Nitrous Oxide Emissions Research Articles

Combustion and emission characteristics of ammonia/methane partially premixed flame under ultrasonic excitation

ABSTRACT Ammonia (NH3) is emerging as a promising alternative fuel due to its high energy density and non-carbon mature. However, its large-scale industrial application is limited by its low reactivity and high nitrogen oxide (NOx) emissions during combustion. This paper investigated the effect of ultrasonic excitation on the combustion and emission characteristics of ammonia-methane-air partially premixed flame in a laboratory-scale burner. The flame temperature distribution was reconstructed using deflection tomography, and the flue gas composition was measured using a multicomponent gas analyzer. Numerical simulations were also conducted under the same experimental conditions. The experimental results showed that applying various ultrasonic frequencies resulted in a stable flame. The ultrasonic excitation resulted in changes in flame brightness and color, as well as a reduction in nitric oxide (NO) emission. Compared to the case without ultrasonic excitation, the maximum flame temperature increased by 17.85%, and NO emission decreased by 19.04% when excited with 20.2 kHz ultrasonic. The simulation results indicated that ultrasonic excitation enhanced the formation of free radicals. Single-point and rate of production (ROP) analysis further revealed that ultrasonic excitation enhanced the dehydrogenation of NHi and the polymerization between NH2 and NH. Additionally, ultrasonic excitation accelerated the direct reactions between NH and N with NO, leading to the formation of N2.

Processing poultry manure with black soldier fly technology lowers N2O and CO2 gas emissions from soil

Abstract Soil amended with poultry manure has many benefits including increased nutrient and organic carbon supply, enhanced soil structure and improved crop yield. However, the direct application of poultry manure to land can be associated with significant greenhouse gas (GHG) emissions. Black soldier fly (BSF) farming (Hermetia illucens) is an emerging technology that can convert manure into protein for animal feed, with larvae casting or frass produced as a waste by-product. BSF frass produced from poultry manure has potential to be used as a soil amendment with potentially lower GHG emissions than manure, but this has not been tested. To test this, a two-week microcosm experiment was used to investigate the impact of different soil amendments (poultry manure, BSF frass from poultry manure, urea and an unamended control) on nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) emissions. This study also aimed to examine bacterial populations associated with frass and poultry manure, as well as factors regulating their composition and the production of GHGs. Frass produced by BSF larvae fed poultry manure had up to 1.4 times lower N2O and 1.5 times lower CO2 cumulative emissions than poultry manure. Methane emissions were either minimal and/or balanced by oxidation across all treatments. Processing poultry manure with BSFL also altered the bacterial community composition and resulted in a proliferation of bacteria that were specific to BSFL frass, some of which have putative plant growth promoting properties. These results indicate that BSF technology holds promise for both reducing greenhouse gas emissions from poultry manure, as well as providing a sustainable soil amendment for productive agriculture.

Review of research studies on nitrous oxide emissions from manure-amended soils in Canada from 1990–2023

Review of research studies on nitrous oxide emissions from manure-amended soils in Canada from 1990–2023

Growing contribution to radiative forcing from China's on-farm nitrous oxide emissions requires more attention.

Agricultural systems are important emission sources of non-CO2 greenhouse gases (GHGs), including the relatively short-lived GHG methane (CH4). As a pivotal emitter, China's CH4 emissions have received wide attention. For the first time, this study applied an indicator of radiative forcing-based climate footprint (RFCF) to compare the climate impacts of China's on-farm non-CO2 GHG emissions including CH4 and nitrous oxide (N2O). We found that, with short atmospheric lifetime, CH4's contribution to RFCF has plateaued in 2011 at 3.37mWm-2 and achieved the goal of net zero increase to radiative forcing (RF) in 2017. However, the long-lived N2O emissions form an increasingly important proportion of the total RFCF at China's farm gate over time. The contribution from CH4 emissions to the total global on-farm RFCF experienced a downward trend, while that from N2O emissions has been trending upward during 1961-2021. It indicates the need of more attention on the long-lived climate forcer N2O in China. The RFCF indicator informs about whether progress is being made toward RF stabilization. It is recommended to widely apply the RFCF approach to re-examine and inform climate actions in China's agricultural systems as well as sectors with substantial biogenic CH4 emissions.

