NH3 Emission Rates Research Articles

Effects of Nano-membrane on Aerobic Composting Process and Odor Emission of Livestock Manure

Aerobic composting is an important approach to treat livestock manure; however, traditional composting has some problems, such as low efficiency, or odorous pollution. In order to speed up the composting process and reduce malodorous gas emissions, this study explored the mechanism of nano-membrane for improving the efficiency of livestock manure composting. A trough aerobic composting experiment was set up to evaluate the physicochemical properties, enzyme activities, and emission of odorous gases. The results showed that covering with nano-membrane could accelerate the temperature rise; reduce the pH, organic matter(OM), and ammonia nitrogen(NH4+-N); increase electrical conductivity(EC); enhance the activities of urease, protease, cellulase, xylanase, and peroxidase; while the total cumulative emissions of NH3, H2S, and TVOC were reduced by 58%, 100%, and 61%, respectively. The correlation analysis showed that most enzyme activities were easily affected by temperature(T), EC, OM, and C/N. The emission rate of NH3 was positively correlated with T and negatively correlated with pH, and TVOC was significantly correlated with various physicochemical properties. This experiment showed that covering nano-membrane could accelerate the compost maturity and reduce the emission of odorous gases. This approach has no health risks and produces low malodorous gas, which may effectively solve the problem of pollutant emission caused by livestock manure compost fermentation, promoting the green and sustainable development of the breeding industry. In addition, it facilitates livestock manure fertilizer application, and provides technical support for the development of resource utilization of biomass waste.

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.

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.

Comparing NH3 emissions under different cattle housing conditions in cold regions in China with an inverse dispersion technique

Accurately assessing ammonia (NH3) emissions from animal farms is necessary for determining the effectiveness of various mitigation practices to minimize related environmental risks and maximize the potential of recycling nitrogen from manure. This study attempted to validate a hypothesis formulated using a mass-flow inventory model, which suggested that "Barn only" housing facilities without open lots might have a lower NH3 loss potential than "Barn+Lot" facilities with both dairy barns and open lots. NH3 emissions from two "Barn+Lot" dairy farms and one "Barn only" dairy farm were measured using a combination of an inverse dispersion modeling technique and an open-path laser in summer and winter. It was found that the uncertainty of emission estimates owing to the spatial variation of animal densities in the three dairy farms was 8–12%, and the total uncertainty of the NH3 emission estimates owing to spatial variation in animal densities, distortion of wind flow by animal buildings, and the inverse dispersion calculation was estimated to be less than 30%. The NH3 emission rates obtained from the "Barn only" farm (28–43 g head−1d − 1) were lower than the rates from the conventional "Barn+Lot" farms (93–184 g head−1d − 1), indicating emission mitigation of 71–76%. In comparison with the conventional dairy farms, the "Barn only" dairy farm had a lower NH3 loss potential, most likely due to the greater animal density, frequent manure removal, and lower crude protein feed. However, more field measurements of such comparisons are necessary to provide robust suggestions for mitigating environmental risks.

Assessment of the Relationship between Degradation and Emission Activities of Carbon Capture Amines Based on their Chemical Structures

