NH3 Emissions Research Articles

Reducing global food loss and waste could improve air quality and lower the risk of premature mortality

While the global food system substantially contributes to environmental degradation and climate change, significant amounts of lost or wasted foods along the food supply chain actively contribute to global air pollution and related health risks. In this study, we use an environmentally-extended input–output model to quantify air pollution embedded in global food loss and waste (FLW) and investigate how FLW reduction policies can mitigate air pollution linked to food consumption, decreasing associated premature mortality risks across global regions. While estimating a positive impact of FLW reduction policies on decreasing air pollution levels (from −1.5% of SO2 emissions to −10.2% of NH3 emissions) and mortality reductions (over 67 000 lives worldwide) our findings highlight that rebound effects, wherein a reallocation of consumption from food to non-food commodities, decrease health and environmental benefits by over three quarters (compared to the case with no rebound). Such rebound effects can be substantially mitigated when final consumption shifts towards less pollution-intensive products, such as service activities, rather than conforming to the current composition of non-food consumption. Our results suggest that FLW-related policies would benefit from complementary measures that incentivize sustainable non-food consumption to effectively foster the transition towards a healthier and more sustainable planet.

Construction and Evaluation of The Wind Tunnel Technique for Estimating Ammonia Volatilization from Land

Agriculture is mainly responsible for ammonia (NH3) volatilization. Among all agricultural activities, livestock and especially animal manures are the most important sources of NH3 emissions. Manure application which not only exacerbate greenhouse gas emissions, but also leads to eutrophication of water bodies. Many studies have shown that surface application of manure can lead to large ammonia losses and run off, on the other hand that tillage can substantially reduce these losses. It is necessary to determine ammonia flux from manure-amended soils to improve management manure handling practices for minimizing agriculture’s impact on the environment. From this point of view, one of the direct measured method was used to determine this volatilization. The objections of this work were: i) The design, construction, physical calibration, and operation of the little wind tunnels. ii) Recover ammonia loss from bovine slurry by little wind tunnel method. iii) Determine the effect of slurry application depth on ammonia emission. The little wind tunnel system consisted of plastic canopy covering the treatment area (2 m long by 0.5 m wide). By was using a fan, it was imitated the natural wind speed in the test area (1-1.5 m/s). Nitrogen losses were measured with this method in surface application, 50 mm and 100 mm subsurface. In the surface application, the highest ammonia emission was observed. It was approximately 68% higher in compared to another methods. There is significantly (P=0.05) different in the ammonia emission, between the surface apply method and injection manure in soil methods. But There isn’t any significantly different between ammonia emission amount in injection subsurface methods (100 mm and 50 mm deep).

Pure ammonia flames with high thermal intensities through fuel and air staging under extreme rich-to-lean conditions

Ammonia combustion has gained significant attention due to its high hydrogen content and zero carbon emissions. It poses a challenge for stabilization due to their low energy content and limited flammability range, with the added concern of fuel NOx emissions. In the current study, a novel burner design equipped with four series of reactors is proposed to achieve stable pure ammonia-air flames with reduced NOx emissions. The impact of thermal intensity (∼0.7 MW/m3 to ∼4 MW/m3), number of stages, equivalence ratio (0.5–1.2), and fuel staging on flame stabilization and emissions were investigated in the proposed burner. Comprehensive emissions analysis is performed at various burner levels. Numerical simulations incorporating Large Eddy Simulation (LES) modeling are employed to enhance understanding of the impact of thermal intensity and equivalence ratios on ammonia dissociation, mixedness, and NO emissions. The results indicated that the present burner design improved reactant mixing, and flame stability, reduced NH3 emissions (∼ 0 PPM), and lowered NOx levels in non-premixed ammonia-air flames. The computational and experimental results demonstrated that the implementation of fuel staging is crucial for reducing NOx emissions for the flames with lean global equivalence ratios. Lower NO emissions were identified at a global equivalence ratio of 1.1 for all the considered flames in the range of 0.5–1.2. In the four-stage rich-lean combustion strategy employed in this study; it was observed that higher thermal intensity (4 MW/m3) with fuel staging resulted in lower NOx emissions per kW of energy input compared to lower thermal intensities 0.7 MW/m3. This finding underscores the significance of achieving uniform mixtures and ensuring local flame in rich conditions for achieving low NOx emissions in ammonia combustion. Exhaust gas analysis is conducted at three stages of the burner to enhance the understanding of emissions at various levels of the burner. The proposed combustor design has achieved a substantial reduction in NOx to ∼1 PPM/kW and ∼2.8 PPM/kW with and without fuel staging, respectively. This impressive outcome is attributed to the controlled ammonia consumption facilitated by uniform mixing generated through the use of tangential air inlets.

