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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]

Nitrous oxide (N2O) emissions are a serious global issue, with substantial evidence indicating that hydroclimate processes significantly contribute to these emissions. Forests, covering one-third of global land, are key in the water cycle and influence hydroclimate processes, which vary with climate, latitude, and forest types. The role of hydroclimate in regulating global forest N2O emission remains largely unknown. Our global analysis shows that hydroclimate factors dominate the latitudinal gradient of forest N2O fluxes, which decrease with latitude. N2O fluxes are highest in tropical forests, followed by temperate and boreal forests. Hydroclimate factors contribute 78.2% to N2O fluxes, while soil factors contribute 21.8%. Our results urgently call for future studies to investigate the relationship between N2O flux and hydroclimate factors like radiation, evapotranspiration, and vapor pressure deficits. Collectively, these findings highlight hydroclimate significant impact on N2O emissions and suggest incorporating these factors into predictive models for greater accuracy. [ABSTRACT FROM AUTHOR]

Aims: Nitrous oxide (N2O) plays an important role in global climate change. Plant expansion can alter soil nutrient cycling and greenhouse gas (GHG) fluxes but the effects of fine root litter mixing from plant expansion on litter decomposition, nutrient cycling, and GHG fluxes are poorly understood. Methods: To evaluate the impacts of fine root litter mixing from plant expansion on GHG budgets, we conducted an in situ study over sixteen months in Japanese cedar (Cryptomeria japonica) plantations experiencing moso bamboo (Phyllostachys edulis) expansions. Litter decomposition and N2O production were quantified in a full-factorial complete-randomized design by comparing fine root litter of Japanese cedar, moso bamboo or their mixtures, with or without nitrogen (N) addition. Results: We found that litter mixing accelerated decomposition, demonstrating a synergistic non-additive effect (19% increase in mass loss). This might have accelerated release of chemicals that inhibit microbial activities because litter mixtures had lower microbial biomass. Soil N2O emissions in the mixed litter treatment were 16.8% and 24.4% lower than those with only cedar or bamboo litter, respectively. N deposition promoted mass loss of mixed litter (28% increase in mass loss) and increased N2O emissions by 36.7%, 60.6% and 33.6% from cedar, mixed and bamboo litter treatments, respectively. Conclusion: The expansion of moso bamboo promotes the return of soil nutrients, reduces N2O emissions, and potentially mitigates GHG emissions. However, with increasing N deposition in the future, moso bamboo expansion will likely contribute to global warming. [ABSTRACT FROM AUTHOR]

The demand for biomass energy production in the Philippines has led to substantial rice husk ash (RHA) generation. We combined alternate wetting and drying (AWD) and varying RHA rates (10, 20, and 30 t ha–1) to evaluate the yield, water productivity (WP), and greenhouse gas (GHG) emissions in paddy rice for four cropping seasons (CS). We compared these treatments with continuous flooding (CF) and no RHA as controls. The RHA decreased N2O emissions by 8–22%, in the order of RHA30 > RHA20 > RHA10 relative to the control. The AWD had a marginal effect (P < 0.10) on CH4 emissions, with a 10% reduction relative to CF. While yields did not differ among treatments, AWD saved 39% water, and WP increased by 0.56 kg m–3 relative to CF. A significant interaction (P < 0.05) among water, RHA, and CS on N2O emissions was associated with rice stubble management in the first CS just after the harvest of the previous crop (dry incorporation), while the other seasons incorporated stubbles during wetland preparation. Although the highest RHA rate was likely to increase N2O emissions under AWD conditions, the global warming potential (GWP) was still significantly lower (P < 0.05) in the first CS in either water management by up to 15 times lower compared to other CS at all RHA rates. Our results indicated that the primary RHA effects mitigated N2O emissions, while AWD had only marginal effects on CH4 emissions but maintained grain yield under our experimental conditions. The low total GWP in the first CS suggests that the additional mitigation measures of RHA application and water management need to be associated with the proper management of rice stubbles first. [ABSTRACT FROM AUTHOR]

This letter, published in the Journal of Anesthesia, Analgesia & Critical Care, discusses the environmental impact of anesthetic gases (AG) and the awareness of anesthesiologists regarding this issue. The study found that AG accounted for a significant portion of greenhouse gas emissions in healthcare systems. The researchers analyzed data from their university center and found that AG use did not decrease over the years, despite recommendations to consider alternative methods. They also conducted a survey among anesthesiologists and found that while most believed total intravenous anesthesia (TIVA) could substitute AG in a significant number of cases, many were unaware of the environmental impact of AG. The study suggests that there is room for improvement in reducing AG use and increasing awareness among anesthesiologists. [Extracted from the article]

Rice is the staple food in Sri Lanka, and over 15% of the national land is allocated for rice cultivation. Greenhouse gas (GHG) emissions from rice fields account for 10% of national GHG emissions. The country has committed to reducing its emissions by 14.5% between 2010 and 2030 and achieving net zero emissions by 2060. In 2021, the country banned agro-fertilizer imports and opted for organic fertilizers, leading to a notable decrease in production and posing challenges to food security. However, the impact of adopting compost fertilizers alone remains unexplored. This study evaluated the global warming impact of two organic fertilizer strategies: switching to compost fertilizer instead of urea and applying rice straw compost instead of retaining crop residue. We applied the Denitrification and Decomposition model (DNDC 95) to rice field management data from Sri Lanka's Mahaweli H agricultural region. Simulations suggest that both strategies would increase the global warming potential of rice fields, mainly owing to elevated N2O emissions. This outweighs the mitigation benefits of avoiding crop residue retention and adding organic carbon through compost. Overall, our results point to the potential risk of shifting exclusively to compost-based fertilizers. [ABSTRACT FROM AUTHOR]

In this paper, we propose a new extension of the Vasicek model to the multivariate case and analyze its characteristics, including its probability density function, marginal trends, and correlation functions. We also conduct statistical estimation on the model, including likelihood parameter estimation and estimation of the marginal trend and correlation functions. To validate the effectiveness of our proposed model, we use simulation studies and examine the goodness of fit. Additionally, we apply our model to a bivariate case involving the analysis of CO 2 and N 2 O concentrations. We describe the data, fit the bivariate Vasicek stochastic diffusion model, and compare it with the univariate case. Finally, we summarize our findings and discuss the potential applications of our proposed model. [ABSTRACT FROM AUTHOR]

In recent years, reports of health problems associated with nitrous oxide consumption have significantly increased. In Germany, nitrous oxide (N2O) is easily available in cartridges without legal restrictions. The main reason for its popularity in the party scene are the euphoric, psychedelic effects of the gas. In addition to severe and sometimes irreversible health problems associated with long-term use of nitrous oxide, e.g., anemia and nerve damage, life-threatening or fatal consequences of acute nitrous oxide consumption can also occur: accidents under the influence of nitrous oxide, pneumothorax, pneumopericardium and shock due to an explosive increase in airway pressure when inhaled directly from the cartridge. But the most common cause of severe complications is asphyxia as the gas is usually inhaled pure from large balloons and without oxygen. The resulting hypoxia during use may be perpetuated by the diffusion hypoxia that occurs during the reoxygenation period. Nitrous oxide as a cause in accidental or intoxication events is usually not detectable but can only be identified as a trigger based on the patient's history or the circumstances. Acute medical treatment is symptomatic. [ABSTRACT FROM AUTHOR]

Climate change has been intensifying soil drying and rewetting cycles, which can alter the soil microbiome structure and activity. Here we hypothesized that a soil drying-rewetting cycle enhances biodegradation and, hence, decreases the effectiveness of nitrification inhibitors (NIs). The effectiveness of DMPP (3,4-Dimethylpyrazole phosphate) and MP + TZ (3-Methylpyrazol and Triazol) was evaluated in 60-day incubation studies under a drying and rewetting cycle relative to constant low and high soil moisture conditions (40% and 80% water-holding capacity, WHC, respectively) in two different textured soils. The measurements included (i) daily and cumulative N2O-N emissions, (ii) soil NH4+-N and NO3−-N concentrations, and (iii) the composition of bacterial soil communities. Application of DMPP and MP + TZ reduced the overall N2O-N emissions under drying-rewetting (-45%), as well as under 40% WHC (-39%) and 80% WHC (-25%). DMPP retarded nitrification and decreased N2O-N release from the sandy and silt loam soils, while MP + TZ mitigated N2O-N production only from the silt loam soil. Unexpectedly, between days 30 and 60, N2O-N emissions from NI-treated soils increased by up to fivefold relative to the No-NI treatment in the silt loam soil at 80% WHC. Likewise, the relative abundance of the studied nitrifying bacteria indicated that the NIs had only short-term effectiveness in the silt loam soil. These results suggested that DMPP and MP + TZ might trigger high N2O-N release from fine-textured soil with constant high moisture after this short-term inhibitory effect. In conclusion, DMPP and MP + TZ effectively reduce N2O-N emissions under soil drying and rewetting. [ABSTRACT FROM AUTHOR]

