Source Of NH3 Research Articles

Assessing the Iterative Finite Difference Mass Balance and 4D‐Var Methods to Derive Ammonia Emissions Over North America Using Synthetic Observations

AbstractWe evaluate two inverse modeling methods by conducting inversion experiments using the GEOS‐Chem chemical transport model and its adjoint. We simulate synthetic NH3 column density as observed by the Cross‐track Infrared Sounder over North America to test the ability of the iterative finite difference mass balance (IFDMB) and the four‐dimensional variational assimilation (4D‐Var) methods to recover known NH3 emissions. Comparing to the more rigorous 4D‐Var method, the IFDMB approach requires 3–4 times lower computational cost and yields similar or smaller errors (12–17% vs 17–26%) in the top‐down inventories at 2° × 2.5° resolution. These errors in IFDMB‐derived emission estimates are amplified (53–62%) if compared to the assumed true emissions at 0.25° × 0.3125° resolution. When directly conducting inversions at 0.25° × 0.3125°, the IFDMB consistently exhibits larger errors (44–69% vs 30–45%) than the 4D‐Var approach. Analysis of simulated differences in NH3 columns and in NH3 emissions suggests stronger misalignments at the finer resolution, since the local column is more strongly influenced by spatial smearing from neighboring grids. Adjoint calculations indicate that the number of adjacent grids needed to account for most (>65%) of the emission contributions to the local columnar NH3 abundance over an NH3 source site increases from ~1 at 2° × 2.5° to ~10 at 0.25° × 0.3125°, leading to increased errors especially in IFDMB. Applying inversion results at 2° × 2.5° to update the a priori emissions at 0.25° × 0.3125° could improve the accuracy of IFDMB inversions and reduce the computational cost of 4D‐Var.

High time-resolved measurements of water-soluble sulfate, nitrate and ammonium in PM2.5 and their precursor gases over the Eastern Mediterranean

High time-resolved measurements of aerosol SO42−, NO3−, NH4+ and their precursor gases HNO3, SO2, NH3 between 27 and 02 January/February and 19–01 August/September 2015 were carried out by applying AIM-IC at a rural site located on the coast of the Eastern Mediterranean, Erdemli, Turkey. The comparison between online and offline techniques revealed better correlation coefficients for SO42− and NH4+ (r > 0.90) than that of NO3− (0.63). Mean concentrations of water-soluble species were found in decreasing order SO42− (2814 ng m−3) > NH4+ (1371 ng m−3) > NO3− (495 ng m−3). NH3 (3390 ng m−3) concentration was more than enough to neutralize SO2 (879 ng m−3) and HNO3 (346 ng m−3). The gas-to-particle conversion ratios (>0.3) implied that SO42−, NO3− and NH4+ were mainly influenced by non-local sources. SO42−, NO3−, NH4+, HNO3, SO2 exhibited remarkable decrease (leastways 40%) in the atmosphere over the Eastern Mediterranean throughout fifteen years. In winter, day time NH3 concentrations illustrated significant relationship with temperature (positive) and humidity (negative), implying evaporation of dew or emission from plant stoma. Whereas, diurnal cycle of SO42− and SO2 was considerably influenced by populated City of Mersin in winter. During summer, HNO3 and SO2 (r = 0.74) demonstrated similar diurnal cycle, suggesting a common source for these precursor gases whilst NH3 was considerably affected by biomass burning emissions. Variability of all species was governed by local or nearly mesoscale transport in winter possibly due to frequent rain events. In summer, air flow from Eastern Mediterranean denoted aged air masses (GPC > 0.65) containing rather uniform concentrations of SO42− (~65 nmol m−3) and NH4+ (~140 nmol m−3). The highest NH3 along with the greatest % KBB contribution to PM2.5 mass was observed under the influence of Northerly airflow, exhibiting significance of biomass burning emissions as a source of NH3 in summer.

