High Concentrations Of NH4 Research Articles

Soil nitrification response to dairy digestate and inorganic ammonium sources depends on soil pH and nitrifier abundances

AbstractTo reduce CH4 emissions, some dairy operations use manure as feedstock for anaerobic digesters, after which the nonvolatilized portion forms a digestate effluent with high NH4+ content that is used as fertilizer. When applied to soil, N fertilizers are subject to nitrification, where NH3–oxidizing archaea (AOA) and bacteria (AOB) oxidize NH3 to NO2–, NO2––oxidizing bacteria (NOB) oxidize NO2– to NO3−, and N oxides are produced from biotic and abiotic reactions. This study used soil microcosms to evaluate the properties of nitrification in response to the addition of N as digestate vs. NH4Cl in soils from the different climatic regions of the western Oregon coastal plain (CP) and eastern Oregon Columbia River basin (CRB). In each soil, properties of NH3 oxidation or N oxide accumulation did not differ when N was provided via digestate or NH4Cl over the normal temperature range; however, nitrification rates, communities, and products differed between soils. The average nitrification rate in CP soil was almost twofold higher than in CRB soil (P ≤ .001), despite no significant differences in AOB activity or AOB amoA copy numbers. With N addition, AOA activity also increased in CP soil, where AOA amoA copy numbers were fivefold higher than CRB soil (P < .002). Accumulation of NO2– only in CRB soil was likely due to NOB inhibition by high NH3 concentrations (∼560 μM) present at the high pH of CRB soil (8.5). Overall, nitrification was dictated by differences in edaphic properties, temperature, and nitrifier communities more than N source.

Biodegradation kinetics of ammonium enriched food waste digestate compost with biochar amendment

High concentration of NH4+-N in food waste digestate (FWD) produced from biological treatment of food waste is considered as a major threat on the composting process resulting in production of immature compost. Hence, a laboratory batch composting study was conducted to examine the feasibility of using biochar as a physical additive to ameliorate the inhibitory effect of NH4+-N and to mitigate the nitrogen loss during FWD composting. FWD was co-composted with tobacco biochar at a dosage of 0%, 2.5%, 5% or 10% (dw) in bench-scale composters with a controlled aeration system. The addition of 10% biochar enhanced the degradation rate resulting in 44% higher carbon decomposition than the control. Besides, 10% biochar amendment reduced NH3 and N loss by 58% and 5%, respectively and significantly reduced NH4+-N content to HKORC limit of < 700 mg/kg dw within 5 days showing the beneficiary impact of biochar addition.

Urban aerosol chemistry at a land–water transition site during summer – Part 1: Impact of agricultural and industrial ammonia emissions

Abstract. This study characterizes the impact of the Chesapeake Bay and associated meteorological phenomena on aerosol chemistry during the second Ozone Water-Land Environmental Transition Study (OWLETS-2) field campaign, which took place from 4 June to 5 July 2018. Measurements of inorganic PM2.5 composition, gas-phase ammonia (NH3), and an array of meteorological parameters were undertaken at Hart-Miller Island (HMI), a land–water transition site just east of downtown Baltimore on the Chesapeake Bay. The observations at HMI were characterized by abnormally high NH3 concentrations (maximum of 19.3 µg m−3, average of 3.83 µg m−3), which were more than a factor of 3 higher than NH3 levels measured at the closest atmospheric Ammonia Monitoring Network (AMoN) site (approximately 45 km away). While sulfate concentrations at HMI agreed quite well with those measured at a regulatory monitoring station 45 km away, aerosol ammonium and nitrate concentrations were significantly higher, due to the ammonia-rich conditions that resulted from the elevated NH3. The high NH3 concentrations were largely due to regional agricultural emissions, including dairy farms in southeastern Pennsylvania and poultry operations in the Delmarva Peninsula (Delaware–Maryland–Virginia). Reduced NH3 deposition during transport over the Chesapeake Bay likely contributed to enhanced concentrations at HMI compared to the more inland AMoN site. Several peak NH3 events were recorded, including the maximum NH3 observed during OWLETS-2, that appear to originate from a cluster of industrial sources near downtown Baltimore. Such events were all associated with nighttime emissions and advection to HMI under low wind speeds (&lt; 1 m s−1) and stable atmospheric conditions. Our results demonstrate the importance of industrial sources, including several that are not represented in the emissions inventory, on urban air quality. Together with our companion paper, which examines aerosol liquid water and pH during OWLETS-2, we highlight unique processes affecting urban air quality of coastal cities that are distinct from continental locations.

