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In order to investigate the effect of coal spontaneous combustion (CSC) gases such as CO, C2H4, C2H6, C3H8, C2H2, and H2 on the laminar burning velocity (LBV) of the CH4/air premixed flame, a constant volume chamber and a high-speed camera were used to measure the LBV of a 90% (in vol) CH4 and 10% CSC gas mixed fuel at an initial temperature of 300 K and over a wide equivalence ratio range from 0.7 to 1.3. Results show that the addition of all the CSC gases increases the LBV of CH4. Among all CSC gases, the CH4/C2H2 mixed fuel has the highest LBV, and the CH4/CO mixed fuel has the lowest LBV. With the addition of three typical stages of CSC gases, the LBV of CH4 was significantly enhanced. Based on the reaction path, mole fraction, and rate of production analysis, it is found that the addition of CSC gases in Stage 2 can increase the concentration of C2H5 and the consumption rate in the CH3–C2H6–C2H5 path, which is different from Stages 1 and 3. In addition, all the concentrations of H, O, and OH free radicals increase with the addition of three typical stages of CSC gases. [ABSTRACT FROM AUTHOR]

ZnO nanoparticles functionalized with APTES were obtained to evaluate their CH4 and CO2 adsorption at 298 K in a range between 0 and 10 bar. First, ZnO nanoparticles were obtained by a precipitation method and subsequently coated with (3-aminopropyl)triethoxysilane (APTES). As a preliminary study, the results were compared with previously reported naked nanoparticles in order to evaluate the influence of APTES coating on CO2 selectivity. UV-Vis, FT-IR spectroscopy, TGA, XRD, TEM/EDX, XPS and N2 adsorption at 77 K were used to characterize the evaluated material. It was observed that the amount of gas adsorbed on the surface of the nanostructure was very small in comparison with other materials traditionally used for this purpose but slightly higher than those obtained in naked nanoparticles evaluated in previous studies. The affinity of CO2 for the amines groups of the APTES ligand was also discussed. [ABSTRACT FROM AUTHOR]

Headwater wetlands are important sites for carbon storage and emissions. While local- and landscape-scale factors are known to influence wetland carbon biogeochemistry, the spatial and temporal heterogeneity of these factors limits our predictive understanding of wetland carbon dynamics. To address this issue, we examined relationships between carbon dioxide (CO2) and methane (CH4) concentrations with wetland hydrogeomorphology, water level, and biogeochemical conditions. We sampled water chemistry and dissolved gases (CO2 and CH4) and monitored continuous water level at 20 wetlands and co-located upland wells in the Delmarva Peninsula, Maryland, every 1–3 months for 2 years. We also obtained wetland hydrogeomorphologic metrics at maximum inundation (area, perimeter, and volume). Wetlands in our study were supersaturated with CO2 (mean = 315 μM) and CH4 (mean = 15 μM), highlighting their potential role as carbon sources to the atmosphere. Spatial and temporal variability in CO2 and CH4 concentrations was high, particularly for CH4, and both gases were more spatially variable than temporally. We found that groundwater is a potential source of CO2 in wetlands and CO2 decreases with increased water level. In contrast, CH4 concentrations appear to be related to substrate and nutrient availability and to drying patterns over a longer temporal scale. At the landscape scale, wetlands with higher perimeter:area ratios and wetlands with higher height above the nearest drainage had higher CO2 and CH4 concentrations. Understanding the variability of CO2 and CH4 in wetlands, and how these might change with changing environmental conditions and across different wetland types, is critical to understanding the current and future role of wetlands in the global carbon cycle. [ABSTRACT FROM AUTHOR]

Multi‐electron involved photoreduction of CO2 to hydrocarbon fuels is a long‐standing challenge, particularly in manipulating the selectivity of the target products. Here, a novel Ag–Pt bimetallic alloy on Zn‐based supports by photo‐deposition is designed for photocatalytic CO2 reduction to CH4 without any additives. This photocatalyst exhibits ≈ 98.9% selectivity for CH4. Experimental and theoretical calculations demonstrated that the excellent performance of the photocatalyst can be attributed to the localized surface plasmon resonance effect of metals, as well as the synergistic effects of the bimetallic sites. These factors are found to be beneficial not only for capturing solar radiation and facilitating electron migration but also for promoting the adsorption and activation of CO2 and the protonation of *CO. As a result, the photocatalyst achieved high selectivity and activity of photoreduction of CO2 to CH4. This work provides insights into the design of photocatalysts with highly selective target products for CO2 reduction. [ABSTRACT FROM AUTHOR]

In the last 40 years, inductively coupled plasma quadrupole (q) mass spectrometry (ICP‐qMS) has been recognized as one of the best tools for the quantification of multiple elements/isotopes and even the biomolecules they labeled in a homogeneous solution sample. However, it meets a tough challenge when acquiring multi‐m/z signals from an intact single‐cell dispersed in a cell suspension, since the single‐cell ion cloud generated in ICP presents an intermittently transient event with a duration time of hundreds of microseconds while the dwell time plus settling time of the q is at the similar time scale when peak‐hopping between different m/z. Herein, we report CH4 is able to stretch the single‐cell ion cloud duration time to more than 7,000 μs in collision‐reaction‐cell (CRC), allowing multi‐m/z signals acquisition by ICP‐qMS. Quantification of single‐cell's multiple phenotype protein markers can thus be achieved on ICP‐(CH4‐CRC)‐qMS, not only revealing the heterogeneity between the single cells but also enabling an unambiguous cell‐classification of their subtypes. CH4‐driven ion cloud‐stretched approach breaks through the long‐standing bottleneck limited single‐cell multiplex analysis on ICP‐qMS, paving a path for more important applications of ICP‐qMS in the fields related to single‐cell analysis. [ABSTRACT FROM AUTHOR]

Inland waters are important sources of the greenhouse gases carbon dioxide (CO2) and methane (CH4). Ponds have amongst the highest CO2 and CH4 fluxes of all aquatic ecosystems, yet seasonal variation in fluxes remain poorly characterized, creating challenges for accurately estimating annual emissions. Further, ponds can exhibit a range of mixing regimes, yet the impact of mixing regimes on gas emissions remains unclear. Here, we assessed annual dynamics of CO2 and CH4 in four temperate ponds (Minnesota, USA) that varied in mixing regimes. The ponds ranged from annual sinks to sources of CO2 (−1 to 15 mol m−2 yr−1) and were all significant sources of CH4 (4.3–8.2 mol m−2 yr−1), with annual fluxes in CO2 equivalents of 1.8–4.1 kg CO2-eq. m−2 yr−1. Mixing regimes impacted CO2 and CH4 dynamics, as stratified periods were associated with more anoxia, greater accumulation of gases in the bottom waters, higher emissions of CH4, and lower fluxes of CO2. Ponds with stronger summer stratification also had increased CO2 and CH4 fluxes associated with fall turnover. Overall, the two ponds with the strongest stratification had higher annual fluxes (2.6, 4.1 kg CO2-eq. m−2 yr−1) compared to the two ponds that more frequently mixed (1.8, 2.2 kg CO2-eq. m−2 yr−1). [ABSTRACT FROM AUTHOR]

