Search Results (351)

Industrial effluents containing zinc, cadmium, and nickel represent both an environmental challenge and a valuable secondary resource. This study investigates the simultaneous recovery of Zn(II), Cd(II), and Ni(II) from nitric acid solutions using di-(2-ethylhexyl) phosphoric acid (D2EHPA) dissolved in commercial diesel fuel in a continuous counter-current semi-pilot mixer–settler extraction system. The effects of key operating parameters, including aqueous-phase pH, initial metal concentration, phase ratio, contact time, stirring speed, and stripping agent, were systematically evaluated. Metal concentrations were determined by atomic absorption spectrometry, while Fourier-transform infrared spectroscopy was employed to investigate the extraction mechanism. The optimum operating conditions were pH 2.45 for Zn(II) and pH 5.38 for Cd(II) and Ni(II), a phase ratio of V_A/V_O = 1.5/3.5, and a stirring speed of 700 rpm. Under these conditions, high extraction efficiencies were achieved, with Zn(II), Cd(II), and Ni(II) recoveries of 98.52%, 76.86%, and 84.04%, respectively. FTIR characterization, together with slope analysis, suggested a dimeric cation-exchange extraction mechanism involving D2EHPA species in the organic phase. Among the stripping agents evaluated under the present experimental conditions, 0.5 M H₂SO₄ produced the highest stripping efficiencies for Zn(II), Cd(II), and Ni(II). Although the stripping efficiencies remained moderate, particularly for Cd(II) and Ni(II), these results demonstrate the relative effectiveness of H₂SO₄ compared with the other stripping agents examined. Further optimization of the stripping conditions is expected to improve metal recovery. The proposed process shows significant potential for industrial wastewater treatment, metal recovery, and resource valorization. Full article

Oil-contaminated soils represent a significant environmental challenge due to the presence of petroleum hydrocarbons and associated pollutants. At the same time, such materials may contain valuable hydrocarbon-rich organic fractions that can potentially be recovered and reused. In this study, the organic phase extracted from oil-contaminated soil was investigated as a secondary hydrocarbon resource for the production of bitumen-like materials. The extracted organic phase was subjected to thermal oxidation to obtain a bitumen-like material, followed by modification using road bitumen (BND 50/70) and an SBS polymer. The resulting bitumen-like material exhibited improved performance after modification, with the softening point increasing from 32.1 to 40.6 °C, the rotational viscosity from 3.11 to 101.5 Pa·s, and enhanced high-temperature rutting resistance. The structural and compositional characteristics of the obtained materials were analyzed using FTIR spectroscopy, nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), and Saturates, Aromatics, Resins, and Asphaltenes (SARA) fractionation. Physicomechanical and rheological properties were evaluated using penetration, softening point, rotational viscosity, and dynamic shear rheometer (DSR) measurements. The results indicate the presence of aliphatic and aromatic hydrocarbon-rich structures characteristic of petroleum-derived materials. Modification with road bitumen and SBS resulted in redistribution of SARA fractions and improved physicomechanical and rheological properties, including increased softening point, higher viscosity, and enhanced resistance to permanent deformation at elevated temperatures. Overall, the obtained results demonstrate that oil-contaminated soils can be considered a promising secondary source of hydrocarbon-rich raw materials. The proposed approach combines waste remediation with resource recovery and supports the development of sustainable technologies for the utilization of petroleum-containing wastes within a circular economy framework. Full article

