Search Results (457)

Conventional nitrogen fertilization in a maize cropping system enhances the soil’s methane (CH₄) sink but exacerbates emissions of nitrous oxide (N₂O) and nitric oxide (NO). This study demonstrates that conventional nitrogen application (UN) increased CH₄ uptake by 154%, while elevating N₂O and NO emissions by 190% and 301%, respectively, compared to zero nitrogen plots (N0). Fertilization fundamentally reconfigured the regulatory mechanisms governing gas fluxes: under UN, fluxes were controlled by a complex interplay of nitrogen substrates, carbon availability, moisture, and temperature, whereas under N0, CH₄ uptake exhibited significantly enhanced temperature sensitivity (with Q₁₀ increasing from 1.06 to 7.54) and nitrogen oxide emissions became more dependent on native ammonium and extractable organic carbon. Crucially, nitrogen withdrawal reduced soil ammonium by 37.1% without altering non-nitrogen soil properties, including temperature, moisture, and labile carbon pools. Collectively, these findings are consistent with the concept of nitrogen saturation under conventional fertilization rates. Optimizing these rates presents a significant opportunity to mitigate greenhouse gas emissions and air pollution while improving nitrogen use efficiency, thereby aligning agricultural production with climate goals and public health objectives without destabilizing short-term soil function. Full article

Over the past few decades, the discovery of novel microbial processes, biochemical reactions, and previously uncharacterized microorganisms has significantly enhanced our understanding of nitrogen (N) cycling across terrestrial and aquatic ecosystems, including engineered environments such as wastewater treatment systems. These scientific advancements are catalyzing a paradigm shift toward treatment strategies that are not only energy-efficient and cost-effective, but also environmentally sustainable, with the added benefit of mitigating greenhouse gas emissions. The current review highlights recent breakthroughs in microbial N cycling, with particular emphasis on their practical applications in wastewater treatment. Emerging processes, such as nitrous oxide (N₂O) mitigation, electro-anammox, ferric iron-dependent ammonium oxidation (Feammox), and complete ammonia oxidation (comammox), offer promising strategies for sustainable and low-energy N removal. Nevertheless, a significant challenge persists in translating these laboratory-scale innovations into full-scale, real-world applications, especially within decentralized treatment infrastructures. Bridging this gap is essential for realizing robust, low-carbon, and sustainable wastewater management systems in the decades to come. Full article

Atmospheric greenhouse gases (GHGs) affect Earth’s radiation balance and are the primary drivers of climate change. This study analyzed the spatiotemporal variability of carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O) at domestic World Meteorological Organization/Global Atmosphere Watch (WMO/GAW) sites located at Anmyeondo (AMY), Jeju Gosan, and Ulleungdo, examining the local influences on GHG variations and comparing the relationships between gases. Long-term records from the AMY site were used to investigate temporal changes in CO₂–CH₄. The results showed that short-term variations were influenced by local emissions, sink processes, and anthropogenic signals, whereas medium-to-long-term variations displayed clear seasonality driven by vegetation and meteorological changes, with continuously increasing trends. The sites strongly reflected the effects of nearby point sources, and the ∆CO₂–∆CH₄ relationships revealed site-specific spatiotemporal differences. At AMY, 46–49% of top-quartile CO₂, CH₄, and N₂O enhancements occurred under easterly winds from nearby industrial and agricultural sources, whereas 14–16% under northwesterly flow indicated episodic transport from eastern China, highlighting the site’s combined exposure to domestic and foreign emissions. The observed strengthening long-term ∆CO₂–∆CH₄ correlation may be related to continuously increasing emissions in East Asia. However, uncertainties remain, owing to changes resulting from the 2012 instrument replacement and calibration scale. Overall, this study provides baseline insights into domestic GHG variability and offers fundamental information for understanding East Asian emissions and supporting climate policy. Full article

