Environmental Earth Sciences最新文献

Groundwater serves an indispensable function in regions characterized by intensive agricultural activities, particularly within karst landscapes where the availability of surface water is markedly limited. In this research, an exemplar of a densely agricultural plain on Yungui Plateau is utilized to delve into the impact of agricultural activities on groundwater human health risk and water quality through detailed hydrogeochemical investigations. About 55.56% and 66.67% of groundwater samples are found to have NO₃⁻ and NH₄⁺ contents exceeding the permissible limits for drinking purpose, respectively. Groundwater presents a trend of gradual evolution from HCO₃-Ca type to Cl-Mg·Ca or Cl-Ca type along with increase of NO₃⁻ concentration. Water–rock interactions are the main natural factor that govern the groundwater hydrochemistry. Agricultural activities are the main causes of the enrichment of NO₃⁻ and salinity in groundwater. The potential non-carcinogenic risks for adult males, adult females, children and infants posed by toxic substances of NO₃⁻, Fe, Mn, As and F are in the range of 0.317–9.836, 0.335–10.402, 0.342–10.598, and 0.584–18.114, respectively, and the main spread way is oral pathway. The health risks are mainly attributed by the excessive NO₃⁻ and As, which should be concerned in agricultural practices. EWQI value of groundwater is between 22.1 and 317.7, and only 33.33% of samples are suitable for direct drinking. Measures such as raising public awareness and selecting groundwater with good quality as the water supply source should be adopted to provide technical support for reducing anthropogenic pollution of groundwater in agricultural plains and protecting the health of residents.

This study investigates the mineral and soil characteristics of stone coal mine in southern China, focusing on metal pollution, chemical fractions, and associated risks. The research highlights significant enrichment of vanadium (V) and cadmium (Cd) in the stone coal. V is predominantly found in aluminosilicate minerals (83.7%), while Cd is exclusively associated with sulfide minerals (100%). In comparison to contaminated site soil, the form of V in paddy soil may change due to alternating dry and wet farming conditions, resulting in an increased proportion of reducible and oxidizing states. Additionally, Cd is released through sulfide weathering and migrates to deeper soils via acidic weathering solutions, posing high biological toxicity and mobility. Principal Component Analysis indicates that metal accumulation in the mining area is closely linked to natural geological factors, mining activities, and agricultural practices. The Geo-Accumulation Index (I_geo) and high hazard quotients (HQ) demonstrate severe cadmium pollution in the NB mine area (I_geo = 4.75) and potential non-carcinogenic risks from V for children (HQ > 1). These findings are crucial for ecological restoration efforts, promoting sustainable agricultural practices, and enhancing public health in areas impacted by mining activities.

To solve the problems of surrounding rock large deformation and support difficulties caused by two strong dynamic pressure disturbances of working face mining in reused roadway, this study took the 33(4)18 reused roadway of the Shuangliu Coal Mine (China) as a case study. Physical similarity model experiments, numerical simulation, and theoretical analysis were used to comprehensively analyze the evolution law of field of surrounding rock stress and displacement. The distribution law of abutment pressure during upper working face mining was established, and the formula of advance abutment pressure during following working face mining was derived. The deformation and failure mechanism of reused roadways was revealed from the perspective of the influence of principal stress difference on the development form of the plastic zone, combined with the Mohr–Coulomb strength theory, and a surrounding rock control scheme with ACC as the main supporting component was proposed. The results show that repeated cyclic loading and unloading fail to form a closed stress path, resulting in irreversible structural damage, including tensile damage of shallow surrounding rock and shear damage of deep surrounding rock. Uncontrollable residual deformation of surrounding rock at post-peak strength occurs in the subsequent loading process. The proposed support scheme effectively controls the mutual slip of fractured rock mass in shallow surrounding rock and greatly improves the roadway stability. The results provide theoretical and practical support for the research and engineering application of roadway support in similar working conditions.

The risk mapping of flood-prone areas enables the visualization of disaster risks, which can serve as a basis for the development of disaster mitigation strategies. This study presents a new hybrid multi-criteria decision analysis method that combines geographic information systems in Hanchuan City, integrating multidisciplinary fields to develop a more systematic and accurate assessment method. We selected 19 factors to create models for hazard, sensitivity, vulnerability, and disaster prevention. For the first time, a vulnerability model considered the impacts of population, economy, housing, and crops to optimize the indicator system. This model calculated weights using the improved analytic hierarchy process based on the cloud model, combined the entropy weighting method and game theory, and applied ArcGIS 10.8 to generate a risk map. The model results were validated using historical disaster sites, with an accuracy of up to 92%. The results indicate that the annual waterlogging index in the hazard model, land use in the sensitivity model, population and GDP in the vulnerability model, and shelter capacity in the disaster prevention model had larger weights and were closely related to meteorological, hydrological, and emergency responses. Approximately 17.55% of the study area falls within the high-risk zone, while 35.10% classified as medium–high risk is concentrated in the east-central region of the Han River. This risk assessment will serve as a basis for urban emergency policies, helping similar urban areas realize sustainable development strategies.

