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During surface coal mining, large amounts of overburden waste materials, known as spoils, are excavated and dumped, creating massive heaps. The sustainable management of these areas is a global priority, but a comprehensive geotechnical characterization has not yet been achieved due to limited research on the spoils' geotechnical properties. This study conducts an advanced statistical analysis of lignite mine spoil materials from a large heap in Greece to determine suitable probability distributions. Five distributions - normal, lognormal, Weibull (2 and 3 parameters), and Gamma - were evaluated, considering the high variability of spoil material properties. The lognormal and Weibull distributions were found to best fit most geotechnical parameters, except for cohesion, which showed an uncommon distribution. In some cases, the normal distribution can be used for a simplified analysis. The findings can guide the analysis of spoil materials, as advanced numerical and stochastic methods are essential for robust geotechnical design. [ABSTRACT FROM AUTHOR]

As the world transitions away from coal, vast areas of closed coal mines and waste dumps must be appropriately reclaimed. One critical element for these areas’ safety is slope stability, given the massive slopes of these mines and dumps. This work examines the effect of extreme rainfall on coal mines’ slopestability by incorporating unsaturated soil mechanics principles in a practical way. Past extreme rainfall events recorded for a Greek lignite mining area were used, and climate projections concluded that this intensity is not expected to change. Then, rainfall infiltration was simulated using the Finite Element Method; a typical slope was employed concerning a lignite mining excavation of 200m height and 14° inclination on fine-grained soils. Finally, the stability was calculated using the Limit Equilibrium Method. Rainfall infiltration caused the Safety Factor to decrease, leading to failure. The groundwater rose at theslope’s face from the slope’s toe upwards and led to the development of a smaller and more local than the initial (before rainfall) sliding surface with a lower Safety Factor. Although this is a smaller surface than the initial one, it is still more than 50m high, proposing a significant hazard with severe consequences for the area.

Especially in recent years, the study of landslide phenomena is considered as very important because of the effects of climate change. The aim of this paper is to examine the stability of the slope located in Miacher Nagar village along the Hunza River (HR), using the Limit Equilibrium Method (LEM). The Miacher slope rises to a height of 900 m from the foot of the Hunza River and has a base angle of 50 degrees. Meta-sediments and quaternary recent glaciated deposits make up the majority of the slope's composition. The slope movement of Miacher was first triggered in 1995, and was further triggered in 2010 and 2013. The slope was geologically, geomorphologically, geotechnically and geochemically investigated as well as modeled by Slope/w to determine the safety factor. Soil samples were analyzed for their geotechnical, geological and geomorphological properties. The Limit Equilibrium Method (LEM) was employed in this study to analyze the Factor of Safety (FOS) of the slope, based on assumptions of the Morgenstern and Price, Ordinary, Janbu and Bishop Methods, using the Slope/w software. Various factors, including pore water pressure, unit weight, cohesion, angle of internal friction and overburden, were examined by analyzing different scenarios. The findings showed that an increase in cohesion and angle of internal friction resulted in an increase in FOS, whereas an increase in unit weight and overburden caused a decrease in FOS. The influence of pore water pressure was positive to a certain extent, but a further increase led to a significant reduction in FOS. The results showed that the Miacher slope is currently stable, as all FOS values were greater than one, based on the existing strength parameters and simulated results obtained using Slope/w. [ABSTRACT FROM AUTHOR]

Clays have been applied for centuries by people for many uses. From pottery to medicine, clays and clay minerals constitute part of individuals' daily routines. Natural fine-grained earth material, commonly found at Xi beach coastal area of Lixouri in Kefalonia island, was used during the last few decades by local people as well as from tourists for pelotherapy, even though this material has never been examined for its suitability for this use. This work was conducted aiming to characterize this material and determine if it is harmless and beneficial for therapeutic purposes or skin care. Field work revealed that the material is not homogenous and, therefore, some of its parts could be characterized as suitable, non-suitable or even harmful. The collected samples from Kefalonia were characterized according to their petrographic and chemical features using Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF) and Transmission Electron Microscopy (TEM). Moreover, the microbial burden of the material was assessed analyzing the bacterial and fungi load. This study indicates that this geomaterial can be suitable for natural mud/peloid applications, but only in some parts of this area. [ABSTRACT FROM AUTHOR]

Sustainable serpentine/polyamide nanocomposite (SP/PAM) was fabricated using malicious mining (serpentine chrysotile, SP Ctl) and industrial (polyamide, PA6) wastes via the electro-spinning technique. Before fabrication, the fibrous nature of Ctl was demolished through intensive grinding into nano-fractions. The successful impregnation of Ctl within PA6 via the electro-spinning technique at fixed ratios of precursor raw materials in the dissolving agent (7.5/92.5% SP/PA wt/wt solid/solid) created an internal network structure within the polymer fibers by molecular self-assembly. SP/PAM showcased its prowess in tackling the remediation of diverse dyes and Fe(III) from synthetic solutions in a batch system. Based on correlation coefficient outcomes (R2 ≈ 0.999), the pseudo-second-order equation justified the sorption data in an adequate way for all contaminants. In addition, intra-particle diffusion was not the only driving factor in the sorption process. Similarly, the Langmuir equation with maximum removal capacity (qmax) 5.97, 4.33, and 5.36 mg/g for MO, MB, and Fe(Ⅲ), respectively, defined the sorption data better than Freundlich. [ABSTRACT FROM AUTHOR]

