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401. 题目: Effects of long-term biochar application on soil hydraulic properties and interconnected mechanisms of water, nutrients, and carbon
文章编号: N26081103
期刊: Soil and Tillage Research
作者: Chao Gao, Lili Guo, Meng Tian, Yan Tian, Di Li, Shike Zhang, Zhibo Zhong, Shuai He, Guobing Wang
更新时间: 2026-08-11
摘要: The long-term integration of biochar into soil matrices remains a critical frontier in sustainable agriculture. To investigate the effects of biochar on the soil water characteristic curve (SWCC), soil nutrient-enzyme activity, and carbon fractionation, we conducted an 11-year field experiment. Three treatments were established: a control (CK), wood-derived biochar (WB) and coconut shell-derived biochar (CSB), each applied once at a rate of 3.015 kg m−2. The results showed that the two biochar types exerted complementary effects. CSB was most effective at improving soil structure: it alleviated soil compaction, reducing average bulk density by 13.75%, from 1.60 g cm−3 in CK to 1.38 g cm−3 (p < 0.05), this structural alteration changed the soil water curve, driving saturated water content (θS) up by 17.17%, from 0.3843 cm3 cm−3 to 0.4503 cm3 cm−3. WB was most effective at soil water and carbon retention, showing the greatest water retention at low potentials (highest residual water content and highest retention at the permanent wilting point, 1.5 MPa) and the highest soil organic carbon (SOC, 20.11 g kg−1). Both biochar markedly increased SOC, and reduced dissolved organic carbon (DOC) with the largest decline of 46.57% under WB (from 43.31 mg kg−1 in CK to 23.14 mg kg−1) and a 37.68% reduction under CSB (to 27.00 mg kg−1; p < 0.05), consistent with enhanced adsorption and reduced leaching of labile carbon within biochar micropores. Concurrently, this physical protection promoted a 28.93% accumulation of particulate organic carbon (POC), from 3.05 g kg−1 in CK to 3.93 g kg−1 in CSB, which may serve as a nucleating agent for soil aggregation. Although aggregate stability was not directly measured in this study, the observed accumulation of POC could contribute to the enhanced soil hydraulic properties. This improved hydro-physical microenvironment, in conjunction with the accumulation of physically protected organic carbon, synergistically stimulated key extracellular enzyme activities. These results indicate that both biochar act along complementary pathways: CSB driving structural and porosity gains, and WB enhancing moisture conservation and carbon retention, suggesting a potential positive feedback among physical, hydraulic, carbon, and biological processes.

402. 题目: Limited remineralization of Arctic permafrost-derived organic carbon in nearshore marine sediments
文章编号: N26081102
期刊: Nature Geoscience
作者: Manuel Ruben, Bingbing Wei, Anabel von Jackowski, Jens Hefter, Torben Gentz, Florence Schubotz, Heidi Taubner, Bo Liu, Michael Fritz, Anna Irrgang, Walter Geibert, Maarten Boersma, Gabriel A Juma, Silla Thomsen, Gesine Mollenhauer
更新时间: 2026-08-11
摘要: Rapid Arctic warming causes thawing and erosion of coastal permafrost, releasing organic carbon into the Arctic Ocean. Although much of this organic carbon is deposited in marine sediments, the extent to which it is remineralized and re-enters the active carbon cycle remains uncertain. Here we examine the fate of permafrost-derived organic carbon in the nearshore sediments of Qikiqtaruk, Canada. Analysis of dual carbon isotopes revealed that nearshore sedimentary organic carbon originated predominantly from eroded ancient permafrost deposits, but the remineralization end-product, dissolved inorganic carbon, diffusing back out of the sediment was younger and predominantly of marine origin. We estimate that <10% of land-derived Pleistocene permafrost organic carbon is respired after redeposition in marine sediments. Our findings indicate that despite substantial Pleistocene permafrost organic carbon accumulation in marine sediments due to permafrost thaw and coastal erosion, much of it remains buried, potentially limiting its immediate contribution to atmospheric carbon. However, given the high reactivity of permafrost organic carbon entering the ocean, a reactive subfraction may remain in the water column or was degraded prior to redeposition in the analysed sediments, highlighting the need for more comprehensive assessments of permafrost organic carbon degradation and its inclusion into Earth system models.

