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161. 题目: Thermochemical processing of sewage sludges: Comparative analysis of hydrochars and biochars for sustainable phosphorus recovery.
文章编号: N26071710
期刊: Science of the Total Environment
作者: Mozhdeh Alipoursarbani, Hossein Asadi, Christian Abendroth
更新时间: 2026-07-17
摘要: Securing sustainable phosphorus (P) resources from municipal sewage sludge is critical for circular nutrient management. This study investigates the effects of hydrothermal carbonization (HTC, 180 °C) and pyrolysis (450 °C and 600 °C) on two different sewage sludges: Stabilized Sewage Sludge (SSS) derived from an extended aeration activated sludge (EAAS) system, and Sludge Cake (SC) obtained from an anaerobic-anoxic-oxic (A/A/O) treatment process. Feedstock origin strongly governed phosphorus speciation, transformation pathways, and char properties during thermochemical processing. The two raw sludges were influenced by their original treatment, with SSS showing higher total phosphorus (TP = 39.04 mg g-1) but a lower Ca/P molar ratio (0.20) compared with SC (TP = 26.10 mg g-1, Ca/P = 0.50), indicating distinct P partitioning between mineral and organic fractions. Hydrochars (SH from SSS, CH from SC) showed moderate total P concentrations (TP) and retained some organic P (OP), whereas pyrolysis produced biochars with higher TP: 59.7 mg g-1 in SB600 (SSS) and 46.0 mg g-1 in CB600 (SC). OP decreased significantly from 6.38 mg g-1 (SSS) and 8.15 mg g-1 (SC) to below 2.5 mg g-1, while inorganic P (IP) became dominant. In SSS biochars, apatite phosphorus (AP) was the main fraction, while in SC biochars, non-apatite inorganic P (NAIP) remained significant. These contrasting behaviors are attributed to feedstock-dependent mineral compositions, where Fe- and Al-associated fractions in SSS promoted conversion of NAIP into AP, whereas the higher initial Ca content in SC favored NAIP retention. Solid-state 31P NMR confirmed that orthophosphate (Ortho-P) is the main P species, highlighting its bioavailability and thermal stability. Pyrolysis increased carbonization, decreased H/C and O/C ratios (down to 0.44 and 0.33 at 600 °C), and generated highly porous, thermally stable chars. Overall, these results demonstrate that both sludge type and thermochemical pathway critically influence char properties and phosphorus forms.

162. 题目: Influence of land use on soil properties and organic carbon pool distribution in deep soil layers of subtropical India.
文章编号: N26071709
期刊: Environmental Monitoring and Assessment
作者: Shrikant Badole, Ashim Datta, Krishna Chaitanya Anantha, Biswapati Mandal, P S Bodake
更新时间: 2026-07-17
摘要: Climate change poses serious concern for humanity. Globally, land-use change contributes nearly 20% of the total greenhouse gas (GHG) emissions. Understanding the vertical distribution of soil organic carbon (SOC) pools is crucial for evaluating regional and global C storage potential and for anticipating the impacts of climate change, yet studies on this aspect remain limited. In the present investigation, five land use types were selected - three agricultural systems with varied cropping intensities (CI), namely 300% CI (rice-potato-jute), 200% CI (rice-jute), and 100% CI (rice), fallow and forest land dominated by Shorea robusta, Dalbergia sissoo, and Bombax malabaricum. Soil profile samples were collected from 0-0.2, 0.2-0.4, 0.4-0.6, 0.6-0.8, 0.8-1.0, 1.0-1.5, and 1.5-2.0 m depth intervals. With increasing depth, soil pH and bulk density (BD) increased, whereas silt and clay content generally decreased in most land uses. The lowest pH (4.5) and BD (1.19 Mg m-3) were observed under forest land at 0-0.2 m depth, whereas the highest BD (1.61 Mg m-3) and pH (8.0) were obtained in 100% CI at 1.5-2.0 m, and fallow land at 0.8-1.0 m, respectively. Labile SOC fractions decreased with soil depth, whereas the proportion of recalcitrant carbon in the passive pool increased with depth. Overall, forest land stored highest SOC (126.3 Mg C ha-1) followed by fallow land (121.9 Mg C ha-1), while among the agricultural systems, the 300% CI exhibited the maximum SOC stock (89.1 Mg C ha-1) followed by 200% CI (86.1 Mg C ha-1) and 100% CI (56.4 Mg C ha-1) at the 2.0 m soil depth. These findings demonstrate that forest land maintained the highest SOC stocks while among the agricultural systems, diversified cropping systems with 300% CI exhibited greater potential for C sequestration and sustaining soil health in the terai region of subtropical India.

