Soil moisture is a vital parameter for a variety of applications including hydrological modelling and climate change studies, particularly in permafrost regions where freeze-thaw processes and complex terrain pose significant monitoring challenges. This study evaluates the accuracy of seven surface soil moisture (SSM) products (SMOS-IC, ESA CCI, AMSR2 LPRM, SMAP-L3, SMAP-L4, ERA5-Land, GLDAS-Noah) and three root-zone soil moisture (RZSM) products (SMAP-L4, ERA5-Land, GLDAS-Noah) using in situ observations from 19 stations in the permafrost region of the Heihe River Basin, China, from 2012 to 2020. Focusing on the thawing season (July-October), the analysis employs statistical metrics including Pearson correlation coefficient (R), unbiased root mean square error (ubRMSE), bias, and slope. Results indicate that SMAP-L3 and SMAP-L4 exhibit the highest SSM accuracy (R = 0.24 and 0.23, respectively) with low ubRMSE (0.037-0.038), while ERA5-Land shows the best RZSM correlation (R = 0.43) but may indicate the presence of systematic biases, nonlinear responses, or limitations in dynamic range, among other issues (slope = 0.01). Environmental factors such as precipitation, land surface temperature, and normalised difference vegetation index significantly influence accuracy. Spatial variability and scale mismatches highlight the need for improved land surface models and data assimilation. This study provides critical insights for selecting and refining soil moisture products to enhance hydrological and climate research in permafrost regions.

An anomalous warm weather event in the Antarctic McMurdo Dry Valleys on 18 March 2022 created an opportunity to characterize soil biota communities most sensitive to freeze-thaw stress. This event caused unseasonal melt within Taylor Valley, activating stream water and microbial mats around Canada Stream. Liquid water availability in this polar desert is a driver of soil biota distribution and activity. Because climate change impacts hydrological regimes, we aimed to determine the effect on soil communities. We sampled soils identified from this event that experienced thaw, nearby hyper-arid areas, and wetted areas that did not experience thaw to compare soil bacterial and invertebrate communities. Areas that exhibited evidence of freeze-thaw supported the highest live and dead nematode counts and were composed of soil taxa from hyper-arid landscapes and wetted areas. They received water inputs from snowpacks, hyporheic water, or glacial melt, contributing to community differences associated with organic matter and salinity gradients. Inundated soils had higher organic matter and lower conductivity (p < .02) and hosted the most diverse microbial and invertebrate communities on average. Our findings suggest that as liquid water becomes more available under predicted climate change, soil communities adapted to the hyper-arid landscape will shift toward diverse, wetted soil communities.

The morphology of sheep wool applied as organic fertilizer biodegraded in the soil was examined. The investigations were conducted in natural conditions for unwashed waste wool, which was rejected during sorting and then chopped into short segments and wool pellets. Different types of wool were mixed with soil and buried in experimental plots. The wool samples were periodically taken and analyzed for one year using Scanning Electron Microscopy (SEM) and Energy-dispersive X-ray Spectroscopy (EDS). During examinations, the changes in the fibers' morphology were observed. It was stated that cut wool and pellet are mechanically damaged, which significantly accelerates wool biodegradation and quickly destroys the whole fiber structure. On the contrary, for undamaged fibers biodegradation occurs slowly, layer by layer, in a predictable sequence. This finding has practical implications for the use of wool as an organic fertilizer, suggesting that the method of preparation can influence its biodegradation rate. (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)(SEM)(sic)(sic)(sic)(sic)(sic)X(sic)(sic)(sic)(sic)(EDS)(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)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).

BackgroundAccelerated glacial retreat driven by climate change is rapidly reshaping alpine and polar environments, exposing deglaciated terrains that serve as critical sites for microbial colonization and early ecosystem development. These newly exposed substrates provide a unique setting for studying primary microbial succession, the onset of soil formation, and the initiation of biogeochemical cycles, particularly carbon cycling. Microbial communities, including bacteria, archaea, fungi, algae, and viruses, play pivotal roles in regulating elemental fluxes and establishing foundational ecosystem processes in these nascent landscapes.ResultsRecent studies highlight substantial shifts in microbial community structure and function across different glacial forefields and cryospheric habitats. Microbial assemblages display pronounced spatial heterogeneity shaped by physicochemical gradients and successional age. Functional analyses reveal diverse metabolic pathways involved in carbon fixation, organic matter transformation, and long-term carbon storage. Additionally, viral populations emerge as influential regulators of microbial metabolism and potential archives of past environmental conditions. The assembly of these communities is influenced by a combination of abiotic factors, dispersal mechanisms, and local adaptation, with cascading effects on carbon fluxes and nutrient dynamics.ConclusionsMicrobial processes in deglaciated environments are central to early biogeochemical transformations and represent key drivers of carbon sequestration in retreating glacial landscapes. Understanding the ecological roles, functional diversity, and climate sensitivity of these microbial communities is essential for projecting biogeochemical and climate system feedbacks in the context of ongoing glacial loss. Integrating microbial ecology into Earth system models will enhance predictions of carbon dynamics and inform conservation and climate mitigation strategies in polar and alpine regions.

