Search Results (54)

N₂O (Nitrous oxide) is a potent greenhouse gas with a global warming potential nearly 300 times that of CO₂ and poses a critical environmental challenge, particularly in semiconductor and display manufacturing, where it is emitted during plasma processes. However, catalytic N₂O abatement in O₂-rich environments remains inefficient because O₂ competitively occupies active sites and hinders the turnover of surface oxygen species. To clarify how support properties govern this inhibition, Co-based catalysts supported on beta zeolite, CeO₂, and TiO₂, together with unsupported Co₃O₄, were comparatively evaluated for direct N₂O decomposition. Among them, Co/Beta exhibited the highest performance, achieving >95% N₂O conversion at 450 °C in the presence of 5% O₂ with excellent long-term stability. Co/Beta possessed a high specific surface area (649 m² g⁻¹) and a mesoporous framework that favored uniform Co dispersion and reactant accessibility, while its high Co²⁺/(Co²⁺ + Co³⁺) ratio (75.5%) and large fraction of chemisorbed oxygen species (79.9%) promoted oxygen-vacancy formation and facile oxygen exchange. These results indicate that the ability of Co/Beta to maintain high activity in the presence of oxygen stems from support-modulated cobalt surface states and enhanced oxygen turnover behavior. These findings provide a support-design principle for stable N₂O decomposition under oxygen-containing exhaust conditions. Full article

In permanently submerged coastal wetlands, interactions between biogeochemical processes and microbial communities strongly influence greenhouse gas (GHG) fluxes. To improve our understanding of how redox-driven processes shape GHG dynamics in these ecosystems, we investigated the relationships among iron (Fe) pools, microbial dynamics, and the potential GHG production in subaqueous soils from an interdunal wetland in San Vitale Park (Italy), permanently submerged and affected by seasonal oscillations of the saline water table. Two subaqueous soil columns (WAS-2 and WAS-4), collected from similar settings, were analyzed. Surface layers of WAS-4 showed higher salinity and carbonate content, whereas WAS-2 was characterized by overall higher Fe concentrations. Distinct vertical distributions of organic matter and sulfur (S) were shown along depth. Laboratory incubations revealed that nitrous oxide (N₂O) production was up to ten times higher in WAS-2 than in WAS-4, with peaks in the top 13–14 cm, consistent with more active nitrification-denitrification in surface layers. Methane (CH₄) and carbon dioxide (CO₂) fluxes decreased with depth, reflecting reduced availability of labile carbon. Methanomicrobiales dominated CH₄-producing layers, indicating hydrogenotrophic methanogenesis, while amoA-carrying Nitrosomonadales and Thaumarchaeota, occurred in shallow, organic-rich layers where ammonia supported nitrification and denitrification. Denitrifiers mainly belonged to α- and β-Proteobacteria, consistent with their direct contribution to N₂O peaks. Spearman’s correlations showed N₂O positively correlated to sulfur and labile carbon (C), supporting denitrification under moderately reducing conditions. CH₄ and CO₂ positively correlated with organic C (Corg), total nitrogen (TN), and reactive Fe forms, reflecting redox-mediated microbial respiration and methanogenesis. Trace elements (B, Cr, Cu, Ni) acted as micronutrients or inhibitors depending on concentration. Canonical correspondence analysis indicated depth-structured links among gas fluxes, soil chemistry (Corg, TN, S/C, CaCO₃, P), and microbial distributions: surface layers, rich in labile C and nutrients, supported active bacteria and archaea involved in decomposition, nitrification, and denitrification, whereas deeper layers hosted oligotrophic archaea adapted to inorganic substrates. Overall, Fe pools appeared to be associated with soil processes relevant to GHG dynamics, although the extent of their regulatory role remains uncertain due to potential alterations of redox-sensitive Fe fractions during sample handling. These results contribute to broader efforts to predict GHG emissions in submerged wetland soils by linking redox stratification, inorganic chemistry, and microbial functional groups. Full article

