss and negative effects on agriculture.

Application of Combined Local and Global Optimization Algorithms in Joint Interpretation of Direct Current Resistivity and Seismic Refraction Data: A Case Study of Dammam Dome, Eastern Saudi Arabia

The main geological structures in the Dammam Dome are defined by integrating geophysical measurements and applying new methodological approaches. Dammam Dome is characterized by a well-developed fracture/joints system; thus, high complexity of the subsurface is expected. Direct Current Resistivity (DCR) and Seismic Refraction (SR) geophysical survey aimed to map the Dammam Dome's near-surface features. The geophysical data were acquired along two profiles in the northern part of Dammam Dome. To maximize the results from conducting DCR and SR measurements over a complex area, a combined local and global optimization algorithm was used to obtain high-resolution near-surface images in resistivity and velocity models. The local optimization technique involves individual and joint inversion of the DCR and SR data incorporating appropriate regularization parameters, while the global optimization uses single and multi-objective genetic algorithms in model parameter estimation. The combined algorithm uses the output from the local optimization method to define a search space for the global optimization algorithm. The results show that the local optimization produces satisfactory inverted models, and that the global optimization algorithm improves the local optimization results. The joint inversion and processing of the acquired data identified two major faults and a deformed zone with an almost N-S direction that corresponds with an outcrop were mapped in profile one, while profile two shows similar anomalies in both the resistivity and velocity models with the main E-W direction. This study not only demonstrates the capability of using the combined local and global optimization multi-objectives techniques to estimate model parameters of large datasets (i.e., 2D DCR and SR data), but also provides high-resolution subsurface images that can be used to study structural features of the Dammam Dome.

Real-time joint ocean acoustics and circulation modeling in the 2021 New England Shelf Break Acoustics experiment (L)

During the spring of 2021, a coordinated multi-vessel effort was organized to study physical oceanography, marine geology and biology, and acoustics on the northeast United States continental shelf, as part of the New England Shelf Break Acoustics (NESBA) experiment. One scientific goal was to establish a real-time numerical model aboard the research vessel with high spatial and temporal resolution to predict the oceanography and sound propagation within the NESBA study area. The real-time forecast model performance and challenges are reported in this letter without adjustment or re-simulation after the cruise. Future research directions for post-experiment studies are also suggested.

Study on sedimentary facies and prediction of favorable reservoir areas in the Fuyu reservoir in the Bayanchagan area

Based on the study's thorough logging records from 74 wells, grain size analysis, spatial analysis of sand thickness and sand ratio, and pertinent regional geological data, a sedimentary microfacies analysis of the Bayanchagan area is conducted using one sand layer as a unit. In addition, the reservoir's microscopic characteristics are summarized, and the location of advantageous reservoir areas is predicted. The principal reservoir rock types in the research region are determined to be lithic arkose and feldspathic lithic sandstone, and reservoir physical attributes are also quite poor. Intergranular dissolution pores make up the bulk of reservoir space types, which also include primary pores, secondary dissolution pores, and micro-fractures. Additionally, the delta front and delta plain subfacies are recognized. Eight more sedimentary microfacies are found: sheet sand, estuary bar, underwater distributary channel, underwater distributary bay, overflow thin sand, floodplain, and distributary channel under water. In a sedimentary environment with water penetration, the entire reservoir was produced. The delta diversion plain deposit makes up the lower portion of the FIII, FII, and FI oil layer groups, while the delta front deposit makes up the top portion of the FI oil layer group. The reservoirs may be divided into three groups: type I reservoirs, type II reservoirs, and type III reservoirs by thorough examination of the facies, microstructure, mercury intrusion characteristics, and other criteria. Among these, type I and type II reservoirs with substantial thicknesses, which are favorable for hydrocarbon accumulation, are the main focus of favorable oil and gas area exploration. The investigation's conclusions are instructive for future research.

