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Humic substance (HS)-ferric iron (Fe(III)) coprecipitates are widespread organo-mineral associations in soils and aquifers and have the capacity to immobilize and detoxify Cr(VI). These coprecipitates undergo transformation owing to their thermodynamic instability; however, the effects of this transformation on their environmental behaviors remain unclear, particularly in aerobic environments. In this study, the aerobic transformation of humic acid (HA)-Fe(III) coprecipitates, a representative of HS-Fe(III) coprecipitates, was simulated. The environmental effect was then evaluated after conducting an adsorption-reduction batch experiment toward Cr(VI). The aerobic transformation characteristics, as well as the adsorption/reduction capacity of HA-Fe(III) coprecipitates, were found to depend strongly on their structures. In ferrihydrite (Fh)-like coprecipitates, amorphous Fh is readily transformed into crystalline hematite and goethite at aerobic environments, leading to a much lower specific surface area and adsorption capacity. However, this increasing degree of crystallization enhanced the inductive reduction ability towards Cr(VI) owing to the more significant shift of electron pairs in the FeOC bond toward the HA direction. In HS-like coprecipitates, Fe(III) always serves as a cation bridge connecting HA molecules, but can be reduced to Fe(II) by the associated HA after aerobic transformation. The produced Fe(II), therefore, drove the reduction of the adsorbed Cr(VI). These findings emphasize the pivotal role of aerobic transformation in enhancing the reduction capacity for Cr(VI), which opens a new avenue for the development of in-situ remediation agents for Cr(VI)-contaminated sites.
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Extrusion has been proven to be a novel approach for modifying the physicochemical characteristic of Baijiu vinasses (BV) to extract polysaccharides, contributing to the sustainable development of brewing industry. However, the comparison of the bioactivity and bioavailability of extruded (EX) and unextruded (UE) BV polysaccharides was unclear, which impended the determination of the efficacy of extrusion in BV resourcing. In this study, in vitro digestion and fecal fermentation experiments were conducted to investigate the bioavailability, and the results showed that EX exhibited less variation in the monosaccharide composition and molecular weight, while exhibiting a stronger antioxidant capacity compared to UE. Moreover, during fermentation EX increased the abundance of Parasutterella and Lachnospiraceae, while UE promoted the proliferation of Bacteroides, Faecalibacterium, and Dialister, resulting in variation in short-chain fatty acids. These findings indicate that extrusion can enhance the capacity of antioxidants and bioavailability of BV polysaccharides.
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Antioxidantes , Disponibilidade Biológica , Fezes , Fermentação , Polissacarídeos , Antioxidantes/farmacocinética , Antioxidantes/farmacologia , Antioxidantes/química , Polissacarídeos/química , Fezes/química , Fezes/microbiologia , Digestão , Ácidos Graxos Voláteis/metabolismo , Microbioma Gastrointestinal/efeitos dos fármacos , Monossacarídeos , HumanosRESUMO
The wide microplastics (MPs) occurrence affects soil physicochemical and biological properties, thereby influencing its carbon cycling and storage. However, the regulation effect of MPs on soil organic carbon (SOC) formation and stabilization remains unclear, hindering the accurate prediction of carbon sequestration in future global changes under continuous MP pollution. Phospholipid fatty acids, amino sugars and lignin phenols were used in this study as biomarkers for microbial community composition, microbial necromass and plant lignin components, respectively, and their responses to conventional (polyethylene; PE) and biodegradable (polylactic acid; PLA) MPs were explored. Results showed PLA MPs had positive effects on soil microbial biomass, while the positive and negative effects of PE MPs on microbial biomass varied with MP concentration. PE and PLA MPs increased microbial necromass contents and their contribution to SOC, mainly due to the increase in fungal necromass. On the contrary, PE and PLA MPs reduced lignin phenols and their contribution to SOC, mainly owing to the reduction in vanillyl-type phenols. The response of microbial necromass to PLA MPs was higher than that to PE MPs, whereas the response of lignin phenols was the opposite. MPs increased SOC level, with 83%-200% and 50%-75% of additional SOC in PE and PLA treatments, respectively, originating from microbial necromass carbon. This finding indicates that the increase in SOC pool in the presence of MPs can be attributed to soil microbial necromass carbon, and MPs increased capacity and efficacy of microbial carbon pump by increasing microbial turnover and reducing microbial N limitation. Moreover, the increase in amino sugars to lignin phenols ratio in PE treatment was higher than that in PLA treatment, and the increase in SOC content in PLA treatment was higher than that in PE treatment, indicating a high possibility of SOC storage owing to PLA MPs.
