Weathering Research Articles

Comparison of the Characteristics of Baekak(chalk) and Hobun(shell) Pigment for Dancheong based on Natural Raw Materials

Calcium carbonate white pigments were manufactured by classifying them into Baekak(chalk) and Hobun(Shell) according to the type of natural raw material, and their material characteristics were analyzed. Their performances were compared by evaluating their weather resistance, antifungal activity, and flame retardancy. The main components of Baekak pigments are calcite and dolomite, and those of Hobun pigments a re calcite and a ragonite. Depending on the raw material, the specific factors identified are Mg from the mineral composition of Baekak pigments, and P and S from the protein composition of Hobun pigments. The particle shape of the pigment shows a crystal structure unique to minerals in the case of Baekak pigments, but the Hobun pigments are classified into plate-shaped or columnar structures depending on the raw material and are in an aggregated state with a large specific surface area. While the absorption amount of Baekak pigments made from limestone and dolomite is similar, that of Hobun pigments shows differences depending on the raw material, with the absorption amount being high in the order of oyster > cockle > clam. As a result of the color analysis, both the Baekak and the Hobun pigments had L* values of over 90 and opacity of over 90, indicating good whiteness and painting workability. As a result of the accelerated weathering test, the final color difference value(ΔE) was less than 2.02, which was difficult to recognize with the naked eye, and the Hobun pigment showed superior color and film stability compared to the Baekak pigment. As a result of the antifungal test, all calcium carbonate-based white pigments showed high preventive effects against decay fungi, and among them, the pigment made from clams and cockles showed excellent antiseptic properties. In addition, the pigment made from clams and cockles has been shown to have flame retardant properties, and it is expected that it will contribute to enhancing the preservation of organic cultural heritage when applied to it.

Applicability of Multi-coating for Preserving Surfaces of Outdoor Bronze sculptures

The wax used for surface coating of outdoor bronze sculptures is prone to material aging, surface cracking, and whitening due to environmental changes and air pollutants, leading to a shortened coating treatment cycle. To improve these material limitations, I explored the possibility of applying a multi-coating method that uses both acrylic resin and wax in an outdoor environment in Korea. The results of the experiment showed that the multi-coating method significantly improved the durability of the coating layer, weather resistance against external degrading factors, corrosion prevention ability, and contact angle, etc. compared to the existing wax-only coating method, and the rate of color change (ROC) was low, proving its stability. Especially, the double-coating method of acrylic resin and wax using acrylic urethane and Bowling Alley Wax® (acrylic resin + wax) was found to be the most stable coating method among the multi-coating methods. According to such results, I found that the multi-coating method can be proposed as a new surface coating treatment method that can secure long-term preservation of bronze sculptures and preserve their original form even in outdoor environments in Korea, by remedying the shortcomings of the wax-only coating.

Slope Stability Analysis of Open-Pit Mine Considering Weathering Effects

Weathering processes gradually alter the physical and mechanical attributes of slope materials, weakening the structural integrity and stability of slopes. This paper presents an in-depth analysis of slope stability in an open-pit mine, emphasizing the pivotal role of weathering effects in determining slope stability. To accurately capture the impact of weathering on slope stability, a comprehensive analysis model was developed, incorporating field observations, laboratory testing, and numerical simulations. The effects of weathering on the mechanical properties of black shale were studied through extensive laboratory tests. The uniaxial compressive strength, shear strength, and modulus of elasticity significantly decreased with increasing weathering, indicating a heightened vulnerability to slope failure. The correlation function between mechanical parameters and weathering time was obtained, providing the basis for evaluating the stability of mine slopes. It was found that more severe weathering conditions were strongly correlated with elevated risks of slope failure, including landslides and collapses. Based on these findings, practical recommendations are provided for slope reinforcement and management strategies, aimed at mitigating slope failure risks and ensuring the safe and efficient operation of the mine. By incorporating weathering effects into slope stability analysis, mine operators can make informed decisions that account for the dynamic nature of slope materials and their susceptibility to weathering, thereby improving overall mine performance and safety.