Nitrous oxide (N₂O) emissions in cereal-based rotations often show short-lived peaks after fertilization, but their contribution to annual budgets and their responsiveness to straw management remain poorly quantified. We combined a 13-year legacy fertilization experiment with two years of high-frequency N₂O monitoring in a rice–wheat rotation in central China to quantify post-fertilization peak windows and test how straw-return rate modulates these windows and annual emissions. Five long-term treatments were compared: an unfertilized control (CK), straw only (2M, 12 t ha⁻¹ yr⁻¹), mineral fertilizer (NPK), and NPK with 6 or 12 t ha⁻¹ yr⁻¹ straw (MNPK and 2MNPK). Under N input, wheat-season emissions dominated annual totals, with the ratio of wheat-season to annual N₂O emissions (WN/TN, where WN denotes wheat-season N₂O emissions and TN denotes annual cumulative N₂O emissions) of ~73–75% for NPK and MNPK, significantly higher than in CK and the straw-only control. Decomposition of annual fluxes showed that 56.6–65.4% of N₂O in N-applied treatments occurred within short windows after the two wheat-season fertilizations, whereas rice-season peaks were small and largely insensitive to treatment. Planned contrasts expressed as geometric mean ratios (GMRs) with 95% confidence intervals (CIs) highlighted a strong management leverage point: increasing straw from 6 to 12 t ha⁻¹ yr⁻¹ with NPK reduced annual and wheat-season N₂O by ~47% and 58%, respectively, primarily by lowering peak magnitude and shortening peak duration. Microbial analyses suggested that treatment effects on N₂O were better reflected by community compositional shifts (β-diversity) than by α-diversity, while amoA abundance showed guild-specific responses. Collectively, this study provides an event-window quantification framework that links high-frequency field measurements to a specific, actionable mitigation lever (straw-return rate) in rice–wheat systems. Together, these results identify wheat-season post-fertilization windows as the main control points for annual N₂O in rice–wheat rotations and show that pairing NPK fertilization with higher straw return can temper short-lived peaks. By explicitly pinpointing when (which windows) and how (attenuating peak magnitude and duration) mitigation is achieved, our findings offer a management-ready and transferable basis for targeted N₂O abatement in double-cropping systems. Full article

Forest fine root litter enters agricultural soils in some cases and its decomposition would change the soil’s properties. However, how this process further influences the ammonia (NH₃) volatilization and nitrous oxide (N₂O) emission from agricultural soil receiving fertilizer nitrogen (N) is unknown. Here, we conducted a soil pot experiment to investigate the responses of the aforementioned gaseous N losses during wheat season to fine root litters derived from Populus deltoides (RP) and Metasequoia glyptostroboides (RM) incorporations. The results showed that two forest fine root litters reduced total NH₃ losses by 30.6−31.9% from 180 kg N ha⁻¹ applied to farmland soil, and this effect was attributed to decreased soil urease activity and ammonium-N during the basal N fertilization period. Whether receiving fertilizer N or not, N₂O emissions from farmland soil were significantly (p < 0.05) mitigated by 62.8–68.2% and 43.0−50.0% following the RP and RM incorporation, respectively. Lower N₂O emission was ascribed to increased soil pH but decreased soil nitrate-N and bulk density. In addition, less AOA and AOB amoA but more nosZ gene abundances explained the fine root litter-induced N₂O mitigation effect. Neither forest fine root litter exerted a negative effect on wheat grain yield and crop N use efficiency in N-added agriculture soil. In conclusion, forest fine root litter incorporation could help to mitigate gaseous N losses via NH₃ volatilization and N₂O emission from fertilizer-N-applied agricultural soils, and without crop production loss. Full article

Composting is a useful way to reduce and recycle agricultural and forestry waste; however, low-temperature environments can inhibit the microbial processes involved in composting. Spent mushroom substrate has a high lignocellulose content, making it particularly difficult to decompose. There is a need to explore methods for effectively promoting microbial activity and enhancing composting efficiency under low-temperature conditions. This study explored the use of C/N ratio adjustments and a microbial inoculum (PLC-8; comprising Proteobacteria, Bacteroidetes, Actinobacteria, Firmicutes, Basidiomycota, Ascomycota, and Cryptomonadales) to improve spent mushroom substrate composting in a low-temperature environment. The temperature, lignocellulose content, pH, and gas emissions were measured during composting, and the microbial community structure was determined to explore associations between biotic and abiotic factors. Compost piles with PLC-8 entered the high-temperature period in 25 days, which was 15 days earlier than the control pile. When the C/N ratio was adjusted to 30:1 and PLC-8 was applied, the cellulose and hemicellulose degradation rates after 60 days were 88.04% and 71.95%, whereas the control group only exhibited degradation rates of 25.39% and 35.64%. Moreover, PLC-8 significantly increased CH₄ and CO₂ emissions and reduced nitrous oxide emissions. Microbial community analysis showed that Proteobacteria and Ascomycota were the dominant phyla in the piles with PLC-8, and these phyla were responsible for lignocellulose decomposition and carbon metabolism. Full article

