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61. 题目: Biochar Addition Changes the Aggregation of Clay Mineral and Natural Soil Nanoparticles via Different Mechanisms
文章编号: N25031804
期刊: European Journal of Soil Science
作者: Qi‐rui Li, Chen‐yang Xu, Zeng‐chao Geng, Fei‐nan Hu, Chun‐li Wang
更新时间: 2025-03-18
摘要: Wide application of biochar and subsequent release of biochar nanoparticles (NPs) significantly impact the stability of natural clay minerals and soil NPs, which are crucial for soil quality and play a vital role in determining the fate of nutrients and contaminants in the environment. Soil is a naturally occurring complex system composed of multiple components. Existing research on soil particle aggregation has predominantly focused on homo‐aggregation. However, the addition of biochar to soil inevitably induces hetero‐aggregation with soil components. In this study, the effects of biochar NPs on the aggregation of representative clay minerals (hematite and illite) and natural soil NPs from Luvisol, Phaeozem and Ferralsol under various solution chemistry were studied. The mechanisms were further elucidated by adopting the Derjaguin‐Landau‐Verwey‐Overbeek (DLVO) theory. The results indicated that the addition of negatively charged biochar NPs significantly altered the aggregation behaviours of positively charged hematite NPs through charge neutralisation. The aggregation of negatively charged illite particles was inhibited by the generating H‐bonding and steric repulsion. Biochar NPs significantly increased the colloidal stability of Luvisol (from 343.82 to 382.96 mM) and Ferralsol NPs (from 28.39 to 215.35 mM) by increasing the net DLVO repulsive forces. Nevertheless, the stability of Phaeozem NPs, containing higher organic matter, decreased with increasing biochar NP concentrations due to electrostatic shielding. In conclusion, for complicated natural soil systems with significant differences between organic and inorganic components, the application of biochar NPs has a profound impact on colloidal particle interactions, particularly affecting positively‐charged mineral colloids and soils with low soil organic matter content.

62. 题目: Towards Explainable AI: Interpreting Soil Organic Carbon Prediction Models Using a Learning‐Based Explanation Method
文章编号: N25031803
期刊: European Journal of Soil Science
作者: Nafiseh Kakhani, Ruhollah Taghizadeh‐Mehrjardi, Davoud Omarzadeh, Masahiro Ryo, Uta Heiden, Thomas Scholten
更新时间: 2025-03-18
摘要: An understanding of the key factors and processes influencing the variability of soil organic carbon (SOC) is essential for the development of effective policies aimed at enhancing carbon storage in soils to mitigate climate change. In recent years, complex computational approaches from the field of machine learning (ML) have been developed for modelling and mapping SOC in various ecosystems and over large areas. However, in order to understand the processes that account for SOC variability from ML models and to serve as a basis for new scientific discoveries, the predictions made by these data‐driven models must be accurately explained and interpreted. In this research, we introduce a novel explanation approach applicable to any ML model and investigate the significance of environmental features to explain SOC variability across Germany. The methodology employed in this study involves training multiple ML models using SOC content measurements from the LUCAS dataset and incorporating environmental features derived from Google Earth Engine (GEE) as explanatory variables. Thereafter, an explanation model is applied to elucidate what the ML models have learned about the relationship between environmental features and SOC content in a supervised manner. In our approach, a post hoc model is trained to estimate the contribution of specific inputs to the outputs of the trained ML models. The results of this study indicate that different classes of ML models rely on interpretable but distinct environmental features to explain SOC variability. Decision tree‐based models, such as random forest (RF) and gradient boosting, highlight the importance of topographic features. Conversely, soil chemical information, particularly pH, is crucial for the performance of neural networks and linear regression models. Therefore, interpreting data‐driven studies requires a carefully structured approach, guided by expert knowledge and a deep understanding of the models being analysed.

63. 题目: Molecular activity mediates the composition and assembly of dissolved organic matter in lake sediments
文章编号: N25031802
期刊: Limnology and Oceanography
作者: Shuailong Wen, Ang Hu, Francisco Dini‐Andreote, Lei Han, Shuyu Jiang, Kyoung‐Soon Jang, Jianjun Wang
更新时间: 2025-03-18
摘要: Lake sediments are hotspots for carbon transformation and burial, where the turnover of dissolved organic matter (DOM), influenced by molecular activity, regulates global carbon cycling. However, the composition of sediment DOM and how its assembly mechanisms are related to molecular activity remain poorly understood. Here, 63 freshwater sediments were collected from tropical to cold temperate climatic zones in China. We explored the molecular composition and assembly of sediment DOM and the underlying mechanisms driven by climate, physicochemical factors, and microbes along the gradient of molecular activity, indicated by the number of potential biochemical transformations in which a molecule is involved. Sediment DOM was dominated by lipid‐ (35%) and lignin‐like compounds (33%), and the latter were enriched as the molecular activity of DOM increased. Besides, the DOM assemblage with higher potential biochemical transformations had greater compositional similarity across different climatic zones and tended to assemble deterministically. Specifically, as the average number of potential biochemical transformations of molecules increased from 0.4 to 14, the assembly of these molecules was structured by a shift from stochastic to deterministic processes, with the latter accounting for ≥ 75% thereafter. Overall, DOM assemblages were primarily structured by physicochemical factors, including sediment total organic carbon and electrical conductivity. As molecular activity increased, however, assemblages were increasingly affected by climate and bacterial communities, consistent with the enhanced complexity of bacterial–molecular networks. Collectively, our study highlights that the turnover of DOM regulated by biotic and abiotic factors is further constrained by the intrinsic molecular activity.