Impact of Assimilating Geostationary Interferometric Infrared Sounder Observations from Long- and Middle-Wave Bands on Weather Forecasts with a Locally Cloud-Resolving Global Model

The Geostationary Interferometric InfraRed Sounder (GIIRS) provides a novel opportunity to acquire high-spatiotemporal-resolution atmospheric information. Previous studies have demonstrated the positive impacts of assimilating GIIRS radiances from either long-wave temperature or middle-wave water vapor bands on modeling high-impact weather processes. However, the impact of assimilating both bands on forecast skill has been less investigated, primarily due to the non-identical geolocations for both bands. In this study, a locally cloud-resolving global model is utilized to assess the impact of assimilating GIIRS observations from both long-wave and middle-wave bands. The findings indicate that the GIIRS observations exhibit distinct inter-channel error correlations. Proper inflation of these errors can compensate for inaccuracies arising from the treatment of the geolocation of the two bands, leading to a significant enhancement in the usage of GIIRS observations from both bands. The assimilation of GIIRS observations not only markedly reduces the normalized departure standard deviations for most channels of independent instruments, but also improves the atmospheric states, especially for temperature forecasting, with a maximum reduction of 42% in the root-mean-square error in the lower troposphere. These improvements contribute to better performance in predicting heavy rainfall.

Blends of polydimethylsiloxane-based polyurethane and poly (propylene glycol)-based polyurethane with co-continuous structures: Morphology evolution, synergistic effects and application in strain sensors

Blending is an effective way to improve properties of rubbers and develop new materials, so more than 75 % of the rubber consumption in the world is rubber blend. However, blending of thermoplastic elastomers has not yet been emphasized, and few successful examples have been reported. The main challenge for blend systems is compatibility of two components. Herein, a series of (polydimethylsiloxane-based PU)-g-(poly (propylene glycol)-based PU) ((PDMS-PU)-g-(PPG-PU)) graft copolymers with different graft chain lengths and hard segment contents (HSC) were synthesized and utilized as compatibilizers of PDMS-PU/PPG-PU blends. The influence of the structure of compatibilizers on the morphology of blends was investigated, and the compatibilization mechanism was proposed. With the solubilization, the phase structure of blends transforms from “droplet-in-matrix” morphologies to co-continuous ones, and the average size of PPG-PU dispersed phase decreases from 3.5 ± 0.45 μm to 230 ± 60 nm. This is the first time that thermoplastic PDMS-PU/PPG-PU blends with co-continuous structures have been successfully prepared. The properties of blends exhibit synergistic effects. For example, they show high tensile strength of PPG-PU in mechanical properties and unique properties of PDMS in dynamic mechanical properties, weather resistance, water resistance and biocompatibility. In addition, strain sensors were fabricated by introducing carbon nanotubes (CNTs) into the blends, which demonstrated remarkable sensing capability for diverse human body motions.

A scalable and aging-resistant film for radiative cooling

Passive radiative cooling could reduce energy consumption by reflecting sunlight and radiating heat into outer space at long wave infrared. However, it is challenging that development of environmentally stable radiation-cooled materials that are easy to manufacture and have good weathering resistance. In this work, we developed a scalable radiative-cooling porous film of doped BaSO4 cellulose acetate(BSCA) with good environmental stability. The reflectivity was 0.94 with BSCA film to scatter most of the sun’s rays efficiently and an emissivity of 0.98 to radiate heat rapidly. The maximum temperature different with BSCA film were reduced by 8 ℃ less than the porous cellulose acetate (PCA) film, 13 ℃ than the commercial white paint (CWP) film. Meanwhile, in the switch boxes testing, the surface maximum temperature of the switch box coated with BSCA film were reduced by 9.9 ℃ than the switch box coated with CWP film, which were reduced by 14.7 ℃ than the original switch box. The simulated cooling power of BSCA film was 140.23 W·m−2. The BSCA film shows good optical performance and cooling performance after 3 months of outdoor aging test. The BSCA film is aging-resistant, easy to prepare and convenient for scalable production.

