Physics and Chemistry of the Earth最新文献

The green economy development (GED) has emerged as a paramount objective for urban progress in the 21st century, emphasizing the harmonious advancement across economic, social, and environmental domains. Yet, the impact of population urbanization, a pivotal driver of urban evolution, on GED remains ambiguous. Addressing this knowledge gap necessitates investigations at specific stages of rapid population urbanization in a certain country. In order to explore the relationship between them, this study focuses on China, a distinctive economic entity, utilizing the DEA-SBM model with unexpected outputs to assess its GED efficiency (GE). Additionally, employing the Tobit model, the study scrutinizes the impact of population urbanization on GE in China from 2000 to 2020. Mechanism analyses are further conducted to explore the key roles of environmental policies, population density, and R&D in fostering GE. Findings reveal: (1) a U-shaped relationship between population urbanization and GE; (2) significant enhancement of GE through green credit policy, alongside positive moderating the impact of environmental protection on GE; conversely, environmental assessment policy notably reduce GE, while positively moderating the impact of industrial structure rationalization on GE; (3) a U-shaped relationship between population urbanization and GE under low population density, with population urbanization significantly diminishing GE as population density reaches a critical level; (4) higher amount of R&D personnel corresponding to increased GE at equivalent population urbanization levels. Finally, several management strategies derived from these findings are offered, aiming to assist other developing nations in effectively improving their urban GE.

Groundwater ionic components evolution can simultaneously characterize the process of natural environment and anthropogenic activities on groundwater. In order to reveal the long-term evolution mechanism and influencing factors of urban groundwater in the context of rapid urbanization and industrialization. Studies carried out in Lanzhou, a region in Northwest China known for interconnection of anthropogenic activities and groundwater systems, sought to explore the mechanisms influencing the evolution of groundwater ionic components within the last 20 years. Hydrochemical analysis methods and integrated groundwater ion source analysis methods were utilized to isolate natural and anthropogenic factors in the evolution of groundwater ions, and subsequently combined with LULC to analyze the correlation between the type and intensity of land changes on groundwater ion components. The results show that, the ionic composition of groundwater was dominated by ion exchange and mineral weathering, river recharge, industrial activities, urban activities, and agricultural activities in 26%, 10%, 23%, 25%, and 16% of the sample sites respectively in 2002. However, in 2022, the proportion of sites dominated by these five categories is 20%, 18%, 12%, 40%, and 10%, respectively. Further combining the yearly trends in LULC, it is concluded that the decrease of cultivated land area and the significant increase of urban construction land in Lanzhou are closely related to the groundwater evolution process in Lanzhou in the past 20 years. Today's agricultural activities no longer dominate the ionic fraction of groundwater in Lanzhou, but increased population density and urban sewage discharge due to rapid and intensive urbanization are the main factors influencing the ionic fraction of groundwater.

Coal, traditionally utilised solely for combustion, is now being investigated for its potential as an adsorbent in purifying drinking water by eliminating hazardous metal ions. Limited research exists regarding its effectiveness in reducing organic dye levels. Presented here are the outcomes of an extensive investigation into various carbon samples' efficacy as adsorbents for wastewater color removal. Samples of coal sourced from Western Coalfield Limited (WCL) were meticulously processed and characterized, encompassing run-of-mine coal and acid-leached coal. A comprehensive array of techniques, including scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX), powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy, was employed for coal characterization. Proximate analysis and gross calorific value (GCV) were employed to assess coal's physical attributes. The adsorption behavior of methylene blue (MB) and crystal violet (CV) on coal was scrutinized, varying factors such as contact time, pH, initial MB and CV concentrations, and adsorbent doses. Optimal adsorption parameters for MB were determined as pH 2, initial concentration of 1 ppm, 0.2 g adsorbent dose, and 60 min contact time. For CV, optimal conditions were pH 8, initial concentration of 6 ppm, 0.4 g adsorbent dose, and 45 min contact time. MB adsorption kinetics favored the pseudo-second-order reaction model, with Freundlich isotherms providing a better fit than Langmuir isotherms. Conversely, CV adsorption kinetics favored the pseudo-second-order reaction model, with Langmuir isotherms exhibiting a superior fit compared to Freundlich isotherms.