REDUCING OF AMMONIA AND HYDROGEN SULFIDE EMISSION FROM CHICKEN LITTER BY THE USE OF INORGANIC AND BIOLOGICALLY ACTIVE SUBSTANCES

The accumulation of chicken litter, due to the excessive emission of gaseous air pollutants, causes a significant load on the environment. Therefore, the basis of research was to find out the level of NH3 and H2S emission from chicken litter by the influence of inorganic and biologically active substances. It is established that the lowest level of NH3 release from litter - by 25.5-32.6% and H2S by 19.7-24.4% is observed with the introduction of a complex preparation for deactivation of enzymatic processes in chicken litter. Of the studied natural sorbents, the best results for reducing NH3 and H2S emission from the litter were obtained by the use of vermiculite - by 24.4-28.7% and 12.6-15.9%. The biopreparation Kapeliukhiv Yarok more effectively affects the reduction of the NH3 release from the substrate (24.3-27.7%) and the Scarabei - H2S (16.1-19.2%). The introduction in chicken litter magnesium acetate and superphosphate helps to reduce NH3 emission by 22.2-22.8% and 22.3- 24.3%, while H2S by 16.0-19.2% and 16.3-17.2%.

Seasonal ammonia emissions from an intensive beef cattle feedlot in Victoria Australia

Ammonia (NH3) emitted from concentrated animal feeding operations can cause environmental and health problems, and indirectly contribute to greenhouse gas emissions. Cattle feedlots are known to be large sources of NH3, but few studies have documented seasonal emissions from Australian feedlots. We conducted two field campaigns to measure NH3 emissions from an intensive beef cattle feedlot in southeast Australia, and these results were combined with previous measurements at the same feedlot to document seasonal variations in emissions and to derive annual feedlot emission factors (EFs). Emission rates were calculated with an inverse dispersion modelling (IDM) technique, based on NH3 concentrations measured at the feedlot with open-path lasers (OPLs). The average area emission rates in spring, summer, autumn and winter were 90.5, 167.4, 96.2 and 86.8 μg NH3 m−2 s−1 from the cattle pens, and 22.5, 18.1, 7.7 and 20.7 μg NH3 m−2 s−1 from the manure stockpile area, respectively. The total per-animal EFs ranged from 126.0 (autumn) to 190.2 g NH3 animal−1 d−1 (summer), representing a loss of 47.5–64.6% of the fed N. Seasonal variations in emissions were related to air temperature. Slight changes in crude protein content of the cattle diet may also have impacted seasonal variability. Taking seasonal variations into consideration, the average feedlot EF was 160.4 g NH3 animal−1 d−1, with 90% of the emissions coming from the cattle pens. Extrapolating the EF to all feedlot cattle in the country, the direct NH3 emissions from Australian feedlots amount to 65.2 Gg NH3 annually, or 3.7% of the national total. Our study benchmarks seasonal and annual EFs and N losses for Australian commercial feedlots, and provides a baseline for extrapolating the impacts of mitigation efforts.