Preliminary study of scandium enrichment in Çaldağ-Manisa lateritic Ni-Co Deposit, Western Anatolia

Scandium is one of the most valuable critical metals, with high demand in applications ranging from biomedical research to electronics. Lateritic Ni-Co deposits are considered prime targets for scandium (Sc) exploration because Sc can be concentrated during weathering through residual and secondary enrichment, reaching up to 100 ppm and making it a potential by-product. This study investigates the distribution of Sc in the unweathered parent rocks and various laterite zones within two distinct pits of the Çaldağ lateritic Ni-Co deposit in Western Anatolia. In the Hematite pit, the serpentinite protolith shows an average Sc content of 10.3 ppm, with significant enrichment in the middle-upper limonite zone, reaching up to ~66 ppm. Although this represents a sixfold increase compared to the serpentinite protolith, the maximum Sc concentrations (53.6–65.7 ppm) are relatively low compared to other nickel laterites with by-product Sc potential (~100 ppm). This lower concentration is attributed to the initial low Sc content of the serpentinized peridotite protolith and post-lateritization tectonic activity. Conversely, the South pit exhibits higher initial Sc content in the protolith (~13 ppm) but lower average Sc content (~6.4 ppm) in the limonite zone, likely due to post-lateritization dissolution of Sc-hosting minerals by alteration and secondary weathering processes within the highly deformed pit. The findings suggest that while the Çaldağ deposit exhibits Sc concentrations up to ~66 ppm in the limonite zones, the potential for Sc as a by-product alongside Ni production is limited. Further detailed mineralogical and geochemical investigations are recommended to gain a deeper understanding of the mechanisms of Sc distribution in the Çaldağ deposit and other lateritic deposits in Türkiye.

Composite Superhydrophobic Coating with Transparency and Thermal Insulation for Glass Curtain Walls.

In this paper, the preparation of a transparent superhydrophobic composite coating with a thermal insulation function using antimony-doped tin oxide (ATO) nanoparticles is proposed, which has advantages of being mass-producible and low-cost. In short, nanosilica and ATO are used as raw materials for constructing rough structures, and superhydrophobic coatings are obtained by mixing and adding binders after modification of each, which are then applied to the surface of various substrates by spraying to obtain a transparent superhydrophobic coating with a heat-insulating function. The specific role of each nanoparticle is discussed through comparative experiments that illustrate the mechanism by which the two particles construct rough structures. The coating achieves unique thermal insulation properties while possessing excellent superhydrophobicity (WCA of ∼163° and WSA of ∼3°) and high light transmission (∼70%). Heat-shielding experiments have demonstrated that the composite coating effectively reduces the room temperature by approximately 19% for the same irradiation time. The coating achieves a balanced improvement in visible transmittance, thermal insulation, and superhydrophobicity. In addition, the coating's self-cleaning properties, mechanical properties, chemical weathering resistance, high-temperature resistance, and anti-icing properties were verified through various experiments.

Unveiling the release mechanism of potentially toxic elements from Pb/Zn smelter contaminated soils under the coupled effects of freeze–thaw and acidification: Insights from mineralogical analysis

Most Pb/Zn smelter contaminated sites in China are often encountered natural phenomenon known as freeze–thaw (F–T) cycles and acid rain. However, the coupled effects of F–T cycles and acidification on the release behavior of potentially toxic elements (PTEs) from soils remains unclear. A mechanistic study on PTEs release from soils was conducted by revealing the physicochemical weathering characteristics of minerals under F–T cycles combined with acidification. The results from F–T test indicated that among F–T parameters, F–T frequency were the more important factors influencing PTEs release, with the corresponding contribution ranges of 21.20–94.40 %. As pH decreased, the leaching concentrations of As, Cd, Cu, Mn, Pb and Zn did not increase under the same F–T frequency. As F–T frequency increased, the leaching concentrations of these studied PTEs also did not increase under the same pH condition. Microstructure characteristics revealed that the soils were a complex system with multi–mineral aggregates, which had experienced complex physicochemical weathering after F–T combined with acidification treatment. Combined with geochemical modeling results, PTEs release was found to be mainly influenced by the microstructure damage and proton corrosion of minerals, while little affected by their precipitation and dissolution. The mutual coupling relationships of mineral weathering and PTEs release were conducive to the better understanding of the migration behavior of PTEs in contaminated sites under complex environment scenarios. The present study results would provide theoretical instruction and technical support for the longevity evaluation of multi–metal stabilization remediation.