Extreme value theory analysis of high emitter trends across four US cities from 1995 to 2021.

Extreme value theory provides a direct means to characterize the distribution of high emitters within a vehicle fleet and calculate statistical confidence intervals for comparisons. Defining a "high emitter" as the maximum emitter in a random sample of N vehicles implies in the limit of large N that high emitters follow an extreme value distribution, comprised of three distinct domains. The analysis of over twenty years of roadside remote sensing emissions measurements in Chicago, Denver, Los Angeles and Tulsa reveals clear differences between gasoline vehicle high emitter distributions across pollutants (hydrocarbons (HC), carbon monoxide (CO) and nitric oxide (NO)), but very similar behavior across the four cities. As Federal emissions regulations became more stringent, HC and CO high emitters evolved from distributions bounded by the stoichiometric limits of HC and CO formation in an engine to progressively longer tailed distributions. In contrast, NO high emitter distributions have changed little over this time period. These distinct behaviors likely reflect differences in the failure mechanisms leading to high HC, CO, versus NO emissions. Whereas average HC, CO and NO fleet emissions fell dramatically over these two plus decades by factors of about 4, 6 and 7, respectively, mean high emitter emissions declined by less than half of these. The paper examines in detail similarities and differences in high emitter distributions versus pollutant, city and vehicle type, how these changed over a period of roughly twenty years and the policy implications that can be drawn.

Recent advances in low-temperature nitrogen oxide reduction: effects of electric field application.

This article presents a review of catalytic processes used at low temperatures to reduce emissions of nitrogen oxides (NOx) and nitrous oxide (N2O), which are exceedingly important in terms of their environmental impacts on the Earth. With conventional purification technologies, it has been difficult to remove these compounds under low-temperature conditions. By applying a catalytic process in an electric field for the three reactions of three-way catalysts (TWC), NOx storage reduction catalysts (NSR), and direct decomposition of N2O, we have achieved high catalytic activity even at low temperatures. By promoting ion migration on the catalyst surface, we have filled in the gaps in conventional catalytic technology and have opened the way to more efficient conversion of NOx and N2O.

How does the chemical composition of dung affect nitrous oxide and methane emissions in pasture soils?

There is an important gap in how variations in herbivore dung composition affect GHG emissions on pastures, especially due to differences in dry matter (DM) and nitrogen contents. Oversimplifications can compromise the accuracy of mitigation strategies. This study aims to address this gap by investigating how the chemical composition of dung from different species influences GHG emissions in pasture systems. The results showed that drier dung led to higher cumulative N₂O emissions. The highest emissions were observed from goat at 9.47 mg N-N₂O g⁻1 dry soil, followed by sheep at 5.95 mg N-N₂O g⁻1 dry soil, beef cattle at 5.44 mg N₂O g⁻1 dry soil, dairy cattle at 2.67 mg N₂O g⁻1 dry soil, and horse at 0.83 mg N₂O g⁻1 dry soil. It was observed that higher dung moisture content generally corresponded to increased CH₄ emissions, except for horse dung. The highest cumulative CH₄ emission was for dairy cattle dung (8.29 mg C-CH₄ g⁻1 dry soil), followed by beef cattle (3.89 mg C-CH₄ g⁻1 dry soil), sheep (2.32 mg C-CH₄ g⁻1 dry soil), goats (1.89 mg C-CH₄ g⁻1 dry soil), and horses (1.66 mg C-CH₄ g⁻1 dry soil). Principal Component Analysis illustrated that PC1, named as diet quality, explained 61.9% of the variance, was positively correlated with N₂O and negatively correlated with fiber content and C/N ratio, while PC2, named as acetrophic and hydrogenotrophic methanogenesis, explained 19.6% of the variance, linking VS to reduced CH₄ emissions. This study establishes relationships between manure chemical composition and GHG emissions, filling a fundamental knowledge gap and supporting the development of cause-and-effect models.

Assessment of N-related microbial processes in the soil of the Polesie National Park and adjacent areas, including reclaimed land.

