Environmental Earth Sciences最新文献

Global concern regarding microplastics (MPs) has increased due to their potential risks. The primary source of microplastic contamination in the ocean is often terrestrial transfer from nearby locations. This study evaluated microplastic pollution in the Terekhol and Sal estuaries, found near their mouths, during the monsoon season of 2022. The size, shape, and colour of the MPs were determined using stereomicroscope, while Fourier-transform infrared (FTIR) analysis was used for polymer identification. The average concentration of MPs in the Terekhol and Sal estuaries were 0.25 particles/L and 0.30 particles/L, respectively, with the highest concentrations detected in the 5 –1 mm size range in both estuaries. While fibres predominated in the Terekhol estuary and fragments were more common in the Sal estuary, white was the dominating colour in both estuaries. Polymer identification revealed the presence of polyethylene (PE), polypropylene (PP), and polyamide in both estuaries. The Pollution Load Index (PLI) values exceeded 1 indicated that both estuaries are contaminated with MPs. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) analysis of MPs from both estuaries indicated varying levels of surface degradation and also the presence of various elements (C, O, Fe, Si, Ru, Cu, Co, Zn, Al, K, Na and Cl) on the surface of these MPs. These findings suggest that river inflows and fishing-related activities are likely the primary contributors to pollution caused by MPs in these estuaries.

This study examines the interrelationship between land use, urban growth patterns, and the urban heat island effect in Istanbul, Turkey, utilising Landsat images spanning the period from 1990 to 2018. The land surface temperatures are derived from Landsat images, and the urban growth patterns are obtained using the Corine Land Cover and Global Human Settlement databases. Urban growth patterns are classified into four categories: high-rise high-density, high-rise low-density, low-rise high-density, and low-rise low-density. It is observed that the urban built-up areas in Istanbul have more than doubled during the study period, while the agricultural and forest areas have undergone a significant decrease. In consequence, there has been a notable increase in land surface temperatures (LST). The findings of the study indicate that artificial surfaces, particularly continuous urban fabric, industrial and commercial units, and airports, have exhibited the highest LST over time. A statistical analysis reveals a relationship between the growth pattern and surface temperature changes. The development patterns of high-rise low-density and low-rise low-density do not significantly contribute to the formation of urban heat islands. In contrast, high-rise high-density development and low-rise high-density development exert a pronounced influence on the formation of urban heat islands. Furthermore, a negative correlation was observed between vegetation coverage and LST, whereas a positive correlation was noted between building density and imperviousness and LST. The urban heat island effect in Istanbul, a major global metropolitan area with a population of approximately 16 million, is exhibiting a continuous increase due to the dynamics of urban growth. The findings of this study can inform the formulation of urban growth strategies for the forthcoming years, thereby facilitating thermal comfort.

Cold climates accelerate the weathering of building stones via freeze–thaw (FT) cycles. This situation causes natural stones to begin to lose their integrity and subsequently decreases their strength. This study was conducted to demonstrate the impact of FT cycles on the course of uniaxial compressive strength (UCS) on very large number of natural stone sample types. For this purpose, 46 sample groups were subjected to 4, 7, 10, 14, 20, 28, 35, 56, 70, and 84 FT cycles under laboratory conditions, and UCS values were determined at the end of cycles. Additionally, ultrasonic P-wave velocities (V_P) were measured in three directions on each fresh cubic sample, and the anisotropy coefficient (C_A) was calculated. The effect of anisotropy to the strength loss of natural stones due to FT cycles was evaluated by the C_A coefficients. Results suggested that the non-linear UCS loss, notably up to 35%, especially for the stones having greater than 5% open porosity (n). In addition, it has been revealed that sample groups with calculated C_A coefficients above 15% are more prone to deterioration due to FT cycles. The Frost Resistance Index (FRI), defined as the ratio of the UCS value obtained after a specific FT cycle to the UCS value obtained on the fresh sample, was calculated for all groups at the end of respective cycles. A generalized classification system consisted of “very high”, “high”, “moderate”, “low” and “very low” classes based on the FRI parameter for deteriorated building stones has been proposed for practice.