The hydrogenation of magnesite to CH 4 and MgO offers a powerful approach for CO 2 direct utilization. To deepen the understanding of the reaction mechanisms, (Mg 5 (CO 3) 4 (OH) 2 (H 2 O) 4 was selected as a model compound to gain insights into carbonate hydrogenation. A novel Ni/Fe/ZrO 2 catalyst with ferromagnetic properties was employed to facilitate the magnetic separation of the catalyst from the solid products. Thermodynamic simulation and experiments were conducted to address key issues such as gas evolution during catalytic hydrogenation, the effects of catalyst on CH 4 selectivity, and the separation of solid products and catalyst. The results indicate that lower temperatures favor CH 4 formation, whereas higher temperatures favor CO formation. Increasing Ni loading can enhance the CH 4 selectivity. With the presence of 10Ni/Fe/ZrO 2 catalyst, 100% CH 4 selectivity can be achieved at 300 °C. Moreover, 10Ni/Fe/ZrO 2 catalyst exhibits high magnetic responsiveness, facilitating the solid separation and the recycle of the catalyst. • A novel route for the hydrogenation of magnesite to produce CH 4 and MgO is proposed. • A ferromagnetic Ni/Fe/ZrO 2 catalyst enables efficient separation of the catalyst and product. • Low temperature favors CH 4 formation, while high temperature favors CO formation. • 100% CH 4 selectivity can be achieved at 300 °C with the presence of 10Ni/Fe/ZrO 2. [ABSTRACT FROM AUTHOR]

To investigate the migration and transformation of greenhouse gases across soil layers, we examined the impact of fertilization on greenhouse gas emissions from the 0 to 40 cm soil layers in a subtropical Chinese fir plantation. Additionally, we identified the dominant factors regulating greenhouse gas emissions from various soil layers. Our findings revealed that forest soil acted as both a source of CO2 and N2O and a sink for CH4. As soil depth increased, both CO2 and N2O emissions decreased, along with CH4 absorption. Specifically, the CO2 and N2O emissions and CH4 absorption from the 0 to 10 cm soil layer were 1. 3-, 2. 5-, and 3. 3-fold greater than those from the 30 to 40 cm layer, respectively. Fertilization significantly reduced soil CO2 emissions and CH4 uptake in each layer (P＜0. 05) . Compared with those of the unfertilized treatment, fertilization led to a substantial decrease in soil CO2 emissions (approximately 56. 7%-77. 5%) and CH4 absorption (approximately 30. 4%-57. 8%) . Notably, the inhibitory effect of fertilization on these gases was most pronounced in the 30-40 cm and 20-40 cm soil layers. Furthermore, N2O emissions decreased significantly in the 10-30 cm soil layers due to fertilization (P＜0. 05), with the most obvious effect observed in the 10-20 cm layer. Overall, fertilization primarily reduced soil CO2 and N2O emissions and CH4 uptake by increasing soil moisture content. [ABSTRACT FROM AUTHOR]

Low-temperature methane (CH 4) gas sensors with high performance have garnered substantial interest due to their potential to reliably monitor CH 4 and achieve intrinsic safety. In this work, we explored strategies that combine photo-activation with bimetallic decoration. ZnO, Au/ZnO, Ag/ZnO and bimetallic AuAg/ZnO microspheres were synthesized to evaluate their CH 4 sensing capabilities and were characterized using various techniques. The synthesized samples exhibited hollow structures and favourable optical properties. Their sensing performance was assessed at room temperature under 365 nm ultraviolet (UV) illumination. Among these, the AuAg/ZnO microspheres demonstrated superior CH 4 sensing performance, characterized by low detection temperature (room temperature), a high-response value (62.61–5000 ppm CH 4) and a rapid response time (5 s). Furthermore, the response of AuAg/ZnO exceeded that of Au/ZnO (42.29), Ag/ZnO (36.37) and pure ZnO (12.52), being five times higher than that of pure ZnO. The enhanced gas-sensing performance can likely be attributed to the UV light and the synergistic effects of the bimetallic AuAg. This study provides insights into the development of high-performance, room-temperature CH 4 sensors. [ABSTRACT FROM AUTHOR]

To eliminate the harm of nitrogen oxides to human health and ecological environment, selective catalytic denitrification using methane as a reducing agent (CH4-SCR) has received widespread attention. Developing highly active CH4-SCR denitrification catalysts has become a research focus of this technology. In this article, Co(x)/ZRP catalysts were prepared by impregnation method, and the effects of Co(x)/ZRP catalysts with different cobalt loading amounts on the denitrification performance of CH4-SCR were investigated. The physicochemical properties of Co (x)/ZRP catalysts were characterized using XRD, H2-TPR, Py-IR, NH3-TPD and NO-TPD methods. The CH4-SCR denitrification performance of Co(x)/ZRP catalysts was evaluated on fixed bed micro-reactor under atmospheric pressure. The results showed that the cobalt species in the Co(x)/ZRP catalyst were Co3O4. With the increase of cobalt loading, the Co3O4 grains became larger, the redox ability and NO adsorption and desorption performance of the catalyst were improved. With the increase of cobalt loading, the denitrification activity of Co(x)/ZRP catalyst first increased and then decreased, which was consistent with the variation of medium strong acid amount in the total acid of the catalyst. Among them, the Co(20)/ZRP catalyst had a higher amount of medium strong acid, and the CH4-SCR denitrification performance was good, with Tm of 342 °C, XNomax of 39.2%. The L-acid and medium strong acid content of the catalyst played an important role in the CH4-SCR catalytic denitrification activity of the catalyst. [ABSTRACT FROM AUTHOR]

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Infrared thermography may be an alternative technology for measuring the amount of CH4 produced and has the advantages of low cost, speed and efficiency in obtaining results. The study’s objective was to determine if the infrared thermography is adequate for predicting the emission of CH4 in hair sheep and the best time after feeding to carry out the measurement. Twelve Santa Inês lambs (females, non-pregnant, with twelve months old and mean body weight of 39.3 ± 2.1 kg) remained for two days in respirometric chambers, in a semi-closed system, to determine the CH4 production. The animals were divided into two treatments, according to the diet provided. During this period, seven thermographic photographs were taken, at times − 1 h, -0.5 h, 0 h, 0.5 h, 1 h, 2 h, 3 h, 5 h, and 7 h, according to the feeding time, defined as 0 h. CH4 production was measured over 24 h. Thermographic images measured the maximum, minimum, average and point temperatures at the left and right flanks. The temperature difference between the left and right flanks (left minus right) was calculated each time. Pearson correlation coefficients, multiple regression and principal component analysis were carried out in SAS®. The best prediction of emission intensity of CH4 (kg of CH4 per dry matter intake) was obtained at 3 h after feeding: CH4/DMI = 13.9016–0,38673 * DifP2 + 3.39089 * DifMed2 (R² = 0.48), using the difference between left and right flanks for point and average temperature measures. Therefore, infrared thermography can be used as an indicator of CH4 production in hair sheep three hours after feeding. [ABSTRACT FROM AUTHOR]