64. 题目: Phosphorus fractions and their transformation in coupling with organic carbon cycling after seven-year manure application in subtropical soil
文章编号: N25031801
期刊: Soil and Tillage Research
作者: Jingjing Zhang, Jiaqing Huang, Jiong Wen, Zhi Peng, Nan Zhang, Yanan Wang, Yang Zhang, Shiming Su, Xibai Zeng
更新时间: 2025-03-18
摘要: Phosphorus (P) is a crucial macronutrient for crop yield. Repeated swine manure application can provide considerable amounts of P and organic carbon (C) for agricultural soils. However, a deeper understanding of the transformation of soil P fractions and their coupling with organic C cycling through chemical and biological processes is urgently needed to enhance P utilization efficiency and C sequestration. A seven-year swine manure application (SSMA) experiment was conducted at varying rates (0, 7.5, 15, 30, and 45 t·ha−1 per year) to investigate the changes in P fractions, the coupling of P and C transformation, and the driving factors in acidic soils. The results revealed that SSMA significantly increased soil total P, predominantly as inorganic P (Pi), whereas organic P (Po) exhibited a limited increase and plateaued at 15 t·ha−1 manure application. The 15–45 t·ha−1 manure treatments dramatically enhanced the nonstable P fractions, particularly pH- and Ca-induced Ca8-P; moreover, Ca8-P had a greater impact on Olsen-P than Fe-P and Al-P. SSMA promoted P mobilization by increasing alkaline phosphatase activity and the abundance of P-cycling functional genes. However, the primary factors directly affecting nonstable P fractions were the elevated soil pH and soil organic carbon (SOC). Additionally, nonstable P fractions were positively correlated with O-aryl-C and ketone-C components. Swine manure applications altered organic C components by stimulating SOC-driven enzyme activities involved in organic C degradation. Organic C components were also influenced by available P and N, primarily through the abundance of genes involved in organic C fixation rather than C degradation. Furthermore, 45 t·ha−1 SSMA treatment restricted the increase in the abundance of P-cycling genes, most C-cycling genes, and dominant bacteria harboring P-cycling genes. This study provides critical insights into the coupling transformation mechanisms of P and C and highlights that excessive swine manure application impairs functional bacterial growth and organic C storage in addition to increasing the risk of P loss in agricultural soils.

65. 题目: One- and two-step H2O activation of fungus bran for calcium-rich biochar in tar steam reforming
文章编号: N25031709
期刊: Journal of Environmental Chemical Engineering
作者: Shuai Guo, Shengqi Zhang, Tiankuo Guo, Shujun Zhu, Hongwei Qu, Xingcan Li, Jilin Tian
更新时间: 2025-03-17
摘要: Tar produced during thermal conversion is a harmful by-product. The catalytic conversion of tar represents an effective approach for the elimination of tar contaminants. Biochar is important in tar reforming owing to its porous structure, low cost, and catalytic potential. In this study, four activated carbon catalysts were produced for catalytic tar water vapor reforming using fungus bran as a precursor through water-washing pretreatment and one- and two-step H₂O activation. Catalysts obtained from water vapor activation had larger specific surface areas and more functional groups, especially catalysts obtained from two-step activation (i.e., largest specific surface area, S_BET=274.3 m²/g). Both the tar removal efficiency and catalyst’s gas yield increased with the increase in reforming temperature. Activated catalysts exhibited significant tar conversion, increased gas yield, H₂ selectivity, resistance to carbon buildup; and enhanced graphitization. Performance of the two-step activated catalysts was superior compared to that of one-step activation, with maximum tar conversion (88.8%) and gas yield (316 ml/g) achieved at 800 ℃. Tar conversion and reforming gas yields of the catalysts obtained from the water-washing pretreatment decreased, and the intensity of the diffraction peaks of Ca(OH)₂ substantially decreased in the x-ray diffraction (XRD) patterns of the catalysts after water washing, which removed calcium from the biomass and created a larger specific surface area and mesoporous structure during activation. In the in-situ tar H₂O reforming process, elemental calcium can be used as an active site on the surface of biochar for tar removal. Study findings demonstrated the positive role of tar reformation.