Study on lean combustion of ammonia-hydrogen mixtures in a pre-chamber engine

Ammonia holds promise for achieving zero carbon emissions from internal combustion engines. The pre-chamber turbulent jet ignition, characterized by multipoint distributed ignition and rapid combustion, could be applied to ammonia combustion to extend combustion limits and stability. This study investigates the impacts of hydrogen energy fraction (Hfrac), equivalence ratio, and ignition timing on the combustion and emission characteristics of ammonia-hydrogen mixture at lean combustion conditions in a pre-chamber (PC) marine engine by CFD Simulation. In H2-fuel active PC mode, increasing the hydrogen content or achieving stoichiometric combustion within the PC will shorten the cold jet phase and accelerate the formation of a more intense hot jet. As the Hfrac and the equivalence ratio in the main-chamber increase, the combustion pressure, temperature, and heat release rate (HRR) rise, while the combustion duration shortens due to enhanced reactivity, potentially leading to end gas auto-ignition and knock due to lower auto-ignition energy of the mixture. NO primarily forms near the flame front, and both NO concentration and the generation area increase with an increase in hydrogen content and equivalence ratio. Fuel-NO is likely to be the dominant factor in NO generation with lean combustion conditions. N2O, as a product of NH3 low-temperature combustion, is mainly concentrated near the flame front. An increase in unburned NH3 emissions corresponds to an increase in N2O emissions. Delaying the ignition timing to reduce NOx emissions is primarily achieved by controlling NO emissions, even though there is a slight increase in N2O.

Gaseous carbon and nitrogen emissions from microbial fuel cell-constructed wetlands with different carbon sources: Microbiota-driven mechanisms

As co-substrate, a carbon source is a crucial factor impacting the performance and process of microbial fuel cell-constructed wetlands (MFC-CWs). However, there is limited information regarding how different carbon sources regulate the emission of carbon and nitrogen gases from MFC-CWs. This study explored how the type of carbon source regulates the emission of carbon and nitrogen gases in MFC-CWs. Four types of carbon sources (i.e., glucose, sodium acetate, sucrose, and starch) were examined and evaluated for their pollutant removal efficiency and carbon and nitrogen gas emission characteristics in MFC-CWs. The results showed that the specific carbon source significantly influenced the performance of MFC-CWs, where electron transfer regulated denitrification, methane (CH4) production, and respiration. Glucose emerged as the most effective carbon source, enhancing COD (86.77%) and TN (93.85%) removal efficiency, while sucrose was effective for NH4+-N (93.79%) removal, and starch was beneficial for TP (91.99%) removal. In terms of gaseous emissions, MFC-CWs with glucose as a carbon source significantly (p < 0.05) promoted CH4 emission by regulating the abundance of mcrA and pmoA genes, and significantly (p < 0.05) suppressed CO2, N2O, and NH3 emissions by affecting nir and nosZ genes and electron competition. Overall, glucose was more effective than other carbon sources in promoting denitrification and reducing global warming potential (GWP). Our findings confirm the vital role of carbon sources in controlling nitrogen removal, carbon consumption, and gas emission reduction in microbial processes.

Establish of air pollutants and greenhouse gases emission inventory and co-benefits of their reduction of transportation sector in Central China