163. 题目: Biochar-earthworm-plant interactions regulate soil organic carbon stabilization and Cd immobilization in vegetable and corn cropping system.
文章编号: N26071708
期刊: Ecotoxicology and Environmental Safety
作者: Cevin Tibihenda, Yiqing Chen, Menghao Zhang, Hesen Zhong, Li Jia, Longhua Wu, Mikael Motelica-Heino, Ying Lu, Chi Zhang
更新时间: 2026-07-17
摘要: A dual strategy for carbon (C) sequestration and Cd remediation was developed by leveraging the synergistic effects of biochar and earthworms on soil organic C transformation and Cd bioavailability. However, the combined capacity of these amendments to simultaneously enhance soil organic C storage and reduce crop Cd uptake, particularly through the regulation of dynamic organic C pools, remains insufficiently understood. A field experiment was conducted to evaluate the individual and combined effects of biochar (600 g plot⁻¹) and earthworms (Amynthas aspergillum; 50 worms plot⁻¹) on soil organic C dynamics and Cd transfer in corn (Zea mays) and vegetables (Brassica campestris). To account for soil heterogeneity, samples were collected from non-planted, bulk, and rhizosphere soil zones. Microbial biomass was highest in corn fields treated with biochar alone, whereas earthworm activity significantly altered microbial community structure, particularly the Gram-positive-to-Gram-negative (G+/G-) and fungal-to-bacterial (F/B) ratios. Distinct soil organic C stabilization patterns were observed between crop systems: vegetable fields exhibited increased mineral-associated organic C (MAOC) and dissolved organic C (DOC), while corn fields promoted particulate organic C (POC) and higher POC/MAOC ratios. Redundancy analysis (RDA) revealed that POC was positively correlated with amorphous Fe and the activities of catalase, urease, and fluorescein diacetate (FDA) hydrolase, whereas MAOC was significantly associated with invertase activity and microbial community ratios (G+/G- and F/B). Partial least squares (PLS) analysis identified POC as the dominant organic C pool, primarily regulated by crop type and mediated by soil chemistry, microbial structure, and Fe oxide forms. Biochar application immobilized Cd by increasing POC content, the POC/MAOC ratio, exchangeable Ca, free Fe, and urease activity, while also promoting more stable Cd fractions, including oxidizable and residual forms. Consequently, biochar reduced Cd uptake by 8% in vegetables and 6% in corn. In contrast, earthworm activity enhanced MAOC, DOC, soil electrical conductivity (EC), and microbial community ratios (G+/G- and F/B), but also mobilized soil Cd, increasing total Cd accumulation by 15% in vegetables and 8% in corn under the combined treatment system. Random forest analysis identified crop biomass and the POC/MAOC ratio as the primary drivers of Cd uptake. Pearson correlation analysis further demonstrated that POC negatively correlated with Cd uptake, whereas MAOC positively influenced crop Cd accumulation. Overall, this study provides important insights into how the co-application of earthworms and biochar influences soil organic C storage and Cd dynamics in agricultural systems. While the combined strategy may improve soil C sequestration, caution is warranted because it may simultaneously compromise Cd stabilization, thereby increasing Cd bioavailability and accumulation in crops.

164. 题目: Chitosan-crosslinked microwave-engineered biochar alleviates lead stress in Brassica napus by improving soil functioning and plant performance in Pb-contaminated soil.
文章编号: N26071707
期刊: Journal of Environmental Management
作者: Fakhir Hannan, Yiwa Hu, Ahsan Ayyaz, Muhammad Iqbal, Muhammad Umair Yasin, Iram Batool, Juanjuan Li, Faisal Islam, Yasir Hamid, Muhammad Ahsan Farooq, Weijun Zhou
更新时间: 2026-07-17
摘要: Lead (Pb) contamination in agricultural soils reduces crop productivity and threatens food safety, highlighting the need for in situ amendments that lower Pb bioavailability while supporting soil functioning and plant performance. This study upgraded poultry manure-derived biochar through microwave activation and genipin-crosslinked chitosan modification (MPBCH), then evaluated its performance in a greenhouse pot experiment with Brassica napus grown in field-collected Pb-contaminated soil. Six treatments were compared: untreated Pb-stressed soil (CK), chitosan (CH), poultry manure biochar (PBC), microwave-prepared biochar (MPBC), chitosan-modified PBC (PBCH), and MPBCH. The MPBCH produced the strongest overall response, increasing soil pH from 5.84 to 6.95 and reducing DTPA-extractable Pb by 62.0%. Root and shoot Pb concentrations decreased by 52.1% and 57.9%, respectively, while immobilization-related indices consistently indicated lower Pb mobility and restricted soil-to-plant transfer. MPBCH also increased β-glucosidase, phosphomonoesterase, catalase, and urease activities by 43.74%, 40.22%, 60.24%, and 40.48%, respectively. Rhizosphere bacterial analysis showed the highest Shannon diversity (4.52) and Chao richness (1882.12) under MPBCH, with clear community separation in principal coordinates analysis, significant divergence by PERMANOVA (F = 3.73, R2 = 0.599, p = 0.0005), and enrichment of bacterial biomarkers. These belowground responses coincided with improved biomass, photosynthetic pigments, gas-exchange traits, nutrient status, antioxidant defense, and lower oxidative stress markers. Transcriptomic and qRT-PCR analyses supported reduced Pb-stress status under MPBCH, with shifts in carbon metabolism, glutathione metabolism, photosynthesis, and metal transport-related genes. Multivariate integration identified MPBCH as the strongest-performing treatment across the measured Pb immobilization, plant physiological, and soil biochemical responses.

