The Himalayan glacier valleys are encountering escalating environmental challenges. One of the contributing factors is thought to be the rising amounts of light-absorbing carbonaceous aerosols, particularly brown carbon (BrC) and black carbon (BC), that are reaching glacier valleys. The present study examines the optical and radiative characteristics of BC at Bhojbasa, near Gaumukh (similar to 3800amsl). Real-time in-situ BC data, optical characteristics, radiative forcing, heating rate, several meteorological parameters, and BC transport pathways to this high-altitude site are investigated. The daily mean concentration of equivalent black carbon (eBC) was 0.28 +/- 0.21 mu g/m(3) over the research period, and the eBC from fossil fuel (BCFF) is dominant with 78 % with a daily mean of 0.22 +/- 0.19 mu g/m(3)(,) and eBC from biomass burning (BCBB) is 22 % with a daily mean of 0.06 +/- 0.08 mu g/m(3). Meteorological data, Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) imaging, and backward air-mass trajectory analysis demonstrate the presence of BC particles and their plausible transit pathways from multiple source locations to the pristine Gangotri Glacier Valley. The estimated daily mean BC radiative forcing values are +6.71 +/- 1.80 W/m(2) in the atmosphere, +1.87 +/- 1.16 W/m(2) at the top of the atmosphere, and -4.84 +/- 1.01 W/m(2) at the surface with a corresponding atmospheric heating rate of 0.19 +/- 0.05 K/day. These findings highlight the critical role of ground-based measurements in monitoring the fluctuations of BC over such varied Himalayan terrain, as they offer important information on the localized trends and effects. Long-term measurements of glacier valleys are essential for a comprehensive evaluation of the impact of BC particles on Himalayan ecology and climate.

Black carbon (BC) is a major short-lived climate pollutant (SLCP) with significant climate and environmentalhealth impacts. This review synthesizes critical advancements in the identification of emerging anthropogenic BC sources, updates to global warming potential (GWP) and global temperature potential (GTP) metrics, technical progress in characterization techniques, improvements in global-regional monitoring networks, emission inventory, and impact assessment methods. Notably, gas flaring, shipping, and urban waste burning have slowly emerged as dominant emission sources, especially in Asia, Eastern Europe, and Arctic regions. The updated GWP over 100 years for BC is estimated at 342 CO2-eq, compared to 658 CO2-eq in IPCC AR5. Recent CMIP6-based Earth System Models (ESMs) have improved attribution of BC's microphysics, identifying a 22 % increase in radiative forcing (RF) over hotspots like East Asia and Sub-Saharan Africa. Despite progress, challenges persist in monitoring network inter-comparability, emission inventory uncertainty, and underrepresentation of BC processes in ESMs. Future efforts could benefit from the integration of satellite data, artificial intelligence (AI)assisted methods, and harmonized protocols to improve BC assessment. Targeted mitigation strategies could avert up to four million premature deaths globally by 2030, albeit at a 17 % additional cost. These findings highlight BC's pivotal roles in near-term climate and sustainability policy.

Against the backdrop of global warming, the increasing spatiotemporal variability in precipitation patterns has intensified the frequency and risk of dry-wet abrupt alternation (DWAA) events in semi-arid regions. This study investigates the Hailar River Basin in northern China (1980-2019) and develops the Soil Moisture Concentration Index (SMCI) using daily soil moisture (SM) data simulated by the VIC hydrological model. A high-resolution temporal framework is introduced to detect DWAA events and evaluate the impact of precipitation pattern variations on dry-wet transitions in the basin. The results indicate: (1) Annual precipitation in the basin has significantly increased (0.47 mm y(-1) in the south, P < 0.05), while precipitation intensity follows a gradient pattern, increasing in the upstream (3.65 mm d1 y1) and decreasing in the downstream (-2.34 mm y(-1)). Additionally, the number of dry days and short-duration, high-intensity precipitation events has risen; (2) Soil moisture (SM) data simulated by the VIC model effectively capture DWAA events, showing significantly higher | SMCI| values downstream than upstream (P < 0.05) and indicating more intense dry-wet transitions in the downstream region. Furthermore, 78 % of the area exhibits an increasing trend in |SMCI|(1980-2019), with dry-to-wet transition events occurring more frequently than wet-to-dry events. For instance, in 2013, the maximum coverage area reached 48 % in a single day; (3) The random forest model highlights the spatial heterogeneity of DWAA driving factors: upstream water yield is the dominant factor, whereas downstream variations are closely associated with precipitation intensity (R-2 = 0.76) and the frequency of heavy rainfall days. Permafrost degradation and land use changes further heighten hydrological sensitivity in the downstream region. This study offers a transferable methodological framework for understanding extreme hydrological events and reveals that the driving mechanisms of DWAA are spatially heterogeneous, shifting from being dominated by terrestrial factors in the headwaters to meteorological factors downstream-a finding with significant implications for water resource management in other large, heterogeneous semi-arid basins.