To clarify the role and mechanism of sod-seeding patterns in improving soil fertility and mitigating nitrous oxide (N₂O) emissions in peach orchards, we conducted a study since 2023. Taking clean tillage (CK) as the control, three sod-seeding patterns—Trifolium repens–Lolium perenne mixed sowing (TPr), T. repens single sowing (Tr), and L. perenne single sowing (Pr)—were tested to analyze soil physicochemical properties, nitrogen cycle functional genes, and N₂O emission-related genes, and to explore the driving mechanism of N₂O mitigation. Results showed that all three sod-seeding patterns significantly reduced soil pH and bulk density, increased soil electrical conductivity and mean aggregate size, and improved soil nutrient status compared with CK; TPr performed best, significantly enhancing soil enzyme activities related to carbon and nitrogen cycles. Sod-seeding patterns had no significant effect on genes involved in assimilatory nitrate reduction, denitrification, or nitrification, but significantly increased dissimilatory nitrate reduction (DNRA) and nitrogen degradation gene abundances, and reduced N₂O-producing gene (amoA + amoB, nirS + nirK) abundances. Field monitoring indicated TPr reduced N₂O emissions by 34.0%, 35.7%, and 41.0%, relative to CK, Pr, and Tr, respectively. Structural equation modeling revealed that sod-seeding reduced N₂O emissions mainly by decreasing soil NH₄⁺-N content and nirS + nirK abundance. In conclusion, sod-seeding patterns improve soil fertility and mitigate N₂O emissions in peach orchards, with TPr showing the best comprehensive benefits. Full article

Denitrification is conventionally viewed as a microbially mediated process driven by organic carbon, but the coupling of iron and nitrogen cycles represents a significant alternative pathway. Previous research focused on alkaline environments, leaving the direct reaction between ferrous iron (Fe²⁺) and nitrate (NO₃⁻) in acidic conditions poorly understood. This study investigated this process using in situ spectroscopy, examining the effects of the reactant ratio, time, temperature, and initial pH while monitoring nitrous oxide (N₂O) production. Results showed that the reaction was rapid, with most nitrate reduction within 5 min. The Fe²⁺ to NO₃⁻ molar ratio had a limited influence on efficiency. Temperature had a non-monotonic effect, optimal at 25 °C. The initial pH was the dominant control, with lower pH (e.g., 4.6) essential for high efficiency. Crucially, the process was confirmed as a significant source of N₂O under anoxic conditions. This work confirms Fe²⁺-driven nitrate reduction is a fast, acid-dependent process governed by pH and modulated by temperature. These findings revise our understanding of nitrogen fate and N₂O emissions and warn of potential underestimation of nitrate in samples containing Fe²⁺. Full article

Against the backdrop of global climate change, alterations in precipitation regimes—including the increasing frequency of extreme events—have become more widespread, exerting profound impacts on terrestrial ecosystems and reshaping greenhouse gas (GHG) emission dynamics in wetlands. Wetlands, as unique ecosystems formed at the interface of terrestrial and aquatic environments, play a critical role in regulating carbon source–sink functions. In this study, we conducted in situ field simulation experiments to examine how precipitation changes influence the seasonal fluxes of carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O) in the Wayan Mountain headwater wetlands, and further explored the regulatory effects of vegetation attributes and soil physicochemical properties on these fluxes. The results revealed that a moderate increase in precipitation (+25%) enhanced CO₂ emissions and vegetation growth while suppressing CH₄ and N₂O fluxes, indicating a positive ecosystem response to additional water supply. In contrast, extreme precipitation changes (+75% and −75%) weakened the coupling between GHG fluxes and soil factors, resulting in reduced CO₂ flux, amplified variability in CH₄ and N₂O emissions, and inhibited vegetation growth and community diversity. The dominant controls differed among gases: CO₂ was primarily regulated by soil carbon pools, CH₄ was highly sensitive to water availability, and N₂O was influenced by soil nitrogen, pH, and salinity. Overall, moderate increases in precipitation enhance the carbon sink capacity and community stability of alpine wetlands, whereas extreme hydrological fluctuations undermine ecosystem functioning. These findings provide important insights into carbon cycling processes and regulatory mechanisms of alpine wetlands under future climate change scenarios. Full article

A growing body of evidence indicates that freshwater bodies, particularly eutrophic systems, are significant sources of the greenhouse gases (GHGs) carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O). Unlike marine environments, freshwater systems are generally shallower and more directly influenced by terrestrial inputs, including nutrient enrichment, organic matter deposition, and steep redox gradients in both the water column and sediments. These conditions promote intense phytoplankton growth, including massive harmful cyanobacterial blooms (HCBs), and stimulate microbial processes that drive GHG production and release. This opinion article examines the biogeochemical mechanisms underlying these emissions and evaluates the potential of mitigation treatments to both enhance carbon sequestration and reduce CH₄ and N₂O emissions. We argue that effective control of HCBs, whether through nutrient load reduction or direct mitigation protocols, would not only provide communities with toxin-free water but also significantly lower GHG emissions from eutrophic waterbodies. As this is an opinion paper rather than a comprehensive review, we intentionally avoided citing widely accepted concepts, since doing full justice to the many excellent contributions across all relevant subfields would not be possible within the scope of this work. Full article