403. 题目: Increasingly diverse allochthonous input promote recalcitrance and homogenization of dissolved organic matter along the land-sea continuum
文章编号: N26081101
期刊: Journal of Hydrology
作者: Liyin Qu, Mingxing Ren, Dezhong Wang, Ting Wang, Randy A Dahlgren, Shengyao Sun, Jixin Chen, Xuwen Fang, Penghui Li, Weidong Guo
更新时间: 2026-08-11
摘要: Estuaries are receiving increasingly diverse allochthonous dissolved organic matter (DOM) with variable reactivities as global change intensifies, yet the ultimate fate of this mixed-source DOM along the dynamic land-sea interface remains poorly constrained. Herein, we investigated spatiotemporal variability in DOM molecular composition along the Zhangjiang river-estuary-bay continuum, characterizing eight anthropogenic and wetland DOM endmembers. Dissolved organic carbon (DOC) and DOM chemodiversity increased along the continuum and peaked in the upper estuary across all hydrological periods. DOC addition from urban sewage, aquaculture effluent and mangrove creek runoff was comparable to riverine DOC input during the intermediate and dry seasons, whereas submarine groundwater discharge only contributed to elevated DOM chemodiversity. A thermodynamically-related biotransformation model further revealed that allochthonous aliphatics were stepwise transformed into recalcitrant islands of stability (IOS) molecules during seaward transport through successive dehydrogenation, denitrogenation and oxidation, with reactions shifting from thermodynamically favorable to increasingly constrained conditions. Nonetheless, over 70% of in situ produced RDOM molecules showed net removal along the estuary via adsorption/flocculation and sedimentation, potentially contributing to estuarine carbon burial. Ultimately, 26–56% of DOM molecules from different endmembers were removed during export, highlighting the estuary as a hotspot of carbon transformation and burial through efficient processing of diverse allochthonous DOM. These processes ultimately promoted homogenization of estuarine DOM pools. These findings provide mechanistic insights for predicting/constraining the carbon budgets of estuaries under ongoing environmental change.

404. 题目: Lacustrine groundwater discharge as a key role for DOM dynamics during non–freezing and freezing seasons: Evidence from fluorescence and radon isotopic model
文章编号: N26081017
期刊: Journal of Environmental Management
作者: Yuanzhen Zhao, Lijuan Hu, Shen Qu, Chuntao Zhao, Xu Yang, Heyang Sun, Zhongli Wang, Xiaomin Liu, Ruihong Yu
更新时间: 2026-08-10
摘要: The relationship between lacustrine groundwater discharge (LGD) and dissolved organic matter (DOM) dynamics remains insufficiently understood, particularly during the freezing season. In this study, the spatial and seasonal variability and controlling factors of DOM in surface water and groundwater were investigated in a representative ice–covered lake basin (Ulansuhai Lake, China). Specifically, the effects of LGD on DOM sources and transport during non–freezing and freezing seasons were examined using fluorescence excitation–emission matrix spectroscopy coupled with parallel factor analysis (EEM–PARAFAC) and a 222Rn mass balance model (RMBM). During the non–freezing season, DOM was primarily composed of humic–like components (C1–C3), whereas during the freezing season, in addition to humic–like components (C1–C3), protein–like component (C4) was also identified. Quantitative source apportionment indicated that effluent (mean: 39%), soil (mean: 27%), fertilizers (mean: 20%), and plants (mean: 14%) were the dominant DOM sources. During the non–freezing season, LGD was relatively weak (mean LGD rate: 5.12 mm/d), and canal water served as the primary recharge source for both groundwater and lake water; consequently, allochthonous humic–like substances (components C1–C3) dominated the DOM pool. In contrast, during the freezing season, LGD intensified markedly (mean LGD rate: 17.49 mm/d), becoming the sole recharge source for the lake and amplifying the relative contribution of protein–like DOM (C4). Moreover, hydrological conditions and vegetation cover further regulated DOM dynamics by modulating LGD processes. Overall, this study highlights the crucial role of LGD in governing DOM dynamics and demonstrates the effectiveness of integrating optical techniques with isotopic mass balance modelling to elucidate biogeochemical processes under seasonally variable environmental conditions.

405. 题目: Synergistic piezo-photocatalytic activation of PMS by a water hyacinth–derived biochar/BiOCl catalyst for efficient ofloxacin degradation
文章编号: N26081016
期刊: Journal of Environmental Chemical Engineering
作者: Liangliang Chang, Zhen Wu, Hucheng Shu, Meilan Li, Bingcheng Bao, Wei Gong, Jinyi Guo, Baoyue Cao
更新时间: 2026-08-10
摘要: In this study, a novel piezo-photocatalytic material (BC/BiOCl) was successfully constructed by integrating water hyacinth-derived biochar (BC) with BiOCl nanosheets via a solvothermal method to efficiently activate peroxymonosulfate (PMS) for ofloxacin degradation. Under combined simulated light, ultrasonic vibration, and PMS, the 0.3% BC/BiOCl catalyst completely degraded ofloxacin within 24 min, achieving a rate constant of 0.419 min⁻¹ , which is 10.3 times higher than the sum of the two individual PMS-assisted systems. This enhancement is mainly attributed to BC incorporation, which strengthens the piezoelectric response and narrows the bandgap, thereby greatly improving visible-light absorption. Furthermore, experimental characterization of reactive species confirms the formation of an efficient oxidative network comprising h⁺, ·OH, ¹O₂, and SO₄⁻·, with SO₄⁻· appearing only upon PMS activation. Computational simulations further reveal that the BC/BiOCl heterojunction exhibits stronger adsorption affinity (–1.18 eV) and electron transfer capacity (0.459 e) toward PMS, facilitating O–O bond cleavage. Overall, the BC/BiOCl catalyst, through the synergistic combination of piezo-photocatalysis and PMS activation, offers a promising strategy for efficient antibiotic removal from water. To the best of our knowledge, this is the first study to integrate water hyacinth-derived biochar with BiOCl in a piezo-photocatalytic PMS activation system.