Light-absorbing carbonaceous aerosols, comprising black carbon (BC) and brown carbon (BrC), significantly influence air quality and radiative forcing. Unlike traditional approaches that use a fixed value of absorption & Aring;ngstrom exponent (AAE), this study investigated the absorption and optical properties of carbonaceous aerosols in Beijing for both local emission and regional transport events during a wintertime pollution event by using improved AAE results that employs wavelength-dependent AAE (WDA). By calculating the difference of BC AAE at different wavelengths using Mie theory and comparing the calculated results to actual measurements from an Aethalometer (AE31), a more accurate absorption coefficient of BrC can be derived. Through the analysis of air mass sources, local emission was found dominated the pollution events during this study, accounting for 81 % of all cases, while regional transport played a minor role. Carbonaceous aerosols exhibited a continuous increasing trend during midday, which may be attributed to the re-entrainment of nighttime-accumulated carbonaceous aerosols to the surface during the early planetary boundary layer (PBL) development phase, as the mixed layer rises, combined with the variation of PBL and anthropogenic activity. At night, variations in the PBL height, in addition to anthropogenic activities, effectively contributed to surface aerosol concentrations, leading to peak surface aerosol values during local pollution episodes. The diurnal variation of AAE470/880 exhibited a decreasing trend, with a total decrease of approximately 12 %. Furthermore, the BrC fraction showed a constant diurnal variation, suggesting that the declining AAE470/880 was primarily influenced by BC, possibly due to enhanced traffic contributions.

The long-term trend for aerosol optical properties and climate impact sensitivity in terms of radiative forcing efficiency were analyzed at a suburban station in Athens, Southeast Mediterranean, using an extensive dataset from 2008 to 2022. The study examined scattering (nsc) and absorption (nap) coefficients, scattering & Aring;ngstrom exponent (SAE), absorption & Aring;ngstrom exponent (AAE), single scattering albedo (SSA), asymmetry parameter (g), and radiative forcing efficiency (RFE). Seasonal variability was linked to meteorological conditions and human activities. Single Scattering Albedo (SSA) was lowest (0.86), and Radiative Forcing Efficiency (RFE) was highest (-61 W/m2) in winter, confirming enhanced contributions from traffic and biomass burning. Lower SAE values (1.5) in spring indicate a greater presence of coarse particles due to frequent Saharan dust events (SDEs). Daily patterns of nap and SSA reflect local emissions, with pronounced traffic-related peaks. Aerosol classification revealed that Black Carbon (BC) dominates the suburban aerosol (51 %), with mixed BrC-BC (16 %) peaking in winter and dust-pollution mixtures (13 %) increasing in spring. The presence of large particles mixed with BC (11 %) was more frequent in spring, further highlighting seasonal variability. Trend analysis showed statistically significant (ss) decreases in nsc (-0.611) and SSA (-0.003), alongside increases in nap (+0.027) and RFE (+0.270) at a 95 % confidence level, suggesting a shift toward more absorbing aerosols. The findings provide new insights and reveal a new aerosol regime, where a reduction in anthropogenic emissions is affecting the scattering rather than the absorbing aerosol component, while the impact from forest fires as a climate feedback mechanism has a significant effect in the Eastern Mediterranean. It is important for future studies and climate modelling to account for the regionally observed changes of the state of mixing of ambient aerosol leading to a shift in radiative forcing efficiency through the reduction in SSA. This is evident in the long term for the east Mediterranean region and must be accounted for in radiative forcing estimates and future climate projections.

Conventional materials necessitate a layer-by-layer rolling or tamping process for subgrade backfill projects, which hampers their utility in confined spaces and environments where compaction is challenging. To address this issue, a self-compacting poured solidified mucky soil was prepared. To assess the suitability of this innovative material for subgrade, a suite of performance including flowability, bleeding rate, setting time, unconfined compressive strength (UCS), and deformation modulus were employed as evaluation criteria. The workability and mechanical properties of poured solidified mucky soil were compared. The durability and solidification mechanism were investigated. The results demonstrate that the 28-day UCS of poured solidified mucky soil with 20% curing agent content reaches 2.54 MPa. The increase of organic matter content is not conducive to the solidification process. When the curing temperature is 20 degrees C, the 28-day UCS of the poured solidified mucky soil with curing agent content not less than 12% is greater than 0.8 MPa. The three-dimensional network structure formed with calcium silicate hydrate, calcium aluminate hydrate, and ettringite is the main source of strength formation. The recommended mud moisture content is not exceed 85%, the curing agent content is 16%, and the curing temperature should not be lower than 20 degrees C.