165. 题目: Nitrogen Availability Modulates Root-Mediated Soil Organic Carbon Formation.
文章编号: N26071706
期刊: Environmental Science & Technology
作者: Xiaodong Wang, Lei Wang, Yarui Xin, Ying Zhang
更新时间: 2026-07-17
摘要: Living roots influence the formation of soil organic carbon (SOC) under straw incorporation, but the mechanisms underlying this process remain unclear. To elucidate these effects, we traced the fate of isotopically labeled maize straw into SOC via soil cores that were incubated in a soybean field. Our findings suggest that root ingrowth does not significantly affect the total SOC accumulation under straw incorporation but instead facilitates the allocation of SOC into stable SOC pools. However, the formation of stable SOC differs fundamentally between low-nitrogen (LN) and high-nitrogen (HN) soils. In LN soils, root ingrowth promotes the accumulation of stable SOC by promoting the transfer of straw-derived carbon into occluded particulate organic carbon (oPOC) and mineral-associated organic carbon (MAOC). In contrast, root ingrowth reduces the contribution of straw-derived C to stable SOC in HN soils, but this reduction may be offset by the incorporation of rhizodeposited C into oPOC and MAOC. Further research indicates that these different patterns are driven by a stoichiometric imbalance between the microbial demand for carbon and nitrogen and their resource availability. These findings provide mechanistic insights into how the presence of roots under straw incorporation influences SOC formation, deepening our understanding of root-mediated SOC sequestration.

166. 题目: From Naturally Occurring to Engineered Nano-Biochar: Properties, Feasibility, and Challenges for Sustainable Environmental Remediation.
文章编号: N26071705
期刊: Environmental Science & Technology
作者: Dongbo Wang, Junyi Lin, Juexuan Tang, Yukui Fu, Xuran Liu, Wei Wei, Bing-Jie Ni
更新时间: 2026-07-17
摘要: Nano-biochar, present both as naturally occurring pyrogenic carbon and as an engineered product of controlled pyrolysis, with particle sizes typically ranging from a few to several hundred nanometers, exhibits up to 97-fold greater specific surface area, 20-fold higher maximum adsorption capacity for methylene blue, and enriched oxygen-containing surface functional groups (e.g., ─OH, ─COOH, ─C═O) relative to bulk biochar, emerging as a promising nanomaterial for environmental remediation. Despite growing research interest, existing reviews have focused predominantly on its beneficial properties, leaving toxicity, recoverability, and scalability insufficiently addressed, which limits the translation of nanoscale properties into engineering practice. To bridge this gap, this review critically synthesizes current knowledge on nano-biochar from an engineering application perspective, covering its properties, remediation benefits, technical feasibility, and integration with advanced technologies including artificial intelligence, membrane reactors, advanced oxidation processes, and 3D printing. Application risks and safeguard strategies are critically assessed, alongside a conceptual sustainable paradigm to connect nanoscale material performance with real-world deployment. Future studies are suggested to prioritize reliable detection techniques, improved recovery or detoxification strategies, and low-input, high-efficiency technologies within a One Health framework to ensure safe deployment.

167. 题目: Investigation of Adsorption Mechanisms in Competitive and Non-Competitive Systems: Cadmium Immobilization in Contaminated Calcareous Soil Amended with Bone-Derived Biochar
文章编号: N26071704
期刊: Water, Air, & Soil Pollution
作者: Sobhan Mohamadi, Ghasem Rahimi, Abolfazl Khademi-Jolgeh Nezhad, M Mirari Antxustegi, María Gonzalez-Alriols
更新时间: 2026-07-17
摘要: Biochar (BC) has emerged as a promising soil amendment for reducing the bioavailability and toxicity of heavy metals such as cadmium (Cd) in contaminated soils. This study investigates the effectiveness of cow bone-derived biochar (CBBC), produced by pyrolysis at 550 °C, and ZnCl₂-activated biochar (A-CBBC) for Cd immobilisation in calcareous soils. Comprehensive characterisation of CBBC and raw bone powder (BP) was performed using elemental analysis, X-ray fluorescence (XRF), Brunauer–Emmett–Teller (BET) surface area analysis, scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) spectroscopy. Cadmium mobility was assessed through sequential fractionation and adsorption isotherm experiments under both competitive and non-competitive conditions. The results showed a reduction of approximately 10% in the exchangeable Cd fraction and the mobility factor (MF) in soils amended with 5–7% CBBC after six months of incubation. Adsorption isotherms indicated that soluble Cd concentrations were approximately twice as high under competitive conditions than under non-competitive conditions. Cadmium concentrations in untreated soils were 2.7-fold higher than those in soils amended with CBBC and BP. Relative to the control, CBBC and BP increased Cd adsorption by approximately 300 and 140 µmol kg⁻1, respectively. The observed reductions in Cd mobility are consistent with enhanced sorption associated with cation exchange and surface complexation, although these mechanisms are inferred from adsorption behaviour and fractionation data, not directly verified by spectroscopic analysis. Overall, the findings highlight the potential of CBBC and BP as effective amendments for reducing Cd mobility in calcareous soils and support their application as sustainable remediation strategies for heavy-metal-contaminated alkaline environments.

