Abstract Rice paddies are a major anthropogenic source of atmospheric methane (CH₄), yet the spatial pattern and underlying mechanism of CH₄ emissions from rice paddies across climatic gradients remain poorly understood. We collected and incubated 30 flooded paddy soils spanning tropical to temperate regions of China, quantified CH₄ emissions and explored their soil and microbial drivers. We discovered that cumulative CH₄ emissions exhibited pronounced geographical variability, with higher emissions in tropical soils (0.18–10.75 mg kg−1) than in temperate soils (0.07–0.17 mg kg−1), and were primarily regulated by dissolved organic carbon (DOC), DOC accounted for 36.0% of the variance in cumulative CH₄ emissions. Peak CH₄ emission rates were jointly influenced by DOC and microbial biomass carbon, together they explained 24.4% of the variance in peak CH₄ emission rates. The timing of peak emissions was governed by the slow degradation of particulate organic carbon (POC), POC accounted for 13.8% of the variance in the timing of peak emissions. Structural equation modeling (SEM) further revealed that soil pH and mean annual temperature (MAT) could indirectly regulate cumulative CH₄ emissions through affecting the accumulation of labile carbon and nitrogen pool, the model explained 63% of the spatial variation in cumulative CH₄ emissions in total. The indirect effect of MAT was 0.20, and the indirect effect of soil pH was − 0.26. These results highlight the critical role of climate–soil-microbe interactions in shaping regional patterns of methane emissions from rice paddies and provide mechanistic insights for improving CH₄ emission predictions under future climate change.

CaCO3 recovery from rejected brine by CO2 mineralization is a promising pathway for simultaneous carbon emission mitigation and brine management, though its large-scale deployment is constrained by the substantial consumption of alkaline reagents. To overcome this barrier, bipolar membrane electrodialysis (BMED) can be integrated to regenerate alkaline using green electricity. However, the undesired precipitation of carbonates/ hydroxides inside the BMED module often causes severe performance deterioration and membrane scaling, limiting long-term operation. This study proposes a novel amino acid-promoted electrodialysis-carbonation process that simultaneously enables CO2 mineralization and CaCO3 recovery from brine, while preventing internal membrane scaling. Recyclable amino acids were employed to regulate the decalcification and CaCO3 precipitation behavior. Benefiting from their strong pH-buffering capacity, Ca2+ chelation ability, and promotion of CO2 absorption, amino acids effectively suppressed precipitation within the BMED cell and enhanced CO2 dissolution in an external carbonation reactor. This synergistic mechanism allowed continuous CaCO3 recovery alongside amino acid regeneration. System feasibility was systematically evaluated under different amino acid types, initial Ca2+ concentrations, amino acid concentrations, and current densities. The process achieved 100 % decalcification efficiency, 90 % carbonation efficiency, and a low energy consumption of 2.84 kWh/kg-CaCO3 under selected conditions (0.25 mol/L Ca2+, 0.5 mol/L glycine, 14 mA/cm2). Moreover, multicycle tests confirmed the stability of the integrated system over five consecutive runs, consistently yielding vaterite-phase CaCO3 with spherical morphology. Overall, this work demonstrates a new amino acid-enabled strategy to mitigate precipitation in BMED systems, paving the way for sustainable CO2 mineralization with high-value CaCO3 recovery and efficient brine management.

Variability in environmental conditions and agricultural practices significantly affect the medicinal quality of Bupleurum chinense DC. (ChaiHu). This study integrated 16S rDNA sequencing and UPLC-MS metabolomics to analyze rhizosphere soil microbiota and terpenoid profiles in ChaiHu samples from six geographically distinct regions with divergent cultivation methods and soil properties. Comprehensive soil physicochemical characterization was conducted in parallel. Metabolomic analysis identified 130 terpenoid metabolites, including 43 triterpene saponin, 34 sesquiterpenoids, 25 triterpene, 19 monoterpenoids, 8 diterpenoids and 1 terpene. The rhizosphere microbiome was dominated by beneficial genera Haliangium, Gaiella, Sphingomonas and Gemmatimonas. Notably, Gemmatimonas abundance showed significant positive correlations with total nitrogen (TN, r = 0.74), available nitrogen (AN, r = 0.92), and nitrate nitrogen (NO3-N, r = 0.64) levels. Multivariate analysis revealed nitrogen and potassium dynamics as critical determinants of ChaiHu quality. Furthermore, intercropping not only increased the abundance of beneficial bacteria but also reconfigured the saikosaponin profile, specifically by increasing the content of saikosaponins B2 and C while decreasing that of saikosaponins A and D, whereas monocropping promoted OTU diversity. These findings establish that rhizosphere microbiome composition and soil nutrient stoichiometry coordinately regulate ChaiHu quality, providing an agroecological framework for optimizing cultivation protocols of this medicinal species.