Soil microorganisms are essential for maintaining ecosystem functionality, particularly through their role in the nitrogen (N) biogeochemical cycle. Thus, they also contribute to greenhouse gas emissions from soils. Microorganisms are sensitive indicators of soil health, as they respond rapidly to disturbances caused by factors like unsustainable agricultural practices or industrial activities, such as mining. These bioindicators are also useful for monitoring the effectiveness of environmental remediation treatments, such as soil reclamation. The study aimed to assess microbial activity related to the N cycle in soils across various habitats (peatland, grassland, forest, and field) under conservation management within the Polesie National Park (PNP), as well as in comparable conventionally managed habitats. Additionally, the effectiveness of soil reclamation was assessed using waste from the mining industry, specifically gangue. Significant differences were observed in the assessed activities, both between habitats and their locations, i.e., within the PNP and outside of it. It was found that microbial activity was lower in soils from the PNP area. This was likely a result of more intensive fertilizer application on soils not subject to the restrictions imposed by park regulations. It should be noted that urease activity, which can contribute to the adverse phenomenon of nitrogen loss from soils when elevated, similarly to nitrous oxide (N2O) emission, was lower in the soils from the park than in those located outside of it. Therefore, designating an area as a national park protects the soil environment from human pressures associated with intensive agriculture, thereby helping to maintain its homeostasis. Reclamation using gangue proved ineffective in restoring microbial activity in degraded soil to the level of cultivated soil outside the park. The assessed activities in the reclaimed soil were lower than the target levels. The results provided valuable information useful for environmental management decisions in terms of soil and air protection, as well as the use of waste for reclamation.

Diversified crop rotations exert a profound influence on the nosZI denitrifier community.

Agricultural soils are a significant contributor to global nitrous oxide (N2O) emissions, which is primarily driven by microbial nitrification and denitrification processes. Diversifying crop rotations can enhance soil nitrogen (N) utilization and influence N-cycling microbes, particularly the denitrifiers. Here, we evaluated the abundance, diversity, and community structure of soil denitrifiers by analyzing the denitrification genes (nirS, nirK, and nosZI) with a 14-year experiment of continuous and rotated crop systems. Compared to continuous cotton (C), crop rotations altered abundance of the nirS, nirK, and nosZI genes, but the responses varied among different rotation patterns (p<0.05). Diversified crop rotations decreased Shannon index of the nirS and nirK gene communities, while increased that of the nosZI gene communities. Diversified crop rotations greatly changed community structure of the nirS, nirK and nosZI gene communities (p<0.05). Among the responsive operational taxonomic units (OTUs), 2.62%, 2.52%, and 4.31% of the nirS, nirK, and nosZI genes were involved in the responses, respectively. Notably, a significant increase in OTUs belonged to N-fixing groups (i.e., Herbaspirillum and Rhodanobacter), while a decrease in OTUs affiliated to Achromobacter and Bosea was observed in diversified crop rotations. Furthermore, soil pH and C/N ratio correlated significantly with the nirS gene community structure (p<0.05), SOC and C/N ratio correlated with the nirK gene community (p<0.05), and soil pH, TN, NO3--N, and C/N ratio correlated with the nosZI gene community (p<0.05), respectively. In conclusion, our study demonstrates that long-term diversified crop rotations significantly altered the microbial communities related to denitrification, especially the nosZI gene community. These findings highlight the importance of diversified crop rotations in fostering soil denitrifiers communities that contribute to N₂O reduction, potentially supporting sustainable agricultural practices by reducing greenhouse gas emissions. However, future studies should be focus on both the nosZI and nosZII clades communities to offer a more complete picture of microbial contributions to soil N-cycling and N2O emission reduction.

Microbial community and functional shifts across agricultural and urban landscapes within a Lake Erie watershed.

