Reviews in Environmental Science and Bio/Technology最新文献

Rhizoremediation exploits interactions among plant roots, root-associated microorganisms and soil processes to transform, remove or immobilize contaminants. Yet biological activity under controlled conditions often does not translate into reproducible performance in heterogeneous field soils. This critical narrative review examines this translation problem and organizes the literature around four broad, interacting bottleneck domains: contaminant accessibility, biological capacity, environmental expression and operational feasibility. These domains provide an evidence-informed conceptual structure rather than a quantitative classification of failure frequency. We further distinguish chemical change, risk reduction and ecological recovery as related but non-equivalent outcomes, showing why greater biomass, microbial abundance, enzyme activity or contaminant availability cannot alone establish remediation success. On this basis, we propose a conceptual decision framework linking site diagnosis to candidate intervention selection, realistic pilot validation and multidimensional monitoring. Intervention choice is treated as conditional: biostimulation may be appropriate where relevant indigenous functions are constrained; bioaugmentation may be considered where realized functional capacity remains insufficient; amendments may be appropriate where accessibility, soil chemistry, root-zone habitat or toxicity limits performance; and combined approaches may be required where constraints co-occur or shift over time. Future tools, including multi-omics, synthetic communities, predictive modelling and genetic engineering, should be judged by whether they reduce uncertainty and improve robustness under realistic conditions. Field-reliable rhizoremediation therefore depends on reproducible, durable and site-appropriate performance rather than biological potential alone.

Nitrous oxide (N₂O) emissions from croplands are a distinct environmental challenge because N₂O is both a potent greenhouse gas and a major contributor to stratospheric ozone depletion. Emissions arise largely from agricultural nitrogen (N) inputs and microbially mediated nitrification and denitrification as N pools are transformed under fluctuating soil oxygen and moisture conditions. Yet N inputs are central to maintaining yield stability, ensuring an adequate food protein supply, and sustaining farm profitability. Therefore, mitigation strategies that rely predominantly on reducing N use are difficult to scale without compromising agricultural productivity. When expressed as chlorofluorocarbon-11–equivalent ozone-depleting emissions, N₂O (179.0 kt yr⁻¹) exceeds the combined emissions of legacy ozone-depleting substances and transitional hydrochlorofluorocarbons (145.7 kt yr⁻¹), strengthening the case for prioritizing agricultural N₂O within climate and ozone-protection frameworks. In this review, we synthesize current understanding of nitrification- and denitrification-derived pathways of N₂O formation and the biological sink of N₂O reduction to dinitrogen (N₂), emphasizing how fertilizer-driven shifts in N pools interact with soil to regulate pathway dominance and the N₂O:N₂ product ratio. We then place these mechanisms in the context of 21st-century fertilizer-use trajectories and rising atmospheric N₂O and summarize the stratospheric reactions that couple agricultural N₂O to ozone loss. Building on these mechanistic foundations, we evaluate direct nitrification-targeted mitigation by contrasting synthetic nitrification inhibitors with emerging biological nitrification-inhibition traits and their potential integration into the cropping system. Finally, we highlight how recent Conference of the Parties negotiations and the 2024 Global N₂O Assessment are elevating N₂O as a priority on the climate and ozone protection agenda. We argue that durable scaling of mitigation will require outcome-based quantification, including models and measurement strategies that deliver credible seasonal-to-annual estimates with transparent uncertainty, so that management changes translate into verifiable N₂O reductions and eligible incentives.

Per- and polyfluoroalkyl substances (PFAS) have emerged as persistent contaminants of significant concern due to widespread use. The vadose zone plays a critical role in PFAS fate and transport, as a temporary reservoir, trapping PFAS, and a conduit to groundwater. This paper reviews the current status and future challenges in detecting, predicting fate, and remediating PFAS in the vadose zone. The paper first evaluates detection technologies, highlighting sensitivity and reliability across environmental matrices and remaining challenges (i.e., emerging PFAS, the lack of real-time in-situ monitoring). PFAS fate and transport are then examined within the vadose zone, where interfacial processes and environmental conditions significantly affect PFAS mobility. Critical gaps in transport modeling are identified, emphasizing the need for long-term field data and system-specific studies. Furthermore, current and emerging technologies (e.g., novel materials) for remediation are assessed for their potential to enhance PFAS removal. Treatment effectiveness varies based on PFAS chain length, environmental conditions, treatment duration, and scalability. Challenges in translating laboratory success to field applications, maintaining long-term performance, managing treatment residuals, and meeting regulatory targets are also discussed. The novelty of this review is grounded in deciphering PFAS interfacial dynamics in the vadose zone and the potential of machine learning and deep learning to overcome knowledge gaps and challenges caused by the complex interfacial interactions. Bridging pore-scale retention and field-scale predictability can help optimize detection, transport modeling, and remediation. This framework redefines the unsaturated subsurface as a contaminant reservoir, providing a predictive roadmap for managing this persistent groundwater contamination source.

