Main Source Of Ammonia Research Articles

Improved global agricultural crop- and animal-specific ammonia emissions during 1961–2018

Agriculture is the main source of ammonia (NH3) emissions which result in air pollution and degrade human health. However, the global pattern of NH3 emissions still remains uncertain, and very few studies report the crop- and animal-specific NH3 emissions both regionally and globally. Here, we developed an improved long-term (1961–2018) agricultural NH3 emissions inventory considering the detailed information of crop- and animal-specific sources at 0.5o grids. Global agricultural NH3 emissions were estimated as 39.2 Tg N yr-1 averaged over 1961–2018, driven by livestock production (58.4%) and cropland (41.6%). Cattle, rice, maize and wheat together explain about 53.4% of total agricultural NH3 emissions. Agricultural NH3 emissions increased by 225% from 18.5 Tg N in 1961–60.1 Tg N in 2018 with the increase rate of 2.1% yr-1 (for cropland 3.8% yr-1 and for livestock 1.3% yr-1). Regarding regions, China, India, Brail, Pakistan, United States and European Union accounted for over half of total agricultural NH3 emissions. The hotspots of agricultural NH3 emissions have shifted from the United States and European Union in the 1960s to China and India in recent years. Our findings benefit the understanding of agricultural NH3 dynamics by crops and animals and provide an important reference for the formulation of NH3 pollution prevention and control policy.

How do moisture content, friability, and crust development of litter influence ammonia concentrations in broiler production?

Litter is the main source of ammonia (NH3) in broiler houses. The quality thereof affects the amount of NH3 volatilized and emitted from the broiler house as well as the welfare of the birds. A trial was conducted to determine how the addition of water to broiler litter (by spraying the surface) and raking of the litter or leaving the litter undisturbed will influence NH3 concentrations at litter level, litter composition, bird welfare, and performance under experimental conditions. A total of 2160 Ross 308 male broilers were divided into the following 6 treatments, each with 6 replicates of 60 animals: NR(0) = no raking of the litter, no water added; R(0) = raking of the litter, no water added; NR(1.5) = no raking of the litter, 1.5 L of water added; R(1.5) = raking of the litter, 1.5 L of water added; NR(3.0) = no raking of the litter, 3.0 L of water added; R(3.0) = raking of the litter, 3.0 L of water added. The addition of water and raking of the litter was introduced at 10 d of age, with a frequency of 2 to 3 times per week. At 38 d of age, NH3 concentrations were higher for the raked litter treatments than the treatments which were not raked (P < 0.001). The higher NH3 concentrations of the raked litter treatments coincided with a higher litter pH (P < 0.001) and temperature (P R × W < 0.001) as well as a lower uric acid and total nitrogen (N) concentration in the litter at 37 d of age. The addition of water to the litter resulted in lower litter quality scores at 29 and 37 d of age (P < 0.001) and a higher incidence of foot lesions at 29 (P W = 0.006) and 37 (P R × W = 0.025). Regardless of raking or not raking the litter, addition of moisture to the litter lead to litter of lower quality and subsequent higher incidence of foot lesions in broilers. This study demonstrates that the development of a crust on top of the litter layer reduces the formation and concentration of NH3 volatilized from the litter. Compacted litter resulted in lower NH3 concentrations while friable litter led to more NH3 being volatilized from the litter.

Bio-Acidification of Cattle Slurry with Whey Reduces Gaseous Emission during Storage with Positive Effects on Biogas Production

Livestock manure is the main source of ammonia (NH3) and greenhouse gases emissions (GHG), which can be reduced by acidifying manure. This work assessed the effect of acidification of cattle slurry using whey on NH3 and GHG emissions during storage, followed by its usage for biogas production. Tests were conducted to optimize the dose and the frequency at which whey was applied to cattle slurry. Two of the analyzed treatments, AS1-100 and AS1-10, showed reduced emissions when compared with the control AS1-0 without whey. In AS1-100, 100% of the optimized amount of whey was added to the slurry at the beginning of the test, while in AS1-10 whey was fractioned in 10 applications (one per day) corresponding to 10% of the total. Batch-type anaerobic digestion assays using AS1-100 and AS1-10 as feedstock resulted in a significant increase in methane production when compared with the anaerobic digestion of AS1-0 (+33% and +53%, respectively). The best results in terms of gas emissions abatement and methane production during anaerobic digestion were obtained when a low organic loading rate of whey was used. These results demonstrate that the use of whey for slurry acidification is a viable approach for potentially solving the economic and environmental problems of GHG and NH3 emissions during slurry storage, whereby increasing energy and environmental sustainability.