66. 题目: Seasonal Variations in Potable Water Quality of Bahawalpur City: A Comprehensive Assessment of Major Ions, Organic Matter, and Disinfection Byproducts
文章编号: N25031708
期刊: Environmental Monitoring and Assessment
作者: Sundas Kali, Mazhar Iqbal Zafar, Abida Farooqi, Muhammad Saifullah, Sajida Rasheed, Muhammad Bilal khan Niazi, Amir Waseem, Luiza C Campos
更新时间: 2025-03-17
摘要:

Industrialization and population explosion are ultimately affecting freshwater resources. Bahawalpur is a rapidly growing city in Pakistan where groundwater is the major source of drinking water. However, groundwater is also being contaminated due to various anthropogenic sources. To meet the need for clean drinking water, filtration plants have been installed throughout the city. To monitor the water quality index of the treated water, water samples were collected from the filtration plants installed by Tehsil Municipal Administration in Bahawalpur city. Different physicochemical parameters, major ions, organic matter, and disinfection byproducts (DBPs) were analysed. Both raw and chlorinated water in summer and winter season were investigated. Results revealed that all raw samples were biologically contaminated showing the presence of E. coli in all raw water samples, this justified the need for disinfection. Despite chlorination, several samples were still contaminated due to the lack of available residual chlorine in the distribution system. The carcinogenic Bromoform (27% samples) and dibromochloromethane (22% samples) surpassed the WHO permissible limits for drinking water in both seasons. Dichloroacetic acid exceeded the WHO permissible limits in 33% and 11% of samples during summer and winter, respectively. Overall, DBPs were higher during summer than winter season. Standard ultraviolet absorption at 254 nm (SUVA₂₅₄) showed that the source of organic matter was microbial except for Bohar gate and Islamic colony, where the source of water was surface water. Chlorination also affected the water chemistry in both seasons. The water quality index showed that the chlorinated water was fit for drinking in the winter season; however, 34% of samples were found unfit for drinking during summer. Monitoring of the DBPs is recommended on a regular basis, in addition to the organic matter removal from the water before chlorination. This study provides valuable information to achieve Sustainable Development Goal 6 which is for clean water and sanitation. So, this research can provide significant data to the policy makers to improve the water quality in developing countries like Pakistan.

67. 题目: Acidity impacts on microbial diversity and litter decomposition for organic soils
文章编号: N25031707
期刊: Plant and Soil
作者: Catharine M Pschenyckyj, Chris D Evans, Liz J Shaw, Robert I Griffiths, Michael C Bell, Jonathan P Ritson, Joanna M Clark
更新时间: 2025-03-17
摘要:

Background

Dissolved organic carbon (DOC) concentrations have increased in soil solutions and surface waters over the past 30 years in acid sensitive areas of Europe and Northern America. This has been linked to recovery from acidification of soils with decreasing levels of atmospheric pollution. Whilst previous research has found pH related DOC solubility is a likely driver of increased DOC concentrations in surface waters, it is unclear whether increased DOC production from organic matter decomposition, due to more favourable pH conditions for biological activity, has also contributed to the rising trends in surface waters.

Aim

We investigated how acidity impacts microbial communities, the decomposition of litter types common to acid-sensitive ecosystems, and the impact on DOC production.

Methods

A decomposition study using litter bags and the Tea Bag Index was incorporated into an established acidity manipulation field experiment across two sites with contrasting acid deposition histories, and two characteristic soil types (peats and peaty podzols).

Results

We found higher rates of litter decomposition in podzol soil than peat leading to higher DOC production and aromaticity, as indicated by absorbance properties. Acidity manipulations did not influence decomposition rates for most litter types, DOC production for any litter type, Tea Bag Index parameters (stabilisation factor and decomposition rate) or microbial diversity, for any site or soil type.

Conclusion

Our study suggests that decomposition of aboveground-collected litter does not mediate acidity effects on DOC production, whilst soil type, and physiochemical soil responses to acidity, are more influential on DOC release from organic soils.

68. 题目: Enclosure restoration regulates epiphytic microbial communities involved in carbon sequestration in a restored urban lake: A new insight from the stability of dissolved organic matter
文章编号: N25031706
期刊: Journal of Cleaner Production
作者: Siwen Hu, Dayong Zhao, Rujia He, Xiaojian Sun, Jin Zeng
更新时间: 2025-03-17
摘要: Microbial transformation of dissolved organic matter (DOM) critically regulates aquatic carbon sequestration through DOM stabilization. Submerged macrophyte enclosure restoration is considered an effective strategy for ameliorating eutrophic urban lakes; however, its effects on DOM biogeochemical stability and associated microbial drivers remain unclear. This investigation employed a multidisciplinary approach integrating DOM source tracking, molecular characterization, and leaf-epiphytic multitrophic microbiome analysis in a vegetated enclosure-restored urban lake. The results showed, compared to non-enclosure areas, enclosure areas exhibited enhanced DOM stability characterized by elevated aromaticity (SUVA₂₅₄: 70.9%), hydrophobicity (SUVA₂₆₀: 71.3%), and humification (HIX: 7.4%), coupled with 10.7% reduction of terrestrial anthropogenic input. FT-ICR MS analysis further uncovered a 2.9-fold enrichment in aromatic compounds (such as lignin and tannin) concomitant with depletion of labile compounds (lipids: 2.2% versus 8.2%; carbohydrates: 4.3% versus 12.3%) in enclosure compared to non-enclosure areas. Concurrently, enclosure restoration restructured epiphytic microbial communities and enriched functional microbes involved in C/N/S cycling processes, with Mantel test analysis demonstrating significant microbial-DOM covariation. Furthermore, reactomics analysis identified key enzymatic processes (such as dehydrogenation and functional group transfer) potentially driving DOM stabilization. Additionally, network analysis not only revealed distinct co-occurrence patterns of the epiphytic microbes and DOM properties but also showed stronger trophic interaction within the enclosure areas. These findings advanced empirical insights into DOM biogeochemistry and epiphytic microbial roles in driving DOM stabilization, providing novel linkages between aquatic carbon sequestration mechanisms and environmental engineering applications for urban lake restoration.