Methane is one of the main components of automobile exhaust and has 25 times higher greenhouse effect than CO2. Methane is difficult to be purified by three-way catalyst (TWC) because of its stable chemical property. However lean / rich lambda oscillation improves methane purification rate. In this study we clarified CO, NO, and H2O in the exhaust and CeZr oxide in catalyst play a crucial role in improving the methane purification rate under lambda oscillation. [ABSTRACT FROM AUTHOR]

Background: Fire models have used pyrolysis data from oxidising and non-oxidising environments for flaming combustion. In wildland fires pyrolysis, flaming and smouldering combustion typically occur in an oxidising environment (the atmosphere). Aims: Using compositional data analysis methods, determine if the composition of pyrolysis gases measured in non-oxidising and ambient (oxidising) atmospheric conditions were similar. Methods: Permanent gases and tars were measured in a fuel-rich (non-oxidising) environment in a flat flame burner (FFB). Permanent and light hydrocarbon gases were measured for the same fuels heated by a fire flame in ambient atmospheric conditions (oxidising environment). Log-ratio balances of the measured gases common to both environments (CO, CO2, CH4, H2, C6H6O (phenol), and other gases) were examined by principal components analysis (PCA), canonical discriminant analysis (CDA) and permutational multivariate analysis of variance (PERMANOVA). Key results: Mean composition changed between the non-oxidising and ambient atmosphere samples. PCA showed that flat flame burner (FFB) samples were tightly clustered and distinct from the ambient atmosphere samples. CDA found that the difference between environments was defined by the CO-CO2 log-ratio balance. PERMANOVA and pairwise comparisons found FFB samples differed from the ambient atmosphere samples which did not differ from each other. Conclusion: Relative composition of these pyrolysis gases differed between the oxidising and non-oxidising environments. This comparison was one of the first comparisons made between bench-scale and field scale pyrolysis measurements using compositional data analysis. Implications: These results indicate the need for more fundamental research on the early time-dependent pyrolysis of vegetation in the presence of oxygen. Composition of pyrolysis gases measured in non-oxidising and ambient atmospheric conditions has been compared using compositional data analysis. Mean compositions changed between the non-oxidising and ambient atmosphere samples. These results indicate the need for more fundamental research on the early time-dependent pyrolysis of vegetation in the presence of oxygen. [ABSTRACT FROM AUTHOR]

In addition to functioning as a carbon sink, mangrove soil also releases greenhouse gases (GHGs) through microbial metabolism. GHG flux fluctuates according to the ecological parameters of mangroves and climate variability. We quantified GHG fluxes from the soil using a closed-chamber technique and assessed soil and porewater conditions in three primary mangrove zones (each zone was dominated by one of the mangrove types) at Ngurah Rai Forest Park, Bali, Indonesia, categorized by genera: Bruguiera, Rhizophora, and Sonneratia. We found that the CO2 flux ranged from 322.5 to 3,494.5 µg/m2/h, CH4 flux ranged from -24.7 to 60.9 µg/m2/h, and N2O flux ranged from -1.2 to 2.3 µg/m2/h. None of the GHG fluxes varied significantly between mangrove zones. Overall, the highest CO2 fluxes were observed in the Bruguiera zones, while the highest CH4 and N2O fluxes were found in the Sonneratia and Rhizophora zones, respectively. A significant relationship between GHG fluxes and soil properties, including soil organic carbon (SOC), total Kjeldahl nitrogen (TKN), water content, bulk density, and soil type. The average warming effect on GHG fluxes ranged from 0.9 and 1.8 MgCO2/ha/year, accounting for only 1.1% to 2.2% of the annual plant carbon sequestration rate of 75.9 to 81.6 MgCO2/ha/year. These findings suggest that the variability of GHG fluxes is not significantly influenced by mangrove type; instead, soil conditions play a crucial role. Calculations of the net carbon stock may overlook the relatively low warming effect of GHG fluxes in this area.

Palm oil (Elaeis guineensis Jacq.) is a crop that can transfer carbon dioxide into carbon storage within the soil. Root pruning also plays a role in enhancing carbon stocks in the plant. This research aims to evaluate the effects of root pruning on oil palm carbon reserves and their association with nutrient absorption. The study was conducted over six months using four-year-old oil palm plants. A nested experimental design with two factors was employed. The first factor, serving as the main plot, involved three root cutting depths (0, 10, and 20 cm), while the second factor consisted of four root cutting intensities (0%, 25%, 50%, and 75%). The findings indicated that root pruning increased the plant's carbon stock, though it remained lower compared to the control. The highest CO2 emission was recorded in the afternoon, specifically in the 20 cm root cutting treatment at 75% intensity, measuring 4.3 μmol·m-2·sec-1. The greatest carbon reserve, 16.98 tons·C·ha-1·year-1, was observed at a 20 cm depth and 75% intensity, with a positive correlation. [ABSTRACT FROM AUTHOR]

Gas separation is a critical application of gas hydrates, and accurately predicting separation performance is crucial. In this study, we used thermodynamic calculations to predict the equilibrium phase of gas hydrates for various mole fractions of CO2 + CH4 gas mixtures. We also determined the mole fraction of each gas component trapped within the hydrate clathrate. To predict the equilibrium points, we used the Soave–Redlich–Kwong（(SRK) equation of state for the gas phase, the nonrandom two-liquid (NRTL)model for the liquid phase, and the Chen–Guo model for the hydrate phase. We modified the hydrate fugacity formula and introduced a new function to improve the accuracy of the Chen–Guo model. By incorporating experimental equilibrium results from our study and another study, we developed a correlation based on gas mixture composition and temperature, resulting in highly accurate predictions. The use of this new correlation for hydrate fugacity calculation significantly improved precision, as evidenced by an average absolute deviation percent of calculated pressures (AADP) of 1.34% for pure CO2 and 1.25% for CH4. When considering the 27 data points of different CO2 + CH4 mixtures, the AADP% was 1.98%.To implement the model to predict equilibrium phases, we used the Chen–Guo framework to determine the mole fraction of each gas component in the hydrate mixture. Interestingly, we discovered a linear correlation between the CO2 mole fraction in the hydrate and equilibrium pressure, with a slope of approximately 0.001 and a y-intercept of less than one, for all gas compositions. Therefore, we can conclude that low thermodynamic conditions (temperature and pressure) result in a high CO2 mole fraction in the hydrate phase and great separation efficiency.

Coal reservoirs are often connected to hydrogeological systems through faults, allowing groundwater with mineralization to intrude into coal seams. In order to improve gas extraction, it is necessary to explore the effect of coal with different moisture content and salinity conditions on CH4 adsorption. By means of various experimental tests, such as XPS, FTIR, we constructed macromolecular structure models of Dongqu 8# coal with different moisture content and salinity conditions, conducted isothermal adsorption simulation experiments, and analyzed in detail the effects of coal models with different moisture content and salinity conditions on the adsorption capacity of CH4. The results showed that the adsorption capacity of CH4 decreased with the increase of moisture content and salinity in coal; the effect of moisture content on CH4 adsorption was greater than that of salinity on CH4 adsorption; the ability of sodium salt to affect the adsorption of CH4 by coal was ranked from largest to smallest as follows: Na2CO3 > NaHCO3> NaCl; electrostatic potential distribution: | Na2CO3 electrostatic potential| > | NaHCO3 of electrostatic potential| > | NaCl of the electrostatic potential|, it can be seen that the electrostatic force affects the strength of adsorption, the greater the value of the electrostatic potential of the ions in the salt, the stronger ability the coal to adsorb CH4.