Atmospheric ammonia (NH3) emanations from Lake Natron\u2019s saline mudflats

In a recent global analysis of satellite-derived atmospheric NH3 data, a hotspot was observed in the vicinity of Lake Natron, Tanzania. The lake is in the centre of an endorheic (limited drainage) basin and has shallow, saline-alkaline waters. Its remote location and the absence of nearby large anthropogenic sources suggest that the observed NH3 is mainly of natural origin. Here we explore 10 years of IASI NH3 satellite data and other publicly available datasets over the area to characterize the natural NH3 emissions in this unique ecosystem. Temporal analysis reveals that the emissions are episodic and linked with the lake’s surface area. The largest NH3 column loadings generally occur at the end of the dry season in September–November over Lake Natron’s largest mudflat, that is exposed with receding water levels. The timing is different from the agricultural dominated NH3 emissions in the wider Natron area, which peak early in the year, after the first wet season. The likely source of NH3 at Lake Natron is decomposition of organic material, either from rivers and springs or produced in the lake (plankton, bird excreta). High temperatures and alkalinity are known to promote NH3 losses from soda lakes. We formulate six processes that may explain why the largest losses are observed specifically over concentrated brines and/or exposed sediments. As a by-product, we also show that hyperspectral infrared sounders such as IASI are capable of mapping different types of evaporative minerals such as trona and thermonatrite.

Ammonia exposure induced abnormal expression of cytokines and heat shock proteins via glucose metabolism disorders in chicken neutrophils.

Ammonia (NH3) is a highly irritant, alkaline gas. Atmospheric emission of NH3 was recognized as an environmental challenge. As a global issue, the NH3 emission survey with spatially detailed information demonstrated that the sources of atmospheric NH3 include agriculture (livestock wastes, fertilizers) and some industrial activities. As an environmental pollution, excessive NH3 exposure can induce many bird dysfunction. Neutrophils respond to multiple invading pathogens through different mechanisms. In order to investigate the effect of NH3 exposure on broilers' neutrophil, 1-day-old broilers were treated with/without NH3 for 28days. We extracted neutrophils from peripheral blood of chicken with/without NH3 exposure and subsequently stimulated with PMA. Changes of cytokines and inflammatory bodies, heat shock proteins (HSPs), and glucose metabolism of neutrophil were examined in both cases. We not only explored that the index associated with inflammation changed due to NH3 exposure but also observed the status of neutrophils which was treated with PMA stimulation. After NH3 exposure, IL-1β and IL-6 were significantly increased on broilers neutrophil. Inflammatory-related factors (NLRP3, ASC, and caspase-1) were significantly elevated. The mRNA expression of HSP70 and HSP90 was increased significantly. All glucose metabolism indicators were reduced. In summary, we concluded that NH3 enhanced inflammation and disrupted glucose metabolism, and increased the expression of HSPs and inflammatory factors. In addition, the sensitivity of neutrophils to exogenous stimuli was diminished. This information can not only be used to evaluate the damage of NH3-spiked neutrophils to chickens, but also provide clues for human health pathophysiology caused by excess NH3, providing valuable information for NH3 risk management.

Implementation of the effect of urease inhibitor on ammonia emissions following urea-based fertilizer application at a Zea mays field in central Illinois: A study with SURFATM-NH3 model

Agriculture is the main source of ammonia (NH3) emissions in the atmosphere. NH3 is precursor to secondary fine particulate matter, which is of concern for its impacts on health and visibility. There are a limited number of field measurements of NH3 emissions from fertilizer application in the US, and this limits our understanding of the importance of individual NH3 source and sink processes in controlling timing and magnitude of NH3 emissions. In this study, a new parameterization of the effect of urease inhibitor on NH3 emissions from urea-based fertilizer was developed on the basis of experimental results found in the literature. This parameterization was combined with an existing operational parameterization of soil and stomatal emission potentials (Γg, Γs) and was implemented in a surface-atmosphere transfer model for NH3 (SURFATM-NH3) in order to evaluate the bi-directional fluxes of NH3 at the field scale. The model was evaluated with field measurements obtained by the flux-gradient (FG) and relaxed eddy accumulation (REA) methods in a fertilized corn field in central Illinois. By integrating the effect of urease inhibitor, the timing of the highest NH3 emission peak was successfully predicted and its magnitude was close to that measured (predicted 2106 ng m−2 s−1, measured by FG 2312 ± 582 ng m−2 s−1). Based on the model results, urease inhibitor has a considerable effect on the dynamics and order of magnitude of NH3 fluxes. Furthermore, the model simulated the inhibiting action of N-(n-butyl) thiophosphoric (nBTPT) and suggests that it can reduce NH3 volatilization by 32%. The model also successfully predicted environmental parameters, such as soil temperature. Finally, this new version of SURFATM-NH3 is a valuable tool to estimate the NH3 bi-directional fluxes at the field scale, which describes dynamic modeling of Γs and Γg by taking into account the effect of urease inhibitor which is commonly used in the US to improve the efficiency of urea fertilizers.