Drought is a significant natural disaster with adverse effects on both social and ecological systems. Unlike other natural disasters, drought develops slowly and gradually, complicating its early detection and often resulting in severe impacts on affected regions. Consequently, accurate and dependable drought monitoring is essential for devising effective mitigation strategies. Standardized drought indices are vital tools in drought monitoring, providing a means to quantify and characterize drought events. Most standardized drought indices utilize the Standardized Precipitation Index (SPI) method, which is valued for its simplicity and flexibility. However, this study contends that the SPI method lacks several critical elements, particularly in practice, such as determining the most suitable probability distribution for hydrometeorological variables. Therefore, this study proposes a novel methodology for calculating standardized drought indices and assesses its performance against conventional and nonparametric standardized indices, employing various methods capable of capturing complex dependencies. The novel methodology involves identifying the best-fit probability distributions for each data group through various goodness-of-fit tests. This approach ensures that each group is modeled optimally, considering the seasonal variations inherent to each group. The Seyhan River Basin has been chosen as a case study for the proposed methodology. The drought characteristics of the basin are analyzed using indices derived from the new methodology, the conventional SPI method, and the nonparametric method. Additionally, trend analyses were performed on the calculated indices to identify any directional changes in drought patterns within the Seyhan River Basin. The performance of the proposed methodology was evaluated by analyzing its relationship with nonparametric standardized indices and comparing it to the relationship between conventional standardized indices and nonparametric standardized indices. The results show that the newly proposed methodology outperforms the conventional SPI method across various dependence measures, suggesting it captures the underlying data structure more effectively than the SPI method.

Aquifer characterization is crucial, specifically in regions where it continuously depletes and deteriorates with time. This study deals with geophysical and hydrochemical borehole logging techniques to assess the lithology of the Lahore aquifer and its impact on groundwater chemistry. To execute this study, eight observatory wells were installed in the selected regions at 200 ft depth to run MGX-II logger. According to the results of the water samples collected from the boreholes the concentrations levels of majority of the physicochemical parameters are within allowable limits prescribed by the WHO except As, HCO₃ ^–, and TDS. Geochemical analysis indicate the existance of geogenic activities, resulting from the weathering of carbonate (calcite and dolomite) and silicate (quartz, feldspar, pyroxene, amphibole, mica, and olivine) minerals. The Gibbs plot and Pipper trilinear diagram revealed that Na⁺–HCO₃⁻, Ca²⁺–Na⁺–HCO₃⁻, and mixed Ca²⁺–Mg²⁺–HCO₃⁻ are the eminent soil and rock-weathering processes. The aquifer was efficiently delineated as unconsolidated sands, silt and clay particles based on the lithological logs and natural gamma-ray data showing a wide variation between 20.44 and 195.47 cps. The outcome of the multi-parameter probe revealed that the in situ measured temperature, thermal gradient, pressure, pH, and redox potential (Eh) varied between 12.1 and 22.5 °C, 0.004 –0.02 °C/ ft, 5.34–8.13 dbar, 6.7–8.7, and 112 to 232 DmV, indicating the anoxic condition in the Lahore aquifer respectively. This study successfully reveals the effectiveness of the combined use of advanced geophysical and hydrochemical borehole log measurements at the regional level.

The influence of intermediate principal stress (σ₂) on the strength of rocks varies greatly among different types of rocks under the true triaxial stress state, and few attentions have been paid to it. It is found that under conventional triaxial compression, rock strength exhibits nonlinear characteristics, while under true three-dimensional loading, σ₂ has a significant impact on the rock strength. Analyzing the experimental results of fourteen kinds of rocks revealed that the σ₂ effect was divided into two stages (strength promoting stage and strength weakening stage). Based on these concepts, a true triaxial strength criterion was then proposed. Finally, its accuracy and applicability were examined by comparing the predicted results with the experimental results. This criterion was also compared with the other three criteria (namely Mogi-Coulomb criterion, Drucker-Prager criterion and Chen-Chen criterion). Errors analysis shows that this proposed strength criterion is generally the best with low absolute and relative errors, followed by Mogi-Coulomb criterion, Chen-Chen criterion, and Drucker-Prager criterion. This criterion retains the advantage of the Hoek–Brown (H-B) criterion, as its parameters are selected from the traditional H-B criterion. The newly introduced parameters can be applied to judge the existence of strength weakening stage of intermediate principal stress effect and determine the critical interval of the two stages. This proposed strength criterion has certain reference value for the prediction of rock strength and the evaluation of engineering surrounding rock safety.

Landslide-generated waves pose significant risks. They can cause substantial economic losses and casualties. Accurate prediction of landslide-generated wave characteristics and potential consequences is critical for effective disaster management. In this study, a detailed simulation approach for landslide-generated waves using the multiphase smoothed particle hydrodynamics (MSPH) method has been developed, which can consider the soil–water interaction. Unlike traditional methods that treat landslide bodies as rigid blocks or discrete particles, the MSPH method accounts for the internal constitutive relationships and large deformations of the landslide mass. This method demonstrates superior performance in handling complex grid distortions, strong nonlinearities, and discontinuities in wave generation zones. After validating the model against experimental data, the MSPH method has been applied to simulate the Wangjiashan landslide. A total of 18 monitoring points were used to track the propagation of the landslide-generated wave. The simulation results show a maximum wave height of 5.73 m, which is close to those derived from alternative methods, thereby confirming the model’s accuracy. The simulation results not only enhance the understanding of landslide dynamics but also provide critical insights into wave behavior in reservoir environments, offering valuable guidance for disaster mitigation and risk management.