A COP 28, Conferência das Partes sobre Mudanças Climáticas, destaca-se como um evento crucial para discutir e abordar os desafios relacionados aos gases de efeito estufa (GEE) em um mundo cada vez mais impactado pelas mudanças climáticas. Os GEE, como o dióxido de carbono (CO2), metano (CH4) e óxido nitroso (N2O), são os principais impulsionadores do aquecimento global e representam a preocupação central na COP 28. A necessidade de reduzir as emissões desses gases é incontestável, e estratégias baseadas em dados (data driven) emergem como ferramentas fundamentais para entender e abordar esse desafio complexo. O uso de análises baseadas em dados permite uma compreensão mais precisa das fontes de emissões de GEE, identificando áreas críticas para ação e facilitando a implementação de medidas eficazes de mitigação. Este estudo faz um levantamento dos dados da COP 28, combinando discussões sobre GEE e abordagens data driven os quais desempenham um papel crucial na formulação de políticas e na tomada de decisões direcionadas para enfrentar as mudanças climáticas de forma eficaz e sustentável.

Abstract Background Mangrove ecosystems exhibit significant carbon storage and sequestration. Its capacity to store and sequester significant amounts of carbon makes this ecosystem very important for climate change mitigation. Indonesia, owing to the largest mangrove cover in the world, has approximately 3.14 PgC stored in the mangroves, or about 33% of all carbon stored in coastal ecosystems globally. Unfortunately, our comprehensive understanding of carbon flux is hampered by the incomplete repertoire of field measurement data, especially from mangrove ecosystem-rich regions such as Indonesia and Asia Pacific. This study fills the gap in greenhouse gases (GHGs) flux studies in mangrove ecosystems in Indonesia by quantifying the soil CO2 and CH4 fluxes for different land use types in mangrove ecosystems, i.e., secondary mangrove (SM), restored mangrove (RM), pond embankment (PE) and active aquaculture pond (AP). Environmental parameters such as soil pore salinity, soil pore water pH, soil temperature, air temperature, air humidity and rainfall are also measured. Results GHG fluxes characteristics varied between land use types and ecological conditions. Secondary mangrove and exposed pond embankment are potential GHG flux sources (68.9 ± 7.0 and 58.5 ± 6.2 MgCO2e ha− 1 yr− 1, respectively). Aquaculture pond exhibits the lowest GHG fluxes among other land use types due to constant inundation that serve as a barrier for the release of GHG fluxes to the atmosphere. We found weak relationships between soil CO2 and CH4 fluxes and environmental parameters. Conclusions The data and information on GHG fluxes from different land use types in the mangrove ecosystem will be of importance to accurately assess the potential of the mangrove ecosystem to sequester and emit GHGs. This will support the GHG emission reduction target and strategy that had been set up by the Indonesian Government in its Nationally Determined Contributions (NDC) and Indonesia’s 2030 Forest and Other Land Use (FOLU) Net Sink.

Feeding rate is an important factor influencing the carbon and nitrogen input and greenhouse gas emission from aquaculture systems. However, the quantitative relationship between feeding rates and GHG emissions is still poorly understood. In this study, we conducted a laboratory-scale experiment to examine the impact of feeding rate (0%, 2%, 4%, 6%, and 8%) on the CH4 and N2O emissions from a pond rice-fish co-culture system. The results showed that the total amount of CH4 emission did not significantly differ when the feeding rate was no more than 6%, but increased more than four times when the feeding rate reach to 8%. The amount of N2O emission showed a linearly increasing trend with the feeding rate. The emission factors of CH4 and N2O was significantly higher for 8% feeding rate than other feeding rates. The variation of CH4 emission was primarily attributed to the ratio of mcrA/pmoA in the sediment and the contents of biological oxygen demand (COD) and dissolved oxygen (DO) in the water; and the variation of N2O was primarily affected by the available nitrogen in the water and sediment and the content of DO in the water. The overall emission of CH4 and N2O showed an exponential relationship with feeding rate. The total yields of fish and rice did not continuously increase when the feeding rate exceeded 4%. The lowest emission intensity per unit yield was reached at the feeding rate of 2.99%. These results can provide a reference for the determination of low-carbon feeding strategy for pond rice-fish co-culture system. [ABSTRACT FROM AUTHOR]

Simple Summary: Methanogens are a group of microorganisms with the capability to convert inorganic or organic compounds into methane, impacting the global carbon cycle and greenhouse gas emissions. In anaerobic environments such as wetlands, paddy fields, and reservoirs, methanogens are the primary contributors to methane production. In this study, high-throughput sequencing of the mcrA functional gene was utilized to conduct a comprehensive analysis of the community structure, metabolic pathways, and influencing factors of methanogens in the sediment of 18 reservoirs on the northeastern Qinghai Plateau. The results indicated that the construction of reservoirs has altered the physicochemical properties of river water and sediments, significantly impacting the distribution and succession of methanogenic communities in the sediment. In general, this study can improve our understanding of the biological mechanisms of methane emissions from the reservoirs on the Qinghai Plateau. Reservoirs are a hotspot for methane emissions, a potent greenhouse gas. However, the microbial basis for methane production in the Qinghai Plateau reservoirs remains unclear. To explore the characteristics of methanogenic communities in reservoir sediments on the northeastern Qinghai Plateau, sediment samples were collected from 18 reservoirs in the Yellow River basin during May 2023 (dry season) and August 2023 (wet season). High-throughput sequencing technology was employed to analyze the community composition, diversity, and co-occurrence network of methanogens. Furthermore, FAPROTAX and Mantel analysis were used to assess the metabolic functions of methanogens and their influencing factors. The results showed that (1) the predominant genera of methanogens were Methanobacterium (28.87%) and Methanosarcina (21.67%). Hydrogenotrophic methanogenesis was the main pathway in the sediments. (2) Significant spatiotemporal differences were observed in the diversity of methanogenic communities (p < 0.05). The composition and diversity of these communities were found to be significantly influenced by temperature, pH, altitude, organic carbon, and total nitrogen (p < 0.05). (3) Methanosarcina, Methanobacterium, and Methanospirillum play crucial roles in maintaining the stability of methanogenic community networks. The co-occurrence network nodes are predominantly positively correlated (99.82%). These results provide data for further studies on carbon cycling in the Qinghai Plateau reservoirs. [ABSTRACT FROM AUTHOR]

Reference gas adsorption isotherms are useful for validating equilibrium data obtained from various techniques and for ensuring that experimental systems are operating correctly. In this work, we extend an interlaboratory study on a NIST reference zeolite (Na-Y, RM8850) to two additional temperatures above and below the original 298.15 K, validating the results via independent measurements using two different techniques. Volumetric experiments on a novel Adsorption Differential Volumetric Apparatus (ADVA-270) were carried out at The University of Edinburgh, and gravimetric experiments were performed at Hiden Isochema using a proprietary XEMIS microbalance. Both techniques provided highly accurate results and an excellent match between the two independent measurements using less than 150 mg of sample. Absolute equilibrium data were modelled using a Langmuir-virial isotherm to obtain an accurate concentration dependence of the heat of adsorption. [ABSTRACT FROM AUTHOR]