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Carbono , Lignina , Microplásticos , Poliésteres , Polietileno , Microbiologia do Solo , Poluentes do Solo , Solo , Lignina/metabolismo , Poliésteres/metabolismo , Poluentes do Solo/metabolismo , Solo/química , PlantasRESUMO
Numerous investigations have illuminated the profound impact of phosphate on the adsorption of uranium, however, the effect of phosphate-mediated surface modification on the reactivity of zero-valent iron (ZVI) remained enigmatic. In this study, a phosphate-modified ZVI (P-ZVIbm) was prepared with a facile ball milling strategy, and compared with ZVIbm, the U(VI) removal amount (435.2 mg/g) and efficiency (3.52×10-3 g·mg-1·min-1) of P-ZVIbm were disclosed nearly 2.0 and 54 times larger than those of ZVIbm respectively. The identification of products revealed that the adsorption mechanism dominated the removal process for ZVIbm, while the reactive modified layer strengthened both the adsorption pattern and reduction performance on P-ZVIbm. DFT calculation result demonstrated that the binding configuration shifted from bidentate binuclear to multidentate configuration, further shortening the Fe-U atomic distance. More importantly, the electron transferred is more accessible through the surface phosphate layer, and selectively donated to U(VI), accounting for the elevated reduction performance of P-ZVIbm. This investigation explicitly underscores the critical role of ZVI's surface microenvironment in the domain of radioactive metal ion mitigation and introduces a novel methodology to amplify the sequestration of U(VI) from aqueous environments.
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Ferro , Fosfatos , Ferro/química , Fosfatos/química , Adsorção , Urânio/químicaRESUMO
Composting presents a viable management solution for lignocellulose-rich municipal solid waste. However, our understanding about the microbial metabolic mechanisms involved in the biodegradation of lignocellulose, particularly in industrial-scale composting plants, remains limited. This study employed metaproteomics to compare the impact of upgrading from aerated static pile (ASP) to agitated bed (AB) systems on physicochemical parameters, lignocellulose biodegradation, and microbial metabolic pathways during large-scale biowaste composting process, marking the first investigation of its kind. The degradation rates of lignocellulose including cellulose, hemicellulose, and lignin were significantly higher in AB (8.21%-32.54%, 10.21%-39.41%, and 6.21%-26.78%) than those (5.72%-23.15%, 7.01%-33.26%, and 4.79%-19.76%) in ASP at three thermal stages, respectively. The AB system in comparison to ASP increased the carbohydrate-active enzymes (CAZymes) abundance and production of the three essential enzymes required for lignocellulose decomposition involving a mixture of bacteria and fungi (i.e., Actinobacteria, Bacilli, Sordariomycetes and Eurotiomycetes). Conversely, ASP primarily produced exoglucanase and ß-glucosidase via fungi (i.e., Ascomycota). Moreover, AB effectively mitigated microbial stress caused by acetic acid accumulation by regulating the key enzymes involved in acetate conversion, including acetyl-coenzyme A synthetase and acetate kinase. Overall, the AB upgraded from ASP facilitated the lignocellulose degradation and fostered more diverse functional microbial communities in large-scale composting. Our findings offer a valuable scientific basis to guide the engineering feasibility and environmental sustainability for large-scale industrial composting plants for treating lignocellulose-rich waste. These findings have important implications for establishing green sustainable development models (e.g., a circular economy based on material recovery) and for achieving sustainable development goals.
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Biodegradação Ambiental , Compostagem , Lignina , Lignina/metabolismo , Compostagem/métodos , Microbiologia do Solo , Bactérias/metabolismo , Eliminação de Resíduos/métodosRESUMO
The characteristics of dissolved organic matter (DOM) serve as indicators of nitrate pollution in groundwater. However, the specific DOM components associated with nitrate in groundwater systems remain unclear. In this study, dual isotopes of nitrate, three-dimensional Excitation emission matrices (EEMs) and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) were utilized to uncover the sources of nitrate and their associations with DOM characteristics. The predominant nitrate in the targeted aquifer was derived from soil organic nitrogen (mean 46.0%) and manure &sewage (mean 34.3%). The DOM in nitrate-contaminated groundwater (nitrate-nitrogen >20 mg/L) exhibited evident exogenous characteristics, with a bioavailable content 2.58 times greater than that of uncontaminated groundwater. Regarding the molecular characteristics, DOM molecules characterized by CHO + 3N, featuring lower molecular weights and H/C ratios, indicated potential for mineralization, while CHONS formulas indicated the exogenous features, providing the potential for accurate traceability. These findings provided insights at the molecular level into the characterization of DOM in nitrate-contaminated groundwater and offer scientific guidance for decision-making regarding the remediation of groundwater nitrate pollution.
