Search Results (416)

Against the dual backdrop of global ocean governance and food security, promoting the coordinated development of marine economic green development efficiency and inclusive growth is of significant practical importance for countries to improve marine ecology, narrow the wealth gap, and safeguard blue granary security. This study takes China’s three major marine economic circles and 11 coastal provinces from 2002 to 2024 as research subjects, employing methods including the Super-efficiency SBM model, the CRITIC-TOPSIS, Haken model, kernel density estimation, the Dagum Gini coefficient, and the ARIMA time series model to measure the spatiotemporal evolution of the synergy between marine economic green development efficiency and inclusive growth, as well as to forecast future trends. The results indicate that (1) the synergy level of the three major marine economic circles has been continuously increasing, with the full coastal zone’s synergy level rising from 0.48 in 2002 to 0.81 in 2024, with inclusive growth playing a dominant role throughout the period; (2) the synergy level of all Chinese provinces has been continuously improving with narrowing disparities—the Gini coefficient declined from 0.252 to 0.072, and the hypervariable density contributed an annual average of 47.22%; and (3) forecasts show that, from 2025 to 2029, the full coastal zone’s synergy level will rise from 0.82 to 0.84, with all economic circles showing an upward trend. The findings of this study can provide references for global coastal economies in formulating marine green sustainable development policies. Full article

Community capacity building in the Citarum River Basin is critical for sustainable environmental management through the principles of the Circular Economy (CE) and the Blue Economy (BE). This study developed an integrated modeling approach combining Structural Equation Modeling (SEM) and Machine Learning (ML) to analyze the effectiveness of CE- and BE-based training programs designed to strengthen community capacity in the Citarum River Basin. The factors examined include individual characteristics, teaching quality, and organizational and environmental support, with participant commitment serving as a mediating variable in influencing training effectiveness and sustainable environmental management outcomes. In this framework, SEM was employed to validate theoretical constructs and test causal relationships among latent variables, while ML techniques, specifically Random Forests and Artificial Neural Networks (ANNs), were incorporated to enhance predictive capabilities beyond what theory-driven models alone can achieve. The results demonstrate that all exogenous variables significantly influence training performance, both directly and indirectly, with organizational and environmental support as the most dominant factor, and that the integrated SEM-ML model outperforms the standalone SEM model. The integrated SEM-ML model yielded lower prediction error rates and higher explanatory power, with SEM-ANN delivering the best overall performance. These findings underscore the value of integrating theory-based and data-driven approaches in capacity-building research, effectively addressing the trade-off between model interpretability and predictive accuracy, and providing actionable insights for designing more impactful community training programs to support sustainable management of the Citarum River Basin. Full article

The global maritime sector is undergoing rapid transformation, creating an urgent need to align digital port technologies with a sustainable development framework. However, existing research on smart ports and the blue economy is fragmented and predominantly driven by deterministic approaches that overlook systemic complexity and uncertainty. This study develops a smart port system model grounded in blue economy principles, using a Bayesian network to analyze causal relationships among operational, environmental, and governance variables under uncertainty. The model incorporates key factors including port operational efficiency, logistics reliability, environmental compliance systems, coastal employment, and regulatory enforcement. The findings indicate that operational and logistical factors are the primary drivers of the system, while environmental and socioeconomic variables strongly shape sustainability outcomes. Scenario analysis shows that coordinated interventions targeting these key variables generate the greatest improvements in Smart Port–Blue Economy integration. Sensitivity analysis further identifies coastal economic output, regional competitiveness, and marine ecosystem health as the most responsive outcome variables. The research offers lessons for policymakers to enhance port management by integrating logistics and technological considerations with blue economy principles to design adaptive and resilient policies, particularly in island regions. Full article