Recently, the transportation sector in China has gradually become the main source of urban air pollution and primary driver of carbon emissions growth. Considering air pollutants and greenhouse gases come from the same emission sources, it is necessary to establish an updated high-resolution emission inventory for the transportation sector in Central China, the most polluted region in China. The inventory includes on-road mobile, non-road mobile, oil storage and transportation, and covers 9 types of air pollutants and 3 types of greenhouse gases. Based on the Long-range Energy Alternatives Planning System (LEAP) model, the emissions of pollutants were predicted for the period from 2020 to 2035 in different scenarios. Results showed that in 2020, emissions of SO2, NOx, CO, PM10, PM2.5, VOCs, NH3, BC, OC, CO2, CH4, and N2O in Henan Province were 27.5, 503.2, 878.6, 20.1, 17.4, 222.1, 21.5, 9.4, 2.9, 92,077.9, 6.0, and 10.4 kilotons, respectively. Energy demand and pollutant emissions in Henan Province are simulated under four scenarios (Baseline Scenario (BS), Pollution Abatement Scenario (PA), Green Transportation Scenario (GT), and Reinforcing Low Carbon Scenario (RLC)). The collaborative emission reduction effect is most significant in the RLC scenario, followed by the GT scenario. By 2035, under the RLC scenario, energy consumption and emissions of SO2, NOx, CO, PM10, PM2.5, VOCs, NH3, CO2, CH4, and N2O are projected to decrease by 72.0%, 30.0%, 55.6%, 56.0%, 38.6%, 39.7%, 51.5%, 66.1%, 65.5%, 55.4%, and 52.8%, respectively. This study provides fundamental data support for subsequent numerical simulations.

Ammonia Volatilization from Pig Slurries in a Semiarid Agricultural Rainfed Area

Slurries are one of the main NH3 emission sources. Nitrogen losses impact air quality, and they constrain the sustainability of farming activities. In a rainfed Mediterranean agricultural system, the aim was to quantify NH3 emissions at a time when plants do not yet cover the soil surface and according to fertilization practices. One treatment was slurry from fattening pigs (PSF) applied before cereal sowing and incorporated into the soil; two treatments were PSF or from sows (PSS) applied at the cereal tillering stage (topdressing); and two more treatments received slurries twice, before sowing and as topdressing. Ammonia emissions were quantified with semi-static chambers during 145 h (before sowing) and 576 h (at cereal tillering) after slurry application. Before sowing, tillage after slurry application controlled NH3-N emissions, but they accounted for 14% of the total NH4-N applied. At tillering, average NH3-N emissions also accounted for ca. 14% of total NH4-N applied as PSF or PSS, respectively. Slurry dry matter from 84 kg m−3 (PSS) up to 127 kg m−3 (PSF), combined with low soil moisture content (below 30% of water holding capacity) at application time, helped in NH3 emission control. Slurry applications before sowing did not enhance later NH3-N emissions at topdressing.

Impact of operation parameters and lambda input signal during lambda-dithering of three-way catalysts for low-temperature performance enhancement

A synthetic exhaust gas bench was dynamically operated to investigate the impact of temperature, amplitude, split cycle, mean lambda, gas hourly space velocity, and oxygen storage capacity on average pollutant conversion and product selectivity of three-way catalysts in periodic operation. As temperature and amplitude increase and oxygen storage capacity decreases, the optimal frequency for maximum pollutant conversion increases. This is consistent with faster desorption of CO and O2 from the catalyst, yielding free surface sites. Regarding the formation of secondary products, the optimal frequency for maximum pollutant conversion does not always correspond to minimal N2O and NH3 emissions. The split cycle variation reveals the enhancement of C3H8 and NO conversion after both lean-rich and rich-lean switches and C3H6 and CO conversion after rich-lean switches at the optimal frequency. As periodic operation does not affect existing engine settings or operating conditions, it is a cost-effective control strategy for meeting future emission limits.

Anomalous increase in global atmospheric ammonia during COVID-19 lockdown: Need policies to curb agricultural emissions