168. 题目: Microbial mechanisms of carbon turnover in humic acid-amended paddy soils
文章编号: N26071703
期刊: Journal of Soils and Sediments
作者: Shuwei Sun, Xiaoxue Zhang, Shuigang Wen, Senpei Lin, Minghao He, Lihua Zhou, Yong Yuan
更新时间: 2026-07-17
摘要: Purpose Humic acids (HAs) are widely recognized as soil amendments that improve soil quality, but their specific influence on carbon turnover dynamics in soils has yet to be fully elucidated. This study investigated how different types of HAs regulate the transformation pathways of soil organic carbon components and their underlying microbial control mechanisms. Materials and methods Neutral (Guangdong) and acidic (Jiangxi) paddy soils were spiked with three HAs—synthetic (straw-derived, SHA), peat-derived (PHA), and compost-derived (cattle manure, CHA)—at 5 g/kg. Under 30-day anaerobic incubation, CH4 and CO2 emissions, soil organic carbon (SOC), environmental parameters, and microbial communities were monitored. Results and discussion In neutral and acidic soils, SHA significantly increased CH4 production by 68.32-fold (from 0.13 to 8.8 µmol/g) and 23.3%, respectively. It also significantly elevated SOC by 21.82% and 20.39%. In contrast, PHA and CHA exerted lesser effects on carbon turnover. Microbial analysis revealed that SHA significantly altered microbial community structure and carbon metabolic functions, with promoted acetate-type and hydrogen-dependent methanogenesis. Moreover, SHA stimulated the DC/4-HB pathway but inhibited rTCA and WL pathways, whereas PHA and CHA exhibited opposite trends. Correlation indicated that structure-dependent effect of HAs on microbial carbon turnover. SHA, with its high aliphatic content, was the most effective driver of carbon transformation and methane emissions, surpassing the aromatic macromolecules PHA and CHA. Conclusion These findings indicate that HAs’ chemical complexity drives short-term microbial carbon turnover. However, given the substantial CH₄ emissions induced by SHA, long-term assessments are essential before recommending specific HA amendments for soil carbon sequestration.

169. 题目: Combined effect of biochar and seed priming on soil fertility and physio-biochemical traits of sweet corn (Zea mays L.) seedlings under drought stress
文章编号: N26071702
期刊: Plant and Soil
作者: Salih Demirkaya, Güney Akınoğlu, Elif Öztürk Ay, Nursaç Serda Kaya, Ömer Taş, Abdurrahman Ay, Gürkan Bilir, Deniz Ekinci, Coşkun Gülser
更新时间: 2026-07-17
摘要: Aims This study evaluates the combined effects of biochar and seed priming on soil properties and physio-biochemical responses of sweet corn seedlings under different drought conditions. Methods Three irrigation regimes were used to simulate drought stress: 100%, 75%, and 50% field capacity. Seeds were hydroprimed (HP) with distilled water, primed with 100 µM melatonin (MP), or control, and sown in pots with or without rice husk biochar (1%, w/w). Plant growth attributes and soil fertility were assessed. Results Drought stress significantly suppressed growth attributes. Compared with FC100, FC50 reduced fresh and dry biomass by 17.1% and 18.4%, respectively, while WUE decreased from 1.22 to 1.05 g mm⁻1. Among the priming treatments, HP produced the highest dry biomass (5.09 g pot⁻1), whereas MP resulted in the lowest (4.06 g pot⁻1). Biochar application consistently improved RWC and WUE, with the MP with biochar application achieving the highest WUE (1.18 g mm⁻1). Drought altered nutrient dynamics by increasing shoot Ca and Mg and root N and K, while reducing soil available P. Oxidative damage, indicated by elevated MDA, intensified under drought, accompanied by increased antioxidant enzyme activities. Biochar amendments significantly reduced MDA and moderated antioxidant responses. Soil organic carbon (0.69–0.88%) and exchangeable K remained higher in biochar-amended pots across all drought levels. Conclusions The combined application of rice husk biochar and seed priming effectively mitigated drought stress by improving soil properties, enhancing plant water relations, and moderating physiological and biochemical stress responses. This synergy supports healthier seedling development and improved drought resilience in sweet corn.