69. 题目: Shifts in organic matter character and microbial assemblages from glacial headwaters to downstream reaches in the Canadian Rocky Mountains
文章编号: N25031705
期刊: Biogeosciences
作者: Hayley F Drapeau, Suzanne E Tank, Maria A Cavaco, Jessica A Serbu, Vincent L St. Louis, Maya P Bhatia
更新时间: 2025-03-17
摘要: . Climate change is causing mountain glacial systems to warm rapidly, leading to increased water fluxes and concomitant export of glacially derived sediment and organic matter (OM). Glacial OM represents an aged but potentially bioavailable carbon pool that is compositionally distinct from OM found in non-glacially sourced waters. Despite this, the composition of riverine OM from glacial headwaters to downstream reaches and its possible role in structuring microbial assemblages have rarely been characterized in the Canadian Rockies. Over three summers (2019–2021), we collected samples before, during, and after glacial ice melt along stream transects ranging from 0 to 100 km downstream of glacial termini on the eastern slopes of the Canadian Rocky Mountains. We quantified dissolved and particulate organic carbon (DOC, POC) concentrations and used isotopes (Δ14C–OC, δ13C–OC) and dissolved OM (DOM) absorbance and fluorescence to assess OM age, source, and character. Environmental data were combined with microbial 16S rRNA gene sequencing to assess controls on the composition of stream water microbial assemblages. From glacial headwaters to downstream reaches, OM showed a clear transition from being aged and protein-like, with an apparent microbial source, to being relatively younger and humic-like. Indicator microbial species for headwater sites included chemolithoautotrophs and taxa known to harbour adaptations to cold temperatures and nutrient-poor conditions, suggesting some role of glacial seeding of microbial taxa to the headwaters of this connected riverine gradient. However, physical and chemical conditions (including water temperature; POC concentration; protein-like DOM; and deuterium excess, an indicator of water source) could only significantly explain ∼ 9 % of the observed variation in microbial assemblage structure. This finding, paired with the identification of a ubiquitous core microbial assemblage that comprised a small proportion of all identified amplicon sequence variants (ASVs) but was present in large relative abundance at all sites, suggests that mass effects (i.e., whereby high dispersal rates cause homogenization of adjacent communities) largely overcome species sorting to enable a connected microbial assemblage along this strong environmental gradient. Our findings suggest that a loss of novel glacial and microbial inputs with climate change, coupled with catchment terrestrialization, could change OM cycling and microbial assemblage structure across the evolving mountain-to-downstream continuum in glacierized systems.

70. 题目: Sedimentary organic carbon dynamics in a glaciated Arctic fjord: tracing contributions of terrestrial and marine sources in the context of Atlantification over recent centuries
文章编号: N25031704
期刊: Biogeosciences
作者: Dahae Kim, Jung-Hyun Kim, Youngkyu Ahn, Matthias Forwick, Seung-Il Nam
更新时间: 2025-03-17
摘要: . In this study, we investigated sedimentary organic carbon (OC) dynamics in Kongsfjorden, Svalbard, using three multicores collected during the HH22 and HH23 cruises aboard the RV Helmer Hanssen in 2022 and 2023. We assessed the relative contributions of petrogenic, soil-derived, plant-derived, and marine OC by applying a four-source apportionment approach based on Δ¹⁴C_org, δ¹³C_org, and lignin parameters, including the (Ad/Al)ᵥ ratio and lignin phenol concentrations, with Monte Carlo (MC) analysis. Age-depth models based on ²¹⁰Pb and ²²⁶Ra data were used to evaluate temporal variations in the accumulation rates (ARs) of sedimentary OC. Our findings revealed a significant increase in marine OC ARs in recent decades, which appears to be closely linked to enhanced Atlantic Water (AW) inflow. This trend suggests that changes in the fjord’s biogeochemical cycles, driven by AW, are influencing sedimentary OC dynamics. Consequently, the increasing influence of AW underscores the potential for ongoing Arctic warming to further amplify AW inflow into Arctic fjords, with significant implications for carbon cycling and fjord ecosystems. By providing a historical perspective on AW trends and their effects on sedimentary OC dynamics, this study offers valuable insights into the potential consequences of future climate change.

