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241. 题目: Heteroaggregation-driven regulation of levofloxacin adsorption by nano-biochar–goethite complexes in aquatic environments
文章编号: N26082507
期刊: Environmental Science: Processes & Impacts
作者: Fengfeng Ma, Yani Cai, Qing Li, Ranxi Li, Wengang Wang
更新时间: 2026-08-25
摘要: The heteroaggregation of naturally occurring substances is crucial for the transportation, transformation, and fate of biochar nanoparticles (BNPs). This study systematically investigates the heteroaggregation behavior between BNPs and goethite (GT), with particular emphasis on their colloidal stability, interaction energetics, and the resulting effects on levofloxacin (LEV) adsorption. BNPs exhibited the highest colloidal stability at pH 7.5. In mixed systems, the coexistence of BNPs and GT enhanced the dispersion of GT particles while simultaneously diminishing the stability of BNPs. The maximum energy barriers (Φmax) for homo- and hetero-aggregation followed the order GT–GT (−10.4 × 10−18 J) < BNPs–GT (2.85 × 10−18 J) < BNPs–BNPs (6.4 × 10−17 J), indicating that GT tends to undergo homopolymerization prior to subsequent heteroaggregation with BNPs. Both Na+ and Ca2+ promoted BNP–GT heteroaggregation, with Ca2+ exhibiting a markedly stronger effect as evidenced by the lower critical coagulation concentration (CCC). When BNP concentration remained below the critical threshold (40 mg TOC per L), BNP effectively enhanced GT dispersion. However, above this threshold, extensive heteroaggregation occurred, forming large and compact heteroaggregates. Heteropolymer formation partially shielded the surface functional groups of BNPs, thereby restricting LEV access to available adsorption sites. Nonetheless, at elevated LEV concentrations, LEV molecules were able to penetrate the heteropolymer matrix or induce structural rearrangements, enabling access to internal sites and enhancing overall adsorption capacity. Interestingly, at low BNP concentrations, the BNP–GT mixture improved LEV removal by inhibiting GT agglomeration and exposing additional adsorption sites. In contrast, at high BNP concentrations, the formation of large heteroaggregates occluded active sites and diminished LEV adsorption efficiency. Overall, this study provides mechanistic insights into BNP–mineral interactions in natural waters and elucidates their implications for the environmental transport and fate of antibiotics. These findings advance the current understanding of nanoparticle–mineral heteroaggregation processes and offer important guidance for predicting contaminant mobility in aquatic environments.

242. 题目: Changes in Molecular Chemistry of Stream Organic Matter and Low Molecular Weight Disinfection Byproduct Precursors Following Initial Post-Fire Rainstorms
文章编号: N26082506
期刊: ACS ES&T Water
作者: William Bahureksa, Charles C Rhoades, Timothy S Fegel, Holly K Roth, Kenneth Hickenbottom, Jacob P VanderRoest, David Hanigan, Amy M McKenna, Michael J Wilkins, Thomas Borch
更新时间: 2026-08-25
摘要: Forested ecosystems are vulnerable to wildfires which have short- and long-term effects on downstream water quality, including changes to dissolved organic carbon (DOC) transport and disinfection byproduct (DBP) formation downstream, which can be exacerbated by high-intensity rainstorms. To evaluate short-term changes to streamwater composition and characteristics, we sampled three streams feeding into the Cache la Poudre River within the perimeter of the 2020 Cameron Peak Fire before, during, and after the first postfire summer storm season. Streams were distinguished by the proportion of their upstream watershed that burned at moderate to high severity (<25%, 25–50%, or >50%). DOC concentration and turbidity demonstrated storm-driven responses that were greatest in the 25–50% burn area stream. Nitrogen-containing species were enriched in streams during the storm and poststorm periods, depending on burn area. Chlorination experiments measured low molecular weight (C1 – C2) DBPs, where streams from subcatchments with more extensive burns were greater in DOC and DBPs formed across all events. However, DOC released during the storms formed less DBPs on a DOC-normalized basis in all streams. These results demonstrate that DBP formation following wildfire disturbance is primarily driven by storm-mediated increases in DOC loading rather than enrichment in highly reactive pyrogenic material.