The restrictions imposed on human activities during the COVID-19 lockdown (LD) period provided a new scenario to identify potential sources of atmospheric pollution. There are several studies that deal with changes in air quality around the world during LD, but very few on atmospheric ammonia (NH3). Therefore, we examine the changes in global NH3 during LD (April–May 2020) in comparison to the pre-lockdown (PreLD, April–May 2017–2019) and post-lockdown (PostLD, April–May 2021) periods, and assess the factors responsible for these changes. We observe an increase in NH3 during LD across the latitudes, with very high values in the western Europe, Eastern China (EC), the Indian subcontinent and the eastern United States of America (USA). However, a decline in NH3 is observed in some regions of South America (SA) and North America (NA). Similar changes in NH3 during LD are also observed in smaller spatial scales, as found in 3000 cities across the globe. The reduction of sulphur dioxide (SO2), nitrogen dioxide (NO2), nitric acid (HNO3), humidity and cloud cover as a result of restrictions on human activities, particularly in the western Europe and the USA, may have impeded the conversion of NH3 to particulates, which led to a higher NH3 there. Nevertheless, agricultural activities and livestock are the most prominent sources of atmospheric NH3, and were not under restriction during LD, show an enhancement in terms of the use of nitrogen fertilizer, crop production and area harvested, which also cause a rise in NH3 in these regions. Therefore, it is evident that the changes in meteorology and atmospheric composition, together with increased agricultural activities, led to the global increase in atmospheric NH3 during LD. That is, most pollutants show a decline during LD, but NH3 exhibits a rise due to its sources such as agricultural activities. Henceforth, environmental regulations, policies and advanced technologies are required in the agricultural sector, such as fertilizer deep placement using urea briquettes and restricted application of nitrogen fertilizers, to curb NH3 emissions.

Spatial Distribution of Ammonia Concentrations and Modeled Dry Deposition in an Intensive Dairy Production Region.

Agriculture generates ~83% of total US ammonia (NH3) emissions, potentially adversely impacting sensitive ecosystems through wet and dry deposition. Regions with intense livestock production, such as the dairy region of south-central Idaho, generate hotspots of NH3 emissions. Our objective was to measure the spatial and temporal variability of NH3 across this region and estimate its dry deposition. Ambient NH3 was measured using diffusive passive samplers at 8 sites in two transects across the region from 2018-2020. NH3 fluxes were estimated using the Surface Tiled Aerosol and Gaseous Exchange (STAGE) model. Peak NH3 concentrations were 4-5 times greater at a high-density dairy site compared to mixed agriculture/dairy or agricultural sites, and 26 times greater than non-agricultural sites with prominent seasonal trends driven by temperature. Annual estimated dry deposition rates in areas of intensive dairy production can approach 45 kg N ha-1 y-1, compared to <1 kg N ha-1 y-1 in natural landscapes. Our results suggest that the natural sagebrush steppe landscapes interspersed within and surrounding agricultural areas in southern Idaho receive NH3 dry deposition rates within and above the range of nitrogen critical loads for North American deserts. Finally, our results highlight a need for improved understanding of the role of soil processes in NH3 dry deposition to arid and sparsely vegetated natural ecosystems across the western US.

Methane and nitrous oxide emissions during biochar‐composting are driven by biochar application rate and aggregate formation

AbstractManure is a leading source of methane (CH4), nitrous oxide (N2O), and ammonia (NH3) emissions, and alternative manure management practices can help society meet climate goals and mitigate air pollution. Recent studies show that biochar‐composting can substantially reduce emissions from manure. However, most studies test only one type of biochar applied at a single application rate, leading to high variation in emission reductions between studies. Here, we measured greenhouse gas and NH3 emissions during biochar‐composting of dairy manure with biochar applied at 5% or 20%, by mass, and made from walnut shells, almond shells, or almond clippings. We found little difference in emissions between biochar type. However, we found that the 20% application rates increased CH4 emissions and decreased N2O and NH3 emissions, resulting in a net reduction in global warming potential (GWP). We attribute this result to biochar increasing the formation of compost aggregates, which likely acted as anaerobic reactors for methanogenesis and complete denitrification. Biochar may have further fueled CH4 production and N2O consumption by acting as an electron shuttle within aggregates. We recommend lower application rates, as we found that the 5% treatments in our study led to a similar reduction in GWP without increasing CH4 emissions.

Soil greenhouse gas flux and nitrogen mineralization following manure application from tannin-fed dairy cows.