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Monitoramento Ambiental , Água Subterrânea , Nitratos , Poluentes Químicos da Água , Água Subterrânea/química , Nitratos/análise , Poluentes Químicos da Água/análise , Monitoramento Ambiental/métodosRESUMO
Wastewater irrigation is used to supplement agricultural irrigation because of its benefits and freshwater resource scarcity. However, whether wastewater irrigation for many years affects the electron transfer capacity (ETC) of natural organic matter in soil remains unclear, and organic matter could influence the decomposition and mineralization of substances with redox characteristics in soil through electron transfer, ultimately affecting the soil environment. The composition of soil humic substances (HS) is highly complex, and the effects of soil humic acid (HA) and fulvic acid (FA) on ETC is poorly understood. In this study, we separately evaluated the responses of the electron-accepting capacity (EAC) and electron-donating capacity (EDC) of soil HA and FA in agricultural fields to various durations of wastewater irrigation. Results showed that the EAC of HA and FA increased significantly with increasing the duration of wastewater irrigation. When wastewater irrigation lasted for 56 years, the EAC of HA showed a higher increment (590 %) than that of FA (223 %). The EDC of soil HA and FA, conversely, decreased compared to the control, with the highest reduction of 35.6 % for HA and 65.9 % for FA. Specifically, the EDC of HA gradually decreased starting from 29 years of wastewater irrigation, whereas the decrease in the EDC of FA exhibited no clear pattern in relation to the duration of wastewater irrigation. Increased soil organic matter and total nitrogen content under long-term wastewater irrigation led to an increase in sucrase and phosphatase activities, along with an increase in EAC and a decrease in EDC of HS. This suggests that soil enzyme activities may ultimately lead to changes in ETC. The results of this research provide practical insights into the redox system in soil and its driving role in soil organic matter transformation and nutrient cycling under wastewater irrigation.
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The organic matter molecular mechanism by which combined hydrothermal carbonization (co-HTC) of municipal sludge (MS) and agricultural wastes (rice husk, spent mushroom substrate, and wheat straw) reduces the inhibitory effects of aqueous phase (AP) products on pak choi (Brassica campestris L.) growth compared to HTC of MS alone is not clear. Fourier-transform ion cyclotron resonance mass spectrometry was used to characterize the differences in organic matter at the molecular level between AP from MS HTC alone (AP-MS) and AP from co-HTC of MS and agricultural waste (co-Aps). The results showed that N-bearing molecules of AP-MS and co-Aps account for 70.6 % and 54.2 %-64.1 % of all molecules, respectively. Lignins were present in the highest proportion (56.3 %-78.5 %) in all APs, followed by proteins and lipids. The dry weight of co-APs hydroponically grown pak choi was 31.6 %-47.6 % higher than that of the AP-MS. Molecules that were poorly saturated and with low aromaticity were preferentially consumed during hydroponic treatment. Molecules present before and after hydroponics were defined as resistant molecules; molecules present before hydroponics but absent after hydroponics were defined as removed molecules; and molecules absent before hydroponics but present after hydroponics were defined as produced molecules. Large lignin molecules were broken down into more unsaturated molecules, but lignins were the most commonly resistant, removed, and produced molecules. Correlation analysis revealed that N- or S-bearing molecules were phytotoxic in the AP. Tannins positively influenced the growth of pak choi. These results provide new insights into potential implementation strategies for liquid fertilizers produced from AP arising from HTC of MS and agricultural wastes.