170. 题目: How C: N imbalance regulates biochar priming: response of main microbial groups in soils with contrasting fertility
文章编号: N26071701
期刊: Biology and Fertility of Soils
作者: Weiwei Lu, Yanan Wang, Huili Geng, Honghua Ruan
更新时间: 2026-07-17
摘要: Priming effect (PE) of exogenous organic matter on native soil organic carbon (SOC) is a key driver of soil carbon (C) dynamics. However, how biochar regulates PE and microbial mechanisms remains unclear, limiting accurate assessment of soil C sequestration. We conducted a 360-day incubation experiment with 13C labeling to investigate PE dynamics and underlying microbial mechanisms induced by two types of 500 °C biochar (rice straw (RB500) and poplar twig (PB500)) in two contrasting soils: high-fertility (SH) and low-fertility (DT). Six treatments were included: S-CK, S-RB500, S-PB500, D-CK, D-RB500 and D-PB500. Initial negative PE was observed in all biochar-amended soils. Positive PE occurred mainly at the mid-incubation (~ 60–120 d) in SH soil and at the late incubation (> 180 d) in DT soil. Furthermore, PB500 induced an earlier transition from negative to positive PE than RB500 in both soils. In SH soil, compared with the early and late incubation stages, S-PB500 exhibited the highest C: N imbalance (4.43) and specific activities of N-acetyl-β-D-glucosaminidase and leucine aminopeptidase (0.20 and 4.89 µmol g C− 1 h− 1, respectively) at the mid-incubation stage, and these patterns were more consistent with “microbial N mining” In contrast, both D-RB500 and D-PB500 in the DT soil showed the lowest C: N imbalance (0.24–0.45) and the highest microbial biomass C during the late incubation stage, matching the patterns of “microbial stoichiometric decomposition”. This study proposes potential mechanisms for biochar-induced positive PE in contrasting forest soils and offers new insights into biochar use and soil C sequestration.

171. 题目: Total copper explains variation in soil organic carbon accumulation but not in situ soil respiration: An ecosystem evaluation of a century-old wood impregnation site.
文章编号: N26071308
期刊: Environmental Toxicology and Chemistry
作者: Ingrid Rijk, Michaela Zeiner, Dan B Kleja, Linee Goswami, Alf Ekblad
更新时间: 2026-07-13
摘要: Soils have become prominent and long-term sinks for contaminants, which leads to concerns about disruption of microbially driven processes in the soil carbon (C) and nitrogen (N) cycles. This field study used a 100-year-old copper (Cu) gradient (50-2,300 mg kg-1 dry wt) in a previous wood impregnation site to evaluate impacts on soil physicochemical properties, microbial functionality, and vegetation aided by stable isotopic approaches. At 0-5 cm depth, Cu had no effect on microbial biomass and activity (in situ substrate-induced respiration; C4-SIR). At 5-10 cm depth, microbial biomass decreased and soil organic C (SOC) and N increased in areas of high Cu. Subtle changes in soil and leaf δ13C and δ15N marked the site, with 1‰ depletion of δ15N, and 0.5‰-2‰ increase of δ13C with higher Cu. To identify predictors of SOC variation and soil respiration, multivariate modeling with partial least squares regression (PLSR) was applied. The PLSR indicated that total Cu positively correlated with higher SOC content across all soil layers, explaining 32% variance at 0-5 cm depth, 67% at 5-10 cm, and 11% at 10-15 cm. At 0-5 cm depth, moss coverage, δ15N, fine root biomass, and in situ basal respiration and C4-SIR rates influenced the final PLSR model (64% variance explained). At 5-10 cm depth, δ13C was another strong predictor of SOC. The PLSR showed that Cu could not directly explain variation of soil respiration rates, whereas SOC stock, root biomass, microbial biomass N, and δ15N seemed more important predictors. The results indicate a current acclimated microbial community in upper soil, but prevailing impacts in lower layers. Soil Cu contamination has left an imprint in the area in the form of SOC accumulation and subtle stable isotopic gradients, which could serve as integrative markers of C and N cycling in disturbed ecosystems.

172. 题目: CO2-Assisted Pyrolysis of Mn-Loaded Biomass for Syngas Generation and Periodate-Activating Biochar Production.
文章编号: N26071307
期刊: Environmental Research
作者: Joohyung Lee, Youn-Jun Lee, Hocheol Song, Eilhann E Kwon
更新时间: 2026-07-13
摘要: Mn-biochar composite, which incorporates redox-active Mn sites into a carbon scaffold, is an active catalyst for periodate (PI) activation. Nevertheless, its scalable production remains challenging because conventional pyrolysis offers limited energy recovery. Here, Mn-impregnated switchgrass (SG) was pyrolyzed under CO2-assisted conditions to redirect biomass carbon conversion from condensable oxygenates to syngas. The temporal evolution of gaseous products indicated that Mn impregnation into SG promoted syngas generation during CO2-assisted pyrolysis. Correspondingly, analysis of biocrude composition indicated that Mn and CO2 facilitated the secondary conversion of condensable oxygenates. Mn-biochar composite produced under CO2-assisted pyrolysis (MnSGB (CO2)) displayed pronounced redox features, indicating the presence of active Mn species. MnSGB (CO2) showed lower charge-transfer resistance than Mn-free biochars. Consequently, MnSGB (CO2) exhibited superior catalytic performance for PI activation, achieving >99% bisphenol A removal. Mechanistic investigations also suggested that enhanced catalytic activity was driven by Mn-mediated interfacial electron transfer and the resulting 1O2 generation.