European sustainability transitions are increasingly defined by the convergence of blue, green, and circular economy agendas. Traditionally analysed and governed in isolation, these domains generate important interdependencies, trade-offs, and coordination challenges that remain insufficiently understood. Drawing on the multi-level perspective (MLP) and recent advances in multi-system dynamics, this article introduces the Resource Infrastructure Economy (RIE) as a novel integrative framework. The RIE differs from existing multi-system frameworks by explicitly integrating marine governance as a full socio-technical regime, theorising regulatory-driven regime coupling as a distinct transition pathway, and foregrounding the constitutive role of shared physical and digital infrastructures in shaping value creation, path dependencies, and distributional outcomes. The RIE conceptualises contemporary European transitions as processes of deep regime coupling and infrastructural integration, whereby energy, marine, and material regimes become tightly coordinated through shared physical and digital infrastructures and assertive regulatory steering. Through a systematic integrative literature review (58 core publications selected from over 450 records following PRISMA guidelines, analysed using abductive thematic analysis with MAXQDA 26 software) and comparative analysis of six countries—Portugal, Spain, Denmark, Germany, the Netherlands, and Norway—the study reveals persistent structural gaps between the three agendas alongside emerging patterns of pairwise and triadic regime coupling. While Northern and Central European frontrunners demonstrate more advanced infrastructural coordination, Southern peripheral regions face greater difficulties in governance integration and just transition outcomes. The RIE framework advances sustainability transitions theory in three ways: (1) systematically integrating blue economy scholarship into multi-system analysis; (2) theorising regulatory-driven regime coupling as a distinct transition pathway; and (3) foregrounding the constitutive role of physical and digital infrastructures and environmental data systems in shaping value creation, path dependencies, and distributional outcomes. By reframing European sustainability transitions through the lens of the Resource Infrastructure Economy, this article provides a new conceptual lens to understand uneven transition geographies and offers actionable insights for more integrated and just policy coordination across the European Green Deal. Full article

Background: Climate action initiatives primarily target environmental outcomes, but their potential for health co-benefits through green and blue space contact remains understudied. Understanding these secondary outcomes could inform dual-purpose programming addressing climate and health challenges. Methods: This retrospective analysis examined 32 community-led climate action projects funded through Edinburgh Communities Climate Action Network (ECCAN) and their GreenLight programme (2024–2025). Projects spanned energy, transport, food, circular economy, and green space themes, with no formal health evaluation framework. Data were extracted from final reports covering 3195 direct participants. Results: Despite health not being a primary objective, 21 of 32 projects (66%) reported secondary health and wellbeing outcomes. Projects involving direct nature contact showed the strongest co-benefits: nine of ten high-nature-contact projects reported health benefits, compared to two of eight low-nature-contact projects. Notable outcomes included 94% of participants reporting increased willingness to engage in future community activities and 76% reporting mental wellbeing improvement following community garden workshops. Blue space engagement demonstrated particular significance for mental health and social cohesion. Conclusions: Green and blue space engagement in climate action projects consistently produces secondary health outcomes. We propose the Community–Environment–Health Nexus (CEHN) framework to understand how community-led environmental action generates synergistic health co-benefits. Full article

Small-scale vertical-axis wind turbines (VAWTs) are increasingly essential for the “blue economy,” providing autonomous power to remote coastal communities, offshore platforms, and marine industries. However, the design of efficient Darrieus-type rotors is complicated by complex unsteady aerodynamics, particularly the phenomenon of dynamic stall. This study aims to establish and validate a cost-effective yet accurate mathematical modeling approach for simulating unsteady turbulent flow around a Darrieus H-rotor to support practical engineering applications. The research methodology integrates computational fluid dynamics (CFD) with physical experiments in a hydrodynamic channel. The numerical model utilizes the unsteady Reynolds-averaged Navier–Stokes (URANS) equations closed with the Strain-Adaptive Linear Spalart–Allmaras (SALSA) turbulence model, chosen for its efficiency in capturing flow separation. The system of initial equations was being devised relatively to an arbitrary curvilinear coordinate system. The pressure and velocity fields have been coordinated using the artificial compressibility method adapted to calculate non-stationary problems. Experimental verification was conducted in the GT-400 hydrodynamic tube using a three-bladed H-rotor model, where flow structures were visualized via the colored jet method at tip speed ratios λ ranging from 2 to 5 and Reynolds number 1470. The findings reveal that dynamic stall occurs over a significant portion of the blade trajectory, characterized by vortex generation at the leading edge and subsequent advection along the chord. Qualitative comparison demonstrates a high degree of correlation between the calculated vortex dynamics and physical flow spectra. These results confirm that the URANS-SALSA approach provides a rational compromise between computational cost and physical accuracy. Full article

