Increase In NH3 Emissions Research Articles

NH3 emission responses to irrigation time and the initial moisture from urea applied to three soils in the North China Plain*

AbstractWater management affects NH3 emission in complex ways due to its influence on nitrogen transformation and movement. This study aimed to determine the effect of irrigation timing on NH3 emission from urea at different initial moistures. A pot experiment was conducted based on three typical soils (Fluvisols, Cambisols, and Luvisols) in the North China Plain. Each soil was treated to three levels of initial moisture (5%, 10%, and 15% w/w) and irrigated with 40 mm water 0, 6, and 12 hr after applying urea. The results showed that NH3 loss ranged from 0.2 to 14.2 kg N ha−1, with the greatest loss in Fluvisols, followed by Cambisols, and the lowest in Luvisols. The loss of NH3 increased with initial moisture for all three soils. But there was no significant effect of irrigation time on NH3 emission, although the contents of NH4+ in surface soil were higher for delayed irrigation than for immediate irrigation. Additionally, the NO3− content was increased in Luvisols with delayed irrigation at a high initial water content, which may have promoted leaching. Therefore, delaying irrigation by up to 12 hr did not cause a significant increase in NH3 emission. However, fertilization and irrigation should be carried out with lower moisture, especially for Luvisols to prevent ammonia emission or nitrate leaching.

Impact of manure compost amendments on NH3 volatilization in rice paddy ecosystems during cultivation

Livestock manure has been widely used in agriculture to improve soil productivity and quality. However, intensive application can significantly enhance soil nitrogen (N) availability and facilitate ammonia (NH3) volatilization during rice cultivation. The effects of different rates of manure application on the NH3 volatilization rate, its mechanism, and their relationships have not been comprehensively investigated. In this study, field trials were conducted to investigate NH3 volatilization in rice paddy soils amended with different livestock manure, cattle manure (CM), and swine manure (SM), at a rate of 0 (NPK), 10, 20, and 40 Mg ha−1 during cultivation. Moreover, the soil physicochemical and biological properties and rice N uptake were investigated. Ultra-fine particulate matter (PM2.5) was measured quantitatively and qualitatively. Manure application significantly increased NH3 emissions compared to the control. Much higher volatilization rates were observed in the SM soils than in the CM soils, even when the same amount of N was applied. This is mainly related to the higher labile NH4+ concentration and urease activity in SM soils. With increasing application levels, NH3 emission rates proportionally increased in the SM, but there was no significant difference in the CM. Livestock manure application significantly increased NH3 volatilization, particularly during the initial manure application and additional fertilization stages during rice cultivation. The results showed that the application of livestock manure significantly increased NH3 volatilization. Moreover, the biochemical properties of manure composts, including labile N and urease activity, mainly affected NH3 dynamics in rice paddies during cultivation rather than their type. Irrespective of manure application, PM2.5, did not show a significant difference at the initial stage of cultivation. NH3 volatilization was not significantly correlated with the formation of PM2.5. It is necessary to develop effective strategies for mitigating NH3 volatilization and maintaining soil quality without decreasing rice productivity in paddy ecosystems.

Manure Flushing vs. Scraping in Dairy Freestall Lanes Reduces Gaseous Emissions

The objective of the present study was to mitigate ammonia (NH3), greenhouse gases (GHGs), and other air pollutants from lactating dairy cattle waste using different freestall management techniques. For the present study, cows were housed in an environmental chamber from which waste was removed by either flushing or scraping at two different frequencies. The four treatments used were (1) flushing three times a day (F3), (2) flushing six times a day (F6), (3) scraping three times a day (S3), and (4) scraping six times a day (S6). Flushing freestall lanes to remove manure while cows are out of the barn during milking is an industry standard in California. Gas emissions were measured with a mobile agricultural air quality lab connected to the environmental chamber. Ammonia and hydrogen sulfide (H2S) emissions were decreased (p < 0.001 and p < 0.05) in the flushing vs. scraping treatments, respectively. Scraping increased NH3 emissions by 175 and 152% for S3 and S6, respectively vs. F3. Ethanol (EtOH) emissions were increased (p < 0.001) when the frequency of either scraping or flushing was increased from 3 to 6 times but were similar between scraping and flushing treatments. Methane emissions for the F3 vs. other treatments, were decreased (p < 0.001). Removal of dairy manure by scraping has the potential to increase gaseous emissions such as NH3 and GHGs.