A thermal dynamic disaster in the goaf is one of the most serious coal mine disasters formed by coal spontaneous combustion and gas interweaving. However, the influence of the high-temperature hidden fire source formed in the goaf on the evolution law of thermal dynamic disasters is not clear, and effective prevention and control measures cannot be taken. Therefore, this paper uses the experimental platform of thermal dynamic disaster in the goaf to study the influence of different fire point positions on the development of thermal dynamic disaster in the goaf through a similar simulation experiment of thermal dynamic disaster evolution in the goaf and analyzes the corresponding relationship between temperature and CO concentration in the upper corner. The results show that under different locations of heat source, the high-temperature heat source of coal spontaneous combustion migrates to the air leakage side with sufficient oxygen supply, and an oxygen-poor circle is formed near the ignition point. Under the action of air leakage flow, CH4 accumulates in the deep part of the goaf on the return air side. Due to the increase in coal, part of CH4 is produced, which leads to the increase in concentration of CH4 at the ignition point. Under the action of different heat sources, the changing trend of concentration of CO and temperature in the return air corner is the same, but the temperature change in the return air corner shows a lag compared with the change in the concentration of CO, so concentration monitoring of CO can reflect the evolution process of the fire field in the goaf more quickly than temperature monitoring. [ABSTRACT FROM AUTHOR]

The photocatalytic partial oxidation of CH4 to CH3OH, HCHO and other products is a potential low-energy CH4 conversion path, which has the problems of high activation difficulty of CH4 and low product selectivity. The design and preparation of high-performance catalysts are crucial to solve these problems. Based on the hydrothermal method, ZnO-x catalysts with different morphologies including granules, nano-flower, nano-flake and agglomerated nanoparticles were prepared by varying Zn precursors. It is found that the morphologies of ZnO-x has a significant effect on photocatalytic partial oxidation of CH4 to HCHO (short for "CH4 photocatalytic oxidation performance"). The nAgCl/ZnO-Cl photocatalysts (n is the mole fraction of AgNO3) were further prepared by using ZnO-Cl as the substrate with the best CH4 photocatalytic oxidation performance. The samples were characterized by X-ray diffraction, N2 adsorption/desorption and scanning electron microscopy, etc. The results show that 2.0%AgCl/Zn0-Cl shows the best CH4 photocatalytic oxidation performance. Under the action of 5 mg 2.0%AgCl/Zn0-Cl and reaction conditions of temperature of 25 °C, O2 pressure of 0.1 MPa, CH4 pressure of 2.9 MPa, H2O volume of 75 mL, light intensity of 450 mW/cm² and illumination time of 2 h. The total yield of oxygenated liquid products (CH3OH + CH3OOH + HCHO) is 10409 µmol/(g⋅h), and the total selectivity of oxygenated liquid products is 91.4%, and the main product HCHO is 6271 µmol/(g⋅h) with HCHO selectivity of 60.2%. Based on radical trapping experiments, it is found that the formation of •O2- and the holes are the key to the activation of CH4 to •CH3, and more importantly, interaction of •O2- and •CH3 becomes the major reaction path. In such a way, the initial product (CH3OOH) can be further oxidized to HCHO, and thus leading to the promotion of HCHO selectivity of nAgCl/ZnO-Cl. [ABSTRACT FROM AUTHOR]

South Africa faces the urgency to comprehensively understand and manage its methane (CH4) emissions. The primary aim of this study is to compare CH4 concentrations between Eastern Cape and Mpumalanga regions dominated by cattle farming and coal mining industries, respectively. CH4 concentration trends were analyzed for the period 2019 to 2023 using satellite data. Trend analysis revealed significant increasing trends in CH4 concentrations in both provinces, supported by Mann–Kendall tests that rejected the null hypothesis of no trend (Eastern Cape: p-value = 8.9018e−08 and Mpumalanga: p-value = 2.4650e−10). The Eastern Cape, a leading cattle farming province, exhibited cyclical patterns and increasing CH4 concentrations, while Mpumalanga, a major coal mining province, displayed similar increasing trends with sharper concentration points. The results show seasonal variations in CH4 concentrations in the Eastern Cape and Mpumalanga provinces. High CH4 concentrations are observed in the northwestern region during the December-January–February (DJF) season, while lower concentrations are observed in the March–April-May (MAM) and June-July–August (JJA) seasons in the Eastern Cape province. In the Mpumalanga province, there is a dominance of high CH4 concentrations in southwestern regions and moderately low concentrations in the northeastern regions, observed consistently across all seasons. The study also showed an increasing CH4 concentration trend from 2019 to 2023 for both provinces. The study highlights the urgent need to address CH4 emissions from both cattle farming and coal mining activities to mitigate environmental impacts and promote sustainable development. Utilizing geographic information system (GIS) and remote sensing technologies, policymakers and stakeholders can identify and address the sources of CH4 emissions more effectively, thereby contributing to environmental conservation and sustainable resource management. [ABSTRACT FROM AUTHOR]

The CH4 storage by adsorption on activated carbons for natural gas handling has gained interest due to the appearance of lightweight materials with large surface areas and pore volumes. Consequently, kinetic parameters estimation of the adsorptive process can play a crucial role in understanding and scaling up the system. Concerning its versatility, banana peel (BP) is a biomass with potential for obtaining different products, such as biochar, a solid residue from the biomass' thermal decomposition of difficult disposal, where through an activation process, the material porous features are taken advantage to application as adsorbent of gaseous substances. This research reported data for the CH4 adsorption kinetic modeling by biochar from BP pyrolysis. The activated biochar textural characterization showed particles with fine mesoporous structure (pore diameter ranging between 29.39 and 55.62 Å). Adsorption kinetic analysis indicated that a modified pseudo-first-order model was the most suitable to represent the experimental data, with equilibrium adsorption of 28 mg g−1 for the samples activated with 20.0% vol wt.−1 of H3PO4 and pyrolysis at 500 °C. The equilibrium constant was consistent with the Freundlich isotherm model, suggesting a physisorption mechanism, and led to a non-ideal, reversible, and not limited to monolayer CH4 adsorption. [ABSTRACT FROM AUTHOR]

Invasive Spartina alterniflora (S. alterniflora) has significant impacts on sediment biogeochemical cycling in the tidal wetlands of estuaries and coasts. However, the impact of exotic Spartina alterniflora invasion on greenhouse gases (GHGs) production dynamics in sediments remain limited. Here, we investigated the dynamics of sediment physicochemical properties, GHGs production rates, and microbial gene abundances in a native Cyperus malacensis habitat and three invasive S. alterniflora habitats (6-, 10-, and 14-year) in the Minjiang River Estuary, China. The methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O) production rates varied both spatially and seasonally, while microbial gene abundances (bacterial and fungal gene abundances) and organic matter (TOC and TN) only varied spatially. GHGs production rates were also characterized by higher values in surface sediment (0-10 cm) compared to subsurface sediment (10-20 cm) and by seasonal variations with higher values in summer than in winter. S. alterniflora invasion can significantly increase CH4 and CO2 production rates, organic matter, and microbial gene abundances (p < 0.05). Temperature, organic matter and microbial gene abundances were the most dominating factor controlling the spatio-temporal variations of CH4 and CO2 production rates. Overall, our findings highlighted the significant role of S. alterniflora invasion in regulating GHGs production rates in coastal wetland sediments and provided fundamental data for estimating GHGs emissions and carbon sequestration in the complex tidal wetlands. [ABSTRACT FROM AUTHOR]

