Geoderma最新文献

{"title":"Sources and fate of CO2 along the soil–aquifer–stream–atmosphere continuum (the Orgeval headwater catchment, France)","authors":"Josette Garnier ,&nbsp;Sophie Guillon ,&nbsp;Hocine Hénine ,&nbsp;Gilles Billen ,&nbsp;Nicolas Escoffier ,&nbsp;Benjamin Mercier ,&nbsp;Anun Martinez ,&nbsp;Jean-Marie Mouchel","doi":"10.1016/j.geoderma.2025.117297","DOIUrl":"10.1016/j.geoderma.2025.117297","url":null,"abstract":"<div><div>Few studies have examined CO₂ sources and pathways along the soil–aquifer–stream–atmosphere continuum. We measured the water concentration of dissolved CO₂, HCO₃^–, and dissolved organic carbon (DOC), together with ancillary variables (pH, total alkalinity [TA], and major ions [Ca²⁺, Mg²⁺, SO₄^2-, NO₃^–]), in piezometer transects and adjacent streams at a monthly interval over a 5-year period (2019–2023). Such a continuum was studied within a small catchment underlain by carbonate geology and subject to intensive agriculture.</div><div>On the basis of the values of Ca²⁺, Mg²⁺, SO₄^2-, and alkalinity in the upslope and downslope piezometers, we assumed that the more mineralized downslope water would characterize the slow groundwater flow component of the stream, while the less mineralized upslope water would reflect a fast sub-surface flow (surface runoff + agricultural drainage flow). These water flows components were calculated using the HYPE calibrated hydrological model.</div><div>Accounting for weathering reactions and using a mass balance of dissolved C fluxes, we found that the total alkalinity flux (as HCO₃^–) reaching the river (amounting to 29 Mmol yr⁻¹, i.e., 79 kgC ha⁻¹ yr⁻¹) derived for about one third from soil CO₂ respiration, one third from carbonate dissolution induced by the reaction with CO₂, and one third from carbonate dissolution induced by the acidity generated by nitrification of reduced N fertilizers.</div><div>The groundwater CO₂ fluxes to the stream (13 Mmol y^-1, i.e., 36 kgC ha⁻¹ yr⁻¹) were 2<!--> <!-->orders of magnitude lower than the total direct soil CO₂ flux emitted to the atmosphere. Most (at least 95 %).of the groundwater CO₂ fluxes was degassed once reaching the stream.</div><div>Dissolved organic carbon flux to the stream represented only ∼ 2 % of the total dissolved carbon flux to the stream; the input of dissolved CO₂ in rainfall to the soil–aquifer system amounted to less than 1 % of this total dissolved carbon flux to the stream.</div><div>The carbonate weathering induced by soil respired CO₂ amounted to ∼ 26<!--> <!-->kgC ha⁻¹ yr⁻¹ in the Avenelles sub-catchment, representing ∼ 0.5 ‰ yr⁻¹ of the total soil organic carbon stock. The alkalinity flux generated by this process might hence act as significant soil transient CO₂ sink, depending on the prevalence of downstream processes affecting the stream carbonate buffering and speciation.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"458 ","pages":"Article 117297"},"PeriodicalIF":5.6,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143868957","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Soil fauna promote litter mixture effects on nitrogen release but not carbon or phosphorus during decomposition in a subtropical forest","authors":"Pengpeng Dou ,&nbsp;Dunmei Lin","doi":"10.1016/j.geoderma.2025.117312","DOIUrl":"10.1016/j.geoderma.2025.117312","url":null,"abstract":"<div><div>Understanding how litter diversity drives decomposition is critical for linking plant diversity to ecosystem functioning. We conducted a 460-day field decomposition experiment using litter mixtures (1–4 species) placed in both fauna-accessible and excluded litterbags in a subtropical forest. Both additive partitioning and trait-based approaches were used to investigate the effects of litter mixing on mass loss and the release of carbon (C), nitrogen (N), and phosphorus (P). Overall, the litter mixtures exhibited limited non-additive effects on litter mass loss and C release, with significant negative selection effects that offsetting the weak complementarity effects. In contrast, N release showed strong positive net diversity effects