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemical compounds used widely in industrial and consumer products. The exceptional stability of terminal perfluoroalkyl acids (PFAAs)—including perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS)—stems from strong carbon–fluorine bonds, which render these compounds highly resistant to environmental degradation. Polyfluoroalkyl precursors, by contrast, retain at least one non-fluorinated carbon and are capable of undergoing stepwise environmental transformation, ultimately yielding the same persistent PFAAs as terminal products. This longevity has led to widespread contamination of surface waters, groundwater, soils, and drinking water globally. In 2024, the U.S. EPA established enforceable standards for six PFAS, with limits as low as 4 ng/L for PFOA and PFOS, reflecting health concerns at trace concentrations. Legacy compounds continue to persist despite regulatory phase-outs. Short-chain alternatives and polyfluoroalkyl precursors transform into stable perfluoroalkyl acids, sustaining environmental burdens. We examine PFAS chemistry, environmental fate, and management technologies across the product life cycle-from manufacturing to disposal. Transport through interconnected environmental compartments receives particular attention, with soils and sediments functioning as long-term secondary sources. Toxicity in aquatic organisms and human health implications are reviewed, with emphasis on chronic low-dose exposure and mixture effects. Analytical approaches span targeted methods, suspect screening, and fluorine mass-balance techniques. Management technologies are evaluated with a distinction between separation and destruction processes, including verification requirements. Knowledge gaps in emerging PFAS, precursor transformation, and analytical harmonization point toward the need for improved monitoring and risk-reduction strategies. Key conclusions of this synthesis are: (a) soils and sediments act as long-term PFAS reservoirs introducing multi-year lags between emission controls and exposure reductions; (b) targeted analytical methods capture only a fraction of total organofluorine burden, requiring tiered frameworks combining TOP assay and fluorine mass-balance metrics; (c) human exposure is inherently mixture-driven and demands compound-group rather than substance-by-substance risk assessment; and (d) treatment technologies must demonstrate verified destruction rather than mere phase transfer of PFAS.

Malting and brewery wastewaters present environmental and economic challenges to the brewing industry due to their high organic loads and variable nutrient content, with chemical oxygen demand (COD) values ranging from 328 to 4500 mg/L and 910 to 8926 mg/L, respectively. Conventional treatment methods are limited by high energy consumption, sludge generation, and most importantly, a lack of resource valorisation. This review critically examines the role of extracellular polymeric substances (EPS) as key functional enablers in microalgae-based treatment of these effluents. Microalgal EPS enhance pollutant removal through biosorption mechanisms, facilitate biomass harvesting via natural self-flocculation, and represent valuable bioproducts with applications in the food, pharmaceutical, and environmental sectors. Integrating these functions within a circular biorefinery framework offers a holistic strategy that shifts traditional linear treatment methods toward circular resource utilisation pathways. Key technical and economic barriers to implementation are also identified in this review, including process scale-up, low-energy EPS extraction, and market development for EPS products.

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The global coffee industry generates millions of tons of biomass residues annually, including pulp, husk, silverskin, and spent coffee grounds (SCG). These residues are often underutilized or discarded, despite being rich in bioactive compounds, dietary fiber, and carbonaceous materials. Their underutilization represents a missed opportunity for sustainable valorization and resource efficiency. This review synthesizes recent advances in chemical, biochemical, and thermochemical approaches for coffee residue valorization. Unlike prior reviews that typically address a single residue type or application domain, this work makes three integrative contributions: it covers the full spectrum of waste streams-pulp, husk, silverskin, and SCG-across the entire processing chain; it bridges agricultural valorization and nanotechnological/material-based applications within a unified evaluative framework; and it embeds these assessments within system-level considerations including cascading biorefinery design, life cycle assessment, techno-economic analysis, and digital optimization. Green extraction techniques, biotransformation processes, and advanced materials processing are critically evaluated across these dimensions. Coffee residues can be effectively converted into functional ingredients, biostimulants, bioplastics, and carbon-based nanomaterials, but the environmental and economic ranking of competing valorization routes is highly sensitive to feedstock moisture, transport logistics, product portfolio diversification, and grid carbon intensity. Cascading biorefinery models can achieve over 85% mass valorization, and the integration of AI-based optimization further enhances circular potential. This review underscores that advancing coffee residue valorization from laboratory promise to industrial reality requires not only process innovation but also standardized feedstock specifications, harmonized regulatory frameworks, and evidence-based policy incentives. Future research should prioritize closing the gap between single-product demonstrations and integrated, multi-product biorefinery systems.

Anaerobic digestion (AD) of crop straw provides a promising route for converting abundant agricultural residues into methane and other value-added products. However, straw AD remains constrained by lignocellulosic recalcitrance, slow hydrolysis, uneven substrate accessibility, and the instability of multitrophic microbial interactions. This review synthesizes recent advances in straw AD by linking the major digestion stages, including hydrolysis, acidogenesis, acetogenesis, and methanogenesis, with the functional genes, microbial guilds, syntrophic interactions, and operational drivers that regulate process performance. Particular attention is given to straw-specific barriers, such as cellulose-hemicellulose-lignin associations, hydroxycinnamate cross-linking, particle heterogeneity, and limited enzyme–substrate contact. Multi-omics approaches are discussed as tools for connecting microbial composition, functional potential, gene expression, enzyme activity, and metabolic phenotypes, while their limitations in causal inference, data comparability, and functional validation are also examined. The review further highlights how omics-derived indicators, including hydrolytic enzyme modules, volatile fatty acid profiles, methanogenic markers, syntrophic partners, and stress-related functional signals, may support reactor diagnosis and operational control. Future progress in straw AD will depend on integrating genome-resolved multi-omics, targeted activity assays, perturbation experiments, and function-first cultivation to develop more reliable biomarkers, bioaugmentation strategies, and synthetic microbial communities for stable and predictable bioconversion.