Comprehending Spatial Distribution and Controlling Mechanisms of Groundwater in Topical Coastal Aquifers of Southern China Based on Hydrochemical Evaluations

Groundwater quality and availability in coastal aquifers have become a serious concern in recent times due to increased abstraction for domestic, agricultural and industrial purposes. (1) Background: Zhuhai city is selected as a representative coastal aquifer in Southern China to comprehensively evaluate the hydrochemical characteristics, spatial distribution and controlling mechanisms of groundwater. (2) Methods: A detailed study utilizing statistical analyses, a Piper diagram, Gibbs plots, and ion ratios was conducted on 114 surface water samples and 211 groundwater samples. (3) Results: The findings indicate that the pH of most groundwater is from 6.06 to 6.52, indicating a weakly acidic environment. The pH of surface water ranges from 5.35 to 9.86, with most values being weakly alkaline. The acidity in the groundwater may be related to the acidic atmospheric precipitation, an acidic unsaturated zone, oxidation of sulphide minerals and tidal action. The groundwater chemical types are predominantly mixed, followed by Ca-Mg-HCO3 type. Surface water samples are predominantly Na-Cl-SO4 type. The NO3− concentration in groundwater is relatively high, with a mean value of 17.46 mg/L. The NO2− and NH4+ concentrations in groundwater are relatively low, with mean values of 0.46 mg/L and 7.58 mg/L. (4) Conclusions: The spatial distribution of the principal chemical constituents in the groundwater is related to the landform. The chemical characteristics of groundwater in the study area are mainly controlled by the weathering and dissolution of silicate and sulfate minerals, evaporation, seawater mixing and cation exchange. Nitrate in clastic fissure groundwater, granite fissure groundwater and unconfined pore groundwater primarily originates from atmospheric precipitation, agricultural activities of slope farmland and forest land. Nitrate in confined pore groundwater and karst groundwater primarily originates from domestic sewage and mariculture wastewater. Our findings elucidate the processes characterizing the hydrogeology and surface water interactions in Zhuhai City’s coastal system, which are relevant to other catchments with similar geological characteristics.

Improving Atmospheric Temperature and Relative Humidity Profiles Retrieval Based on Ground-Based Multichannel Microwave Radiometer and Millimeter-Wave Cloud Radar

Obtaining temperature and humidity profiles with high vertical resolution is essential for describing and predicting atmospheric motion, and, in particular, for understanding the evolution of medium- and small-scale weather processes, making short-range and near-term weather forecasting, and implementing weather modifications (artificial rainfall, artificial rain elimination, etc.). Ground-based microwave radiometers can acquire vertical tropospheric atmospheric data with high temporal and spatial resolution. However, the accuracy of temperature and relative humidity retrieval is still not as accurate as that of radiosonde data, especially in cloudy conditions. Therefore, improving the observation and retrieval accuracy is a major challenge in current research. The focus of this study was to further improve the accuracy of atmospheric temperature and humidity profile retrieval and investigate the specific effects of cloud information (cloud-base height and cloud thickness) on temperature and humidity profile retrieval. The observation data from the ground-based multichannel microwave radiometer (GMR) and the millimeter-wave cloud radar (MWCR) were incorporated into the retrieval process of the atmospheric temperature and relative humidity profiles. The retrieval was performed using the backpropagation neural network (BPNN). The retrieval results were quantified using the mean absolute error (MAE) and root mean square error (RMSE). The statistical results showed that the temperature profiles were less affected by the cloud information compared with the relative humidity profiles. Cloud thickness was the main factor affecting the retrieval of relative humidity profiles, and the retrieval with cloud information was the best retrieval method. Compared with the retrieval profiles without cloud information, the MAE and RMSE values of most of the altitude layers were reduced to different degrees after adding cloud information, and the relative humidity (RH) errors of some altitude layers were reduced by approximately 50%. The maximum reduction in the RMSE and MAE values for the retrieval of temperature profiles with cloud information was about 1.0 °C around 7.75 km, and the maximum reduction in RMSE and MAE values for the relative humidity profiles was about 10%, which was obtained around 2 km.