Coastal nutrient loads from point sources such as rivers are mostly well-monitored. This is not the case for diffuse nutrient inputs from coastal catchments unconnected to rivers, despite the potential for high inputs due to intensive land use. The German Baltic Sea coastline consists of numerous peatlands that have been diked and drained. However, some of the dikes have been removed in order to re-establish the hydrological connection to the Baltic Sea, restore local biodiversity, and promote natural CO2 uptake. Since these peatlands were used for agriculture, their rewetting may release accumulated nutrients, leading to nutrient export into the Baltic Sea and intensified coastal eutrophication. Data on these potential nutrient exports are mostly lacking. Therefore, this study investigated nutrient exports from two former agricultural, coastal peatlands: Drammendorfer Wiesen, rewetted in 2019, and Karrendorfer Wiesen, rewetted in 1993. Nutrients (NO3–, NO2–, NH4+, PO43–), nitrous oxide (N2O), particulate organic matter (POM, comprising POC and PON; δ13C-POC), chlorophyll-a, and nitrification rates were analyzed in surface water and porewater sampled weekly to monthly in 2019 and 2020 to compare the effects of different time scales after rewetting on nutrient cycling and potential exports. NH4+, NO2−, and PO43− concentrations were higher in the porewater than in the overlying water at both sites, while nutrient concentrations were generally higher at the recently rewetted Drammendorfer Wiesen than at the Karrendorfer Wiesen. NO3− concentrations in porewater, however, were lower than in the overlying water, indicating NO3− retention within the peat, likely due to denitrification. Nitrification rates and N2O concentrations were generally low, except for a high N2O peak immediately after rewetting. These results suggest that denitrification was the dominant process of N2O production at the study sites. Both peatlands exported nutrients to their adjacent bays of the Baltic Sea; however, N exports were 75% lower in the longer-rewetted peatland. Compared to major Baltic Sea rivers, both sites exported larger area-normalized nutrient loads. Our study highlights the need to monitor the impact of rewetting measures over time to obtain accurate estimates of nutrient exports, better assess negative effects on coastal waters, and to improve peatland management. [ABSTRACT FROM AUTHOR]

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In the current era, it has become essential to move toward highly efficient and low-emission engines as the norms for automobile emissions are very stringent and closely monitored; moreover, it also tends to be more strictly regulated in the future. The aim of this experimental work is to optimize engine efficiency as well as reduce emissions to the maximum using oxygen-enriched air. An onboard oxygen generator can provide oxygen-enriched air instead of an oxygen cylinder, as the latter one is prone to cause safety issues. In this experimental study, oxygen is obtained through generator and is sent to the engine's intake manifold, where the atmospheric air merges with it. The parameters of combustion, performance, and emission of this oxygen-enriched air were examined in a constant-speed compression ignition engine. The result shows that the engine's brake thermal efficiency increased by 5.4% at 25% of brake power as compared to the thermal efficiency attained in atmospheric air combustion. Similarly, brake-specific fuel consumption also decreased in the oxygen-enriched combustion process. The emissions of hydrocarbon and carbon monoxide also decreased to 18.8% and 33.3%, respectively, for 25% of the brake power; notably, the smoke emissions reduced drastically to 32% at the same brake power. The oxides of nitrogen emission, however, increased with the air's oxygen content. [ABSTRACT FROM AUTHOR]

The rising aquaculture industry has induced an increase in aquaculture waste, calling for advanced methods to recycle waste in the context of the circular economy. Here, we review methods to treat aquaculture wastewater such as the biofloc technique, aquaponic-aquaculture, rice-fish co-culture, microalgae culture, algal–bacterial culture, membrane and moving bed bioreactors, and electrochemical techniques. We discuss nitrogen cycling, resources recovery, and nitrous oxide emission and mitigations. We observed that aquaculture wastewater irrigation allows for enhanced plant biomass, and biofloc technology improves fish biomass. Nitrogen removal processes, including anammox and partial nitrification, show improved performance. Nitrous oxide emission is mainly dependent on the total ammonia and nitrite concentration. [ABSTRACT FROM AUTHOR]

Dissolved oxygen (DO) levels and carbon-to-nitrogen (C/N) ratio affect nitrous oxide (N2O) emissions by influencing the physiological and ecological dynamics of nitrifying and denitrifying microbial communities in activated sludge systems. For example, Nitrosomonas is a common N2O producing nitrifying bacteria in wastewater treatment plants (WWTPs), and DO conditions can affect the N2O production capacity. Previous studies have reported N2O emission characteristics under adequate DO and C/N conditions in A/O WWTPs. However, in actual operation, owing to economic and managerial factors, some WWTPs have a long-term state of low DO levels in oxic tanks and low influent C/N. Research on N2O emission characteristics in low DO-limited and low C/N ratio WWTPs is limited. This study investigated N2O emissions and the corresponding shifts in microorganisms within an anoxic–oxic (A/O) WWTP over 9-month. Quantitative PCR was used to assess the abundance of ten functional genes related to nitrification and denitrification processes, and high-throughput sequencing of the 16S rRNA gene was employed to determine the composition change of microorganisms. The findings revealed that 1) the average N2O emission factor was 1.07% in the studied WWTP; 2) the DO-limited oxic tank primarily contributed to N2O; 3) NO2–, TOC, and C/N ratios were key factors for dissolved N2O in the aerobic tank; and 4) Nitrosomonas and Terrimonas exhibited a robust correlation with N2O emissions. This research provides data references for estimating N2O emission factors and developing N2O reduction policies in WWTPs with DO-limited and low C/N ratios. [ABSTRACT FROM AUTHOR]

Agricultural nitrous oxide (N2O) emission reduction strategies are required given the potency of N2O as a greenhouse gas. However, the growing influence of N2O on stratospheric ozone (O3) with declining stratospheric chlorine means the wider atmospheric impact of N2O reductions requires investigation. We calculate a N2O emission reduction of 1.35 TgN2O yr-1 (~5% of 2020 emissions) using spatially separate deployment of nitrification inhibitors ($70–113 tCO2e−1) and crushed basalt (no-cost co-benefit) which also sequesters CO2. In Earth System model simulations for 2025–2075 under high (SSP3-7.0) and low (SSP1-2.6) surface warming scenarios, this N2O mitigation reduces NOx-driven O3 destruction, driving regional stratospheric O3 increases but with minimal impact on total O3 column recovery. By 2075, the radiative forcing of the combined N2O and CO2 reductions equates to a beneficial 9–11 ppm CO2 removal. Our results support targeted agricultural N2O emission reductions for helping nations reach net-zero without hindering O3 recovery. [ABSTRACT FROM AUTHOR]

Denitrification and anaerobic ammonium oxidation (anammox) are key processes for nitrogen removal in aquaculture, reducing the accumulated nitrogen nutrients to nitrogen gas or nitrous oxide gas. Complete removal of nitrogen from aquaculture systems is an important measure to solve environmental pollution. In order to evaluate the nitrogen removal potential of marine aquaculture ponds, this study investigated the denitrification and anammox rates, the flux of nitrous oxide (N2O) at the water–air interface, the sediment microbial community structure, and the gene expression associated with the nitrogen removal process in integrated multi-trophic aquaculture (IMTA) ponds (Apostistius japonicus-Penaeus japonicus-Ulva) with different culture periods. The results showed that the denitrification and anammox rates in sediments increased with the increase of cultivation periods and depth, and there was no significant difference in nitrous oxide gas flux at the water–air interface between different cultivation periods (p > 0.05). At the genus and phylum levels, the abundance of microorganisms related to nitrogen removal reactions in sediments changed significantly with the increase of cultivation period and depth, and was most significantly affected by the concentration of particulate organic nitrogen (PON) in sediments. The expression of denitrification gene (narG, nirS, nosZ) in surface sediments was significantly higher than that in deep sediments (p < 0.05), and was negatively correlated with denitrification rate. All samples had a certain anammox capacity, but no known anammox bacteria were found in the microbial diversity detection, and the expression of gene (hzsB) related to the anammox process was extremely low, which may indicate the existence of an unknown anammox bacterium. The data of this study showed that the IMTA culture pond had a certain potential for nitrogen removal, and whether it could make a contribution to reducing the pollution of culture wastewater still needed additional practice and evaluation, and also provided a theoretical basis for the nitrogen removal research of coastal mariculture ponds. [ABSTRACT FROM AUTHOR]