173. 题目: Soil quality degradation induces synergistic evolution of carbon components: Microbial extracellular polymeric substances - driven mechanism.
文章编号: N26071306
期刊: Journal of Environmental Management
作者: Renjie Hou, Sisi Liu, Anshuang Su, Miao Wang, Hai Wang, Sen Lin, Xin Zhao, Xu Leng, Jian Zhang, Lan Luo, Chunjiao Wang
更新时间: 2026-07-13
摘要: The complex climatic background of cold regions induces and aggravates soil erosion, which accelerates soil quality degradation and weakens the stability of farmland soil carbon pools. As a biological cementing agent sustaining soil aggregate structure, extracellular polymeric substances (EPS) serve as a core mediator regulating soil structural stability and carbon pool loss. However, the cascade response mechanism by which EPS drives the transformation of labile organic carbon under environmental stress remains unclear. To effectively reveal the regulatory rule of EPS on the evolution of soil carbon fractions, four typical farmland soils in cold regions (Chernozem, Albic soil, Meadow soil, Dark brown soil) were selected for simulated erosion experiments under rainfall, freeze-thaw and snowmelt conditions. This study systematically analyzed the coupling effects of erosion stress on soil aggregate structure, microbial community function and variations in labile organic carbon fractions, and identified the key driving factors responsible for soil carbon loss. The results indicated that EPS plays a core mediating role in the coupling process of soil structural stability and carbon cycling. Erosion disrupts soil aggregate structure and thereby increases soil porosity. Relative to the control, the porosity of dark brown soil rose by 14.56%, 15.75% and 15.91% under rainfall, freeze-thaw and snowmelt erosion, respectively. Meanwhile, soil erosion markedly reduced key EPS component contents. The degraded soil-water environment decreased microbial community diversity and suppressed the expression of EPS synthesis-related genes. Correspondingly, EPS-polysaccharide content declined by 42.63%, 23.67% and 41.71% under the three erosion treatments above. In addition, the impairment of EPS barrier function results in the reduction of labile organic carbon content in soil. The stability of the four soil types follows the order: Dark brown soil > Chernozem > Meadow soil > Albic soil. In conclusion, EPS is not only a cementing substance for maintaining soil structure, but also a biological barrier against carbon loss. This study is expected to provide a scientific basis for the remediation of degraded soil and the establishment of stable soil carbon pools.

174. 题目: Soil organic carbon assessment in perennial agriculture - a base study of Kernza in Alnarp, Sweden.
文章编号: N26071305
期刊: Environmental Monitoring and Assessment
作者: Jonas Ardö, Maja Holm, Karl Ljung
更新时间: 2026-07-13
摘要: Increased soil organic carbon (SOC) sequestration reduces atmospheric CO2 and builds soil health. A conversion from annual crops to perennial crops may decrease negative environmental impacts and promote desired ecosystem services. Soil carbon credit systems and environmental monitoring require reliable verification of SOC change. Here we report a baseline survey of SOC for an agricultural study site in southern Sweden comprised of a perennial grain (Kernza), and a traditional rotation of annual crops as reference. We performed a systematic baseline soil sampling and calculated the minimal detectable difference to determine sample requirements for significant verification of SOC sequestration over time. The potential benefits of stratified sampling, based on a satellite-based vegetation index, flow accumulation and soil type, were investigated. Results indicate that 48% of the SOC was located in the upper 30 cm and > 70% in the upper 60 cm. SOC below 1 m soil depth was low. The minimal detectable difference, based on 10 soil samples, was 3.4 mg C g soil-1, equivalent to 1530 g C m-2 in the upper 30 cm. Stratified sampling showed no difference among strata for vegetation index and flow accumulation. We conclude that the baseline survey of SOC will benefit forthcoming studies of carbon cycling within the study site. The pay back from applying stratified sampling seems low, as this is a rather homogenous study area. The minimal detectable difference approach requires an unreasonable number of soil samples to allow significant and valid verification of differences in SOC sequestration over time.

175. 题目: Paddy drainage channels regulate dissolved organic matter transport and transformation across contrasting agricultural landscapes.
文章编号: N26071304
期刊: Environmental Monitoring and Assessment
作者: Lei Ding, Liyin Qu, Ting Wang
更新时间: 2026-07-13
摘要: Agricultural carbon export is an important driver of aquatic carbon cycling. As the key linkage between croplands and river systems, the regulation of drainage channels on dissolved organic matter (DOM) turnover remains unclear. Here, we investigated water quality, dissolved organic carbon (DOC), bioavailable DOC (BDOC) and DOM optical properties in inlet and outlet waters of paddy drainage channels along an urban-mountain gradient in southeastern China, using UV-Vis and fluorescent spectroscopy coupled with PARAFAC. Urban paddy showed significantly higher DOC, BDOC and optical component values than mountain paddy due to stronger anthropogenic sewage inputs and nutrient stimulated algal production. In contrast, mountain paddy showed lower DOM abundance but a higher photochemically degraded humic-like component and aromaticity due to weaker tillage intensity and higher elevation. DOC decreased along 76% of the drainage channels, whereas DOM aromaticity increased due to the microbial degradation of bio-labile DOM, leading to increased export of recalcitrant DOM. However, a net increase in DOC was observed in the remaining drainage channels, suggesting that enhanced in-channel production under high nutrient loading exceeded the removal effect. Our findings provide new insight into the influence of tillage intensity and landscape change on agricultural carbon cycling and water management.