406. 题目: Acorn review: Biochar and its applications in US forestry
文章编号: N26081015
期刊: Forest Ecology and Management
作者: Gaurav Dhungel, Justin Baker, Jesse D Henderson, Rachel Cook
更新时间: 2026-08-10
摘要: Biochar derived from woody feedstocks is typically high in carbon, low in ash, and relatively low in nutrients compared with agricultural biochar, making it especially suitable for long-term carbon storage. Current evidence indicates that key functional properties for forestry applications include biochar yield, fixed carbon, pH, nutrient content, and porosity. Across studies, there is broad agreement that these properties are shaped by both feedstock and production conditions, particularly pyrolysis temperature and residence time. Yield and fixed carbon appear to be driven mainly by pyrolysis conditions, whereas pH, nutrient content, and porosity are more strongly linked to feedstock, though still influenced by processing temperature. At the same time, disagreement remains over how consistently wood-based biochar improves tree growth and productivity in forest systems. Reported outcomes range from positive to neutral to negative, reflecting differences in site conditions, application method and rate, and the interaction of biochar traits with forest soil ecosystems. Taken together, the literature suggests that biochar performance is highly context dependent and that benefits are most likely when biochar properties are matched to target species, site conditions, and the time horizon over which responses are evaluated. Overall, woodbased biochar should be viewed as a value-added use of low-value woody biomass rather than a universal solution. Its long-term role in forestry will depend on better alignment between biochar properties and site-specific management needs, expansion of end uses beyond soil amendment, improved production and distribution economics, and stronger policy support to facilitate broader adoption.

407. 题目: Simultaneous adsorption and removal of copper and chlortetracycline hydrochloride in the wastewater using the bridge effect of BC-Cu-CTC with grape waste-based biochar: Synergistic effect and mechanism analysis
文章编号: N26081014
期刊: Environmental Research
作者: Xinping Yang, Yanrong Cai, Xuechun Yu, Le Shi, Decheng Yang, Xiaoxiao Wang, Qiong Wang
更新时间: 2026-08-10
摘要: The combined pollution of heavy metals and antibiotics continues to threaten the safety of water bodies. Adsorption is an effective approach for removing the combined pollution of metals and antibiotics. Low-cost grape stalk biochar (SBC) and grape leaf biochar (LBC) were prepared through direct pyrolysis of grape waste. In the binary system (20 mg/L Cu2++10 mg/L CTC), the adsorption capacities of SBC for Cu2+ and CTC were 57.46 and 23.54 mg/g, respectively, while those of LBC were 56.71 and 20.82 mg/g, respectively. Compared with single adsorption, the removal rate of Cu2+ increased by 16.49% and 25.36% for SBC and LBC, respectively, the removal rates of CTC increased 26.22% and 41.03% for SBC and LBC, respectively. The adsorption removal process of Cu2+ and CTC followed Pseudo-Second-Order kinetics (PSO), primarily involved chemical adsorption. The adsorption isotherms could be described using a multi-isotherm model, indicating that the removal of Cu2+ and CTC involved multiple mechanisms. In addition to pore filling and electrostatic attraction, the adsorption of Cu2+ was primarily attributed to ion exchange and complexation, whereas the adsorption of CTC was mainly due to hydrogen bonding and π-π electron donor-acceptor (EDA) interactions. Density functional theory (DFT) calculations indicated that after the adsorption of Cu2+, the electron cloud density on the surface of biochar decreased, and CTC transitions from an electron acceptor to an electron donor, confirming that Cu2+ was a bridging molecule in the reaction. The results from the adsorption energy and HOMO-LUMO energy gap indicated that coexistence enhanced the adsorption energy and reduced the energy gap, regulating electronic interactions and achieving a synergistic adsorption effect. These findings provided theoretical basis and data support for the synergistic adsorption and immobilization of heavy metals and antibiotics.