Nitrous oxide (N2O) is a long-lived stratospheric ozone-depleting substance with an atmospheric lifetime of 116 years. It is also a greenhouse gas with a global warming potential value of about 310. Due to its high kinetic stability and thermal decomposition temperature exceeding 1000°C, the treatment and recovery of nitrous oxide pose significant engineering and climate challenges. In this study, we introduce a Cu–Fe oxide catalyst that demonstrates efficient and low-temperature conversion of N2O to N2 using readily available reductant CO. The oxide catalyst was synthesized by a solvothermal method and a "from bottom to top" technique. Characterizations by X-ray diffraction (XRD), CO temperature-programmed desorption (C-O‑TPD), scanning electron microscopy (SEM), and BET indicate that the catalyst with weaker CO adsorption sites, fewer strong CO adsorption sites, suitable particle size, good dispersion and high specific surface area performs excellent reaction activity in the reduction of N2O to N2 by CO. The active site of Cu is stronger, and the addition of Fe can promote dispersion of the Cu active site and increase the exposure to the active site. A new approach has been proposed to address nitrous oxide emissions, a greenhouse gas with high thermodynamic stability, in the chemical industrial process that generates nitrous oxide as a byproduct. [ABSTRACT FROM AUTHOR]

Background and Aims: The agriculture sector is a major producer of greenhouse gases. To successfully transition to a green economy, we should further optimise agriculture practices so that we offset emissions while preserving crop productivity. We questioned here how two common organic management practices, reducing irrigation and conservation tillage as well as their interaction modify N2O emissions. Methods: We synthesized across 265 studies and combined a series of linear models and a meta-analytical method of moments to analyze our data. Results: We observed that reducing irrigation induced increases of about 66.1% in N2O emissions in rice but declines of over 17% for other crops, subject to mean annual temperature conditions. No tillage lowered N2O emissions, which was not the case for the reduced tillage practice. This resulted into the overall effect of conservation tillage practices on N2O emissions being non-significant. Conclusion: We present evidence that managing N2O emissions from agroecosystems depends strongly on climatic conditions and crop type used. Mapping those dependencies facilitates budgeting greenhouse gas emissions from agroecosystems and smooths the path towards meeting sustainability targets in agriculture and horticulture. [ABSTRACT FROM AUTHOR]

Rural drainage ditches serve as important sinks for heavy metals and antibiotics. However, the combined effects of heavy metals and antibiotics on ecological processes and functions in ditches remain unclear. We studied the combined effects of cadmium and doxycycline on nitrification, denitrification, anaerobic ammonia oxidation, and nitrous oxide emission rates in constructed ditch wetlands during 84 days. Results show that combined pollution decreased denitrification and anaerobic ammonia oxidation rates, but increased nitrous oxide production rates. The addition of either cadmium or doxycycline decreased the glucokinase and glyceraldehyde-3-phosphate dehydrogenase activities, and their combined pollution had a higher impact on adenosine triphosphate than on nicotinamide adenine dinucleotide. Moreover, the activities of the electron transport system, nitrate reductase, and nitrite reductase were enhanced by short-term pollutant exposure, but inhibited by long-term pollutant exposure. Structural equation modelling further revealed that electron production and transport impacted the rates of denitrification, anaerobic ammonia oxidation, and nitrous oxide production directly and indirectly by changing the activities of nitrate and nitrite reductases. [ABSTRACT FROM AUTHOR]

Background: Recreational nitrous oxide (N2O) use has become more widespread worldwide, leading to an increase in myelopathies and peripheral neuropathies. The aim of this study was to describe clinical and socioeconomical characteristics of severe N2O-induced (NI) neurological disorders (NI-NDs), to determine its incidence in the Greater Paris area and to compare it with that of similar inflammatory neurological disorders. Methods: We performed a retrospective multicentric cohort study of all adult patients with severe NI-NDs in the neurology and general internal medicine departments of the Greater Paris area from 2018 to 2021. The incidence was compared with that of non-NI-myelitis and Guillain–Barré syndrome (GBS) using a sample of 91,000 hospitalized patients sourced from health insurance data. Results: Among 181 patients, 25% had myelopathy, 37% had peripheral neuropathy and 38% had mixed disease. Most were aged between 20 and 25 years, lived in socially disadvantaged urban areas, and exhibited high rates of unemployment (37%). The incidence of NI-NDs increased during 2020 and reached a peak mid-2021. The 2021 incidence in 20–25-year-olds was 6.15 [4.72; 8.24] per 100,000 persons for NI-myelopathy and 7.48 [5.59; 9.37] for NI-peripheral neuropathy. This was significantly higher than for non-NI-myelitis (0.35 [0.02; 2.00]) and GBS (2.47 [0.64; 4.30]). The incidence of NI-NDs was two to three times higher in the most socially disadvantaged areas. Conclusion: The recent increase in recreational N2O use has led to a rise in the incidence of severe NI-NDs, particularly in young adults with low socioeconomic status for whom NI-NDs strongly outweigh similar neurological disorders. [ABSTRACT FROM AUTHOR]

Purpose: This paper reports a life cycle impact assessment (LCIA) to calculate the environmental footprint of a dental appointment using N2O, comparing single-use equipment with reusable equipment. Nitrous oxide (N2O) is used successfully in dentistry to provide sedation and pain relief to anxious patients, most commonly in children. However, N2O is a powerful climate pollutant 298 times more damaging than carbon dioxide over a 100-year estimate. Methods: The functional unit chosen for this LCIA was 30 min delivery of N2O to oxygen in a 50:50 ratio at 6 L per minute flow rate as inhalation sedation to one patient. Two types of equipment were compared to deliver the anaesthetic gas: reusable and disposable items. Results: The use of disposable equipment for N2O sedation produces a significantly larger environmental impact across nearly all of the environmental impact scores, but the overall global warming potential is comparable for both types of equipment due to the vast environmental pollution from N2O itself. Conclusion: N2O sedation is a reliable treatment adjunct but contributes to climate change. Single-use equipment has a further deleterious effect on the environment, though this is small compared to the overall impact of N2O. Dental priorities should be to deliver safe and effective care to patients that protects staff, minimises waste and mitigates impact on the environment alongside promoting research into alternatives. [ABSTRACT FROM AUTHOR]

Technologies have been developed for the in-situ treatment of urine patches deposited by grazing livestock to mitigate nitrogen (N) losses using N transformation inhibitors. For this mitigation to be effective, close contact between the applied inhibitors and the N in the urine patch is required (similar to N-fertilisers coated with inhibitors). This research aimed to determine the proportions of urine-N that mixed with inhibitor at or exceeding the threshold concentration (inhibitor concentration at which the nitrification rate is reduced by at least 40%) when inhibitors were applied to simulated urine patches at 4, 24 and 48 h after synthetic urine application. Three commonly used nitrification inhibitors (NIs) [dicyandiamide (DCD), 3,4-dimethylpyrazole phosphate (DMPP), and 2-chloro-6-(trichloromethyl) pyridine (nitrapyrin)] were applied at 40 mL of inhibitor per urine-patch at two different concentrations. The field studies were undertaken in two dairy-grazed pasture soils with contrasting drainage. Large proportions of applied NIs (38%–59% DCD, 27%–58% DMPP, and 31%–58% nitrapyrin) were retained in the pasture canopy. In most cases, the inhibitor threshold concentration was present only within the top 0–20 mm of the soil, with only 16%–40% of the urine-N present. In some cases, the proportions of urine-N intercepted was 12%–15% higher when inhibitors were applied 4 h after urine application compared to delayed application of 24 and 48 h after urine application. Our results revealed that a substantial proportion of N in the urine-patch remained out of the reach of the inhibitor solution. This is possibly due to the small volume (40 mL per 2 L urine patch, 1:50) of the inhibitors applied, with up to 59% of inhibitor solution retained in the pasture canopy. The time delays (4 to 48 h) between the urine deposition and the inhibitor application could have also contributed to this poor physical mixing between inhibitor and urine. Increasing the volume of water applied with the inhibitor and assessing the effect of rainfall/irrigation on increasing urine-N and inhibitor mixing warrants further consideration. [ABSTRACT FROM AUTHOR]