Strengthen “the sustainable farm” concept via efficacious conversion of farm wastes into methane

With escalating global demand for renewable energy, exploitation of farm wastes (i.e., agriculture straw wastes (ASWs), livestock wastewater (LW) and sewage sludge (SS)) has been considered to attain maximum methane yield (MY) via anaerobic digestion (AD). Results pointed that mixture of SS and LW as anaerobes’ source with 20 g of ASWs/300 mL of working volume achieved maximum MY and volatile solid (VS) removal efficiency of 0.44 (±0.05) L/gVS and 51.4 (±4.1)%, respectively. This was mainly because of emerging heavy duty bacterial species (i.e., Syntrophorhabdaceae and Synergistaceae) and archaeal community (i.e, Methanosarcina and Methanoculleus) after 70 days of anaerobic incubation. This was acquired along with boosting enzymatic activity, especially xylanase, cellulase and protease up to 71.5(±7.9), 179.3(±14.3) and 207.2(±16.2) U/100 mL, respectively. Furthermore, the digestate contained high concentrations of NH4+ (960.1±(76.8) mg/L), phosphorus (126.3±(10.1) mg/L) and trace metals, making it a good candidate as organic fertilizer.

Alternative splicing analysis of wheat glutamine synthase genes

<p id="C3">As a key enzyme for nitrogen assimilation in plant, glutamine synthetase (TaGS) is encoded by 12 genes in common wheat (<italic>Triticum aestivum</italic> L.), namely <italic>TaGS1;1-6A/6B/6D</italic>, <italic>TaGS1;2-4A/4B/4D</italic>, <italic>TaGS1;3-4A/4B/4D</italic>, and <italic>TaGS2-2A/2B/2D</italic>. Transcripts of TaGS genes were obtained using the single molecular sequencing technology, and the results showed that <italic>TaGS1;1-6A</italic> had one alternative splicing (AS) version of transcripts and <italic>TaGS1;1-6B</italic> had two AS versions. Compared with the TaGS encoded by normal transcript, TaGS1;1-6A-1 lacked part of the Gln_synt_N domain, and TaGS1;1-6B-3 lacked the Gln_synth_gly_rich_ site domain; <italic>TaGS1;1-6B-4 </italic>was a new AS event, and encoded a truncated GS without Gln_synth_gly_rich_site and Gln_synth_ cat_dom domain. The relative expression level of TaGS alternative splicing transcripts of wheat cultivars with different nitrogen use efficiencies showed that the relative expression level of <italic>TaGS1;1-6A-1 </italic>in leaves of YM49 (N-efficient) was significantly higher than that of XN509 (N-inefficient), and increased with the increase of nitrogen supply. In roots, the relative expression of <italic>TaGS1;1-6A-1</italic> increased with the increase of nitrogen supply in YM49, but decreased in XN509. <italic>TaGS1;1-6B-3</italic> showed a similar expression trend in YM49 and XN509, and high concentration of NO₃^- promoted the expression of <italic>TaGS1;1-6B-3</italic> in leaves while inhibited in roots. High concentration of NH₄⁺ inhibited the expression of <italic>TaGS1;1-6B-3</italic> in leaves, but had little effect in roots. <italic>TaGS1;1-6B-4</italic> was mainly expressed under low nitrogen condition, and its expression in roots of YM49 was not affected by NH₄⁺ supply. Understanding the AS transcript versions of TaGS genes is helpful to illustrate the functions of TaGS isozymes in nitrogen metabolism of wheat.