Combustible gases produced during the coal spontaneous combustion (CSC) process will cause hidden danger for mine safety. For studying the effect of the addition of CSC gas on CH4 explosion characteristics, a 20 L explosive device was adopted to obtain the explosion characteristics of CH4 (7%, 9.5%, and 11% in vol.) and CSC gas (0-2% in vol.) premixed fuel, and the effect of CSC gas on CH4 explosion characteristics was analyzed. Results show that for 7% CH4, CSC gas promotes the CH4 explosion. However, for 11% CH4, CSC gas inhibits the explosion of CH4. Based on the chemical reaction kinetics analysis, it indicates that adding CSC gas at different stages changes the sensitivity coefficients, which affects the concentration of active radicals. With the increase of CSC gas in CH4, the concentration of H increased, the concentration of O decreased, and the concentration of OH increased first and then decreased. The variations of O and OH are regarded to be the main reason for promoting the explosion of dilute CH4 and inhibiting the explosion of concentrated CH4. The variations of H, O, and OH indicate that the addition of the self-heating oxidation stage of CSC gas has a more evident effect on the CH4 explosion characteristics. [ABSTRACT FROM AUTHOR]

Atmospheric methane is one of the major greenhouse gases with a drastic impact on climate change. This study developed a random forest model to obtain a daily 5 km resolution atmospheric methane concentration dataset with full spatial coverage (100%) from 2019 to 2021 in mainland China, thereby filling the gap in the methane product data from the Tropospheric Monitoring Instrument (TROPOMI). The coefficients of determination for a sample-based and spatial-based cross-validation are 0.97 and 0.93, respectively. The average deviation of the seamless methane product reconstructed by the random forest model is less than 1%, validated with the measured methane concentration data from the Total Carbon Column Observing Network sites. Methane concentrations in China show a distribution of high in the east and south and low in the west and north. The high-concentration areas include Central China, the Sichuan Basin, the Pearl River Delta, and the Yangtze River Delta. In terms of time scale, the methane concentration has evident seasonal variation, as it is low in spring (average 1852 ppb) and winter (average 1881 ppb) and high in summer (average 1885 ppb) and autumn (average 1886 ppb). This is mainly due to the significant increase in emissions from rice cultivation and wetlands during the summer and autumn. During the COVID-19 pandemic, the methane concentration decreases significantly and then starts to return to normal around 70 days after the Lunar New Year, indicating that the seamless methane product can potentially detect anomalous changes in methane concentration. [ABSTRACT FROM AUTHOR]

To investigate the influence of Ag and the loading of Ni species, Ni-Ag type catalysts were synthesized with varying Ni/Ag ratios (1, 1.5 and 2) using the coprecipitation method. The catalysts were extensively characterized using various techniques such as TG-DSC-SM, XRD, ICP, BET, SEM-EDX and TPR and subsequently tested in the CH4/CO2 reaction without any pretreatment. Regardless of the ratio employed, a phase mixture containing NiO and Ag was observed after calcination under air between 600 °C and 1200 °C. SEM analysis confirmed the presence of a close interface between Ag and NiO. The specific surface area was found to be significantly higher for the catalyst with lower Ni content (R = 1). TPR analysis demonstrated that the inclusion of Ag facilitated the reduction of Ni at lower temperatures. XRD analyses of the spent catalyst confirmed catalyst reduction during the reaction. Among the samples, a catalyst with Ni/Ag = 1 exhibited superior catalytic activity without any pretreatment under a reduction atmosphere, in which case the conversions of methane and CO2 at 650 °C amounted to 38 and 45 mol%, respectively, with H2/CO = 0.7 and 71 mol% of H2. The presence of Ag species enhances the stability of the Ni catalyst and improves catalytic performance in the dry reforming of methane. [ABSTRACT FROM AUTHOR]

Soil is an important source and sink of greenhouse gas carbon dioxide (CO2) and methane (CH4). During CH4 consumption CO2 is produced as an end product. It is generally assumed that CO2 would inhibit CH4 consumption due to feedback inhibition. To test the effect of CO2 on methanotrophy, experiments were conducted in microcosms with different initial concentration of CO2 and CH4. Changes in CH4 consumption potential and abundance of pmoA gene copies in relation to CO2 concentration were estimated. In general, CH4 consumption ceased in the absence of CO2. In presence of CO2, rate of CH4 consumption (ng CH4 consumed g−1 soil d−1) varied from 0.283 to 0.481 at 1000 ppm of CH4 and 2.958 to 4.994 at 10,000 ppm of CH4. Abundance of methanotrophs (pmoA gene copies g−1 soil) ranged from 4.5 × 105 to 107 × 105 g−1 soil. A follow up experiment was carried out to evaluate CH4 consumption in the presence or absence of CO2, which proved that CO2 is essential for CH4 consumption. Study concludes that CO2 is a precursor molecule for CH4 consumption in soil ecosystem and methanotrophs are capable of mitigating both the greenhouse gases, CH4 and CO2. [ABSTRACT FROM AUTHOR]

The abilities of Ni-Si52, Ni-SiNT(6, 0), Ni-C52, Ni-B26N26, Ni-CNT (6, 0) and Ni-BNNT (6, 0) as catalyst of CO2-RR to CH4 are compared. The Eadoption and Eformation of Ni-Si52, Ni-SiNT(6, 0), Ni-C52, Ni-B26N26, Ni-CNT (6, 0) and Ni-BNNT (6, 0) are stable parameters. The Eadoption of CO2-RR on Ni-Si52, Ni-SiNT(6, 0), Ni-C52, Ni-B26N26, Ni-CNT (6, 0) and Ni-BNNT (6, 0) are − 3.34, -3.47, -5.42, -3.81, -3.99 and − 5.89 eV. The HCOOH, CO, HCOH, CH3OH and CH4 adsorption as important products for CO2-RR on Ni doped nanotubes an nanocages are examined. The Eformation of CO2-RR on Ni-Si52, Ni-SiNT(6, 0), Ni-C52, Ni-B26N26, Ni-CNT (6, 0) and Ni-BNNT (6, 0) are − 4.27, -4.39, -4.51, -4.87, -5.02 and − 4.92 eV. The CO2-RR mechanisms on Ni doped nanotubes and nanocages are examined. The overpotential of CO2-RR on Ni-Si52, Ni-SiNT(6, 0), Ni-C52, Ni-B26N26, Ni-CNT (6, 0) and Ni-BNNT (6, 0) are 0.338, 0.327, 0.331, 0.304, 0.295 and 0.296 V. The Overpotential of CO2-RR on Ni-C52, Ni-B26N26, Ni-CNT (6, 0) and Ni-BNNT (6, 0) are lower than metal catalysts. The Ni-Si52, Ni-SiNT(6, 0), Ni-C52, Ni-B26N26, Ni-CNT (6, 0) and Ni-BNNT (6, 0) is processed the CO2-RR. [ABSTRACT FROM AUTHOR]