Conventional fertiliser nitrogen (N) inputs to sugarcane farming promote gaseous losses of the greenhouse gas nitrous oxide (N2O). This study investigated the effects of a nitrification inhibitor coated urea (NICU) and a 50:50 blend (N wt%) of polymer coated urea and conventional urea (PCU + U), both at a sub-recommended rate (112 kg N ha−1), on N2O emissions and productivity in a sugarcane crop. Three rates of conventional urea (70%, 100% and 130% of the recommended rate at 160 kg N ha−1) were also assessed. Nitrous oxide emissions were measured over a 7.5-month sugarcane crop using automatic chambers. High N2O emissions (> 50 g N2O–N ha−1 d−1) occurred in the first 2 months after fertiliser application, and the variability in daily emissions was best described by a combination of pH, soil nitrate concentration, soil temperature, water filled pore space and soil ammonium concentration. The blended PCU + U resulted in 62% higher, but non-significant, net fertiliser-induced N2O emissions, while NICU significantly reduced net emissions by 81%, compared to conventional urea at the same rate (112 kg N ha−1). Net emissions from conventional urea increased linearly with increasing rate, with a mean emission factor of 2.6%. Thus, applying NICU at 70% of the recommended rate achieved the greatest N2O emission reduction compared to a PCU + U blend or conventional urea at the same N rate. There was no significant reduction in yield when the fertiliser N rate was reduced to 70%. Further field trials are required to ascertain whether the use of reduced N rates and/or enhanced efficiency fertilisers can mitigate N2O emissions while maintaining or increasing productivity in the long term. [ABSTRACT FROM AUTHOR]

Purpose: Agroforestry biowaste compiles large amount of solid waste, which could be pyrolyzed into biochar and applied as soil amendment. The application of biochar has emerged as an excellent tool to mitigated the greenhouse gases emissions. However, effects of biochar could be varied according to soil type, feedstock type and rate of biochar application. Materials and methods: We studied the effect of three types of biochar (FS, fruit shell of Camellia oleifera-based; MS, spent mushroom substrate-based and RS, rice straw-based) on N2O emissions with nitrogen treatment N (urea, 0 and 0.02%) from and two soils with different origin (rice paddy soil, RPS and C. oleifera plantation soil, CPS). Results and discussion: FS and MS biochar significantly reduced N2O emissions in fertilized CPS by 66% and 33%, respectively, while that in RPS were increased by 74% and 49%, respectively. After RS biochar addition, N2O emissions were decreased by 82% only in fertilized CPS, indicating that FS and MS biochar applied in soil with the same origin as those of biochar feedstocks efficiently mitigated N2O emission rates. The relatively lower soil pH in CPS increased profoundly relative to RPS after biochar was added which contributed substantially to N2O emissions reduction, that result could be supported by the increased abundance of nosZ in RPS with nitrogen and biochar. Simultaneously, the higher soluble C and N of MS and FS biochar could increase that of RPS after application, which could further enhance N2O emissions in RPS. Conclusions: Biochar mitigated more N2O in soils with the same origin as that of biochar feedstocks compared with that of different origin ecosystems. Mitigating N2O emissions should consider the origin ecosystem of both biochar feedstock and soils, both of which profoundly impact the outcome of soil N2O mitigations. [ABSTRACT FROM AUTHOR]

For many decades, acid deposition used to pose a significant regional air pollution challenge in China. After substantial emission control of anthropogenically derived sulfur and nitrogen containing gasses, both sulfur and nitrogen deposition, as well as the acid rain-affected area, have significantly decreased compared to their peak levels. Forests, particularly in the humid subtropics, are sensitive to acid deposition, as evidenced by soil acidification, sulfate and nitrate leaching in stream water, and elevated soil nitrous oxide emission. Reduction in the total deposition of sulfur and nitrogen, caused a significant decline in sulfate and nitrate leaching from subtropical forest and subsequently in sulfate and nitrate concentrations in stream water, although there was about a 5-year delay. This delay may be attributed to the desorption of accumulated sulfate and continued elevated mineralization of accumulated nitrogen pools. Emissions of nitrous oxide, a potent greenhouse gas, also declined in nitrogen-saturated subtropical forest soils, as soil water nitrate concentration decreased. Therefore, subtropical forests in China suffering from elevated acid deposition have begun to recover. Yet, the current levels of sulfur and nitrogen deposition continue to exceed the critical loads, i.e., the assigned threshold levels in accordance with emission control policies, in more than 10% of the country’s land area, respectively, indicating remaining risks of acidification and eutrophication. Thus, further emission reductions are urgently needed, also because they will help achieving goals related to air quality and nitrous oxide emissions. [ABSTRACT FROM AUTHOR]

Global riverine nitrous oxide (N2O) emissions have increased more than 4-fold in the last century. It has been estimated that the hyporheic zones in small streams alone may contribute approximately 85% of these N2O emissions. However, the mechanisms and pathways controlling hyporheic N2O production in stream ecosystems remain unknown. Here, we report that ammonia-derived pathways, rather than the nitrate-derived pathways, are the dominant hyporheic N2O sources (69.6 ± 2.1%) in agricultural streams around the world. The N2O fluxes are mainly in positive correlation with ammonia. The potential N2O metabolic pathways of metagenome-assembled genomes (MAGs) provides evidence that nitrifying bacteria contain greater abundances of N2O production-related genes than denitrifying bacteria. Taken together, this study highlights the importance of mitigating agriculturally derived ammonium in low-order agricultural streams in controlling N2O emissions. Global models of riverine ecosystems need to better represent ammonia-derived pathways for accurately estimating and predicting riverine N2O emissions. NH4+-derived pathways, rather than NO3--derived pathway, are the dominant hyporheic N2O sources in lower-order streams. These findings provide insights into better estimation of N2O emissions in global models of riverine ecosystems and emphasize the importance of managing ammonium. [ABSTRACT FROM AUTHOR]

Background: Nitrous oxide (N2O) has been in industrial and recreational use since the 18th century and is commonly perceived as a safe substance. Despite its increasing uptake, there is a lack of data on N2O-related harm. This article explores the misuse of N2O associated with various complications, with a focus on frostbite as a novel phenomenon. We aimed to review the existing body of literature and describe the epidemiology, presentation, pathophysiology, and management of patients with N2O-related frostbite injuries in the upper aerodigestive tract. Methods: A literature search was conducted across PubMed, MEDLINE and Embase databases, focusing on English language articles related to N2O use patterns, associated injuries, pathophysiology, investigations, and management. Results: The search yielded 122 results, of which fifteen case reports and case series were included in the study. There are 54 total cases included in the analysis. There is an equal distribution of males and females among a young population with a median age of 27.5 years. Presentations of skin and mucosal injuries across different anatomical sites as well as their management approaches are described. Conclusions: The pathophysiology of frostbite involves both direct and indirect effects, leading to tissue ischaemia, inflammation, and immune responses. Complications, including airway obstruction, underscore the severity of N2O-related injuries. Management strategies include securing the airway, surgical debridement, and pharmacological interventions such as prophylactic corticosteroids and antibiotics. N2O is a documented causative agent of frostbite injuries. Awareness of its rising prevalence and potential complications is key in the treatment of patients with complications sustained from the use of N2O. Level of evidence: Not ratable [ABSTRACT FROM AUTHOR]

Aerobic methanotrophic bacteria are considered strict aerobes but are often highly abundant in hypoxic and even anoxic environments. Despite possessing denitrification genes, it remains to be verified whether denitrification contributes to their growth. Here, we show that acidophilic methanotrophs can respire nitrous oxide (N2O) and grow anaerobically on diverse non-methane substrates, including methanol, C-C substrates, and hydrogen. We study two strains that possess N2O reductase genes: Methylocella tundrae T4 and Methylacidiphilum caldifontis IT6. We show that N2O respiration supports growth of Methylacidiphilum caldifontis at an extremely acidic pH of 2.0, exceeding the known physiological pH limits for microbial N2O consumption. Methylocella tundrae simultaneously consumes N2O and CH4 in suboxic conditions, indicating robustness of its N2O reductase activity in the presence of O2. Furthermore, in O2-limiting conditions, the amount of CH4 oxidized per O2 reduced increases when N2O is added, indicating that Methylocella tundrae can direct more O2 towards methane monooxygenase. Thus, our results demonstrate that some methanotrophs can respire N2O independently or simultaneously with O2, which may facilitate their growth and survival in dynamic environments. Such metabolic capability enables these bacteria to simultaneously reduce the release of the key greenhouse gases CO2, CH4, and N2O. Aerobic methanotrophic bacteria are considered strict aerobes but are often highly abundant in hypoxic or anoxic environments. Here, the authors show that acidophilic methanotrophs can respire nitrous oxide and grow anaerobically on diverse non-methane substrates, including methanol, C-C substrates, and hydrogen. [ABSTRACT FROM AUTHOR]