Winter air quality improvement in Beijing by clean air actions from 2014 to 2018

In order to cope with heavy haze pollution in Beijing, the Air Pollution Prevention and Control Action Plan was issued in 2013. In this study, we took January observations from 2014 to 2018 as a case study to assess wintertime air quality improvement in Beijing after five years of continuous emission control measures and to investigate the causes of haze formation. SO2 and NO2 concentrations in January 2018 decreased by 84% and 41% from January 2014, while NH3 concentrations remained relatively stable during these years with an average of 7.28 μg m−3. The mean concentrations of PM2.5 and water-soluble inorganic ions declined over the study period, while compared with 2014, decreased SO42− ratio and increased NO3− contribution in PM2.5 were observed, highlighting the importance of reactive nitrogen (Nr) pollution control. High concentrations of NH3, NO2, as well as NH4+ and NO3− in PM2.5 at roadside monitoring sites, indicated that vehicle sources played a vital role in local urban Nr emissions. Finally, we found most NH3 existed in the gas phase in the Beijing atmosphere, even on polluted winter days, suggesting a considerable risk for additional secondary aerosol formation. Our findings demonstrate the effectiveness of the emissions control in alleviating Beijing's air pollution. Significant reductions of precursor emissions are needed to achieve the goals set by air quality standards in the future, especially for NH3. It is especially crucial to jointly consider and control multiple pollution sources to effectively reduce the high levels of air pollution that remain in Beijing.

Corrosion of B10 Cu-Ni Alloy in Seawater Polluted by High Concentration of NH4+

Corrosion of B10 Cu-Ni Alloy in Seawater Polluted by High Concentration of NH4+

Synthesis of nitrogenase by Paenibacillus sabinae T27 in presence of high levels of ammonia during anaerobic fermentation.

Biological nitrogen fixation is usually inhibited by fixed nitrogen. Paenibacillus sabinae T27, a Gram-positive, spore-forming diazotroph, possesses high nitrogenase activity and has 3 copies of nifH (nifH, nifH2, nifH3), a copy of nifDK, and multiple nifHDK-like genes. In this study, we found that P. sabinae T27 showed nitrogenase activities not only in low (0-3 mM) concentrations of NH4+ but also in high (30-300 mM) concentrations of NH4+, no matter whether this bacterium was grown in a flask or in a fermenter on scale cultivation. qRT-PCR and western blotting analyses supported that Fe protein and MoFe protein were synthesized under both low (0-3 mM) and high (30-300 mM) concentrations of NH4+. Liquid chromatography-mass spectrometry (LC-MS) analysis revealed that MoFe protein was encoded by nifDK and Fe protein was encoded by both nifH and nifH2. The cross-reaction suggested the purified Fe and MoFe components from P. sabinae T27 grown in both nitrogen-limited and nitrogen-excess conditions were active. This is the first time to report that diazotrophs show nitrogenase activity in presence of high (30-300 mM) concentrations of NH4+. Our study will provide a clue for studying the mechanisms of nitrogen fixation in presence of the high concentration of NH4+. KEY POINTS: • P. sabinae T27 can synthesize active nitrogenase in presence of high levels of ammonia. •Fe and MoFe proteins of nitrogenase purified in absence of ammonia are the same as those purified from the high concentration of ammonia. • Fe protein is encoded by nifH and nifH2, and MoFe protein is encoded by nifDK.

Effects of a Partially Perforated Flooring System on Ammonia Emissions in Broiler Housing-Conflict of Objectives between Animal Welfare and Environment?

