Search Results (1,805)

Groundwater level (GWL) variations in the arid regions of Northwest China are driven by both natural processes and human activities. Identifying causal links between hydrological variables is fundamental to understanding groundwater evolution and conducting dynamic simulations. This study integrates the Mann–Kendall test, Seasonal-Trend decomposition using Loess, and the Peter and Clark Momentum-threshold and Momentary Conditional Independence (PCMCI) causal inference to analyze GWL variation characteristics and causal response processes across seven sub-basins in the Tarim Basin using multi-source remote sensing data. Results show an overall decline in GWL, primarily in the north-central part of the basin, with the Kaidu–Konqi River Basin reaching a maximum rate of 0.51 m/year. The trend components reveal localized depletion alongside broad stability, while seasonal components exhibit three types of temporal shifts in fluctuations. A mismatch exists between the prevalence of environmental influences and their causal strength. Daytime land surface temperature (LST_D), surface runoff (RO), and evapotranspiration (ET) show the highest detection frequencies, yet volumetric soil water in layers 2 (SWVL₂) and RO exhibit the largest ranges in strength and drive variations at specific sites. Response times are asymmetric. Negative effects from ET on GWL transmit quickly, while positive recovery is slow. Conversely, positive recharge from volumetric soil water in layer 1 (SWVL₁) is faster than its negative lag. At the basin scale, surface processes recharge GWL while mediating indirect influences from other variables. Climate and agricultural irrigation act as direct sinks. Depending on local conditions, three regional patterns emerge: direct climate-driven depletion, obstructed shallow water retention, and indirect compensation from agricultural water use. Causal networks indicate that RO and SWVL₁ have the highest centrality and dominate water output, whereas SWVL₂ acts as a passive receiver. Pathways from the surface to GWL are also asymmetric. The most frequent path involves step-by-step infiltration along RO → ET → SWVL₁ → SWVL₂ → GWL. In contrast, the paths with the highest cumulative strength are shorter and faster, specifically RO → ET → GWL and RO → SWVL₁ → GWL. The identified pathways and lag parameters provide a direct basis for groundwater dynamic modeling and water resource management in the basin. Full article

Wildfires are key drivers of Mediterranean forest dynamics, yet post-fire recovery and carbon cycling in coastal dune systems remain poorly understood, particularly under invasive species pressure. This study quantified how microtopography and dominant woody species shape vegetation recovery, carbon stocks, and soil CO₂ efflux in a Pinus pinaster plantation burned in 2017 in coastal Portugal, during the fifth post-fire hydrological year (2021–2022). Vegetation composition, aboveground biomass, litter, soil organic matter and total organic carbon were measured across dune crests and slacks, and soil respiration was repeatedly assessed under native—Halimium halimifolium—and exotic invasive—Acacia longifolia—woody species using a closed-chamber system. Woody cover was higher on crests, whereas slacks supported greater herbaceous cover and stronger increases in soil organic matter, with litter dominating biomass and carbon pools in all microsites. A. longifolia showed marked demographic expansion and higher soil respiration than the native shrub, while mixed-effects models revealed non-linear, interacting effects of soil moisture and temperature on CO₂ efflux. Overall, post-fire recovery and carbon dynamics were spatially heterogeneous and increasingly controlled by invasion, underscoring the need for microsite-specific restoration and early invasive control to safeguard carbon sequestration and native forest resilience in Mediterranean coastal dunes. Full article

While valorisation pathways are increasingly promoted as sustainable solutions, their ability to genuinely minimise environmental harm and contribute to long-term material circularity remains uneven. This study systematically identifies and maps existing valorisation routes across the EU and UK, with particular attention to their environmental performance and economic viability through a material value retention lens. A literature review highlights a spectrum of practices—from soil amendment and composting to bioenergy recovery and bio-based construction materials—each offering different sustainability benefits but varying significantly in their capacity to preserve material quality and function. To address the absence of robust comparative approaches, this paper introduces a novel evaluative framework centred on intrinsic material value retention, a key principle in sustainable and circular material systems. Building on established scholarship, the framework provides a structured means of comparing valorisation options based on how effectively they conserve material properties, particularly in terms of the material’s structural and functional values, and enable high-value reuse. Supported by a dedicated classification tool and a set of guiding questions refined through expert interviews, the framework complements existing environmental assessment methods by foregrounding material circularity. In doing so, it supports more integrated, holistic decision-making for the development of a resilient and sustainable circular bioeconomy. This research is intended for academic audiences and may also be of relevance to industry practitioners. Full article