Optimizing the application of dairy farm effluent and manure to mitigate gas emission

The impact of dairy farm effluent and manure applications upon gas emissions from soil is of concern for agronomic, ecological, and environmental reasons. Yet it remains unclear how the optimized manure and effluent additions may affect gas (nitrous oxide (N2O), nitric oxide (NO), and ammonia (NH3)) emissions during wheat cultivation. We conducted a field experiment in Zhuzhen (Jiangsu), China, from November 2018 to May 2019 to examine the effects of effluent and manure on gas emissions from the wheat fields that had seven treatments (4 replicates, 28 plots): no fertilizer (control); inorganic fertilizer at a conventional application rate of 200 kg N ha−1 (NPK); 100 kg N ha−1 inorganic fertilizer plus 100 (DE1), 150 (DE2), and 250 (DE3) kg N ha−1 farm dairy effluent; 100 kg N ha−1 inorganic fertilizer plus 100 kg N ha−1 farm dairy manure (SM1); and 150 kg N ha−1 inorganic fertilizer plus 50 kg N ha−1 farm dairy manure (SM2). Applying dairy effluent during the wheat season significantly (P < 0.05) increased NH3 emissions from 1.83 (NPK) to 3.81 kg N ha−1 (DE1) and 11.4 kg N ha−1 (DE3), probably due to elevated levels of soil NH4+ and pH, with no discernable impact on N2O emissions compared with NPK. The greater application of effluent in the DE3 treatment increased NO emissions significantly by 33.3% relative to NPK. The combined application of manure and urea significantly reduced N2O and NO emissions by 25.2–27.6% and 8.3–45.8%, respectively, but increased NH3 emissions in the SM1 treatment by 73.8%, when compared with NPK. Overall, our results suggest that replacing 25% of the current conventional chemical N application rate with dairy manure could considerably mitigate gas emissions in the wheat season.

The potential effectiveness of four different options to reduce environmental impacts of grazed pastures. A model-based assessment

Pastoral agriculture can have negative environmental impacts. These include greenhouse gas emissions (such as enteric CH4 and soil N2O emissions), NH3 volatilisation, and leaching of nitrogen into waterways. We used a modelling approach to assess the effect of three plant traits and one management practice on N2O emissions, nitrogen (N) losses via leaching and NH3 volatilisation, pasture production and soil organic carbon (SOC) changes (as applicable). The aim was to identify traits/management practices that could potentially be environmentally beneficial and could then inform future research to find or breed plants with those traits.The traits and practice investigated were: 1) N content in animal feed; 2) plant-excreted nitrification inhibitors; 3) deep rooting; and 4) frequency of pasture renewal. Of these, the N content in animal feed provided the most promising results, with low N content resulting in lower urine N excretion, and consequently reduced leaching losses and emissions of N2O and NH3. Modelling the effect of plant-excreted nitrification inhibitors showed mixed results, with reduced leaching rates but increased NH3 emissions. N2O emissions could be reduced if nitrification rates were strongly reduced. However, at lower rates of inhibition, there was little effect on N2O emissions. In the deep rooting scenarios, we found that N leaching losses were minimised if roots grew predominantly in upper soil layers where any mineral N was likely to spend more time before being leached. Nitrogen was, therefore, more effectively intercepted and prevented from leaching by greater root proliferation in the upper rather than deeper layers. For pasture renewal, we unexpectedly found that SOC could be increased by more frequent pasture renewal. However, this would come at the cost of reduced pasture production as renewal events reduced grazing off-takes proportionately more than the reduction in carbon gain by pasture plants. A renewal period of about 10 years was found to be optimal for pasture production and could be maintained with minimal SOC changes.