Delayed wound healing in infected wounds is primarily hindered by bacterial infections, posing significant physical and psychological burdens on patients. Exploring effective antimicrobial strategies is crucial for targeting bacterial infections and mitigating drug resistance. In this study, we developed biomimetic nanoparticles by loading the antimicrobial agent ergosterol onto Prussian blue nanoparticles (PB NPs) and encapsulating them with red blood cell membranes, which abbrieviated as RBC@PB-E. In vitro antimicrobial assays demonstrated that RBC@PB-E generated reactive oxygen species (ROS) and heat under near-infrared (NIR) irradiation, enhancing bacterial thermosensitivity and disrupting bacterial biofilms and cell membranes. Transcriptome analysis of infected wounds revealed that RBC@PB-E reduced the expression of inflammatory factors. In vivo studies showed that RBC@PB-E exhibited prolonged circulation and effectively accumulated at infection sites after intravenous injection. The photothermal effects of PB NPs combined with the membrane-disrupting capability of RBC@PB-E facilitated ergosterol penetration into bacteria under NIR irradiation. This resulted in excellent antibacterial efficacy in a MRSA wound infection model.In conclusion, the multifunctional photothermally activated antimicrobial nanoplatform RBC@PB-E provides a promising approach for combating bacterial infections and promoting wound healing.

Extracting lithium from salt lake brines is crucial to achieve sustainable development of lithium resources. However, it remains a major challenge to design nanochannels with efficient selectivity and fast transport for target ions. Here, inspired by biological membranes, we reported a Janus graphene oxide membrane (JGOM) with an asymmetric structure that exhibits diode‐like ion transport behavior and achieves high‐efficiency Li + /Mg 2 ⁺ separation for lithium extraction applications. During the forward transport of ions, the nGO nanochannels modified by sulfonate groups (SO 3 − ) with precise size provide hopping recognition sites and additional electrostatic attraction for the fast transport of Li + , while imposed Mg 2+ dehydration and exposure to a stronger positive charge. The continuous pGO nanochannels modified by amino groups (NH 3 + ) further prevent the passage of dehydrated Mg 2+ by enhanced electrostatic repulsion while allowing Li + to transfer. Under the synergy of the two nanochannels, the JGOM demonstrates robust Li + /Mg 2+ separation performance, outperforming symmetrical structure GO membranes and other reported membranes, which was further confirmed by simulation results. This study provides a new insight into the rational design of ion sieving membranes.

With a growing global population and increasing demand for protein, soy protein may replace animal protein in the future because it is sustainably produced and has a balanced composition of essential amino acids. However, pure soy protein hydrogels have many problems, such as insufficient mechanical properties, which limit the application of soy protein hydrogels in the food field. This article aims to summarize and prospect the gel formation mechanism, gel properties, and applications of soy protein-based protein composites in food. The simple and effective method of protein compositing can improve the gel properties of soy protein. Depending on the specific needs, a suitable gel preparation method is selected to realize the wide application of composite soy protein gel systems in the food industry. In addition, research should continue to explore its combination with high technology to maximize the value of protein. At the same time, it is also important to pay attention to the shortcomings of odor and allergenicity in soy protein, as well as the limitations of the current composites with other proteins to minimize the drawbacks of soy protein and maximize the utilization of protein resources to meet the demand for protein.

Rice paddies are a major anthropogenic source of methane and a key target for reducing emissions of the greenhouse gas to the atmosphere. The delicate equilibrium between the production and oxidation of methane in paddy soils is shaped largely by the abundances and compositions of different microbial communities within the soil ecosystem and the interactions between them. Ammonium addition can alleviate nitrogen deficiency for methanotrophs, but ammonium can also inhibit their growth when present in excess. However, the threshold concentration for this switch is not currently known. Here we report the results of a nine-day laboratory incubation experiment that sought to examine the effects of increasing ammonium concentrations on methane oxidation in rice paddy soil at refined concentration intervals. We measured methane oxidation rates and analysed the gene abundances and community compositions of methanotrophs and ammonia oxidizers in the incubated soils to decode interactions between these communities. Our results showed that an ammonium concentration of 10 mg NH4+$$ {\mathrm{NH}}_4<^>{+} $$-N d.w.s stimulated methane oxidation, but concentrations above 30 mg NH4+$$ {\mathrm{NH}}_4<^>{+} $$-N kg-1 d.w.s inhibited the oxidation rate. At the lower ammonium concentration, type Ia methanotrophs appeared to outcompete ammonia oxidizers for nitrogen; however, this was reversed at higher concentration where the proliferation of ammonia oxidizers was stimulated. We show how ammonium stimulated the ammonia-oxidizing bacteria (AOB) to a greater extent than ammonia-oxidizing archaea (AOA), but with much smaller changes in the specific AOB community composition, when compared to the AOA communities. Our findings highlight ammonium concentration as a key factor regulating the interaction between methanotrophs and ammonia oxidizers in paddy soils and identify the threshold where ammonium shifts from promoting to inhibiting methane oxidation.