Livestock and poultry manure emits substantial amounts of ammonia and non-CO₂ greenhouse gases of nitrous oxide and methane, contributing simultaneously to climate forcing and air quality degradation. However, few studies have provided an integrated quantification of ammonia, nitrous oxide and methane emissions across multiple species and provinces in China. This study established a coupled provincial inventory for 2013–2023 and applied the Logarithmic Mean Divisia Index (LMDI) to identify socioeconomic drivers. Results show that NH₃ emissions declined slightly from ~4.1 Tg in 2013 to 3.95 Tg in 2023 (−3.7%), while N₂O increased from 2.1 to 2.3 Tg (+9.5%) and CH₄ rose from 3.1 to 4.2 Tg (+35%). Consequently, the aggregated global warming potential increased by ~24% (from ~1100 to ~1370 Tg CO₂-eq). Hogs were identified as the dominant contributor across gases. High-emission provinces contributed disproportionately, whereas metropolitan and western provinces reported marginal levels. LMDI decomposition revealed that affluence and technological intensification were the main drivers of growth, partially offset by production efficiency and labor decline. This study provides one of the first integrated multi-gas, multi-species, and region-specific assessments of livestock manure emissions in China, offering insights into targeted mitigation strategies that simultaneously support carbon neutrality and air quality improvement. Full article

Nitrous oxide (N₂O) is a potent greenhouse gas with a global warming potential > 310 times that of CO₂. Owing to its rapid increase in atmospheric concentrations from industrial emissions, N₂O poses increasing environmental concerns. Among the various N₂O abatement technologies, catalytic decomposition can directly convert N₂O into harmless N₂ and O₂ without generating secondary pollutants. In this study, Co₃O₄ spinel catalysts were synthesized using a polymer-assisted precipitation method, using polyvinyl alcohol, polyvinylpyrrolidone, or polyethylene glycol (PEG) as N₂O decomposition catalysts. The PEG-mediated synthesis method yielded the most active catalyst with superior N₂O decomposition efficiency. Structural and surface analyses confirmed that PEG facilitated the formation of Co²⁺-enriched surface sites and abundant oxygen vacancies, which are crucial active sites for N₂O adsorption and activation. Moreover, these features improved the redox properties and electron transfer behavior of the resulting catalyst. In particular, the PEG-derived 5Co₃O₄/CeO₂ catalyst exhibited enhanced N₂O decomposition activity and stability even in the presence of coexisting N₂O and O₂, highlighting its potential for real-world applications. This study provides an effective synthetic route for Co₃O₄-based catalysts and potential opportunities for wide applications in industrial N₂O removal. Full article

Soil organic nitrogen (SON) positively influences crop productivity, greenhouse gas (GHG) emissions, and sustained nitrogen (N) supply. Herein, we observed the effect of different treatments; no fertilizers (CK), chemical fertilizers (nitrogen, phosphorus, and potassium (NPK)), organic manure, and NPK + OM (NPKOM). This study was performed in a randomized complete block design (RCBD) with three replications. The results indicated that NPKOM treatment significantly decreased the nitrous oxide (N₂O) emissions by 19.97% and 17.47% compared to NPK in both years. This was linked with improved soil nutrient availability, soil organic carbon, soil organic nitrogen (SON) storage (10.06% and 12.38%), SON sequestration (150% and 140%), increased soil particulate (44.11% and 44%), and mineral-associated organic N (26.98% and 26.47%) availability. Furthermore, NPKOM also enhanced nitrate reductase (NR: 130% and 112%), glutamine synthetase (GS: 93% and 88%), sucrose phosphate synthase (SPS: 79% and 98%), SSs (synthetic direction; 57% and 50%), and decreased SSs activity in the decomposition direction (18% and 21%). This, in turn, inhibited the decomposition of sucrase and enhanced starch conversion into carbohydrates, thus leading to an increase in rice yield and a decrease in N₂O emissions. All fertilizations, particularly NPKOM, significantly enhanced grain protein contents by increasing N uptake and its availability. Therefore, NPKOM is an effective practice to enhance rice productivity, and SON sequestration and mitigate the N₂O emissions and subsequent climate change. Full article