Simple SummaryPrevious studies have shown positive effects of a partially perforated flooring system on animal welfare in broiler housing. Towards the end of the fattening periods, the present study showed a higher ammonia emission rate (NH3 ER) for a partially perforated flooring system compared with a littered control barn. Nevertheless, the measured NH3 concentrations were below 20 ppm, except during a mechanical litter treatment in the winter fattening period. Furthermore, the system offers the possibility of applying practical solutions that were not feasible before. By using underfloor air extraction, manure belts, or acidification systems underneath the elevated perforated area, NH3 concentrations and the resulting NH3 ER could be reduced. Thus, with some optimization, the partially perforated flooring system could be used to contribute to an increase in animal welfare and environmental protection at the same time.A partially (50%) perforated flooring system showed positive effects on health- and behavior-based welfare indicators without affecting production performance. Ammonia (NH3) is the most common air pollutant in poultry production, with effects on animal welfare and the environment. The objectives of animal welfare and environmental protection are often incompatible. Therefore, this study addresses the question of how a partially perforated flooring system affects NH3 emissions. According to German regulations, three fattening periods were carried out with 500 Ross 308 broilers per barn (final stocking density: 39 kg m−2). The experimental barn was equipped with an elevated perforated area in the supply section, accessible by perforated ramps. The remaining area in the experimental barn and the control barn were equipped with wood shavings (600 g m−2). Besides the different floor types, management was identical. Air temperature (Temp), relative air humidity (RH), NH3 concentration, and ventilation rate (VR) were measured continuously. Furthermore, dry matter (DM) content, pH, and litter quality were assessed. Towards the end of the fattening periods, the NH3 emission rate (ER) of the partially perforated flooring system was higher compared with that of the littered control barn (all p < 0.001). This effect is mainly caused by the higher NH3 concentrations, which are promoted by the lack of compaction underneath the elevated perforated area and the increase in pH value under aerobic conditions. Nevertheless, the partially perforated flooring system offers different approaches for NH3 reduction that were previously not feasible, potentially contributing equally to animal welfare and environmental protection.

Dissolved organic nutrients at the interface of fresh and marine waters: flow regime changes, biogeochemical cascades and picocyanobacterial blooms—the example of Florida Bay, USA

The availability of dissolved inorganic and organic nutrients and their transformations along the fresh to marine continuum are being modified by various natural and anthropogenic activities and climate-related changes. Subtropical central and eastern Florida Bay, located at the southern end of the Florida peninsula, is classically considered to have inorganic nutrient conditions that are in higher-than-Redfield ratio proportions, and high levels of organic and chemically-reduced forms of nitrogen. However, salinity, pH and nutrients, both organic and inorganic, change with changes in freshwater flows to the bay. Here, using a time series of water quality and physico-chemical conditions from 2009 to 2019, the impacts of distinct changes in managed flow, drought, El Niño-related increases in precipitation, and intensive storms and hurricanes are explored with respect to changes in water quality and resulting ecosystem effects, with a focus on understanding why picocyanobacterial blooms formed when they did. Drought produced hyper-salinity conditions that were associated with a seagrass die-off. Years later, increases in precipitation resulting from intensive storms and a hurricane were associated with high loads of organic nutrients, and declines in pH, likely due to high organic acid input and decaying organic matter, collectively leading to physiologically favorable conditions for growth of the picocyanobacterium, Synechococcus spp. These conditions, including very high concentrations of NH4+, were likely inhibiting for seagrass recovery and for growth of competing phytoplankton or their grazers. Given projected future climate conditions, and anticipated cycles of drought and intensive storms, the likelihood of future seagrass die-offs and picocyanobacterial blooms is high.

Review on carbon dioxide fixation coupled with nutrients removal from wastewater by microalgae