Seasonal pattern of ammonium 15N natural abundance in precipitation at a rural forested site and implications for NH3 source partitioning

Excess ammonia (NH3) emissions and deposition can have negative effects on air quality and terrestrial ecosystems. Identifying NH3 sources is a critical step for effectively reducing NH3 emissions, which are generally unregulated around the world. Stable nitrogen isotopes (δ15N) of ammonium (NH4+) in precipitation have been directly used to partition NH3 sources. However, nitrogen isotope fractionation during atmospheric processes from NH3 sources to sinks has been previously overlooked. Here we measured δ15NNH4+ in precipitation on a daily basis at a rural forested site in Northeast China over three years to examine its seasonal pattern and attempt to constrain the NH3 sources. We found that the NH4+ concentrations in precipitation ranged from 5 to 1265 μM, and NH4+ accounted for 65% of the inorganic nitrogen deposition (20.0 kg N ha−1 yr−1) over the study period. The δ15N values of NH4+ fluctuated from −24.6 to +16.2‰ (average −6.5‰) and showed a repeatable seasonal pattern with higher values in summer (average −2.3‰) than in winter (average −16.4‰), which could not be explained by only the seasonal changes in the NH3 sources. Our results suggest that in addition to the NH3 sources, isotope equilibrium fractionation contributed to the seasonal pattern of δ15NNH4+ in precipitation, and thus, nitrogen isotope fractionation should be considered when partitioning NH3 sources based on δ15NNH4+ in precipitation.

Assessing Contributions of Agricultural and Nonagricultural Emissions to Atmospheric Ammonia in a Chinese Megacity.

Ammonia (NH3) is the predominant alkaline gas in the atmosphere contributing to formation of fine particles-a leading environmental cause of increased morbidity and mortality worldwide. Prior findings suggest that NH3 in the urban atmosphere derives from a complex mixture of agricultural (mainly livestock production and fertilizer application) and nonagricultural (e.g., urban waste, fossil fuel-related emissions) sources; however, a citywide holistic assessment is hitherto lacking. Here we show that NH3 from nonagricultural sources rivals agricultural NH3 source contributions in the Shanghai urban atmosphere. We base our conclusion on four independent approaches: (i) a full-year operation of a passive NH3 monitoring network at 14 locations covering urban, suburban, and rural landscapes; (ii) model-measurement comparison of hourly NH3 concentrations at a pair of urban and rural supersites; (iii) source-specific NH3 measurements from emission sources; and (iv) localized isotopic signatures of NH3 sources integrated in a Bayesian isotope mixing model to make isotope-based source apportionment estimates of ambient NH3. Results indicate that nonagricultural sources and agricultural sources are both important contributors to NH3 in the urban atmosphere. These findings highlight opportunities to limit NH3 emissions from nonagricultural sources to help curb PM2.5 pollution in urban China.