The complexity of physicochemical properties in iron ore tailings has led to extensive and varied study avenues. Moreover, changes in these features resulting from source discrepancies have complicated the identification of consistent patterns in study findings, thereby hindering the standardization and advancement of resource exploitation technologies. This paper provides a comprehensive analysis of the utilization pathways for iron tailings. It identifies the mainstream recovery processes for rare earth minerals, a relatively less-researched direction. It also describes research progress on the use of iron tailings for the preparation of fertilizers and soil conditioners, as well as their application as cementitious materials or aggregates in building materials and mine backfilling engineering. It incorporates various activation methods for the preparation of cementitious materials from iron tailings into a unified comparative framework and quantifies the key performance indicators of different activation pathways through a summary table. It also summarizes studies on the ecological reclamation of tailings ponds based on bioremediation techniques. The essential physicochemical properties of iron deposits are meticulously analyzed, and this is followed by a specialized overview of the principal treatment techniques, critical performance indicators, and their foundational mechanisms. The current application of various technical approaches is examined to identify key problems, and future development opportunities are outlined. Full article

Subalpine grasslands represent highly sensitive ecosystems that are increasingly exposed to climate extremes, yet their long-term disturbance dynamics remain poorly documented. This study investigates climate-driven dieback of subalpine grasslands in Central Europe using a harmonized, multi-decadal satellite time series. We analyzed Landsat (TM, ETM+, OLI, OLI-2) and Sentinel-2 imagery spanning 1984–2024 to detect changes in grassland condition, supported by field-based validation, climatic indices, and geomorphological analysis. Several spectral indices related to non-photosynthetic vegetation were evaluated, with the Normalized Burn Ratio (NBR) providing the best discrimination of dead grassland. In spatially grouped cross-validation, NBR achieved very high accuracy for dead versus non-dead grassland, with AUC = 0.9996, precision = 1.00, recall = 0.82, and F1-score = 0.90 for Sentinel-2, and AUC = 0.9982, precision = 1.00, recall = 0.62, and F1-score = 0.76 for Landsat 9. Retrospective mapping revealed four dieback events since 2000: two short-term episodes with rapid within-season recovery (2000, 2003) and two long-term events characterized by persistent degradation and slow regeneration (2012, late 2018–2019). The largest short-term event, in 2003, affected 42.19 ha of total dieback and 96.95 ha including partially damaged or regenerating grassland. Dieback extent was negatively associated with water balance deficit, strongest for SPEI-12 (ρ = −0.548, p = 0.002), while winter frost under shallow-soil conditions likely contributed to long-term damage in 2012. Geomorphological analysis indicated that elevation, terrain curvature, and, to a lesser extent, wind exposure are the primary controls on dieback susceptibility, highlighting the importance of fine-scale environmental controls. Our results demonstrate the value of long-term, multi-sensor satellite observations for detecting and interpreting climate-driven disturbances in subalpine grasslands and provide a transferable framework to support monitoring and conservation of mountain ecosystems under ongoing climate change. Full article