Enzyme induced carbonate precipitation (EICP) is an emerging sustainable technology in the field of geotechnical engineering. It involves the application of urease, a plant-based urease enzyme which mediates the precipitation of calcium carbonate (CaCO₃) via hydrolysis of urea. This results in biocementation and subsequent improvement of the strength of the soil. In purview of this developing bio-stabilization technique, Life cycle assessment (LCA) can be used as a promising tool for incorporating sustainability metrics to evaluate the environmental impacts related to EICP technique and assist in policy and decision making. In this present study, an attributional LCA is conducted to investigate and quantify the various environmental impacts associated with EICP concentrations as proposed by various researchers. The environmental impact indicators taken into consideration are global warming potential (GWP), eutrophication potential (EP), energy use potential (EUP) and freshwater ecotoxicity potential (FWP). The results revealed that chemical constituents of EICP i.e., urea (51.25–74.53%) and non-fat milk powder (52.82–87.11%) are the dominant contributors to GWP (max: 2146.95 kg CO₂ eq). Urea also contributes to EUP in the range between 69.58 and 92.6% (max: 14,279 MJ). However, NH₄Cl, the by-product (NH₄Cl) of EICP process, a water pollutant, is the major contributor to EP (max: 326.44 kg N eq) and FWP (max: 289.25 kg 1,4-DCB eq). This indicates that more focus should be bestowed on EP and FWP to better characterize and quantify the associated ecosystem response due to over-utilization of the chemicals, for any EICP stabilization technique. Thus, this analysis considers the aspect of sustainability inground modification technique, aiding the advancement of EICP research.

Graphical Abstract

This study presents a comparative analysis of horizontal and pipe drains in earth dams, focusing on optimizing seepage control and stability. Using the Kreireche dam in Algeria as a case study, we employed GeoSlope software (SEEP/W and SLOPE/W) to conduct numerical simulations across 20 different scenarios, varying drain configurations and hydraulic conditions. Results indicate that pipe drains significantly outperform horizontal drains in managing seepage and enhancing dam stability. Pipe drains with larger diameters (2 m) reduced pore pressure by 15–20% compared to horizontal drains, demonstrating superior seepage control. Optimal drain placement within the range of X/B = 0.2 to 0.4 led to maximum safety factors, highlighting the importance of drain positioning. Statistical analysis using RMS, MAE, and MSE metrics showed that pipe drains consistently provided more reliable seepage and exit gradient control compared to horizontal drains. Increasing pipe drain diameter from 1 m to 2 m improved discharge seepage prediction consistency, reducing normalized RMS and MAE by 18.5% and 17.3%, respectively. Pipe drains exhibited 64.2% lower normalized RMS values for exit gradient predictions compared to horizontal drains, indicating more effective erosion risk mitigation. This study provides important insights for enhancing drainage system design in earth dams, resulting in increased stability and long-term performance of these crucial water management structures.

This study quantifies groundwater recharge in the southern sections of the western Afar Rift margin and associated rift floor by employing multiple methods, including Water balance, Chloride Mass Balance, WetSpass modeling, and Baseflow separation controlled by radon measurement. The mean annual groundwater recharge rates obtained from the first two methods are 114.39 mm/year, and 92.37 mm/year respectively. The spatially distributed recharge determined from the WetSpass model shows the rift margin has higher values than the rift floor, and results in a mean recharge of 100.88 mm/year. The baseflow separation method calculates 136.7 mm/year and 17.86 mm/year at the outlets of the marginal grabens and inside the rift floor respectively. The higher value suggests additional groundwater flows from the adjacent plateau to the rift margin, driven by the extended columnar basalt and transverse structures. In contrast, the presence of highly faulted Dalha basalt along the Arcuate Accommodation Zones (AAZ) promotes groundwater seepage, leading to lower values in the rift floor. However, from the previous hydrochemical and isotope analysis, groundwater flows from the rift margin to the rift floor, due to the presence of transverse structures create preferential pathways that connect these areas. Hence, the rift floor can have moderate recharge. Therefore, the WetSpass model and Base-flow separation methods, supported by other techniques, provide reliable results in tectonically active areas like the Afar Triangle and arid to semi-arid regions. Last but not least, the study underscores the importance of using multiple techniques for accurate assessments of recharge rates and mechanisms in similar areas.