408. 题目: Integrating source stabilization to ecological exposure: A new framework to reassess sludge biochar potential toxic elements risk driven by pyrolysis temperature
文章编号: N26081013
期刊: Ecotoxicology and Environmental Safety
作者: Minyan Wang, Jiamin Qi, Jialin Han, Chaochu Fang, Shunyu Yin, Jiaqi Li, Haohao Bian, Ming Hung Wong, Jin Zhang
更新时间: 2026-08-10
摘要: Pyrolysis is a promising strategy for sewage sludge valorization, yet potential toxic elements (PTEs) limit the safe application of sludge-derived biochar (SBC). Conventional assessments rely on source-based indicators (e.g., BCR sequential extraction method, the risk assessment code), assuming that higher pyrolysis temperatures improve PTE stability and reduce risk. However, this assumption lacks validation in real soil–plant systems. Here, the behavior of Cr, Ni, Pb, and Zn was tracked across SBCs produced at 400, 600, and 800 °C using oxidative aging, soil incubation (60% vs. 100% water-holding capacity), and pot experiments. High-temperature SBCs enhanced Cr and Pb stabilization, but plant uptake revealed metal-specific trade-offs: Ni accumulation increased under SBC800, while Zn peaked under SBC400. Soil moisture strongly modulated Ni and Zn bioavailability, and SBCs disturbed microbial communities and enzyme activity. We developed SEIR—a source-stabilization-to-ecological-exposure integrated risk assessment framework—to quantify source reactivation, soil mobilization, plant exposure, and process hazard. SEIR demonstrates that no universal “optimal” temperature exists. Instead, safe SBC use depends on PTE identity and site-specific water conditions. This exposure-oriented framework enables scenario-specific temperature selection, advancing risk assessment from material stabilization toward system-level ecological safety.

409. 题目: Cross-scale cascade effects of landscape patterns and soil geochemistry on soil organic carbon stability along an urban-rural gradient
文章编号: N26081012
期刊: Catena
作者: Xiangyang Cui, Jiong Wu, Jing Lu, Li Ma
更新时间: 2026-08-10
摘要: Urbanization affects soil organic carbon (SOC) dynamics, yet how macro-scale landscape configuration interacts with micro-scale edaphic properties to mediate SOC stability remains unclear. Along an urban-rural gradient in Shanghai, China, we investigated SOC, its physical fractions, particulate organic carbon (POC) and mineral-associated organic carbon (MAOC), and microbial necromass carbon (MNC). SOC and its fractions decreased from the urban core to the suburbs; within the built-up area, urbanization-induced SOC accrual was driven primarily by labile POC rather than stable MAOC, indicating a shift in carbon quality. Variation partitioning and structural equation modeling revealed a clear ranking in the relative importance of controls, with soil physicochemical properties exerting the strongest total effect, followed by microbial community traits, landscape patterns, and finally the urbanization gradient. Nitrogen and microbial biomass carbon were the primary drivers for absolute carbon accrual. The core transformation pathway “POC → microbial community → MNC → MAOC” validated the microbial carbon pump mechanism in urban soils. While soil chemical properties—the co-occurring high pH and inorganic carbon from urban infrastructure development debris—negatively controlled this conversion, overriding nitrogen benefits. Notably, while landscape metrics contributed negligibly to bulk SOC and POC variation, they independently explained 12.0% of the variance in MNC, far exceeding their effects on other pools. We term this counteracting mechanism the ‘urban geochemical syndrome’. These findings demonstrate that urban landscape fragmentation and geochemical disturbance jointly constrain long-term SOC stabilization through a cross-scale cascade, offering insights for integrating landscape planning with soil microbial management to enhance urban carbon sequestration.

410. 题目: Enhanced biological desilication by Bacillus mucilaginosus mutant: Multi-omics insights into extracellular polymeric substance overproduction and metabolic adaptations
文章编号: N26081011
期刊: Bioresource Technology
作者: Mengqi Liu, Bo Li, Feiyan Tan, Peng Li, Edwin Cheung, Yijun Cao, Yun Liu
更新时间: 2026-08-10
摘要: Recovering scandium from silicate-rich tailings remains a major challenge due to refractory mineral matrices. Although biological desilication using microbial secretomes offers an eco-friendly solution, its industrial application is limited by the poor understanding of the intracellular metabolic programs that govern high-efficiency desilication. Here, an N-methyl-N’-nitro-N-nitrosoguanidine (NTG)-induced Bacillus mucilaginosus mutant, BM3, was evaluated using integrated whole-genome sequencing, transcriptomics, non-targeted metabolomics and mineral-interface measurements. BM3 achieved a 1.7-fold increase in desilication rate and subsequent chemical leaching of the bio-pretreated tailings substantially elevated scandium extraction from 21% (untreated) and 38% (wild-type-pretreated) to 53%. Spectroscopic analyses indicated that this modified secretome acted as a reactive interface, preferentially eroding recalcitrant pyroxene phases via carboxyl, amino, and hydroxyl ligand coordination. Multi-omics integration suggested that a coordinated metabolic reprogramming, including changes in phenylalanine metabolism, purine metabolism, and folate one-carbon metabolism, may underpin this phenotype. Overall, these findings reveal that the enhanced desilication by BM3 is associated with coordinated metabolic reprogramming and a more reactive EPS-mineral interface, providing an effective biological pretreatment for disrupting silicate matrices and improving scandium recovery from refractory tailings.