Satellite evidence of substantial rain-induced soil emissions of ammonia across the Sahel

Abstract. Atmospheric ammonia (NH3) is a precursor to fine particulate matter formation and contributes to nitrogen (N) deposition, with potential implications for the health of humans and ecosystems. Agricultural soils and animal excreta are the primary source of atmospheric NH3, but natural soils can also be an important emitter. In regions with distinct dry and wet seasons such as the Sahel, the start of the rainy season triggers a pulse of biogeochemical activity in surface soils known as the Birch effect, which is often accompanied by emissions of microbially produced gases such as carbon dioxide and nitric oxide. Field and lab studies have sometimes, but not always, observed pulses of NH3 after the wetting of dry soils; however, the potential regional importance of these emissions remains poorly constrained. Here we use satellite retrievals of atmospheric NH3 using the Infrared Atmospheric Sounding Interferometer (IASI) regridded at 0.25∘ resolution, in combination with satellite-based observations of precipitation, surface soil moisture, and nitrogen dioxide concentrations, to reveal substantial precipitation-induced pulses of NH3 across the Sahel at the onset of the rainy season in 2008. The highest concentrations of NH3 occur in pulses during March and April when NH3 biomass burning emissions estimated for the region are low. For the region of the Sahel spanning 10 to 16∘ N and 0 to 30∘ E, changes in NH3 concentrations are weakly but significantly correlated with changes in soil moisture during the period from mid-March through April when the peak NH3 concentrations occur (r=0.28, p=0.02). The correlation is also present when evaluated on an individual pixel basis during April (r=0.16, p<0.001). Average emissions for the entire Sahel from a simple box model are estimated to be between 2 and 6 mg NH3 m−2 d−1 during peaks of the observed pulses, depending on the assumed effective NH3 lifetime. These early season pulses are consistent with surface observations of monthly concentrations, which show an uptick in NH3 concentration at the start of the rainy season for sites in the Sahel. The NH3 concentrations in April are also correlated with increasing tropospheric NO2 concentrations observed by the Ozone Monitoring Instrument (r=0.78, p<0.0001), which have previously been attributed to the Birch effect. Box model results suggest that pulses occurring over a 35-day period in March and April are responsible for roughly one-fifth of annual emissions of NH3-N from the Sahel. We conclude that precipitation early in the rainy season is responsible for substantial NH3 emissions in the Sahel, likely representing the largest instantaneous fluxes of gas-phase N from the region during the year.

δ15N of lichens reflects the isotopic signature of ammonia source

Although it is generally accepted that δ15N in lichen reflects predominating N isotope sources in the environment, confirmation of the direct correlation between lichen δ15N and atmospheric δ15N is still missing, especially under field conditions with most confounding factors controlled. To fill this gap and investigate the response of lichens with different tolerance to atmospheric N deposition, thalli of the sensitive Evernia prunastri and the tolerant Xanthoria parietina were exposed for ten weeks to different forms and doses of N in a field manipulation experiment where confounding factors were minimized. During this period, several parameters, namely total N, δ15N and chlorophyll a fluorescence, were measured. Under the experimental conditions, δ15N in lichens quantitatively responded to the δ15N of released gaseous ammonia (NH3). Although a high correlation between the isotopic signatures in lichen tissue and supplied N was found both in tolerant and sensitive species, chlorophyll a fluorescence indicated that the sensitive species very soon lost its photosynthetic functionality with increasing N availability. The most damaging response to the different N chemical forms was observed with dry deposition of NH3, although wet deposition of ammonium ions had a significant observable physiological impact. Conversely, there was no significant effect of nitrate ions on chlorophyll a fluorescence, implying differential sensitivity to dry deposition versus wet deposition and to ammonium versus nitrate in wet deposition. Evernia prunastri was most sensitive to NH3, then NH4+, with lowest sensitivity to NO3−. Moreover, these results confirm that lichen δ15N can be used to indicate the δ15N of atmospheric ammonia, providing a suitable tool for the interpretation of the spatial distribution of NH3 sources in relation to their δ15N signal.