Landslide Susceptibility Evaluation Based on Potential Disaster Identification and Ensemble Learning

Catastrophic landslides have much more frequently occurred worldwide due to increasing extreme rainfall events and intensified human engineering activity. Landslide susceptibility evaluation (LSE) is a vital and effective technique for the prevention and control of disastrous landslides. Moreover, about 80% of disastrous landslides had not been discovered ahead and significantly impeded social and economic sustainability development. However, the present studies on LSE mainly focus on the known landslides, neglect the great threat posed by the potential landslides, and thus to some degree constrain the precision and rationality of LSE maps. Moreover, at present, potential landslides are generally identified by the characteristics of surface deformation, terrain, and/or geomorphology. The essential disaster-inducing mechanism is neglected, which has caused relatively low accuracies and relatively high false alarms. Therefore, this work suggests new synthetic criteria of potential landslide identification. The criteria involve surface deformation, disaster-controlling features, and disaster-triggering characteristics and improve the recognition accuracy and lower the false alarm. Furthermore, this work combines the known landslides and discovered potential landslides to improve the precision and rationality of LSE. This work selects Chaya County, a representative region significantly threatened by landslides, as the study area and employs multisource data (geological, topographical, geographical, hydrological, meteorological, seismic, and remote sensing data) to identify potential landslides and realize LSE based on the time-series InSAR technique and XGBoost algorithm. The LSE precision indices of AUC, Accuracy, TPR, F1-score, and Kappa coefficient reach 0.996, 97.98%, 98.77%, 0.98, and 0.96, respectively, and 16 potential landslides are newly discovered. Moreover, the development characteristics of potential landslides and the cause of high landslide susceptibility are illuminated. The proposed synthetic criteria of potential landslide identification and the LSE idea of combining known and potential landslides can be utilized to other disaster-serious regions in the world.

Applying lead (Pb) isotopes to explore mobility in humans and animals

Lead (Pb) isotopes provide a complementary method to other provenance tools for tracking the origin and movement of humans and animals. The method is founded in the geographic distribution of Pb isotope ratios. However, unlike the Sr isotope method that is closely linked to the lithology of underlying rocks, Pb more closely reflects the tectonic regimes. This makes it particularly pertinent to use in Britain as there is major tectonic boundary (the Iapetus Suture) that runs between Berwick-upon-Tweed and the Solway Firth providing a compositional boundary in Pb isotope domains that approximates to the geographic areas of Scotland versus England and Wales. Modern pollution makes it difficult to use modern floral or faunal samples to characterize biosphere variation, and so we use geological datasets to define isoscape variation and present the first Pb isotope map of Britain. We have validated the use of these data form biosphere studies using well provenanced samples. Reference fields of diagnostic compositions, are created in μ-T space and these have been used in a test case to assess the geographic origins of Neolithic animals in Great Britain.

A Plasma Transmitting Source for Borehole Acoustic Reflection Imaging

The detection depth of current borehole acoustic reflection imaging is only tens of meters without high resolution. This considerably limits its wide application in the identification and fine description of unconventional reservoirs and in the optimization of drilling trajectories. Increasing the directional energy from the transmitter to a geological structure is an excellent way to solve this issue. In this study, a plasma source with a parabolic reflector was introduced during borehole acoustic reflection imaging. First, an experimental system was built for testing the plasma source. Next, the acoustic-electrical characteristics and directional radiation of the source were studied using experiments and a numerical simulation. Finally, the advantages, disadvantages, and feasibility of the plasma-transmitting source were analyzed; some suggestions for further work on the source and its logging application were proposed. The experimental and simulation results show that the use of a plasma source with a parabolic reflector can increase the detection depth of borehole acoustic reflection imaging to hundreds of meters with high resolution. This is crucial in imaging the geological structures near boreholes and enhancing oil-gas exploration and development.

Excess Cr and Ni in top soil: Comparing the effect of geology, diffuse contamination, and biogenic influence

Chromium (Cr) and nickel (Ni) are among the elements that are most mined, processed and used in modern industry and society. A realistic estimate of the diffuse contamination that has left a footprint on soil during the last 200 years by worldwide industrialization requires recognition and assessment of the dominant natural and anthropogenic sources. The relations between geogenic, anthropogenic, and biogenic Cr and Ni sources are estimated from eight large-scale geochemical surveys, by comparing the cumulative distribution functions (CDF) of the elements in top- and sub soil using cumulative probability (CP) diagrams. This method makes it possible to estimate the effect of long-term diffuse contamination on soil without monitoring. The method offers a cheaper and more reliable method for estimating diffuse contamination at the continental to regional scale than classical monitoring methods. The impact of diffuse contamination can be recognized at the low-concentration end while strong local contamination is shown as a distort at the high-concentration end of the distribution. Chromium, due to its structural similarities with essential nutrients, shows a clear biological signal in the CP-diagram. The bio-adjustment of Cr and Ni limits the accuracy of the diffuse contamination estimates. Combining CDF analysis with spatial mapping provides insight into the dominant contamination processes that distort the top soil CDF relative to the sub soil CDF. For both elements, a diffuse contamination signal of <1 mg/kg is obtained for soils at the European scale. Agricultural soil is affected by contamination from farming practices and shows higher excess Cr and Ni in top soil than forest soil. Although the world has faced several centuries of industrial development and Cr and Ni are used "everywhere", this is not reflected in surface soil at the continental to regional scale. The regional distribution of both elements is dominated by natural sources and processes.