Study on Enhanced Methods for Calculating NH3 Emissions from Fertilizer Application in Agriculture Sector.

Ammonia is a representative PM-2.5 secondary product, and the need for management is emerging as health and living damage caused by fine particulate matter worsens. The main source of ammonia is the agricultural sector, and in Korea, 79% of the total ammonia emissions are emitted from the agricultural sector. Among them, there is high uncertainty about how to calculate emissions from ammonia discharged from fertilizer use, and inventory in the U.S. and Europe is borrowed, so inventory needs to be improved according to the situation in Korea. In this study, the ammonia inventory in the agricultural sector in Korea and abroad was examined, and additional activity data that can be used were reviewed. In addition, in order to improve the emission calculation method, the emission was calculated in three ways by different factors. As a result, it was confirmed that the amount of discharge varies depending on the type of soil use or whether cultivated crops are considered, and the possibility of excessive fertilizer top-dress by farmers was confirmed. In order to calculate the emission at a more detailed level based on this study, basic data such as fertilizer input method and regional distribution of crops should be systematically collected, and related follow-up studies should be conducted.

Do alternative inventories converge on the spatiotemporal representation of spring ammonia emissions in France?

Abstract. Agriculture is the main source of ammonia (NH3) in France, an important gaseous precursor of atmospheric particulate matter (PM). National and global emission inventories are known to have difficulty representing the large spatial and temporal variability inherent to atmospheric NH3. In this study, we compare NH3 emissions in France during spring 2011 from one reference inventory, the TNO inventory, and two alternative inventories that account in different manners for both the spatial and temporal variabilities of the emissions: (i) the NH3SAT satellite-derived inventory based on IASI NH3 columns and (ii) the CADASTRE-CIT inventory that combines NH3 emissions due to nitrogen fertilization calculated with the mechanistic model VOLT'AIR on the database of the CADASTRE_NH3 framework and other source emissions from the CITEPA. The total spring budgets, from March to May 2011, at the national level are higher when calculated with both alternative inventories than with the reference, the difference being more marked with CADASTRE-CIT. NH3SAT and CADASTRE-CIT inventories both yield to large NH3 spring emissions due to fertilization on soils with high pH in the northeastern part of France (65 and 135 kt NH3, respectively, vs. 48 kt NH3 for TNO-GEN), while soil properties are not accounted for by the TNO-GEN methodology. For the other parts of France, the differences are smaller. The timing of fertilization and associated ammonia emissions is closely related to the nitrogen requirements and hence the phenological stage of the crops, and therefore to the crop year's specific weather conditions. Maximum emissions are observed in March for 2011 for some regions for both alternative inventories, while April is the period with maximum emissions for the reference inventory regardless of the region or the year. Comparing the inventories at finer temporal resolutions, typically at daily scale, large differences are found. The convergence of alternative, independent and complementary methods on the spatiotemporal representation of the spring NH3 emissions, particularly over areas where the contribution of mineral fertilizer spreading to the spring budget is strong, encourages further developments in both prospective complementary directions, as this will help improve national NH3 emission inventories.

MTOR - Mediated protein synthesis by inhibiting protein catabolism in Chinese perch (Siniperca chuatsi)

Activation of the mechanistic target of rapamycin (mTOR) pathway is known to promote protein synthesis by enhancing mRNA translation. However, there have been few literatures on the effect of mTOR on protein metabolism in non-mammals. The main source of ammonia in fish comes from protein catabolism. The key step of protein catabolism involves the deamination and/or transamination of amino acids. This study is aimed to explore the mechanism underlying mTOR pathway influencing protein retention from the perspective of protein catabolism. Chinese perch were fasted for 24 h and divided into 4 groups randomly before intracerebroventricular (ICV) injection: (1) control group for leucine; (2) leucine group; (3) control group for leucine and rapamycin; (4) leucine and rapamycin group. Food intake was equivalent between each control and treatment groups at each time point (0.5, 4, 12 and 24 h post-injection). Ammonia-N excretion rate, blood glucose, S6 phosphorylation level, and expression of relative genes of protein catabolism (GDH, AMPD, AST, ALT) were determined. The results indicated that the pS6 level was increased, and that the ammonia-N excretion rate, blood glucose, and mRNA level of protein catabolism genes (GDH and AMPD) were significantly decreased after injection with leucine, while those changes were reversed after injection with leucine and rapamycin. Our study not only reveals the mechanism by which mTOR mediates protein synthesis by inhibiting protein catabolism in Chinese perch, but also provides reference for improving the utilization of feed protein.