In this work, 16 alkanolamines were investigated to determine the effect of their chemical structural positioning of different functional groups on the rates of amine degradation and ammonia (NH3) emissions as well as to determine if there were inter-relationships between degradation and emission based on their structures. The oxidative degradation and emission experiments were carried out continuously for 2 weeks at the temperature of 60 C using 99.5% O2 gas set at a flow rate of 200±2 mL/min. The amine degradation rate was determined by evaluating the rate of decrease of the amine concentration with time. The NH3 emissions was investigated by collecting the NH3 released from the amine solution in an impinger system set up in accordance with the relevant EPA method. The effect of the alkyl chain length in between amino and hydroxyl groups was investigated by considering groups of primary and tertiary alkanolamines. The degradation rate was observed to decrease with increasing alkyl chain length which helped to strengthen the N-C bond due to the electron donating properties of the alkyl group. The degradation rate was found to decrease in the order: MEA  3A1P > 5A1P and DMAE > 3DMA1P > 4DMA1B for primary and tertiary alkanolamines, respectively. In contrast however, the opposite trend was observed for NH3 emissions in the two amine groups. In the case of end alkyl chain length of secondary alkyl-alkanolamines, it was observed that a longer chain length led to a decrease in the degradation and NH3 emission rates. Their order was: MAE  EAE > BAE. The longer chain length of end alkyl group contributed to both electronic and steric hindrance effects that increase the stability of N-C bond which reduced the formation free radicals thereby decreasing the degradation and NH3 emission rates. For tertiary alkyl-alkanolamines, the degradation rate noticeably decreased in the order of MDEA > EDEA > BDEA. The reasons are similar to those previously given for the same group in secondary alkyl-alkanolamine. NH3 emission rates obtained by this amine group was extremely low with the actual trend unable to be clearly determined. The presence of hydroxyl group known as an electron withdrawing group enhanced the degradation rate as a result its ability to weaken the N-C bond. This facilitated the occurrence of amine degradation. This trend was obtained for secondary alkanolamines (less steric effect) whose degradation and NH3 emission rates of DEA containing two hydroxyl groups were higher than those for EAE containing one hydroxyl group. Steric hindrance effect derived from the presence of the hydroxyl group was also there specifically for tertiary alkanolamines and sterically hindered primary amines comparisons. Having more hydroxyl group in the amine molecule will enhance the oxidative degradation reaction, but at the same time, will promote the steric hindrance effect. The latter effect is more dominant, and thus, increased hydroxyl group number has the net effect of obstructing the occurrence of oxidative degradation reaction thereby resulting in the decrease of the degradation rate. On the other hand, we did not observe any significant difference in NH3 emission rate from tertiary and sterically hindered primary amines due to slow rate of degradation as a result of the steric effect introduced by their structure. Since the net degradation rate decreased with increasing number of hydroxyl groups, it can be concluded that the steric hindrance effect is more dominant in the rate of amine degradation and NH3 emission than the electronic effect.

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.

Quantification and source characterization of volatile organic compounds from exercising and application of chlorine‐based cleaning products in a university athletic center

Humans spend approximately 90% of their time indoors, impacting their own air quality through occupancy and activities. Human VOC emissions indoors from exercise are still relatively uncertain, and questions remain about emissions from chlorine-based cleaners. To investigate these and other issues, the ATHLETic center study of Indoor Chemistry (ATHLETIC) campaign was conducted in the weight room of the Dal Ward Athletic Center at the University of Colorado Boulder. Using a Vocus Proton-Transfer-Reaction Time-of-Flight Mass Spectrometer (Vocus PTR-TOF), an Aerodyne Gas Chromatograph (GC), an Iodide-Chemical Ionization Time-of-Flight Mass Spectrometer (I-CIMS), and Picarro cavity ringdown spectrometers, we alternated measurements between the weight room and supply air, allowing for determination of VOC, NH3 , H2 O, and CO2 emission rates per person (emission factors). Human-derived emission factors were higher than previous studies of measuring indoor air quality in rooms with individuals at rest and correlated with increased CO2 emission factors. Emission factors from personal care products (PCPs) were consistent with previous studies and typically decreased throughout the day. In addition, N-chloraldimines were observed in the gas phase after the exercise equipment was cleaned with a dichlor solution. The chloraldimines likely originated from reactions of free amino acids with HOCl on gym surfaces.