Growing concerns about environmental impacts of dairy farms have driven producers to address greenhouse gas (GHG) emissions and nitrogen (N) losses from soil following land application of dairy manure. Tannin dietary additives have proved to be a successful intervention for mitigating GHG and ammonia (NH3 ) emissions at the barn scale. However, it is unknown how land application of dairy manure from cows fed tannin diets affects crop-soil nitrogen dynamics and soil GHG flux. To test this, cows were fed diets at three levels of tannins (0.0%, 0.4%, and 1.8% of dry matter intake) and their manure was field applied at two N rates (240 and 360kg N ha-1 ). Soil NH4 + -N, NO3 - -N, corn silage yield, and soil GHG flux were then measured over a full growing season. Soils amended with tannin manure had lower initial NH4 + -N concentrations and lower total mineral N (NH4 + -N + NO3 - -N) concentrations 19 days after application, compared to soils amended with no tannin manures. Despite lower early season N availability in tannin-fertilized plots, there were no differences in corn silage yield. No differences in soil GHG and NH3 emissions were observed between manure-amended treatments. These results demonstrate that while tannin addition to dairy cow feed does not offer short-term GHG or NH3 emissions reductions after field manure application, it can promote slower soil N mineralization that may reduce reactive N loss after initial application.

Effect of a semi-permeable membrane covered composting on greenhouse gas emissions and bacterial community succession: A comparative study with biomass materials covering

This study investigated the effects of cornstalk, sawdust, and semi-permeable membrane covering on gaseous emissions and bacterial communities during composting, and the physicochemical and biodegradable characteristics of covered compost piles. The results showed that cornstalk covering increased NH3 emissions by 1.5% and reduced N2O emissions by 47.0%, and the sawdust covering synergistically reduced NH3 and N2O emissions by 42.1% and 23.2%, respectively. The biomass materials covering reduced gaseous emissions through physical adsorption and biotransformation. Total nitrogen (TN) emissions increased from 12.50 to 35.90 g kg−1 for cornstalk and from 1.60 to 7.10 g kg−1 for sawdust, while the nitrogen-reducing bacteria substantially increased from 0.21–0.28% to 1.98–2.44% in biomass covering materials. The biomass materials covering increased electrical conductivity and reduced the diversity and network complexity of bacterial communities in compost. Finally, the lignocellulosic structure and functional groups of the biomass materials were destroyed, thus biomass material could not be reused. Correspondingly, the membrane covering simultaneously decreased NH3 emissions by 53.9% and N2O emissions by 71.3%. In addition to physical interception, the nitrogen-reducing bacterial communities enriched on the membrane surface (Georgenia and Limnobacter) further reduced NH3 and N2O emissions. The bacterial communities in membrane-covered treatment exhibited concentrated connections and potential cooperation. As a result, the membrane covering achieved higher maturity and better reduction performance of gaseous emissions. Characterization of covering materials revealed that the membrane structure was intact and could be reused. Interestingly, after composting, the membrane surface formed a “microbe-rich biofilm”, which exhibited better performance in subsequent covering processes.

A combination of straw incorporation and polymer-coated urea offsets soil ammonia and nitrous oxide emissions in winter wheat fields

The combined effects of straw incorporation (SI) and polymer-coated urea (PCU) application on soil ammonia (NH3) and nitrous oxide (N2O) emissions from agricultural fields have not been comprehensively evaluated in Northwest China. We conducted a two-year field experiment to assess the effects of combining SI with either uncoated urea (U) or PCU on soil NH3 emissions, N2O emissions, winter wheat yields, yield-scaled NH3 (INH3), and yield-scaled N2O (IN2O). Five treatments were investigated, no nitrogen (N) fertilizer (N0), U application at 150 kg N ha–1 with and without SI (SI+U and S0+U), and PCU application at 150 kg N ha–1 with and without SI (SI+PCU and S0+PCU). The results showed that the NH3 emissions increased by 20.98–34.35% following SI compared to straw removal, mainly due to increases in soil ammonium (NH4+-N) content and water-filled pore space (WFPS). SI resulted in higher N2O emissions than under the S0 scenario by 13.31–49.23% due to increases in soil inorganic N (SIN) contents, WFPS, and soil microbial biomass. In contrast, the PCU application reduced the SIN contents compared to the U application, reducing the NH3 and N2O emissions by 45.99–58.07 and 18.08–53.04%, respectively. Moreover, no significant positive effects of the SI or PCU applications on the winter wheat yield were observed. The lowest INH3 and IN2O values were observed under the S0+PCU and SI+PCU treatments. Our results suggest that single PCU applications and their combination with straw are the optimal agricultural strategies for mitigating gaseous N emissions and maintaining optimal winter wheat yields in Northwest China.