Slurry Acidification as a Tool to Reduce Ammonia Emissions

Ammonia emissions are a worldwide major environmental concern. In 2017, ammonia emissions in the European part of Russia amounted to 80.9 thousand tons, of which up to 56.9 thousand tons came from agriculture. The main source of ammonia in this sector is the farm animal/poultry manure (slurry) utilisation technologies. Slurry acidification technology (SAT) is one of the methods to reduce ammonia emissions. ( Research purpose ) To assess the potential application of this technology in the Russian part of the Baltic Sea catchment area within the North-West Federal District of the Russian Federation. ( Materials and methods ) The area under study included Republic of Karelia, Kaliningrad, Leningrad, Novgorod and Pskov Regions. The authors considered the statistical data on the farm animal stock and the slurry output in the pilot area. The dynamic pattern of pig slurry pH was experimentally determined. The economic efficiency of slurry acidification technology was calculated for two functioning livestock complexes. ( Results and discussion ) According to statistical data, around 11.8 million tons of animal/poultry manure is produced in the pilot area annually, including around 7.4 million tons of slurry, which could potentially be acidified. Three SAT options – in-house, in-storage and in-field application – were considered for the Russian conditions. The main limiting factors for SAR application were identified. The SAT introduction costs and economic benefits were compared. ( Conclusions ) The prospects of SAT introduction in the pilot region were estimated. The need for the integrated research under the Russian conditions involving engineers, biologists, soil scientists, ecologists and other specialists, who could prove the feasibility and economic efficiency of the slurry acidification technology, was established.

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

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

Ammonia desorption from fly ash

The main source of ammonia in ash are residues from an unreacted NH3 from the denitrification process, either from SCR or SNCR systems. The paper discusses the standards of NH3 content in fly ash and presents the most commonly used methods of removing excess ammonia from fly ash. In the next part of the work the results of laboratory tests on NH3 desorption are presented. Desorption was performed on samples of fly ash taken from the electrostatic precipitator of real PC boiler. Removal of NH3 from the ash was carried out in a heating chamber at 130°C and 150°C and detected by an analyser equipped with a NDIR sensor. Additionally, at the temperature of 130°C, the NDIR and analytical methods were compared (in accordance with the BN-750541-05 procedure) and the measurement uncertainty of both methods was estimated.

Feed use and nitrogen excretion of livestock in EU-27

Livestock excreta is a large source of nitrogen (N) in the European Union (EU), used to fertilize crops, and also a main source of ammonia (NH3), nitrous oxide (N2O) and nitrate (NO3−) losses to the environment. The amount of N in excreta mainly depends on the animal category and productivity, and on feed use and management. National inventories of emissions to the environment are often based on different methodologies for the estimation of N excretion. Here, we present a transparent and uniform methodology for estimating annual feed use and N excretion per animal category for all countries of the EU-27, based on the energy and protein requirements of the animals and statistics of feed use and composition, animal number and productivity.The calculated total feed use in the EU-27 was 506Tg dry mass in 2010. Dairy cows used 29%, other cattle 34%, pigs 17%, chicken 9%, sheep and goats 8%, and other animal categories 3% of the total feed use. Grass and annual forages were mainly used by dairy cows (30 and 49%, respectively) and other cattle (55 and 44%); pigs used most of the feed cereals (53%); protein-rich feed (e.g., soybean meal) were mostly used by pigs (34%) and chicken (24%). Differences between countries in feed use were large, mainly related to variations in national feed supply and animal productivity. Total N excretion of the animals amounted to 9.7Tg in 2010, and varied between countries from 14 to 291kgha−1 of utilized agricultural land. The present study provides a uniform and transparent approach for evaluating feed use and N excretion in all countries of the EU-27. Our results underline the significant differences in N excretions between EU countries as a result of feed use variations, suggesting the need for basing N excretion estimations on feed use data. The dataset present in this study may serve as a basis for such efforts, also to improve national inventories of N emissions.