Climate change is intensifying environmental constraints in arid and semi-arid regions, where agricultural systems face recurrent drought, soil degradation, salinity, nutrient depletion, and increasing biotic pressures. While perennial crops are increasingly recognized for their role in stabilizing agroecosystems, the mechanistic integration of plant functional traits, microbial symbioses, and agroecological practices remains insufficiently addressed, particularly in Crassulacean Acid Metabolism (CAM) species. Opuntia ficus-indica, a widely cultivated CAM perennial, represents a relevant model for understanding plant resilience under water-limited conditions due to its high water-use efficiency and stress-adaptive traits. This review addresses this gap by synthesizing current knowledge through a structured framework encompassing: (i) functional traits of perennial and CAM plants, (ii) responses of O. ficus-indica to major abiotic and biotic stresses, (iii) agroecological practices for stress mitigation, and (iv) the role of plant growth-promoting rhizobacteria (PGPR) and arbuscular mycorrhizal fungi (AMF) in enhancing plant resilience. Mechanistically, agroecological practices such as intercropping, organic amendments, soil conservation, and optimized water management improve soil quality and resource availability, thereby supporting plant adaptive responses. In parallel, PGPR and AMF enhance stress tolerance through complementary processes, including improved nutrient acquisition, modulation of phytohormonal balance, osmotic adjustment, ion homeostasis, and activation of antioxidant defense systems. By integrating plant functional ecology, microbial interactions, and agroecological strategies, this review proposes a conceptual framework that positions O. ficus-indica as a model CAM system for improving stress resilience. Such integrative approaches are particularly relevant for optimizing the performance and sustainability of CAM crops under multiple environmental constraints in arid and semi-arid regions.

Ammonia (NH₃) emissions have become an increasingly significant issue in the livestock industry due to their negative impact on the environment and the emphasis on sustainable dairy production. A key principle in achieving source-oriented NH₃ emission reduction is limiting urease activity in urine puddles. Optimizing floor management has been considered to be effective in limiting urease activity, thereby mitigating NH₃ emissions. Given these considerations, this review synthesizes current knowledge by addressing four objectives: (1) describing the physicochemical mechanisms of NH₃ release and its relationship to urease activity; (2) mapping the primary distribution of urease in dairy houses; (3) evaluating factors influencing urease activity, alongside methods to quantify their contributions; and (4) identifying effective floor management strategies to reduce urease activity and NH₃ emissions. Urease, a ubiquitous microbial enzyme in nature, is primarily found in faeces and on floor surfaces within dairy houses. Based on Michaelis–Menten kinetics, the urease activity within a urine puddle is primarily governed by three key factors: maximum reaction rate, Michaelis constant, and the urea concentration in the puddle, which relate to the practical floor management strategies. Effective reduction of its activity in urine puddles requires integrated strategies combining optimized floor design, targeted disinfectant application, compatible manure handling practices, and scheduled cleaning protocols. A single-factor approach is insufficient to limit urease activity and achieve source-oriented NH₃ emission reduction. This review provides a scientifically grounded and practical framework for implementing ammonia reduction strategies by diminishing urease activity in dairy housing systems.

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Accounting for the third-largest share of global nitrous oxide (N₂O) emissions, paddy fields are a major source of this potent greenhouse gas, with emissions driven primarily by denitrification. N₂O emissions may contribute to both ozone layer depletion and global warming, and pose substantial threats to public health and agricultural sustainability. Therefore, elucidating the microbial communities and their associated N₂O emission pathways in paddy ecosystems is an urgent scientific priority. This manuscript identified the denitrifying microbial taxa responsible for N₂O emissions across multiple taxonomic levels, from phylum to genus. Critically, while key genera such as Pseudomonas, Bacillus, and Paracoccus within the phyla Pseudomonadota and Actinomycetota are highlighted, these represented only the confirmed denitrifying members within their respective phyla. The underlying mechanisms of nitrogen loss mediated by the denitrifying microorganisms in paddy soils, along with the factors influencing nitrate removal and N₂O flux, were carefully elucidated. A comparative analysis of both N₂O emissions and denitrifying microbial community distribution in paddy fields across different countries and regions was presented. The relationships between specific microbial groups and N₂O emission patterns were discussed. Based on these findings, this paper proposed targeted mitigation strategies aimed at suppressing the growth and activity of denitrifying microorganisms, including optimizing fertilizer application methods and improving irrigation technologies, to reduce N₂O emissions. Future research directions in this field are also outlined. Collectively, this review intends to provide references for mitigating climate change and promoting sustainable agricultural development.

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