Ammonia emission from manures treated with different rates of urease and nitrification inhibitors

Urease inhibitors have been successfully used to reduce ammonia (NH3) emission from urea-based fertilizers. However, studies on its effectiveness with manures have produced inconclusive results. Field and greenhouse studies were conducted to investigate the effectiveness of different rates of urease [N-(n-butyl) thiophosphoric triamide; NBPT] with and without nitrification inhibitor (NI) in reducing NH3 emission from surface-applied liquid pig manure (LPM) and solid beef manure (SBM). Ammonia emission was measured with acid-charged discs at seven dates for 28 d. Total NH3 emission (% of applied N) ranged from 4.3% to 8.2% in untreated LPM and 8.2% in untreated SBM. The corresponding NH3 emission was 6.8%–7.4% in LPM treated with NBPT, 5.0%–12.3% in LPM treated with NBPT + NI (double inhibitor; DI), and 6.0%–10.8% in SBM treated with DI. In the field study, NH3 emission was not significantly different between either LPM or SBM treated with and without DI. In the greenhouse, NBPT did not significantly reduce NH3 emission from LPM, whereas DI applied at a lower rate significantly increased NH3 emission from LPM. In conclusion, addition of NBPT to manure did not have any significant environmental benefit, whereas a combination of NBPT and NI increased NH3 emission from manure.

Effects of boric acid on urea-N transformation and 3,4-dimethylpyrazole phosphate efficiency.

3,4-Dimethylpyrazole phosphate (DMPP) is a nitrification inhibitor which can restrict nitrate (NO3 - ) production. Boric acid is a substance which inhibits urease activity. However, few studies have focused on the inhibitory effect of boric acid on urea hydrolysis and the possible synergistic effect with DMPP. Thus, an incubation trial was conducted to determine the impact of boric acid and DMPP addition on urea-N transformation, and their synergistic effects, in chernozem soil (Che) and red soil (RS). Four treatments were set up in each soil: urea only (U); urea combined with DMPP (UD); urea combined with boric acid (UB); and urea combined with both DMPP and boric acid (UDB). Compared to U, adding DMPP (UD) increased NH3 emissions by 11% and 13% and decreased soil NO3 - -N concentration by 38% and 13% in Che and RS, respectively. Boric acid addition (UB) effectively prolonged the half-life time of urea by 0.8 and 0.4 days, reduced NH3 volatilizations by 11% and 16% and delayed the occurrence of NH3 emission peaks for 3 and 4 days in contrast to U treatment in Che and RS, respectively. UDB treatment mitigated the NH3 volatilizations caused by the addition of DMPP (UD) by 16% and 29% in Che and RS, respectively. Additionally, a better nitrification inhibition rate was found in the UDB treatment compared to other treatments in both soils. There is potential to develop a new N transformation inhibition strategy with the use of a combination of boric acid and DMPP. © 2020 Society of Chemical Industry.

Spatial and temporal variations of atmospheric chemical condition in the Southeastern U.S.