The reasonable value of good gradation characteristic parameters is key in designing and optimising soil-rock mixed high fill embankment materials. Firstly, the DJSZ-150 dynamic-static large-scale triaxial testing instrument was used for triaxial compression shear tests on compacted skeleton structure soil-rock mixture standard specimens. The changes in strength and deformation indicators under different gradation parameters and confining pressure were analysed. Then, based on the Janbu empirical formula, relationships between parameters K, n, and (sigma 1-sigma 3)ult and the coefficient of uniformity Cu and coefficient of curvature Cc were explored. Empirical fitting formulas for Duncan-Chang model constants a and b were proposed, establishing an improved Duncan-Chang model for soil-rock mixtures considering gradation characteristics and stress states. Finally, based on significant differences in particle spatial distribution caused by gradation changes, three generalised models of matrix-block stone motion from different particle aggregation forms were proposed. Results indicate the standard specimen's strength and deformation indicators exhibit significant gradation effects and stress-state correlations. The improved Duncan-Chang model effectively simulates the stress-strain relationship curve under different gradations and confining pressure, with its characteristics explainable based on the matrix block stone motion generalised model.

Most gravel roads leading to rural areas in Ghana have soft spot sections as a result of weak lateritic subgrade layers. This study presents a laboratory investigation on a typical weak lateritic subgrade soil reinforced with non-woven fibers. The objective was to investigate the strength characteristic of the soil reinforced with non-woven fibers. The California Bearing Ratio and Unconfined Compressive Strength tests were conducted by placing the fibers in single layer and also in multiple layers. The results showed an improved strength of the soil from a CBR value of 7%. The CBR recorded maximum values of 30% and 21% for coconut and palm fibers inclusion at a placement depth of H/5 from the compacted surface. Multiple fiber layer application at depths of H/5 & 2 h/5 yielded CBR values of 38% and 31% for coconut and palm fibers respectively. The Giroud and Noiray design method and the Indian Road Congress design method recorded reduction in the thickness of pavement of 56% to 63% for coconut fiber inclusion and 45% to 55% for palm fiber inclusion. Two-way statistical analysis of variance (ANOVA) showed significant effect of depth of fiber placement and fiber type on the geotechnical characteristics considered. (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic),CBR(sic)(sic)7%(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic)(sic)(sic)(sic)H/5(sic)(sic)(sic)(sic)(sic)(sic),CBR(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)30%(sic)21%. (sic)H/5(sic)2H/5(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)CBR(sic)(sic)(sic)(sic)38%(sic)31%. Giroud&Noiray(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)56%(sic)63%,(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)45%(sic)55%. (sic)(sic)(sic)(sic)(sic)(sic)(ANOVA)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).

Canopy reflectance (CR) models describe the transfer and interaction of radiation from the soil background to the canopy layer and play a vital role in the retrieval of biophysical variables. However, few efforts have focused on estimating soil background scattering operators, resulting in uncertainties in CR modelling, especially over sloping terrain. This study developed a canopy reflectance model for simulating CR over sloping terrain, which combines the general spectral vector (GSV) model, the PROSPECT model, and 4SAIL model coupled with topography (GSV-PROSAILT). The canopy reflectance simulated by GSV-PROSAILT was validated against two datasets: discrete anisotropic radiative transfer (DART) simulations and remote sensing observations. A comparison with DART simulations under various conditions revealed that the GSV-PROSAILT model captures terrain-induced CR distortion with high accuracy (red band: coefficient of determination $\lpar {\rm R 2} \rpar = 0.731$(R2)=0.731, root-mean-square error (RMSE) = 0.007; near infrared (NIR) band: $\rm R2 = 0.8319$R2=0.8319, RMSE = 0.0098). The results of remote sensing observation verification revealed that the GSV-PROSAILT model can be successfully used in CR modelling. These validations confirmed the performance of GSV-PROSAILT in soil and canopy reflectance modelling over sloping terrain, indicating that it can provide a potential tool for biophysical variable retrieval over mountainous areas.

Bedrock-soil layer slopes (BSLSs) are widely distributed in nature. The existence of the interface between bedrock and soil layer (IBSL) affects the failure modes of the BSLSs, and the seismic action makes the failure modes more complex. In order to accurately evaluate the safety and its corresponding main failure modes of BSLSs under seismic action, a system reliability method combined with the upper bound limit analysis method and Monte Carlo simulation (MCS) is proposed. Four types of failure modes and their corresponding factors of safety (Fs) were calculated by MATLAB program coding and validated with case in existing literature. The results show that overburden layer soil's strength, the IBSL's strength and geometric characteristic, and seismic action have significant effects on BSLSs' system reliability, failure modes and failure ranges. In addition, as the cohesion of the inclination angle of the IBSL and the horizontal seismic action increase, the failure range of the BSLS gradually approaches the IBSL, which means that the damage range becomes larger. However, with the increase of overburden layer soil's friction angle, IBSL's depth and strength, and vertical seismic actions, the failure range gradually approaches the surface of the BSLS, which means that the failure range becomes smaller.