The study aims to determine the source of NH₄⁺ ions in the mineral waters of the Hranice Karst. The study area is located in the eastern part of the Czech Republic, Europe. The area is known mainly for its carbon dioxide of deep origin; the gas was the factor that enabled the formation of hypogene karst, in the Palaeozoic limestones, as well as warm mineral waters. The limestones of the area are covered by Neogene (Miocene) sediments of variable thickness and lithology. Recurrent sampling was done at 36 sites. A total of 96 surface water samples, 65 borehole water samples and 96 karst water samples were assessed. Major anions, cations and the content of nitrogen and its forms were determined for all water samples. The soil types were characterised by a field pedological survey. The normalised difference vegetation index was calculated in QGIS and vegetation vitality was evaluated. Since places with remarkably low vegetation index were found to be linked to the occurrence of Miocene sandstones, they represent points of rather fast entry of rainwater into the ground. As the presence of carbon dioxide creates an anoxic setting underground, the entering nitrates are transformed into NH₄⁺ ions. This mechanism of transformation within the nitrogen cycle explains the presence of NH₄⁺ ions in areas with elevated CO₂.

Groundwater in the F'kirina plain of eastern Algeria plays a crucial role in human life and agriculture. The present study was conducted to analyze the hydrogeochemical characteristics of this plain's groundwater in a semi-arid region. Twenty samples were collected (in June 2022) and tested for ions, such as Na⁺, K⁺, Mg²⁺, Ca²⁺, NH₄⁺, Cl⁻, HCO₃⁻, NO₃⁻, NO₂⁻, SO₄²⁻, Br⁻, Sr²⁺ as well as temperature, pH, electrical conductivity (EC) and total dissolved solids (TDS). The results were analyzed using the XLSTAT software with Principal Component Analysis (PCA), Piper, and Gibbs diagram. Four hydrochemical facies were identified, reflecting the diverse processes influencing water chemistry in the study area, such as, chloride-calcium, sodium bicarbonate-calcium and sulfate–calcium, defining the sample characteristics. The study also assessed water quality using the Water Quality Index (WQI) based on WHO guidelines and found that 50% of wells exceeded the recommended limits for major elements. (PCA) identified geological and anthropogenic factors that influence water chemistry, with geological substrate and agricultural practices contributing to groundwater degradation in the area.

The novelty of this research lies in its integrated approach, combining multivariate statistical analysis, hydrogeochemical diagrams, and WQI to provide a comprehensive assessment of groundwater quality. This multidisciplinary methodology effectively identifies both natural geochemical processes and anthropogenic influences, offering innovative insights into how evaporation and water–rock interactions shape groundwater chemistry in a semi-arid context. The findings not only enhance understanding of groundwater dynamics in the F'kirina plain but also provide a practical framework for sustainable water resource management in similar arid and semi-arid regions.

Biological equilibrium has been disturbed by significant land use changes in recent years in the Eastern Ghats of India, which has worsened soil quality and compromised vital ecosystem services. To determine the effect of changes in land use on the balance of soil carbon, this study was carried out in Kolli hills, a portion of the Eastern Ghats that includes six distinct ecosystems: evergreen forest (EF), deciduous forest (DF), thorn forest (TF), agricultural system (AS), horticultural system (HS), and plantation system (PS). Soil from 40 sites each within six ecosystems at two depths were collected to give a total of 480 soil samples, and the samples were analyzed. The results showed that soil organic carbon, carbon stock, microbial biomass carbon, and microbial biomass nitrogen were more significant in EF > DF > TF and lower in AS. The observed carbon stocks in EF, DF, and TF were 179.96, 146.80 and 128.99 t ha⁻¹, respectively, at 15 cm and decreased at 30 cm. Among the carbon pools, the water-soluble, less labile, very labile, non-labile, labile, and particulate organic carbon were greater in EF and lower in AS. The EF had higher soil microbial biomass, carbon, nitrogen, and dehydrogenase enzyme activity levels than the DF and TF. Finally, it is determined that AS, HS, and PS must immediately implement carbon management measure to restore productivity and ecosystem function.