Research attempts on biomass use constitute a response to the growing demand for sustainable and low-cost energy from renewable sources. Hence, the sustainable use of Posidonia oceanica (PO) waste as a material for biomass to produce green energy is being considered in many countries in the Mediterranean region. PO meadows are considered as the main type of sea flora in the Greek coasts. PO can extract biomass from nearby ecosystems of the coastal zone, either directly through the transportation of disposed non-living leaves or indirectly via benthic organisms. The aim of this study is to investigate the use of PO waste derived from Kefalonia Island (Greece) as a biomass source. PO samples were collected around the island, and they were mineralogically and microstructurally analyzed. In addition, physicochemical, chemical, and thermogenic tests were performed in order to obtain the optimum and most completed characterization of the material. Based on the results, cellulose seems to be the main structural component of PO, which also seems to determine their behavior. PO presents microscopic similarities to other lignocellulosic materials which composition is made of carbonates, lignin, extractives, and minerals. Ash and moisture content constitute the two critical parameters that are responsible for the energy differences of each biomass. The outcome of this study shows the potential use of PO wastes as an interesting source for energy production. [ABSTRACT FROM AUTHOR]

Coastal environments are highly recognized for their spectacular morphological features and economic activities, such as agriculture, maritime traffic, fishing, and tourism. In the context of climate change and the evolution of physical processes, the occurrence of intense natural phenomena adjacent to populated coastal areas may result in natural hazards, causing human and/or structural losses. As an outcome, scientific interest in researching and assessing multi-hazard susceptibility techniques has increased rapidly in an effort to better understand spatial patterns that are threatening coastal exposed elements, with or without temporal coincidence. The islands of Milos and Thira (Santorini Island) in Greece are prone to natural hazards due to their unique volcano-tectonic setting, the high number of tourist visits annually, and the unplanned expansion of urban fabric within the boundaries of the low-lying coastal zone. The main goal of this research is to analyze the onshore coastal terrain's susceptibility to natural hazards, identifying regions that are vulnerable to soil erosion, torrential flooding, landslides and tsunamis. Therefore, the objective of this work is the development of a multi-hazard approach to the South Aegean Volcanic Arc (SAVA) islands, integrating them into a superimposed susceptibility map utilizing Multi-Criteria Decision-Making (MCDM) analysis. The illustrated geospatial workflow introduces a promising multi-hazard tool that can be implemented in low-lying coastal regions globally, regardless of their morphometric and manmade characteristics. Consequently, findings indicated that more than 30% of built-up areas, 20% of the transportation network, and 50% of seaports are within the high and very high susceptible zones, in terms of the Extended Low Elevation Coastal Zone (ELECZ). Coastal managers and decision-makers must develop a strategic plan in order to minimize potential economic and natural losses, private property damage, and tourism infrastructure degradation from potential inundation and erosion occurrences, which are likely to increase in the foreseeable future. [ABSTRACT FROM AUTHOR]

This article presents, for the first time, the study of diabases from various ophiolite complexes from Greece and Cyprus to identify their performance as concrete aggregates. Within this scope, in the first step, diabase samples from four selected ophiolite complexes of Greece (Veria-Naousa, Edessa and Guevgueli) and Cyprus (Troodos) were collected in order to estimate their suitability as concrete aggregates by means of their petrographic and physicochemical characteristics. In the next step, concrete specimens were prepared and their mechanical strength was measured in order to investigate their mechanical performance. Additionally, their petrographic characteristics in relation to the mechanical strength of the created concretes were investigated for the first time. Concrete specimens prepared by employing diabases from the Veria-Naousa and Guevgueli complexes as aggregates were reckoned as the most durable ones in contrast to those derived from the Edesssa complex and even more so than those from Cyprus, with the latter containing the most altered diabases (rodingitised). The overall conclusion of this research is that the engineering properties of the aggregates were dependent on their petrographic characteristics and hence they influenced the final mechanical behaviour of each produced concrete. [ABSTRACT FROM AUTHOR]

This paper presents an investigation of naturallyoccurring CO2 emissions from the Florina natural analoguesite in Greece. The main objective was to interpretpreviously collected depth sounding data, convert theminto surfaces, and use them as input to develop, for thefirst time, 3D geological models of the Florina basin. Byalso locating the extent of the aquifer, the location of theCO2 source, the location of other natural CO2 accumulations,and the points where CO2 reaches the surface, wewere able to assess the potential for CO2 leakage. Geologicalmodels provided an estimate of the lithological compositionof the Florina Basin and allowed us to determinepossible directions of groundwater flow and pathways ofCO2 flow throughout the basin.Important modelling parameters included the spatial positionsof boundaries, faults, and major stratigraphic units(which were subdivided into layers of cells). We used variousfunctions in Petrel software to first construct a structuralmodel describing the main rock boundaries.We thendefined a 3D mesh honouring the structural model, andfinally we populated each cell in the mesh with geologicproperties, such as rock type and relative permeability.According to the models, the thickest deposits are locatedaround Mesochorion village where we estimate thataround 1000 m of sediments were deposited above thebasement. Initiation of CO2 flow at Florina Basin couldhave taken place between 6.5 Ma and 1.8 Ma ago. The NESWoriented faults, which acted as fluid flow pathways,are still functioning today, allowing for localised leakageat the surface. CO2 leakage may be spatially variable andepisodic in rate. The episodicity can be linked to the timingof Almopia volcanic activity in the area.