Interannual variability of atmospheric ammonia over the Sichuan Basin, southwestern China: Trend, sources, and implications on particle matter control

Atmospheric ammonia (NH3) is an important constituent of biogeochemical cycle and excessive NH3 in the environment results in detrimental effects on ecosystems, air quality, and human health. However, interannual variability and emission changes of NH3 remain highly uncertain, particularly for NH3 hotspot areas. Here, we identify the emission hotspots of NH3 and reveal the trend of NH3 emissions over the Sichuan Basin (SCB) based on a high-resolution map from infrared Atmospheric Sounding Interferometer (IASI) satellite observations in combination with the MEIC inventory from 2008 to 2019. IASI observations indicate that NH3 columns persistent increase over time while MEIC inventory suggests that the past increase in NH3 emissions has indeed ended in 2017 and exhibit decreasing trend afterwards. The NH3 hotspots derived from IASI mainly concentrate in the Chengdu Plain and southern SCB city cluster, which mostly agrees with MEIC emission inventory. CMAQ model simulations well reproduce PM2.5 and ammonia loading and capture observed patterns of NH3. We find that ammonium makes up 15–35% of inorganic fine PM2.5 mass in winter over the SCB. Regulation efforts focused on joint reducing 30% of NOx, SO2, and NH3 emissions could lead to basin-wide wintertime PM2.5 reduce by 10.0 μg/m3, while cutting 30% emissions of NH3 or NOx alone only yield PM2.5 reduced by 0.8 and 5.0 μg/m3, respectively. This work contributes insights on the trend and spatial pattern of NH3 source over the SCB and reveals the critical role of regulating NH3 emissions in mitigating PM2.5 pollution, shedding insights on nitrogen management strategies

Setting goals for agricultural nitrogen emission reduction to ensure safe air and groundwater quality: A case study of Quzhou, the North China Plain

Setting nitrogen (N) emission targets for agricultural systems is crucial to prevent to air and groundwater pollution, yet such targets are rarely defined at the county level. In this study, we employed a forecasting-and-back casting approach to establish human health-based nitrogen targets for air and groundwater quality in Quzhou county, located in the North China Plain. By adopting the World Health Organization (WHO) phase I standard for PM2.5 concentration (35 μg m−3) and a standard of 11.3 mg NO3−-N L−1 for nitrate in drinking water, we found that ammonia (NH3) emissions from the entire county must be reduced by at least 3.2 kilotons year−1 in 2050 to meet the WHO's PM2.5 phase I standard. Additionally, controlling other pollutants such as sulfur dioxide (SO2) and nitrogen oxides (NOx) is necessary, with required reductions ranging from 16% to 64% during 2017–2050. Furthermore, to meet the groundwater quality standard, nitrate nitrogen (NO3−-N) leaching to groundwater should not exceed 0.8 kilotons year-1 by 2050. Achieving this target would require a 50% reduction in NH3 emissions and a 21% reduction in NO3−-N leaching from agriculture in Quzhou in 2050 compared to their respective levels in 2017 (5.0 and 2.1 kilotons, respectively). Our developed method and the resulting N emission targets can support the development of environmentally-friendly agriculture by facilitating the design of control strategies to minimize agricultural N losses.