Background: Mangrove ecosystems exhibit significant carbon storage and sequestration. Its capacity to store and sequester significant amounts of carbon makes this ecosystem very important for climate change mitigation. Indonesia, owing to the largest mangrove cover in the world, has approximately 3.14 PgC stored in the mangroves, or about 33% of all carbon stored in coastal ecosystems globally. Unfortunately, our comprehensive understanding of carbon flux is hampered by the incomplete repertoire of field measurement data, especially from mangrove ecosystem-rich regions such as Indonesia and Asia Pacific. This study fills the gap in greenhouse gases (GHGs) flux studies in mangrove ecosystems in Indonesia by quantifying the soil CO2 and CH4 fluxes for different land use types in mangrove ecosystems, i.e., secondary mangrove (SM), restored mangrove (RM), pond embankment (PE) and active aquaculture pond (AP). Environmental parameters such as soil pore salinity, soil pore water pH, soil temperature, air temperature, air humidity and rainfall are also measured. Results: GHG fluxes characteristics varied between land use types and ecological conditions. Secondary mangrove and exposed pond embankment are potential GHG flux sources (68.9 ± 7.0 and 58.5 ± 6.2 MgCO2e ha− 1 yr− 1, respectively). Aquaculture pond exhibits the lowest GHG fluxes among other land use types due to constant inundation that serve as a barrier for the release of GHG fluxes to the atmosphere. We found weak relationships between soil CO2 and CH4 fluxes and environmental parameters. Conclusions: The data and information on GHG fluxes from different land use types in the mangrove ecosystem will be of importance to accurately assess the potential of the mangrove ecosystem to sequester and emit GHGs. This will support the GHG emission reduction target and strategy that had been set up by the Indonesian Government in its Nationally Determined Contributions (NDC) and Indonesia's 2030 Forest and Other Land Use (FOLU) Net Sink. [ABSTRACT FROM AUTHOR]

The objective of this study is to establish controlled-release nitrogen fertilization technology for achieving high yield and reduce carbon emissions. Two late-maturing medium japonica rice varieties, Nanjing 9108 and Taixiangjing 1402, were selected in this study. The controlled-release fertilizer with resin-coated urea (N 43%, the longevity was 100 d) and common urea (46% N) were used as nitrogen fertilizers. Different ratios of basal and panicle nitrogen fertilizers were set for different treatments of 10 : 0 (NM1), 8 : 2 (NM2), 7 : 3 (NM3), and 6 : 4 (NM4). The basal fertilizer was applied using the side-deep fertilization method, with a ratio of 5:5 for resin-coated urea and common urea. The panicle nitrogen fertilizer was common urea. Conventional fertilization (FFT) and no nitrogen fertilizer (0N) control treatments were also included. The effect of different nitrogen fertilizer application methods on rice yield, NH3 volatilization, and greenhouse gas emissions were investigated. The results showed that the side-deep application of controlled-release nitrogen fertilizer delayed the peak of NH3 volatilization, preventing it from occurring at tillering stage compared to the FFT treatment. In addition, the flux of NH3 volatilization and the average flux after topdressing were significantly reduced by the side-deep application of controlled-release nitrogen fertilizer. The NH3 emission accumulation, NH3 emission factor, and NH3 emission intensity were reduced by 25.33%-48.76%, 29.14%-60.81%, and 29.60%-56.01%, respectively. Furthermore, the CH4 emission fluxes were significantly reduced at tillering stage and after heading stage. The N2O emission fluxes were also significantly reduced during the shelving and heading period. The CH4 and N2O emission accumulation were reduced by 20.20%-55.04% and 25.56%-61.56%, respectively. The CH4 emission reduction rate decreased as the proportion of basal and panicle fertilizer decreased. The N2O emission reduction rate followed the order of NM1 > NM3 > NM2 > NM4. The GWP and GHGI were reduced by 20.96%-53.35% and 25.91%-55.40%, respectively. Considering the economic and ecological benefits, NM1 treatment had the best effect on the reduction of NH3 volatilization and greenhouse gas emissions. NM1 treatment reduced the number of fertilization times 1-2 compared with the NM3 and FFT treatments, which was advantageous for achieving green, simple, and large-scale rice production. NM3 treatment exhibited the highest increase in yield, and its impact on reducing NH3 volatilization and greenhouse gas emissions was second only to NM1 treatment. In summary, the present study explored a set of controlled-release nitrogen fertilization method (NM1 and NM3 focused on "light and simple + emission reduction" and "high yield + emission reduction", respectively) suitable for reducing emission and increasing yield of late-maturing medium japonica rice. [ABSTRACT FROM AUTHOR]

Since the industrial revolution, enhancement of atmospheric greenhouse gas concentrations as a result of human activities has been the primary cause of global warming. The monitoring and evaluation of greenhouse gases are significant prerequisites for carbon emission control. Using monthly data of global atmospheric carbon dioxide (CO2) and methane (CH4) column concentrations (hereinafter XCO2 and XCH4, respectively) retrieved by the Greenhouse Gas Observation Satellite (GOSAT), we analyzed the variations in XCO2 and XCH4 in China during 2010–2022 after confirming the reliability of the data. Then, the influence of a strong El Niño event in 2015–2016 on XCO2 and XCH4 variations in China was further studied. The results show that the retrieved XCO2 and XCH4 from GOSAT have similar temporal variation trends and significant correlations with the ground observation and emission inventory data of an atmospheric background station, which could be used to assess the variations in XCO2 and XCH4 in China. XCO2 is high in spring and winter while XCH4 is high in autumn. Both XCO2 and XCH4 gradually declined from Southeast China to Northwest and Northeast China, with variation ranges of 401–406 and 1.81–1.88 ppmv, respectively; and the high value areas are located in the middle–lower Yangtze River basin. XCO2 and XCH4 in China increased as a whole during 2010–2022, with rapid enhancement and high levels of XCO2 and XCH4 in several areas. The significant increases in XCO2 and XCH4 over China in 2016 might be closely related to the strong El Niño–Southern Oscillation (ENSO) event during 2015–2016. Under a global warming background in 2015, XCO2 and XCH4 increased by 0.768% and 0.657% in 2016 in China. Data analysis reveals that both the XCO2 and XCH4 variations might reflect the significant impact of the ENSO event on glacier melting in the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