The role of sediment microbial communities in regulating the loss and retention of nutrients in aquatic ecosystems has been increasingly recognised. However, in the Great Lakes, where nutrient mitigation focuses on harmful algal blooms, there are limited studies examining the fundamental role of water/sediment microbes in nutrient biogeochemical cycling. Little is understood in this regard considering the increase in anthropogenic pressure on in-stream biological processes impacting nutrient flux to lakes. In this study, metagenomic and metatranscriptomic approaches were used to investigate the microbial community and gene regulation. The study focused on nitrogen (N) metabolism in a nutrient-polluted watershed of Lake Erie in southwestern Ontario, Canada. Nutrients and microbial analyses of water and sediments were collected in 2020 and 2021 from Sturgeon Creek headwaters to the nearshore of Lake Erie. Results showed no significant shifts in community structure with nutrient concentrations or land use. Metabolically, active genes involved in denitrification (consisting of 32-53% of N metabolic transcripts) showed the highest expression within agricultural and wetland dominant locations. Based on active gene expression patterns, the urbanised location coinciding with peak nitrate (NO3-) concentrations showed the greatest potential for nitrous oxide (N2O) emission and nitrogen loss along this transect. In contrast to denitrification, direct nitrification (5-21% of N metabolic transcripts) increased two-fold approaching downstream and nearshore lake locations. Across this river-lake corridor, expression of key functional genes associated with N transformation showed strong correlation with the change in concentrations of aqueous NO3- and nitrite (NO2-) and the ratio of NO2-/NO3-. Our findings demonstrated a clear link between sediment microbial metabolism and overlying water chemistry in this lotic system. We suggest that future studies assessing nutrient mitigation consider sediment biogeochemical processes and N-metabolising bacteria, and their fundamental role and cooperative relationship with nutrient and hydrological dynamics of overlying waters.

Modeling nitrous oxide emission from full-scale hybrid membrane aerated biofilm reactors (MABR)

Modeling nitrous oxide emission from full-scale hybrid membrane aerated biofilm reactors (MABR)

Less toxic combined microplastics exposure towards attached Chlorella sorokiniana in the presence of sulfamethoxazole while massive microalgal nitrous oxide emission under multiple stresses

Less toxic combined microplastics exposure towards attached Chlorella sorokiniana in the presence of sulfamethoxazole while massive microalgal nitrous oxide emission under multiple stresses

The carbon footprint of Conservation Agriculture

ABSTRACT Proponents of Conservation Agriculture (CA) believe that by not tilling the soil, climate-friendly agriculture is achieved by reducing greenhouse gas emissions from agriculture and by storing atmospheric carbon in the soil. However, some scientists question climate benefits of CA. Literature shows that carbon storage through soil organic carbon (SOC) accumulation of up to 1 t ha–1 y–1 is possible without increasing nitrous oxide (N2O) emissions under a CA system. Opposing studies were flawed by analysing not complete CA systems and leaving out some of the principles. It is shown that each tillage operation releases up to 300 kg carbon dioxide equivalents (CO2e) per hectare, and each of the average annual 10 t ha–1 of eroded topsoil can emit additional 300 kg CO2e ha–1. A case study in Germany confirms these findings that with full application of CA the carbon footprint of agricultural food production can be significantly decreased, helping to mitigate climate change. It is concluded that net soil carbon storage is possible if all the principles of CA are consistently implemented. It is also concluded that together with other complementary production measures, CA has the potential to make agriculture carbon neutral.

Оценка экологической реакции агроценоза при мониторинговых наблюдениях продукционного процесса злаковых культур

The existing problems of climate change: an increase in the number of negative natural phenomena (droughts, floods); rising temperatures and energy use; increasing dependence on food imports. Adaptive crop production and the sustainability of agrocenoses in general requires an assessment of crop variability and has an important independent significance. In this work, a comprehensive assessment of the production process of spring barley in the conditions of microfield experience with the use of various types of fertilizers was carried out, as well as an assessment of the emission of nitrous oxide (N2O) in the crops of the studied crop by phenophases, depending on the time dynamics of environmental factors. Keywords: NITROUS OXIDE, INTENSIVE AGRICULTURAL TECHNOLOGIES, ENVIRONMENTAL MONITORING, SPRING BARLEY, GREENHOUSE GASES, ADAPTIVE AGRICULTURE, SUSTAINABLE AGROCENOSES

Sectoral Analysis of Electricity Consumption on Methane and Nitrous Oxide Emissions: A Case Study of Pakistan