243. 题目: Machine-Learning-Assisted Auto-Fluorescence Cell-Sorting-Based Fast Differentiation and Quantification of Extracellular Polymeric Substances in the Microalgae and Bacteria Consortium
文章编号: N26082505
期刊: Environmental Science & Technology
作者: Libo Xia, Xiaocai Cui, Tian Ren, Ting Ran, Lingfang Huang, Beibei Wu, Peng Cai, Yun Zhou
更新时间: 2026-08-25
摘要: Extracellular polymeric substances (EPS) are crucial in microalgae-bacteria consortia (MBC)-based wastewater treatment. Revealing the roles of EPS depends on reliable and accurate differentiation, extraction, and quantification of EPS from microalgae and bacteria in the MBC. Autofluorescence-based cell sorting (AFCS) coupled with thermal extraction can achieve the above goals, but it is time-consuming and costly, and invoves unignorable EPS loss (0.4–3.9%) during cell sorting. In this work, the raw data of microalgae (3.42 ± 0.14 mg/g TSS – 52.38 ± 0.47 mg/g TSS) and bacteria (2.95 ± 0.17 mg/g TSS – 48.94 ± 0.21 mg/g TSS) EPS from a series of MBC are obtained using AFCS with thermal extraction. Machine learning regression models are applied for microalgae and bacteria identification, and EPS concentration simulation and prediction. Results showed that, based on the total EPS concentrations and the fluorescence scattering characteristics (obtained from flow cytometry) of the MBC before and after heating, machine learning regression models enabled accurate prediction of EPS concentrations from microalgae (k-Nearest Neighbors, R2 = 0.975, P < 0.001) and bacteria (eXtreme Gradient Boosting, R2 = 0.953, P < 0.001) in the MBC, without cell sorting or EPS loss. This study provides an innovative method for rapid and accurate quantification of total EPS in microalgae and bacteria without requiring physical separation of the MBC, thereby laying a crucial foundation for in-depth analysis of EPS-based interaction mechanisms and functional regulation of microalgae and bacteria within the MBC during wastewater treatment.

244. 题目: Microplastic-Derived Dissolved Organic Matter: Environmental Chemistry and Ecological Consequences
文章编号: N26082504
期刊: Environmental Science & Technology
作者: Jing Wang, Peng Li, Weimin Zhu, Jialiang Gu, Zihan Fan, Jun Ma, Nanqi Ren, Defeng Xing
更新时间: 2026-08-25
摘要: Microplastics (MPs) are widely recognized as particulate hazards, yet environmental aging releases a time-evolving pool of MP-derived dissolved organic matter (MP-DOM) that engages in photochemical and redox reactions. This work provides a critical overview of the aging mechanisms of MPs and the release characteristics of MP-DOM, with emphasis on its molecular properties and the intrinsic and extrinsic factors driving DOM release. Particular attention is given to the strong polymer dependence of MP-DOM, as different plastic classes can generate dissolved mixtures with distinct release kinetics, chemical profiles, and environmental reactivities. Insights into the unstable characteristics of MP-DOM are translated into measurable physicochemical reactions by evaluating its photochemical reactivity and interactions with natural minerals. Importantly, high methodological heterogeneity in experimental protocols hampers reliable comparisons across studies, underscoring the need for standardized leaching procedures in MP-DOM quantification and characterization. The role of MP-DOM in influencing the behavior of environmental pollutants, such as organic contaminants, metals, and antibiotic resistance genes, is critically assessed, particularly its contribution to disinfection byproduct formation, an ongoing concern in water quality management. Recent advances in understanding the ecological and biogeochemical impacts of MP-DOM are synthesized, highlighting its effects on cellular toxicity, microbial responses, and disruptions in element cycling and greenhouse gas emissions. Future directions include standardized aging protocols, rapid source attribution methods, and transferable models for predicting MP-DOM fate and ecological consequences under multistressor conditions. This review provides an updated synthesis of MP-DOM by linking its environmental behavior to ecological fate, advancing our understanding of the long-term ecological impacts and toxicity of plastics.

245. 题目: Tracing Combustion Regime Shifts through Char and Soot Black Carbon Records in Beibu Gulf Sediment Cores: Burial Flux Controls and Carbon Storage Assessment
文章编号: N26082503
期刊: Environmental Science & Technology
作者: Liwei Mo, Ruijie Zhang, Li Zhang, Jing Guo, Jingyu Wang, Zhehong Ji, Pan Wei, Quanfa Ye, Yinghui Wang, Kefu Yu
更新时间: 2026-08-25
摘要: Black carbon (BC) in marine sediments provides a unique archive of combustion history and a reservoir for long-term carbon storage. However, the distinct roles of char BC (CBC) and soot BC (SBC) in combustion-source tracing and carbon-cycle assessment remain poorly resolved in marginal seas. Here, we analyze four sediment cores from the Beibu Gulf, South China Sea, using benzene poly(carboxylic acid) (BPCA) and chemothermal oxidation at 375 °C (CTO-375) methods to resolve subtype-specific BC records. CBC accounted for 52–57% of the estimated total BC burial across all settings, consistent with sustained biomass-burning contributions. SBC exhibited higher spatiotemporal variability and sensitivity to fossil fuel expansion, particularly near industrial zones. Estimated BC burial fluxes varied spatially, largely reflecting differences in representative sedimentation rates rather than BC content. Notably, nearshore sites exhibited higher burial despite lower BC content. Centennial-scale profiles revealed that SBC effectively traced regional transitions from biomass to fossil fuel combustion, while CBC preserved the long-term fire legacy. These findings highlight the complementary roles of CBC and SBC in reconstructing combustion histories and assessing BC burial in marginal seas. Burial of biomass-derived BC can contribute to net atmospheric CO2 sequestration, whereas fossil-derived BC burial represents the transfer of fossil carbon into long-term sedimentary storage.