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Agricultura , Esgotos , Agricultura/métodos , Brassica/crescimento & desenvolvimento , Eliminação de Resíduos Líquidos/métodosRESUMO
Dissolved organic matter (DOM) plays a crucial role in driving biogeochemical processes and determining water quality in shallow groundwater systems, where DOM could be susceptible to dynamic influences of surface water influx. This study employed fluorescence excitation-emission matrix (EEM) spectroscopy combined with principal component coefficients, parallel factor analysis (PARAFAC), co-occurrence network analysis and structural equation modeling (SEM) to examine changes of DOM fractions from surface water to shallow groundwater in a mesoscale lowland river basin. Combining stable isotope and hydrochemical parameters, except for surface water (SW), two groups of groundwater samples were defined, namely, deeply influenced by surface water (IGW) and groundwater nearly non-influenced by surface water (UGW), which were 50.34 % and 19.39 % recharged by surface water, respectively. According to principal component coefficients, reassembled EEM data of these categories highlighted variations of the tyrosine-like peak in DOM. EEMs coupled with PARAFAC extracted five components (C1-C5), i.e. C1, protein-like substances, C2 and C4, humic-like substances, and C3 and C5, microbial-related substances. The abundance of the protein-like was SW > IGW > UGW, while the order of the humic-like was opposite. The bacterial communities exhibited an obvious cluster across three regions, which hinted their sensitivity to variations in environmental conditions. Based on co-occurrence, SW represented the highest connectivity between bacterial OTUs and DOM fractions, followed by IGW and UGW. SEM revealed that microbial activities increased bioavailability of the humic-like in the SW and IGW, whereas microbial compositions promoted the evolution of humic-like substances in the UGW. Generally, these results could be conducive to discern dissimilarity in DOM fractions across surface water and shallow groundwater, and further trace their interactions in the river watershed.
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Água Subterrânea , Rios , Água Subterrânea/química , Rios/microbiologia , Rios/química , Microbiota , Monitoramento Ambiental , Análise de Componente Principal , Substâncias Húmicas/análiseRESUMO
Lithium is an emerging strategic resource for modern energy transformation toward electrification and decarbonization. However, current mainstream direct lithium extraction technology via adsorption suffers from sluggish kinetics and intensive water usage, especially in arid/semiarid and cold salt-lake regions (natural land brines). Herein, an efficient proof-of-concept integrated solar microevaporator system is developed to realize synergetic solar-enhanced lithium recovery and water footprint management from hypersaline salt-lake brines. The 98% solar energy harvesting efficiency of the solar microevaporator system, elevating its local temperature, greatly promotes the endothermic Li+ extraction process and solar steam generation. Benefiting from the photothermal effect, enhanced water flux, and enriched local Li+ supply in nanoconfined space, a double-enhanced Li+ recovery capacity was delivered (increase from 12.4 to 28.7 mg g-1) under one sun, and adsorption kinetics rate (saturated within 6 h) also reached twice of that at 280 K (salt-lake temperature). Additionally, the self-assembly rotation feature endows the microevaporator system with distinct self-cleaning desalination ability, achieving near 100% water recovery from hypersaline brines for further self-sufficient Li+ elution. Outdoor comprehensive solar-powered experiment verified the feasibility of basically stable lithium recovery ability (>8 mg g-1) directly from natural hypersaline salt-lake brines with self-sustaining water recycling for Li+ elution (440 m3 water recovery per ton Li2CO3). This work offers an integrated solution for sustainable lithium recovery with near zero water/carbon consumption toward carbon neutrality.
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Humus, an important fraction of soil organic matter, play an environmental role on nutrients, organic and inorganic pollutants in riparian zones of urbanized rivers. In this study, dynamic variation process of humus fractions from riparian soils was revealed along Puhe River. Composite soil samples of four depths were collected from four land-uses, i.e., eco-conservation area (ECA), industrial area (INA), urban/town area (UTA), rural/agricultural area (RAA). Based on synchronous fluorescence spectra coupled with Gaussian band fitting, fulvic/humic acid predominantly contained tyrosine-like (TYLF), tryptophan-like (TRLF), microbial-like (MLF), fulvic-like (FLF) and humic-like (HLF) substances within each soil profile. TRLF, MLF and FLF (89.43-90.30 %) are the representative components in fulvic-acid, while MLF and HLF (52.81-59.97 %) in humic-acid. Phenolic, carboxylic and humified materials were present in both humus. According to 2-dimensitonal correlation spectroscopy and canonical correlation analysis, fulvic/humic acid within the ECA soil profile could be mainly derived from the degradations of terrestrial plant metabolites and residuals. Within the INA, fulvic-acid could be associated with treated/untreated wastewater, which entered the river and flew into the riparian during high flow period; whereas humic-acid could be relative to the terrestrials. Fulvic-acid had the same source as humic-acid in the UTA, which might be concerned with scattered domestic sewage and livestock wastewater, rather than the fluvial water. Furthermore, the source of fulvic/humic acid in the RAA was the crop metabolites and residuals, apart from the livestock wastewater. Noticeably, the variations of humus fractions in the ECA and RAA roughly occurred in 0-60 cm, while approximately in 20-80 cm in the INA and UTA. This proved that humus fractions in the former were referred to the plant/crop residuals, whereas humus fractions in the latter were those the terrestrials and fluvial water. This study could provide a key support for the construction and restoration of the urbanized riparian zone.