An Assessment of Low-Cost Techniques to Measure Ammonia Emission from Multi-Plots: A Case Study with Urea Fertilization

Ammonia (NH3) emission from agriculture is an environmental threat and a loss of nitrogen for crop production. Mineral fertilizers and manure are significant sources of NH3; therefore, abatement technologies have been introduced to mitigate these emissions. The aim of this study was to demonstrate that low-cost measuring techniques are suitable to assess NH3 emissions in smaller plots, appropriate to test different managements. Two experiments were established to quantify NH3 emissions from urea application in a multi-plot design with radii of 5 (R5) and 20 m (R20). Field was bare soil partially surrounded by shelterbelts. Measurement techniques included passive flux samplers (Leuning), and passive concentration samplers (ALPHA) coupled to WindTrax dispersion model. NH3 emission from R5 was consistent with the emission from R20 when the surface-to-atmosphere exchange was not affected by shelterbelts, and wind speed near surface was greater than 1 m s−1. Both measurement methods gave unreliable NH3 quantification in combination with wind speed lower than 1 m s−1 and low emission strength. Cumulative emission over 60 h was 2% of the supplied N from the plots not affected by the shelterbelt, and 1% from the plots affected by shelterbelts, indicating that these structures can significantly reduce NH3 emissions.

Characteristics and Sources of Atmospheric Inorganic Nitrogen Wet Deposition in Xueyu Cave Watershed, Outer Suburbs of Chongqing City

Xueyu Cave watershed is located in Fengdu County in the outskirts of Chongqing, where rainfall events were monitored continuously from July 2015 to December 2017. We explored the variation of mass concentration of atmospheric dissolved inorganic nitrogen (NH4+-N and NO3--N), and quantitatively calculated its wet deposition fluxes, then the sources of NH4+-N and NO3--N were tracked using the Xueyu cave air mass backward trajectory model. The results showed that:①During the monitoring period, the average annual dissolved inorganic nitrogen (DIN) deposition in the watershed was 14.25 kg·(hm2·a)-1, of which NH4+-N and NO3--N were 7.72 kg·(hm2·a)-1 and 6.53 kg·(hm2·a)-1, accounting for 54% and 46% of DIN wet precipitation, respectively, and indicating that NH4+-N is the dominant species, followed by NO3--N; ②DIN wet deposition flux and concentration showed marked seasonal changes. The DIN wet deposition flux in spring and summer was 50% higher than that in autumn and winter, while the DIN concentration of wet deposition in autumn and winter was 30% higher than those in spring and summer. ③NH4+-N/NO3--N was between 0.29 and 2.27, and NH4+-N/NO3--N > 1 during the rainy season (April to October) and NH4+-N/NO3--N < 1 during the dry season (November to March), indicating that the main sources of DIN wet deposition results from agricultural activities in the rainy season, and urban contributions in the dry season. ④In the study area, the southeastern winds are dominant in the rainy season but southwestern winds are dominant in the dry season. These determine the sources of DIN wet deposition (agricultural or urban).

Source Apportionment of Aerosol Ammonium in an Ammonia‐Rich Atmosphere: An Isotopic Study of Summer Clean and Hazy Days in Urban Beijing

AbstractAerosol ammonium (NH4+) can be a major component of fine particles, especially during severe haze episodes. The abatement of ammonia (NH3) emissions is important for reducing fine particles, but NH3 sources remain poorly constrained and are largely unregulated in China and most other regions. This study uses stable isotopes to interpret the role NH3 sources play in generating different sized NH4+ aerosols in Beijing between 21 June and 4 July 2013 with fine particle concentrations of 20–242 μg/m3. The concentrations and nitrogen stable isotope composition of aerosol NH4+ (δ15N‐NH4+) were both elevated during the five haze episodes that were sampled. These increases were driven by enhancements in the fine mode as opposed to substantial increases in the coarse mode aerosol. After accounting for the isotope fractionation that occurs during gas‐to‐particle partitioning (17.7‰ to 28.2‰), the “initial” (prepartitioning) δ15N‐NH3 values were estimated to be −35‰ for a clean period (i.e., a nonhazy day) and ranged from −14.3‰ to −22.8‰ for hazy days. Source apportionment using the “IsoSources” isotopic mixing model indicated that the dominant contribution to NH3 shifted from agricultural sources during the clean period (86%) to fossil fuel emissions (54%–81%) during hazy days and when back trajectories rotate from the northwest to the west and/or south. These results together suggest that even in summer, fossil fuel‐related sources from Beijing and the surrounding areas are the major source of NH3 during haze events and that controlling these sources may be important for alleviating particulate matter pollution.