246. 题目: Transformation of Dissolved Organic Matter by Aqueous Fe(IV) under Acidic Conditions: Bulk-to-Molecular Insights into Reaction Kinetics and Mechanisms
文章编号: N26082502
期刊: Environmental Science & Technology
作者: Zhen Wang, Wenbo Liu, Yunho Lee, Jin Jiang
更新时间: 2026-08-25
摘要: Aqueous Fe(IV) has emerged as a significant nonradical oxidant in iron-based oxidative water treatment, yet its reaction kinetics and mechanisms with dissolved organic matter (DOM) remain largely unexplored. Herein, second-order rate constants (k) for Fe(IV) reactions with DOM and DOM-relevant model compounds were determined under acidic conditions using a competition kinetics method performed on self-assembled quenched-flow apparatuses. At pH 3.0, k for 15 DOM isolates ranged from (2.1 ± 0.2) × 104 MC–1 s–1 to (11.6 ± 0.9) × 104 MC–1 s–1 and correlated strongly with the electron-donating capacity of DOM. Similarly, k for nine para-substituted phenolic compounds correlated linearly with the Hammett constant σ+, EHOMO, and vertical ionization potential, supporting Fe(IV) selectivity toward electron-rich substrates. Across pH 1.0–3.5, k for DOM increased monotonically from the 104 to 105 MC–1 s–1 scale. In contrast, k for 11 model compounds representing major DOM moieties spanned 101–107 M–1 s–1 and exhibited moiety-specific pH dependences, indicating that individual DOM components contribute differently to overall Fe(IV)-DOM reactivity. Fluorescence spectroscopy revealed broad-spectrum oxidation of DOM fluorophores, whereas high-resolution mass spectrometry showed that Fe(IV) preferentially transformed unsaturated moieties, oxidized nitrogen/sulfur-containing functionalities, and fragmented moderate-molecular-weight molecules. These findings provide a bulk-to-molecular kinetic and mechanistic basis for predicting Fe(IV) fate in DOM-containing waters and optimizing Fe(IV)-based advanced oxidation processes.

247. 题目: A Kinetic-Molecular Framework for Resolving Electron-Donating Moieties in Natural and Effluent Organic Matter
文章编号: N26082501
期刊: Environmental Science & Technology
作者: Quan Gao, Yanheng Pan, Qinglong Fu, Shuangshuang Cheng, Xin Yang
更新时间: 2026-08-25
摘要: The redox activity of dissolved organic matter (DOM) plays a critical role in natural and engineering aquatic systems. Although phenolic moieties are typically recognized as the dominant electron-donating moieties (EDM) in naturally occurring DOM (NOM), the chemical nature and reactivity of EDM in wastewater-derived DOM (EfOM), remain poorly understood. In this study, a kinetic categorizing framework was developed for resolving the composition of EDM within DOM by using the second-order rate constants for the reactions of the radical cation of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•+) (kapp, ABTS•+) with DOM isolates and a suite of model electron-donating compounds. Our results reveal that NOM contains a larger fraction of rapidly reacting ABTS•+ reducible components with kapp, ABTS•+ > 1 × 103 M–1 s–1, accounting for more than 50% of the total EDM. In contrast, EDM in EfOM mainly consist of antioxidants with relatively low redox activity (kapp, ABTS•+ < 10 M–1 s–1), accounting for 70% of the total EDM. Combining kinetic categorization and Fourier transform ion cyclotron resonance mass spectrometry analysis, the results suggest that EDM in EfOM are associated with nitrogen- and/or sulfur-containing heteroatom compounds. This novel method has important implications for understanding the aquatic redox chemistry of DOM and developing source-adaptive water oxidative treatment strategies in engineering systems.

248. 题目: Black carbon emissions and climate impacts of cost-saving Arctic transit shipping through 2050
文章编号: N26082417
期刊: Nature Sustainability
作者: Wen Yi, Nikita Strelkovskii, Tingkun He, Weiwei Zhang, Xiaotong Wang, Elena Rovenskaya, Xueqing Wang, Yihang Gong, Zhenyu Luo, Kebin He, Huan Liu
更新时间: 2026-08-24
摘要: As climate change accelerates, emerging Arctic routes offer economic gains by shortening voyages but pose climate risks through black carbon deposition on snow and ice. Here we assess Arctic transit shipping at the global scale. Among 295 port pairs with reduced distance, only 249 achieve positive net economic benefits when accounting for fuel, transit, insurance, capital costs and turnover profits. By 2050, Arctic transit shipping could generate up to US$2.3 billion annually. Black carbon emissions are expected to reach 2,200 tons, with a regional maximum temperature response of 2.0–2.9 mK per US$1 billion of economic benefit. Rising fuel prices are expected to increase the economic attractiveness of Arctic transit shipping. Faster energy transitions could enable earlier decoupling of economic benefits from climate impacts, whereas slower transitions may require adjustments such as transit fees and insurance premiums to limit climate risks.