To study the significant deformation and distortion issues in certain sections of the Qinyu tunnel extremely fragmented surrounding rock under identical conditions, six tunnel sections with the same depth of burial and lithology were selected for on-site monitoring of stress. The experimental data were then used to explore the impact of gradation on the mechanical characteristics of the extremely fragmented surrounding rock tunnels. The results indicate that the tunnel experiences larger stresses at the crown and smaller stresses at the side walls and invert, showing the influence of gradation on the stress behavior of extremely fractured surrounding rock. A dual-fractal structure model was employed to quantitatively describe the gradation of the surrounding rock, yielding fitting coefficients above 0.9. The model demonstrated good applicability for extremely fractured rock with significant particle size differences. Additionally, the relationship between fractal model parameters and the maximum rock pressure at various tunnel sections was discussed, revealing an exponential correlation between the absolute difference in fractal dimensions of coarse and fine particles and the maximum rock pressure. To further understand the factors and the influence of gradation on tunnel rock pressure, indoor model tests were conducted using six different gradations. The experimental results once again confirmed the importance of gradation on the stress behavior of highly fragmented rock tunnels and validated the functional relationship between the absolute difference in fractal dimensions and rock pressure. The results can provide guidance for the design of tunnels with extremely fractured surrounding rocks in the future.

Agricultural activities and rapid urbanization have significantly impacted groundwater quality, especially in semi-arid and arid regions. This study comprehensively evaluated the quality of phreatic and confined groundwater in the Yinchuan area, China, using long-term monitoring data from 1991 to 2018. Geospatial analysis model was employed to explore the spatiotemporal evolution of groundwater hydrochemistry. The effects of land use changes on groundwater quality were assessed using correlation analysis and a multiple linear regression model (MLR). The findings indicate significant temporal variations in groundwater quality, with phreatic water consistently exhibiting high salinity and hardness. The groundwater quality for phreatic water was frequently more polluted than confined water. From 1991 to 2018, the hydrochemical composition of phreatic water evolved from HCO₃-Mg and HCO₃·SO₄-Mg to more complex forms such as HCO₃·SO₄·Cl-Mg and HCO₃·Cl-Mg. In contrast, confined water predominantly maintained its HCO₃-Mg type and HCO₃·Cl-Na (Na·Mg) type. Urban land had rapidly expanded in the past three decades, increasing by 318.75% compared to 1991. The water body and urban area diminished the quality of phreatic water. High salt water in lakes and drainage ditches, combined with poor runoff conditions and intensive evaporation, caused the increase of TDS, Cl⁻, SO₄²⁻, Mn, TH, NO₃⁻, F⁻, and Fe in phreatic water. NO₃⁻, NH₄⁺, and F⁻ in phreatic water could be impacted by human and industrial activity in urban areas. This study provides valuable insights for local decision-makers to effectively manage groundwater resources and solve issues of groundwater scarcity and water quality problems in arid and semi-arid locations.

The pressing environmental concerns associated with fossil fuels have propelled renewable energy sources, particularly solar and wind energy, into a more prominent position. This article aims to explore an optimal configuration and conduct a technical and economic analysis of a hybrid solar-wind energy system tailored for electrifying Laayoune city. This system, equipped with hydrogen tank and batteries as storage devices, aims to meet the annual energy requirements of residential areas estimated at 310.87 GWh/year. In addition to addressing energy needs, the study tackles significant challenges such as reducing dependence on traditional energy sources, curbing greenhouse gas emissions, and bolstering energy security in the region. Utilizing HOMER Pro software, the research evaluates various combinations of renewable resources, including solar and wind, alongside storage solutions such as batteries, fuel cells, and hydrogen storage, to find the most viable solution in terms of electricity generation, cost, and environmental impact. The findings highlight a hybrid configuration comprising solar, wind, battery, grid, and converter components as the most cost-effective approach for Laayoune's renewable energy system. This integrated system not only yields an energy cost of 0.0477 $/kWh and a net present cost (NPC) of 336 M$ but also generates 627.69 GWh/year of energy. Furthermore, it achieves a 100% renewable energy ratio while completely eliminating CO₂ emissions.

The lack of observed data for the hydrological modelling of catchments across borders has hindered the management of transboundary water resources. This study investigated the implications of different degrees of hybridization of observed rainfall data using ERA5-Land reanalysis precipitation data in simulating streamflow in the Ruvubu River catchment across the Burundi-Tanzania border. The hydrological model of the Ruvubu River catchment was set up and iteratively updated using 0%–100% hybrid rainfall data, parameterized, simulated, and then evaluated against observed streamflow data at the catchment outlet. The findings show that the performance of the hydrological model decreased as the degree of rainfall data hybridization increased. However, model parameters satisfactorily compensated for input uncertainty when the model had hybrid rainfall data not exceeding 15% hybridization. Subsequently, errors in the simulated flow were also minimal. This implies that the simulated flow from the model when it has hybrid rainfall data not exceeding 15% hybridization can represent the simulated flow when it has 0% hybrid rainfall data. These findings show the need to develop thresholds of rainfall data hybridization for different global precipitation datasets in data-scarce transboundary river catchments.