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Landfilling is a globally prevalent method for managing municipal solid waste disposal. Nonetheless, the potential for serious contamination and the significant regional disparities in the leachate produced pose varying degrees of risks to groundwater quality. Previous studies have focused on a single landfill or the same geo-climatic conditions, with a limited number of samples having resulted in a narrow distribution of landfill age and scale, which prevents the description of the pattern of change in landfill age and scale. As well as the effect of this change on the contaminants in the landfill leachate and surrounding groundwater is still unclear. Therefore, we sampled and analyzed leachate and surrounding groundwater from 62 landfills with different landfill ages, scales, and operating conditions in a region with dense and varied topography and climate. Aim to explore the effects of different landfill ages, scales, and operating conditions on contaminants in leachate and surrounding groundwater. Findings indicate that pollutant profiles in different media are influenced by the age, scale, and operational status of the landfill, and the impact of leachate on pollutant types and concentrations in groundwater is limited. A significant correlation exists between the concentration of contaminants in the groundwater affected by leaching from the impermeable layer and the age and scale of the landfill when compared to the leachate. The contamination potentials posed by different pollutants vary across environmental media. Total dissolved solids and NH4+-N in leachate presented high contamination potentials, whereas elemental metalloids (Mn, Al, Ba, and Fe) in the surrounding groundwater posed high environmental concerns. These insights furnish new avenues for monitoring, identification, and safeguarding against pollutants in landfills and proximate groundwater, which is imperative for the sustainable management of municipal waste.
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Experimental scale and sampling precision are the main factors limiting the accuracy of migration and transformation assessments of complex petroleum-based contaminants in groundwater. In this study, a mesoscale indoor aquifer device with high environmental fidelity and monitoring accuracy was constructed, in which dissolved toluene and trichloroethylene were used as typical contaminants in a 1.5-year contaminant migration experiment. The process was divided into five stages, namely, pristine, injection, accumulation, decrease, and recovery, and characteristics such as differences in contaminant migration, the responsiveness of environmental factors, and changes in microbial communities were investigated. The results demonstrated that the mutual dissolution properties of the contaminants increased the spread of the plume and confirmed that toluene possessed greater mobility and natural attenuation than trichloroethylene. Attenuation of the contaminant plume proceeded through aerobic degradation, nitrate reduction, and sulfate reduction phases, accompanied by negative feedback from characteristic ion concentrations, dissolved oxygen content, the oxidation-reduction potential and microbial community structure of the groundwater. This research evaluated the migration and transformation characteristics of typical petroleum-based pollutants, revealed the response mechanism of the ecosystem to pollutant, provided a theoretical basis for predicting pollutant migration and formulating control strategies.
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Livestock manure is often contaminated with heavy metals (HMs) and HM resistance genes (HMRGs), which pollute the environment. In this study, we aimed to investigate the effects of the aqueous phase (AP) produced by hydrothermal carbonization (HTC) of sewage sludge (SS) alone and the AP produced by co-HTC of rice husk (RH) and SS (RH-SS) on humification, HM bioavailability, and HMRGs during chicken manure composting. RH-SS and SS increased the humic acid content of the compost products by 18.3 % and 9.7 %, respectively, and significantly increased the humification index (P < 0.05) compared to the CK (addition of tap water). The passivation of HMs (Zn, Cu, As, Pb, and Cr) increased by 12.17-23.36 % and 9.74-15.95 % for RH-SS and SS, respectively, compared with that for CK. RH-SS and SS reduced the HMRG abundance in composted products by 22.29 % and 15.07 %, respectively. The partial least squares path modeling results showed that SS and RH-SS promoted compost humification while simultaneously altering the bacterial community and reducing the bioavailability of metals and host abundance of HMRGs, which has a direct inhibitory effect on the production and distribution of HMRGs. These findings support a new strategy to reduce the environmental risk of HMs and HMRGs in livestock manure utilization.