The problem of environmental pollution is a burning issue in the current era. Many studies have been conducted on the relationship between environmental pollution and energy consumption, but there is rare literature on disaggregating sectors of energy consumption, especially focusing on electricity consumption that causes environmental pollution in the context of Pakistan. The study conducts quantitative research on the topic spanning from 1972-2022. Unit root was conducted, and as mixed integrating orders were found, I(0) and I(I) Autoregressive Distributive lag models were found appropriate for methodology. Furthermore, Causality was also conducted by applying Toda Yamamoto. Methane and Nitrous oxide emissions were found to have a long-run relationship. The most prominent sector in found contributing to pollution is the household sector, followed by industrial, commercial, and agriculture.

Assessing the influence of EGR on diesel pilot ignition combustion with methane/hydrogen blends in a single-cylinder compression ignition engine

This paper experimentally investigates the impact of EGR on the combustion performance and emissions of methane/hydrogen blends for the diesel pilot ignition (DPI) combustion strategy. Different speed/load cases were evaluated on a single-cylinder compression ignition engine for hydrogen energy shares ranging from 0% to 20%. As hydrogen was added to the premixed mixture, the combustion phasing (CA50) was held constant by either adjusting the pilot start of injection (SOI) timing or using EGR at constant intake pressure (varying premixed equivalence ratio). The experimental results show that the use of EGR at constant intake pressure with methane/hydrogen blends leads to lower unburned hydrocarbon (UHC), carbon-monoxide (CO), and nitric oxide (NO) emissions when compared to the methane-only baseline. Adiabatic flame temperature calculations were used to help explain the observed engine out nitric oxides (NOx) emissions trends. The UHC emissions, however, were significantly higher than the baseline split-injection diesel case due to incomplete combustion and crevice effects. Combustion efficiency improved without a thermal efficiency reduction with hydrogen addition, suggesting that substitution with hydrogen can be beneficial for dual-fuel compression ignition strategies that utilize natural gas. The decay rate for CH4 and H2 was more than linear, which is attributed to the chemical effects of hydrogen addition and EGR.

Effect of nano urea on greenhouse gas emissions in transplanted rice (Oryza sativa L.) ecosystems

The application of conventional nitrogen fertilizer (urea) to improve rice crop yield has a significant influence on soil methane (CH4) and nitrous oxide (N2O) emissions. An experiment was conducted at Tamil Nadu Agricultural University, Coimbatore, wetlands farm, during the summer of 2023. A Randomized Block Design (RBD) was used with 8 treatments and 3 replications to evaluate the impact of different nitrogen application strategies on greenhouse gas emissions, specifically methane and nitrous oxide in transplanted rice, including the varying nitrogen levels. The study aimed to improve rice growth and yield through foliar application of nano urea, focusing on the rice variety CO55 with a recommended dose of NPK (150:50:50 NPK kg/ha). The results indicated that applying 75 kg nitrogen/ha (50 % of the recommended dose) as basal through conventional urea, along with 3 nano urea foliar sprays at 20, 40 and 60 days after transplanting (T5), resulted in significantly lower methane and nitrous oxide emissions compared with 100 % of the recommended nitrogen dose i.e. 150 kg nitrogen/ha applied through conventional urea, with 25 % used at basal, active tillering, panicle initiation and heading stage (T1) and 150 kg nitrogen/ha i.e. 100 % recommended dose of nitrogen applied through conventional urea, with 50 % as basal and 2 top dressings of 25 % of the recommended dose of nitrogen (RDN) each at active tillering and panicle initiation (T2).

Impacts of Legacy and Contemporary Nitrogen Inputs on N2O and CO2 Emissions in Miscanthus and Maize Cultivated Soils