This study employs the sustainable livelihoods framework to examine the achievements and challenges of the community-based natural resource management (CBNRM) program, with an emphasis on wildlife-based tourism development in Botswana. The article analyses whether the CBNRM program in its 30-year history has achieved its main goal of improving rural livelihoods and promoting conservation in Botswana. The article used secondary data, supplemented by primary data collected through personal observations and interactions with key people in the tourism and conservation sectors. The paper argues that the proper implementation of CBNRM can enhance rural livelihoods and contribute to the conservation of biodiversity. In Botswana, wildlife-based tourism generates economic benefits, including employment opportunities and income, which in turn fosters positive attitudes among residents towards conservation and tourism. CBNRM also faces difficulties; reviews show that wildlife-based tourism employment provides low wages, and after reaching a certain age, residents become impoverished because they cannot participate in the formal labor force and have no alternative means of support because of their locations, where other livelihood options, such as agriculture, which is a legacy in most of Botswana, are illegal or unfavorable. Benefits from wildlife-based tourism are inequitably distributed among age groups. Employment monopolizes benefits. This situation occurs because most community-based organizations (CBOs) fail to allocate benefits from CBNRM ventures directly to households, where the costs of coexisting with wildlife are incurred; instead, benefits are disbursed to villages. The results also indicate that in Botswana, most of the successful and sustainable CBNRM CBOs benefiting from wildlife-based tourism through joint ventures were initially established during the introduction of CBNRM in the 1990s. CBOs that registered later are struggling to venture into wildlife-based tourism because of insufficient managerial and entrepreneurial competencies within the tourism industry, insufficient training and capacity development in CBNRM, and other factors limiting communities from benefiting from wildlife-based tourism. These village community members continue to regard wildlife as state property because they lack projects that give them a sense of ownership over wildlife species, raising questions about whether CBNRM is meeting its aim of improving livelihoods and conservation. This evidence reveals that Botswana has not utilized most of its wildlife-based tourism potential. Full article

To address the challenges in remote monitoring of power system secondary equipment, including dispersed multi-source heterogeneous corpora, inconsistent terminology, non-standardized expressions, unstable knowledge granularity, and fragmented evidence retrieval, a knowledge-organized and retrieval-augmented intelligent decision-making model is proposed in this paper. First, heterogeneous textual resources, including defect records, standards and operating procedures, maintenance logs, typical cases, and abnormal operation reports, are transformed into retrievable, reusable, and traceable knowledge units through text cleaning, terminology normalization, semantic chunking, and metadata annotation. Monitoring issues are then uniformly represented and modeled as structured retrieval requests. A hybrid retrieval scheme is further developed by integrating keyword retrieval, vector retrieval, hierarchical index backtracking, and unified re-ranking. On this basis, an evidence-constrained retrieval-augmented output mechanism is introduced to generate structured results containing anomaly assessment, evidence-based interpretation, handling recommendations, and source traceability, thereby forming an intelligent auxiliary analysis workflow with expert-system-oriented support for duty-operation scenarios. Results show that the proposed model improves evidence retrieval over baseline retrieval settings and achieves better assisted-analysis performance than direct LLM output and conventional RAG. It effectively improves evidence matching accuracy, completeness of evidence organization, and stability of source traceability, indicating its scenario-level feasibility for intelligent auxiliary analysis and decision-support tasks in remote monitoring of power system secondary equipment. Full article

This study aims to assess the impact of the October 2023 Gaza War on water and sanitation systems and propose actionable solutions for effective management. The study adopted a mixed-methods approach (quantitative and qualitative). Primary data were collected through semi-structured interviews, targeted questionnaires, and direct field observations. Secondary data were gathered from reports by international organizations (UNRWA, OCHA, WHO), Palestinian authorities, academic research, in addition to satellite imagery and Geographic Information System (GIS) data for damage assessment. The results showed that the institutional level of emergency preparedness before the war varied significantly. Despite the existence of pre-developed emergency plans (mean score 3.26, relative weight 65.28%, p = 0.0355), there were significant shortcomings in practical staff training (mean score 2.64, relative weight 52.83%, p = 0.006), logistical readiness, and the activation of international partnerships. The study also revealed major challenges faced in providing water and sanitation services during the war, including fuel and resource shortages, safety risks for field teams, weak coordination with security agencies, lack of materials and equipment, insufficient emergency funding, coordination gaps, staff displacement, communication breakdowns, difficulty accessing water sources, area division and blockade, and loss of personnel. Specifically, the inability to access water sources was a critical challenge (mean score 4.30, relative weight 86.04%, p < 0.0001), as was indiscriminate shelling impacting field team safety (mean score 4.19, relative weight 83.77%, p < 0.0001) and lack of materials and equipment (mean score 4.15, relative weight 83.02%, p < 0.0001). Residents reported water availability only every 10–15 days, and over 70% of water and sanitation systems were damaged. While funding proposals were being prepared (mean score 3.26, relative weight 65.28%, p = 0.02), weaknesses in reporting systems and coordination of roles were observed (mean score 2.55, relative weight 50.94%, p < 0.0001). The research contributes to guiding local and international efforts towards reconstruction, enhancing resilience, and ensuring the provision of safe drinking water and adequate sanitation for the affected population, thereby reducing the risks of waterborne diseases and improving public health. Full article

