Wei Zhang

The water source area of the Henan Reach for the South-to-North Water Diversion Project is an important ecological protection zone, where variations in land-use patterns can adversely affect the region’s carbon sink capacity and long-term ecological stability. To examine the spatiotemporal distribution of carbon sinks and clarify the underlying factors driving their changes, an analytical framework combining PLUS, InVEST, and GeoDetector was applied. Xichuan County, Xixia County, Neixiang County, and Dengzhou City—four administrative units in Nanyang City that together form the Henan water source zone of the Middle Route—were selected as the research areas. Land-use records from 2002 to 2023 were analyzed to identify changes in the production–living–ecological (PLE) land-use structure and carbon storage dynamics through 2030 under four development scenarios: natural development, ecological protection, cultivated land protection, and engineering safety. The results indicated a gradual expansion of ecological land, while cultivated land and general ecological land exhibited distinct development trajectories. Spatially, carbon storage showed a pronounced west–high/east–low pattern, with high-density zones concentrated in the northwestern mountainous and hilly terrain under key ecological land and low-density zones prevailing in the eastern plains, urban built-up areas, and the Danjiangkou Reservoir surface. During the observation period, carbon gain patches proliferated across the northwestern mountains and reservoir-adjacent ecological restoration belts, whereas carbon loss areas gradually expanded from scattered hotspots toward the eastern plains and river valleys. Regional carbon sink initially decreased slightly but subsequently showed a gradual increase. Ecological land functioned as the primary carbon sink, whereas cultivated land contributed the largest share of carbon emissions. Across the simulated trajectories, the ecological conservation scenario resulted in the highest carbon sequestration, followed by the cultivated land protection scenario, while the natural development and engineering safety scenarios showed relatively limited carbon sequestration effects. Under the four scenarios, the projected 2030 spatial layout preserved the prevailing west–high/east–low configuration but diverged notably in the distribution of gains and losses: the ecological protection scenario generated connected carbon gain patches over the northwestern mountains and reservoir restoration belts, the cropland protection scenario triggered dispersed carbon loss zones around urban peripheries and river valley agricultural belts, and the engineering safety scenario maintained the most stable spatial pattern. GeoDetector analysis identified slope, elevation, and NDVI as the principal factors associated with spatial variations in carbon sink. Furthermore, the interaction between slope and NDVI produced the highest explanatory power, indicating that their combined influence on the phenomenon was significantly stronger than the effect of either factor alone. Based on these findings, adjustments to the land-use plan are proposed to enhance carbon sequestration and strengthen ecological security in the Henan section of the South-to-North Water Diversion Project.

Solar interfacial evaporation (SIE) provides a low-carbon route for seawater desalination, but its nonequilibrium phase-change interface may create an overlooked pathway for microplastic transfer from seawater to condensate. To address this water-quality risk, a low-cost and regenerable photothermal interface was constructed by modifying natural sea sand with polyaniline (PANI@SS). The PANI coating enhanced broadband solar absorption and promoted interfacial water activation, achieving an evaporation rate of 2.20 kg·m−2·h−1. Adsorption kinetics, thermodynamics, spectroscopic characterization, and molecular dynamics simulations showed that PANI converted the weak physical retention of pristine sea sand into stable interfacial anchoring. The strengthened retention counteracted phase-change-driven microplastic transport and confined particles at the evaporation interface. Reversible protonation/deprotonation of PANI enabled pH-regulated interfacial affinity, supporting facile regeneration and sustained antifouling performance. PANI@SS showed effective retention for seven representative microplastics with different structures and polarities, indicating broad applicability. In a 30-day outdoor desalination test using natural seawater collected from the Yellow, Yangtze, and Pearl River estuaries, cumulative freshwater production exceeded 220 kg·m−2, while the desalinated water met drinking-water guideline limits for major ions. Evaporation performance, microplastic retention, and material structure remained stable after repeated evaporation–regeneration cycles. This study reveals the competition between phase-change transport and interfacial retention as a key mechanism governing microplastic migration and product-water safety in SIE, and provides a practical design strategy for efficient, durable, and regenerable solar desalination.

Refuse-derived fuel (RDF) presents a viable strategy to concurrently address the challenges of municipal solid waste management and the need for alternative energy. In this context, the present review systematically synthesizes recent advances in RDF preparation, combustion behavior, and efficient utilization technologies. The study examines the full chain of RDF production—including waste selection, mechanical/optical/magnetic sorting, granulation, briquetting, and chemical modification—highlighting how pretreatment technologies influence fuel homogeneity, calorific value, and emissions. The thermochemical conversion characteristics of RDF are systematically analyzed, covering the mechanism differences among slow pyrolysis, fast pyrolysis, flash pyrolysis, pyrolysis mechanisms, catalytic pyrolysis, fragmentation behavior, volatile release patterns, and kinetic modeling using Arrhenius and model-free isoconversional methods (e.g., FWO). Special attention is given to co-firing and high-efficiency combustion technologies, including ultra-supercritical boilers, circulating fluidized beds, and rotary kilns, where fuel quality, ash fusion behavior, slagging, bed agglomeration, and particulate emissions determine operational compatibility. Integrating recent findings, this review identifies the key technical bottlenecks—feedstock variability, chlorine/sulfur release, heavy-metal contaminants, ash-related issues, and the need for standardized RDF quality control. Emerging solutions such as AI-assisted sorting, catalytic upgrading, optimized co-firing strategies, and advanced thermal conversion systems (oxy-fuel, chemical looping, supercritical steam cycles) are discussed within the broader context of carbon reduction and circular economy transitions. Overall, RDF represents a scalable, flexible, and high-value waste-to-energy pathway, and the review provides insights into future research directions, system optimization, and policy frameworks required to support its industrial deployment.

The adsorption behavior of perfluorooctanoic acid (PFOA) in soils is critical for understanding its environmental transport. However, the effects and mechanisms of humic substances (HS) as an organic soil amendment on PFOA adsorption in soils are still unclear. This study investigated the interactions between HS, particularly humic acid (HA) and fulvic acid (FA), PFOA and soil during the PFOA adsorption process in soil environment. The adsorption capacities of PFOA followed the order: Soil > Soil + HA > Soil + FA > HA > FA. HS, with their negative charges, hindered PFOA adsorption by occupying surface adsorption sites. Fluorescence quenching experiments confirmed HS-PFOA complex formation. PFOA preferentially bound to humic acid-like and fulvic acid-like substances. The primary adsorption sites in both soil and HS were –OH and C–O–C groups. Although HS formed complexes with PFOA, they reduced the overall adsorption capacity in soil. HA provided more hydrophobic interaction sites for PFOA than FA, and FA, with a higher negative charge, exerted stronger electrostatic repulsion, leading to a more significant reduction in PFOA adsorption. This study highlights the role of different HS in PFOA soil adsorption and offers insights for soil remediation and risk assessment of PFOA.