Animal feeding operations (AFOs) are the largest ammonia (NH3) emission sources in the United States (U.S.). However, the impact of NH3 emissions from AFOs on the formation of secondary inorganic PM2.5 (iPM2.5) has not been well understood and systematically assessed. Under the Southeastern Aerosol Research and Characterization (SEARCH) Network, the hourly concentrations of iPM2.5 chemical compositions and its precursor gases as well as meteorological data were measured at eight urban/nonurban sites labeled as JST/YRK, BHM/CTR, GFP/OAK, and PNS/OLF during 1998–2016. Using the SEARCH data, this research investigated the spatiotemporal variations of atmospheric chemical conditions in those rural and urban areas. The spatiotemporal variations of atmospheric chemical conditions at the eight sites are characterized by four parameters, including (1) gas ratio (GR), (2) gas-phase NH3 molar fraction (NH3/NHx), (3) total available NH3 (gaseous ammonia + aerosol ammonium) to sulfate (SO42−) molar ratio (TA/TS), and (4) PM2.5 ammonium + nitrate to total PM2.5 mass ratio (AN/PM2.5). Results indicate that the NH3 emissions from AFOs may explain the greater values of GR, NH3/NHx, and TA/TS in the wind directions coming from AFOs at YRK and OAK rural sites than the other wind directions. In the wind directions coming from AFOs at YRK and OAK, NH3 was in excess of fully neutralizing acidic gases, more NH3 stayed in gas phase than those in other wind directions, and both ammonium sulfate and ammonium nitrate existed in iPM2.5. The upward trend in NH3/NHx indicates that gas-particle partitioning ofNH3–NH4+shifted toward gas phase, while the downward trend in AN/PM2.5 may implicate that smaller fraction of PM2.5 was directly NH3 sensitive. Understanding of the spatiotemporal variations of atmospheric chemical condition provides insights to improve our understanding of iPM2.5 formation under rural and urban conditions, the reduction in sulfur dioxide (SO2) and nitrogen oxides (NOx) emissions resulted in the reduction of iPM2.5 formation despite the increase in NH3 emissions in the Southeastern U.S.

Modelling nitrification inhibitor effects on N&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;O emissions after fall- and spring-applied slurry by reducing nitrifier NH&amp;lt;sub&amp;gt;4&amp;lt;/sub&amp;gt;&amp;lt;sup&amp;gt;+&amp;lt;/sup&amp;gt; oxidation rate

Abstract. Reductions in N2O emissions from nitrification inhibitors (NI) are substantial but remain uncertain because measurements of N2O emissions are highly variable and discontinuous. Mathematical modelling may offer an opportunity to estimate these reductions if the processes causing variability in N2O emissions can be accurately simulated. In this study, the effect of NI was simulated with a simple, time-dependent algorithm to slow NH4+ oxidation in the ecosystem model ecosys. Slower nitrification modelled with NI caused increases in soil NH4+ concentrations and reductions in soil NO3- concentrations and in N2O fluxes that were consistent with those measured following fall and spring applications of slurry over 2 years from 2014 to 2016. The model was then used to estimate direct and indirect effects of NI on seasonal and annual emissions. After spring slurry applications, NI reduced N2O emissions modelled and measured during the drier spring of 2015 (35 % and 45 %) less than during the wetter spring of 2016 (53 % and 72 %). After fall slurry applications, NI reduced modelled N2O emissions by 58 % and 56 % during late fall in 2014 and 2015 and by 8 % and 33 % during subsequent spring thaw in 2015 and 2016. Modelled reductions were consistent with those from meta-analyses of other NI studies. Simulated NI activity declined over time so that reductions in N2O emissions modelled with NI at an annual timescale were relatively smaller than those during emission events. These reductions were accompanied by increases in NH3 emissions and reductions in NO3- losses with NI that caused changes in indirect N2O emissions. With further parameter evaluation, the addition of this algorithm for NI to ecosys may allow emission factors for different NI products to be derived from annual N2O emissions modelled under diverse site, soil, land use and weather.

Nitrogen stabilizers mitigate reactive N and greenhouse gas emissions from an arable soil in North China Plain: Field and laboratory investigation