The global production of brewers’ spent grains (BSG) is 37 million tons yearly. Composting represents an eco-friendly method to manage and valorize organic by-products in a circular economy model. This project aims to compare two BSG bin-composting mixtures (BSG and wheat straw with pig slurry solid fraction, MIX1, or sheep manure, MIX2) and approaches (manual turning, MT, and static composting, ST). The two mixtures’ physicochemical characteristics and greenhouse gas (GHG) emissions were assessed during the process. The evolution of physicochemical properties is reported in detail. Headspace samples of GHG emissions were collected and analyzed with gas chromatography coupled with specific detectors. Carbon dioxide (CO₂) emissions were 34.3 ± 0.03 and 31.0 ± 0.06 g C kg⁻¹ fresh matter (FM) for MIX1-MT and MIX2-MT, and 28.8 ± 0.01 and 31.2 ± 0.02 g Ckg⁻¹ FM for MIX1-ST and MIX2-ST. Methane emissions were negligible (all conditions < 0.086 ± 0.00 mg C kg⁻¹ FM). Nitrous oxide (N₂O) emissions from composting are affected by the substrate, bulking material, pile dimension, and manure. Particularly, the total emissions of N₂O, estimated as CO₂ equivalents, were 45.8 ± 0.2 and 63.0 ± 0.4 g CO₂ eq kg⁻¹ FM for MIX1-MT and MIX1-ST, respectively. In both composting approaches, MIX2 showed a low CO₂ equivalent (1.8 ± 0.02 and 9.9 ± 0.05 g CO₂ eq kg⁻¹ FM for MT and ST), likely due to incomplete decomposition. The bin-composting process represents a solution for recycling and reusing organic waste and livestock manure in small to medium-sized breweries. The solid fraction of the pig slurry resulted in the most suitable manure. Full article

Although various studies on nitrous oxide as a prospective green propellant have been recently explored, a polyethylene nitrous oxide catalytic decomposition hybrid thruster was barely demonstrated due to an inordinately high catalyst preheating time of a heater, which led to the destruction of components. Therefore, hydrogen peroxide was used as a preheatant, a substance to preheat, with a dual-catalyst bed. The thruster with polyethylene (PE) as a fuel, N₂O as an oxidizer, H₂O₂ as the preheatant, Ru/Al₂O₃ as a catalyst for the oxidizer, and Pt/Al₂O₃ as a catalyst for the preheatant was arranged. A preheatant supply time of 10 s with a maximum catalyst bed temperature of more than 500 °C and without combustion and an oxidizer supply time of 20 s with a burning time of approximately 15 s were decided. Because the catalyst bed upstream part for decomposing the preheatant was far from the post-combustion chamber, the post-combustion chamber pressure increased and the preheatant mass flow rate decreased after a hard start during the preheatant supply time. Moreover, because the catalyst bed upstream part primarily contributed to preheating, the maximum catalyst bed temperature was less than the decomposition temperature of the preheatant during the preheatant supply time. Additionally, because the catalyst bed downstream part for decomposing the oxidizer was far from the post-combustion chamber, the post-combustion chamber pressure decreased and then increased during a transient state in the oxidizer supply time. Full article

Straw returning (R) combined with the application of a decomposition agent (RD) can increase crop yield and soil carbon (C) storage. However, the effect of RD on soil nitrous oxide (N₂O) emissions in tropical areas remains poorly understood. In this study, an in situ experiment was performed under different water management strategies (long-term flooding or alternate wetting and drying) with the R and RD treatments to evaluate soil N₂O emissions and rice yield. The SOC and TN contents were significantly lower under the RD treatment than under the R treatment. The R treatment significantly increased rice yield; however, the yield was further significantly increased under the RD treatment. The soil N₂O emissions and yield-scaled N₂O emissions were higher under the R treatment than under the no-straw-returning treatment. However, the RD treatment greatly reduced soil N₂O emissions and yield-scaled N₂O emissions under various water management strategies compared with those under the R treatment. Moreover, yield-scaled N₂O emissions were lower in the RD treatment than in the control. The soil N₂O emissions and yield-scaled N₂O emissions were distinctly higher under alternate wetting and drying than under long-term flooding. Our results indicated that long-term flooding and straw returning with decomposition agents can effectively increase rice yield and reduce soil N₂O emissions in tropical areas. Full article