The application of microalgae in carbon dioxide (CO2) fixation coupled with wastewater treatment has been regarded as a promising and cutting-edge technology in recent years, but it still faces some problems. The CO2 fixation capacity and nutrients removal capacity of microalgae should be considered simultaneously under various environmental conditions. Moreover, breeding microalgae using a photobioreactor is required and critical for CO2 fixation and wastewater treatment. In addition, the related influenced factors, mechanisms and kinetics of CO2 fixation and nutrients removal by microalgae remains complex and unclear. Thus, this work provides an updated review of the literature regarding the application of microalgae in the remediation of wastewaters from different sources coupled with CO2 fixation, discusses the main interactions between biological or environmental factors and how they can influence nutrient removal and CO2 fixation efficiencies, and further focuses on their mechanisms and kinetics. It is found that blue-green algae are most suitable to fix CO2 integrating treated wastewater, but more microalgal strains with excellent anti-fouling performance, tolerance to high concentrations of CO2 and NH3–N performance need to be screened. Additionally, wastewater and gas conditions during the cultivation process should be optimized in research and applications, and development of innovative photobioreactors with low cost is also required. Furthermore, modelling mainly focuses on estimating biomass yield, nutrient removal rates and CO2 fixation rates, while laboratory modelling results deviated from the natural modelling results. Finally, this paper also provides insight into what should be done in future work to support the development of CO2 fixation coupled with wastewater treatment by microalgae.

Ongoing anthropogenic eutrophication of the catchment area threatens the Doñana World Heritage Site (South-west Spain)

Eutrophication is a major cause of wetland degradation worldwide. In recent decades, reductions in nutrient inputs have led to improvements in water quality in many rivers and lakes in central and northern Europe, but long-term trends are less clear in southern Europe. We conducted the first comprehensive study of water quality in Doñana (SW Spain), one of the most important wetland complexes in Europe and the Mediterranean region. The core area of Doñana is a large shallow, seasonal marsh (UNESCO World Heritage Site—WHS) that floods during rainy, cool winter months, then dries out during the summer. The marsh is fed by three main streams whose catchments are within a Biosphere Reserve but are impacted by greenhouses (for cultivating fruit, irrigated with groundwater), poorly treated urban wastewaters and tourism. From 2013 to 2016, we monitored nutrient (Total P, Total N, PO4−3, NH4+, NO3−, NO2−) and phytoplankton chlorophyll-a (chla) concentrations in surface waters of the Doñana marsh and the three main streams. We quantified changes in greenhouse cover since 1995 using satellite images. Nutrient concentrations in streams were consistently higher than in the marsh, particularly in the Partido and Rocina streams that regularly reached concentrations equivalent to a “bad physico-chemical status” under the EU Water Framework Directive (WFD), and whose catchments suffered a fivefold expansion of greenhouses from 1995 to 2016. The Partido was the most polluted stream, and the most affected by wastewater effluents, and had particularly high concentrations of NH4+ (Geometric Mean = 0.3 mg L−1) and NO2− (GM = 0.52 mg L−1) across seasons. Patterns in chla concentrations were less consistent, but streams (GM = 6.78 µg L−1) generally had higher concentrations than the marsh (GM = 4.27 µg L−1). Nutrient concentrations in spot samples within the marsh largely depended on a combination of evaporation (as revealed by higher stable isotope δ2H values in the water column) and spatial processes (concentrations increase close to stream entry points, where conductivity is lower). Anthropogenic nutrient pollution in entry streams is a serious problem in Doñana, with extensive stretches too toxic for fish. Reinforcement of policies aimed at reducing nutrient inputs to Doñana are urgently required to meet the biodiversity conservation and environmental objectives for the WHS and WFD, respectively. Paradoxically, the marsh is currently relied upon to purify the water entering from streams.

Aerobic post-treatment of anaerobic digested sludge with a focus on organic matter stability and the fate of antibiotic resistance genes

Abstract Digested residue remains after anaerobic digestion of municipal sludge (hereafter called anaerobic digested sludge, ADS) and needs further treatment to attain more sustainability. In this study, the compostability of ADS was assessed, focusing on the stability of organic matter and the fate of typical antibiotic resistance genes (ARGs). The results showed that ADS was not suitable as a fertilizer (reflected by a low germination index of 16.9%) due to very high concentrations of NH4+ and soluble total organic carbon. Composting post-treatment stabilized the ADS; the degradation efficiency of volatile total solids reached 18.5% within 37 d of composting. The physicochemical properties of the treated ADS indicated that a mature compost product was obtained. Real-time quantitative polymerase chain reaction analysis of typical ARGs revealed that ARG abundance was reduced four-fold during ADS composting due to a reduction in the typical ARGs and low horizontal gene transfer in host microbes. The analysis of bacterial communities revealed that members of the phyla Actinobacteria, Proteobacteria, Firmicutes, Bacteroidetes, and Chloroflexi are crucial for material transformation and ARG reduction during the ADS composting process. These results demonstrated that aerobic composting further stabilized the organic matter and reduced ARG abundance; therefore, it was found to be an effective method for ADS post-treatment.