411. 题目: Molten salt-templated synthesis of Fe-N5 sites on ramie-derived porous biochar for enhancing singlet oxygen generation and antibiotic degradation
文章编号: N26081010
期刊: Bioresource Technology
作者: Chenxi Huang, Dong Li, Yutong Zhang, Meifang Li, Xinjiang Hu, Chao Huang, Xiaofei Tan, Jiaqin Deng, Xi Hu, Hui Wang
更新时间: 2026-08-10
摘要: The Fe-N5 single-atom catalyst supported on porous carbon (Fe(S)-N-RBC) was fabricated from ramie fibers via molten salt-assisted pyrolysis. This method created a polar environment, yielding high-density Fe single atoms (4.5 wt%) and reconstructed pore structure. The Fe(S)-N-RBC/peroxydisulfate (PDS) system demonstrated efficient degradation of sulfamethoxazole (SMX) across an extensive pH range (3–9) and under high salinity, with excellent stability in continuous-flow reactors. Besides, it also exhibited excellent removal activity for diverse classes of antibiotics, confirming that this system had strong potential for practical application. Experimental results and density functional theory calculations revealed that molten salt-assisted pyrolysis modulated the coordination configuration of Fe-Nx sites and enhanced the electronic interaction between Fe-Nx and PDS, thus facilitated the PDS adsorption and lowered the energy barrier for generating singlet oxygen, which identified as the dominant reactive species. The reduced ecotoxicity of the degradation byproducts was confirmed by ecological structure activity relationship predictive modeling (ECOSAR) and phytotoxicity bioassays using Pisum sativum seedlings. This study provides key insights into an enhanced non-radical pathway facilitated by tailored Fe-N5 sites, offering a versatile molten-salt method for engineering single-atom catalysts for wastewater purification via advanced oxidation processes.

412. 题目: Waste salt-assisted pyrolysis of antibiotic fermentation residue for biochar production and hexavalent chromium reduction mechanism
文章编号: N26081009
期刊: Bioresource Technology
作者: Yuan Bai, Boxuan Wang, Xin Zhang, Zhihua Chen, Kai Jiang, Dapeng Wu
更新时间: 2026-08-10
摘要: The accumulation of antibiotic fermentation residue (AFR) and pharmaceutical waste salt (WS) poses a severe disposal challenge. Herein, a WS-assisted co-pyrolysis strategy is proposed to convert these hazardous waste streams into an active material for hexavalent chromium (Cr(VI)) reduction. During pretreatment, the intrinsic osmotic stress of WS disrupts microbial cells in AFR, thereby promoting deep dehydration. The subsequent thermal process effectively degrades residual antibiotics and antibiotic resistance genes. During co-pyrolysis, the inherent NaCl in WS acts as a mineral-phase regulator. The salt matrix promotes pore development in the carbon matrix, forming a hierarchical pore architecture. Concurrently, the salt matrix converts calcium-rich components into Ca5(PO4)3OH. These Ca5(PO4)3OH domains enrich CrO42- near Fe-containing redox sites, where Fe-mediated electron transfer drives the aqueous reduction of Cr(VI) to Cr(III). The synthesized composite achieves more than 90% reduction of low-concentration Cr(VI). Economic evaluation confirms the financial feasibility of this integrated protocol when avoided hazardous-waste disposal costs are considered. This integrated upcycling strategy mitigates pharmaceutical solid waste while producing functional biochar for environmental remediation.

413. 题目: Maize residue components dictate soil organic carbon allocation and microbial C use: Contrasting impacts modulated by soil fertility
文章编号: N26081008
期刊: Applied Soil Ecology
作者: Mengmeng Wang, Jiubo Pei, Shunguo Liu, Sidi Wang, Siyin Wang, Yao Zhang, Jiahui Shi, Jingkuan Wang
更新时间: 2026-08-10
摘要: Soil organic carbon (SOC) critically regulates global carbon cycling, serving as a keystone indicator of soil fertility and ecosystem sustainability. While maize residue incorporation enhances SOC accrual by stimulating microbial activity and nutrient cycling, the divergent impacts of residue components (roots, stems, leaves) on SOC transformation and microbial carbon utilization under varying soil fertility regimes remain poorly quantified. Using a 540-day in-situ field incubation experiment with 13C-labeled maize residues in brown earth (low vs. high fertility), we elucidated the component-specific contributions to active SOC pools and microbial metabolic partitioning. Key findings revealed distinct residue-driven SOC allocation patterns: the average proportion of residue-C mineralized as CO2 was significantly higher in low fertility soils (root: 2.81%; stem: 3.00%; leaf: 2.49%) than in high fertility soils (root: 2.28%; stem: 1.73%; leaf: 1.40%), indicating greater mineralization under nutrient-poor conditions. Conversely, incorporation into microbial biomass carbon was enhanced in high fertility soils, particularly for leaf residues (6.36%) compared to low fertility soils (3.62%), suggesting more efficient microbial anabolism. For SOC pools, leaf-derived carbon exhibited the highest conversion to dissolved organic carbon (up to 3.21%), whereas root and stem residues preferentially contributed to particulate organic carbon formation (up to 28.03% and 25.24%). Fertility status further modulated these dynamics: low fertility soils showed greater dissolved organic carbon accumulation during rapid decomposition, while high fertility soils enhanced particulate organic carbon stabilization across all residue types. Microbial metabolic strategies diverged significantly according to residue type and incubation stage. During the first 20 days, root residues yielded higher PLFA-C to MBC ratios than leaf residues (9.25% vs. 7.26% in low fertility soil; 8.67% vs. 3.30% in high fertility soil). In contrast, after 60 days of incubation, stem and leaf residues exhibited higher ratios than root residues. Notably, the ratios recorded after 60 days were consistently lower than those measured during the initial 20-day period. This temporal decline indicates a metabolic shift: during early decomposition, assimilated carbon was preferentially directed toward structural PLFA synthesis and cellular maintenance, whereas at later stages, carbon allocation transitioned toward biomass accrual. These quantitative patterns reveal distinct residue-driven soil organic carbon allocation pathways governed by tissue-specific substrate chemistry; low fertility soils amplify catabolic processing while high fertility soils favor anabolic sequestration, underscoring the interactive regulation of SOC dynamics by residue type and edaphic nutrient status. Collectively, our findings suggest that targeted incorporation of leaf residues in high-fertility agroecosystems represents a synergistic strategy to enhance carbon storage and mitigate greenhouse gas emissions.