71. 题目: Grazing exclusion significantly reduced soil organic carbon stocks but enhanced soil inorganic carbon stocks in desert steppe of northwest China
文章编号: N25031703
期刊: Ecological Indicators
作者: Guangxing Zhao, Zhihao Zhang, Akash Tariq, Rapkat Sabit, Jordi Sardans, Corina Graciano, Xiangyi Li, Yuhe Zhu, Josep Peñuelas, Dhafer A Al-Bakre, Fanjiang Zeng
更新时间: 2025-03-17
摘要: Grazing exclusion is a crucial management practice impacting carbon sequestration and ecosystem stability. However, the effects and key factors of long-term grazing exclusion on soil organic carbon stocks (SOCS) and soil inorganic carbon stocks (SICS) in the desert steppe remain unexplored. To address this gap, we evaluated the impacts of different grazing exclusion periods (0, 6, 11, 16 years, GE0, GE6, GE11, GE16) on SOCS, SICS and soil total carbon stocks (STCS). Grazing exclusion reduced SOCS and mineral-associated organic carbon (MAOC) stocks but promoted SICS and STCS. GE6 exerted the most detrimental impact on the STCS in this region. SICS increased by 9.34 %, while SOCS decreased by 32.86 % after GE16. Specifically, SICS in the region were 9.36 to 12.26 times higher than SOCS. Overall, grazing exclusion led to an increasing in STCS by 3.27 Mg·ha−1, with SOCS decreasing by 1.04 Mg·ha−1 and SICS increasing by 4.31 Mg·ha−1. These findings suggested that SICS were substantially higher in arid zones and should be given special consideration in studies assessing environmental impacts on ecosystem C sequestration. Grazing exclusion was not effective in enhancing SOC stocks; instead, MAOC played a critical role in reducing SOC stocks. Mean annual precipitation (MAP) and aboveground biomass (AGB) were significant factors modulating SICS, while SOC and SIC directly influenced STCS, with environmental factors affecting STCS primarily through indirect pathways. This study highlights that grazing exclusion significantly reduced SOC stocks, elevated SIC stocks and explores the mechanisms impacting soil C sequestration.

72. 题目: Effects of reindeer grazing on thermal stability of organic matter in topsoil in Arctic tundra
文章编号: N25031702
期刊: Catena
作者: Ekaterina Filimonenko, Maria Uporova, Ekaterina Dimitryuk, Nataliya Samokhina, Tida Ge, Abeer S Aloufi, Nikolai Prikhodko, Yakov Kuzyakov, Andrey Soromotin
更新时间: 2025-03-17
摘要: Reindeer grazing is a geochemical factor of carbon (C) and nutrient cycling in high-latitude ecosystems. Reindeer consume and trample aboveground biomass, and return nutrients by urine and faces on soil surface. Degradation of vegetation cover due to overgrazing induces soil warming, decreases soil organic matter (SOM) content, and affects its stability. We investigated the effects of reindeer grazing on the thermal stability and temperature sensitivity (Q10) of SOM decomposition in the Gydan Arctic tundra. Thermogravimetric analysis of the topsoil (0–5 cm) from grazed and ungrazed tundra was used to divide SOM into three thermal pools – labile, stable, and persistent. The thermally labile pool contributed 62 % to SOM, reflecting large portion of partly decomposed plant litter. The thermal stability of SOM was evaluated by the temperature, at which the half of the organic matter was lost (T50), and by the activation energy of SOM combustion (Ea TG). Reindeer grazing increased the thermal stability of SOM in tundra by decrease in the thermally labile SOM content, as well as increase in T50 and Ea TG. The decrease in the labile SOM content in grazed compared to ungrazed tundra explained the reduction of soil microbial respiration at sites under reindeer grazing. The CO2 efflux from the ungrazed and grazed soils at increasing temperatures was used to investigate the Q10 of SOM decomposition. A 10 °C increase in soil temperature accelerated microbial SOM decomposition by 3.1 and 2.9 times in ungrazed and grazed tundra soils, respectively. Concluding, reindeer grazing in the Arctic tundra decreased SOM content in topsoil and increased the thermal stability of the remaining organic matter.