Aim: Incorporating non-bloat legumes into grass pastures can reduce enteric methane and alter cattle urinary urea N output by increasing protein intake. Deposition of high urea N urine influences soil N-cycling microbes and potentially N2O production. We studied how urine urea N concentration affects soil nitrifier and denitrifier abundances, activities, and N2O production. Methods: 15N13C-labelled urea dissolved in cattle urine was added at 3.5 and 7.0 g L−1 to soils from a grazed, non-bloat legume pasture and incubated under controlled conditions. CO2, N2O, 13C-CO2, and 15N-N2O production were quantified over 240 h, along with nitrifier and denitrifier N-cycling genes and mRNA transcripts. Results: High urea urine increased total N2O relative to the control; low urea was not significantly different from the control or the high urea treatment. As a result, N2O-N emission factors were not significantly different between the low urea treatment (1.17%) and high urea treatment (0.94%). Doubling urea concentration doubled CO2-Curea and N2O-Nurea but not total N2O-N. Urine addition initially inhibited then increased AOB transcripts and gene abundances. nirK and nirS transcript abundances indicated that denitrification by ammonia oxidizers and/or heterotrophic denitrifiers dominated N2O production. Urine addition increased nosZ-II vs. nosZ-I transcripts, improving soil N2O reduction potential. Conclusion: Characterizing this interplay between nitrifiers and denitrifiers improves the understanding of urine patch N2O sinks and source dynamics. This mechanistic information helps to explain the constrained short-term N2O emissions observed in response to excess urine N excretion from cattle consuming high protein diets, e.g. non-bloat legumes. [ABSTRACT FROM AUTHOR]

Climate change-related warming and increased precipitation may alter winter snow cover and thawing events, and therefore, may carry significant consequences for nitrous oxide (N2O) production pathways such as denitrification, and the abundance and expression of denitrifying microorganisms. We used a soil microcosm study to investigate the combined effect of soil thaw temperature, initial water filled pore space (WFPS) prior to soil freezing, and snowmelt infiltration simulated by the addition of water on N2O emission and denitrification rates, soil respiration rate, and the abundance and transcription of denitrifying (nirK, nirS, and nosZ) bacteria during a single freeze-thaw event. Soil respiration rate was primarily controlled by an increase in soil thaw temperature, whereas soil N2O emission and denitrification rates were generally greater in soils with a higher initial WFPS and soil thaw temperature. In contrast, snowmelt infiltration generally had a negligible effect on these rates, which may be related to pre-existing soil conditions that were already conducive to denitrification. Unexpectedly, the nosZ transcript/nosZ gene abundance ratio was lower in soils thawed at 8.0 °C compared to 1.5 °C; however, this may have resulted in a lower N2O reduction, thus explaining the greater levels of N2O emitted from soils thawed at 8.0 °C. Overall, this study demonstrated that increased N2O production during a single freeze-thaw event was primarily linked to antecedent conditions of high initial WFPS, soil thaw temperature, and a synergistic interplay between these two environmental parameters, and provides evidence that an increase in annual temperature and precipitation, along with the timing of precipitation, may further stimulate N2O production pathways. [ABSTRACT FROM AUTHOR]

Understanding the bacteria associated with nitrification and denitrification is crucial for comprehending the processes that lead to nitrous oxide emissions in agricultural greenhouse soils. Therefore, it is important to determine their abundance and expression to gain insight into these processes. The aim of this study was to explore the bacterial communities associated with denitrification in a greenhouse agricultural soil amended with crop residues and manure for six years. For this purpose, we proceeded to detect and quantify the genes nirK and nirS and the gene nosZ through clone library construction, sequencing, phylogenetic analysis, and quantitative polymerase chain reaction (qPCR). Sequence analysis based on the clone library revealed that many of the nirS or nirK genes detected were not closely related to known denitrifier bacteria, but some of the nosZ sequences were related to the genera such as Pseudomonas, Halomonas, and Marinobacter. Furthermore, the qPCR revealed a high abundance of DNA copies in nirK, 6.08 × 109 ± 1.16 × 109, while nirS and nosZ showed lower values, 9.05 × 106 ± 1.65 × 106 and 8.71 × 106 ± 1.44 × 106, respectively. However, the highest expression rate was observed for nirS (mRNA/DNA ratio = 3.10 × 10− 3), while nirK and nosZ showed 10-fold lower expression rates (4.4 × 10− 4 and 3.5 × 10− 4, respectively). The results of this work provide a preliminary overview of the diversity, abundance and expression of key genes associated with the denitrification process in this type of soil and are a starting point for further studies to understand how this type of soil management can influence the denitrification process. [ABSTRACT FROM AUTHOR]

Nitrous oxide (N2O) generation during composting not only leads to losses of nitrogen (N) but also reduces the agronomic values and environmental benefits of composting. This study aimed to investigate the effect of the C/N ratio on N2O emissions and its underlying mechanisms at the genetic level during the composting of vegetable waste. The experiment was set up with three treatments, including low C/N treatment (LT, C/N = 18), middle C/N treatment (MT, C/N = 30), and high C/N treatment (HT, C/N = 50). The results showed that N2O emission was mainly concentrated in the cooling and maturation periods, and the cumulative N2O emissions decreased as the C/N ratio increased. Specifically, the cumulative N2O emission was 57,401 mg in LT, significantly higher than 2155 mg in MT and 1353 mg in HT. Lowering the C/N ratio led to increasing TN, NH4+-N, and NO3−-N contents throughout the composting process. All detected nitrification-related gene abundances in LT continued to increase during composting, significantly surpassing those in MT during the cooling period. By contrast, in HT, there was a slight increase in the abundance of detected nitrification-related genes but a significant decrease in the abundance of narG, napA, and norB genes in the thermophilic and cooling periods. The structural equation model revealed that hao and nosZ genes were vital in N2O emissions. In conclusion, increasing the C/N ratio effectively contributed to N2O reduction during vegetable waste composting. [ABSTRACT FROM AUTHOR]

Cover cropping is a promising strategy to improve soil health, but it may also trigger greenhouse gas emissions, especially nitrous oxide (N2O). Beyond nitrogen (N) availability, cover crop residue decomposition may accelerate heterotrophic respiration to limit soil O2 availability, hence promote N2O emissions from denitrification under sub-optimal water-filled pore space (WFPS) conditions that are typically not conducive to large N2O production. We conducted a 21-day incubation experiment to examine the effects of contrasting cover crop residue (grass vs legume) decomposition on soil O2 and biogeochemical changes to influence N2O and CO2 emissions from 15N labeled fertilized soils under 50% and 80% WFPS levels. Irrespective of cover crop type, mixing cover crop residue with N fertilizer resulted in high cumulative N2O emissions under both WFPS conditions. In the absence of cover crop residues, the N fertilizer effect of N2O was only realized under 80% WFPS, whereas it was comparable to the control under 50% WFPS. The N2O peaks under 50% WFPS coincided with soil O2 depletion and concomitant high CO2 emissions when cover crop residues were mixed with N fertilizer. While N fertilizer largely contributed to the total N2O emissions from the cover crop treatments, soil organic matter and/or cover crop residue derived N2O had a greater contribution under 50% than 80% WFPS. Our results underscore the importance of N2O emissions from cover crop-based fertilized systems under relatively lower WFPS via a mechanism of respiration-induced anoxia and highlight potential risks of underestimating N2O emissions under sole reliance on WFPS. [ABSTRACT FROM AUTHOR]