Enhancement of soil ecological remediation using a hydrogel material constructed by freeze–thaw driving force

Composite polymer materials as soil improvers are developed to enhance soil cohesion and aggregate stability. However, the improved soil still struggles to overcome the reduction in strength caused by day-to-day freeze–thaw (FT) cycle in the plateau area with large temperature difference. In this study, the natural power of FT cycle was used to drive the crosslinking of poly (vinyl alcohol) (PVA) and sodium alginate (SA) to form the interpenetrating networks of PVA-SA hydrogel. Then, this hydrogel was applied to stabilize the soil. The characterizations by FTIR, TGA, SEM and XRD indicated that the PVA-SA hydrogel had a porous, multi-channel and multi-chamber structure. Under the action of FT driving force, a series of studies including physical, chemical, water retention, direct shear, permeability, and aggregate stability were carried out on the soil with hydrogel applied. Compared to the control group, the data indicated that the cohesion of soil is significantly improved to 80 kPa. And the saturated hydraulic conductivity of the soil was reduced to 1/45 of the pre-modification rate, which had a positive impact on the water retention of the soil. What’s more, the results revealed that the PVA-SA hydrogel had effects on the aggregate stability, the submerged soil with added PVA-SA hydrogel still had no sign of disintegration and its mass percentage was greater than 99 % after 70 days. In a word, this composite material can effectively improve the cohesion and aggregate stability of the soil with the help of natural driving forces, which is potential to be used as remediation material for the plant layer in ecological restoration process.

Multivariate approach to assess groundwater resources in the multilayer system of Iullemmeden basin in Dosso Region, Southwestern Niger

The Iullemmeden basin groundwater resources were assessed in the Dosso Region for the groundwater management. Classical and multivariate tools of hydrogeochemistry were thus used to stand out main factors impacting the groundwater mineralization. The multilayer system indicates the occurrence of acidic to basic fresh groundwaters but with an excessive content in some places. Good to excellent drinking groundwaters are largely represented in the system. The categorization of groundwater patterns evolves from (i) mixed types namely Ca/Mg-HCO3, Ca/Mg-Cl, Na-Cl/SO4, Ca-Cl/SO4 and Ca/Mg-Cl/SO4 for the Ct3 particularly; (ii) to chloride types such as NaCl, CaCl and MgCl mostly for Ct1 and Ct2; (iii) and the bicarbonate types precisely Na-HCO3, Ca-HCO3, Mg-HCO3 for Ch. The weathering of silicate minerals and dissolution (carbonate and salts) are the major processes in the multilayer system. The increase of EC and salts (halite and gypsum) in Ct2 could come from the relics of ancient seawater during the last regression. In a lesser extent, fertilizers from agricultural and livestock farming also contribute to the mineralization in the study area. The groundwater assessment of the Iullemmeden sedimentary basin in the Dosso Region stands out the main factors and processes characterizing each aquifer of this system, able to useful for a better groundwater resource management.

Miocene magmatism in Northern Tunisia and its geodynamic implications

The Nefza igneous rocks in Northern Tunisia belong to the Miocene magmatic belt extending from Northern Tunisia to Morocco and consist mainly of Serravallian–Tortonian granodiorite and rhyodacite (~ 14–8 Ma) and Messinian basalts (~ 8–6 Ma). Differences in geochemical composition between units have been interpreted to be the result of geodynamic processes in the upper mantle below the Western Mediterranean area, but their implications for Northern Tunisia are unclear due to limited data. In this contribution, we present an updated geodynamic model for Northern Tunisia based on new petrographic and whole-rock geochemical results from the Nefza magmatic suite from outcrop and OB45 drill core samples. Petrographic observations show that rhyodacites display a microlithic texture with quartz, plagioclase, K-feldspar, biotite, and glass, whilst granodiorite contains plagioclase, quartz and exhibits fine-grained texture with a 2–3 mm crystal size. The Nefza magmatic rocks are overprinted by multiple weathering and alteration processes with loss of ignition (LOI) ranging between 0.88 and more than 5 wt%. The linear relationships between mobile elements (Ca, Na, P, K, Mg, Si), large-ion lithophile elements (LILE), and LOI suggest element mobilisation during alteration. Major and trace element compositions show the Nefza magmatic rocks plot in the rhyolite, dacite, and trachydacite fields for felsic rocks and plot in the basalt and trachybasalt fields for mafic rocks. Granodiorite and rhyodacite rocks exhibit negative Eu anomalies and a LILE enrichment (Rb, Ba, Pb) relative to high-field-strength elements (HFSE: Nb, Ta, Hf, Zr, REE). Mafic rocks enriched in LILE show geochemical characteristics between calc-alkaline and alkaline trends. Comparison with nearby regions suggests that the generation of calc-alkaline magmas resulted from the partial melting of the lithospheric mantle due to slab break-off or tearing in Eastern Algeria. The upward flow of asthenospheric material through the widening tear in the sinking slab leads to partial melting of the mantle and shallowing of the lithosphere–asthenosphere boundary, ultimately leading to the formation of alkaline magma. The Nefza geochemical variations underscore Mediterranean upper mantle heterogeneity, offering crucial insights into Mediterranean geodynamics. More studies are needed to constrain mantle dynamics and the region’s complex geological history.