Subsurface microbial communities as a tool for characterizing regional-scale groundwater flow

Subsurface microbial community distribution patterns are influenced by biogeochemical and groundwater fluxes and may inform hydraulic connections along groundwater-flow paths. This study examined the regional-scale microbial community of the Death Valley Regional Flow System and evaluated whether subsurface communities can be used to identify groundwater-flow paths between recharge and discharge areas. Samples were collected from 36 sites in three groundwater basins: Pahute Mesa-Oasis Valley (PMOV), Ash Meadows (AM), and Alkali Flat-Furnace Creek Ranch (AFFCR). Microbial diversity within and between communities varied by location, and communities were separated into two overall groups that affiliated with the AM and PMOV/AFFCR basins. Network analysis revealed patterns between clusters of common microbes that represented groundwaters with similar geochemical conditions and largely corroborated hydraulic connections between recharge and discharge areas. Null model analyses identified deterministic and stochastic ecological processes contributing to microbial community assemblages. Most communities were more different than expected and governed by dispersal limitation, geochemical differences, or undominating processes. However, certain communities from sites located within or near the Nevada National Security Site were more similar than expected and dominated by homogeneous dispersal or selection. Overall, the (dis)similarities between the microbial communities of DVRFS recharge and discharge areas supported previously documented hydraulic connections between: (1) Spring Mountains and Ash Meadows; (2) Frenchman and Yucca Flat and Amargosa Desert; and (3) Amargosa Desert and Death Valley. However, only a portion of the flow path between Pahute Mesa and Oasis Valley could be supported by microbial community analyses, likely due to well-associated artifacts in samples from the two Oasis Valley sites. This study demonstrates the utility of combining microbial data with hydrologic, geologic, and water-chemistry information to comprehensively characterize groundwater systems, highlighting both strengths and limitations of this approach.

Spatio-temporal landslide inventory and susceptibility assessment using Sentinel-2 in the Himalayan mountainous region of Pakistan

The 2005 Kashmir earthquake has triggered widespread landslides in the Himalayan mountains in northern Pakistan and surrounding areas, some of which are active and are still posing a significant risk. Landslides triggered by the 2005 Kashmir earthquake are extensively studied; nevertheless, spatio-temporal landslide susceptibility assessment is lacking. This can be partially attributed to the limited availability of high temporal resolution remote sensing data. We present a semi-automated technique to use the Sentinel-2 MSI data for co-seismic landslide detection, landslide activities monitoring, spatio-temporal change detection, and spatio-temporal susceptibility mapping. Time series Sentinel-2 MSI images for the period of 2016-2021 and ALOS PALSAR DEM are used for semi-automated landslide inventory map development and temporal change analysis. Spectral information combined with topographical, contextual, textural, and morphological characteristics of the landslide in Sentinel-2 images is applied for landslide detection. Subsequently, spatio-temporal landslide susceptibility maps are developed utilizing the weight of evidence statistical modeling with seven causative factors, i.e., elevation, slope, geology, aspect, distance to fault, distance to roads, and distance to streams. The results reveal that landslide occurrence increased from 2016 to 2021 and that the coverage of areas of relatively high susceptibility has increased in the study area.

RecMin Variograms: Visualisation and Three-Dimensional Calculation of Variograms in Block Modelling Applications in Geology and Mining

Variogram calculation is a fundamental tool for studying ore grade data in mineral deposits. It allows the discovery of hidden structures within the data and preferential directions of mineralization where the geological continuity is longer. The variogram allows us to classify samples and to define both the search radii for interpolation and the use of kriging as an interpolation and resource classification method. It is not difficult to use it in one dimension; complexity increases in two dimensions as the necessity to search for possible grade anisotropies in all directions arises. Three-dimensionally it is even more difficult to try to define the parameters of lag, bandwidth, and tolerances that define the data of the variogram calculation algorithm. There are rules of thumb to help in the development, but a trial-and-error approach is used in order to find enough sample pairs to allow the generation of variograms truly representative of the data. In this paper, two strategies are shown to help in variogram construction, the use of variogram maps and the graphical representation of the pair search areas (cones or pencils). The freeware tool RecMin Variograms has been developed and is freely available for download at its website; it is easy to learn and use. R code based on RGeostats libraries is used to check the operation and results of RecMin Variograms. Applying geostatistics to mineral deposits is essential to know the areas with the highest grades, thus allowing exact planning of future mining exploitation and minimizing mine footprint and environmental impact.