414. 题目: Plastic fragments impair soil organic carbon persistence through reshaping microbial metabolism and decreasing plant carbon supply in dryland ecosystems
文章编号: N26081007
期刊: Agriculture, Ecosystems & Environment
作者: Meng-Ying Li, Wei Wang, Yudi M Lozano, Jia-Yao Yang, Yue Ma, Xiao-Bin Xiong, Shuang-Jin Huang, Muhammad Ashraf, Jian-Ming Li, Yun-Li Xiao, Zheng-Guo Cheng, You-Cai Xiong
更新时间: 2026-08-10
摘要: Plastic fragments (PFs) arising from the widespread use and incomplete recovery of plastic-film mulch are increasingly prevalent in dryland agroecosystems; however, their effects on soil organic carbon (SOC) persistence remain poorly understood. Herein, polyethylene (PE, recalcitrant) and polylactic acid (PLA, biodegradable) fragments were applied to 0–20-cm soil layer at three concentration levels, i.e. 102.3, 303.1, and 503.9 kg ha−1. By combining 13C tracing, extracellular enzyme stoichiometry, and metagenomic analyses, the influences of PFs on plant-derived C allocation, microbial functional traits, and SOC persistence were investigated. Elevated PF concentrations substantially suppressed the retention of plant-derived C within shoots, roots and bulk soils, with retention losses ranging from 11.8% to 31.5%. This impaired C translocation into SOC pools was evidenced by pronounced decreases in plant-derived C stored in mineral-associated organic carbon (MAOC) and total particulate organic carbon (POC) stocks. Conversely, total bulk MAOC and SOC stocks exhibited no significant alterations. Activities of C-, nitrogen (N)-, and phosphorus (P)-acquiring hydrolases decreased markedly with rising PF concentrations, with the most pronounced declines (8.1%-18.9%) under PE exposure. At the maximal PF concentration, PE induced a 20.5% significant reduction in microbial biomass C. Meanwhile, bacterial necromass C exhibited distinct losses of up to 9.6% and 9.1% for the PE and PLA treatments, respectively. Both polymers significantly reduced soil mean weight diameter by 4.2%-13.2%. Metagenomes revealed significant community reassembly and a shift toward catabolism, with PLA enriching CAZy (carbohydrate-active enzymes) depolymerases and central C metabolism genes. Yet, they reduced glycosyltransferases linked to cell-wall and exopolysaccharide biosynthesis. Structural equation modeling revealed depleted root-derived C input as the dominant driver associating altered microbial functioning and weakened aggregation to inhibited microbial necromass formation and retarded MAOC accrual. These findings improve predictions of SOC persistence amid plastic contamination and define functional molecular targets for developing effective mitigation measures.

415. 题目: Alleviation of microbial metabolic limitation promoting SOC stocks in agricultural soil aggregates
文章编号: N26081006
期刊: Agriculture, Ecosystems & Environment
作者: Yiting Li, Hao Liao, Xiuli Hao, Qiaoyun Huang, Wenli Chen
更新时间: 2026-08-10
摘要: Soil stores the largest terrestrial organic carbon pools, largely regulated by microbial metabolisms. Fertilizers inputs critically influence the soil nutrient availability, elemental stoichiometry of substrates, leading to alteration in soil microbial metabolic limitation. However, our understanding of how microbial metabolic status responded to different fertilization and its consequences in soil organic carbon (SOC) sequestration, particularly at aggregate scale, remains limited. Here, our study used an ecoenzymatic stoichiometry model to quantify microbial metabolic limitations in agricultural soil aggregates under different fertilization regimes and linked this limitation to microbial community structure and SOC contents. Our results showed that straw returning effectively alleviated microbial C and P limitation in macroaggregates (250–2000 μm) and microaggregates (53–250 μm), further contributing to SOC sequestration. In contrast, microbial metabolic limitations were greater in silt + clay (< 53 μm) and less affected by the fertilization regimes. The alleviation of microbial metabolic limitations in aggregates was attributed to enhance fungi/bacteria ratio, microbial biomass and bacterial oligotrophs/copiotrophs ratio. Our findings provide new insights into aggregate SOC cycle via microbial metabolic limitation, demonstrating that straw application promotes SOC sequestration by relieving microbial metabolic limitations. This study highlights the important roles of soil aggregation mediating agricultural soil carbon cycling and improving agroecosystem functioning.