Research Progress on Effects of Freeze-Thaw Action on Wind Erosion and Dust Resistance of Microbial Cured Bare Soil

Research Progress on Effects of Freeze-Thaw Action on Wind Erosion and Dust Resistance of Microbial Cured Bare Soil

Characterization, formation mechanism, and human health risk assessment of fluoride in shallow groundwater of Suzhou city, East China

ABSTRACT Groundwater is a vital water source for human consumption and irrigation. Understanding its fluoride content and health implications is crucial for water resource management. This study investigated the quaternary aquifer in Suzhou, China, collecting and analyzing 49 groundwater samples. Thermodynamic simulation, multivariate statistical analysis, and health risk assessment models were employed to determine fluoride concentration characteristics, hydrochemical controlling mechanisms, and noncarcinogenic risks. Results revealed an average fluoride concentration of 0.89 mg/L, with 26.5% of samples exceeding the Grade III groundwater quality standard. High-fluoride groundwater (>1 mg/L) exhibited spatial heterogeneity and was predominantly of the Na-Mg-HCO3 hydrochemical type. Multivariate analysis and thermodynamics simulations indicated that water–rock interactions (e.g., silicate mineral weathering and fluorite dissolution) governed groundwater hydrochemistry. Fluoride primarily originated from fluoride-bearing mineral dissolution, while negative cation exchange and precipitation of calcite and dolomite enhanced fluoride enrichment. pH had minimal impact on fluoride concentrations under weakly alkaline conditions. Health risk assessment suggested that fluoride in shallow groundwater posed a higher noncarcinogenic risk to children than adults via ingestion. These findings provide valuable insights for regional groundwater resource management.

Exploring the synergy of enhanced weathering and Bacillus subtilis: A promising strategy for sustainable agriculture.

Climate change is one of the most urgent environmental challenges that humanity faces. In addition to the reduction of greenhouse gas emissions, safe and robust carbon dioxide removal (CDR) technologies that capture atmospheric CO2 and ensure long-term sequestration are required. Among CDR technologies, enhanced silicate weathering (ESW) has been suggested as a promising option. While ESW has been demonstrated to depend strongly on pH, water, and temperature, recent studies suggest that biota may accelerate mineral weathering rates. Bacillus subtilis is a plant growth-promoting rhizobacterium that can facilitate weathering to obtain mineral nutrients. It is a promising agricultural biofertilizer, as it helps plants acquire nutrients and protects them from environmental stresses. Given that croplands are optimal implementation fields for ESW, any synergy between ESW and B. subtilis can hold great potential for further practice. B. subtilis was reported to enhance weathering under laboratory conditions, but there is a lack of data for soil applications. In a soil-mesocosm experiment, we examined the effect of B. subtilis on basalt weathering. B. subtilis-basalt interaction stimulated basalt weathering and increased soil extractable Fe. The combined application displayed higher CDR potential compared to basalt-only application (3.7 vs. 2.3 tons CO2 ha-1) taking solid and liquid cation pools into account. However, the cumulative CO2 efflux decreased by approximately 2 tons CO2 ha-1 with basalt-only treatment, while the combined application did not affect the CO2 efflux. We found limited mobilization of cations to the liquid phase as most were retained in the soil. Additionally, we found substantial mobilization of basalt-originated Mg, Fe, and Al to oxide- and organic-bound soil fractions. We, therefore, conclude that basalt addition showed relatively low inorganic CDR potential but a high capacity for SOM stabilization. The outcomes indicated the importance of weathering rate-GHG emission integration and the high potential of SOM stabilization in ESW studies.