Ammonia emissions from different pig production scales and their temporal variations in the North China Plain

ABSTRACT Pig production systems in China are shifting from small to industrial scale. Significant variation in housing ammonia (NH3) emissions can exist due to differences in diet, housing design, and management practices. However, there is a knowledge gap regarding the impacts of farm-scale in China, which may be critical in identifying hotspots and mitigation targets. Here, continuous in-situ NH3 concentration measurements were made at pig farms of different scales for sows and fattening pigs over periods of 3–6 days during two different seasons (summer vs. winter). For the sow farms, NH3 emission rates were greater at the small farm (summer: 0.52 g pig−1 hr−1; winter: 0.21 g pig−1 hr−1) than at the large farm (summer: 0.34 g pig−1 hr−1; winter: 0.12 g pig−1 hr−1). For the fattening pig farms, NH3 emission rates were greater at the large farm (summer: 0.22 g pig−1 hr−1; winter: 0.16 g pig−1 hr−1) than at the small farm (summer: 0.19 g pig−1 hr−1; winter: 0.07 g pig−1 hr−1). Regardless of farm scale, the NH3 emission rates measured in summer were greater than those in winter; the NH3 emission rates were greater in the daytime than at the nighttime; a positive relationship (R2 = 0.06–0.68) was established between temperature and NH3 emission rate, whereas a negative relationship (R2 = 0.10–0.47) was found between relative humidity and NH3 emission rate. The effect of farm-scale on indoor NH3 concentration could mostly be explained by the differences in ventilation rates between farms. The diurnal variation in NH3 concentration could be partly explained by ventilation rate (R2 = 0.48–0.78) in the small traditional farms and by emission rate (R2 = 0.26–0.85) in the large industrial farms, except for the large fattening pig farm in summer. Overall, mitigation of NH3 emissions from sow farms should be a top priority in the North China Plain. Implications: The present study firstly examined the farm-scale effect of ammonia emissions in the North China Plain. Of all farms, the sow farm was identified as the greatest source of ammonia emission. Regardless of farm scale, ammonia emission rates were observed to be higher in summer. Ammonia concentrations were mostly higher in the large industrial farms partly due to lower ventilation rates than in the small traditional farms.

Influence of biological pretreatment of poultry manure on biochemical methane potential and ammonia emission

Poultry manure has great potential for renewable energy utilization in biogas production. However, extremely high levels of nitrogen lead to unstable conditions in the anaerobic process, including the accumulation of intermediates, such as ammonia, which reduces the biogas production and the quality of the biogas. For this reason, additional measures are needed to ensure the proper management of poultry manure in anaerobic systems. This study evaluated the effect of primary biological treatment of poultry manure on biochemical methane potential (CH4) and reduction of ammonia (NH3) emissions. The results obtained when evaluating the biochemical methane potential from the digestate revealed that the biological additives selected for the study did not significantly influence the biochemical methane potential. After considering the differences of dry organic matter, it was found that maintaining optimum conditions and using biological additives during pretreatment increases the biochemical methane potential from 11.00 to 89.94 L CH4/kg volatile solids (VS). Biological pretreatment of poultry manure has a positive effect on biogas composition: methane concentration increases by 6.3–10.4% after pretreatment, and impurities such as hydrogen sulphide (H2S) decrease by 1.1–17.4 times. Ammonia emissions from all treatments of poultry manure were higher than those from untreated poultry manure, as measured by the evaporation rate of NH3. However, when measuring the evaporation rate of NH3 from the digestate, it was found that NH3 emission rates showed similar trends.

Development of a farm-scale, quasi-mechanistic model to estimate ammonia emissions from commercial manure-belt layer houses