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Galinhas , Compostagem , Esterco , Metais Pesados , Esgotos , Animais , Metais Pesados/toxicidade , Substâncias Húmicas/análise , Carbono/química , Poluentes do Solo/toxicidade , Oryza/metabolismoRESUMO
The productivity and efficiency of two-chamber microbial electrolysis cell and anaerobic digestion integrated system (MEC-AD) were promoted by a complex of anaerobic granular sludge and iron oxides (Fe-AnGS) as inoculum. Results showed that MEC-AD with Fe-AnGS achieved biogas upgrading with a 23%-29% increase in the energy recovery rate of external circuit current and a 26%-31% decrease in volatile fatty acids. The energy recovery rate of MEC-AD remained at 52%-57%, indicating a stable operation performance. The selectively enriched methanogens and electroactive bacteria resulted in dominant hydrogenotrophic and acetoclastic methanogenesis in the cathode and anode chambers. Mechanistic analysis revealed that MEC-AD with Fe-AnGS led to specifically upregulated enzymes related to energy metabolism and electron transfer. Fe-AnGS as inoculum could improve the long-term operation performance of MEC-AD. Consequently, this study provides an efficient strategy for biogas upgrading in MEC-AD.
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Biocombustíveis , Eletrólise , Metano , Anaerobiose , Metano/metabolismo , Ácidos Graxos Voláteis/metabolismo , Esgotos/microbiologia , Fontes de Energia Bioelétrica/microbiologia , Reatores Biológicos , Eletrodos , Bactérias/metabolismoRESUMO
Landfills remain the predominant means of solid waste management worldwide. Widespread distribution and significant stockpiles of waste in landfills make them a significant source of methane emissions, exacerbating climate change. Anaerobic oxidation of methane (AOM) has been shown to play a critical role in mitigating methane emissions on a global scale. The rich methane and electron acceptor environment in landfills provide the necessary reaction conditions for AOM, making it a potentially low-cost and effective strategy for reducing methane emissions in landfills. However, compared to other anaerobic habitats, research on AOM in landfill environments is scarce, and there is a lack of analysis on the potential application of AOM in different zones of landfills. Therefore, this review summarizes the existing knowledge on AOM and its occurrence in landfills, analyzes the possibility of AOM occurrence in different zones of landfills, discusses its potential applications, and explores the challenges and future research directions for AOM in landfill management. The identification of research gaps and future directions outlined in this review encourages further investigation and advancement in the field of AOM, paving the way for more effective waste stabilization, greenhouse gas reduction, and pollutant mitigation strategies in landfills.
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Sulfamethazine (SAT) is widely present in sediment, soil, rivers, and groundwater. Unfortunately, traditional water treatment technologies are inefficient at eliminating SAT from contaminated water. Therefore, developing an effective and ecologically friendly treatment procedure to effectively remove SAT is critical. This has raised concerns about its potential impact on the environment and human health. In this study, metal-organic-inorganic composites consisting of graphene-encapsulated Fe-Mn metal catalyst (Mn3Fe1-NC) were synthesized by calcining MnFe Prussian blue analogs (PBA) under a nitrogen atmosphere. The composites were applied to activate peroxymonosulfate (PMS) and facilitate the degradation of SAT in aquatic environments. The Mn3Fe1-NC, dosed with 5 mg, in combination with PMS, dosed with 1.5 mmol L-1, achieved a 91.8% degradation efficiency of SAT. The transformation of the CN skeleton led to the formation of a carbon shell structure, which consequently reduced metal ion leaching from the material. At various pH levels, the iron and manganese ions were observed to leach out at levels lower than 0.1392 and 0.0580 mg L-1, respectively. In contrast, the Mn3Fe1-NC was found to be minimally impacted by pH levels and coexisting ions present in the aqueous environment. Radical burst experiments and electrochemical analysis tests verified that degradation primarily occurs through the nonradical pathway of electron transfer. The active sites responsible for this process were identified as the Mn (IV) and graphitic-N atoms on the material, which facilitate direct electron transfer. Additionally, the presence of Fe atoms promotes the valence cycling of Mn atoms. This study introduces new insights into the reaction mechanism and the constitutive relationship of catalytic centers in nonradical oxidation reactions.