in fauna-accessible mixtures, driven by significant complementarity and selection effects. Soil fauna amplified the diversity effect on N release but had no effect on P, which displaying primarily additive dynamics. Functional identity (community-weighted mean of leaf toughness and thickness) predominantly predicted litter mass loss and C release, while functional diversity (Rao’s quadratic entropy of litter N concentration) and identity jointly governed litter N release in the presence of fauna. Our findings demonstrate decoupled mechanisms for C and nutrient cycling, where physical traits constrain mass loss and C release while synergistic litter diversity-soil fauna interactions enhance N mineralization, highlighting context-dependent diversity effects and underscoring the importance of integrating multi-element perspectives and faunal interactions to predict biodiversity-ecosystem functioning relationships in detrital systems.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"457 ","pages":"Article 117312"},"PeriodicalIF":5.6,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143867915","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Divergent mechanisms driving microbial necromass in topsoil and subsoil along an altitudinal gradient on the Loess Plateau","authors":"Yuqian Li ,&nbsp;Xuyang Wang ,&nbsp;Xiaoming Mou ,&nbsp;Bin Jia ,&nbsp;Jie Lian ,&nbsp;Yayi Niu ,&nbsp;Xiangwen Gong ,&nbsp;Yuqiang Li","doi":"10.1016/j.geoderma.2025.117311","DOIUrl":"10.1016/j.geoderma.2025.117311","url":null,"abstract":"<div><div>Microbial necromass are one of the main sources of soil organic carbon (SOC) in terrestrial ecosystems. However, the characteristics of soil amino sugar accumulation and their contribution to the SOC pools across different altitudinal gradients and the influencing factors need to be further investigated. In this study, alpine grassland (AG), subalpine scrub (SS), alpine scrub (AS), and alpine meadow (AM) were selected along the altitudinal gradient in the Mt. Maxian. Soil amino sugars are used as biological markers for microbial necromass. Soil physical and chemical properties, microbial biomass, amino sugar content, and their contribution to SOC, and the driving factors of these changes were analyzed at the 0–20 cm and 20–40 cm soil layers. The results showed that: SOC, total nitrogen (TN) and total phosphorus (TP) contents significantly increased along the altitude but decreased with soil depth. Soil microbial necromass increased linearly with altitude and the microbial necromass content was higher in the topsoil than in the subsoil. Total microbial necromass of surface and subsoil contributed 40.21 % and 39.96 % of SOC, respectively, and the contribution of fungal necromass (37.45 % and 37.14 %) was significantly higher than that of bacterial necromass (2.76 % and 2.82 %). Soil microbial biomass and soil ecological stoichiometry directly affected the accumulation of soil microbial necromass, and had different effects on fungal and bacterial necromass. Microbial biomass and soil ecological stoichiometric ratio dominated the C accumulation process of bacterial and fungal residues in topsoil. In subsoil, however, soil ecological stoichiometric ratio and climate are important factors influencing C accumulation of bacterial and fungal residues. The findings of this study have important implications for predicting soil C cycling under global climate change.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"457 ","pages":"Article 117311"},"PeriodicalIF":5.6,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143867914","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nitrogen fertilization-induced acidity and suitability of δ13C to study the dynamics of soil inorganic carbon in agroecosystems","authors":"Mostafa Abdollahpour ,&nbsp;Dennis Hollemann ,&nbsp;Leopold Sauheitl,&nbsp;Georg Guggenberger,&nbsp;Kazem Zamanian","doi":"10.1016/j.geoderma.2025.117309","DOIUrl":"10.1016/j.geoderma.2025.117309","url":null,"abstract":"<div><div>Neutralization of soil inorganic carbon (SIC), i.e., dissolution of carbonate minerals