SLURRY TREATMENT WITH FOOD INDUSTRY WASTES FOR REDUCING METHANE, NITROUS OXIDE AND AMMONIA EMISSIONS

Livestock manure is the main source of ammonia (NH3) emissions and an important source of greenhouse gases (GHG) especially methane (CH4) and nitrous oxide (N2O). Ammonia emissions contribute to eutrophication and acidification of water, soils and ecosystems. The greenhouse gases contribute to the global warming. These gaseous emissions can be reduced by controlling the pH-value of manure. Acidifying the manure can reduce CH4, N2O and NH3 emissions. Inorganic acids are feasible, but have several disadvantages, e.g. soil contaminants. The use of organic acids is an efficient but expensive method; therefore using the food industry wastes which already contain organic acids is highly feasible. The objective of this research is to investigate the effects food industry wastes as manure additives on the emissions of CH4, N2O and NH3. Dairy cattle manure was treated with food industry wastes (whey and waste of citrus and orange juices industry) and the gas flux of CH4, N2O and NH3 were quantified using a specially designed gas detection system which consists of several flasks and a multi-gas monitor. The results showed that the gas fluxes emitted from manure treated with waste of citrus juice industry were 13, 0.219 and 2.523 g m-2 day-1 for CH4, N2O and NH3 respectively. The gas fluxes emitted from manure treated with waste of orange juice industry were 13.58, 0.223 and 2.581 g m-2 day-1 for CH4, N2O and NH3 respectively. The gas fluxes emitted from manure treated with whey were 17.45, 0.279 and 3.063 g m-2 day-1 for CH4, N2O and NH3 respectively. The gas fluxes emitted from the control sample (mixture of manure and water) were 58.21, 0.347 and 18.9 g m-2 day-1 for CH4, N2O and NH3 respectively. Consequently, manure treatment with food industry wastes enabled high reduction rates of gaseous emissions from manure.

Effect of environmental deflector and curtain on air exchange rate in slurry pit in a model pig house

The main source of ammonia and odour from most livestock buildings is the slurry pit. The ammonia emission rate is affected by the air exchange rate in the slurry pit. Reduction of air exchange between slurry pit and room air may reduce the emissions. The hypothesis that using an environmental deflector in the room and curtains in the slurry pit may affect air exchange rate between the slurry pit and the room air was validated. In the experiment, three position angles for the deflector and three arrangements of curtains were investigated in a two-dimensional ventilation chamber under isothermal conditions at two ventilation airflow rates. The airflow pattern, air velocity and turbulence intensity inside the chamber were also recorded. The results showed that the airflow patterns, air velocities and turbulence intensities in the room space near the slatted floor and in the headspace of the pit were influenced by changing deflector angles and curtain numbers. It was found that the lowest pit ventilation and the highest concentration in the headspace of the pit could be achieved by using a deflector's position angle of 45° at both of two airflow rates. On the other hand, it was also found that more curtain numbers under the slatted floor and lower room ventilation rate caused lowest pit air exchange rate and the highest concentration in the headspace of pit.

Gut ammonia production and its modulation

Systemic hyperammonemia has been largely found in patients with cirrhosis and hepatic encephalopathy, and ammonia plays a major role in the pathogenesis of hepatic encephalopathy. However, controversial points remain: a) the correlation between plasma ammonia levels and neurophysiological impairment. The lack of correlation between ammonia levels and grade of hepatic encephalopathy in some cases has been considered a weakness of the ammonia hypothesis, but new methods for ammonia measurements and the implication of systemic inflammation in the modulation of ammonia neurotoxicity could explain this gap; b) the source of ammonia production. Hyperammonemia has been considered as derived from urea breakdown by intestinal bacteria and the majority of treatments were targeted against bacteria-derived ammonia from the colon. However, some data suggest an important role for small intestine ammonia production: 1) the hyperammonemia after porto-caval shunted rats has been found similar in germ-free than in non-germ-free animals. 2) In cirrhotic patients the greatest hyperammonemia was found in portal drained viscera and derived mainly from glutamine deamination. 3) The amount of time required to increase of ammonia (less than one hour) after oral glutamine challenge supports a small intestine origin of the hyperammonemia. As the main source of ammonia in cirrhotics derives from portal drained viscera owing to glutamine deamidation, increased glutaminase activity in the intestine seems to be responsible for systemic hyperammonemia. Lastly, some genetic alterations in the glutaminase gene such as the haplotype TACC could modulate intestinal ammonia production and the risk of overt hepatic encephalopathy in cirrhotics.