Characteristics of Nitrogen Release at the Sediment-Water Interface in the Typical Tributaries of the Three Gorges Reservoir During the Sensitive Period in Spring

Overlying water and sediment interstitial water samples were acquired to study the nitrogen release between sediments and water interfaces in Xiangxi Bay in April 2016 during the Sensitive Period in spring. The spatial distribution of different forms of nitrogen in the sediment was analyzed, the diffusion fluxes of different forms of nitrogen in the sediments and water systems were also measured, and a correlation analysis with environmental factors was conducted. The results show that overlying water and sediment interstitial water ρ(TN) ranges from 1.10 to 6.90 mg·L-1 and 6.19 to 32.57 mg·L-1 respectively; indicating the nitrogen concentrations in the overlying and interstitial water of sediments have a certain variation along the process and vertically. The interstitial water nitrogen concentrations in the upstream area are higher than those in the downstream area. The interstitial water ρ(NH4+-N) in the sediment is significantly larger than that in the overlying water, but the interstitial water ρ(NO3--N) in the sediment is slightly smaller than that in the overlying water. Xiangxi Bay sediment acts as a source of NH4+-N; however, for NO3--N it is a sink. The diffusive fluxes of NH4+-N range from 2.70 to 4.72 mg·(m2·d)-1; and the diffusive fluxes of NO3--N range from -1.61 to -0.62 mg·(m2·d)-1. Nitrogen is mainly present in the form of ammonium nitrogen in the sediment of Xiangxi Bay. The ρ(NH4+-N) in the sediment ranges from 69.97-1185.97 mg·kg-1, ρ(NO3--N) ranges from 2.78-38.17 mg·kg-1, and the ρ(NH4+-N) in sediments in the surface at 0-8 cm changes with the same trend.

Identifying Ammonia Hotspots in China Using a National Observation Network.

The limited availability of ammonia (NH3) measurements is currently a barrier to understanding the vital role of NH3 in secondary aerosol formation during haze pollution events and prevents a full assessment of the atmospheric deposition of reactive nitrogen. The observational gaps motivated us to design this study to investigate the spatial distributions and seasonal variations in atmospheric NH3 on a national scale in China. On the basis of a 1-year observational campaign at 53 sites with uniform protocols, we confirm that abundant concentrations of NH3 [1 to 23.9 μg m-3] were identified in typical agricultural regions, especially over the North China Plain (NCP). The spatial pattern of the NH3 surface concentration was generally similar to those of the satellite column concentrations as well as a bottom-up agriculture NH3 emission inventory. However, the observed NH3 concentrations at urban and desert sites were comparable with those from agricultural sites and 2-3 times those of mountainous/forest/grassland/waterbody sites. We also found that NH3 deposition fluxes at urban sites account for only half of the emissions in the NCP, suggesting the transport of urban NH3 emissions to downwind areas. This finding provides policy makers with insights into the potential mitigation of nonagricultural NH3 sources in developed regions.

Contributions of natural and anthropogenic sources to ambient ammonia in the Athabasca Oil Sands and north-western Canada