caused by N fertilization-induced acidity, is an ongoing reaction in agroecosystems that leads to significant contribution of SIC to soil CO₂ emission. Analyzing δ¹³C natural abundance of the emitted CO₂ is commonly used to quantify the contribution of SIC in total CO₂ emission. However, carbonates recrystallization in isotopic equilibrium with soil respiration can lead to miscalculation, where despite detecting δ¹³C signal from carbonates in the emitted CO₂, the SIC stock may not necessarily change. We tested the effects of ammonium sulfate, urea, chicken manure, liquid pig manure and no fertilization (i.e. control) on soil carbonates neutralization and the contribution of SIC in total CO₂ emission over a 21 day incubation experiment. The alkali trap method was used to measure the total CO₂ emission and the isotopic composition of carbon (C) in the emitted CO₂ from the soil. Liquid pig manure followed by ammonium sulfate apparently led to the highest cumulative SIC-originated CO₂ emissions, while chicken manure and urea showed equally the smallest amount. Nitrate can support the estimation of SIC-originated CO₂ emission when nitrification is the only source of soil acidification. Dissolved Ca²⁺ concentration was a more robust proxy than <span><math><mrow><msubsup><mrow><mi>N</mi><mi>O</mi></mrow><mrow><mn>3</mn></mrow><mo>-</mo></msubsup></mrow></math></span> for quantification of SIC-originated CO₂ emission in our batch experiment, however, more evidences have to be collected before using Ca²⁺ as a proxy in open soil systems. Verification of the δ¹³C values by dissolved Ca²⁺ showed that the contribution of SIC to the total CO₂ emission is overestimated after organic N fertilization, whereas an underestimation in the contribution of SIC to the soil CO₂ emission was observed after inorganic N fertilization. In summary, the δ¹³C analysis could yield inaccurate results regarding the effects of N fertilization on the contribution of SIC in soil CO₂ emission which should be considered in the future studies. From an environmental point of view, it can be concluded that when the amounts of N, especially in ammonium form e.g. amino groups are relatively high in organic fertilizers as it was the case in liquid pig manure compared to inorganic fertilizers, organic and inorganic N fertilizers lead to comparable amounts of SIC loss. This should be considered in applying organic fertilizers as a sustainable strategy to slow down the rate of soil acidification.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"457 ","pages":"Article 117309"},"PeriodicalIF":5.6,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143855180","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reactive oxygen species generation in earthworm burrows and their impact in drilosphere organic carbon mineralization","authors":"Zheng Ni,&nbsp;Bin Jia,&nbsp;Yanpei Li,&nbsp;Junaid Latif,&nbsp;Yuntao Yuan,&nbsp;Fuhao Liu,&nbsp;Kai Li,&nbsp;Wenjun Jiang,&nbsp;Hanzhong Jia","doi":"10.1016/j.geoderma.2025.117301","DOIUrl":"10.1016/j.geoderma.2025.117301","url":null,"abstract":"<div><div>The drilosphere is a hotspot of carbon cycling in terrestrial ecosystems, yet the soil organic carbon (SOC) mineralization within this zone associated with reactive oxygen species (ROS) remains underexplored. Herein, we investigated the spatiotemporal variations of ROS in the drilosphere and evaluated their contributions to SOC mineralization. Fluorescence imaging revealed concentrated ROS hotspots within approximately 2.8 mm of soil surrounding earthworm (<em>Metaphire guillelmi</em>) burrows. Spatially, hydroxyl radicals (^•OH) and hydrogen peroxide (H₂O₂) contents in drilosphere soils were 2218.65 nmol kg⁻¹ and 309.03 μmol kg⁻¹, respectively, significantly higher than those in the background soil (883.92 nmol kg⁻¹ and 138.09 μmol kg⁻¹, <em>p</em> &lt; 0.01). Temporally, ^•OH and H₂O₂ contents increased in drilosphere during the first 14 days of incubation, but declined following the removal of earthworms. In contrast, ROS levels in background soils remained stable throughout the incubation period. Correlation