416. 题目: Exogenous dissolved organic matter redirects humic carbon fate at mineral interfaces through pre-contact molecular conditioning
文章编号: N26081005
期刊: Water Research
作者: Yu Li, Guangxu Mi, Jianghao Cheng, Meiling Zhang, Ying Liu, Shuang Ai, Fan Yang, Kui Cheng
更新时间: 2026-08-10
摘要: Mineral-associated organic carbon (MAOC) formation is commonly interpreted from the moment organic matter contacts mineral surfaces, emphasizing mineral reactivity, molecular functional groups, or adsorption strength. However, in soils receiving continuous organic inputs, humic precursors may first coexist with exogenous dissolved organic matter (DOM) in pore water and thin water films before mineral contact. Whether this upstream liquid-phase interaction reorganizes humic matter and redirects its subsequent mineral-interface fate remains poorly understood. Here, we introduce the concept of a pre-contact molecular conditioning and examine whether biochar-derived dissolved organic matter (BDOM) reorganizes the humic acid (HA) precursor state before contact with goethite (GOE), montmorillonite (MON), and a goethite-montmorillonite composite (MGA). FT-ICR MS spectrometry revealed that mineral-free co-incubation with BDOM generated a distinct HA-BDOM molecular pool rather than a simple addition of the two endmembers, producing 951 newly detected formulas, increasing O/C (17.97%) and nominal oxidation state of carbon (NOSC, 18.46%), and decreasing double-bond equivalent (DBE, 20.26%), modified aromaticity index (AImod, 15.76%), and (DBE−O)/C (55.41%). This pre-contact conditioning weakened the bulk affinity of HA for Fe-bearing minerals (53.45% on GOE, 63.12% on MGA). The lower first-contact retention did not imply a weaker contribution to MAOC formation. At the MGA interface, pristine HA underwent extensive molecular reorganization and released numerous transformation products, whereas HA-BDOM retained a larger proportion of its original formulas and preserved a broader molecular mass range. After remobilization, the HA-BDOM-derived pool showed a 44.2% greater capacity to associate with fresh MGA than the HA-derived pool. These results distinguish immediate mineral retention from the longer-term capacity of organic matter to undergo renewed association. The principal effect of BDOM was therefore not simply to alter adsorption strength, but to preserve molecular continuity across successive mineral-contact events. MAOC formation should thus be viewed as a sequential process whose outcome is partly determined by molecular conditioning in solution before mineral contact.

417. 题目: Reactive organic matter destabilizes Fe-mediated phosphorus retention through Fe–S–P decoupling in lake sediments
文章编号: N26081004
期刊: Water Research
作者: Yaping Liu, Lixin Jiao, Jia He, Liansheng He, Di Song, Jing Liu, Yaru Feng
更新时间: 2026-08-10
摘要: Despite reductions in external inputs, internal phosphorus (P) release from sediments remains a key barrier to lake recovery. Conventional mineral-centered frameworks inadequately account for the fundamental role of reactive organic matter in driving redox-mediated shifts in sediment P stability. We analyzed a 180-year sediment record from a subtropical plateau lake and quantified a critical threshold that controls phosphorus stability. When the ratio of reactive dissolved organic carbon (rDOC) to reactive Fe exceeds 8.04 (95% CI: 4.42∼10.53), abrupt destabilization of the Fe-mediated P sink is observed, indicating that electron donor supply has exceeded the Fe(III) buffering capacity of the sediment. Below this threshold, the geochemical and isotopic record is consistent with dissimilatory Fe reduction as the predominant anaerobic terminal electron-accepting process, sustaining a redox-sensitive Fe-bound P sink. Above this threshold, DGT profiles, stable isotope records (δ15N, δ13C), and SEM-EDS data collectively indicate progressive sulfide accumulation and geochemical conditions consistent with competition between sulfide and phosphate for dissolved Fe2+ at the sediment–water interface, suggesting weakening of Fe-mediated P retention. This transition coincides with a shift in organic matter sources from terrestrial to sewage- and algae-derived inputs, as recorded by rising δ15N and shifting δ13C values. Anthropogenic nitrogen enrichment (δ15N > 2.5‰) further amplifies this process. These findings identify the rDOC:reactive Fe ratio as a quantitative early-warning indicator for Fe-mediated P sink failure, and demonstrate that reactive organic matter loading history, rather than mineral composition alone, is a critical determinant of sediment P stability in anthropogenically stressed lakes.