249. 题目: Plot‑Scale Assessment of Sewage Sludge and Biochar Effects on Soil Properties, Soil Erodibility, and Runoff in Contrasting Textural Soil
文章编号: N26082416
期刊: Water, Air, & Soil Pollution
作者: Shamsollah Ayoubi, Mitra Hajabedi, Mohammad Reza Mosaddeghi
更新时间: 2026-08-24
摘要: Population growth is expected to increase by 65% by 2050, placing additional pressure on soil and water resources, particularly in erosion-prone areas like Iran. This study addresses a gap in soil management by comparing the effects of raw sewage sludge and its biochar derivative on soil erodibility, hydraulic properties, and erosion dynamics. The comparison was conducted across two distinct soil textures: silty clay loam (SiCL) and sandy clay loam (SCL). A controlled plot-scale experiment, utilizing simulated rainfall at an intensity of 60 mm h⁻1, tested four amendment rates (0–2 wt. %). Key soil properties, including organic carbon, shear strength, and hydraulic conductivity, were measured, along with runoff and sediment yield. The results revealed that the soil texture affected the response to treatments. Biochar proved more effective than sludge in SCL, reducing soil loss by 47.72% at a 2% application rate. In contrast, sewage sludge was more effective in improving aggregate stability and hydraulic conductivity (Ks) in SiCL. Specifically, organic carbon increased by 56.77% with the addition of sludge in SiCL, which was strongly correlated with reduction in bulk density (r = − 0.73, p < 0.01) and runoff (r = − 0.65, p < 0.01). However, the hydrophobicity of biochar in SCL increased runoff, showing the trade-offs between the two treatments. Regression models revealed that soil organic matter (SOM) and Ks were the primary predictors of runoff (R2 = 0.62) and soil loss (R2 = 0.60). This study demonstrates that biochar is more effective in coarse-textured soils, while sewage sludge is more effective in fine-textured soils, providing new evidence for improving erosion mitigation practices and highlighting the need for soil-specific amendment strategies to protect agricultural resilience.

250. 题目: Soil organic carbon fraction mediated microbial community assembly along stand age and seasonal gradients in temperate poplar plantations
文章编号: N26082415
期刊: Plant and Soil
作者: Xiangrong Liu, Changjun Ding, Lingyu Hou, Qiwu Sun, Weixi Zhang, Wenxu Zhu, Xiaohua Su, Zhongyi Pang, Rusheng Peng, Yanlin Zhang, Zhengsai Yuan
更新时间: 2026-08-24
摘要: Background and Aims Despite harboring the largest forest carbon stocks, soil carbon persistence is mainly controlled by microbial regulators. However, there are large uncertainties about the mechanisms of microbial community ecology interaction with soil carbon speciation. We aimed to disentangle the links between microbial community assembly dynamics and soil carbon fraction responses across stand age and seasonal gradients. Methods In this study, we sampled soils from temperate populus (Populus euramevicana cv.‘I-214’) plantations of four different stand ages (3, 6, 10, and 13 years) for three seasons (spring, summer, and autumn), and applied integrated analyses including high-throughput sequencing, co-occurrence network construction, null and neutral modeling, and assessments of soil physicochemical properties to characterize microbial community assembly and its associations with soil carbon fractions. Results Stand age, season, and their interaction significantly affected soil organic carbon (SOC), easily oxidizable organic carbon (EOC), particulate organic carbon, mineral-associated organic carbon (MAOC), and recalcitrant organic carbon (ROC) (P < 0.001), whereas dissolved organic carbon (DOC) was not significantly affected. Stand development increased MAOC and ROC, while seasonal variation mainly altered labile organic carbon (OC) fractions. Bacterial community assembly was predominantly stochastic, with undominated processes accounting for significantly greater proportions in spring and summer than in autumn, and in 13-year-old stands than in 10-year-old stands. In contrast, sequence-based fungal assembly was predominantly deterministic across seasons and stand ages, but no pairwise differences in assembly-process proportions remained significant after Holm correction. The inferred balance between deterministic and stochastic fungal assembly was sensitive to phylogenetic representation. Bacterial β-nearest taxon index (βNTI) was significantly associated with soil pH, SOC, ROC, cellulase activity, and the C/P ratio, whereas fungal βNTI was not significantly related to the measured soil properties. Bacterial module 3 and fungal module 2 were key predictors of SOC fraction dynamics (P < 0.05). Microbial r-strategists were mainly associated with labile OC and DOC turnover, whereas K-strategists were linked to ROC and MAOC transformation and stabilization. Conclusion Overall, bacterial and fungal communities followed contrasting assembly pathways during poplar stand development, with significant seasonal shifts detected only for bacterial communities. Neither deterministic nor stochastic assembly should be regarded as universally preferable; rather, their ecological importance depends on microbial group, stand age, and season. These findings suggest that plantation management should maintain this context-dependent balance by avoiding intensive soil disturbance and abrupt changes in soil pH or nutrient stoichiometry, rather than assuming a uniformly optimal season or assembly pathway.