analysis revealed that earthworm activity significantly influenced ROS dynamics by altering microbial diversity, soil pH, dissolved organic carbon, and the Fe(II)/Fe(III) cycle (r = 0.60–0.90, <em>p</em> &lt; 0.05). Among the ROS, ^•OH was an important contributor to SOC mineralization. Inhibiting ^•OH production decreased CO₂ emissions by 34.9 % and laccase activity by 21.6 %. The addition of exogenous ^•OH increased SOC mineralization rate from 25.76 to 50.36 μg C g⁻¹ soil d^-1 and laccase activity from 2.46 to 9.50 U g⁻¹, indicating that ^•OH stimulates CO₂ emissions by increasing enzyme activity. This study identifies earthworm burrows as hotspots for ROS production and provides detailed insights into their ecological role in SOC cycling.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"457 ","pages":"Article 117301"},"PeriodicalIF":5.6,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143855115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhancing proximal and remote sensing of soil organic carbon: A local modelling approach guided by spectral and spatial similarities","authors":"Qi Sun,&nbsp;Pu Shi","doi":"10.1016/j.geoderma.2025.117298","DOIUrl":"10.1016/j.geoderma.2025.117298","url":null,"abstract":"<div><div>Optical proximal and remote sensing of soils capture essential spectral features needed to develop spectra-based prediction models for soil organic carbon (SOC), which determines a variety of biogeochemical processes on Earth. At large scale, increasing soil heterogeneity complicates the response relationship between soil spectra and SOC, making global models ineffective for local SOC predictions. Here, we propose a local learning approach that searches spectrally and spatially similar samples for site-specific SOC predictive modelling. The approach was developed using three large-scale spectral datasets (n = 911), including soil RGB images acquired by a smartphone, laboratory visible and near-infrared spectra using diffuse reflectance spectroscopy (DRS), and remotely sensed bare soil spectra (RSBS) from Sentinel-2 imagery, and further validated against three independent datasets of the same types (n = 72) at catchment scale. Different spectral similarity metrics, and weighted combinations of spectral and geographical similarity matrices were tested to optimize the selection of local training samples. As a result, the optimal modelling strategy, with partial least squares regression (PLSR) as the local fitting algorithm, consistently produced superior performances (R²: 0.66 to 0.82) than the conventional global modelling approach (R²: 0.59 to 0.77) for all three data types. Increasing the weight assigned to geographical similarity during local learning enabled the selection of compositionally similar samples, which improved SOC prediction accuracy by 10.87 %, 2.50 %, and 7.21 % for RGB, DRS, and RSBS datasets compared to models relying on spectral similarity alone. Independent validation shows that the performance of global PLSR models deteriorated from regional to catchment scale, while the proposed local modelling approach could maintain the prediction accuracy for all three data types (R²: 0.64–0.80), proving its cross-scale transferability. These findings highlight the potential of integrating spectral and spatial information to optimize the local learning procedure for accurate SOC quantification and mapping, especially when dealing with complex datasets covering large spatial scales.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"457 ","pages":"Article 117298"},"PeriodicalIF":5.6,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143858942","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tide-driven biogeochemical gradient shapes the vertical profile of dark carbon fixation in intertidal wetlands","authors":"Bin Wang ,&nbsp;Yanling Zheng ,&nbsp;Bolin Liu ,&nbsp;Xinyu Wang ,&nbsp;Lin Qi ,&nbsp;Sai Yang ,&nbsp;Jie Zhou ,&nbsp;Zhirui An ,&nbsp;Jiawei Zhang ,&nbsp;Min Liu ,&nbsp;Lijun Hou","doi":"10.1016/j.geoderma.2025.117295","DOIUrl":"10.1016/j.geoderma.2025.117295","url":null,"abstract":"<div><div>Dark