ABSTRACTNutrient inputs influence the sustainability of bioenergy crop production through contemporary (shortly after addition) and legacy effects (persisting over years) on microbial nitrogen (N) and carbon cycling, which contribute to greenhouse gas emissions. However, the relative importance of contemporary and legacy effects and how that could vary by crop functional types is poorly understood. Considering its rhizomatous roots and perennial growth, we hypothesized that Miscanthus × giganteus (M×g) would be more sensitive to legacy N fertilization and the historical context of its environment than an annual crop like maize. To test this hypothesis, we examined the effects of legacy and contemporary N inputs on nitrous oxide (N2O) and carbon dioxide (CO2) emissions, as well as key N cycling genes in soils where M×g and maize were grown. A 150‐day soil incubation experiment was conducted using soils from a long‐term M×g and maize fertility experiment with three historic N fertilization rates (0, 112, and 336 kg N ha−1 year−1) and a contemporary amendment (60 mg N kg−1) with negative control (0 mg N kg−1). We observed significant increases in cumulative N2O emissions in Mxg soils relative to maize soils, particularly at higher legacy fertilization rates, while contemporary N had no significant effect. Bacterial amoA gene abundance, which plays a significant role in nitrification in nutrient‐rich soils, also increased with higher legacy fertilization rates in M×g soils but was unaffected by the contemporary N. In maize soils, legacy and contemporary N did not significantly affect N2O emissions, but cumulative CO2 emissions and amoA gene abundance significantly increased. The abundances of norB genes were not significantly influenced by either legacy fertilization or contemporary N amendments in either soil. Our findings demonstrate the greater importance of fertilization history over contemporary N in mediating soil N2O emissions, particularly for perennial bioenergy crops.

Ammonia Combustion: Internal Combustion Engines and Gas Turbines

The quest for renewable energy sources has resulted in alternative fuels like ammonia, which offer promising carbon-free fuel for combustion engines. Ammonia has been demonstrated to be a potential fuel for decarbonizing power generator, marine, and heavy-duty transport sectors. Ammonia’s infrastructure for transportation has been established due to its widespread primary use in the agriculture sector. Ammonia has the potential to serve as a zero-carbon alternative fuel for internal combustion engines and gas turbines, given successful carbon-free synthesis and necessary modifications to legacy heat engines. While its storage characteristics surpass those of hydrogen, the intrinsic properties of ammonia pose challenges in ignition, flame propagation, and the emissions of nitrogen oxides (NOx) and nitrous oxide (N2O) during combustion in heat engines. Recent noteworthy efforts in academia and industry have been dedicated to developing innovative combustion strategies and enabling technologies for heat engines, aiming to enhance efficiency, fuel economy, and emissions. This paper provides an overview of the latest advancements in the combustion of neat or high-percentage ammonia, offering perspectives on the most promising technical solutions for gas turbines, spark ignition, and compression ignition engines.

Effects of Long-Term Nitrogen Fertilization on Nitrous Oxide Emission and Yield in Acidic Tea (Camellia sinensis L.) Plantation Soils

The responses of nitrous oxide (N2O) emissions to nitrogen (N) application in acidic, perennial agricultural systems, and the factors driving these emissions, remain poorly understood. To address this gap, a 12-year field experiment was conducted to investigate the effects of different N application rates (0, 112.5, 225, and 450 kg N ha−1 yr−1) on N2O emissions, tea yield, and the associated driving factors in a tea plantation. The study found that soil pH significantly decreased with long-term N application, dropping by 0.32 to 0.85 units. Annual tea yield increased significantly, by 148–243%. N application also elevated N2O emission fluxes by 33–277%, with notable seasonal fluctuations observed. N2O flux was positively correlated with N rates, water-filled pore space (WFPS), soil temperature (Tsoil), and inorganic N (NH4+-N and NO3−-N), while showing a negative correlation with soil pH. Random forest (RF) modeling identified WFPS, N rates, and Tsoil as the most important variables influencing N2O flux. The cumulative N2O emissions for N112.5, N225, and N450 were 1584, 2791, and 45,046 g N ha−2, respectively, representing increases of 1.33, 2.34, and 3.77 times compared to N0. The N2O-N emission factors (EF) were 0.35%, 0.71%, and 0.74%, respectively, and increased with higher N rates. These findings highlight the importance of selecting appropriate fertilization timing and improving water and fertilizer management as key strategies for mitigating soil acidification, enhancing nitrogen use efficiency (NUE), and reducing N2O emissions in acidic tea-plantation systems. This study offers a theoretical foundation for developing rational N fertilizer management practices and strategies aimed at reducing N2O emissions in tea-plantation soils.