Nitrogen (N) stabilizers such as urease inhibitors (UI) and nitrification inhibitors (NI) are promising tools to mitigate N losses from fertilized soils. To better understand the efficacy of UI and NI, a 2-year field trial was carried out in the North China Plain (NCP) to analyze the impact of UI and NI on NH3 loss and N transformations following urea fertilizer application. Additionally, a laboratory study using an automated continuous-flow incubation system was conducted under controlled conditions, using the same soil, to evaluate the mitigation potential of the N stabilizers on NO, N2O and CO2 emission. The results showed that a novel UI product, Limus® (BASF, Germany), containing active ingredients N-(n-butyl) thiophosphoric triamide (NBPT) and N-(n-propyl) thiophosphoric triamide (NPPT), limited ammonium formation rate and reduced NH3 loss in both maize (by 85 and 96% for year 1 and 2, respectively) and wheat (by 41 and 64%, for year 1 and 2, respectively) seasons. The 3, 4-dimethypyrazole phosphate (DMPP) amendment significantly retarded nitrate formation rate but the effectiveness was compromised by high ambient temperature; additionally, the NI amendment increased NH3 emission (by 16 and 24% for maize and wheat year 2, respectively). In the laboratory incubation experiment, addition of the UI reduced emissions of NO, N2O and CO2 by 89, 73 and 19%, respectively, while the addition of the NI reduced the respective emissions by 95, 83 and 24% over the 16 d incubation period. These results suggest that N stabilizers can play a significant role in the mitigation of the environmental impacts of intensive agriculture, and, in particular, that the UI amendment may have the better potential to reduce N losses in the climatic and soil conditions of the NCP, and that the NI should be avoided under high ambient temperatures.

Spatio-temporal distribution of ammonia (NH3) emissions in agricultural fields across North China.

Ammonia (NH3) is one of the main polluted gases in the atmosphere, and its emission has markedly increased in recent years. In China, NH3 is mainly emitted from agricultural fields. Using city-wide data on NH3 emissions in agricultural fields, the spatio-temporal emission of NH3 was estimated for North China. This included emissions from nitrogen fertilizers, field straws, background soil, nitrogen-fixing plants, human feces, and livestock/poultry manure. Based on the results, the range of NH3 emission in agricultural lands was 1623.0-1801.5Gg/year. The rate of increase in NH3 emission in the period 2003-2015 was 0.74% per year, which was relatively stable. The leading sources of NH3 emission included the excessive use of chemical fertilizers in agriculture and the continuous expansion of livestock and poultry industries scale, accounting respectively for 44.9% and 43.9% NH3 emission in the study area, respectively. Hebei and Shandong provinces contributed the highest NH3 emission in North China. The contribution rate of NH3 emission in each province varied with sources, agricultural development, and population density. Based on the 1km × 1km grid resolution map for NH3 emission, the range and average of emission were 9.72-10.13kg/ha and 9.95kg/ha, respectively. High emissions were in the southeast of Hebei province and most of Shandong province. For these regions, there is a need for changes in policies relating to the use of chemical fertilizers in agriculture and the management methods of livestock production in the region.

Linseed and glycerol in forage diets effect methane production and rumen fermentation parameters in a Rusitec semi-continuos system

Context The use of oilseeds as a feed ingredient has been proposed to improve fatty acid profiles and reduce methane (CH4) emissions. Glycerol has been used as a common additive in ruminant feeding systems with variable effects on CH4 production. The effects of the combination of these ingredients remain unknown. Aims The aim of this study was to assess the effects of feeding linseed and increasing concentrations of glycerol in forage diets supplemented with corn grain on nutrient disappearance, CH4 production and rumen fermentation parameters. Methods Experimental diets were: control (70:30% hay:corn); linseed (70:15 :15% hay:corn:linseed); 5% glycerol (70:10:15:5% hay:corn:linseed:glycerol); 10% glycerol (70:5:15:10% hay:corn:linseed:glycerol). Diets were incubated in a completely randomised design with four replicates per treatment in a Rusitec apparatus for 15 days (10 days adaptation, 5 days sampling). Key results Total VFA production (VFA, mmol/day) was quadratically increased due to glycerol concentration in the diets (P = 0.009). Acetate:propionate (A:P) decreased by the inclusion of linseed (P &amp;lt; 0.001) and glycerol into the diets (P &amp;lt; 0.001). Linseed inclusion in the diet reduced CH4 production, mg/DM disappeared (P = 0.004) by up to 36%. These effects were not altered by the addition of glycerol into the diets. Ammonia nitrogen (NH3-N) production increased 2-fold in the linseed-added diets, but this effect was partially reverted by increasing glycerol concentrations in the diets (P &amp;lt; 0.001). Crude protein (CP) disappearance increased (P &amp;lt; 0.001) in the linseed added diets, with no effect of glycerol addition. Neutral detergent fibre (aNDFom; P = 0.005) disappearance was increased by the addition of linseed to the diet. Conclusions The use of linseed in ruminant diets reduces CH4 emissions but increases NH3-N production in a Rusitec system. This latter effect is partially reverted by glycerol inclusion in the diet. Propionate production increases with the inclusion of glycerol, but does not alter CH4 production. Including linseed increases the in vitro CP disappearance without affecting DM total disappearance. Implications Care should be taken with the use of oilseeds in ruminant diets as it can reduce CH4 emissions but may cause important increases in NH3 emissions. Inclusion of glycerol may partially overcome this latter issue.