Abstract. Atmospheric ammonia (NH3) is a short-lived pollutant that plays an important role in aerosol chemistry and nitrogen deposition. Dominant NH3 emissions are from agriculture and forest fires, both of which are increasing globally. Even remote regions with relatively low ambient NH3 concentrations, such as northern Alberta and Saskatchewan in northern Canada, may be of interest because of industrial oil sands emissions and a sensitive ecological system. A previous attempt to model NH3 in the region showed a substantial negative bias compared to satellite and aircraft observations. Known missing sources of NH3 in the model were re-emission of NH3 from plants and soils (bidirectional flux) and forest fire emissions, but the relative impact of these sources on NH3 concentrations was unknown. Here we have used a research version of the high-resolution air quality forecasting model, GEM-MACH, to quantify the relative impacts of semi-natural (bidirectional flux of NH3 and forest fire emissions) and direct anthropogenic (oil sand operations, combustion of fossil fuels, and agriculture) sources on ammonia volume mixing ratios, both at the surface and aloft, with a focus on the Athabasca Oil Sands region during a measurement-intensive campaign in the summer of 2013. The addition of fires and bidirectional flux to GEM-MACH has improved the model bias, slope, and correlation coefficients relative to ground, aircraft, and satellite NH3 measurements significantly. By running the GEM-MACH-Bidi model in three configurations and calculating their differences, we find that averaged over Alberta and Saskatchewan during this time period an average of 23.1 % of surface NH3 came from direct anthropogenic sources, 56.6 % (or 1.24 ppbv) from bidirectional flux (re-emission from plants and soils), and 20.3 % (or 0.42 ppbv) from forest fires. In the NH3 total column, an average of 19.5 % came from direct anthropogenic sources, 50.0 % from bidirectional flux, and 30.5 % from forest fires. The addition of bidirectional flux and fire emissions caused the overall average net deposition of NHx across the domain to be increased by 24.5 %. Note that forest fires are very episodic and their contributions will vary significantly for different time periods and regions. This study is the first use of the bidirectional flux scheme in GEM-MACH, which could be generalized for other volatile or semi-volatile species. It is also the first time CrIS (Cross-track Infrared Sounder) satellite observations of NH3 have been used for model evaluation, and the first use of fire emissions in GEM-MACH at 2.5 km resolution.

On-road emissions of ammonia: An underappreciated source of atmospheric nitrogen deposition

We provide updated spatial distribution and inventory data for on-road NH3 emissions for the continental United States (U.S.) On-road NH3 emissions were determined from on-road CO2 emissions data and empirical NH3:CO2 vehicle emissions ratios. Emissions of NH3 from on-road sources in urbanized regions are typically 0.1–1.3tkm−2yr−1 while NH3 emissions in agricultural regions generally range from 0.4–5.5tkm−2yr−1, with a few hotspots as high as 5.5–11.2tkm−2yr−1. Counties with higher vehicle NH3 emissions than from agriculture include 40% of the U.S. population. The amount of wet inorganic N deposition as NH4+ from the National Atmospheric Deposition Program (NADP) network ranged from 37 to 83% with a mean of 58.7%. Only 4% of the NADP sites across the U.S. had <45% of the N deposition as NH4+ based on data from 2014 to 2016, illustrating the near-universal elevated proportions of NH4+ in deposition across the U.S. Case studies of on-road NH3 emissions in relation to N deposition include four urban sites in Oregon and Washington where the average NH4-N:NO3-N ratio in bulk deposition was 2.3. At urban sites in the greater Los Angeles Basin, bulk deposition of NH4-N and NO3-N were equivalent, while NH4-N:NO3-N in throughfall under shrubs ranged from 0.6 to 1.7. The NH4-N:NO3-N ratio at 7–10 sites in the Lake Tahoe Basin averaged 1.4 and 1.6 in bulk deposition and throughfall, and deposition of NH4-N was strongly correlated with summertime NH3 concentrations. On-road emissions of NH3 should not be ignored as an important source of atmospheric NH3, as a major contributor to particulate air pollution, and as a driver of N deposition in urban and urban-affected regions.