176. 题目: Human-associated modulation of urban DOM heterogeneity: transformation toward aquatic carbon sink-like and carbon source-like molecular pools.
文章编号: N26071303
期刊: Environmental Research
作者: Shuang Wu, Manjie Li, Xiaozhou Yang, Jing Sun, Ding He
更新时间: 2026-07-13
摘要: Dissolved organic matter (DOM) plays a vital role in the safety and stability of drinking water, yet the molecular characteristics of DOM across urban aquatic systems remain insufficiently elucidated. In this study, advanced spectroscopic techniques and Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS) were employed to characterize DOM in municipal tap water (TW) and corresponding source water (SW) from Shenzhen, China. Comparative analyses revealed significant reductions in humic-like fluorescence, molecular weight, aromaticity, unsaturation, and N/S-containing molecules from SW to TW, primarily attributable to water treatment and distribution processes. Notably, while DOM in SW samples exhibited high molecular similarity across regions, TW samples displayed marked regional heterogeneity within the city. Specifically, TW from the eastern region contained higher concentrations of aliphatic compounds, peptides, and P-containing molecules, while TW in the middle and western regions possessed a greater abundance of highly unsaturated compounds. These findings enabled the further identification of two distinct human-associated transformation pathways: the eastern region favored the formation of carbon source-like compounds (e.g., lipids and peptides), whereas the western and middle regions promoted the accumulation of carbon sink-like substances (e.g., highly unsaturated and carboxyl-rich alicyclic molecules). This divergence indicates region-specific carbon cycling dynamics within the urban water system, highlighting a potential trade-off between risks of secondary pollution and toxic compound enrichment. Molecular-level insights generated by this study are essential for understanding DOM fate and carbon cycling within urban water systems, ultimately informing strategies to ensure the reliable and safe provision of drinking water.

177. 题目: Impact of chlorine on nutrient and antibiotic adsorption from human urine by modified biochar.
文章编号: N26071302
期刊: Journal of Environmental Management
作者: Sayeda Ummeh Masrura, Erica Marti, La Zhuo, Zhe Yang, Eakalak Khan
更新时间: 2026-07-13
摘要: Human urine is a promising resource for nutrient recovery; however, chlorine from toilet cleaning agents may interfere with adsorption-based recovery processes. In this study, the impact of chlorine during the adsorption of nutrients (N and P) and antibiotics in source-separated urine by biochar was investigated. Sewage sludge biochar pyrolyzed at 550°C and 700°C (SS700) modified with dimethyl sulfoxide and citric acid combined with sucrose (CAS) were selected for adsorption based on preliminary experiments. Langmuir isotherm and pseudo-second-order kinetics models provide comparatively better empirical fits to the experimental data, suggesting that monolayer chemisorption is the dominant adsorption behavior. There was a significant difference between the adsorption capacities of ammonia-N and antibiotics with and without chlorine specifically for SS700 modified with CAS biochar, which adsorbed 714 μg/g and 170 μg/g of trimethoprim (320% increase), 2500 μg/g and 833 μg/g of ciprofloxacin (200% increase), 53.14 mg/g and 49.43 mg/g of ammonia-N (7% increase), with and without chlorine, respectively. The formation of surface oxides on biochar through chlorination and chloramination (from chlorine reacting with ammonia--N) potentially affected the adsorption process. Chlorine had minimal impact on phosphorus recovery due to surface blocking by chlorinated byproducts. This study reveals the influence of chlorine, on the adsorption capacities of biochar for nutrients and antibiotics, particularly altering the concentration of nutrients in urine solutions and thereby impacting the nutrient recovery process.