Glacier shrinkage, a notable consequence of climate change, is expected to intensify, particularly in high-elevation areas. While plant diversity and soil microbial communities have been studied, research on soil organic matter (SOM) and soil protein function dynamics in glacier forefields is limited. This limited understanding, especially regarding the link between microbial protein functions and biogeochemical functions, hampers our knowledge of soil-ecosystem processes along chronosequences. This study aims to elucidate the mechanistic relationships among soil bacterial protein functions, SOM decomposition, and environmental factors such as plant density and soil pH to advance understanding of the processes driving ecosystem succession in glacier forefields over time. Proteomic analysis showed that as ecosystems matured, the dominant protein functions transition from primarily managing cellular and physiological processes (biological controllers) to orchestrating broader ecological processes (ecosystem regulators) and increasingly include proteins involved in the degradation and utilization of OM. This shift was driven by plant density and pH, leading to increased ecosystem complexity and stability. Our confirmatory path analysis findings indicate that plant density is the main driver of soil process evolution, with plant colonization directly affecting pH, which in turn influenced nutrient metabolizing protein abundance, and SOM decomposition rate. Nutrient availability was primarily influenced by plant density, nutrient metabolizing proteins, and SOM decomposition, with SOM decomposition increasing with site age. These results underscore the critical role of plant colonization and pH in guiding soil ecosystem trajectories, revealing complex mechanisms and emphasizing the need for ongoing research to understand long-term ecosystem resilience and carbon sequestration.

Global warming results in more field soil suffering freeze-thaw cycles (FTCs). The environmental risk of microplastics-recognized as a global emerging contaminant-in soils undergoing FTCs remains unclear. In this study, the combined effects of FTCs and poly(butylene adipate-co-terephthalate) (PBAT) microplastics on microbial degradation of atrazine in Mollisols were investigated. Freeze-thaw cycles, rather than microplastics, significantly inhibited the biodegradation of atrazine in soil, with average inhibition ratios of 33.69% and 4.99% for FTCs and microplastics, respectively. Thawing temperature was the main factor driving the changes in soil microbial community structures and the degradation of atrazine. The degradable microplastics with an amendment level of 0.2% had different and limited effects on the dissipation of atrazine under different modes of FTCs. Among the four modes, microplastics only showed a trend toward promoting atrazine degradation under high-frequency and high-thawing-temperature FTCs. Across all modes, microplastics altered microbial interactions and ecological niches that included affecting specific bacterial abundance, module keystone species, microbial network complexity, and functional genes in soil. There's no synergistic effect between microplastics and FTCs on the degradation of atrazine in soil within a short-term period. This study provides critical insights into the ecological effects of the new biodegradable mulch film-derived microplastics in soil under FTCs.

To investigate the coupled time effects of root reinforcement and wet-dry deterioration in herbaceous plant-loess composites, as well as their microscopic mechanisms, this study focused on alfalfa root-loess composites at different growth stages cultivated under controlled conditions. The research included measuring root morphological parameters, conducting wet-dry cycling tests, and performing triaxial compression tests and microscopic analyses (CT scanning and nuclear magnetic resonance) on both bare loess and root-loess composites under various wet-dry cycling conditions. By obtaining shear strength parameters and microstructural indices, the study analyzed the temporal evolution of the shear strength and microstructural characteristics of root-loess composites under wet-dry cycling. The findings indicated that the alfalfa root-loess composite effective cohesion was significantly higher than that of the plain soil in the same growth stage. The alfalfa root-loess composite effective cohesion increased during the growth stage in the same dry-wet cycles. The alfalfa root-loess composite effective cohesion in the same growth stage was negatively correlated with the number of dry-wet cycles. The fatigue damage of the soil's microstructure (pore coarsening, cement hydrolysis, and crack development) increased continuously with the number of dry-wet cycles. However, due to the difference in mechanical properties between roots and the soil, the root-soil composite prevented the deterioration of the soil matrix strength by the dry-wet cycles. As the herbaceous plants grow, the time effect observed in the shear strength of the root-soil composite under the action of dry-wet cycles is the result of the interaction and dynamic coordination between the soil-stabilizing function of the herbaceous plant roots and the deterioration caused by drywet cycles.