Owing to the natural texture of dam lakes, they emit nitrous oxide (N₂O) emissions. The main aim of this study was to reduce N₂O emissions resulting from dam lake treatment using malt dust-derived biochar. On average, a 21.1% reduction in N₂O emissions from dam lake treatment was reported using malt dust-derived biochar. The maximum nitrous oxide capture capacity corresponded to the malt dust-derived biochar fabricated at the minimum pyrolysis temperature (MD1). The statistical analysis results revealed that the optimum parameters were 4 mg/L of dissolved oxygen (DO) and 11 mg/L of nitrate (NO₃⁻) for the minimum N₂O emission. The highest correlation was calculated between N₂O emission and NO₃⁻ with the value of 97.99%. This study evidenced that agro-industrial biochar can adsorb N₂O from dam lakes. Full article

The agricultural sector has a significant impact on the global carbon cycle, contributing substantially to greenhouse gas (GHG) emissions through various practices and processes. This review paper examines the significant role of the agricultural sector in the global carbon cycle, highlighting its substantial contribution to GHG emissions through diverse practices and processes. The study explores the trends and spatial distribution of agricultural GHG emissions at both the global level and within the European Union (EU). Emphasis is placed on the principal gases released by this sector—methane (CH₄), nitrous oxide (N₂O), and carbon dioxide (CO₂)—with detailed attention to their sources, levels, environmental impacts, and key strategies to mitigate and control their effects, based on the latest scientific data. The paper further investigates emissions originating from livestock production, along with mitigation approaches including feed additives, selective breeding, and improved manure management techniques. Soil-derived emissions, particularly N₂O and CO₂ resulting from fertilizer application and microbial activity, are thoroughly explored. Additionally, the influence of various agricultural practices such as tillage, crop rotation, and fertilization on emission levels is analyzed, supported by updated data from recent literature. Special focus is given to the underlying mechanisms that regulate these emissions and the effectiveness of management interventions in reducing their magnitude. The research also evaluates current European legislative measures aimed at lowering agricultural emissions and promoting climate-resilient, sustainable farming systems. Various mitigation strategies—ranging from optimized land and nutrient management to the application of nitrification inhibitors and soil amendments are assessed for both their practical feasibility and long-term impact. Full article

Soil degradation, declining fertility, and rising greenhouse gas emissions highlight the urgent need for sustainable soil management strategies. Among them, biochar has gained recognition as a multifunctional material capable of enhancing soil fertility, sequestering carbon, and valorizing biomass residues within circular economy frameworks. This review synthesizes evidence from 186 peer-reviewed studies to evaluate how feedstock diversity, pyrolysis temperature, and elemental composition shape the agronomic and environmental performance of biochar. Crop residues dominated the literature (17.6%), while wood, manures, sewage sludge, and industrial by-products provided more targeted functionalities. Pyrolysis temperature emerged as the primary performance driver: 300–400 °C biochars improved pH, cation exchange capacity (CEC), water retention, and crop yield, whereas 450–550 °C biochars favored stability, nutrient concentration, and long-term carbon sequestration. Elemental composition averaged 60.7 wt.% C, 2.1 wt.% N, and 27.5 wt.% O, underscoring trade-offs between nutrient supply and structural persistence. Greenhouse gas (GHG) outcomes were context-dependent, with consistent Nitrous Oxide (N₂O) reductions in loam and clay soils but variable CH₄ responses in paddy systems. An emerging trend, present in 10.6% of studies, is the integration of artificial intelligence (AI) to improve predictive accuracy, adsorption modeling, and life-cycle assessment. Collectively, the evidence confirms that biochar cannot be universally optimized but must be tailored to specific objectives, ranging from soil fertility enhancement to climate mitigation. Full article