Background clutter amplitude and frequency of GPR signals to analyse water content in sedimentary deposits: Urban infrastructure environment

Soil site studies are crucial in the analysis of seismic hazard in populated areas. This study focusses on the use of the Ground Penetrating Radar as a non-destructive geophysical method to analysis the water content of a sedimentary basin of a local urban area in Cervantes Parks in Barcelona city. Main objective of this work is to understand further the local seismic soil site, and analysis the background clutter amplitude and frequency of the GPR signal applied on the seasonal changes of the underground water content. Changes produces in the GPR signal could be associated to the changes of the ground material due to the existence of water content and water flow, which influence the grain size distribution of the soil characterisation. Previously, several methodologies have been applied to determine the changes of the ground material due to the existence of water content and most importantly effect of the seasonal changes on the soil characterisation. GPR has been applied as a new technology and non-invasive to further analysis water content in shallow geology. Methodology applied on this study compromised in four different phases; Two seasonal data collection using 100 MHz centre frequency shielded antenna in both dry and wet season, radar images are proceeded with common post-processing approaches, following more innovative processing approach based on the Fast Fourier Transform (FFT) method in order to analysis background clutter amplitude and frequency spectrum to achieve an accurate interpretation of underground water content activities, in conclusion a comparative study of the results driven from radar images are elaborated considering historical knowledge. Results show that GPR is an efficient technique to analysis water content invasively considering low frequency antennas to achieve deeper penetration depth in sedimentary deposits, and predict shifting and increasing of the underground streams due to changes in weather conditions. Results could contribute to the enhancing local seismic site behaviour in populated areas considering continuous monitoring of underground water activities in sedimentary basin sites.

The biogeochemical cycling of chlorine

Chlorine has important roles in the Earth's systems. In different forms, it helps balance the charge and osmotic potential of cells, provides energy for microorganisms, mobilizes metals in geologic fluids, alters the salinity of waters, and degrades atmospheric ozone. Despite this importance, there has not been a comprehensive summary of chlorine's geobiology. Here, we unite different areas of recent research to describe a biogeochemical cycle for chlorine. Chlorine enters the biosphere through volcanism and weathering of rocks and is sequestered by subduction and the formation of evaporite sediments from inland seas. In the biosphere, chlorine is converted between solid, dissolved, and gaseous states and in oxidation states ranging from -1 to +7, with the soluble, reduced chloride ion as its most common form. Living organisms and chemical reactions change chlorine's form through oxidation and reduction and the addition and removal of chlorine from organic molecules. Chlorine can be transported through the atmosphere, and the highest oxidation states of chlorine are produced by reactions between sunlight and trace chlorine gases. Partial oxidation of chlorine occurs across the biosphere and creates reactive chlorine species that contribute to the oxidative stress experienced by living cells. A unified view of this chlorine cycle demonstrates connections between chlorine biology, chemistry, and geology that affect life on the Earth.

A Review of Low-Impact Development Factors Affecting Managed Aquifer Recharge

Low-impact development (LID) technology for stormwater control has a number of forms, some of which relate to managed aquifer recharge to provide adequate safe water to communities. Stormwater collected through LID for managed aquifer recharge shifts water quantity and quality effects from surface waters to groundwater. Factors affecting quantity and quality of recharge influence and are influenced by state/local land development policy, state/local groundwater policy, regulation and codes and climate change effects, as well as pretreatment requirements. Groundwater quality effects of untreated stormwater infiltration by LID in a range of hydrogeologic settings are not well understood. Site selection for LID will include hydrogeologic considerations, onsite footprint and construction factors. Cost of the technology has a wide range of typically low-cost options. Lessons learned include: matching technology to hydrogeologic setting; state/local policy should serve to avoid hydraulic and pollutant effects, particularly high water impacts; representative groundwater monitoring adds safeguard to water supply; and LID systems designs should consider life cycle costing including vulnerable geology, not just low installation cost.