Poultry production significantly contributes to atmospheric ammonia (NH3) emissions, causing concerns over their environmental impacts and the effects on human and bird health inside the poultry houses. A model is needed to estimate NH3 emissions from poultry facilities in order to develop effective mitigation strategies and science-based regulations. The laboratory-scale mechanistic NH3 emission model developed by Tong, Zhao, Heber, and Ni (2020) requires extensive monitoring and laboratory work for the inputs and therefore cannot be conveniently used by producers or regulatory agencies. Based on this mechanistic model, a farm-scale model was developed for estimating dynamic NH3 emission rates from commercial manure-belt layer houses. Sub-models were developed to estimate the inputs of the mechanistic model from farm-scale conditions that are commonly known during poultry production. Computational fluid dynamics (CFD) models and analyses of manure characteristics were used to estimate air conditions, manure properties, and NH3 emission areas inside layer houses. The model estimated daily NH3 emission from typical commercial manure-belt layer houses for given dates with input data consisting of hen inventory, ambient air temperature, house ventilation mode and rate, and manure management practices. Model performance was evaluated by comparison with NH3 emission data from four commercial manure-belt layer houses with different ventilation systems. Uncertainties of 26–32% relative to the mechanistic model were obtained based on the uncertainties of individual sub-models along with their corresponding sensitivities. The model had an acceptable performance during ordinary egg production (p-value = 0.10–0.61), but it needs further development for special events such as moulting and introduction of new flocks.

On-road emission measurements of reactive nitrogen compounds from heavy-duty diesel trucks in China

Emissions of major reactive nitrogen compounds, including nitric oxide (NO), nitrogen dioxide (NO2) and ammonia (NH3), from heavy-duty diesel vehicles (HDDVs) place substantial pressure on air quality for many large cities in China. To control nitrogen oxide (NOX) emissions from HDDVs, selective catalytic reduction (SCR) systems have been widely used since the China IV standards. To investigate the impacts of aftertreatment technologies and driving conditions on real-world emissions of reactive nitrogen compounds, a portable emissions measurement system was employed to test eighteen heavy-duty diesel trucks in China. The results showed that the China IV and China V HDDVs with appropriate SCR functionality could reduce NOX emissions by 36% and 53%, respectively, compared to the China III results, although their real-world emissions were still higher than the corresponding emission limits for regulatory engine tests. For these HDDVs, five samples were tested with NH3 emissions, ranging from 1.67 ppm to 51.49 ppm. The NH3 emission rates tended to significantly increase under high-speed driving conditions. The results indicate that the current SCR technology may have certain risks in exceeding the future China VI NH3 limit. However, five China IV/V HDDVs were found to have SCR temperature sensors that were intentionally tampered with, resulting in comparable or even higher NOX emissions and zero NH3 emissions. Increased NO2 emissions due to the adoption of diesel oxidation catalysts and diesel particulate filters were also found from our experiments. This study highlights the importance of enhancing in-use compliance requirements and eliminating aftertreatment tampering for China IV and China V HDDVs.

Determination of the mass transfer coefficient of ammonia emissions from dairy open lots using a scale model

Open lots are commonly used to provide outdoor free ranging spaces for dairy cows in many countries such as China and the USA. For this type of operation, the manure characteristics, floor types and environmental conditions, which potentially affect gaseous emissions from manure, are quite different from those of indoor systems. The estimation of NH3 emissions from manure depends greatly on the mass transfer coefficient, an empirical constant determined by environmental factors in the process-based emission model. Using a scale model, this study measured ammonia emissions to be expected from dairy open lots, based on different combinations of different surface air velocities (0.6–2.2 m s−1), air temperatures (15–35 °C) and relative humidity values (20–60%). Based on the two-film theory, the overall mass transfer coefficient (KOL) of NH3 was calculated from directly measured NH3 emission rates and the ammonium nitrogen content, temperature, and pH of manure. As an indicator of the driving potential of gaseous volatilisation, the vapour pressure deficit (VPD) was estimated using air temperature and relative humidity. As the VPD and surface air velocity increased, the measured NH3 emission rates ranged from 1.35 to 19.18 mg kg−1 h−1, and the estimated KOL of NH3 from dairy open lots was within the range of 1.48 × 10−6 – 7.86 × 10−6 m s−1. Using the air velocity and VPD as variables, a non-linear empirical model was developed to estimate the KOL for NH3 emissions from manure on dairy open lots (R2 = 0.69). The normalised mean error of the model was approximately 19.4%.