178. 题目: Saline Permafrost and Cryopegs as Potentially Important Sources of CO 2 —Assessing Organic Carbon Mineralization Potentials on the Alaskan Coastal Plain
文章编号: N26071301
期刊: Global Change Biology
作者: Fabian Seemann, Mackenzie R Baysinger, Susanne Liebner, Claire Treat, Michael Zech, Maren Jenrich, Guido Grosse, Benjamin M Jones, Jens Strauss
更新时间: 2026-07-13
摘要: Thermokarst lake and drained lake basin (DLB) dynamics are intensifying across the Alaskan Arctic Coastal Plain. Thawing, drainage, and erosion expose surface and deep sediments (> 1 m) to aerobic conditions, with saline deposits being particularly vulnerable due to freeze‐point depression. As organic carbon mineralization remains poorly constrained, we determined potentials with an aerobic one‐year long incubation at 10°C in permafrost upland, lake talik, lake cryopeg, and refrozen saline DLB sediments. We linked CO 2 production to biochemical, hydrochemical, and microbial factors, and assessed carbon alteration via repeated n ‐alkane analyses. After 382 days, average CO 2 production was 7.0 ± 0.4 mg C g −1 dry weight (DW), with DLB surface peat yielding the most (40.5 ± 2.7 mg C g −1 DW), and carbon‐poor cryopeg deposits (1.4 ± 0.1 mg C g −1 DW) and refrozen saline permafrost (1.5 ± 0.02 mg C g −1 DW) the least. Total organic carbon (TOC) was the main driver of CO 2 production, while age, nitrogen content, electrical conductivity, water content, pH, and microbial abundance also correlated significantly with CO 2 production. Normalizing production to TOC contents, saline permafrost and cryopeg sediments showed similar CO 2 production to active layers, stressing the importance of potentially carbon‐rich saline deposits. TOC normalization revealed that carbon characteristics (δ 13 C, alkane content, ACL) also significantly influenced CO 2 production. The n ‐alkane based quantification of carbon alterations during the incubation further contributes to the understanding of carbon cycling at the molecular level. n ‐Alkane contents increased on average by 153% and the carbon preference index (CPI) rose from 13.2 to 15.8, likely due to newly produced alkanes, preferential degradation, and desorption processes. This indicates strong responses of the carbon pool and raises questions about the reliability of the CPI as a degradation proxy. Altogether, our study highlights the overlooked role of salinity in CO 2 production from Arctic coastal plains which could substantially shift carbon balances.

179. 题目: Unravelling the importance of organic phosphorus forms in rice root iron plaque
文章编号: N26071203
期刊: Journal of Environmental Quality
作者: Sara Martinengo, Frank Linam, Matt Limmer, Maria Martin, Luisella Celi, Angelia L Seyfferth
更新时间: 2026-07-12
摘要: Rice ( Oryza sativa L.) plants accumulate phosphorus (P) on iron (Fe) plaque deposited on root surfaces. We aimed to investigate P speciation in rice root Fe plaque using x‐ray absorption near edge structure (XANES) spectroscopy coupled to conventional techniques. We examined Fe plaque samples from rice experiments in different soils. Samples deposited on filters yielded sufficiently thin, concentrated samples with high‐quality spectra despite low P concentrations. The low P concentrations in Fe plaque prevented us from using L‐edge P XANES for organic P differentiation, but allowed K‐edge P XANES. Fits of K‐edge P XANES data showed that organic P comprised from 40% to 70% of root plaque P, while inorganic P represented only a minor fraction. These findings demonstrate the importance of organic P in the rice rhizosphere and may lead to targeted P fertilization with minimal environmental impact.

180. 题目: Root Order Dependent Changes in Fine‐Root Substrate and Soil Environment Regulate Soil Organic Nitrogen Fractions Under Acid Rain and Nitrogen Deposition
文章编号: N26071202
期刊: Land Degradation & Development
作者: Xiongfei Zhang, Xingyu Zhang, Jinchi Zhang, Jialei Ren, Chong Li, Hui Nie, Jingyi Zeng, Xuanran Yu, Jie Lin, Tingyu Sun, Xin Liu
更新时间: 2026-07-12
摘要: Acid rain and nitrogen deposition are important environmental stressors affecting soil nitrogen cycling in subtropical forests, whereas fine‐root decomposition represents a major pathway for soil organic nitrogen (SON) input and transformation. However, how substrate changes in different root orders interact with soil environmental shifts to regulate SON fractions remains unclear. Here, we conducted three complementary decomposition experiments in a subtropical Chinese fir ( Cunninghamia lanceolata ) plantation to disentangle the effects of fine‐root substrate changes, soil environmental changes, and their combined in situ effects on SON fractions and depolymerase activities. The results showed that acid rain and nitrogen addition altered the initial chemical composition of fine roots before decomposition: total carbon in higher‐order roots decreased by 11.2%–14.4%, whereas lignin and cellulose contents increased mainly in lower‐order roots. Under a common soil environment, fine‐root substrate origin and root order jointly differentiated SON fractions and stimulated most depolymerase activities. Higher‐order roots tended to retain more acid‐hydrolyzable organic N under CK‐ and N‐derived substrates, whereas lower‐order roots showed stronger SON accumulation and enzyme responses under acid‐rain‐related substrates. By contrast, under a common fine‐root source, nitrogen addition promoted the accumulation of some acid‐hydrolyzable organic nitrogen fractions, while acid rain increased acid‐hydrolyzable amino acid nitrogen and modified enzyme responses. Under in situ conditions, fine‐root substrate changes and soil environmental shifts showed a synergistic effect, increasing some acid‐hydrolyzable organic nitrogen fractions by 16%–32% relative to the control. Model analyses further identified soil pH, total nitrogen, and protease activity as key predictors of SON transformation. These findings indicate that SON fraction changes under acid rain and nitrogen deposition are jointly regulated by fine‐root substrate quality and soil environmental conditions. Distinguishing the functional differentiation between lower‐order absorptive roots and higher‐order transport roots provides a more accurate understanding of root‐soil interactions and soil nitrogen cycling in Chinese fir plantations.