Copper-containing nitrous oxide reductase catalyzes a 2-electron reduction of the green-house gas N2O to yield N2. It contains two metal centers, the binuclear electron transfer site CuA, and the unique, tetranuclear CuZ center that is the site of substrate binding. Different forms of the enzyme were described previously, representing variations in oxidation state and composition of the metal sites. Hypothesizing that many reported discrepancies in the structural data may be due to radiation damage during data collection, we determined the structure of anoxically isolated Marinobacter nauticus N2OR from diffraction data obtained with low-intensity X-rays from an in-house rotating anode generator and an image plate detector. The data set was of exceptional quality and yielded a structure at 1.5 Å resolution in a new crystal form. The CuA site of the enzyme shows two distinct conformations with potential relevance for intramolecular electron transfer, and the CuZ cluster is present in a [4Cu:2S] configuration. In addition, the structure contains three additional types of ions, and an analysis of anomalous scattering contributions confirms them to be Ca2+, K+, and Cl–. The uniformity of the present structure supports the hypothesis that many earlier analyses showed inhomogeneities due to radiation effects. Adding to the earlier description of the same enzyme with a [4Cu:S] CuZ site, a mechanistic model is presented, with a structurally flexible CuZ center that does not require the complete dissociation of a sulfide prior to N2O binding. The [4Cu:2S] CuZ site in M. nauticus N 2O reductase. The electron density map shown is contoured at the 5 σ level, highlighting the presence of two sulfide ligands. 705x677mm (72 x 72 DPI) [ABSTRACT FROM AUTHOR]

Surface drip fertigation has demonstrated promising results regarding the mitigation of nitrous oxide (N2O) emissions. The use of subsurface irrigation may offer the possibility of reducing these emissions further due to the modification of the soil moisture profile and N allocation, both of which affect the biochemical processes leading to N2O fluxes. However, the mitigation potential of subsurface irrigation combined with different mineral nitrogen (N) fertilizers (ammonium or nitrate-based, use of nitrification inhibitors) still needs to be evaluated. To respond to this need, a 2-year field experiment was set up in central Spain to test two different drip-fertigation systems (surface and subsurface at 30 cm depth) and four N fertilization treatments (control, calcium nitrate, and ammonium sulfate with or without the nitrification inhibitor 3,4-dimethylpyrazole phosphate, DMPP) in an irrigated maize (Zea mays L.) crop. Nitrous oxide emissions, mineral N concentrations (ammonium, NH4+, and nitrate, NO3−), and abundance of key N genes involved in nitrification and denitrification processes were measured in two soil layers (0–20 and 20–40 cm). Regardless of the irrigation system, ammonium sulfate gave the highest cumulative N2O losses in both campaigns, while calcium nitrate and the use of DMPP were the most effective strategies to abate N2O fluxes in the first and second years, respectively. Differences between irrigation systems were not statistically significant for cumulative N2O emissions, despite the clear effect on topsoil mineral N (higher NH4+ and NO3− concentrations in surface and subsurface drip, respectively). Nitrous oxide emissions were positively correlated with soil NH4+ concentrations. Gene abundances were not a trustworthy predictor of N2O losses in the 1st year, although a clear inhibitory effect of fertilization on microbial communities (i.e., ammonia oxidizers, nitrite reducers, and N2O reducers) was observed during this campaign. During the second year, nitrifying and denitrifying genes were affected by irrigation (with higher abundances in the 20–40 cm layer in subsurface than in surface drip) and by the addition of DMPP (which had a detrimental effect on gene abundances in both irrigation systems that disappeared after the fertigation period). In conclusion, the use of DMPP or calcium nitrate instead of ammonium sulfate may enhance the chances for an additional mitigation in both surface and subsurface irrigation systems. [ABSTRACT FROM AUTHOR]

Drained agricultural peatlands occupy only 1% of agricultural land but are estimated to be responsible for approximately one third of global cropland greenhouse gas emissions. However, recent studies show that greenhouse gases fluxes from agricultural peatlands can vary by orders of magnitude over time. The relationship between these hot moments (individual fluxes with disproportionate impact on annual budgets) of greenhouse gas emissions and individual chamber locations (i.e. hot spots with disproportionate observations of hot moments) is poorly understood, but may help elucidate patterns and drivers of high greenhouse gas emissions from agricultural peatland soils. We used continuous chamber-based flux measurements across three land uses (corn, alfalfa, and pasture) to quantify the spatiotemporal patterns of soil greenhouse gas emissions from temperate agricultural peatlands in the Sacramento-San Joaquin Delta of California. We found that the location of hot spots of emissions varied over time and were not consistent across annual timescales. Hot moments of nitrous oxide (N2O) and carbon dioxide (CO2) fluxes were more evenly distributed across space than methane (CH4). In the corn system, hot moments of CH4 flux were often isolated to a single location but locations were not consistent across years. Spatiotemporal variability in soil moisture, soil oxygen, and temperature helped explain patterns in N2O fluxes in the annual corn agroecosystem but were less informative for perennial alfalfa N2O fluxes or CH4 fluxes across ecosystems, potentially due to insufficient spatiotemporal resolution of the associated drivers. Overall, our results do not support the concept of persistent hot spots of soil CO2, CH4, and N2O emissions in these drained agricultural peatlands. Hot moments of high flux events generally varied in space and time and thus required high sample densities. Our results highlight the importance of constraining hot moments and their controls to better quantify ecosystem greenhouse gas budgets. [ABSTRACT FROM AUTHOR]

The greenhouse gas (GHG) emissions of spring cereal monoculture under long-term conventional tillage (CT) and no-till (NT) treatment established in 2018 were measured in a peatland in Southwestern Finland during the period 2018–2021. Nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) fluxes were measured with chambers approximately every two weeks throughout the period under study. Net ecosystem exchange was measured during the growing seasons, and hourly ecosystem respiration (ER) and gross photosynthesis (GP) were modelled with empirical models. Across the whole period, annual emissions were 6.8 ± 1.2 and 5.7 ± 1.2 Mg CO2–C ha −1 yr−1 (net ecosystem carbon balance), 8.8 ± 2.0 and 7.1 ± 2.0 kg N2O–N ha−1 yr−1, and − 0.43 ± 0.31 and − 0.40 ± 0.31 kg CH4-C ha−1 yr−1 for CT and NT, respectively. The global warming potential was lower in NT (p = 0.045), and it ranged from 26 to 34 Mg CO2 eq. ha−1 yr−1 in CT and from 19 to 31 Mg CO2 eq. ha−1 yr−1 in NT. The management effect on the rates of single GHGs was not consistent over the years. Higher GP was found in CT in 2019 and in NT in 2020. Differences in ER between treatments occurred mostly outside the growing season, especially after ploughing, but the annual rates did not differ statistically. NT reduced the N2O emissions by 31% compared to CT in 2020 (p = 0.044) while there were no differences between the treatments in other years. The results indicate that NT may have potential to reduce slightly CO2 and N2O emissions from cultivated peat soil, but the results originate from the first three years after a management change from CT to NT, and there is still a lack of long-term results on NT on cultivated peat soils. [ABSTRACT FROM AUTHOR]

Peatlands play a crucial role in the global carbon (C) cycle, making their restoration a key strategy for mitigating greenhouse gas (GHG) emissions and retaining C. This study analyses the most common restoration pathways employed in boreal and temperate peatlands, potentially applicable in tropical peat swamp forests. Our analysis focuses on the GHG emissions and C retention potential of the restoration measures. To assess the C stock change in restored (rewetted) peatlands and afforested peatlands with continuous drainage, we adopt a conceptual approach that considers short-term C capture (GHG exchange between the atmosphere and the peatland ecosystem) and long-term C sequestration in peat. The primary criterion of our conceptual model is the capacity of restoration measures to capture C and reduce GHG emissions. Our findings indicate that carbon dioxide (CO2) is the most influential part of long-term climate impact of restored peatlands, whereas moderate methane (CH4) emissions and low N2O fluxes are relatively unimportant. However, lateral losses of dissolved and particulate C in water can account up to a half of the total C stock change. Among the restored peatland types, Sphagnum paludiculture showed the highest CO2 capture, followed by shallow lakes and reed/grass paludiculture. Shallow lakeshore vegetation in restored peatlands can reduce CO2 emissions and sequester C but still emit CH4, particularly during the first 20 years after restoration. Our conceptual modelling approach reveals that over a 300-year period, under stable climate conditions, drained bog forests can lose up to 50% of initial C content. In managed (regularly harvested) and continuously drained peatland forests, C accumulation in biomass and litter input does not compensate C losses from peat. In contrast, rewetted unmanaged peatland forests are turning into a persistent C sink. The modelling results emphasized the importance of long-term C balance analysis which considers soil C accumulation, moving beyond the short-term C cycling between vegetation and the atmosphere. [ABSTRACT FROM AUTHOR]