Characterization of particulate and gaseous pollutants from a French dairy and sheep farm

Agricultural activities highly contribute to atmospheric pollution, but the diversity and the magnitude of their emissions are still subject to large uncertainties. A field measurement campaign was conducted to characterize gaseous and particulate emissions from an experimental farm in France containing a sheep pen and a dairy stable. During the campaign, more than four hundred volatile organic compounds (VOCs) were characterized using an original combination of online and off-line measurements. Carbon dioxide (CO2) and ammonia (NH3) were the most concentrated compounds inside the buildings, followed by methanol, acetic acid and acetaldehyde. A CO2 mass balance model was used to estimate NH3 and VOC emission rates. To our knowledge, this study constitutes the first evaluation of emission rates for most of the identified VOCs. The measurements show that the dairy stable emitted more VOCs than the sheep pen. Despite strong VOC and NH3 emissions, the chemical composition of particles indicates that gaseous farm emissions do not affect the loading of fine particles inside the farm and is mainly explained by the low residence time inside the buildings. The experimental dataset obtained in this work will help to improve emissions inventories for agricultural activities.

Emissions of ammonia and hydrogen sulfide from typical dairy barns in central China and major factors influencing the emissions

There are few studies on the concentrations and emission characteristics of ammonia (NH3) and hydrogen sulfide (H2S) from Chinese dairy farms. The purpose of this study was to calculate the emission rates of NH3 and H2S during summer and to investigate influencing factors for NH3 and H2S emissions from typical dairy barns in central China. Eleven dairy barns with open walls and double-slope bell tower roofs from three dairy farms were studied. Five different locations in each barn were sampled both near the floor and at 1.5 m above the floor. Concentrations of NH3 and H2S were measured using the Nessler’s reagent spectrophotometry method and the methylene blue spectrophotometric method, respectively. NH3 concentrations varied between 0.58 and 4.76 mg/m3 with the average of 1.54 mg/m3, while H2S concentrations ranged from 0.024 to 0.151 mg/m3 with the average of 0.092 mg/m3. The concentrations of NH3 and H2S were higher during the day than at night, and were higher near the ground than at the height of 1.5 m, and were higher in the manure area than in other areas. NH3 and H2S concentrations in the barns were significantly correlated with nitrogen and sulfur contents in feed and manure (P < 0.05), and with temperature inside the barns (P < 0.05). Calculated emission rates of NH3 ranged from 13.8 to 41.3 g NH3/(AU·d), while calculated emission rates of H2S ranged from 0.15 to 0.46 g H2S/(AU·d). These results will serve as a starting point for a national inventory of NH3 and H2S for the Chinese dairy industry.

Generation and Emission of Ammonia During the Full-Scale Composting of Sewage Sludge

The generation and emission of ammonia (NH3) were studied using a continuous monitoring system in an established sewage sludge treatment plant. Results showed that NH3 generation within the pile differed from the emissions at the pile surface during composting. The maximum NH3 concentration reached 600 mg m−3 inside the composting pile and 200 mg m−3 in the outlet gas. The mass of N determined in NH3 generations was 9.97 g kg DM−1, which was 2.57 times higher than the mass of N in NH3 emissions. The highest NH3 generation and emission masses in one aeration cycle occurred during the mesophilic (10.19 mg kg−1) and early thermophilic (6.91 mg kg−1) phases. The relationship between NH3 generation rates and time during one aeration cycle and different composting phases could be expressed as a logarithmic equation, and the relationship between NH3 emission rate and time could be expressed as a quadratic equation.