Soil microbial carbon use efficiency (CUE) and nitrogen use efficiency (NUE) are fundamental parameters governing organic matter turnover in terrestrial ecosystems, yet how forest type-driven variation in litter quality propagates through the litter–soil–microbe continuum to regulate these efficiencies remains poorly resolved. Across three forest types in the Funiu Mountains, central China—a Larix gmelinii (LG) plantation, a Quercus aliena var. acuteserrata (QA) secondary forest, and a mixed Quercus aliena var. acutiserrata and Pinus armandii (QP) forest—we quantified litter chemistry, soil physicochemical properties, microbial biomass, extracellular enzyme activities, and microbial nutrient use efficiencies (MUE: NUE, and phosphorus use efficiency, PUE) derived from a modified saturation kinetics model. Principal coordinate analysis revealed significant multivariate differentiation among forest types across litter, soil, microbial biomass, and enzyme modules (Adonis R² = 0.198–0.427; all p < 0.05). Compared with LG and QA, QP exhibited a pronounced stoichiometric imbalance: it supported the highest litter organic carbon and total nitrogen, the lowest lignin-to-cellulose ratio, the largest soil C and N pools (SOC and STN), and the greatest microbial biomass carbon (MBC). However, despite this resource-rich environment, microbial biomass C:N:P ratios exhibited constrained variation, while soil C:P (SCP) and N:P ratios (SNP) in QP reached extreme values (112.3 and 7.25, respectively), generating severe stoichiometric imbalance. Vector analysis indicated that all forests were under relative nitrogen limitation (vector angle < 45°), with QP showing the strongest limitation (41.6 ± 0.4°). Critically, QP exhibited the highest NUE (0.47 ± 0.03) but the lowest CUE (0.95 ± 0.01), and CUE and NUE were nearly perfectly negatively correlated across all sites (R = −0.98, p < 0.001). Random forest analysis identified extracellular enzyme stoichiometry as the dominant proximate predictor of MUE. Partial least squares structural equation modeling (GOF = 0.673–0.674; R² = 0.592–0.603) revealed that litter and soil properties had no significant direct effects on CUE or NUE; instead, soil nutrients exerted strong indirect association through a cascade—soil → microbial biomass → enzyme activity—with opposite total effects on CUE (−0.731, p < 0.001) versus NUE (+0.755, p < 0.001). These findings reveal that the same soil nutrient enrichment that accompanies mixed-species afforestation drives divergent microbial metabolic responses—suppressing CUE while promoting NUE—through a shared cascading structure, with implications for predicting soil carbon and nutrient retention under shifting forest compositions. Full article

