Seismic moment tensors (MTs) in anisotropic media are more complex than those in isotropic media: while shear faulting produces pure double-couple MTs in isotropy, additional non-double-couple (NDC) components may arise in anisotropic materials. This effect is often neglected, leading to errors in MT inversion and misinterpretation of fracture mechanisms. In this paper, we investigate MTs of acoustic emissions generated during uniaxial loading of four granite rock samples. Although the samples were initially isotropic, they developed stress-induced anisotropy during loading. The anisotropy parameters were determined by acoustic scanning at various loading stages. A comparison of source parameters inverted using isotropic and anisotropic velocity models reveals minor differences in the orientations of the MT principal axes but significant differences in the NDC components. These results highlight the importance of accounting for rock anisotropy when accurately determining the fracture mechanisms of acoustic emissions in laboratory loading experiments.
IntroductionCashew (Anacardium occidentale) is one of the most economically and socially important perennial crops in the Brazilian semiarid region, supporting rural livelihoods while also representing a native species adapted to tropical drylands. Understanding how climate change may alter the environmental suitability of native species is critical for conservation planning and sustainable land use in dryland ecosystems.MethodsHere, we modeled the current and future potential distribution of Anacardium occidentale (cashew tree) across the Caatinga biome using MaxEnt (v.3.4.4) and bioclimatic predictors derived from two CMIP6 Earth System Models (EC-Earth3-Veg and MIROC6) under the SSP2-4.5 and SSP5-8.5 emission scenarios for the baseline period and future projections (2050 and 2070). Occurrence records were compiled from GBIF, SpeciesLink, and Embrapa databases and refined through ecological filtering and pedoclimatic zoning.ResultsThe current model showed high predictive performance (AUC ≈ 0.88), with approximately 25% of the biome classified as highly suitable (≥ 0.5), mainly concentrated in the northern Caatinga. Suitability patterns were primarily driven by precipitation seasonality, annual rainfall, elevation (altitude), and vegetation cover, indicating strong dependence on water availability and habitat structure. Future projections revealed substantial contractions of suitable areas, particularly under SSP5-8.5, with losses ranging from 68% (EC-Earth3-Veg) to 76% (MIROC6). Both climate models consistently indicated that increasing temperatures and reduced seasonal precipitation will intensify aridification, leading to a spatial retreat of the species niche toward coastal and sub-humid zones—areas that correspond to the historical origin and current climatic refugia of the species.DiscussionThese results demonstrate the high vulnerability of Anacardium occidentale to ongoing climate change and highlight the importance of conserving coastal and sub-humid microrefugia, as well as implementing climate-adaptive management strategies to support rural livelihoods and extractive systems dependent on cashew production in the Brazilian semi-arid region.
In island reef areas, the reinforcement of reclaimed coral sand foundations is challenged by uneven soil layer distribution and well-developed weak interlayers, while a bearing capacity evaluation system is still lacking. Additionally, the effectiveness of conventional reinforcement methods remain limited. To address these problems, laboratory soil tests and cyclic triaxial dynamic tests were conducted in this study based on an actual reclamation project in island reef areas. The test results were used to systematically analyze the physical and dynamic characteristics of coral sand. Meanwhile, four groups of comparative field vibro-compaction tests were conducted to investigate the influence of compaction point spacing, compaction method, and backfill particle size on the foundation reinforcement effect and identify the most effective construction parameters among the tested schemes. Moreover, empirical relationships among the dynamic penetration index, bearing capacity, and deformation modulus were established based on in situ test data to quantitatively evaluate the reinforcement effect. The test results demonstrated that the liquefaction behavior of coral sand was primarily governed by the drainage conditions. Under undrained cyclic triaxial conditions with a cyclic stress ratio of 0.2, the saturated coral sand specimens exhibited a sharp increase in dynamic strain and loss of stiffness after approximately 65 vibration cycles, indicating that the liquefaction behavior of coral sand is governed primarily by the drainage condition and providing the mechanistic basis for the “moderate-liquefaction” control of field vibration. The combination of a 3.5 m equilateral triangular layout, centroid densification, and coarse-grained backfill exhibited the most effective reinforcement effect among the field tesed schemes, significantly reducing the thickness of weak interlayers and improving foundation uniformity. In addition, the developed empirical formulas could accurately quantify the foundation reinforcement effect, providing reliable technical support and a theoretical reference for similar marine coral sand foundation reinforcement projects.
The production of biochar from rice-husk biomass has shown significant potential to counter climate change and waste management issues. The current study assesses changes in elemental, structural and thermal characteristics of biochar produced at 380 °C, 400 °C, and 420 °C at a residence time of 2 h. The study also calculates the CO2eq that is stored in biochar post-pyrolysis. The methodology adopted includes biochar production through pyrolysis, phase analysis, elemental analysis and CO2eq calculations. Phase analysis revealed destruction of the cellulosic phase and development of amorphous silica following pyrolysis. CHNS analysis showed increasing carbon concentration together with decreasing H/C and O/C atomic ratios, indicating enhanced aromatic condensation and increasing carbon recalcitrance during thermal treatment. Proximate analysis demonstrated substantial devolatilization, reduction in moisture and volatile matter, and enrichment of stabilized carbonaceous fractions. Biochar yield decreased from 60.108 g at 380 °C to 40.153 g at 420 °C because of increasing thermal decomposition and volatilization losses. The calculated retained CO2eq values ranged from 93.127 g for BC380 to 67.846 g for BC420, indicating that lower pyrolysis temperatures retained larger quantities of biomass-derived carbon despite relatively lower thermal maturity. However, the higher carbon concentration at elevated temperature did not result in greater total carbon retention because biochar yield decreased substantially with temperature. BC380 therefore retained the greatest absolute quantity of carbon despite having a lower carbon concentration than BC420. The study highlights the importance of optimizing pyrolysis conditions to maximize both carbon retention efficiency and carbon stability for sustainable biochar-mediated carbon sequestration applications.
Urban surface thermal anomalies are associated with land-cover characteristics and their surrounding environmental contexts. However, how environmental indicators relate to thermal anomalies under different land-cover contexts remains insufficiently understood. This study develops a LULC-specific and explainable framework to investigate how environmental indicators are associated with relative thermal anomalies under different land-cover contexts in Shanghai using Landsat observations from 2000, 2010, 2020, and 2024. Land surface temperature (LST), NDVI, NDBI, NDWI, and four LULC categories were derived and aggregated to 300 m × 300 m grid cells. LST was standardized separately for each observation date to derive a continuous thermal anomaly (TA) indicator. XGBoost with random and spatial block cross-validation was applied to examine the relationships between environmental indicators and TA, while SHAP analysis was used to interpret variable contributions and LULC-specific response patterns. The results reveal distinct thermal anomaly characteristics among LULC types. Built-up areas consistently showed positive TA values, whereas water bodies exhibited stable negative TA patterns. Vegetation areas generally showed lower TA values but retained internal thermal heterogeneity. Spatial block cross-validation resulted in slightly lower performance than random validation, indicating the importance of considering spatial dependence in thermal anomaly modelling. SHAP analysis identified NDBI as the predictor with the largest SHAP-based contribution to model predictions, followed by NDWI and NDVI, with distinct SHAP response patterns observed across LULC categories. These findings highlight that urban thermal conditions should be interpreted by considering both environmental indicators and land-cover background. The proposed framework provides a LULC-specific approach for interpreting relative thermal patterns and supporting preliminary urban heat adaptation assessment.