73. 题目: Nitrogen-fixing tree species enhance the positive effects of tree species richness on soil organic carbon sequestration by increasing fine root phosphorus loss
文章编号: N25031701
期刊: Catena
作者: Yanchun Liu, Qinglin Li, Huimin Tian, Shirong Liu, Chuang Ma, Menghan Wang, Hui Wang, Angang Ming
更新时间: 2025-03-17
摘要: Mixed planting of multiple tree species and introducing nitrogen (N)-fixing tree species have been regarded as the most effective methods to enhance the ecological function of planted forests. Although there is increasing concern about the effects of tree richness on litter decomposition, knowledge gap still exists about whether N-fixing tree species regulate the effect of tree richness on soil organic carbon (SOC) sequestration by changing fine root decomposition. A 9-year tree species richness experiment with four species gradients (1, 2, 4, and 6 species) interacted with N-fixing tree species was conducted in subtropical forests. Fine root decomposition rate and changes in SOC based on an in situ microcosm incubation were measured to determine the effects of tree species richness and N-fixing tree species on fine root decomposition and SOC storage. We found that tree species richness positively affected fine root C, N, and phosphorus (P) loss. Regardless of the effects of tree richness, the presence of N-fixing tree species enhanced P loss by 30.6%. The increased SOC induced by fine root decomposition showed a positive non-linear response to tree species richness. The presence of N-fixing trees amplified the promoting effects of tree species richness on the net accumulation of SOC by 54.6% probably attributed to the alleviated soil P limitation calculated by soil extracellular enzyme stoichiometry, due to the stimulated root P release and soil available P content. This study demonstrates that the presence of N-fixing tree species significantly enhances the positive effects of tree species richness on SOC storage in subtropical forests. This process is driven by the accelerated release of root P, which alleviates soil P limitation and promotes microbial activity. These findings underscore the critical role of N-fixing tree species in enhancing the ecological functionality of mixed plantations through improved nutrient cycling and C sequestration.

74. 题目: Terrestrial browning from Colored Dissolved Organic Matter (CDOM) changes the seasonal phenology of the coastal Arctic carbon cycle
文章编号: N25031611
期刊: Biogeosciences
作者: Clement Bertin, Vincent Le Fouest, Dustin Carroll, Stephanie Dutkiewicz, Dimitris Menemenlis, Atsushi Matsuoka, Manfredi Manizza, Charles E Miller
更新时间: 2025-03-16
摘要: . Arctic warming affects land-to-ocean fluxes of organic matter, with significant impacts on coastal ecosystems and air-sea CO₂ fluxes. In this study, we modify a regional ECCO-Darwin ocean biogeochemistry simulation of the Mackenzie River region to include riverine export of colored dissolved organic matter (CDOM) and its effect on light attenuation, marine carbon cycling, and water-column heating from UV-A to visible light absorption. We find that CDOM light attenuation triggers both a two-week delay in the seasonal phytoplankton bloom and an increase in sea-surface temperature (SST) by 1.7 °C. While the change in phytoplankton phenology has limited effect on air-sea CO₂ fluxes, the local increase in SST due to terrestrial browning switches the coastal zone from an annual sink of atmospheric CO₂ to a source (7.35 Gg C yr^-1). Our work suggests that the projected increase in terrestrial CDOM has strong implications for phytoplankton phenology and coastal air-sea carbon exchange in the Arctic.

75. 题目: Bed substrate influences leaf litter decomposition rates and leached dissolved organic matter quality in subsurface flow constructed wetlands
文章编号: N25031610
期刊: Science of the Total Environment
作者: Mercedes Guerrero-Brotons, Rosa Gómez, Anna M Romaní, Yolanda García-de Fuentes, María Isabel Arce
更新时间: 2025-03-16
摘要: Providing endogenous labile carbon (C) is crucial when designing constructed wetlands (CWs) to treat C-limited but nitrate rich-wastewater. In subsurface flow CWs, the main sources of C are the bed substrate and vegetation. When senescent plant leaves fall on the CW bed surfaces, they release C and nutrients during decomposition, fuelling microbial reactions and enhancing CW performance. However, the type of bed substrate not only influences plant and microbial growth but may also affect the chemical composition of leaves and their role as a C-source. To study this, we designed an experiment to analyze the effect of different bed substrates (gravel only, gravel + soil and gravel + biochar) on i) leaf litter decomposition rates and ii) the chemical quality and potential microbial uptake of leaf leachates. Our goal was to advance in the selection of a CW substrate that promotes leaf litter decomposition as a suitable and effective source of labile C for microorganisms. We observed varying decomposition rates among substrates, which appeared to result from differences in environmental conditions at the habitat scale rather than differences in leaf chemical composition. Photodegradation mechanisms dominated in gravel beds, driving decomposition at rates similar to those observed with soil addition, where microbial activity played a major role. In contrast, the addition of biochar inhibited decomposition. C leached from plants growing in soil and biochar substrates exhibited the highest microbial uptake, likely due to the presence of essential nutrients. This study supports that adding natural soil to gravel is the most favourable option for promoting labile C supply via plant decomposition, thereby enhancing microbial activity. Furthermore, our results suggest that management strategies allowing leaf litter to remain on CW bed surfaces would provide a valuable supply of DOC, helping to mitigate labile C limitation in the treatment of irrigated agricultural drainage water.