Contemporary Blue Planetary Health frameworks frequently approach marine degradation primarily as a technical management problem while insufficiently addressing the relational, ethical, and political–economic conditions driving ocean collapse. The framework proposes that dominant marine governance paradigms continue to reproduce anthropocentric and extractivist assumptions that reduce oceans to economic assets rather than recognizing them as living multispecies relational systems. In response, the study develops the Blue Stratified Relational Responsibility Framework (BSRRF), an interdisciplinary model integrating multispecies ethics, marine psychophysiology, environmental humanities, political ecology, Indigenous relational ontologies, and ocean governance. The framework advances three central claims: marine sustainability requires relational rather than purely instrumental governance; humans possess asymmetrical ecological responsibility due to their technological and institutional power; and meaningful Blue Planetary Health transformation requires simultaneous shifts in moral imagination, affective perception, governance systems, and political economy. The study further critiques dominant Blue Economy paradigms for reproducing extractivist and colonial dynamics under narratives of sustainability and innovation. Ultimately, the framework argues that although the ocean crisis manifests ecologically, its underlying drivers are simultaneously epistemological, political, economic, and civilizational. Consequently, advancing Blue Planetary Health requires integrated transformations in education, governance, public policy, and multispecies ethical responsibility. Full article

The increasing accumulation of mine waste and the associated release of toxic elements represent a major environmental challenge, particularly in regions impacted by Pb–Zn mining activities. In this context, this study aims to investigate the valorization of mine waste from Lakhouat, an abandoned Pb–Zn site in Northern Tunisia, as a sustainable additive in metakaolin-based geopolymers. This approach contributes to circular economy strategies by transforming hazardous waste into value-added materials for environmental and construction applications. Geopolymer formulations were synthesized by incorporating mine waste at different proportions (0, 5, 10, 20, and 30 wt.%) with metakaolin, while maintaining constant SiO₂/Al₂O₃ and Na₂O/Al₂O₃ molar ratios. The materials were prepared through alkali activation using sodium silicate and sodium hydroxide, followed by curing. Comprehensive characterization was carried out using X-ray fluorescence (XRF), X-ray diffraction (XRD), and scanning electron microscopy (SEM). In addition, adsorption experiments using methylene blue (MB) were conducted to evaluate the environmental performance of the synthesized geopolymers. The results revealed that the mine waste contains high concentrations of potentially toxic elements (up to 2.23 wt.% Pb and 8.2 wt.% Zn), highlighting the need for effective stabilization. Microstructural analysis confirmed the formation of predominantly amorphous geopolymer matrices with varying degrees of reaction depending on MW content. The highest compressive strengths (25–30 MPa) were achieved for formulations containing 5–10 wt.% MW after 28 days of curing. Furthermore, the geopolymers demonstrated efficient methylene blue removal, following pseudo-second-order kinetics and fitting the Langmuir isotherm model, with enhanced adsorption performance observed at higher MW contents. These findings indicate that MW-based geopolymers are promising materials for mine waste valorization and methylene blue removal. However, standardized leaching tests are required to confirm the long-term immobilization of Pb, Zn, Cd, As, and other potentially toxic elements within the geopolymer matrix. The study highlights their potential as sustainable, low-impact materials, supporting waste valorization and contributing to the development of environmentally resilient systems within a circular economy framework. Full article

The red macroalga Kappaphycus alvarezii, widely cultivated for carrageenan extraction, has emerged as a promising blue economy resource of bioactive compounds for sustainable agriculture. However, knowledge regarding the composition, mechanisms of action, agronomic effects, and large-scale applicability of K. alvarezii-based products remains fragmented. Therefore, this review provides an overview of the potential of K. alvarezii and its by-products for the development of agricultural bioinputs, addressing species diversity, cultivation practices, chemical characterization of bioactive compounds, and their agronomic applications. Literature evidence indicates that K. alvarezii biomass is rich in sulfated polysaccharides, phenolic compounds, photoprotective pigments, fatty acids, and metabolites with hormone-like activity, which have been associated with enhanced plant growth, increased photosynthetic efficiency, and improved tolerance to biotic and abiotic stresses, resulting in productivity gains in crops such as rice, maize, sugarcane, soybean, and vegetables. In addition, biomass represents a potential source of potassium and micronutrients that can complement conventional fertilization. Recent technological advances, as well as regulatory aspects and challenges related to the integration of these products into the global agricultural market, are also discussed. Overall, the evidence highlights the potential of K. alvarezii as a renewable resource for the development of innovative agricultural bioinputs, as biofertilizers and plant biostimulants. Full article