To address yttrium (Y) contamination from ion adsorption mining, this study developed a combined microbial phytoremediation strategy for dual objectives: ensuring crop safety in Lactuca sativa and enhancing Y recovery by Solanum nigrum. Two specific microbial consortia were constructed from rare earth tailings isolates: inoculant I (bacterial: Enterobacter sp., Serratia sp., Bacillus sp.) applied to L. sativa, and inoculant II (fungal: Penicillium sp., Aspergillus sp., Talaromyces sp.) applied to S. nigrum. Inoculant I increased L. sativa biomass by 26% while reducing Y content in roots and rhizosphere soil solution by 47% and 56%, respectively, potentially through down-regulation of amino acid metabolites. Inoculant II increased Y content in the S. nigrum rhizosphere soil solution by 89%, linked to up-regulation of organic acids and coumarin derivatives. Both consortia reduced plant stress markers and enhanced soil enzyme activities. These findings demonstrate that specialized microbial consortia can differentially regulate Y behavior in the rhizosphere—immobilizing it in a crop for food safety, while enhancing its bioavailability for a hyperaccumulator—offering a targeted strategy for managing rare earth element-contaminated agricultural soils. Full article

Livestock manure resources are abundant in the upper Yellow River basin on the eastern Tibetan Plateau, where rapeseed (Brassica napus L.) is grown under cold, short-season alpine conditions. To identify a suitable organic fertilizer substitution proportion, a two-year randomized complete block field experiment was conducted on Chestnut soil (Kastanozem) to compare mineral fertilization with 25%, 50%, 75%, and 100% replacement of mineral N by an organic fertilizer produced from composted cattle and sheep manure under equal total N, P, and K inputs. Grain yield was highest at 50% substitution, increasing by about 14% relative to mineral fertilization (p < 0.05), whereas 100% substitution slightly reduced yield. Increasing manure inputs enlarged soil organic carbon and total nutrient pools, but these increases were not accompanied by proportional increases in plant-available nutrients. Compared with mineral fertilization, 50% substitution increased available N, P, and K by about 18%, 34%, and 10%, respectively, and also increased the proportions of total N, P, and K present in available forms. Activities of the measured extracellular enzymes were generally 12–72% higher under 50% substitution than under mineral fertilization. A piecewise structural equation model indicated that yield improvement was associated mainly with greater nutrient uptake and recovery efficiency. Overall, moderate substitution best balanced nutrient accumulation, nutrient availability, efficiency, and productivity under the tested alpine conditions. Full article

Vegetation restoration is critical for ecosystem recovery in abandoned mining areas, yet how restoration age affects soil multifunctionality (SMF) and the underlying microbial regulatory mechanisms remains poorly understood. The space-for-time substitution method was employed in this study. Along a revegetation chronosequence (Restoration 1 year (R1), Restoration 10 year (R10), Restoration 30 year (R30), Restoration 45 year (R45)) in copper mine wasteland in Tongling, China, the dynamics of soil functions, SMF, and microbial communities were quantified, with the key factors influencing soil functions and the most important predictors of SMF subsequently identified. The results showed that the soil moisture regulation function recovered relatively slowly, whereas nutrient cycling functions and SMF were generally enhanced with advancing revegetation. Specifically, these functions all reached their maximum values at R30 (0.39, 0.45, and 0.28, respectively), followed by declines at R45 (−0.74, −0.09, and −0.20, respectively). Furthermore, the soil microbial communities exhibited successional characteristics of increased diversity but reduced dominance. Redundancy analysis indicated that aboveground biomass (AGB), belowground biomass (UGB), and soil total copper were key environmental variables associated with variations in multiple soil functions. Linear regression analysis showed that fungal diversity indices, plant biomass (AGB and UGB), soil total cadmium, and soil total zinc exhibited significant linear relationships with SMF. Random forest analysis further identified UGB, bacterial Simpson index, and fungal Shannon–Wiener index as key predictors of SMF. Importantly, bacterial communities played a more important role in influencing SMF than fungal communities. These results advance the understanding of key drivers of ecosystem functional recovery in mine lands and provide a theoretical basis for optimizing soil function restoration strategies. Ultimately, these findings provide new insights for advancing efforts aimed at halting land degradation and safeguarding biodiversity in degraded mining ecosystems. Full article