Ammonia (NH3) volatilization has garnered significant concern owing to its detrimental environmental impact. Yet, the specific characteristics of NH3 volatilization and its associated microbial activity in response to various fertilizer management strategies in acidic soils remain poorly understood. To address this gap, we conducted a five-year field observation experiment by applying urea alone, as well as in combination with organic fertilizer (rapeseed cake or Vicia), to explore the effect of soil organic matter (SOM) mineralization on NH3 volatilization and to elucidate the contribution of ammonia oxidizers to NH3 volatilization in the acidic soil. The results revealed that the combined application of organic fertilizers and urea (ranging from 0.63 to 7.81 kg ha- 1) reduced NH3 volatilization compared with applying urea alone (ranging from 2.6 to 13.02 kg ha- 1). Vicia mulching was shown to be more effective in reducing NH3 loss. NH3 volatilization was positively regulated by CO2 emissions. Initially, organic fertilizers applications facilitated SOM mineralization, thereby enhancing NH3 volatilization during the first year. However, after five years of sustained application of these fertilizers, SOM mineralization became suppressed, consequently lowering the cumulative NH3 volatilization. Moreover, NH3 volatilization exhibited a significant negative correlation with the nitrification potential of ammonia-oxidizing bacteria (AOB), which became more abundant after organic fertilizer application. Our results underscore the suppressive effect of organic fertilizer application on NH3 volatilization through the reduction of SOM mineralization. Furthermore, it was elucidated that AOB was the primary drivers of nitrification, regulating the conversion of NH3 to NO3 - in the acidic soil.

Biochar application to amend acidified tobacco-soils can enhance tobacco quality and reduce nitrous oxide (N2O) emissions. Microplastics from agricultural mulch are commonly found in cash-crop farmland soils and, together with biochar, affect soil N2O emissions. In this study, we applied three types of microplastics (polyethylene, PE; polylactic acid, PLA; polybutylene adipate terephthalate, PBAT) and rice biochar alone or in combination to acidified tobacco planting soil in central China to investigate their effects on soil N2O emissions, soil chemical properties, nitrogen-cycle-related functional genes, and microbial functional diversity during a 35-day laboratory incubation period. Significant increases in N2O emissions were observed with PE and PLA, which raised emissions by 15.96 % and 21.52 %, respectively. Additionally, different microplastics affected soil N2O emissions through distinct regulatory pathways. Co-application of microplastics and biochar suppressed N2O emissions compared to microplastics alone. Biochar mitigates N2O emissions mainly by increasing the abundance of the nosZ gene. It can remediate soil contaminated by microplastics and reduce their negative impacts on the soil environment. This study provides deeper insight into the effects of microplastics on soil nitrogen cycling and biochar-mitigated remediation of microplastic-contaminated soil.

Nitrate-dependent Fe-oxidizing bacteria (NFeOB) are key mediators for carbon (C) and nitrogen (N) cycling in paddy soils. The aim of this study was to explore soil NFeOB community in response to addition of readily available organic C in different soils. The present study used glucose (Glu) and acetate (Ace) as carbon source for anaerobic enrichment cultures of NFeOB from two soils (Danyang (DY) and Qichun (QC)) establishing four treatments: DY-Ace, DY-Glu, QC-Ace, and QC-Glu. Cumulative N 2 O emissions from QC soil were 3.06 µg/L in Ace and 2.04 µg/L in Glu treatment. N 2 O emissions in DY soil were 65.79 µg/L with Glu treatment and 1.92 µg/L with Ace treatment. CO 2 emissions showed a strong uptake trend and were almost at the same level (mean 139.70 mg/L) for the two different carbon sources. High-throughput sequencing showed that the carbon source was the controlling factor for the microbial abundance and diversity. Simpson and Shannon–Wiener indices indicated higher abundance and diversity in the Ace treatment than that of Glu treatment. Proteobacteria was dominant in all treatments, and at genus level, Cupriavidus was the most abundant. Moreover, higher abundance of Actinobacteria in the DY-Glu treatment resulted in higher N 2 O emissions. In short, nitrate-dependent Fe(II) oxidation by Cupriavidus is imperative for CO 2 fixation.