carbon fixation (DCF) is recognized as a vital carbon sink process in the biogeochemical cycle of coastal wetlands. Tidal hydrodynamic dynamics in intertidal wetlands significantly affect the physicochemical conditions, yet their impacts on DCF activities and the associated chemoautotrophs remain unclear. Here, we investigated the vertical distribution patterns of DCF rates and the dynamics of chemoautotrophs in intertidal sediments using ¹⁴C isotope tracing and metagenomic techniques. Results showed that DCF rates peaked in the subsurface layer (10–35 cm depth, 110.13 ± 28.71 mmol C m⁻³·d⁻¹), but were relatively lower in the surface layer (0–10 cm, 20.19 ± 5.93 mmol C m⁻³·d⁻¹) and the deep layer (80–100 cm, 13.79 ± 1.28 mmol C m⁻³·d⁻¹). Higher DCF activities in the subsurface layer might be attributed to more sufficient reducing substrates such as sulfide and ferrous iron (Fe²⁺), as well as the redox gradient shaped by tidal fluctuations. Metagenomic analysis highlighted that the Wood-Ljungdahl (WL) cycle was the predominant carbon fixation pathway for chemoautotrophs in intertidal sediments. The estimated DCF flux measured in the present study (50.96 mmol C m⁻² d⁻¹) was significantly higher than previous reported rates obtained exclusively from the surface sediments. In conclusion, this study enhances our understanding of the complex DCF process and provides scientific support for a more accurate evaluation of the carbon sink potential in intertidal wetlands.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"457 ","pages":"Article 117295"},"PeriodicalIF":5.6,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143855116","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"TTOP model simulation of long-term (1981–2100) permafrost dynamics of the Tibetan Plateau","authors":"Yufeng Zhao ,&nbsp;Yingying Yao ,&nbsp;Huijun Jin ,&nbsp;Xin Li ,&nbsp;Bin Cao ,&nbsp;Youhua Ran ,&nbsp;Xingxing Kuang ,&nbsp;Chunmiao Zheng","doi":"10.1016/j.geoderma.2025.117287","DOIUrl":"10.1016/j.geoderma.2025.117287","url":null,"abstract":"<div><div>The Tibetan Plateau (TP) covers the largest regions under low- and mid-latitude permafrost. The evolution of permafrost has significantly affected the hydrology, biogeochemistry, and infrastructure of Asia. However, model reconstructions of long-term permafrost evolution with high accuracy and reliability are insufficient. Here, spatial changes in mean annual ground temperature at the depth where the annual amplitude is zero (MAGT) on the TP since 1981 were modeled and validated based on temperature records from 155 boreholes, and future changes were predicted under scenarios from the Climate Model Intercomparison Project 6 (CMIP6). The results indicated that the MAGT on the TP was approximately 1.5 °C (2010 – 2018), and the corresponding permafrost extent on the TP is estimated to be approximately 1.03 × 10⁶ km², which is projected to decrease to 0.77 × 10⁶, 0.50 × 10⁶, 0.30 × 10⁶, and 0.17 × 10⁶ km² under the scenarios of shared socioeconomic pathway (SSP)126, SSP245, SSP370, and SSP585, respectively, by 2100. As predicted in the SSP585 scenario, permafrost is predicted to largely disappear from many basins of major Asian rivers, such as the Yarlung Zangpo-Brahmaputra, Nu-Salween, and Lancang-Mekong Rivers, between 2041 and 2060, followed by the Yellow and Yangtze Rivers between 2061 and 2080. Moreover, the original stable permafrost in the West Kunlun Mountains will change to transitional and unstable conditions. Our study offers comprehensive datasets of year-to-year ground temperatures and permafrost extent maps for the TP, which can serve as a fundamental resource for further investigations on the hydrogeology, engineering geology, ecology, and geochemistry of the TP.