Acidic tropical soils act as strong sinks for phosphorus (P) due to the high adsorption capacity of this nutrient by iron (Fe) and aluminium (Al) minerals. In this study, we investigated the effects of applying acai waste biochar (Euterpe oleracea Mart.) in combination with dolomitic lime on the P dynamics of a Ferralsol with cowpea (Vigna unguiculata (L.) Walp) test crop. Application of 12 t ha⁻¹ of biochar and 75% of the recommended lime rate increased soil pH by 1.77 units, reaching 6.77, and resulted in the lowest C:N ratio (18.99) at 0–5 cm depth. Inorganic P concentrations increased in Resin-Pi (2-fold), NaHCO₃-Pi (2-fold), NaOH-Pi (2.89-fold) and HCl-Pi (4-fold) fractions relative to the corresponding treatments without biochar, while NaHCO₃-Po decreased markedly, declining from 68% to 9% of the organic P fraction, NaOH-Po showed a less consistent response among treatments. In addition, P recovery in the Resin-Pi fraction increased, reaching 34.91% and 37.36% in the treatments with 12 t ha⁻¹ of biochar and both 75 and 100% liming, respectively. Combined use of alkaline biochar and lime is a practical strategy to raise pH and increase labile and moderately labile inorganic P, and improve P use efficiency in acid Ferralsols. These responses are consistent with a redistribution of P among the assessed fractions and with the absence of detectable short-term effects on arbuscular mycorrhizal fungi (AMF) colonisation and easily extractable glomalin-related soil protein (EE-GRSP) production. Full article

Ledum palustre (L. palustre) is widely used in drug development because of its antibacterial and analgesic effects. However, wild L. palustre is often affected by wildfires, resulting in unstable yields. Forest fires represent a major disturbance in northern forest ecosystems and profoundly affect shrub vegetation and its associated rhizosphere microbial communities. In this study, we investigated a fire chronosequence (1991, 2004, 2012, 2017, and 2020) to systematically examine the morphological traits of L. palustre, rhizosphere soil physicochemical properties, and microbial community characteristics and to identify the key drivers underlying these patterns. The results revealed that postfire recovery time significantly influenced the morphological traits of L. palustre. The biomass, branch number, basal diameter, and plant height of the shrubs at the 1991 burned site increased by 270.49%, 36.11%, 79.32%, and 191.36%, respectively (p < 0.05). From unburned soils, 29 bacterial and 29 fungal isolates were obtained, with Bacillus sp. and Oidiodendron sp. being the dominant culturable bacterial and fungal taxa, respectively. With increasing postfire recovery time, soil moisture, total nitrogen, ammonium, nitrate, soil organic carbon, acid phosphatase (AP) and N-acetyl-β-D-glucosaminidase (NAG) activity significantly decreased. Early fire disturbance markedly altered soil microbial abundance and community composition, leading to an overall decrease in bacterial α diversity. The bacterial community structure at the 2020 burn site and the fungal community structure at the 2012 burn site significantly differed. Mantel tests revealed significant positive correlations between branch number and basal diameter (p < 0.01) and significant negative correlations between plant height and stem density (p < 0.001). Soil carbon and hydrolysable nitrogen were significantly positively correlated with AP and NAG activities (p < 0.001). Moreover, soil physicochemical properties significantly shaped soil microbial community structures, with bacterial communities in early postfire sites driven by total carbon and nitrogen (p < 0.05), whereas fungal communities in the 2012 burned site were influenced primarily by β-N-acetylglucosaminidase (BG) activity (p < 0.05). Fire disturbance drives successional changes in the rhizosphere microbial community structure and function by altering the soil nutrient status and enzyme activity, which in turn influences the morphological traits of L. palustre. This study provides a theoretical basis for improving the yield of L. palustre by exploring the variation in rhizosphere microorganisms. Full article