Wastewater nitrogen pollution is a serious environmental problem, and traditional treatment techniques are frequently constrained by their high energy requirements and operational complexity. The anaerobic ammonium oxidation (anammox) process combined with membrane bioreactor (MBR) technology (anammox-MBR) offers a practical and energy-efficient solution for the sustainable removal of nitrogen, further enhanced by its potential to minimize emissions of nitrous oxide (N₂O), a potent greenhouse gas with a global warming potential nearly 300 times that of carbon dioxide. This review outlines the most recent advancements in anammox-MBR systems, highlighting their ability to achieve nitrogen removal efficiencies of more than 70–90% and, in integrated systems with reverse osmosis, to recover up to 75% of the inflow as high-quality reusable water. Significant advancements such as high-rate activated sludge coupling, reverse osmosis integration, microaeration methods, and membrane surface modifications have decreased membrane fouling, accelerated startup times, and enhanced system stability. Despite these achievements, there are still issues that hinder widespread use, such as membrane fouling exacerbated by hydrophobic anammox metabolites, sensitivity to low temperatures (≤10 °C), and the persistent challenge of suppressing nitrite-oxidizing bacteria (NOB), which compete for the essential nitrite substrate. To enable cost-effective, energy-efficient, and environmentally sustainable large-scale applications, future research directions will focus on creating cold-tolerant anammox strains, advanced anti-fouling membranes, and AI-driven process optimization. Full article

Ammonia (NH₃) is a promising zero-carbon fuel to eliminate carbon footprint while the high autoignition temperature and low combustion rate of NH₃ remain challenging for practical implementation. Using dimethyl ether (DME) as pilot ignition fuel can substantially promote the reactivity of NH₃, thus paving the way for a widespread application of NH₃. In this study, the ignition process and nitrogen oxides (NO_x) emissions of the NH₃ liquid spray ignited by liquid DME spray were numerically investigated using Converge software. The ambient temperatures (T_amb) ranging from 900 K to 1100 K were used to mimic the in-cylinder temperature typically encountered in turbocharger engines. The effect of ammonia energy ratio (AER) and fuel injection timing was examined as well. It is found that only half of NH₃ is consumed at T_amb = 900 K while 97.4% of NH₃ is burned at T_amb = 1100 K. Nitric oxide (NO) and nitrogen dioxide (NO₂) formation also have strong correlation with T_amb and NO₂ is usually formed around the periphery of NO through these two channels HO₂ + NO = NO₂ + OH and NO + O(+M) = NO₂(+M). Extremely high nitrous oxide (N₂O, formed by NH + NO = H + N₂O) and carbon monoxide (CO) are produced with the presence of abundant unburned NH₃ at T_amb = 900 K. Additionally, increasing AER from 60% to 90% results in slightly declined combustion efficiency of NH₃ from 98.7% to 94%. NO emission has a non-monotonical relationship with AER owing to the ‘trade-off’ relationship between HNO concentration and radical pool at varying AERs. A higher AER of 95% leads to failed ignition of NH₃. Advancing DME injection not only increases combustion efficiency, but also reduces NO_x and CO emissions. 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

Biochar has been widely recognized for its potential to improve soil quality and mitigate greenhouse gas (GHG) emissions. A field experiment was conducted in a temperate climate zone of Slovakia on Haplic Luvisol and evaluated the long-term impact of biochar on soil properties, nitrous oxide (N₂O) emissions, and winter wheat (Triticum aestivum L.) yield. Biochar was applied in 2014 at rates of 0, 10, and 20 t ha⁻¹ and reapplied in 2018 at the same rates, combined with nitrogen (N) fertilization (0, 140, and 210 kg N ha⁻¹). Measurements, conducted from March to October 2021, showed that biochar improved soil water content, increased soil pH, and enhanced soil organic carbon content. However, the concentrations of NH₄⁺-N and NO₃⁻-N generally decreased across all the treatments compared to their respective controls. Biochar reapplication rate at 20 t ha⁻¹, especially combined with second level of N-fertilization, led to a significant reduction in cumulative N₂O emissions by 38.40%. Winter wheat yield was positively correlated with both biochar application (10 and 20 t ha⁻¹) and N levels (140 and 210 kg N ha⁻¹), but these differences were not statistically significant (p > 0.05). The positive effects of biochar on soil properties and yield declined over time, with no significant yield differences observed 7 years after the initial application and 3 years after reapplication. These findings suggest that while biochar can enhance soil conditions and reduce GHG emissions in the short term, its long-term effectiveness remains uncertain. Further research is needed to explore alternative biochar feedstocks, application methods, and strategies to sustain its benefits in agricultural systems. 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