Large-scale mining of rare earth resources has caused a series of ecological and environmental problems in mining areas, including soil structural degradation, nutrient depletion, acidification, and rare earth element (REE) accumulation. Conventional physicochemical remediation technologies are often limited by high costs, strong disturbance, and insufficient long-term stability. To compare the effects of different vegetation types on ecological restoration of ion-adsorption REE tailing soils, this study was conducted in an abandoned REE tailing area in Changfeng’ao, Ganxian District, Ganzhou City, Jiangxi Province. A small-scale field restoration experiment was established with three treatments: unrestored tailings (CK), slash pine (PE), and broadleaf paspalum (CS). Soil physicochemical properties, REE concentrations, bacterial and fungal community structures, and untargeted metabolomic profiles were comprehensively analyzed. Compared with CK, both PE and CS increased soil organic matter, alkali-hydrolyzable nitrogen, and available potassium and were associated with lower concentrations of several REEs, including Dy, Nd, Er, Y, and Yb, whereas the response of Ce differed between vegetation types. The two vegetation treatments exerted inconsistent effects on microbial communities: PE significantly increased bacterial richness and Shannon index and increased fungal richness, but decreased fungal Pielou evenness and Shannon index; in contrast, CS did not markedly enhance bacterial alpha diversity. Community composition analysis showed that vegetation treatments altered the relative abundances of dominant bacterial and fungal taxa, which were closely associated with changes in pH, soil organic matter, nitrogen, phosphorus and potassium nutrients, and REEs. Metabolomic analysis indicated that fatty acyls, organooxygen compounds, and carboxylic acids and derivatives were the major classes of differential metabolites. Pathways such as ABC transporters, nicotinate and nicotinamide metabolism, purine metabolism, and secondary metabolite biosynthesis may participate in soil metabolic reshaping under vegetation restoration. Overall, this study indicates that broadleaf paspalum and slash pine have differentiated ecological effects in REE tailing restoration and provides preliminary field evidence for vegetation recovery and soil microecological reconstruction in REE mining areas of southern Jiangxi. Full article

Platinum group metals (PGMs) play a key role in many industries. However, the growing demand for PGMs, the systematic decline in their natural resources, and the generation of large amounts of waste, constituting a secondary source, are closely related to the search for effective and environmentally safe methods for their separation. Although solvent extraction (SX) processes, long used to extract PGMs from various ores/waste leachates, typically allow for effective separation of these valuable metals, they rely primarily on the use of organic solvents, many of which are environmentally hazardous. Therefore, recent research efforts have focused, among others, on the utilization of potentially “greener” chemicals, such as ionic liquids (ILs) and deep eutectic solvents (DESs). Due to their tunable properties to specific applications, these chemicals usually enable not only efficient (often >90%) but also selective and more eco-safe separation of PGMs from various matrices. This review concerns the latest developments in the SX of PGM ions from aqueous solutions and suspensions using ILs and DESs (e.g., as extractants, solvents, and leaching agents), taking into account their most important advantages, limitations, and potential impact on the environment. IL- and DES-based SX methods fit into the green chemistry trend and are consistent with sustainable development goals. Full article

Large-scale breeder chicken farms generate high-moisture manure, and all-in/all-out management can constrain continuous manure handling, especially during cold northern winters. This study proposed and evaluated a staged resource-recovery pathway for breeder chicken manure under all-in/all-out farm management. The pathway consisted of an implemented on-farm primary aerobic fermentation stage for rapid reduction and sanitization, an implemented centralized secondary aerobic fermentation stage for standardized organic fertilizer production, and a proposed solar-greenhouse-assisted low-temperature module for seasonal continuity support. System performance was assessed through a practice-based case evaluation using enterprise operational records, field investigations, and routine monitoring data on manure generation, process parameters, product quality, and logistics/cost indicators. The primary stage showed a relatively stable operational window across case farms, with fresh manure moisture contents of 85–90%, compost temperatures increasing from approximately 30 °C to 60 °C before declining to about 40 °C, and pH values ranging from 7.0 to 9.5, while batch duration and moisture-control pathways varied among farms. The secondary stage demonstrated standardized downstream processing capacity; the tested organic fertilizer complied with NY/T 525-2021, while the bio-organic fertilizer specifications met the benchmark requirements of NY 884-2012. The conceptual winter continuity-support module was discussed as a conceptual engineering supplement requiring future operational validation. Overall, the evaluated pathway may provide a practice-based reference for sustainable manure management, standardized fertilizer production, and circular agricultural resource recovery under intensive breeder chicken production conditions. Full article