This study systematically investigated the pore structure response of kaolin and illite/smectite mixed-layer rich clay in a reconstituted state to one-dimensional (1D) compression by first performing oedometer tests on saturated clay slurries, followed by characterising their pore structure using multi-scale characterisation techniques, with the primary objective of advancing the current understanding of the microstructural mechanisms underlying the macroscopic deformation of such clays. Under 1D loading, the volume reduction observed at the macro level essentially represented the macroscopic manifestation of changes in inter-aggregate porosity at the pore scale. It was the inter-particle pores that were compressed, despite the interlayer pores remaining stable. Two distinct pore collapse mechanisms were identified: kaolin exhibited a progressive collapse of particular larger pore population in an ordered manner, whereas illite/smectite mixed-layer rich clay demonstrated overall compression of inter-aggregate pores. Accordingly, mathematical relationships between the porosity and compressibility parameters for these two soils were proposed, with the two exhibiting opposite trends arising from their distinct microstructural features. Approaching from the unique perspective of pore structure, quantitative analysis of pore orientation and morphology on the vertical and horizontal planes demonstrated some progressively increasing anisotropy during compression. These findings provide important insights into porescale mechanisms governing clay compression behaviour and enrich the limited microporosity database in soil mechanics.

Fragile fruits, which are prone to mechanical damage and microbial infection, necessitate protective materials that possess both cushioning and antimicrobial properties. In this study, we present a novel genipin-crosslinked chitosan/gelatin aerogel (CS/GEL/GNP) synthesized through direct mixing and free-drying techniques. The mechanical properties and cushioning capacities of the CS/GEL/GNP aerogel were thoroughly characterized, alongside an evaluation of its antimicrobial efficacy. The composite aerogel demonstrated remarkable compressibility and shape recovery characteristics. In a transportation simulation test, the aerogel effectively protected strawberries from mechanical damage. Furthermore, the composite aerogel exhibited enhanced antimicrobial activities against Escherichia coli, Staphylococcus aureus and Botrytis cinerea in vitro. The quality of strawberries was successfully maintained at ambient temperature when packaged with the CS/GEL/GNP. Notably, the aerogel could be completely degraded in the soil within 21 days and is nontoxic to cells. Consequently, the dual-functional CS/GEL/GNP aerogel presents a promising option for packaging materials aimed at protecting delicate fruits.

Evaluating petroleum contamination risk and implementing remedial measures in agricultural soil rely on indicators such as soil metal(loid)s and microbiome alterations. However, the response of these indicators to petroleum contamination remains under-investigated. The present study investigated the soil physicochemical features, metal(loid)s, microbial communities and networks, and phospholipid fatty acids (PLFAs) community structures in soil samples collected from long-(LC) and short-term (SC) petroleum-contaminated oil fields. The results showed that petroleum contamination increased the levels of soil total petroleum hydrocarbon, carbon, nitrogen, sulfur, phosphorus, calcium, copper, manganese, lead, and zinc, and decreased soil pH, microbial biomass, bacterial and fungal diversity. Petroleum led to a rise in the abundances of soil Proteobacteria, Ascomycota, Oleibacter, and Fusarium. Network analyses showed that the number of network links (Control vs. SC, LC = 1181 vs. 700, 1021), nodes (Control vs. SC, LC = 90 vs. 71, 83) and average degree (Control vs. SC, LC = 26.244 vs. 19.718, 24.602) recovered as the duration of contamination increased. Petroleum contamination also reduced the concentration of soil PLFAs, especially bacterial. These results demonstrate that brief exposure to high levels of petroleum contamination alters the physicochemical characteristics of the soil as well as the composition of soil metal(loid)s and microorganisms, leading to a less diverse soil microbial network that is more susceptible to damage. Future research should focus on the culturable microbiome of soil under petroleum contamination to provide a theoretical basis for further remediation. (c) 2025 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.