Ammonia Concentrations and Emissions at Two Commercial Manure-Belt Layer Houses with Mixed Tunnel and Cross Ventilation

HighlightsAnnual average NH3 concentrations in two retrofitted manure-belt layer houses were 4.0 ±3.3 and 5.2 ±3.0 ppmv.Seasonal and diurnal variations were observed for NH3 concentrations (higher in colder seasons and early morning).Annual average NH3 emission rates from the two layer houses were 0.081 ±0.004 and 0.099 ±0.004 g d-1 hen-1.No consistent pattern was found for either seasonal or diurnal variations in NH3 emission rates.Abstract. Ammonia emission measurements at poultry houses are necessary to assess air quality and emission factors associated with poultry operations, but no data have been reported for manure-belt layer houses retrofitted from high-rise layer houses. Two commercial retrofitted manure-belt layer houses (both 121.9 m long, 19.5 m wide, and 7.7 m high; 170,000 bird nominal capacity each) in Ohio with mixed usage of tunnel and cross ventilation systems were continuously monitored for one year. The daily averages of the exhaust NH3 concentrations varied from 0.03 to 17.7 ppmv in house 1 and 0.37 to 14.4 ppmv in house 2 with annual means (±SD) of 4.0 ±3.3 and 5.2 ±3.0 ppmv, respectively. The NH3 emission factors based on the full year of data for houses 1 and 2 were 0.081 ±0.004 and 0.099 ±0.004 g d-1 hen-1 (12.5 ±10.1 and 15.2 ±10.6 kg d-1 house-1 or 24.9 ±20.0 and 31.1 ±23.4 g d-1 AU-1), respectively. Seasonal variations were observed for NH3 concentrations, with higher concentrations in winter and lower concentrations in summer. Within a day, NH3 concentrations were highest from 4:00 to 8:00 and lowest from 16:00 to 20:00. No consistent pattern was observed for seasonal or diurnal variations of NH3 emission rates. Higher NH3 concentrations and emissions were observed at the east and west exhaust air streams of the houses compared to the north and south exhaust air streams due to the unique configuration of the ventilation systems. NH3 emission was correlated with exhaust absolute humidity, hen caloric intake, feed consumption, and protein percentage of feed. Keywords: Ammonia emission factor, Diurnal variation, High-rise, Retrofitted poultry house, Seasonal variation, Spatial variation.

The development and validation of a rapid, in situ method of the determination of NH3 in solid by-products of the combustion process

This article presents the following: the developed apparatus and a rapid, in situ (industrial) method of the determination of NH3 in fly ash and gypsum and the application of the method to real samples. Ammonia is released from the fly ash sample by means of the thermal method in 500–600 °C, using a specially designed 500 W electric tubular furnace. The NH3 is determined by means of a Tunable Diode Laser Spectroscope (TDLS). The range of the method is from 0.18 to 375 μg NH3 and the duration of a single analysis is from 2 to 20 min (depending on the concentration of ammonia in the sample). The constructed system is mobile and it can be used for in situ measurements in industrial conditions. The method can be used both to optimize the operation of DeNOx systems (high NH3 concentration in fly ash) and to measure the level of ammonia in the product (NH3 concentration below 100 mg/kg). The method that was developed has been validated and the uncertainty of the method was estimated in accordance with EURACHM guidelines. The paper describes the use of the developed method to optimize the SCR system operation and reduce ammonia slip in fly ash and flue gas.