Effects of antibiotic-free pig rearing on ammonia emissions from five pairs of swine rooms in a wean-to-finish experiment

Antibiotic use and ammonia (NH3) emissions during animal production are two environmental issues of worldwide concern. However, the role of antibiotics on NH3 emissions is still unknown. This study evaluated the effects of rearing pigs without antibiotics on NH3 emissions from a swine experimental building starting with 657 piglets during a wean-to-finish production cycle of 154 days. Pigs were reared in two groups of 10 rooms that were divided into five 2-room pairs (P1–P5) and fed in nine dietary phases. Each pair consisted of one room without antibiotics (no antibiotics in the diet, water, or injectable) and another room as a positive control. Control animals were fed diets containing carbadox-10 (phases 1–4), chlortetracycline (CTC, phase 5), lincomix (phases 6–7), and tylan 40 (phases 8–9). Temperatures in the pig living space and the under-floor manure pit headspace were continuously measured. Ventilation rates at all wall fans and pit fans were obtained by continuous monitoring. Ammonia concentrations in the wall and pit fan exhaust air, and in room inlet air were measured with two multi-gas monitors. Only days that contained at least 18 h of data each day were validated and used. The study generated 1337 room-days of valid data of NH3 emission rates, with a data completeness of 88.6%. Daily mean NH3 emission patterns demonstrated large variations between the paired rooms and among different pairs. Within the individual 2-room pairs, no NH3 emission differences were found in P1 (rooms 1 and 2, p = 0.34) and P2 (rooms 3 and 4, p = 0.44). Significant differences were found in P3–P5 (p < 0.01). The antibiotic-free rooms emitted more NH3 from P3 and P4, but less NH3 from P5. However, the combined cycle mean NH3 emissions from the group of five antibiotic-free rooms and the group of five control rooms were 41.6 ± 10.5 and 39.4 ± 10.6 g d−1 AU−1 (mean ± standard deviation. AU = 500 kg live body weight), respectively. Therefore, there was no statistical difference in combined cycle mean NH3 emissions from rearing pigs with or without antibiotics (p = 0.78). This study also revealed that experiments with multiple replicates and long NH3 monitoring durations were necessary to avoid potential misinterpretation of experimental results.

Influences of the thermophilic period on biodegradation and nitrogen loss in stimulated vegetable waste composting

Development of thermophilic composting with ultrahigh temperature (over 70 °C) would enable the vegetable wastes compost harmless, due to the inactivation of the potential viral pathogens. The present study respectively analyzed the influences of temperature (55 °C, 65 °C, and 75 °C), lasting time of temperature over 70 °C (12 h, 24 h, and 48 h), and duration over certain temperature (10 days over 50 °C, 5 days over 60 °C and 1 day over 70 °C), on biodegradation and nitrogen loss in composting, by controlling the temperature condition in stimulated composting system. The results showed that in the simulated condition, high temperature over 75 °C affected the microbial degradation of organic matter, but the activity of microorganisms could recover if the duration is no more than 24 h, which implied that the thermophilic stage of high temperature with short duration was able to inactivate the pathogenic organisms without affecting the composting process. More NH3 emission was observed in the stimulated composting of consistent 65 °C than 55 °C and 75 °C, while the TN loss rate was higher in the consistent 55 °C treatment. The NH3 emission amount was increased with the increase of the duration of 75 °C, while the TN loss rate was the lowest when the duration is 24 h. The results suggested that high temperature did not necessarily promote the emission of ammonia, and the influences on NH3 emission and TN loss rate did not always consistent. Furthermore, even the NH3 emission and TN loss rate were increased along with the temperature increase, the difference of the TN loss rate between the two treatments, over 60 °C 5 days and over 70 °C 1 day, was not significant. In conclusion, the thermophilic stage of the temperature over 70 °C with a short duration to inactivate the potential viral pathogens will not significantly increase the nitrogen loss and influence the composting process.