Effect of urease and nitrification inhibitors on ammonia volatilization and abundance of N‐cycling genes in an agricultural soil

AbstractThe effect of the combined application of urease and nitrification inhibitors on ammonia volatilization and the abundance of nitrifier and denitrifier communities is largely unknown. Here, in a mesocosm experiment, ammonia volatilization was monitored in an agricultural soil treated with urea and either or both of the urease inhibitor N‐(n‐butyl) thiophosphoric triamide (NBPT) and the nitrification inhibitor 3,4‐dimethylpyrazole phosphate (DMPP), with 50% and 80% water‐filled pore space (WFPS). The effect of the treatments on the abundance of bacteria and archaea was estimated by quantitative PCR (qPCR) amplification of their respective 16S rRNA gene, that of nitrifiers using amoA genes, and that of denitrifiers by qPCR of the norB and nosZI denitrification genes. After application of urea, N losses due to NH3 volatilization accounted for 23.0% and 9.2% at 50% and 80% WFPS, respectively. NBPT reduced NH3 volatilization to 2.0% and 2.4%, whereas DMPP increased N losses by up to 36.8% and 26.0% at 50% and 80% WFPS, respectively. The combined application of NBPT and DMPP also increased NH3 emissions, albeit to a lesser extent than DMPP alone. As compared with unfertilized control soil, both at 50% and 80% WFPS, NBPT strongly affected the abundance of bacteria and archaea, but not that of nitrifiers, and decreased that of denitrifiers at 80% WFPS. Regardless of moisture conditions, treatment with DMPP increased the abundance of denitrifiers. DMPP, both in single and in combined application with NBPT, increased the abundance of nitrification and denitrification genes.

Insight into the effects of sulfamethoxazole and norfloxacin on nitrogen transformation functional genes during swine manure composting

The effects of sulfamethoxazole and norfloxacin on nitrogen functional genes were investigated in four composting treatments of swine manure: CK (no antibiotics), SMZ (spiked with 5 mg kg−1 dry weight (DW) sulfamethoxazole), NOR (spiked with 5 mg kg−1DW norfloxacin), and SN (spiked with 5 mg kg−1DW sulfamethoxazole and 5 mg kg−1DW norfloxacin). Antibiotics decreased relative abundance of bacterial amoA and nxrA, while increased nosZ/nirK. The decline in amoA/16S rRNA increased the total NH3 emission in SMZ and NOR from 1027.05 to 1144.39 and 1278.22 mg kg−1DW. The decrease of nxrA/16S rRNA enhanced the NO2−-N content and N2O emission in SMZ in the initial composting. Additionally, the increase in nosZ/nirK probably was the main reason for the lower N2O emission in SN than other treatments in the cooling phase. The inhibition on nitrification process and increase in NH3 emission resulted from antibiotics is worthy of attention in the future.