Soil organic carbon (SOC) is the key indicator of soil fertility, and its stabilization plays a significant role in terrestrial carbon cycling. The turnover of SOC often interacts with iron due to its active redox characteristics, especially in paddy soils. Zero-valent iron (ZVI) is highly reductive, while how its addition controls SOC turning over in soil received less attention and knowledge gap exists on soil C dynamics. Therefore, we investigated the influence of ZVI addition on soil and straw C dynamics in submerged soil over a period of 30 days in an incubation study. The results showed that ZVI addition enhanced the endogenous Fe(III) reduction, and the exogenous ZVI was oxidized mostly to Fe(II), resulting in substantial Fe(II) accumulation, with the content 33.39-164.9% higher than that in non-ZVI treatments after incubation. At the initial stage of incubation during day 0-10, ZVI addition showed a stimulated effect on OC accumulation as both the cumulative CO2 emission and dissolved organic carbon (DOC) released were reduced in ZVI-amended treatments. This could be attributed to the O2 limitation on OC mineralization caused by the lower oxidation-reduction potential (ORP) by ZVI addition. Besides, endogenous Fe(III) reduction boosted by ZVI addition could release fresh surfaces on Fe mineral for C accumulation by forming organics-Fe mineral complexes. During the latter stage of day 10-30, ZVI addition showed an inhibited effect on OC accumulation as both the cumulative CO2 emission and DOC released were increased in ZVI-amended treatments, and CH4 emission was vigorous after a 10-day lag phase. Labile OC was liberated and vulnerable to decomposition by microorganisms due to the dissolution of OC-Fe(III) oxide complexes as Fe(III) reduction was enhanced by ZVI addition. Furthermore, CH4 emission was promoted by ZVI addition through lowering soil ORP and supplying electrons for methanogenesis. ZVI addition mitigated OC decomposition during the initial stage and stimulated that during the latter stage of incubation. Overall, ZVI addition increased straw C accumulation in the form of insoluble carbon (Caccumulated), but the different responses of C dynamic between days 0-10 and 10-30 led to a statistic insignificant positive effect. However, the association between iron oxides and OC was enhanced in ZVI addition treatments due to the anaerobic corrosion of ZVI, which may increase the stability of OC, indicating a potential to accumulate more straw C in the long term.

Paddy fields serve as significant sources of methane (CH4) emissions. The periodic flooding and draining in paddy soils induce alternating redox processes, leading to iron transformations and further influencing the production and oxidation of CH4. However, the relationships between CH4 production/oxidation and the concentrations/forms of iron oxides in rice paddies across different regions are largely unknown. Here we collected 26 paddy soil samples from various regions spanning from North to South China. We show that the CH4 production potential varies from 0.005 to 0.618 mg kg−1 d−1, which exhibits an overall trend of higher values in the south and lower values in the north. Moreover, the CH4 oxidation potential spans from 0.888 to 57.384 mg kg−1 d−1, showing no significant latitudinal trend. Highly weathered soils exhibit higher CH4 production potentials, mainly due to the high content of free iron oxides and the low reactivity of aged iron minerals. This hinders the protection of organic carbon (OC) by iron minerals, therefore increasing substrate availability for methanogenesis. In addition to the direct effect, iron forms also indirectly influence CH4 production and oxidation potentials by affecting soil pH, OC availability, and CH4-related microbial abundances. The coefficients of the indirect effect of iron forms on CH4 production and oxidation potential are 0.44 and 0.26, respectively, which are larger than that of the direct effects. Our research reveals the pivotal role of various iron forms in controlling CH4 production and oxidation processes in paddy soils, helping to expand the understanding of the effect of iron biogeochemistry on CH4 emissions in paddy soils and offering new perspectives for mitigating agricultural greenhouse gas emissions.