Update of the year 2019 modeling emission inventory in China

Using updated emission inventories can enhance the accuracy of air quality forecast models. Given China’s rapid economic growth and Korea’s geographical and meteorological position on the windward side of China, updating China’s emission inventory has become particularly crucial for Korea’s air quality modeling. This study aimed to develop an updated version of China’s Emission Inventory in Comprehensive Regional Emissions for Atmospheric Transport Experiments version 3 for the base year of 2019 (CREATEv3 (YR 2019)). To achieve this goal, we utilized the Chinese emission inventory of CREATEv3 for the base year of 2015 (CREATEv3 (YR 2015)) as a framework to incorporate the latest Chinese emission data from the Multi-resolution Emission Inventory Model for Climate and Air Pollution Research for the base year of 2019 (MEIC COVID-19 (YR 2019)) and update the inventory. The updated China’s annual emissions are now reflected in CREATEv3 (YR 2019), and the amounts are as follows: 132 Tg for CO, 21 Tg for NOx, 8 Tg for SO2, 7 Tg for PM2.5, 9 Tg for NH3, and 28 Tg for volatile organic compound (VOC). By comparing previous Chinese emission inventories with the updated inventory developed in this study, it was found that SO2, NOx, VOC, and NH3 emissions were decreased. Therefore, using the updated inventory seemingly reduces the impact of China’s fine dust on Korea. By comparing emissions by pollutant and region in China using CREATEv3 (YR 2019), it was found that regions with high emissions of targeted pollutants strongly correlated with major industries operating in those areas. This study is expected to provide insights into China’s emission changes in 2019 and support air quality forecasting.

Effects of ammonia energy fraction and diesel injection parameters on combustion stability and GHG emissions characteristics in a low-loaded ammonia/diesel dual-fuel engine

Ammonia, as a zero-carbon and widely sourced hydrogen carrier fuel, will play an important role in the decarbonization process of internal combustion engines, and the dual-fuel RCCI mode is a potential ammonia combustion technology route. In this study, ammonia/diesel dual-fuel (ADDF) combustion mode was implemented on a modified common-rail diesel engine, and the effects of ammonia energy fraction (AEF), diesel injection pressure (DIP), and diesel injection timing (DIT) on in-cylinder combustion, pollutant emissions and greenhouse effect of dual-fuel engine were investigated. The results indicated that the combustion process of ADDF was limited by the inert combustion and inhibitory effects of ammonia fuel. With the increase of AEF, the dual-fuel combustion process was delayed, the peak in-cylinder pressure decreased, and the ignition delay and combustion duration significantly increased, which was not conducive to the improvement of brake thermal efficiency (BTE). The introduction of ammonia fuel significantly reduced NOx, Soot and CO2 emissions, while unburned NH3 and N2O emissions sharply increased. At AEF = 60 %, CO2 emission decreased by 50.2 %, however, the in-cylinder combustion process deteriorated severely, with cyclic fluctuations reaching 5.06 %. Both increasing DIP and advancing DIT enhanced the chemical reactivity of in-cylinder mixture of ADDF engine, leading to earlier combustion heat release phase and shorter ignition delay, and reducing the variation of combustion cycle. Meanwhile, there was still a trade-off relationship between NOx and Soot emissions. When DIP increased from 100 MPa to 130 MPa, NH3 emission decreased by 20.8 %. Further increasing the DIP to 140 MPa would result in serious “wet wall” problems, leading to an increase in the incomplete combustion area and a decrease in BTE. When DIT was advanced from −4 °CA ATDC to −12 °CA ATDC, CO, HC and NH3 emissions decreased by 71.3 %, 52.7 % and 57.6 %, respectively, while N2O emission increased by 19.9 %, resulting in an increase in equivalent CO2 emissions. Under the optimized diesel injection strategy, the BTE of ADDF engine was 31.9 %, significantly higher than the original engine operating condition (BTE = 30.2 %).