E.ON sponsors university research

Hyperammonemia and severe amino acid imbalances play central role in hepatic encephalopathy (HE). In the article is demonstrated that the main source of ammonia in cirrhotic subjects is activated breakdown of glutamine (GLN) in enterocytes and the kidneys and the main source of GLN is ammonia detoxification to GLN in the brain and skeletal muscle. Branched-chain amino acids (BCAA; valine, leucine, and isoleucine) decrease due to activated GLN synthesis in muscle. Aromatic amino acids (AAA; phenylalanine, tyrosine, and tryptophan) and methionine increase due to portosystemic shunts and reduced ability of diseased liver. The effects on aminoacidemia of the following variables that may affect the course of liver disease are discussed: nutritional status, starvation, protein intake, inflammation, acute hepatocellular damage, bleeding from varices, portosystemic shunts, hepatic cancer, and renal failure. It is concluded that (1) neither ammonia nor amino acid concentrations correlate closely with the severity of liver disease; (2) BCAA/AAA ratio could be used as a good index of liver impairment and for early detection of derangements in amino acid metabolism; (3) variables potentially leading to overt encephalopathy exert substantial but uneven effects; and (4) careful monitoring of ammonia and aminoacidemia may discover important break points in the course of liver disease and indicate appropriate therapeutic approach. Of special importance might be isoleucine deficiency in bleeding from varices, arginine deficiency in sepsis, and a marked rise of GLN and ammonia levels that may appear in all events leading to HE.

President's corner

Hyperammonemia and severe amino acid imbalances play central role in hepatic encephalopathy (HE). In the article is demonstrated that the main source of ammonia in cirrhotic subjects is activated breakdown of glutamine (GLN) in enterocytes and the kidneys and the main source of GLN is ammonia detoxification to GLN in the brain and skeletal muscle. Branched-chain amino acids (BCAA; valine, leucine, and isoleucine) decrease due to activated GLN synthesis in muscle. Aromatic amino acids (AAA; phenylalanine, tyrosine, and tryptophan) and methionine increase due to portosystemic shunts and reduced ability of diseased liver. The effects on aminoacidemia of the following variables that may affect the course of liver disease are discussed: nutritional status, starvation, protein intake, inflammation, acute hepatocellular damage, bleeding from varices, portosystemic shunts, hepatic cancer, and renal failure. It is concluded that (1) neither ammonia nor amino acid concentrations correlate closely with the severity of liver disease; (2) BCAA/AAA ratio could be used as a good index of liver impairment and for early detection of derangements in amino acid metabolism; (3) variables potentially leading to overt encephalopathy exert substantial but uneven effects; and (4) careful monitoring of ammonia and aminoacidemia may discover important break points in the course of liver disease and indicate appropriate therapeutic approach. Of special importance might be isoleucine deficiency in bleeding from varices, arginine deficiency in sepsis, and a marked rise of GLN and ammonia levels that may appear in all events leading to HE.

Aplicação do método da carga máxima total diária (CMTD) para a amônia no Rio Atibaia, região de Campinas/Paulínia - SP

Neste estudo foram avaliadas a capacidade de suporte e o estado de degradação do Rio Atibaia, considerando a ameaça para a vida aquática pela presença da Amônia, a qual representa um dos principais riscos às comunidades aquáticas no Rio Atibaia. Com este objetivo foi aplicado o método da Carga Máxima Total Diária (CMTD), da Agência de Proteção Ambiental dos Estados Unidos (EPA). Os resultados revelaram que as cargas de Amônia aumentavam progressivamente ao longo do Rio Atibaia, principalmente devido às fontes pontuais. As cargas de Amônia diárias assumiram valores de 30 a 5000 kg NH3. A capacidade de suporte das águas Rio Atibaia, para proteger a vida aquática contra os efeitos tóxicos da Amônia, tem sido violadas em trechos próximos à sua foz. A degradação dessas águas foi mais intensa na estação seca. Este trabalho mostrou que o esgoto doméstico não-tratado de uma população aproximada de 250 mil habitantes da cidade de Campinas, via Ribeirão Anhumas, é a principal fonte de Amônia na bacia do Rio Atibaia, apesar do grande número de indústrias ali presentes.

Helicobacter pylori, harmful to the brain?

See article on page 605 Traditional views of the pathogenesis of hepatic encephalopathy (HE) have emphasised the role of neurotoxins arising from the gut. These compounds gain access to the...