Seasonal variations in agricultural land cover patterns and their spatial scale effects on surface water nitrogen (N) and phosphorus (P) concentrations in watersheds have been major concerns. Understanding the relationships between land cover metrics and pond nutrients are of great significance to enhance water contamination prediction efficiencies and guide land use planning in agricultural watersheds. In this context, the present study aims to investigate the seasonal variations in the N and P concentrations in 28 ponds in a developed agricultural watershed in central China in 2019. Multivariate statistical analyses were applied to assess the relationships of the pond water N and P concentrations with multi-scale land cover patterns. Besides the pond water ammonium nitrogen (NH4+-N) concentrations, the total nitrogen (TN), nitrate nitrogen (NO3--N), total phosphorus (TP), and dissolved phosphorus (DP) concentrations in the investigated ponds were higher in summer than those observed in other seasons. The hierarchical partitioning model results demonstrated a spatial consistency in scale effects of land cover metrics on the pond hydrochemical parameters in the different seasons. Redundancy analysis (RDA) showed that the land cover patterns better predicted the variations in the pond water N and P concentrations at the 100 m buffer zone scale in spring and summer, as well as at the 50 m buffer zone scale in fall and winter. Among the land cover metrics considered in this study, the orchard area proportion (POR), landscape shape index (LSI), and largest patch index (LPI) showed the highest significant correlations with the pond water N and P concentrations. The results of this study provide valuable information for effective land use management to control pond water pollution and promote sustainable development in agricultural watersheds.

The role of iron (Fe) in soil organic matter (SOM) stabilization and decomposition in paddy soils has recently gained attention, but the underlying mechanisms during flooding and drying periods remain elusive. As the depth water layer is maintained in the fallow season, there will be more soluble Fe than during the wet and drainage seasons and the availability of oxygen (O2) will be different. To assess the influence of soluble Fe on SOM mineralization during flooding, an incubation experiment was designed under oxic and anoxic flooding conditions, with and without Fe(III) addition. The results showed that Fe(III) addition significantly (p < 0.05) decreased SOM mineralization by 14.4 % under oxic flooding conditions over 16 days. Under anoxic flooding incubation, Fe(III) addition significantly (p < 0.05) decreased 10.8 % SOM decomposition, mainly by 43.6 % methane (CH4) emission, while no difference in carbon dioxide (CO2) emission was noticed. These findings suggest that implementing appropriate water management strategies in paddy soils, considering the roles of Fe under both oxic and anoxic flooding conditions, can contribute to SOM preservation and mitigation of CH4 emissions.

Additives were widely investigated to retain the nutrients and mitigate the greenhouse gas emissions (GHGs) during manure composting. However, the sustained effects of additives on the GHGs emissions following incorporation of composts to soil were scarcely explored. This study evaluated the effects of bentonite added at the beginning of pig manure composting on the GHGs emissions during two successive processes, i.e., composting and soil incubation amended with composting products. Addition of bentonite did not hinder the composting process and alter the total CO2 emission. On the other hand, reduction by about 17% and 29% for CH4 and N2O emission, respectively, was achieved in the presence of bentonite during composting. Incorporation of the final composting products to soil enhanced significantly the soil C and N of various forms, and gas emissions of CO2 and N2O. However, no significant differences were observed between bentonite-manure co-compost and manure-only compost application except for the N2O emission. Compared to the manure-only compost, compost amended with bentonite reduced N2O loss by around 6.8%, but not statistically significant. This study confirmed that addition of bentonite at the composting stage can mitigate the GHGs emission considering both composting and compost application stages, with all reductions occurring at the composting stage.

The maturity degree of organic fertilizer affects its application effect, but this application effect difference and the underlying reasons for it remain largely unclear. This study explored the effects of cattle manure compost with different maturities on soybean yield, soil physicochemical properties, and biological properties, and the underlying reasons for the differences in the application effects of organic fertilizers with different maturities. The results showed that the T21d treatment (GI = 62.5%, germination index) had the optimal effect on increasing soybean yield, and its effect on improving basic soil physicochemical properties, active organic matter components, enzyme activity, and microbial diversity was the most obvious. Compared with the control (CK), the soybean yield was increased by 15.1% under T21d treatment, and the soil organic matter (OM), alkali-hydrolyzed nitrogen (AN), available phosphorus (AP), and available potassium (AK) contents were increased by 29.9%, 25.0%, 22.2%, and 8.4%, respectively; the dissolved organic matter (DOM), extractable humus (HE), humic acid (HA), and fulvic acid (FA) contents in the soil were increased by 96.5%, 22.6%, 16.7%, and 30.6%, respectively; and the activities of soil phosphatase, neutral protease, urease, and cellulase were increased by 45.4%, 164.1%, 33.9%, and 128.9%, respectively. However, the fertilizer efficiency under the T28d, T45d, and T60d treatments with high-maturity organic fertilizers was lower than that under T21d. In general, the appropriate maturity of organic fertilizers has a positive effect on soil improvement and yield increase, but the excessive maturity of organic fertilizers reduces their application effects.

During ferrihydrite formation, Al 3+ or Cr 3+ hinders the formation of μ-oxo dimers but promotes the conversion of μ-oxo dimer to dihydroxo dimer and the creation of crystal growth sites.