The impact of urbanization and economic growth on terrestrial carbon storage is a complex and multidimensional issue involving land use change, carbon cycle, ecosystem services, etc. Remote sensing technology plays an important role in this study because it can provide a large amount of spatial and temporal data to help monitor and evaluate these impacts. In this study, we used Geo AI to optimize the predictive capabilities of the InVEST model, improve the efficiency and accuracy of data processing, and provide more accurate data support for the InVEST model. The study found that: (1) the overall carbon sequestration across the YREB decreased, with a reduction of 0.35%, 0.85%, and 2.28% in the upper, middle and lower reaches respectively. Notably, the upper region witnessed an expanding trend of carbon sequestration loss, while the lower region has shown some degree of alleviation. (2) The coupling degree between urbanization and carbon sequestration in Shanghai is significantly lower compared to other regions. Additionally, regions with an increasing coupling degree between carbon sequestration and population have a population urbanization rate generally below 60%. Similarly, regions with relatively lower land coupling degree have a land urbanization rate below 11%. Furthermore, regions with lower industrial coupling degree have an industrial urbanization rate exceeding 92%. (3) Carbon sequestration and economic growth exhibit a decoupling trend, with the lower region having a lower decoupling degree compared to the middle and upper regions. However, the decoupling status in the middle and upper regions tends to deteriorate, while the lower region shows signs of improvement.

Compacted bentonite is part of the multi-barrier system of radioactive waste repositories. The assessment of the long-term performance of the barrier requires using reactive transport models. Here we present a multiphase flow and reactive transport benchmark for radioactive waste disposal. The numerical model deals with a 1D column of unsaturated bentonite through which water, dry air and ({hbox {CO}_{2{(g)}}}) may flow and with the following reactions; aqueous complexation, calcite and gypsum dissolution/precipitation, cation exchange and gas dissolution. INVERSE-FADES-CORE V2, (hbox {DuMu}^X), TOUGHREACT and iCP were benchmarked with 6 test cases of increasing complexity, starting with conservative tracer transport under variably unsaturated conditions and ending with water flow, gas diffusion, minerals and cation exchange. The solutions of all codes exhibit similar trends. Small discrepancies are found in conservative tracer transport due to differences in hydrodynamic dispersion. Computed ({hbox {CO}_{2{(g)}}}) pressures agree when a sufficiently refined grid is used. Small discrepancies in ({hbox {CO}_{2{(g)}}}) and pH are found near the no-flow boundary at early times which vanish later. Discrepancies are due differences in the formulations used for gas flow at nearly water-saturated conditions. Computed ({hbox {CO}_{2{(g)}}}) pressures show a fluctuation between (10^{-4}) and (10^{-3}) years which slows down the in-diffusion of ({hbox {CO}_{2{(g)}}}). This fluctuation is associated with chemical reactions involving ({hbox {CO}_{2}}). There are discrepancies in solute concentrations due to differences in the Debye–Hückel (DH) formulation. They are overcome when all codes use the same DH formulation. The results of this benchmark will contribute to increase the confidence on multiphase reactive transport models for radioactive waste disposal.

The Structure-from-Motion-Multi-View Stereo (SfM-MVS) techniques with high-resolution photographs acquired with unmanned aerial vehicles (UAVs), were applied to investigate rock slopes with distinct structural styles. Photos were captured with varying flight plan settings, including manual and automatic overflights with fixed and unfixed gimbal pitch angle. The 3D point clouds were generated with the Agisoft Metashape software and segmented in the CloudCompare software (plugin FACETS) to identify the discontinuity systems. A comparison between digital and compass-based measurements was conducted to validate the accuracy of the 3D digital outcrop models. The study area comprises two vertical cut slopes situated in southeastern Brazil: one in a basalt quarry in Iracemápolis municipality, São Paulo State, and another at km 6 of the ES-482 highway, Espírito Santo State, excavated in poorly fractured banded gneiss. The results revealed that the automatic overflight produced a more accurate 3D digital outcrop model compared to the manual overflight, owing to the regularity of the photo grid. Additionally, the automatic overflight with an unfixed gimbal pitch angle configuration provided the most accurate 3D digital outcrop model. SfM-MVS techniques with drone photos provide better coverage of the rock slope compared to the traditional scanline method. However, the latter remains crucial in structural surveys because the data facilitate the segmentation and interpretation of the digital outcrop models, allowing for the differentiation of discontinuity types and thereby enhancing structural mapping accuracy.