The catalytic activity of Vanadium, Scandium, Titanium and Ferrum (Sc, V, Ti and Fe) doped Carbon, Silicon, Germanium, Aluminum Nitride and Boron Phosphide (C60, Si46, Al30N30, Ge72 and B41P41) nanocages for reduction reaction of carbon dioxide are investigated. The ∆Ebinding of V2-C58, Sc2-Si44, V2-Al29N29, Ti2-Ge70 and Fe2-B40P40 nanocages are -5.90, -6.23, -6.13, -7.28 and -6.97 eV, respectively. The ∆Eformation of V2-C58, Sc2-Si44, V2-Al29N29, Ti2-Ge70 and Fe2-B40P40 nanocages are -4.54, -4.84, -4.76, -5.66 and -5.42 eV, respectively. The ∆Ebinding and ∆Eformation of double metal atoms doped nanocages are demonstrated that they are stable nano-structures. The rate-determining step for CH4 and CH3OH production is the catalyst-*CO → catalyst-*CHO on double metal atoms doped nanocages. The overpotential of CH3OH and CH4 production on Ti2-Ge70, Fe2-B40P40, V2-C58, V2-Al29N29 and Sc2-Si44 nanocages are 0.19 to 0.26 V and 0.18 to 0.24 V, respectively. The Sc2-Si44, V2-Al29N29, Ti2-Ge70 and Fe2-B40P40 can catalyze the CO2-RR with high efficiency. The double metal atoms doped nanocages (Ti2-Ge70, Fe2-B40P40, V2-C58, V2-Al29N29 and Sc2-Si44) can be considered as electro-catalysts for CH4 and CO3OH creation from CO2 reduction reaction. [ABSTRACT FROM AUTHOR]

The use of oilseed rape (OS, Brassica napus L.) as a winter green manure is crucial for enhancing soil fertility and reducing chemical N application in paddy fields. However, the impacts of replacing varying amounts of chemical N with OS on CH4 and N2O emissions in paddy soils have not been well evaluated. In this study, GHG emissions, soil properties and OS decomposition in a rice-ratooning system with different OS-urea N replacement rates (0%, 25%, 50%, 75% and 100%) were investigated. Our results indicate that 84.7–90.7% of the initial C and 97.5–98.4% of the N were released during the 192-day decomposition process, and that the mineralization patterns of net C and net N in the OS residue were consistent with a single exponential decay model. The lowest CH4 emissions (9.97 g m−2) were observed at 0% OS, while the highest N2O emissions (0.40 g m−2) were observed at this level of substitution. Conversely, the highest CH4 emissions (20.71 g m−2) and lowest N2O emissions (0.07 g m−2) were observed at 100% OS. Compared to 0% substitution, 25% substitution significantly decreased GWP and GHGI without reducing rice grain yield. Environmental parameters such as soil redox, NH4+-N and residual N and C were shown to be significantly associated with CH4 emissions, whereas soil redox, NH4+-N and residual C were the main drivers of N2O emissions. In conclusion, 25% substitution of OS was the most cost-effective measure for balancing greenhouse gas emission and rice yield. [ABSTRACT FROM AUTHOR]

Carbon nanofibers (CNFs) modified with CeO2 were employed as support for the synthesis of Ni catalysts for the CO2 methanation reaction. Two different preparation methods were investigated: incipient wetness impregnation and mechanochemical synthesis. The catalysts were tested at atmospheric pressure under a wide range of temperatures (200 – 600 °C) using a stoichiometric ratio of undiluted H2/CO2 and a flow to weight ratio of 600 NL h−1 gNi−1. The results showed that the Ni-CeO2/CNF catalyst prepared by mechanochemical synthesis showed higher CO2 conversion and CH4 selectivity at low temperatures than the one prepared via traditional method. This was attributed to smaller Ni crystallites and to the higher quantity of Ce3+ sites exposed by the milling process. Stress test carried out at 450 °C showed that the activity and the reaction mechanism remained stable for at least 50 h.

Eco-enzyme solutions are generally used in the manufacture of disinfectants, floor cleaners, liquid fertilizers, preservatives and others. In this study, eco-enzyme was used as the main ingredient in the manufacture of biogas fermentation with the addition of cow feces as an additional starter in the fermentation. The aim of this study was to determine the content of CH4, CO2, N2, pH, temperature, and pressure in eco-enzyme fermentation with the addition of cow feces starter. his research is a quantitative research with the type of experimental research as well as direct observation data collection techniques and data analysis techniques using descriptive statistical analysis. The results showed that the treatment that produced the highest methane (CH4) gas was the P5 treatment with a concentration of 2.889%. 6,1. The highest volume pressure value was produced in the P5 treatment which was 70 ml. Nitrogen gas (N2) and carbon dioxide gas (CO2), the concentration of nitrogen gas (N2) from reactor P0 - P4 is in the range of 95.875-99.669 % and the concentration of carbon dioxide (CO2) from reactor P0 - P4 is in the range of 0.237 - 4.125 %.

Methane (CH4) clumped isotope analysis plays a crucial role in the fields of climate change, energy exploration, and planetary research. The purity of CH4 in samples directly affects the precision and accuracy of high-resolution mass spectrometry in clumped isotope analysis. Addressing the challenge associated with enriching and purifying CH4 components in gas samples, this study optimized conditions such as carrier gas line speed and sample injection volume based on the principles of gas chromatography (GC) component separation, with real-time monitoring of component peak shapes. Additionally, the recovery rate was quantified using an external standard method and purity was verified through GC component analysis to ensure the effectiveness of the purification process. By optimizing the chromatography-vacuum low-temperature enrichment preparation method, the optimal carrier gas line speed for the IBEX system was determined to be 12 mL/min, with a CH4 injection volume less than 12 mL. This facilitated visualization of GC peak shapes, thus ensured that the CH4 peak was essentially separated from the adjacent N2 interference peak, achieving high-purity enrichment of the CH4 single component. When the CH4 content in gas samples was less than 70% and the air content was high, secondary purification was required to improve CH4 purity. The causes of CH4 isotopic fractionation during purification using adsorbents like 5Å molecular sieves were discussed, and extending the CH4 collection time was proposed to eliminate the interference from the 5Å molecular sieve. Currently, this method requires approximately 90 min for a single purification process, with CH4 recovery and purity ranging from 90.1% to 95.7% and 97.3% to 98.9%, respectively. The differences in isotopic composition (δ13CVPDB and δDVSMOW, Δ13CH3D, and Δ12CH2D2) are all less than the analytical error of the mass spectrometer, making them almost negligible.

Biaxial rotary tillage in dryland (DBRT) can complete biaxial rotary tillage with straw incorporation, secondary suppression, and ditching, and it has been previously studied in direct-seeded rice and wheat. However, the effects of DBRT on the mechanically transplanted rice yield and greenhouse gas emissions remain unclear. To evaluate the effects of DBRT on improving the food security of mechanically transplanted rice and reducing the greenhouse gas emissions, we conducted an experiment for two years with wheat straw incorporation. Three tillage methods were set up: DBRT, uniaxial rotary tillage in dryland and paddy (DPURT), and uniaxial rotary tillage in paddy (PURT). The results showed that compared with DPURT and PURT, DBRT increased the yield of machine-transplanted rice by 7.5–11.0% and 13.3–26.7%, respectively, while the seasonal cumulative CH4 emissions were reduced by 13.9–21.2% and 30.2–37.0%, respectively, and the seasonal cumulative N2O emissions were increased by 13.5–28.6% and 50.0–73.1%, respectively. Consequently, DBRT reduced the global warming potential by 10.7–15.5% and 23.7–28.6%, respectively, and the yield-scaled global warming potential by 18.2–21.8% and 36.4–39.3%, respectively, compared to DPURT and PURT. These results were mainly related to the fact that DBRT significantly reduced soil bulk density and increased soil redox potential (Eh). Therefore, implementing DBRT in machine-transplanted rice fields is feasible, which cannot only increase the rice yield, but also reduce the greenhouse gas emissions.