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"457 ","pages":"Article 117287"},"PeriodicalIF":5.6,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143855181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The molecular composition of soil organic matter is regulated by bacterial community under biochar application","authors":"Zongkun Yang ,&nbsp;Wenbo Liu ,&nbsp;Xiaoge Fan ,&nbsp;Han Gao ,&nbsp;Xiangrui Xu ,&nbsp;Cheng Liu ,&nbsp;Yanjun Chai ,&nbsp;Min Zhang ,&nbsp;Marios Drosos ,&nbsp;Shengdao Shan","doi":"10.1016/j.geoderma.2025.117308","DOIUrl":"10.1016/j.geoderma.2025.117308","url":null,"abstract":"<div><div>Soil organic matter (SOM) consists of diverse carbon compounds, which are influenced by microorganisms that affect its turnover and stability. However, changes in SOM molecular composition following biochar application and their interactions with the soil bacterial communities remain poorly understood. We aimed to evaluate SOM molecular composition, soil bacterial communities, and carbon cycle functional genes of bacteria in soils treated with biochar using pyrolysis–gas chromatography-mass spectrometry (py-GC/MS) and amplicon sequencing. The py-GC/MS results indicated that biochar increased the molecular diversity and significantly altered the molecular composition of SOM. In biochar-treated soils, the abundance of lignin-derived products increases, while lipids levels decrease. Biochar application shifted the soil bacterial life-history strategy towards copiotrophy, characterised by a higher copiotroph/oligotroph ratio and ribosomal RNA operon copy number. Procrustes analysis revealed that SOM molecular composition was strongly correlated with both the bacterial community and carbon cycle functional genes. Specifically, the SOM composition was closely associated with Gammaproteobacteria, Acidobacteria, and Chloroflexi. Additionally, SOM network analysis indicated that biochar enhanced SOM molecular complexity (i.e., node count, edge count, and average degree) primarily due to the accumulation of lignin-derived products. These findings highlight the potential of biochar to reshape the molecular composition of SOM via microbially mediated processes.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"457 ","pages":"Article 117308"},"PeriodicalIF":5.6,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143851879","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental and numerical investigations on spilled oil migration and contamination characteristics in freezing soils","authors":"Wansheng Pei ,&nbsp;Zeliang Ye ,&nbsp;Mingyi Zhang ,&nbsp;Jianguo Lu ,&nbsp;Jiazuo Zhou ,&nbsp;Weibo Liu","doi":"10.1016/j.geoderma.2025.117300","DOIUrl":"10.1016/j.geoderma.2025.117300","url":null,"abstract":"<div><div>Pipeline oil spills can lead to environmental pollution and alter the thermal state of soils in cold regions. This study investigatesd the characteristics of oil migration in freezing soils. A series of laboratory tests were conducted on soils with different temperature boundaries and initial water contents. Using porous media theory, a mathematical model was developed to describe the oil migration process, accounting for the ice-water phase change within soil pores and the influence of soil temperature. The model was validated by comparing simulation results with experimental data. The study revealed that, 1) the temperature of spilled oil significantly disrupts the soil’s thermal state, and the oil migration can be affected by several factors, e.g. the temperature gradient, gravity and concentration gradients within the soil. 2) soil temperature affects oil viscosity and the adsorption of soil particles, influencing the migration rate and diffusion range. The low permeability of frozen soil inhibits oil seepage. When the temperature boundary increases from −5 °C to −1 °C, the total oil infiltrating the soil increases by 142 %.3) Pore water content impedes oil migration due to the incompatibility between oil and water. A 32.5 % increase in spilled oil is observed when the initial water content reduces from 20% to 12%. This study provides a scientific basis for soil restoration following oil pipeline leak in cold regions.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"457 ","pages":"Article 117300"},"PeriodicalIF":5.6,"publicationDate":"2025-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143850492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}