Despite the documented increase in greenhouse gas (GHG) emissions from Southeast Asian peat swamp forest degradation and conversion to oil palm over recent decades, reliable estimates of emissions of nitrous oxide (N2O) and methane (CH4) are lacking. We measured soil fluxes of N2O and CH4 and their environmental controls along a peatland transition from primary forest (PF) to degraded drained forest (DF) to oil palm plantation (OP) over 18 months in Jambi, Sumatra, Indonesia. Sampling was conducted monthly at all sites and more intensively following two fertilization events in the OP. Mean annual emissions of N2O (kg N ha−1 yr−1) were 1.7 ± 0.2 for the PF, 2.3 ± 0.2 for the DF and for the OP 8.1 ± 0.8 without drainage canals (DC) and 7.7 ± 0.7 including DC. High N2O emissions in the OP were driven by peat decomposition, not by N fertilizer addition. Mean CH4 annual fluxes (kg C ha−1 yr−1) were 8.2 ± 1.9 for the PF, 1.9 ± 0.4 for the DF, and 1.6 ± 0.3 for the OP with DC and 1.1 ± 0.2 without. Considering their 20-year global warming potentials (GWP), the combined non-CO2 GHG emission (Mg CO2-equivalent ha−1 yr−1) was 3.3 ± 0.6 for the PF and 1.6 ± 0.2 for the DF. The emission in the OP (3.8 ± 0.3 with or without DC) was similar to the PF because reductions in CH4 emissions offset N2O increases. However, considering 100-year GWP, the combined non-CO2 GHG emission was larger in the OP (3.4 ± 0.3 with DC and 3.5 ± 0.3 without) compared to both the PF and the DF (1.5 ± 0.2 and 1.2 ± 0.1, respectively). The increase in peat N2O emissions associated with the land-use change transition from primary forest to oil palm plantation at our sites provides further evidence of the urgent need to protect tropical peat swamp forests from drainage and conversion. [ABSTRACT FROM AUTHOR]

Greenhouse gas (GHGs) emissions from peatlands contribute significantly to ongoing climate change because of human land use. To develop reliable and comprehensive estimates and predictions of GHG emissions from peatlands, it is necessary to have GHG observations, including carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), that cover different peatland types globally. We synthesize published peatland studies with field GHG flux measurements to identify gaps in observations and suggest directions for future research. Although GHG flux measurements have been conducted at numerous sites globally, substantial gaps remain in current observations, encompassing various peatland types, regions and GHGs. Generally, there is a pressing need for additional GHG observations in Africa, Latin America and the Caribbean regions. Despite widespread measurements of CO2 and CH4, studies quantifying N2O emissions from peatlands are scarce, particularly in natural ecosystems. To expand the global coverage of peatland data, it is crucial to conduct more eddy covariance observations for long-term monitoring. Automated chambers are preferable for plot-scale observations to produce high temporal resolution data; however, traditional field campaigns with manual chamber measurements remain necessary, particularly in remote areas. To ensure that the data can be further used for modeling purposes, we suggest that chamber campaigns should be conducted at least monthly for a minimum duration of one year with no fewer than three replicates and measure key environmental variables. In addition, further studies are needed in restored peatlands, focusing on identifying the most effective restoration approaches for different ecosystem types, conditions, climates, and land use histories. [ABSTRACT FROM AUTHOR]

Catalysts based on high-silica zeolites with Si/Al ratios of 50 and 80 (ZSM-5-50 and ZSM-5-80) modified by Ca, Sr, Cr, Mn, and Sb ions are synthesized and studied in the reaction of the oxidation of benzene to phenol by nitrous oxide. It is shown that catalysts containing about 0.1–0.2 wt % of Sb ions are more active and selective in the reaction of the direct oxidation of benzene to phenol by nitrous oxide. It formally corresponds to the substitution of 1/12 and 1/6 ions of H ions by Sb ions in a ratio of 1 : 1 of the zeolite. In the presence of a sample composed of ZSM-5-50 + 1/12 Sb at a temperature of 450°C and a contact time of 1 s, a phenol yield of 61.2% is achieved with a selectivity of 96%, which is approximately twice as high as the values known in the literature for other for other Me-ZSM-5 catalysts. At the same time, the sample with the composition of ZSM-5-50 + 1/6Sb turns out to be more stable than the other catalysts based on ZSM-5 zeolites. A model is also proposed for the activation of nitrous oxide on single active sites (located at a sufficient distance from each other) of the catalyst, which explains the higher efficiency of nitrous oxide as oxidant than that of molecular oxygen in the reaction of the direct oxidation of benzene to phenol in the presence of Me-ZSM-5 catalysts with a low concentration (less than 0.1%) of Me ions. [ABSTRACT FROM AUTHOR]

Constructed wetlands (CWs) are widely used to treat secondary effluent. However, simultaneously removing ammonia (NH4+-N) and nitrate (NO3−–N) is challenging because of insufficient oxygen and carbon sources. In this study, a novel composite material (MPCM) comprising MnO2 and polycaprolactone was developed as a substrate for CWs to enhance the synchronous removal of NH4+–N and NO3−–N. The CWs with a higher MPCM content (H-CW), lower MPCM content (L-CW), and controlled CW (C-CW) exhibited average NH4+–N removal efficiencies of 75.69%, 70.49%, and 52.40%, respectively. The 15N isotope tracking technique showed that NH4+–N removal was attributed to anaerobic ammonia oxidation mediated by MnO2 reduction (Mnammox), which accounted for 17.16%–27.24% of the NH4+–N removal in the composite material layers (0–20 cm) of the H-CW and L-CW. The richness of ammonia oxidizers in the upper layers (40–50 cm) of the H-CW and L-CW further facilitated NH4+–N removal. Moreover, the average total nitrogen (TN) removal efficiencies of the H-CW and L-CW were 1.99 and 1.59 times that of C-CW, respectively, owing to enhanced denitrification by MPCM. Furthermore, N2O emissions were reduced by 81.31% and 70.83% in the H-CW and L-CW, respectively. This study provides an effective approach for improving nitrogen removal and reducing N2O emissions during the treatment of secondary effluent by CWs. [ABSTRACT FROM AUTHOR]

Support-vector machines (SVMs) can potentially improve patient monitoring during nitrous oxide anaesthesia. By elucidating the effects of low-dose nitrous oxide on the power spectra of multi-channel EEG recordings, we quantified the degree to which these effects generalise across participants. In this single-blind, cross-over study, 32-channel EEG was recorded from 12 healthy participants exposed to 0, 20, 30 and 40% end-tidal nitrous oxide. Features of the delta-, theta-, alpha- and beta-band power were used within a 12-fold, participant-wise cross-validation framework to train and test two SVMs: (1) binary SVM classifying EEG during 0 or 40% exposure (chance = 50%); (2) multi-class SVM classifying EEG during 0, 20, 30 or 40% exposure (chance = 25%). Both the binary (accuracy 92%) and the multi-class (accuracy 52%) SVMs classified EEG recordings at rates significantly better than chance (p < 0.001 and p = 0.01, respectively). To determine the relative importance of frequency band features for classification accuracy, we systematically removed features before re-training and re-testing the SVMs. This showed the relative importance of decreased delta power and the frontal region. SVM classification identified that the most important effects of nitrous oxide were found in the delta band in the frontal electrodes that was consistent between participants. Furthermore, support-vector classification of nitrous oxide dosage is a promising method that might be used to improve patient monitoring during nitrous oxide anaesthesia. [ABSTRACT FROM AUTHOR]

Greenhouse gas emissions have an impact on agricultural activity in the West African region, which is largely agrarian. As a result, most of the countries in the region are food insecure, and many people are malnourished. There is a lack of a multidisciplinary perspective that analyzes greenhouse gas emissions and proposes mitigation strategies to help the region contribute to reducing greenhouse gas emissions. To mitigate this challenge, this study examined the threshold beyond which agriculture will reduce greenhouse gas (measured by carbon dioxide emissions, methane emissions, and nitrous oxide emissions) in West Africa. The study used a sample of 16 West African nations from the years 2002 to 2018 and the panel threshold estimator for the data analysis. The results showed that agriculture will reduce carbon and nitrous oxide emissions beyond threshold values of 3.287 representing about $26.762 million, and 3.683 representing about $39.766 million, respectively. However, the threshold impact of agriculture on methane emissions in West Africa was insignificant. The results also demonstrated that while there is no causative association between agriculture and methane emissions, there is a unidirectional causation link between carbon emissions and agriculture and nitrous oxide emissions and agriculture, respectively. The study suggested agricultural investments in both traditional high-yielding technology and adaptation are needed to meet the development goal of climate change. [ABSTRACT FROM AUTHOR]