Combining deep flooding and slow-release urea to reduce ammonia emission from rice fields

Abstract The high risk of ammonia (NH3) emission from rice fields limits the efficient and cleaner production of rice (Oryza sativa L.). Currently, little is known about the combined effects of irrigation and fertilization on NH3 emission from rice fields. Specially, the contributions of different field factors to NH3 emission and the role of the rice canopy in NH3 emission are not fully understood. This study aimed to (i) determine the best combination of irrigation and fertilization for reducing NH3 emission from rice fields and (ii) elucidate the mechanisms involved based on the data from 17 field factors. A 2-year field experiment (2017 and 2018) was performed consisting of nine treatments: the full combination of three irrigation treatments (deep flooding (DF), moderate flooding (MF), and shallow flooding (SF)) and three fertilization treatments (the control test (N0), urea (U), and slow-release urea (SU)). The results indicated that nitrogen (N) application significantly increased NH3 emission from rice fields (p

Trends in ammonia emissions from light-duty gasoline vehicles in China, 1999–2017

Ammonia (NH3) emitted from motor vehicles is a by-product of measures taken to reduce emissions of other pollutants (e.g. NOx and CO) and has potentially important environmental impacts. NH3 levels can be impacted by various emission standards. However, there is a lack of investigations of the influences from the implementation of different vehicular emission standards on long-term changes in NH3 emissions. To fill this gap, we estimated the inter-annual NH3 emissions of light-duty gasoline vehicles (LDGVs) under different emission standards (State 0 to State V) from 1999 to 2017 and investigated the emission change characteristics under the rapidly developing Chinese economy. Results showed that the NH3 emissions from LDGVs had a sharp, 42-fold increase (from 1.8Gg to 77.9Gg). However, NH3 emissions per capita have begun to decrease with increases in socioeconomic development, presenting an inverted U-shaped tendency as a function of per capita GDP. Further exploration indicated that the decline in emission factors, as determined by upgrades in emission standards, was the decisive factor in promoting the downward trend in per capita emissions. This suggests that continuously upgrading emission standards has offset the increase in NH3 emissions due to the rapid growth of motor vehicles. Quantitative scenario analysis showed a two-stage impact of emission standards on NH3 emissions: emissions would decrease 77% (48%–90% for different years) if State I and State II were not implemented; while if none of standards were upgraded (State III to State V), NH3 emissions would increase 118% (13%–224% for different years), 2–6 times the impacts from the growth of vehicle population and the decline of vehicle kilometres traveled. The data and findings in this study can provide scientific support for understanding air pollution in urban areas and for formulating further vehicle pollution mitigation measures in China and other countries.

Evaluation of Real-World Gaseous Emissions Performance of Selective Catalytic Reduction and Diesel Particulate Filter Bus Retrofits.

This study reports on the results of gaseous pollutants emission measurements of double-decker buses in an urban road network, using portable emission measurement systems (PEMS). Measured vehicles were tested by following in-service buses on regular routes. Six Euro II and Euro III buses were retrofitted with diesel particulate filters (DPF) and selective catalytic reduction (SCR) or a combined SCR+DPF (SCRT) device. Substantial and statistically significant technology impacts were observed for several pollutants. Optimized SCR and SCRT retrofit technology reduced real-world NO x emissions by approximately 70%, on average. Retrofit DPF slightly reduced NO x emissions but increased direct NO2 emissions by more than a factor of 8, on average. SCRT led to about 70% lower NO2 levels than DPF alone, but for some vehicles higher NO2 levels were observed as compared with the "no retrofit" situation, warranting further investigation. None of the SCR systems were found to lead to a substantial increase in NH3 emissions after operation optimization. High NH3 and N2O emissions were occasionally observed while experience with the system calibration was being accumulated. Observed average N2O emission levels for "DPF+SCR" technology were relatively high at 182 mg/kg fuel, corresponding to 1.5% of total greenhouse gas emissions. The study shows that SCR retrofit programs can be effective for NO x reduction of transit buses but that proper calibration and regular emission monitoring are required.