76. 题目: Recycled wheat straw biochar enhances nutrient-poor soil: Enzymatic kinetics of carbon, nitrogen, and phosphorus cycling
文章编号: N25031609
期刊: Journal of Environmental Management
作者: Qiuting Yan, Haixia Tian, Yi Huang, Xiangli Mu, Guangmu Tang, Haigang Ma, Mallavarapu Megharaj, Wanli Xu, Wenxiang He
更新时间: 2025-03-16
摘要: The recycling of waste wheat straw into biochar for soil improvement is a promising, sustainable strategy to enhancing nutrient-poor soils. Biochar application to soil has been shown to enhances the activity of key enzymes involved in nutrient cycling, such as invertase (INV), urease (URE), and alkaline phosphatase (ALP), which play roles in carbon (C), nitrogen (N), and phosphorus (P) cycling, as well as catalase (CAT), an enzyme with redox properties. However, the kinetic behavior of these enzymes remains largely unexplored. A 36-week laboratory study was conducted to evaluate the effects of biochar on enzyme kinetics in grey desert and aeolian soils including Michaelis–Menten constant (Km), maximum reaction velocity (Vmax), and catalytic efficiency (Vmax/Km). Results indicated that biochar application significantly increased soil pH, available phosphorus (AP), ammonium nitrogen (NH4+-N), dissolved organic carbon (DOC), and microbial biomass carbon (MBC) while reducing nitrate nitrogen (NO3−-N), which were identified as dominant factors influencing enzyme kinetic parameters. Enzyme activities related to C, N, and P cycling (excluding catalase) increased significantly at a biochar application rate of 4 % by mass. Changes in Km and Vmax for URE, INV, ALP, and CAT suggest that biochar influences enzyme kinetics through mechanisms such as adsorption, microenvironmental shifts, and allosteric modulation. An economic assessment identified 4 % biochar application as the optimal rate, yielding soil quality index (SQI) values of 0.53 and 0.65 for grey desert and aeolian soils, respectively. These findings suggest that biochar-amended soils exhibit improved fertility, highlighting the potential of biochar to enhance soil health.

77. 题目: Application of iron-modified biochar in the fields of adsorption and degradation of antibiotics
文章编号: N25031608
期刊: Journal of Environmental Management
作者: Xinru Yang, Xin Tian, Yanan Xue, Cuiping Wang
更新时间: 2025-03-16
摘要: Antibiotics, as emerging contaminants, have led to persistent global pollution issues, prompting long-standing attention on methods for their effective removal. Among various methods, iron-modified biochar stood out for its ability to adsorb and degrade antibiotics in the environment because biochar can provide a porous structure and oxygen-rich functional groups for efficient antibiotic adsorption, while the Fe2+/Fe3+ redox cycle in the iron modification biochar enhanced electronic transmission and further increased degradation. This review systematically summarized preparation methods of different iron-modified biochar, the adsorption capacities, mechanisms, and influencing factors of pollutants. It also explored the co-activation of iron and biochar, which enhanced the release of free radicals through Fenton-like oxidation pathways and accelerated degradation through photocatalytic electron-hole pair production. Additionally, the relationship between adsorption and degradation was discussed. Notably, an environmental risk assessment of iron-modified biochar and disposal of the used iron-modified biochar were discussed, which were critical for practical applications. Finally, the review highlighted the future directions of antibiotic pollution control and the broader potential of iron-modified biochar.

78. 题目: Assessing the methane mitigation potential of biochar and stover incorporation: Insights from the emission dynamics and soil microbiome in maize agroecosystems
文章编号: N25031607
期刊: Soil and Tillage Research
作者: Xu Yang, Jun Yuan, Yinghui Bi, Lidan Wang, Junqi Zhang, Chaoqun Wei, Xin Cui, Han Li, Peiyu Luo, Jun Meng, Wenfu Chen
更新时间: 2025-03-16
摘要: Methane (CH4), a significant greenhouse gas, plays a critical role in the global emission dynamics, with agricultural soils exerting dual action on its atmospheric levels. While the efficacy of biochar and stover incorporation in mitigating CH4 emissions in flooded soils is well-documented, their impact in upland systems, particularly within maize monocropping systems, has not been fully elucidated. This study presents a comprehensive analysis of the effects of biochar and stover incorporation on CH4 fluxes and the associated methanogenic and methanotrophic microbial communities in a maize monocropping system in Northeast China, over a five-year period. The field study was established with three treatments: untreated control (CK), maize stover incorporation at 7.5 t ha−1 yr−1 (MS), and biochar application at 2.63 t ha−1 yr−1 (MB). Soil CH4 fluxes, physical and chemical properties, and abundances of mcrA and pmoA genes were measured. Our findings indicated that MB and MS treatments effectively enhanced total CH4 uptakes during the study period compared to CK by 55.3 % and 84.4 %, respectively. Both MS and MB treatments significantly increased soil organic C (SOC), easily oxidizable C (EOC), and dissolved organic C (DOC) contents, with MS demonstrating a more pronounced boost. A shift in the microbial community, favoring methanotrophy, was indicated by a reduced mcrA/pmoA ratio and altered gene abundances of mcrA and pmoA in the MB and MS relative to the CK. Pearson’s correlation analysis did not find a significant relationship between DOC and soil water content (SWC) with CH4 emissions. The random forest (RF) model identified that pmoA, mcrA/pmoA, SOC, and mcrA were the top four determinants of CH4 emissions. This study underscores the potential of biochar and stover return as effective strategies for reducing agricultural CH4 emissions and emphasizes the necessity of elucidating the microbial underpinnings involved. Further research is warranted to refine these practices for diverse agricultural contexts and to evaluate their long-term environmental efficacy.