GIS-Based Mapping of the Water Quality and Geochemical Assessment of the Ionic Behavior in the Groundwater Aquifers of Middle Ganga Basin, Patna, India

The study implemented Geographic Information System (GIS) techniques and multivariate hydrogeochemical analysis to evaluate the spatial-temporal and seasonal variation in the groundwater quality of Patna, India. For this purpose, sixty groundwater samples were collected and analyzed for major anions and cations during the pre-monsoon, monsoon, and post-monsoon seasons of 2019-2020. The physicochemical parameters such as pH, EC (Electrical Conductivity), TDS (Total Dissolved Solids), TH (Total Hardness), Ca2+, Mg2+, Na+, K+, HCO3-, Cl-, SO42- were considered to evaluate the water quality index. The result revealed degradation in groundwater quality from pre-monsoon (49.21) to post-monsoon (74.48). EC, TDS, TH, Mg2+, Na+, Ca2+, K+, and HCO3- ions were found accountable for high WQI values at various sampling sites during different seasons. Spatial maps showed that 45 % of the sampling stations exhibited poor quality in all three seasons, where the eastern part of the studied region was revealed to be the most affected area. The application of multivariate statistical methods and hydrogeochemical investigation has clearly defined the dominant role of the weathering process, and reverse ion exchange mechanism in controlling the aquifer’s ionic chemistry. Moreover, poor seepage system, and waste leachate from the surface have been found as the main cause of high levels of Na+, K+, and Cl- in the eastern part of Patna.

The Global Distribution of Water and Hydroxyl on the Moon as Seen by the Moon Mineralogy Mapper (M3)

The Moon Mineralogy Mapper (M3) on the Chandrayaan-1 spacecraft provided nearly global 0.5–3 μm imaging-spectroscopy data at 140 m pixel–1 in 85 spectral bands. Targeted locations were imaged at 70 m pixel–1 and higher spectral resolution. These data enable a detailed look at the mineralogy, hydroxyl, and water signatures exposed on the lunar surface. We find evidence for multiple processes, including probable solar wind implantation, excavation of hydroxyl-poor and water-poor material in cratering events, excavation of hydroxyl and water-rich materials from depth and global trends with rock type and latitude. Some water-rich areas display sharp boundaries with water-poor rocks but have a diffuse halo of hydroxyl surrounding the water-rich rocks indicating a weathering process of destruction of water, probably due to a regolith gardening process. Mapping for specific mineralogy shows evidence for absorptions near 2.2 μm, probably associated with smectites, and near 1.9 μm due to water. Lunar swirls are confirmed to be OH-poor, but we also find evidence that swirls are water-poor based on a weak 1.9 μm water band. Some swirls show enhanced pyroxene absorption. “Diurnal” signatures are found with stable minerals. Pyroxene is shown to exhibit strong band depth changes with the diurnal cycle, which directly tracks the solar incidence angle and is consistent with changing composition and/or grain size with depth. Mapping of M3 data for the presence of iron oxides (e.g., hematite and goethite) is found to be a false signature in the M3 data due to scattered light in the instrument.

Surface weathering process of earthen heritage under dry-wet cycles: A case study of Suoyang City, China

Dry-wet cycle is a key factor in surface weathering of earthen heritage, which remains insufficiently explained. It involves the interaction of humidity, stress, and damage. Using the RFPA (realistic failure process analysis) numerical method, this study reproduced the processes of humidity diffusion, deformation, stress, and damage evolution under dry-wet cycles in the soil site of Suoyang City, China. The numerical results indicate that the drying phase following rainfall has the most significant deteriorative impact on the earthen heritage. The evaporation of surface moisture during this phase causes volume shrinkage, which in turn generates tensile stress and leads to the formation of numerous desiccation cracks. Desiccation cracks provide channels for moisture diffusion, which further exacerbates generation of the cracks, leading to a mutual promotion between the two phenomena. Furthermore, during the wetting phase, the model elements undergo hygroscopic expansion, resulting in a slight increase in strain and displacement. Previously formed cracks may exhibit temporary narrowing or closure, but will revert during the subsequent drying phase. Ultimately, the overall displacement increases with the number of dry-wet cycles. The findings provide a theoretical foundation for protection against surface weathering and other damage in earthen heritage in arid regions.