251. 题目: Modeling soil organic carbon dynamics under land-use and climate change scenarios using the RothC model in the Eastern Black Sea Region, Turkey
文章编号: N26082414
期刊: Journal of Soils and Sediments
作者: Necla Koralay
更新时间: 2026-08-24
摘要: Purpose This study aimed to evaluate the effects of land-use on soil organic carbon (SOC) dynamics and project future SOC changes under baseline, RCP4.5, and RCP8.5 climate scenarios in the Söğütlü Stream watershed in the Eastern Black Sea Region, Türkiye. Methods A total of 123 soil sampling points were established at 1500 m intervals across forest, pasture, and agricultural lands. SOC stocks were determined from 0 to 30 cm soil samples, and their spatial distribution was mapped using Inverse Distance Weighting (IDW) interpolation in a Geographic Information System (GIS). Future SOC dynamics (2026–2050) were simulated using the RothC model under baseline, RCP4.5, and RCP8.5 climate scenarios. Differences among land-use systems were assessed using the Kruskal–Wallis test, following evaluation of data normality and homogeneity using the Shapiro–Wilk and Levene tests, respectively. Results The study revealed a consistent decline in SOC stocks across all land-use systems, with baseline stocks significantly higher in forest soils (89.83 ± 64.15 t C ha− 1) followed by pasture (81.64 ± 28.28 t C ha− 1) and agriculture (56.50 ± 37.83 t C ha− 1). RothC simulations indicated that climate change may accelerate these losses by 2050, particularly under the RCP8.5 scenario. Agricultural systems exhibited the highest vulnerability, showing nearly twice the SOC loss (40.1%) compared to the more resilient forest (20.6%) and pasture (22.6%) ecosystems, which demonstrated greater relative resistance to climatic pressures. Conclusion Land-use is a primary driver of soil carbon dynamics, with agricultural expansion significantly exacerbating soil degradation under changing climate conditions. By integrating field data with predictive modeling, this study provides a process-based approximation of SOC dynamics. These findings offer critical implications for sustainable land management, highlighting that targeted conservation strategies are needed to mitigate carbon depletion, protect vulnerable agriculture, and enhance the inherent resilience of forest and pasture ecosystems.

252. 题目: Photochemical interactions between iron minerals and dissolved organic matter
文章编号: N26082413
期刊: Nature Reviews Earth & Environment
作者: Jingjing Wang (王晶晶), Hailiang Dong (董海良), Georges Ona-Nguema, Juan Liu (刘娟), Qiaohui Fan (范桥辉), Ping Li (李平), Zhao Huang (黄钊), Jingxiong Zhou (周京雄), Fan Chen (陈帆), Xiaoquan Liu (刘小权), Yanru Liang (梁艳茹), Yuheng Wang (王宇恒)
更新时间: 2026-08-24
摘要: Interactions between iron minerals and dissolved organic matter (DOM) are ubiquitous across environmental systems, but the global effects of photochemical synergies between DOM and iron minerals in surface environments remain to be comprehensively elucidated. Contrary to the assumption that minerals primarily stabilize organic matter, iron minerals also control the release, conversion and mineralization of associated organic carbon through dissolution, phase evolution and photo-oxidation. Concurrently, DOM modulates the photoreduction, transformation and reactivity of iron minerals via light-mediated electron transfer and photochemically generated reactive oxygen species. These mineral–organic interactions are shaped by environmental variables and molecular characteristics that exert a marked influence on the mobility, speciation and transformation of associated contaminants, particularly at dynamic environmental interfaces. This Review focuses on the reactivity, vulnerability and spatial heterogeneity of iron and carbon pools in response to solar radiation and provides an update on how light shapes the coupling of iron and carbon cycles in terrestrial and aquatic surface systems. Field observations integrated with laboratory experiments, and advanced analytical techniques could enable the photochemistry of iron minerals and DOM to provide a framework for improved understanding of the biogeochemical cycling of iron, carbon and contaminants, refining carbon budgets and informing sustainable remediation strategies.

253. 题目: Biochar facilitates the accumulation of organic matter within macroaggregates in paddy soil
文章编号: N26082412
期刊: Journal of Soils and Sediments
作者: Xinxin Jin, Yuetong Hou, Xiaojie Zhang, Tongxin Zhang, Yuehong Teng, Yongchao Pang, Na Yu, Hongtao Zou, Jun Meng, Jingkuan Wang
更新时间: 2026-08-24
摘要: Purpose Soil aggregates play a protective role in the accumulation of organic carbon (OC) and total nitrogen (TN). However, the mechanism by which biochar addition to paddy soil influences organic matter within soil aggregates remains poorly understood. Therefore, a better understanding of the effects of biochar addition on the fate of soil organic carbon fractions and the changes in their positions within soil aggregates is crucial for improving our predictions of carbon sequestration in paddy soil. Materials and methods In this study, we applied different rates (0.5%, 1%, 2%) of rice straw biochar into paddy soil in Northeast China to examine OC and TN in both total soil and aggregates. Results and discussion After one year of cultivation (the crop was rice), from an overall perspective, biochar addition increased the contents of particulate OC (POC) and organic nitrogen (PON). These increases being particularly noticeable after 360 d of cultivation, showing increases of 15% and 24% respectively compared to the no biochar control treatment (CK). Simultaneously, the biochar treatment increased POC and PON in > 0.25 mm-sized aggregates by 3–16% and 15–28%, respectively compared to CK. The biochar application also significantly increased the water-soluble organic C and N (WSOC, WSON) concentrations. However, the effect of adding 2% biochar was less than lower addition levels. The aggregate contribution of SOC and TN to total soil was highest, followed by that of POC and PON, with the minimal contributions from WSOC and WSON. Conclusions This highlighted the actual pathway by which biochar application regimes enhance aggregate stability and increase SOC and TN. We found that the effects of biochar addition on organic carbon and nitrogen fractions show a strong temporal dependence, and the most significant differences are observed at the 360 - day incubation stage. Overall, the treatment with 0.5% and 1% biochar addition demonstrated the most excellent comprehensive performance.