Background/Objectives: Widely distributed in the Adriatic Sea, the invasive green alga Caulerpa cylindracea poses ecological risks but also constitutes a largely untapped source of bioactive compounds. This study aimed to characterize its metabolomic profile, phenolic composition, and antioxidant capacity to explore its potential for biotechnological use. Methods: Samples from the Northern Adriatic Sea were extracted with water, 70% ethanol, and 80% methanol. Phenolic compounds were analyzed by LC-QqQ, while untargeted metabolomic profiling was performed using LC-qTOF. Total phenolic, flavonoid, and non-flavonoid contents were determined spectrophotometrically, and antioxidant activity was evaluated using DPPH, ABTS, and FRAP assays. Results: Metabolomic profiling demonstrated a clear solvent-dependent differentiation, with aqueous extracts enriched in polar metabolites, while organic extracts contained higher levels of lipid-derived and secondary metabolites. Antioxidant assays indicated that aqueous extracts exhibited the strongest radical-scavenging activity (DPPH and ABTS), whereas the highest reducing capacity (FRAP) was observed in ethanolic extracts. In addition, total flavonoid content was greatest in the ethanol extracts. Conclusions: These results highlight its potential for valorization as a sustainable resource in food, cosmetic, and biomedical applications, while also supporting approaches for managing its spread. Full article

Lilac (Syringa oblata Lindl.) is an important eco-economic aromatic shrub in northern China; however, the key volatile organic compounds (VOCs) responsible for its floral aroma and their origin remain largely unexplored. In this study, we conducted an integrated analysis of volatile metabolomics and transcriptomics to elucidate the composition, dynamic changes, and potential regulatory network of VOCs across different floral organs and petal developmental stages. A total of 1440 VOCs were identified in the stamens, pistils, and petals, with petals being the primary contributors to the overall floral aroma. Analysis of different petal developmental stages revealed that the full-bloom stage (S3) is critical for VOCs emission. The floral aroma of S. oblata is primarily composed of terpenoids, alcohols, and aldehydes. By relative odor activity value (rOAV) with multivariate statistical screening, seven key VOCs with high contributions to the floral aroma were identified. Transcriptome analysis identified 69,935 differentially expressed genes (DEGs) across petal developmental stages, which were predominantly enriched in metabolic pathways and the biosynthesis of secondary metabolites. The expression patterns of these DEGs were highly consistent with the accumulation trends of VOCs, increasing at stages S2 and S3 and subsequently declining at stage S4. Integrative analysis of VOCs and gene expression further identified candidate genes significantly correlated with the key aroma volatiles. Specifically, the carotenoid pathway-related genes CYP97A3 and LYC may influence the formation of carotenoid-derived volatiles and floral aroma. Additionally, genes associated with the fatty acid-lipoxygenase pathway, transport-related genes, and transcription factors are potentially involved in the formation and regulation of aldehyde and alcohol volatiles. These findings advance our understanding of the floral aroma formation in S. oblata and provide metabolic basis, candidate gene resources and a theoretical foundation for the genetic improvement of aroma traits and the breeding of new cultivars. Full article

Freshwater scarcity is driving the construction industry to seek alternative mixing waters, and seawater is an abundant resource; however, its suitability is commonly judged by total salinity, which overlooks the fact that coastal seawater chemistry varies hugely between locations and may govern long-term strength performance in varying locations. To address this problem, this study investigates the long-term strength performance and its microstructural and phase transformation of cement mortars mixed with seawater, with the aim of establishing a technical understanding between region-specific seawater chemistry and mortar strength. Seawater was collected from four coastal locations in Tamil Nadu, India, and characterized for chloride, sulfate, magnesium, organic solids, and related parameters. The cement mortar cubes were cast with each seawater, and compressive strength was measured from 3 to 360 days; the microstructural and phase changes underlying the strength behavior were examined at 360 days using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). All samples showed accelerated early-age strength gain from the catalytic effect of chloride and sulfate ions, followed by strength loss at later ages caused by the same ionic environment, with a critical strength loss between 28 and 56 days. The Chennai sample, with the highest chloride and sulfate concentrations, suffered the most severe degradation of 11.5% loss of peak strength, which is attributed to ettringite and gypsum formation together with magnesium attack that consumed Portlandite to form non-cementitious brucite and secondary Calcite. In contrast, the Rameshwaram sample, with exceptionally low sulfate, exhibited superior stability with 3.5% loss, while Puducherry and Tuticorin showed intermediate degradation of 3.9% and 7.8% respectively, with the Puducherry sample further compromised by high organic solids. The results identify the chloride to sulfate ratio, rather than total salinity, as the key predictor of long-term strength performance. The main takeaway for the cement industry is that the suitability of seawater as mixing water is highly site-specific, and a detailed chemical analysis quantifying sulfate and magnesium content is an indispensable prerequisite for strength assessment and material selection before seawater is adopted in marine and coastal construction. Full article