Global potent greenhouse gas nitrous oxide (N2O) emissions from soil are accelerating, with increases in the proportion of reactive nitrogen emitted as N2O, i.e., N2O emission factor (EF). Yet, the primary controls and underlying mechanisms of EFs remain unresolved. Based on two independent but complementary global syntheses, and three field studies determining effects of acidity on N2O EFs and soil denitrifying microorganisms, we show that soil pH predominantly controls N2O EFs and emissions by affecting the denitrifier community composition. Analysis of 5438 paired data points of N2O emission fluxes revealed a hump-shaped relationship between soil pH and EFs, with the highest EFs occurring in moderately acidic soils that favored N2O-producing over N2O-consuming microorganisms, and induced high N2O emissions. Our results illustrate that soil pH has a unimodal relationship with soil denitrifiers and EFs, and the net N2O emission depends on both the N2O/(N2O + N2) ratio and overall denitrification rate. These findings can inform strategies to predict and mitigate soil N2O emissions under future nitrogen input scenarios. Intermediate soil acidification alters the denitrifier community composition and induces high nitrous oxide (N2O) emissions, which contributes to the observed acceleration of N2O emissions from global soils [ABSTRACT FROM AUTHOR]

The study focuses on the application range of nitrous oxide as a hold-up time marker in supercritical fluid chromatography (SFC). This compound has been suggested a decade ago to be used as unretained marker, something that the field of SFC was missing for a long time, since its beneficial properties make it an ideal candidate as hold-up time marker. Determination of the hold-up volume and actual volumetric flow rates have always been problematic in SFC due to the compressibility of carbon dioxide and one part of this is the difficulty of hold-up time measurements. Depending on the mobile phase, different methods have been used to measure the hold-up time with varying results. Nitrous oxide and other molecules have been compared in different conditions, mobile phases and stationary phases. In all cases, nitrous oxide gave the lowest elution times. However, detection was difficult in mobile phases containing 10% or more of organic modifier, because most solvents mask the signal of nitrous oxide. Interestingly, the choice of stationary phase also had a slight effect on detection, while different pressure and temperature settings affected each compound in a different manner. [ABSTRACT FROM AUTHOR]

Air pollution is a danger to economies throughout the European Union. Industry, population expansion, a building boom owing to housing and infrastructure development, increasing vehicle traffic, crowded streets, a lack of availability of clean fuel, and ineffective control programs are the primary causes. Toxic air is a double-edged sword for a country's health since it affects just a tiny fraction of Europe's population. The financial burden and healthcare expenses for people rise when health expenditures rise. The present research looks at how dangerous air levels, healthcare costs, and the expansion of the European Union's economy are all connected. The findings are based on data collected over 29 years and account for the abovementioned variables. The results of the unit root test have the significant probability values of all variables: health expenditures (HE), gross domestic product (GDP), nitrous oxides (NOX), and carbon dioxides (CO2) emissions at both level and first difference. We used the Johansen, Kao, and Pedroni cointegration tests to test the null hypothesis of no cointegration to see that sample variables had a long-term association. The PMG-ARDL test was used to get these findings. The results confirmed the significant probability values of dependent variables in long- and short-run results that GDP has a positive and significant effect on health expenditure, while NOX and CO2 emissions have a negative and significant impact on (HE), in the European Union. To verify the results, we applied the robustness test, fully modified OLS (FMOLD), and dynamic OLS (DOLS); the robustness test results validated the PMG-ARDL test results. Environmental pollution (CO2, NOX) has a significant and negative impact on healthcare expenditures and a significant effect on GDP (HE) in the EU region. The findings of this research have implications for a wide range of parties, including those who would examine the link between factors in a study meant to improve air quality, distribute health resources, or develop strategies for economic development. [ABSTRACT FROM AUTHOR]

While climate change significantly influences nitrogen cycling and its related microbial diversity, the effects of warming on nitrate reduction processes and their related microbial communities and functional gene abundances in mangrove sediments are not fully understood. In this study, mangrove sediment slurry was incubated under six controlled temperatures for 28 days to simulate warming trends. Following the incubation, rates of denitrification (DNF), anaerobic ammonium oxidation (ANA), and nitrate decomposition reduction to ammonium (DNRA), and net nitrous oxide (N2O) production, functional gene abundances, and the structure of functional microbial taxa were investigated using a 15N tracer method, high-throughput sequencing, and qPCR methods. DNF's optimal temperature was 25 °C, but ANA's ranged from 25 to 35 °C. The DNRA rates; nosZ, nirS, and nrfA gene abundances; nosZ/(nirK + nirS) ratios; and, in particular, net N2O production in the mangrove sediment significantly increased with increasing temperature. Furthermore, DNRA's contributions to nitrate reduction increased from 26.70% at 10 °C to 44.42% at 40 °C, suggesting that the DNRA process transforms more nitrate to ammonia and retains more nitrogen within mangrove sediments than the other processes do. Meanwhile, microbial taxa changed significantly in relation to DNRA, indicating that DNRA is enhanced as temperature increases. Also, temperature explained most of the variance in the dominant bacterial communities (68.3%), nitrate reduction functional genes (91.8%), and process rates (79.9%). Thus, warming promotes nitrogen conservation in mangrove sediments but stimulates N2O emissions, which in turn exacerbates global warming. [ABSTRACT FROM AUTHOR]

Background: The recreational use of nitrous oxide (N2O) has gained popularity over recent years. We present a case series of excessive N2O users with neurological complications. Methods: In this retrospective three-centre study, we used a text mining algorithm to search for patients who used N2O recreationally and visited a neurologist. Results: We identified 251 patients. The median duration of N2O use was 11 months (interquartile range [IQR], 3–24) and the median amount of N2O used per occasion 1.6 kg (IQR 0.5–4.0). Clinically, polyneuropathy (78%), myelopathy (41%), and encephalopathy (14%) were the most common diagnoses. An absolute vitamin B12 deficiency of < 150 pmol/L was found in 40% of cases. In 90%, at least one indicator of functional vitamin B12 status (vitamin B12, homocysteine, or methylmalonic acid) was abnormal. MRI showed signs of myelopathy in 30/55 (55%) of cases. In 28/44 (64%) of those who underwent electromyography, evidence of axonal polyneuropathy was found. Most (83%) patients were treated with vitamin B12 supplementation, and 23% were admitted to the hospital. Only 41% had follow-up for ≥ 30 days, and 79% of those showed partial or complete recovery. Conclusions: In this case series of excessive N2O users, we describe a high prevalence of polyneuropathy, myelopathy, and encephalopathy. Stepwise testing for serum levels of vitamin B12, homocysteine, and methylmalonic acid may support the clinical diagnosis. Due to low sensitivity, MRI of the spinal cord and electromyography have limited value. Effective treatment should incorporate supplementation of vitamin B12 and strategies to prevent relapses in N2O use. [ABSTRACT FROM AUTHOR]

Nitrous oxide (N2O) is a potent greenhouse gas that accumulates in the atmosphere due to anthropogenic N2O emissions, disrupting the nitrogen balance. N2O reductase (N2OR) in denitrifying bacteria contributes to the nitrogen cycle by converting N2O to molecular nitrogen as a last step. For the reduction of N2O during denitrification, electron donors must supply two electrons. This review discusses the in vivo physiological electron donors involved in the reduction reaction of N2OR: cytochrome c55X and pseudoazurin, as well as the non-physiological electron donors commonly used in N2OR studies: reduced MV/BV, dithionite, and ascorbate. The kinetic parameters of the connection between N2OR and the electron donors are also included. This aim of this review to gain further insight into the reduction mechanism of N2OR, presenting the electron transfer center, CuA, and the catalytic center, CuZ, of N2OR. The state changes of Cu site have a significant impact on electron transfer and N2O binding. Moreover, the review focuses on potential electron transfer pathways and binding sites in the electron donor → CuA → CuZ process, along with the steady-state turnover in the CuZ site. Additionally, the review explains the commonly used methods in mechanistic studies of N2OR. Modulating the electron transfer pathways of N2OR holds promise as an approach to decreasing N2O emissions. [ABSTRACT FROM AUTHOR]