Wildfires are among the key drivers of transformation in boreal ecosystems; however, the mechanisms of postfire recovery in the arid regions of Eurasia remain insufficiently understood. The aim of this study was to identify the role of burn severity and associated edaphic and hydrological factors in shaping the natural regeneration trajectories of Scots pine forests in the Kostanay region of northern Kazakhstan. This study is based on the integration of field data on seedling regeneration and soil conditions with the analysis of long-term satellite-derived indices (NDVI, NDMI, and NBR). Sample plots were grouped according to fixed burn severity classes, which enabled a consistent statistical comparison and reduced the interpretative ambiguity that has characterized previous studies in the region. The results indicate that pine forest regeneration is most successful under low and moderate burn severity, where seed sources are preserved and favourable moisture conditions are maintained. In contrast, high burn severity leads to a reduction in regenerative potential and a shift in recovery trajectories toward deciduous or sparsely vegetated communities. The spectral indices derived from the remote sensing data strongly agreed with the field-based indicators, confirming their suitability for assessing postfire vegetation dynamics. Soil properties act as important modifying factors of recovery processes, particularly under conditions of limited water availability. These findings enhance the current understanding of postfire recovery mechanisms in the arid part of the boreal zone and highlight the need for differentiated management of postfire landscapes. The integration of field observations with remote sensing data provides a robust framework for monitoring and forecasting recovery processes under an increasingly intensified fire regime. Full article

Soil nutrient loss and infertility in rocky desertification areas severely constrain ecological restoration. Exploring the impacts of external field remediation technologies on soil quality in these regions may offer novel strategies for soil enhancement and ecosystem recovery. This study conducted a three-month experiment to investigate the impact of continuous electric (ET, 20 V) and magnetic (MT, 200 mT) field treatments on soil nutrients, enzyme activities, and bacterial communities in simulated moderate and severe rocky desertification soils. Results showed that although an overall declining trends in total contents of key soil nutrients (Total nitrogen, total phosphorus, and total potassium), both electric and magnetic field treatments effectively mitigated the decreases of total nitrogen and potassium content (with the exception of total phosphorus) in rocky desertification soils, while improving their available contents compared to the control (CK). Electric field application significantly reduced the pH of moderate and severe rocky desertification soils through electrolysis, shifting the soil from alkaline (pH 7.69 and 7.73, respectively) to slightly acidic (pH 6.71 and 6.37, respectively); Both electric and magnetic field treatments enhanced urease and sucrase activities in moderately and severely rocky desertified soils. Compared to the CK, the increases were 21.92%, 4.46%, 5.70%, and 66.43% in moderately rocky desertified soil, and 10.06%, 42.15%, 20.66%, and 0.93% in severely rocky desertified soil, respectively. Their effects on phosphatase and catalase activities varied with the degree of rocky desertification. However, in severely rocky desertified soil, both treatments significantly increased phosphatase and catalase activities by 19.55%, 24.63%, 61.07%, and 38.05% compared to the CK, respectively. Furthermore, both electric and magnetic treatments significantly reduced bacterial α-diversity (chao1, ACE, Shannon, Simpson, and Pielou J indices) but optimized community structure by enriching dominant phyla with specific ecological functions, such as Pseudomonadota (7.63–41.10%), Bacteroidota (13.52–69.29%), and Verrucomicrobiota (38.26–104.81%). Functional prediction revealed that the abundances of dominant pathways (such as chemoheterotrophy, aerobic chemoheterotrophy, and nitrogen fixation) was enhanced following both treatments. Mantel analysis further indicated strengthened correlations among soil nutrients, enzyme activities, and bacterial communities, particularly under magnetic field treatment. These findings demonstrate that electric and magnetic field applications effectively facilitate nutrient cycling, stimulate enzyme activities, and optimize microbial community structure, thereby improving soil ecological functions and overall quality in rocky desertification regions, highlighting their potential for ecological restoration in karst areas. Full article