254. 题目: Magnetically Recoverable Alhagi Maurorum-Derived Biochar as an Efficient Adsorbent for Carbamazepine 10,11-Epoxide (CBZ-E) Removal from Aqueous Solutions: Synthesis, Characterization, and Mechanistic Insights
文章编号: N26082411
期刊: Water, Air, & Soil Pollution
作者: Shahad A Raheem
更新时间: 2026-08-24
摘要: Carbamazepine-10,11-epoxide (CBZ-E) is a major metabolite of the anticonvulsant drug carbamazepine and is widely recognized as a persistent, mobile, and toxic contaminant in aquatic environments. This study aimed to develop a novel magnetic biochar from Alhagi Maurorum (AM-BC) for CBZ-E removal. AM-BC was chemically activated with KOH to increase surface area, promote the development of micro- and mesopores, and introduce -O functional groups. Consequent thermal activation resulted in enhanced structural stability. Magnetic biochar (Fe₃O₄/AM-BC) was prepared by co-precipitation using FeCl₃ and FeCl2. Characterization results confirmed the production of Fe₃O₄/AM-BC, which exhibited a saturation magnetization of 23.4 emu/g, a hierarchical porous structure with a surface area of 741.383 m2/g, and abundant functional groups. Adsorption of CBZ-E reached a removal efficiency of 96.35% at a pH of 6, Fe₃O₄/AM-BC dose of 0.5 g/L, CBZ-E concentration of 25 mg/L, and contact time of 120 min. The Freundlich isotherm model fitted the data well, with a higher R2 of 0.947, lower X2, and SSE, indicating a heterogeneous surface with a non-uniform distribution of sites and energies. The maximum adsorption capacity was 184.53 mg/g. PSO kinetic described CBZ-E adsorption, confirming a chemisorption process. IPD and thermodynamic studies indicated that adsorption occurred through various mechanisms, including pore filling, π–π interactions, hydrogen bonding, and surface complexation. The regeneration study confirmed significant reusability and structural stability of Fe₃O₄/AM-BC, with a slight reduction in efficiency after five cycles. In conclusion, Fe₃O₄/AM-BC has been verified as an effective adsorbent for the limited adsorption-based research on CBZ-E, shifting focus from the widely studied parent compound to its underexplored metabolite. As well as introducing a sustainable adsorbent system through the reuse and management of agricultural waste.

255. 题目: High performance of Fe(III)-modified maize stover biochar for adsorptive removal of sulfamethoxazole from aqueous solutions
文章编号: N26082410
期刊: Environmental Geochemistry and Health
作者: Nguyen Thi An Hang, Le Thi Duyen, Bui Thi Hang, Nguyen Thi Hoang Ha, Bui Thi Kim Anh, Nguyen Manh Khai, Nguyen Minh Viet
更新时间: 2026-08-24
摘要: The increasing occurrence of antibiotics in the aquatic environment and the associated risks of antibiotic resistance have raised interest in the development of effective remediation technologies. In this study, a magnetic biochar (MSB-Fe) was fabricated from maize stover through Fe(III) impregnation followed by pyrolysis for the adsorption of sulfamethoxazole (SMX) from aqueous solutions. The physicochemical properties, adsorption performance, mechanisms, and reusability of the adsorbent were systematically investigated. Characterization by SEM, BET, FTIR, XPS, and XRD confirmed that Fe modification coupled with pyrolysis significantly improved the surface area, pore structure, and surface chemistry of the biochar, resulting in a high maximum adsorption capacity of 183.19 mg/g, outperforming many lignocellulosic biochars. The adsorption process was well described by the Langmuir isotherm and Pseudo-second-order kinetic models and was found to be spontaneous and endothermic. Mechanistic study indicated that pore filling, hydrogen bonding, Fe-mediated surface complexation, and π–π EDA interactions synergistically governed SMX adsorption. Regeneration tests showed that although a mixture of 0.15 M NaOH and 60% ethanol achieved relatively high desorption efficiency, the adsorption capacity declined after three consecutive cycles, necessitating the search for more effective regeneration strategies. Further studies should evaluate the long-term stability and practical applicability of MSB-Fe in continuous, pilot-scale, real wastewater systems.