Assessing the potential of purple phototrophic microbial community for nitrogen recycling from ammonia-rich medium and anaerobic digestate

Purple phototrophic bacteria (PPB) community, enriched from municipal wastewater, was characterized to assess their growth, tolerance, composition and potential for resource recovery from NH4+-rich medium. Batch experiments were conducted in tissue culture flasks and glass bottles under anaerobic conditions with infra-red lights. PPBs showed remarkable tolerance to high concentrations of NH4+-N and acetate. Below 1.5 g/L, growth was unaffected by NH4+-N with optical density at 590 nm (OD590) reaching 2.6–2.9, while they could tolerate 4.5 g/L NH4+-N. Similarly, PPB growth was unaffected at acetate concentrations below 4 g/L and they could tolerate >20 g/L acetate. Taxonomic characterization showed that the community comprised of 37–52% PPBs (with 15–20% proteins) under different conditions, with Rhodobacter sp. over Rhodopseudomonas sp. dominating at higher NH4+-N concentrations. PPBs showed growth and removal rates in anaerobic digestate and accumulated 26% proteins. These results indicated the potential of PPBs in resource recovery from NH4+-rich wastewater.

PTEN/AKT/mTOR pathway involvement in autophagy, mediated by miR-99a-3p and energy metabolism in ammonia-exposed chicken bursal lymphocytes

Emission of atmospheric ammonia (NH3) is an environmental challenge because of its harmful effects on humans and animals including birds. Among all organisms, NH3 is highly sensitive to birds. Autophagy plays a critical role in Bursa of fabricius (BF)-mediated immune responses against various hazardous substances. Therefore, we designed our work to demonstrate whether NH3 can induce autophagy in broiler chicken BF. In this study, the downregulated levels of mammalian target of rapamycin and light chain-3 (LC-Ⅰ), as well as the upregulated levels of phosphate and tensin homology (PTEN), protein kinase B (AKT), autophagy related-5, light chain-3 (LC3-Ⅱ), Becline-1, and Dynein, were found. Our results of transmission electron microscopy displayed signs of autophagosomes/autophagic lysosomes, and immunofluorescence assay displayed that NH3 exposure reduced the relative amount of CD8+ B-lymphocyte in chicken BF. Exposure of NH3 led to energy metabolism disturbance by decreasing mRNA levels of glucose metabolism factors aconitase-2, hexokinase-1, hexokinase-2, lactate dehydrogenase-A, lactate dehydrogenase-B, pyruvate kinase, phosphofructokinase and succinate dehydrogenase complex unit-B, and adenosine triphosphates (ATPase) activities (Na+/K+ ATPase, Ca2+ ATPase, Mg2+ ATPase, and Ca/Mg2+ ATPase). Moreover, phosphate and tensin homology was found as target gene of microRNA-99a-3p which confirmed that high concentration of NH3 caused autophagy in chicken BF. In summary, these findings suggested that ammonia induced autophagy via miR-99a-3p, the reduction of ATPase activity, and the alteration of autophagy-related factors, and energy metabolism mediation in BF. Our findings provide information to assess the harmful effects of NH3 on chicken and clues for human health pathophysiology.

Atmospheric Ammonia in Beijing during the COVID-19 Outbreak: Concentrations, Sources, and Implications.

This study investigates the concentrations and δ15N values of NH3 in Beijing during and after the 2020 COVID-19 lockdown. Higher NH3 concentrations and lower δ15N-NH3(measured) were observed at most sites in 2020 compared to 2017. Except for a site inside a tunnel, NH3 concentrations did not increase significantly after the lockdown had ended compared to those during the lockdown, while δ15N-NH3(measured) increased by 2.1–9.9‰. Nonagricultural sources (fossil fuel and urban waste) overall contributed 81% and 62% of NH3 at on-road (tunnel interior) and nonroad (CAU) sites in 2020, respectively, comparable to those in 2017 (without significant difference). The contribution of nonagricultural sources slightly increased after the lockdown compared to the contribution during the lockdown at the nonroad site and hardly changed at the tunnel interior site. Our results suggest that (1) unfavorable meteorological conditions, especially lower boundary layer heights and changes in regional transport patterns, might play a more important role than reduced anthropogenic emissions in the temporal variations of Beijing NH3 and (2) the effect of reduced anthropogenic emissions, during the COVID-19 outbreak or with the future implementation of emission control strategies, on atmospheric NH3 can be better demonstrated by isotope-based source apportionment of NH3, rather than only by changes in NH3 concentrations.