Valorization of agro-industrial waste into functional materials is fundamental to the circular economy, especially for addressing the persistent contamination by anionic azo dyes in textile wastewater. This study evaluates guava seeds modified with hexadecyltrimethylammonium bromide (GS-M) as low-cost biosorbents for the removal of Direct Blue 71 (DB71), comparing their performance with that of natural seeds (GS-N) in batch systems and fixed-bed columns. Characterization by infrared spectroscopy (FTIR) and electron microscopy (SEM-EDS) confirmed successful surfactant immobilization, thereby creating a cationic surface with strong electrostatic affinity for anionic dye molecules. Batch experiments showed that GS-M achieved 98% DB71 removal within 120 min, whereas GS-N reached only 58% after 300 min. For GS-M, both pseudo-first-order and pseudo-second-order models fit the kinetic data well, consistent with concurrent electrostatic and hydrophobic interactions; GS-N was best described by the Elovich model, indicating rate limitation by electrostatic repulsion. GS-M maintained removal efficiency above 84% across pH 3–9, whereas GS-N was effective under acidic conditions. Langmuir maximum adsorption capacity (Q_o) values for GS-M were 6.02 mg/g at pH 4 and 7.87 mg/g at pH 8, a 1.5- to 2.2-fold increase over GS-N under matched conditions. Three adsorption–desorption cycles retained ~49% of the initial GS-M capacity, supporting a short-cycle reuse profile rather than indefinite multi-cycle operation. Fixed-bed column performance was highly sensitive to the hydraulic loading rate (v_c), with breakthrough times increasing nearly eightfold as v_c decreased. The Bed Depth Service Time (BDST), Thomas, and Yoon–Nelson models described the dynamic data consistently, yielding a maximum dynamic capacity of 165.6 mg/L under optimal conditions and providing a quantitative basis for scale-up. These results establish surfactant-modified guava seeds as a low-cost, pH-resilient biosorbent system aligned with circular-economy principles for the sustainable remediation of textile wastewater. Full article

This study investigates the potential of several sustainable agricultural by-products—including olive stones, cork, and almond shells, which are locally available in Alentejo, Portugal—as low-cost adsorbents for the removal of methylene blue (MB) from synthetic wastewater. The biomass residues were evaluated both in their raw form and after conversion into activated carbons (ACs) through chemical activation with KOH at 973 K. The produced ACs exhibited well-developed surface areas (760–1103.5 m² g⁻¹) and porous structures (0.31–0.51 cm³ g⁻¹). The adsorbents were characterised in terms of their chemical and textural properties. Raw biomass materials presented acidic surface groups, whereas the ACs presented neutral or basic groups. Batch adsorption experiments were conducted to assess the effects of adsorbent particle size, solution pH, initial MB concentration, stirring speed, contact time, and temperature on dye removal efficiency. Among all tested materials, the ACs achieved superior MB adsorption capacities, ranging from 244.2 to 317.6 mg g⁻¹, compared to the untreated biomass adsorbents, which showed capacities between 34.1 and 46.4 mg g⁻¹. The adsorption data were best described by the Langmuir isotherm model, while the kinetic data closely followed the pseudo-second-order (PSO) model. Thermodynamic analysis revealed that MB adsorption was spontaneous and endothermic; however, the relatively low enthalpy values indicated that physical interactions contributed significantly, particularly in the case of the raw biomass adsorbents. This suggests that the PSO model may also be applicable when physical adsorption is the dominant mechanism. This work demonstrates the novel use of cork, olive stone, and almond shell biomasses and their derived ACs as sustainable adsorbents, highlighting an integrated approach that simultaneously promotes efficient wastewater treatment, waste valorisation, and circular economy-driven socio-economic development. Full article