Anesthetic gases represent a small but significant portion of the environmental impact of health care in many countries. These compounds include several fluorocarbons commonly referred to as “fluranes”. The fluranes are greenhouse gases (GHG) with global warming potentials in the hundreds to thousands and are also PFAS compounds (per- and polyfluorinated alkyl substances) according to at least one definition. Nitrous oxide (N₂O) is sometimes used as an adjunct in anesthesia, or for sedation, but has a significant stratospheric ozone depletion potential as well as GHG effects. Reducing emissions of these compounds into the environment is, therefore, a growing priority in the health care sector. Elimination or substitution of the highest impact fluranes with alternatives has been pursued with some success but limitations remain. Several emission control strategies have been developed for fluranes including adsorption onto solids, which has shown commercial promise. Catalytic decomposition methods have been pursued for N₂O emission control, although mixtures of fluranes and N₂O are potentially problematic for this technology. All such emission control technologies require the effective scavenging and containment of the anesthetics during use, but the limited available information suggests that fugitive emissions into the operating room may be a significant route for unmitigated losses of approximately 50% of the used fluranes into the environment. A better understanding and quantification of such fugitive emissions is needed to help minimize these releases. Further cost–benefit and techno-economic analyses are also needed to identify strategies and best practices for the future. Full article

The production of nitric acid represents the primary source of nitrous oxide (N₂O) emissions. During pilot-scale studies of N₂O reduction on a low-temperature catalyst on nitric acid plants, it was observed that increasing the concentration of NH₃ resulted in a decrease in the degree of N₂O decomposition. This suggested that N₂O was formed by the oxidation of NH₃. Measurements at different temperatures, conducted after the N₂O reduction trials, resulted in the N₂O concentration at the inlet equal to the concentration at the outlet, indicating catalyst deactivation. To identify the causes of deactivation, the physicochemical properties of the catalyst were investigated. XRF analysis revealed the presence of sulfur. The results suggest the necessity of removing sulfur from the raw gas before the reduction of N₂O on the low-temperature catalyst in practical applications. Full article

Nitrous oxide (N₂O) is an industrial waste gas (e.g., from the production of adipic acid), which damages the ozone layer and causes the greenhouse effect. Density functional theory calculations were employed to investigate the mechanism of direct catalytic decomposition of N₂O and selective catalytic reduction (SCR) of N₂O by CO over Fe-ZSM-5 zeolites. Two stable Fe-active sites with six-membered ring structures on Fe-ZSM-5 were considered. The calculations indicate that the decomposition of N₂O is affected by the coordination environment around Fe and can occur through two reaction pathways. However, there is invariably a more considerable energy hurdle for the initiation of the second stage of N₂O decomposition. When CO participated in the reaction, it showed good reactivity and stability, the reaction energy barriers of the rate-limiting step were reduced by roughly 20.57 kcal/mol compared to the direct catalytic decomposition of N₂O. CO exhibited a superior electron-donating ability and orbital hybridization performance during the reaction, which enhanced the cyclicity of the N₂O reduction catalytic process. Our calculations confirmed the significant role of CO in N₂O reduction over Fe-ZSM-5 observed in previous studies. This study provides a valuable theoretical reference for exploring CO-SCR methods for N₂O reduction over Fe-based zeolite catalysts. Full article

Natural montane peatlands are generally not a significant source of nitrous oxide (N₂O) due to environment limitations, including phosphorus (P) scarcity and temperature lowness. Phosphorus enrichment and warming caused by global change are altering these limitations, and are likely to increase the source function of N₂O. However, the combined effects of P addition and warming on N₂O fluxes and biotic/abiotic factors in peatlands are still uncertain. To address this, we investigated the long-term (12 yrs) effects of P addition (5 and 10 kg ha⁻¹ yr⁻¹) and its interaction with warming on N₂O fluxes in a peatland. The results showed that although long-term P addition did not significantly affect the source/sink function of N₂O in the peatland, it stimulated enzyme activities and promoted peat decomposition. However, warming amplified the effect of P addition to increase N₂O emissions by stimulating enzyme activities and changing soil stoichiometry, so even turned the peatland into a significant source of N₂O with an emission of approximate 100 g m⁻² during the growing season. Our study suggests that P enrichment against the current background of global warming will enhance the possibility of strong N₂O emissions in montane peatlands, which may increase the risk that global warming will be further aggravated. Full article