256. 题目: Effects of Biochar on Freezing Temperature and Unfrozen Water Content in Pb‐Contaminated Seasonally Frozen Soils: Implications for Mitigating Land Degradation
文章编号: N26082409
期刊: Land Degradation & Development
作者: Shanbo Han, Yaling Chou, Wei Cao, Fupeng Yang, Yu Wang, Xunkun Guo
更新时间: 2026-08-24
摘要: Freeze–thaw processes are important drivers of land degradation in cold regions, and soil freezing temperature and unfrozen water content are key parameters for characterizing soil hydrothermal conditions and water phase transitions during freezing. However, in the context of heavy metal pollution, there remains a lack of systematic understanding regarding biochar's (BC) regulatory role in the freezing behavior of seasonally frozen soil and the dynamic changes in unfrozen water content. Based on freezing and freeze–thaw experiments, this study investigated the effects of biochar on soil freezing temperature and unfrozen water content under various conditions, with the results subjected to statistical analysis. The findings showed that dry density and Pb content exert bidirectional regulatory effects on the freezing temperature and unfrozen water content of biochar‐amended soils. Under low initial water conditions, the biochar addition ratio is the primary factor affecting soil unfrozen water content. Specifically, 1% and 3% biochar additions significantly increase soil unfrozen water content; however, as biochar content increases further, its enhancing effect gradually diminishes. Under high initial water content, soil unfrozen water content is jointly regulated by biochar content, initial water content, and lead content. Correlation analysis indicated that lead content and initial water content exhibited significant positive correlations with unfrozen water content, while biochar content showed a weak negative correlation. ANOVA further revealed a significant interaction between biochar content and initial water content, indicating a synergistic regulatory effect, whereas the interaction between biochar and lead content was not significant. These findings reveal the influence patterns of biochar under multifactor coupling on the freezing processes of seasonally frozen soil and changes in moisture status. The results provide a theoretical basis for biochar‐assisted remediation of Pb‐contaminated soils and the mitigation of land degradation in seasonally frozen regions.

257. 题目: Divergent responses of soil organic carbon fractions, aggregation and microbial communities to straw incorporation strategies along temporal and soil depth gradients in Mollisols
文章编号: N26082408
期刊: Biology and Fertility of Soils
作者: Mengmeng Qu, Bowen Zhang, Xinyi Huang, Huancheng Pang, Han Zhang, Song Guan, Sen Dou
更新时间: 2026-08-24
摘要: While straw incorporation is widely implemented, it remains unclear how diverse straw incorporation practices shape microbial communities and their associations with soil organic carbon (SOC) fractions and soil aggregation, especially regarding maize straw morphology, straw–soil mixing uniformity, and straw incorporation depth. We conducted a one-year Mollisol field experiment comprising no-straw control (CK), shallow straw mixing into topsoil (SI), deep straw mixing into the 0–40 cm soil layer (DI), deep straw burial in the 30–40 cm subsoil (DB), and shallow mixing of pelletized straw into topsoil (PI). Relative to CK, PI and DB significantly increased SOC across the 0–40 cm profile by 10.4% and 9.36%, respectively. PI boosted topsoil mineral-associated organic carbon (MAOC) by 14.0%, and DB increased subsoil MAOC by 10.8%. However, all straw treatments markedly increased particulate organic carbon (POC) throughout 0–40 cm profile by 40.4%–70.5%, with maximum increments in PI and DB. Subsoil macroaggregate formation and aggregate-associated carbon exhibited stronger responses to straw incorporation than those in topsoil. Microbial taxa displayed distinct shifts between topsoil and subsoil, as well as across different stages of straw incorporation. This study revealed that the enhancements in POC, MAOC, aggregate-associated carbon, and soil structural stability synergistically promoted SOC accumulation following straw incorporation. Particularly, the bacterial communities showed significant associations with small-sized microaggregate- and silt/clay-associated carbon, whereas the fungal communities were positively correlated with SOC accumulation. Our findings confirm that PI and DB strategies possess remarkable potential for boosting SOC across 0–40 cm soil layer, supporting their extensive application in sustainable agricultural management.