Measurement report: Short-term variation in ammonia concentrations in an urban area increased by mist evaporation and emissions from a forest canopy with bird droppings

Abstract. Local meteorological conditions and natural and anthropogenic sources affect atmospheric NH3 concentrations in urban areas. To investigate potential sources and processes of NH3 variation in urban areas, hourly NH3 and NH4+ concentrations were measured during November 2017–October 2019 in Nagoya, a central Japanese megacity. Average NH3 concentrations are high in summer and low in winter. Daily minimum NH3 concentrations are linearly correlated with daily minimum air temperatures. By contrast, daily maximum NH3 concentrations increase exponentially with temperature, suggesting that different nighttime and daytime processes and air temperatures affect concentrations. Short-term increases in NH3 concentrations of two types were examined closely. Infrequent but large increases (11 parts per billion (ppb) for 2 h) occurred after mist evaporation during daytime. During 2 years of observations, only one event of this magnitude was identified in Nagoya, although evaporation of mist and fog occurs frequently after rains. Also, short-term increases occur with a large morning peak in summer. Amplitudes of diurnal variation in NH3 concentration (daily maximum minus minimum) were analyzed on days with nonwet and low wind conditions. Amplitudes were small (ca. 2 ppb) in winter, but they increased from early summer along with new leaf growth. Amplitudes peaked in summer (ca. 20 ppb) because of droppings from hundreds of crows before roosting in trees on the campus. High daily maximum NH3 concentrations were characterized by a rapid increase occurring 2–4 h after local sunrise. In summer, peak NH3 concentrations at around 08:00 local time (LT) in sunny weather were greater than in cloudy weather, suggesting that direct sunlight particularly boosts the morning peak. Daily and seasonal findings related to the morning peak imply that stomatal emission at the site causes the increase. Differences between daily amplitudes during the two summers was explained by the different input amounts of reactive nitrogen from bird droppings and rain, suggesting that bird droppings, a temporary rich source of NH3, affected the small forest canopy.

Arabidopsis thaliana transcription factors MYB28 and MYB29 shape ammonium stress responses by regulating Fe homeostasis.

Although ammonium (NH4+ ) is a key intermediate of plant nitrogen metabolism, high concentrations of NH4+ in the soil provoke physiological disorders that lead to the development of stress symptoms. Ammonium nutrition was shown to induce the accumulation of glucosinolates (GSLs) in leaves of different Brassicaceae species. To further understand the link between ammonium nutrition and GSLs, we analysed the ammonium stress response of Arabidopsis mutants impaired in GSL metabolic pathway. We showed that the MYB28 and MYB29 double mutant (myb28myb29), which is almost deprived of aliphatic GSLs, is highly hypersensitive to ammonium nutrition. Moreover, we evidenced that the stress symptoms developed were not a consequence of the lack of aliphatic GSLs. Transcriptomic analysis highlighted the induction of an iron (Fe) deficiency response in myb28myb29 under ammonium nutrition. Consistently, ammonium-grown myb28myb29 plants showed altered Fe accumulation and homeostasis. Interestingly, we showed overall that growing Arabidopsis with increased Fe availability relieved ammonium stress symptoms and that this was associated with MYB28 and MYB29 expression. Taken together, our data indicated that the control of Fe homeostasis was crucial for the Arabidopsis response to ammonium nutrition and evidenced that MYB28 and MYB29 play a role in this control.