Soil salinity is a major abiotic stressor that constrains plant growth and development, yet the coordinated regulatory mechanisms underlying salt stress impacts on plant cell mechanical properties and the cytoskeleton remain elusive. In this study, tobacco suspension cells were employed as a model system. Combining mechanical measurements, fluorescence microscopy imaging, and bright-field morphological observation, we systematically characterized the dynamic response patterns of cell-generated surface stress (ΔS), cell viscoelastic index (CVI), microfilament cytoskeleton structure, as well as cell morphology and plasmolysis under NaCl stress ranging from 50 to 150 mmol/L. The results revealed three distinct response thresholds: 50 mmol/L NaCl treatment induced only transient ΔS fluctuations and mild plasmolysis, with no significant changes in CVI or microfilament fluorescence intensity, suggesting a safe tolerance threshold. The 75–100 mmol/L NaCl treatments triggered reversible “rise–recovery” mechanical responses in ΔS and CVI. The microfilament cytoskeleton showed minor structural adjustments, and plasmolysis increased gradually but remained reversible, defining this range as a reversible acclimation phase. The 125–150 mmol/L NaCl treatment caused an irreversible decline in ΔS (with a sharp instantaneous drop at 150 mmol/L). CVI variations diminished and stabilized after 6 h. The microfilament cytoskeleton suffered progressive disruption, as fluorescence intensity dropped to 1% of the control group at 150 mmol/L, accompanied by severe plasmolysis and protoplast shrinkage, indicating irreversible cellular damage. These findings demonstrate a concentration-dependent gradient effect of NaCl stress, highlighting tight coordination between mechanical properties, cytoskeletal integrity, and morphological adaptation. This work provides critical cytological insights into the molecular regulation of plant salt stress responses. Full article

Inadequate Municipal Solid Waste (MSW) management constitutes a critical environmental challenge, as approximately 40% of waste reaches uncontrolled disposal sites where open-air incineration generates significant air, soil, and water pollution. The objective of this study was to evaluate the MSW Environmental Management System (EMS) in Chilpancingo de los Bravo, Guerrero, Mexico, through sustainability indicators and applicable Mexican environmental regulations to identify operational and structural deficiencies that guide a comprehensive improvement in its management. The methodology comprised an analysis of the EMS via the Municipal Development Plan, the identification of environmental indicators and applicable Mexican standards, and an evaluation of the EMS through waste characterization and sustainability metrics. A sample of 208 kg was defined in accordance with standards NMX-AA-015-1985 and NMX-AA-022-1985. The results indicate a generation rate of approximately 350 tons per day (1.2 kg/capita/day), with municipal collection coverage of 70% of the territory across 24 daily routes operated by 30 vehicles. Indicators revealed a recycling rate of 4.86%, collection coverage of 79.66%, a 0% treatment rate due to the absence of composting or material recovery facilities, and 95% of waste directed to the Final Disposal Site (FDS). These findings demonstrate substantial deficiencies in the current EMS, highlighting that the systematic application of indicators is an effective diagnostic tool for identifying gaps and guiding evidence-based improvements in MSW governance. Full article

Optimizing nitrogen form under drip fertigation may improve wheat productivity by regulating the root-zone inorganic N environment during early vegetative growth. A two-year field experiment evaluated nitrate-dominant (N1), balanced ammonium–nitrate (N2), and ammonium-enriched nitrogen strategies (N3) during GS13–GS31, with conventional farmer practice (CK) and a zero-N control (N0) for comparison. Nitrogen-form regulation markedly altered the soil NH₄⁺-N ratios, especially in the 0–20 cm soil layer, with N3 highest, N1 lowest, and N2 intermediate. Compared with the nitrate- or ammonium-dominant strategy, the balanced treatment N2 improved spike formation rate and maintained relatively higher N accumulation at GS31 and GS65, and showed greater N translocation and contribution of translocated N to grain N than N1. Correlation analyses indicated that spike formation rate was closely related to spike number (R² = 0.764) and N accumulation at GS31 was positively related to Ntrans (R² = 0.588). N2 showed the most favorable overall performance, with the highest numerical values for grain yield, nitrogen recovery efficiency, irrigation water use efficiency, and net profit among the fertigation treatments. However, the advantages of N2 over N3 in grain yield and SPAD-AUC were modest and not consistently significant. These results indicate that balancing ammonium and nitrate supply during GS13–GS31 under drip fertigation can improve root-zone N conditions and support better overall agronomic performance in winter wheat under the alkaline soil conditions of the North China Plain. Full article