418. 题目: High carbon burial fluxes in lakes do not equate to stable carbon sinks: Evidence from typical large river-connected lake systems
文章编号: N26081003
期刊: Water Research
作者: Zheng Huang, Shilan Wang, Zhongwu Li, Fengwei Ran, Ming Chen, Xiaodong Nie, Xinyu Ling, Chengyu Zhong
更新时间: 2026-08-10
摘要: Lakes play a pivotal role in the global carbon cycle and climate change mitigation by sequestering carbon. However, under combined human and climate pressures, it remains uncertain whether increased organic carbon burial flux (OCBF) necessarily corresponds to stable carbon sequestration. Here, we utilized MAOC% as the key indicator of organic carbon pool stability (OCPS), complemented by grain size and isotopic signatures from high resolution sedimentary records, to investigate the mechanisms underlying the decoupling between OCBF and OCPS in Dongting Lake. Results showed that OCBF and OCPS responded nonlinearly to sedimentary transitions, explaining 72% and 46% of their respective variance (p < 0.001). In East Dongting, OCBF peaked at 350.30 ± 253.51 g C m⁻² yr⁻¹, primarily driven by eutrophication enhanced autotrophic production. However, the rapid burial of labile organic matter likely overwhelmed the available capacity for stable mineral association, contributing to a marked decline in the proportion of mineral associated organic carbon (MAOC%). This imbalance ultimately weakened the OCPS. In contrast, West Dongting maintained a consistently high MAOC% (94.63%) due to sustained inputs of fine minerals from upstream channel scouring. This mineral supply promoted persistent organic mineral associations, resulting in continuously enhanced OCPS despite a relatively lower burial flux (250.60 ± 61.00 g C m⁻² yr⁻¹). These findings provide robust evidence that high OCBF does not necessarily indicate a stable carbon sink. We therefore emphasize that a multidimensional assessment framework integrating carbon flux and stability is essential for developing spatially differentiated and effective lake carbon management strategies.

419. 题目: Distinct and Synergistic Roles of Bacteria, Fungi, and Extracellular Polymeric Substances in Soil Aggregation
文章编号: N26081002
期刊: Soil Biology and Biochemistry
作者: Yujia Luo, Marta.F.S. Cardoso, Ruben Halfwerk, Valentina Sechi, Wolfgang Wanek, Cees J N Buisman
更新时间: 2026-08-10
摘要: Microbial extracellular polymeric substances (EPS) are key chemical bonding compounds in soil, yet their capacity to form and stabilize soil aggregates independently of microbial processes remains unclear. Here, we used a controlled microcosm experiment with selective biocide treatments to disentangle the roles of EPS and soil microbiota in aggregation. We found that bacterial-dominated soil produced substantial polysaccharide-rich EPS, which facilitated microaggregate formation. However, despite elevated EPS-polysaccharide concentrations, aggregates lacking fungal cellular integrity and activity rapidly disintegrated upon wetting. This suggests that fungal hyphal networks are critical for macroaggregate stability, likely through a combination of physical enmeshment and continuous production of protein-rich EPS. While EPS represent promising soil management tools, their effectiveness critically depends on the presence of active, interacting microbial communities.

420. 题目: Organic carbon accumulation alleviates microbial metabolic limitations to enhance soil multifunctionality in coastal saline soils
文章编号: N26081001
期刊: Soil and Tillage Research
作者: Xiangxiang Wang, Jiejun Xi, Guanjun Li, Qianru Wang, Xuefei Li, Timo Vesala, Jianping Chen, Tida Ge, Zhenke Zhu
更新时间: 2026-08-10
摘要: Soil multifunctionality (SMF) underpins ecosystem stability and productivity in coastal saline landscapes, yet the microbial mechanisms linking soil organic carbon (SOC) accumulation to functional recovery remain unclear. We assessed soil quality and SMF along a long-term succession gradient from Spartina alterniflora marshes to reclaimed croplands—including upland and paddy systems—across 186 sites in eastern China. Soil physicochemical properties, microbial biomass, and extracellular enzyme activities were quantified, and microbial metabolic limitations were evaluated using ecoenzymatic stoichiometry. A composite soil quality index (SQI) integrated key functional indicators. SOC and nutrient availability increased by 34%–47% along the succession gradient, whereas salinity and microbial carbon (C) and phosphorus (P) limitations declined by 7.6%–14.2%, 9.1%–12.8%, and 4.0%–5.2%, respectively. Both SQI and SMF peaked in reclaimed paddy soils. Microbial C and P limitations were negatively associated with SOC, SQI, and SMF, indicating alleviation of metabolic limitation during ecosystem development. Random forest analysis revealed a shift in SMF regulation: from nutrient and enzyme-driven under low salinity to SOC and microbial biomass-driven under high salinity. Mechanistically, SOC accumulation mitigated microbial metabolic limitations, promoting a transition from survival-oriented maintenance to growth-focused resource allocation, enhancing enzyme production and coupling of C, N, and P cycles. These results identify microbial metabolic limitation as a central mechanism linking SOC to SMF and provide a framework for predicting soil functional recovery in saline ecosystems.