Environmental Impacts of the Revised Emission Standard for Air Pollutants for Boilers during the Heating Season in Beijing, China

Beijing, the capital of China, revised the emission standard for air pollutants for boilers in 2015. To promote fulfillment of the new standard, the “coal to gas project” and the “reward replaces subsidy policy for low-NOx retrofits of boilers” were implemented recently, and the emission of pollutants from boilers has significantly changed as a result. In this study, a comprehensive unit-based emission inventory of multiple air pollutants, including PM10, PM2.5, CO, SO2, NOx, VOCs and NH3, from both coal-fired and gas-fired industrial boilers in Beijing in 2015 was established with data on annual activity and category-specific emission factors, and scenario analysis and the CMAQ model were used to forecast the environmental impacts of the revised standard during the heating season in Beijing. Our results showed that in 2015, the emissions of CO, NOx, PM2.5, PM10, SO2, NH3 and VOCs from the industrial boilers in Beijing were about 51,745 t, 27,943 t, 10,143 t, 14,624 t, 20,227 t, 197.55 t and 1304 t, respectively. Coal-fired boilers were the major source of CO, SO2, PM2.5 and PM10, while gas-fired boilers were the major source of VOCs and NH3. Furthermore, in IPC-1 and IPC-2 scenarios, which represent the different levels of implementation of the “low-NOx retrofits policy” as well as the replacement of all coal-fired boilers with gas-fired boilers, the ambient concentration of PM2.5 and SO2 was reduced by about 7.1% and 9.5%, respectively, and the concentration of NO2 was reduced by about 4.4% in IPC-1 and 3.7% in IPC-2 during the heating season in Beijing.

Pork production in Thuringia – management effects on ammonia and greenhouse gas emissions. 1. Depiction of the state in 2015

The formation of ammonia (NH3) and greenhouse gases (GHG) related to pork production is scrutinized in a fictitious enterprise that comprises 1,000 fattening places, the affiliated piglet and basic breeding herds as well as the herds of purebred grandparent animals. It also provides the necessary feed production as well as the provision of mineral fertilizers, lime, energy and water. Production conditions in the model reflect the situation in Thuringen (Thuringia), Germany. The most important NH3 sources are animal houses and mineral fertilizer application. GHG emissions arise mainly from feed production, in particular from the release of nitrous oxide. Within animal production itself, the majority of emissions are attributed to the fattening stage. They exceed those from piglet production. Emissions from basic breeding herds are almost negligible. However, it is inadequate to restrict estimates only to the fattening stage. Our results show clearly that potential emission reduction measures have to take the entire production chain into account.

Reply to Comment on “Identification of Major Sources of Atmospheric NH3 In An Urban Environment In Northern China During Wintertime”

ADVERTISEMENT RETURN TO ISSUEPREVCorrespondence/Rebut...Correspondence/RebuttalNEXTReply to Comment on “Identification of Major Sources of Atmospheric NH3 In An Urban Environment In Northern China During Wintertime”Qingjing Hu† and Xiaohong Yao*‡View Author Information† Key Laboratory of Sustainable Utilization of Marine Fisheries Resources, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China‡ Key Lab of Marine Environmental Science and Ecology (MoE), Ocean University of China, Qingdao 266100, China*Phone: 86-532-66782565; fax: 86-532-66782810; e-mail: [email protected]Cite this: Environ. Sci. Technol. 2018, 52, 1, 364–365Publication Date (Web):December 14, 2017Publication History Published online14 December 2017Published inissue 2 January 2018https://doi.org/10.1021/acs.est.7b05839Copyright © 2017 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views661Altmetric-Citations1LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (239 KB) Get e-AlertsSUBJECTS:Atmospheric chemistry,Computer simulations,Deposition,Nanogenerators,Particulate matter Get e-Alerts

Comment on "Identification of Major Sources of Atmospheric NH3 in an Urban Environment in Northern China During Wintertime".

Public concerns regarding atmospheric fine particles (PM2.5) have rapidly risen in recent years because of serious haze issues in urbanized regions, especially many Chinese metropolis regions. Atmospheric ammonia (NH3) is the main precursor of atmospheric particles.1 Unfortunately, the contribution of different anthropic or natural sources to atmospheric NH3 is still unclear.2 Source apportionment of atmospheric NH3 is an essential prerequisite of successful mitigation. “Identification of Major Sources of Atmospheric NH3 in an Urban Environment in Northern China During Wintertime” is an inspiring work that attempts to address this topic. However, some arguments in this article do not withstand serious scrutiny: