Search Results (11)

On the outskirts of the Pinios dam reservoir (Ilia Regional Unit, Greece), a water treatment plant serves the water supply needs of the surrounding municipalities, in which high concentrations of Fe and Mn, before treatment, have been observed. The main purpose of this research was to investigate the mechanism of increased iron (Fe) and manganese (Mn) levels in the reservoir of the Pinios dam, which impacts its water treatment plant operation. A wide range of hydrochemical and sedimentological analyses were conducted over a hydrological year, focusing on the spatial and temporal distribution of Fe and Mn in both water and sediment samples across the established research monitoring stations. Sediment samples from the reservoir’s bottom revealed predominantly fine-grained material, rich in total organic carbon, with elevated Mn and Fe oxide levels. Significant seasonal variations in Fe and Mn levels were also discovered, with higher Mn levels observed in the anoxic bottom waters of the reservoir during the dry season, attributed to the reduced conditions favoring Mn oxide dissolution over Fe. Conversely, during the wet season, a homogenization of metal concentrations throughout the water column was observed due to increased oxygenation and freshwater inflow. These outcomes were confirmed by the hydrochemical analysis, indicating that the redox conditions, pH, and temperature, as well as the presence of organic matter, significantly influence the mobility and bioavailability of these metals in the reservoir. The findings of this study clarify that the high concentration of Fe and Mn can be linked to the mineral composition of the upstream Neogene and flysch formations in the study area. As these formations are affected by geological weathering, they tend to enrich the streams, through soil erosion and runoff processes, with metals like Fe and Mn, which are eventually transported into the dam reservoir. This study highlights the critical influence of lithological, sedimentological, and hydrological factors on the redox conditions and seasonal stratification that govern the behavior of Fe and Mn concentrations and mobility in dam reservoirs. These findings are critical for informing water resource management practices and dam infrastructure operators and developing effective environmental conservation strategies in similar cases. Full article

The adsorption of As(V) and As(III) (0.01–1 mM) on a calcined oxidic lithologic material substrate with pH-dependent surface variable charges, chemically modifiable, was investigated. The substrate was prepared via thermal treatment using a natural lithologic material rich in amphoteric oxides of Fe, Al, Mn and Ti. The calcined substrate was treated with acid media (HCl 0.1) to homogenize the positive charge density on the oxide surface via oxide protonation so that anion adsorption would be favored. A batch experiment was performed on the acid-treated substrate (activated) and non-activated substrate. L-type isotherms were obtained, which fit the Freundlich model. Isotherm constants showed that there was a greater affinity between the activated substrate and As(V) (K = 10.58) compared to As(III) (K = 5.45). The adsorption capacity of the activated substrate was two times greater than that of the non-activated substrate, As(V) (K_act = 10.58 and K_noact = 5.45) vs. As(III) (K_act = 5.45 y K_noact = 2.44), which was due to the greater positive charge density on the activated surface, created by the protonation of the surface oxides. Protons were liberated during the adsorption reaction (As(V): 2.17 × 10⁻³ and As(III): 0.96 × 10⁻³ mmol/mL). The forms H₂AsO₄⁻ and H₃AsO₃ deprotonated when adsorbed by the surface groups $\mathrm{M}-\mathrm{O}{\mathrm{H}}_2^{+}$ (M: Fe, Al). Kinetic data showed a second-order process for As(V) adsorption and a first-order process for As(III) adsorption. The adsorption rate on the activated substrate was two times greater compared with the non-activated substrate: As(V) (k_act = 3.78 × 10⁻⁵ L/mg·min and k_noact = 2.16 × 10⁻⁵ L/mg·min) vs. As(III) (k_act = 0.055 h⁻¹ and k_noact = 0.027 h⁻¹). The tested substrate is potentially useful as a low-cost natural material for arsenic removal from contaminated water. Full article

Water treatment necessitates the sustainable use of natural resources. This paper focuses on the characterization of three oxidic lithological materials (OLMs) with the aim of utilizing them to prepare calcined adsorbent substrates for ionic adsorption. The three materials have pH levels of 7.66, 4.63, and 6.57, respectively, and organic matter contents less than 0.5%. All of the materials are sandy loam or loamy sand. Their electric conductivities (0.18, 0.07, and 0.23 dS/m) show low levels of salinity and solubility. Their CEC (13.40, 13.77, and 6.76 cmol(+)kg) values are low, similar to those of amphoteric oxides and kaolin clays. Their aluminum contents range from 7% up to 12%, their iron contents range from 3% up to 7%, their titanium contents range from 0.3% to 0.63%, and their manganese contents range from 0.007% up to 0.033%. The amphoteric oxides of these metals are responsible for their ionic adsorption reactions due to their variable charge surfaces. Their zirconium concentrations range from 100 to 600 mg/g, giving these materials the refractory properties necessary for the preparation of calcined adsorbent substrates. Our XRD analysis shows they share a common mineralogical composition, with quartz as the principal component, as well as albite, which leads to their thermal properties and mechanical resistance against abrasion. The TDA and IR spectra show the presence of kaolinite, which is lost during thermal treatments. The results show that the OLMs might have potential as raw materials to prepare calcined adsorbent substrates for further applications and as granular media in the sustainable treatment of both natural water and wastewater. Full article

High-alumina (HA) mare basalts play a critical role in lunar mantle differentiation. Although remote sensing methods have speculated their potential presence regions based on sample FeO and TiO₂ compositions, the location and distribution characteristics of HA basalts have not been provided. In this study, the compositions of exposed rocks in Mare Imbrium were determined using Lunar Reconnaissance Orbiter (LRO) Diviner oxides and Lunar Prospector Gamma-Ray Spectrometer (LP-GRS) Thorium (Th) products. The exposed HA basalts were identified based on laboratory lithology classification criteria and Al₂O₃ abundance. The HA basalt units were mapped based on lunar topographic data, and their morphological geological characteristics were calculated based on elevation data. The results show that there are 8406 HA basalt pixels and 17 original units formed by volcanic eruptions in Mare Imbrium. The statistics of their morphology characteristics show that the HA basalts are widely distributed in the northern part of Mare Imbrium, and their compositions have a large range of variation. These units have different area and volume, and the layers formed were discontinuous. The characteristic analysis shows that the aluminum-bearing volcanic activities in Mare Imbrium were irregular. The eruptions of four different source regions occurred in three phases, and the scale and extent of the eruptions were different. The results in this study provide reliable evidence for the heterogeneity of the lunar mantle and contribute valuable information to the formation process of early lunar mantle materials. Full article

The mining sector actively seeks to improve operational processes and manage residual materials, especially in areas used for heap leaching disposal. The flowability of residues following deposition can have an impact on storage capacity, productivity, and workers’ safety. In this study, an artificial neural network (ANN) approach is applied to evaluate the accuracy of three models in predicting the flowability of spent heap leach when it is discharged into the dump, considering three or five segregation categories. The models with five categories exhibited the highest level of accuracy, with learning responses ranging from 72% to 78% and predictions from 88% to 96%. These indicate that ANN models have the potential to be a decision-making tool for the discharge strategy in the dump. Modules containing lithologies such as clays and phyllosilicates exhibited increased susceptibility to separation due to their water retention capacity, which negatively impacted their permeability and conductivity. The decomposition of iron oxide, along with clays and low hardness, led to the formation of fines, limited permeability, and inadequate solution drainage. Rock competence and low formation of fines provide good permeability, and better drainage conditions for the solution, and help maintain the stability of the spent heap leach in the dump. Full article

The Tarim Basin, a significant region of coal-derived gas generation in China, has widely dispersed coal measure source rocks, especially in the Kuqa Depression. The typical coal measure strata from the Kuqa River and Kapushaliang River sections in the Kuqa Depression were systematically sampled. According to a conventional geochemical analysis (including materials and lithology), a total of 25 typical coal measure source rock samples were chosen for chromatography and chromatography–mass spectrometry examination. It was demonstrated that there were significant discrepancies in the coal source rock samples, particularly the coal rock from the Kuqa River section and the Kapushaliang River section. The specific performance of the Kuqa River section was characterized by a high Pr/Ph ratio (up to 9.29), a low gammacerane ratio, a low abundance of tricyclic terpane, and an “L”-type distribution of regular steranes, all of which are consistent with the properties of humic coal found in freshwater lakes that have undergone partial oxidation. The Kapushaliang River section, by contrast, exhibited a low Pr/Ph ratio (<1.0), a high gammacerane ratio, a concentration of tricyclic terpane comparable to that of hopane, and a distribution of regular steranes in a “V” shape, all of which indicate a strongly reduced saline water environment. Additionally, the degree of thermal evolution is not the key factor resulting in the above biomarker diversity within the CSRs, which was supported by the poor correlation between the maturity parameters (Ro%, Tmax °C), the sedimentary environment-related parameters (such as Pr/Ph and Ga/C₃₁H), and the biogenic-related parameters (such as ∑tricyclic terpane/∑ hopane and ∑sterane/∑hopane). A comparative analysis suggested that transgression-related changes in the redox conditions and parent materials triggered the biomarker diversity within the CSRs, resulting in a large difference in the hydrocarbon-forming parent materials between the two abovementioned outcrop sections. These might provide some insight for hydrocarbon exploration from CSRs, which have been attracting increasing attention in China, with proven coal reserves are ranked first in the world. Full article

The development model of the coal-measure source rock may be different from that of the lacustrine source rock. The depositional environment of the coal-measure source rock is dominated by weak oxidation and weak reduction, and the majority of the organic material originates from terrestrial higher plants. Taking the Jurassic coal-measure source rock in the Kuqa Depression as the research object, the geochemical characteristics of the source rock are comprehensively analyzed, the primary controlling elements of source rock development are made clear, and the development model of the coal-measure source rock is established. This study contributes to the field of source rock prediction and oil and gas exploration. The lithology of the coal-measure source rock in the Kuqa Depression is mainly mudstone, carbonaceous mudstone, and coal, which are medium- to good-quality source rocks, and the organic matter type is mainly II₂ and III. Terrestrial organic matter is a key factor in controlling the formation of coal-measure source rocks, and the sedimentation rate also has a certain influence. The redox degree of the depositional environment, water salinity, and clay mineral content has little influence on the development of coal-measure source rocks. By integrating the main control factors, the development model of the coal-measure source rock is established. It is considered that the development model and distribution characteristics of the coal-measure source rock are different from the traditional understanding of lacustrine source rocks, and it is pointed out that the coal-measure source rock in the gentle slope zone is more developed than the sag area. Full article

This work evaluates phosphate and nitrate ion adsorption from aqueous solutions on calcined adsorbent substrates of variable charge, prepared from three granulometric fractions of an oxidic lithological material. The adsorbent material was chemically characterized, and N₂ gas adsorption (BET), X-ray diffraction, and DTA techniques were applied. The experimental conditions included the protonation of the beds with HCl and H₂SO₄ and the study of adsorption isotherms and kinetics. The lithological material was moderately acidic (pH 5) with very little solubility (electrical conductivity 0.013 dS m⁻¹) and a low cation exchange capacity (53.67 cmol (+) kg⁻¹). The protonation reaction was more efficient with HCl averaging 0.745 mmol versus 0.306 mmol with H₂SO₄. Likewise, the HCl-treated bed showed a better adsorption of PO₄⁻³ ions (3.296 mg/100 g bed) compared to the H₂SO₄-treated bed (2.579 mg/100 g bed). The isotherms showed great affinity of the PO₄⁻³ ions with the oxide surface, and the data fit satisfactorily to the Freundlich model, suggesting a specific type of adsorption, confirmed by the pseudo-second-order kinetic model. In contrast, the nitrate ions showed no affinity for the substrate (89.7 µg/100 g for the HCl-treated bed and 29.3 µg/100 g bed for the H₂SO₄-treated bed). Amphoteric iron and aluminum oxides of variable charges present in the lithological material studied allow for their use as adsorbent beds as an alternative technique to eliminate phosphates and other ions dissolved in natural water. Full article

The geological context of this study is established in the iron oxide-copper-gold (IOCG) deposit of Sossego (Canaã dos Carajás, Brazil), where hydrothermal alterations in shear zones concentrated the metals of interest and added new characteristics to the metavolcanic-sedimentary and granite rocks. The mineral transformation of rocks by hypersaline fluids enriched in metals and silica also modifies some metallurgical properties, such as abrasiveness. Special bench tests on rock drill cores are used in mapping the abrasiveness of rocks, with the Bond abrasion test being more commonly used in the mining industry, but it has a restrictive sampling protocol and mass requirement for geometallurgical studies. As a counterpoint, the test of the Laboratoire Central des Ponts et Chaussées/Central Laboratory of Bridges and Roads (LCPC) requires a smaller amount of fine material and a finer granulometric range. The study on the use of LCPC was implemented in 40 samples, using Bond Ai as a reference. The results showed a strong correlation between both methodologies (R² = 95%), validating the use of LCPC to quantify abrasiveness in the Sossego mine. It was also possible to classify the most abrasive lithologies. Full article

Volcanic tuffs have a historical tradition of usage in Northern Hungary as dimension stones for monumental construction, Ottoman architecture, common dwellings, etc., admirable at its best in the medieval castles of Eger and Sirok. This research explores tuff deterioration in the castle walls, dealing with the mineralogical composition, microstructure, trace-element geochemistry, and microporosity of the surface weathering products and the near-surface stone substrate. The classic microscopic and mineralogical techniques–optical microscopy, SEM-EDS, and XRD–were supported by ICP-MS and nitrogen adsorption analyses. The textures and mineral assemblages of the tuffs are partly diverse, and so are the weathering characteristics, although including common features such as secondary crystallization of gypsum, swelling clay minerals, and iron oxides-hydroxides; deposition of airborne pollutants, i.e., carbon particles and heavy metals; formation of crusts and patinas; decreased surface microporosity. Nonetheless, the entity of deterioration varies, in relation to air pollution–involving changing emissions from road and rail transport–and the specific tuff texture, porosity, and durability–affecting pollutant absorption. The studied stone monuments offer the possibility to examine materials with analogue composition and petrogenesis but utilized in different environmental contexts, which allow pointing out the environmental and lithological constraints and cause-effect relationships related to surface weathering. Full article

The Pyrenean range (NE Iberian Peninsula) has some favourable lithological and climatic conditions (iron-rich parent materials and udic moisture regimes) for the formation of acid sulfate soils (ASS) that have not been reported on from the region until now. The analyses of a drained peat bog near València d’Àneu revealed a pH (1:2.5) of 3.7. We hypothesize that it contained sulfidic materials that were oxidized during drainage, which could have caused its acidification. The main goal of this study is to understand the characteristics and the potential acidity of these organic soils and the consequences that this could generate in the current environment. In order to do so, several profiles were described and sampled in the field for chemical and micromorphological analyses. The results show that the oxidation of the newly formed pyrite in the soil or pyrite contained in the Cambro–Ordovician parent material was responsible for the low pH and high electrical conductivity (EC). The soils still contain sulfidic materials at present, which could be oxidized in the future, with the consequent risk for water quality. The results will be useful to evaluate the risk of other peats in the Pyrenees becoming acid sulfate soils if drained. Full article