Food loss and waste (FLW) represent a significant source of resource inefficiency in water-scarce economies. This study quantifies the water footprint (WF) of FLW in Saudi Arabia using product-level blue, green, and grey WF coefficients from the Water Footprint Network database. Our analysis covers 3.997 million tons of FLW across 19 commodities grouped into cereals, fruits, vegetables, and meat. Results indicate that FLW is associated with a total blue and green WF of 7.3 billion m³, of which 2.1 billion m³ is blue water directly associated with managed water resources. The blue WF is equivalent to approximately 20% of agricultural water withdrawals and 62% of domestic water demand. Despite constituting only 13% of total FLW by mass, meat products account for 53% of the total water footprint, driven by their exceptionally high water intensity (7474 m³/ton). The consumption stage dominates water losses, contributing 56% of the total blue and green WF. Based on alternative water supply cost benchmarks, the blue WF embedded in FLW corresponds to an indicative production-cost equivalent ranging from 1.03 to 6.5 billion SAR. A 25% reduction in FLW could save over 500 million m³ of blue water annually. These findings demonstrate that FLW reduction represents an important supporting strategy for water resource management and provides a quantitative basis for prioritizing intervention across food groups and supply-chain stages. Full article

The intensifying global challenges of environmental degradation, escalating energy demands, and unsustainable waste accumulation necessitate the exploration of alternative, high-value biomass resources. Algal biomass has emerged as a uniquely versatile and sustainable candidate, offering transformative potential across a broad range of industrial and environmental sectors. This review comprehensively evaluates the recent advancements and multidisciplinary applications of algae, with a strong emphasis on their distinctive chemical composition, bioactive compounds, and environmental adaptability. The novelty of this review lies in its integrative scope, which spans from algae cultivation, production, and trade to cutting-edge extraction technologies for bioactive constituents. Furthermore, the review presents a detailed exploration of algae’s functionality as a feedstock for biofuels, pharmaceuticals, sustainable agriculture, bioplastics, green chemistry, and water treatment, positioning it as a cornerstone in the development of the blue economy. By critically analyzing both conventional and innovative applications, this work contributes to a deeper understanding of algae’s strategic role in shaping a sustainable and resilient bioeconomy. Full article

Waste-to-hydrogen (W2H) technology is gaining recognition as a viable pathway for simultaneous waste valorisation and clean energy production in the Gulf Cooperation Council (GCC). However, the water resource implications of hydrogen production pathways in this acutely water-scarce region have received insufficient analytical attention. This paper presents the first systematic comparative analysis of water consumption across grey, blue, green, and waste-to-hydrogen production pathways calibrated to the GCC context, using the ISO 14046 water footprint framework and accounting for the desalination penalty that arises when hydrogen facilities draw on energy-intensive desalinated water. The analysis shows that green hydrogen, widely promoted in GCC national hydrogen strategies, incurs a compound water–energy burden substantially greater than global benchmark figures suggest, with electrolysis requiring 9 to 18 litres of water per kilogram of hydrogen and desalination accounting for 4 to 20 per cent of GCC electricity consumption. In contrast, W2H gasification exhibits considerably more modest water demands at 10 litres per kilogram of hydrogen, with high potential for treated wastewater substitution and co-location with municipal waste infrastructure, positioning it as the most water-compatible near-term hydrogen production pathway for arid GCC economies. Drawing on the water–energy nexus and water governance literature, the paper proposes a Water–Hydrogen Governance Framework comprising four policy pillars: water efficiency standards for hydrogen production facilities, water allocation policy for industrial hydrogen projects, integrated water–energy planning at the national level, and regional GCC coordination on water–hydrogen governance. The framework is aligned with SDGs 6, 7, 13, and 17 and provides a structured and practical tool for GCC governments and development institutions seeking to integrate water security into hydrogen strategy. The findings contribute to the emerging literature on resource-constrained hydrogen deployment and offer a replicable governance model for other arid economies pursuing clean hydrogen transitions. Full article