79. 题目: Green manure roots return drives saline-alkali soil organic carbon accumulation via microbial necromass formation
文章编号: N25031606
期刊: Soil and Tillage Research
作者: Fangdi Chang, Hongyuan Zhang, Peiyi Zhao, Na Zhao, Jiashen Song, Ru Yu, Jing Wang, Xiquan Wang, Dongxun Han, Xiaodong Liu, Jie Zhou, Yuyi Li
更新时间: 2025-03-16
摘要: Green manure strongly affects saline-alkali soil organic carbon (SOC) sequestration. The mechanism by which green manure influences the contribution of plant and microbial-derived carbon (C) to SOC in wheat-green manure cropping system remains unclear. Herein, plant residue C (PRC), microbial, bacterial, and fungal necromass C (MNC, BNC, and FNC), enzyme activity and microbial community were determined under wheat fallow after harvest (CK), green manure roots return (GMR), and green manure shoots and roots return (GMRS) in a five-year field experiment. Compared with CK, GMR and GMRS increased SOC content by 12 % and 11 % at 0–20 cm, respectively. Specifically, GMR accelerated the lignin biotransformation by increasing the relative abundance of K-strategy fungi, caused a reduction in the contribution of plant residues to SOC by 16–31 %. While GMR increased MNC, especially BNC by 1.6–2.8 times, which was the primary driver of SOC sequestration. Comparatively, GMRS increased the relative abundance of r-strategy bacteria by 12–13 %, and C- and N-acquisition enzymes by 12–17 % and 56–68 % compare to CK. This in turn, increased the accumulation of PRC, but decreased MNC (especially FNC) contribution to SOC. Overall, green manure return strategies altered the contribution of plant residues and microbial necromass to SOC by regulating microbial life strategies. MNC (especially FNC) contributed more to SOC than PRC. Therefore, green manure specially root return is a viable option to drive SOC accumulation via microbial necromass formation in wheat-green manure cropping system in saline-alkali soils.

80. 题目: Soil respiration and carbon sequestration response to short-term fertilization in wheat-maize cropping system in the North China Plain
文章编号: N25031605
期刊: Soil and Tillage Research
作者: Jian Zhang, Peikun Li, Lin Li, Mina Zhao, Peisen Yan, Yuan Liu, Wei Li, Shengyan Ding, Qinghe Zhao
更新时间: 2025-03-16
摘要: Fertilization significantly influences the soil physicochemical properties and crop growth in agricultural ecosystems, yet our understanding of its impact on soil respiration remains limited. To bridge this knowledge gap, we conducted a comprehensive study in the winter wheat-summer maize rotation system of the North China Plain. We examined the driving factors and processes governing soil respiration, and its temperature sensitivity (Q10), in response to various fertilization treatments, including an unfertilized control (CK), organic fertilizer (OM), organic fertilizer in combination with mineral fertilizer (OMNPK), and mineral fertilizer (NPK). Our findings revealed significant changes in Q10 values under different treatments. In maize, Q10 values increased by 4.4 % in OM, 19.9 % in OMNPK, and 15.5 % in NPK treatments. Conversely, in wheat, Q10 values decreased by 9.9 %, 9.6 %, and 7.7 % under OM, OMNPK, and NPK treatments, respectively. Fertilization led to a substantial increase in mean soil respiration of both maize (6.6 %-12.7 %) and wheat (10.1 %-21.3 %). Moreover, fertilization significantly enhanced crop yield, stem biomass, and root biomass. In maize, soil respiration exhibited a linear increase with rising soil pH value, ammonium nitrogen and available potassium content, and crop biomass. Similarly, wheat soil respiration showed a linear trend with increasing soil pH value, total phosphorus, and soil organic carbon content. Structural equation modeling highlighted key factors contributing to variations in soil respiration. For maize, available potassium content, soil temperature, soil water content, and crop height explained 89 % of the variation. In wheat, pH value, total phosphorus, and total potassium content, soil temperature, soil water content, crop height, and crop biomass collectively accounted for 93 % of the variation of soil respiration. Fertilizer application significantly enhanced crop yield and carbon emission efficiency, specifically in wheat. Fertilized plots exhibited carbon emission efficiency 0.78–2.06 times higher than unfertilized plots in wheat. Among all treatments, OMNPK treatment maintained high yield, carbon emission efficiency, and net carbon sequestration in wheat. In summary, during winter wheat cultivation in the North China Plain, the practice of organic fertilizer combined with mineral fertilizer emerges as a superior strategy. This approach not only sustains crop yields but also augments carbon sequestration in crops, demonstrating its significant potential for agricultural carbon management.