Analysis of risk factors for chronic hepatic encephalopathy: the role of Helicobacter pylori infection

Objective: Elevated blood ammonia is an important pathogenic factor of hepatic encephalopathy. Although colonic bacteria are considered the main source of ammonia, the stomach in subjects with urease-producing Helicobacter pylori ( H. pylori) is an alternative site. The objective of this study was to determine whether H. pylori is associated with this complication. Methods: After assessing liver function and portal hypertension, 55 cirrhotics were evaluated for encephalopathy and H. pylori infection. Response to 2 weeks of amoxicillin (2 g/day) and omeprazole (40 mg/day) was then assessed in 17 (13 H. pylori-positive, four H. pylori-negative) encephalopathic subjects. Results: H. pylori infection was more common (67% vs 33%, p = 0.004) among encephalopathic patients. Additional factors associated with encephalopathy included older age (60.1 ± 1.5 vs 49.8 ± 2.4 yr, p = 0.001), lower albumin (3.17 ± 0.08 vs 3.69 ± 0.12 g/dl, p = 0.001), higher total bilirubin (2.24 ± 0.20 vs 1.53 ± 0.23 mg/dl, p = 0.034), greater ascites score (0.8 ± 0.1 vs 0.3 ± 0.1, p = 0.01), greater diuretic score (1.1 ± 0.1 vs 0.3 ± 0.1, p = 0.002), and greater modified Child score (6.7 ± 0.3 vs 5.1 ± 0.3, p = 0.001). When adjusted for severity of cirrhosis and age, H. pylori continued to demonstrate a statistical association ( p = 0.039). After anti- H. pylori therapy, symptomatology in infected encephalopathic patients appeared to improve, whereas noninfected subjects were unaffected. Conclusion: In cirrhotic patients, H. pylori infection is associated with hepatic encephalopathy, especially in younger patients with decompensated liver disease.

Analysis of risk factors for chronic hepatic encephalopathy: the role of Helicobacter pylori infection.

Elevated blood ammonia is an important pathogenic factor of hepatic encephalopathy. Although colonic bacteria are considered the main source of ammonia, the stomach in subjects with urease-producing Helicobacter pylori (H. pylori) is an alternative site. The objective of this study was to determine whether H. pylori is associated with this complication. After assessing liver function and portal hypertension, 55 cirrhotics were evaluated for encephalopathy and H. pylori infection. Response to 2 weeks of amoxicillin (2 g/day) and omeprazole (40 mg/day) was then assessed in 17 (13 H. pylori-positive, four H. pylori-negative) encephalopathic subjects. H. pylori infection was more common (67 % vs 33%, p = 0.004) among encephalopathic patients. Additional factors associated with encephalopathy included older age (60.1 +/- 1.5 vs 49.8 +/- 2.4 yr, p = 0.001), lower albumin (3.17 +/- 0.08 vs 3.69 +/- 0.12 g/dl, p = 0.001), higher total bilirubin (2.24 +/- 0.20 vs 1.53 +/- 0.23 mg/dl, p = 0.034), greater ascites score (0.8 +/- 0.1 vs 0.3 +/- 0.1, p = 0.01), greater diuretic score (1.1 +/- 0.1 vs 0.3 +/- 0.1, p = 0.002), and greater modified Child score (6.7 +/- 0.3 vs 5.1 +/- 0.3, p = 0.001). When adjusted for severity of cirrhosis and age, H. pylori continued to demonstrate a statistical association (p = 0.039). After anti-H. pylori therapy, symptomatology in infected encephalopathic patients appeared to improve, whereas noninfected subjects were unaffected. In cirrhotic patients, H. pylori infection is associated with hepatic encephalopathy, especially in younger patients with decompensated liver disease.

Volatile emissions of housing systems for cattle

In regions with high livestock density, deposition of ammonia can have a serious impact on the environment, especially natural vegetation and groundwater. In the Netherlands roughly 15% of the total ammonia emission originates from cattle houses and storage of cattle manure. This paper describes the experiences and results of research carried out in order to develop housing systems with a reduced emission of ammonia. Though manure is the main source of ammonia, it has become evident that not only manure storage but also the cattle house floor is an important source of ammonia evaporation. The work thus far has not resulted in a complete picture of the ammonia evaporation, nor in the development of an applicable housing system with reduced emission. The emission from outside storage tanks can be reduced by 70–90% by covering the tank. The different factors which have an effect are discussed. The emission of ammonia coincides with the emission of odours. Though ammonia hardly contributes to the odour sensation, the control of both emissions can often be combined. H 2S is a very odorous compound, but the low emission of H 2S as such does not cause severe pollution, but together with CH 4, it complicates measures to prevent ammonia emission.