A meta-analysis of environmental factor effects on ammonia emissions from dairy cattle houses

Livestock housing is one of the main sources of ammonia (NH3) emissions from agriculture. Different management and environmental factors are known to affect NH3 emissions from housing systems. The aim of this study was to quantitatively define the effect of temperature, wind speed, relative humidity, and ventilation rate on NH3 release rates from dairy cattle housing by conducting a meta-analysis of published scientific results. A literature survey was performed to review studies published before January 2018 that have identified statistical relationships between NH3 emissions and environmental factors such as air temperature, wind speed, relative humidity, or ventilation rate in dairy cattle housing. Experimental values were related using a mixed model analysis in order to analyse the effect of environmental factors on NH3 emissions. For this exercise, a total of 19 peer-reviewed papers were considered and 27 different relations between air temperature and NH3 emissions were used for the analysis. A significant effect of air temperature inside the barn and ventilation rate on NH3 emissions was observed. Results showed that NH3 emissions increased linearly with increasing air temperature (oC) inside the barn by 1.47 g [NH3] cow−1 d−1 when temperature increased by one degree. For ventilation rate, an increase of 100 m3 h−1 cow−1 led to an increase in NH3 emissions of 0.007 g [NH3] cow−1 d−1. The equations obtained in this work might help to provide information on NH3 barn-related emissions behaviour under these environmental conditions, bearing in mind that other source of emissions such as diet composition and animal performance might be also affected by climate changes.

Effect of changes in management practices and animal performance on ammonia emissions from Canadian beef production in 1981 as compared with 2011

The present study compared ammonia (NH3) emissions from Canadian beef production in 1981–2011. Temporal and regional differences in cattle categories, feed types and management systems, average daily gains, carcass weights, and manure handling practices were considered. A scenario-based sensitivity analysis in 2011 estimated the impact of substituting corn dried distillers’ grains with solubles (DDGS) for grain in feedlot diets. On average, 22% of the total nitrogen (N) intake was lost as ammoniacal nitrogen (NH3-N) in both years. Manure emission sources were consistent across years, averaging 12%, 40%, 28%, and 21% for grazing, confinement, storage, and land spreading, respectively. Emissions per animal in 1981 and 2011 were 16.0 and 18.4 kg NH3 animal−1 yr−1, respectively. On an intensity basis, kilogram of NH3 emitted per kilogram of beef decreased 20%, from 0.17 in 1981 to 0.14 in 2011. This reduction was attributed to increases in reproductive efficiency, average daily gain and carcass weight, and improved breeding herd productivity. In 2011, substituting DDGS for grain in feedlot diets increased total NH3 emissions and losses per animal. Although addition of by-products from the bioethanol industry can lower diet costs, it will be at the expense of an increase in NH3 emissions.

Ammonia emissions from an in-ground finisher hog manure tank

A large fraction of emitted and ultimately deposited ammonia (NH3) originates from swine waste storage. Understanding the factors that influence these emissions is important in determining how to mitigate NH3 loading of the atmosphere. Hog manure is stored in slurry pits, tanks, or lagoons. Ammonia emissions from a ground-level mid-western hog finisher manure tank collecting manure from a mean of 3508 animals was measured for 8–20 d each quarter of the year for two years. Forty of the 164 measurement days had sufficient measurements to represent entire days. These daily emissions averaged 0.44 g NH3 m−2h−1 (53.1 g d−1 AU−1, 7.2 g d−1 hd−1: AU = 500 kg animal mass, hd = 1 animal) with maximum emissions of 1.62 g NH3 m−2h−1 (194.2 g d−1 AU−1, 26.4 g d−1 hd−1). Emissions from the tank were greater on an area basis but comparable on an animal basis relative to emissions from much larger anaerobic lagoons. Emissions were correlated with air temperature and manure composition, but not wind speed or friction velocity- probably due to the turbulence created by the tank structure under all winds. Crusting of the manure surface in the tank corresponded with a non-significant 10% increase in NH3 emissions. A model of the tank emissions, based on nominal nitrogen loading rates from the literature and taking into account the configuration of the circular tank, had a mean bias error of 0.01 g NH3 m−2h−1 (0.9 g d−1 AU−1, 0.1 g d−1 hd−1) and a root mean square error of 0.26 g NH3m−2h−1 (31.6 d−1 AU−1, 4.3 g d−1 hd−1). Additional emissions measurements from such ground-level manure storage tanks with greater documentation of the manure liquid composition are needed to verify the modeling approach.