Brown algae are important primary producers in coastal ecosystems, where they provide habitat and food for numerous marine species. For humans, they provide raw materials (food, animal feed, and ingredients for pharmaceuticals and cosmetics) as well as ecosystem services such as coastal protection and carbon sequestration. The molecular characterization of brown algae is necessary to understand their role in ecosystems, their biochemical resources, and responses to environmental stresses—knowledge that is crucial for the sustainable use and biotechnological applications of seaweed. Within this context, we analyzed more than 300 primary and secondary metabolites by gas chromatography–mass spectrometry to elucidate the metabolic profiles of seven habitat-forming species of brown algae in the arctic and temperate seas. Metabolite profiles were discussed considering physiological and ecological characteristics of the different algae, thus revealing the taxon-specific biochemical signatures and metabolite patterns contributing to seaweed adaptation to their typical habitats. Three important groups of metabolites representing polyols, phenolic compounds, and organic acids, were analyzed and discussed in more detail. Our study revealed metabolic diversity of species from the same order and genus, thereby indicating a very distinct regulation at the molecular level to meet metabolic needs of the habitat. The knowledge of different compositions of algal extracts can be used to develop specialized applications for humans in cosmetic, medical, or nutritional sectors. Full article

Small and medium-sized enterprises (SMEs) are particularly vulnerable when crisis support systems are delayed, unreliable, or difficult to access. This study examines how South African SMEs maintained strategic continuity during COVID-19 by developing the concept of relational substitution, defined as a process in which owner-managers compensate for weak formal support by internalizing continuity work within the employment relationship. The study is based on a secondary qualitative analysis of 16 semi-structured interviews with SME owners in the Western Cape, South Africa, complemented by a targeted evidence review to inform boundary-condition assessment. The findings show that owner-managers assembled relational continuity bundles that combined labor flexibility, retention intent, transparent communication, and visible well-being support. Owners presented these bundles as efforts to sustain cooperation, trust, and operational functioning when enacted through fairness logics such as voice, transparency, equal sacrifice, and relational care. The study contributes to SME resilience and management and organization studies by distinguishing relational substitution from sustainable human resource management, organizational justice, relational leadership, and institutional fragility, and by specifying the firm-level and institutional conditions under which this mechanism is more likely to support strategic continuity. Full article

Plant–plant interactions in agroecosystems are shaped by both biochemical interference and resource-mediated competition, yet the relative contribution of these mechanisms under field conditions remains unclear. This study evaluated whether allelopathic activity expressed by winter cereal rye (Secale cereale L.) and grain legumes under controlled conditions is associated with competitive outcomes in relay-row intercropping under organic farming. Greenhouse bioassays and laboratory screening assays were combined with a field experiment conducted under certified organic farming conditions. Aqueous leachates and biomass extracts influenced early root development of a sensitive recipient species in a time- and concentration-dependent manner, indicating measurable biological activity. Secondary metabolite profiles differed significantly among species, particularly in belowground biomass. However, under field conditions, no persistent suppression of grain legumes was observed. Aboveground biomass accumulation and land equivalent ratio (LER) values exceeded 1.0 in all intercrops, with the highest LER recorded for the cereal rye–lentil combination. The results suggest that under the conditions of this study, resource partitioning, species compatibility, and other ecological interactions may have had a greater influence on intercrop performance than the allelopathic effects detected under controlled conditions. Full article