258. 题目: Reactive oxygen species in earthworm casts: a hidden driver of CO2 emissions and Fe‑associated organic carbon formation
文章编号: N26082407
期刊: Biology and Fertility of Soils
作者: Zheng Ni, Bin Jia, Tianshu Liu, Yuntao Yuan, Yanpei Li, Hanzhong Jia
更新时间: 2026-08-24
摘要: Fresh earthworm casts are commonly known as hotspots of CO2 emissions, a phenomenon that has long been ascribed to enhanced microbial activity. However, the contribution of reactive oxygen species (ROS)-mediated abiotic oxidation to soil organic carbon (SOC) cycling in casts remains poorly understood. Here, we investigated ROS generation and its role in short-term SOC turnover in freshly deposited earthworm casts using electron paramagnetic resonance spectroscopy, molecular probe assays, and ROS scavenger experiments. Fresh casts showed pronounced production of O2•−, H2O2, and •OH after 24 h, approximately 1.27–1.46, 2.57–3.00, and 4.30–4.49 times higher than those in non-cast and bulk soils, respectively. ROS generation was primarily driven by abiotic reactions involving surface-adsorbed and structural Fe(II), whereas the microorganisms acted mainly as indirect regulators by promoting Fe(III) reduction and Fe(II) accumulation during gut passage. Scavenger experiments showed that ROS-mediated processes accounted for approximately 17.9% of total CO2 emissions from casts, indicating an abiotic oxidative contribution to short-term SOC mineralisation. Among the ROS species, •OH likely acted as the most reactive oxidant, whereas O2•− and H2O2 mainly functioned as upstream intermediates supporting •OH formation. In addition to promoting CO2 release, Fe-bound OC was increased by 10.9%, which was attributed to the synergistic effects of Fe transformation and ROS. These findings identify fresh earthworm casts as previously underrecognized hotspots of ROS production and reveal a coupled biotic–abiotic mechanism through which Fe(II) oxidation links •OH-driven short-term carbon loss with the retention of organic carbon by newly formed reactive Fe(III) phases.

259. 题目: Distribution of soil organic carbon in root zones at different distances from the maize basal stem axis and its response to organic materials
文章编号: N26082406
期刊: Journal of Soils and Sediments
作者: Kaixuan Wang, Sen Dou, Baozhao Feng, Boyan Zhang, Yuhan Xia, Dilimulati Yalihong, Yue Gu, Jingmin Yang
更新时间: 2026-08-24
摘要: Aims Aiming at the ambiguous boundary and high distinction difficulty between rhizosphere and non-rhizosphere soil (e.g., the complicated shaking-off method fails to achieve accurate delineation). Methods This study proposed a root zone soil classification method based on distances from the maize basal stem axis (MBSA): root-adjacent soil (R0, 0-5 mm), near-root soil (R5, 5-50 mm), secondary near-root soil (R50, 50-150 mm), and distant root soil (R150, 150-325 mm), to explore the spatial distribution characteristics of soil organic carbon (SOC) in the 0-20 cm root zone. It clarifies the horizontal distribution characteristics of root density traits (root length density, average root diameter per unit soil volume, root surface area density, and root volume density) and SOC at different distances, and investigates the correlation between root density traits and SOC with and without organic matter application. Results The results indicate that the values of all maize root density traits gradually decrease with increasing horizontal distance from the maize basal stem axis. The distribution trend of SOC was similar to that of root systems, with a key distinction: compared to the R0 zone, all treatments exhibited a significant “carbon (C) trough” in the R5 zone, with the reduction ranging from 2.1% to 10.0%. Root density traits showed a significant correlation with SOC before organic matter application, but this correlation weakened after fertilization. Conclusion This indicates that SOC sequestration in the root zone shifted from a “root-dominated” single-regulation model to an indirect model involving multiple interactions. This study provides new insights into the functional differentiation of root systems and the mechanisms underlying soil C sequestration in root zones, offering guidance for precision field management.

260. 题目: Distinct physical stabilization of organic carbon as it is protected in the silt plus clay fraction of a shallow loamy sand soil in a woody-encroached savanna grassland
文章编号: N26082405
期刊: Plant and Soil
作者: Ntombizodwa Khumalo, Vusi Mbanjwa, Lerato Sekhohola-Dlamini, Masibonge Gxasheka, Phesheya Dlamini
更新时间: 2026-08-24
摘要: Aims Although there is increasing evidence that the storage of soil organic carbon (SOC) is affected by woody plant encroachment in savannas, the underlying physical stabilization mechanisms controlling SOC partitioning among aggregate fractions remain poorly resolved, particularly in sandy soils. We assessed changes in SOC concentration and SOC stocks (SOCs), soil water‑stable aggregates, and physical protection mechanisms within aggregate size fractions of a woody-encroached savanna grassland in South Africa. Methods We sampled the topsoil layer of open grassland and woody-encroached grassland loamy sand soil. The collected bulk soil samples were separated into four aggregate size fractions: large macroaggregates (LM), small macroaggregates (SM), microaggregates (M) and silt plus clay (SICL) by wet sieving. Afterwards, bulk soil and separated aggregate fractions were analysed for SOC. Results On average, SOC was 45% higher in the woody-encroached grassland compared to open grassland. Correspondingly, SOCs in the woody-encroached grassland were 29% higher relative to open grassland. A larger proportion of the aggregates were dominated by SM and M, with a greater proportion of the SOC stabilized within the SICL of the woody-encroached grassland soil. Conclusions These findings indicate distinct mechanisms of SOC stability, storage and protection in woody-encroached grasslands linked to enhanced retention within the SICL fraction, facilitated by greater surface area and more exchange sites for SOC adsorption. The entrapment of SOC within the SICL fraction is desirable because it is highly stable, has a longer turnover time and contributes to long-term storage of SOCs in savanna grassland soils.