Vehicular exhaust contributions to high NH3 and PM2.5 concentrations during winter in Tokyo, Japan

Concentrations of PM2.5 in Tokyo, a densely populated megacity, often increase because of NH4NO3 formation under low-wind conditions during winter. To obtain source information of NH3 as a NH4NO3 precursor, hourly NH3 and NH4+ concentrations were measured at an urban site in Tokyo in December 2017. Results show that PM2.5 and NH4+ concentrations increased simultaneously under low-wind and low-temperature conditions along with NH3, NOx, CO, and optical black carbon (OBC) concentrations. The remaining NH4+ (herein, ΔNH4+) subtracted from observed NH4+ to equivalent SO42− concentration correlated well with NO3− in PM2.5, indicating the existence of fine NH4NO3 particles. Regression analysis of hourly NH3 + ΔΝH4+ concentrations with CO, NOx, and OBC showed significant correlation. Virtual emission rates (VER) of NH3 per motor vehicle in Tokyo were estimated using observed relations between NH3 + ΔΝH4+ and OBC, etc. with data from vehicular statistics: they were 3.7–32 mg/km. The regression of NH3 + ΔΝH4+ with OBC concentrations indicated an intercept of about 3.2 ppb, which is about half of the monthly average in December. This result implies that the non-vehicular source strength was nearly the same strength as the bulk vehicular emissions of NH3 during winter in Tokyo.

Meta-modeling methods for estimating ammonia volatilization from nitrogen fertilizer and manure applications

Accurate estimations of ammonia (NH3) emissions due to nitrogen (N) fertilization are required to identify efficient mitigation techniques and improve agricultural practices. Process-based models such as Volt’Air can be used for this purpose because they incorporate the effects of several key factors influencing NH3 volatilization at fine spatio-temporal resolutions. However, these models require a large number of input variables and their implementation on a large scale requires long computation times that may restrict their use by public environmental agencies. In this study, we assess the capabilities of various types of meta-models to emulate the complex process-based Volt’Air for estimating NH3 emission rates from N fertilizer and manure applications. Meta-models were developed for three types of fertilizer (N solution, cattle farmyard manure, and pig slurry) for four major agricultural French regions (Bretagne, Champagne-Ardenne, Ile-de-France, and Rhône-Alpes) and at the national (France) scale. The meta-models were developed from 106,092 NH3 emissions simulated by Volt’Air in France. Their performances were evaluated by cross-validation, and the meta-models providing the best approximation of the original model were selected. The results showed that random forest and ordinary linear regression models were more accurate than generalized additive models, partial least squares regressions, and least absolute shrinkage and selection operator regressions. Better approximations of Volt’Air simulations were obtained for cattle farmyard manure (3% < relative root mean square error of prediction (RRMSEP) < 8%) than for pig slurry (17% < RRMSEP < 19%) and N solution (21% < RRMSEP < 40%). The selected meta-models included between 6 and 15 input variables related to weather conditions, soil properties and cultural practices. Because of their simplicity and their short computation time, our meta-models offer a promising alternative to process-based models for NH3 emission inventories at both regional and national scales. Our approach could be implemented to emulate other process-based models in other countries.

Ammonia, Nitrous Oxide, Carbon Dioxide and Methane Emissions from Commercial Broiler Houses in Mediterranean Portugal

Limited data are available on ammonia (NH3), nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) emissions from poultry housing in Mediterranean countries. The aim of the present study was to assess the NH3, N2O, CO2 and CH4 emission rates from commercial breeding hen and broiler houses under Mediterranean climate conditions. Research was conducted at one commercial breeding hen house and in two commercial broiler houses located in central Portugal. The environmental conditions, gas concentrations and ventilation rates were measured in the cold (8.0 ± 2.1 °C) and hot (20.7 ± 1.9 °C) season for the breeding hen house, whereas for the two broiler houses, measurements were made during one fattening cycle in the fall (17.3 ± 1.7 °C) season. Results showed that the annual average emission rates for breeding hen and broiler houses were 0.52 ± 0.27 and 0.06 ± 0.01 for NH3, 0.030 ± 0.042 and 0.006 ± 0.001 for N2O, 169.6 ± 56.2 and 58.0 ± 15.1 for CO2 and 0.092 ± 0.131 and 0.0113 ± 0.0002 g day−1 bird−1 for CH4, respectively. The N2O emission rates observed in breeding hen houses may have been overestimated, being higher than previously reported for Mediterranean countries.