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PubMed2001

A tunable diode laser system for ammonia flux measurements over multiple plots.

This paper reports on the field testing of a tunable diode laser trace gas analyzer system for micrometeorological monitoring of ammonia fluxes. This system uses infrared absorption spectroscopy to measure atmospheric ammonia concentrations and the fluxgradient method to relate the measured concentration gradient to a flux of ammonia. For the field tests, we monitored ammonia fuxes over three plots receiving different manure applications. Each plot was sampled for 15 or 30 min of each hour, producing a high-temporal resolution data set. Analysis of the system response showed that ammonia adsorption to the tubing walls was greatly reduced by the system design and did not interfere with the flux measurement.

Agriculture↗
PubMed1999

Metabolic capacity for L-citrulline synthesis from ammonia in rat isolated colonocytes.

Ammonia is present at high concentration in the colon lumen and is considered a colon cancer suspect. Furthermore, ammonia usually eliminated by the liver in the ornithine cycle is considered highly toxic to cerebral function when present in excess in the blood plasma. Therefore, the metabolic pathways involved in ammonia metabolism in colonocytes were studied in the present study. Rat colonocytes were found equipped with low carbamoylphosphate synthase I activity, high ornithine carbamoyltransferase and arginase activities and low argininosuccinate synthase activity. High (10 and 50 mmol/l) NH4Cl concentrations but not low concentrations (1 and 5 mmol/l) were found able to increase respectively 3- and 10-fold the conversion of radioactive L-arginine to L-citrulline. In contrast, very low capacity for L-citrulline conversion to L-arginine is found in colonocytes. It is concluded that an incomplete ornithine cycle is operative in colonocytes which results in ammonia stimulated L-citrulline production. The contribution of this metabolic pathway in relation to ammonia detoxication by colonocytes is discussed.

Ammonia↗
PubMed2000

Ammonia concentration in bovine follicular fluid and its effect during in vitro maturation on subsequent embryo development.

10 mm) to determine ammonia concentration. Ammonia concentration was greater (P<0.001) in the bFF from smaller follicles compared with bFF from larger follicles, and ammonia concentration decreased (P10 mm follicles, respectively. In Experiment 2, abattoir oocytes (n=2885) were matured in vitro in media containing ammonia at the concentrations of 0 microM (Control), 29 microM (A1), 88 microM (A2), 132 microM (A3), 176 microM (A4) and 356 microM (A5), followed by in vitro fertilization and culture. There was no difference (P0.05) in cleavage rates and morula or blastocyst development between treatments, indicating that in vitro exposure of bovine oocytes to ammonia does not adversely influence subsequent embryonic development.

Ammonia↗
PubMed1994

Effect of ammonia on endocytosis, cytokine production and lysosomal enzyme activity of a microglial cell line.

Ammonia is a natural lysosomotropic compound. Concentrations of ammonium acetate > 2 mM impaired the phagocytic activity of BV-2 cells, an immortalized microglial cell line, as was determined by the uptake of fluorescent latex microspheres of different sizes. In contrast, an increase in the uptake of fluorescent dextran was observed with the elevation in ammonium acetate concentrations. This indicates that ammonia affects phagocytotic and pinocytotic activities of BV-2 cells differently. Interferon-gamma- and polyinosinic-polycytidylic acid-stimulated secretion of IL1 alpha as well as LPS-stimulated secretion of IL6 decreased with an elevation in ammonium acetate concentrations. The constitutive secretion of IL1 alpha was not significantly affected by ammonium acetate. However, an increase in LPS-stimulated IL1 alpha secretion was observed at 10 mM and 20 mM ammonium acetate. High concentrations of ammonia affected the activity of lysosomal enzymes of the BV-2 cells. Acid phosphatase and alpha-glucosidase activities increased with the increase in ammonium acetate up to 20 mM. The activity of cathepsin D was increased at 5 mM, but decreased at higher ammonia concentrations. The effects of ammonia on microglial functions are discussed with respect to pathogenetic mechanisms of dementia of the Alzheimer type.

Acetates↗
PubMed2003

Air stripping of ammonia from pig slurry: characterisation and feasibility as a pre- or post-treatment to mesophilic anaerobic digestion.

The objective of the present paper has been to study the effect of pig slurry waste type, fresh or anaerobically digested, and the effect of initial pH on ammonia air stripping from pig slurry waste at high temperature (80 degrees C). Stripping process as pre- or post-treatment to anaerobic digestion has been also evaluated. Treatment performances differ according to pig slurry type. When fresh pig slurry is used, despite working at 80 degrees C, a high initial pH (11.5) is required for complete ammonia removal. On the other hand, for digested pig slurry, complete ammonia removal without pH modification is possible and organic matter significantly less contaminates recovered ammonia salt. Batch anaerobic tests showed that ammonia air stripping is not an advisable pre-treatment to pig slurry anaerobic digestion.

Ammonia↗
PubMed2003

Effect of covering pig slurry stores on the ammonia emission processes.

The aim of this study was to evaluate the effects of different covers (oil, plastic film, perforated polystyrene float, peat and zeolites) on slurry settling characteristics and ammonia emission during storage and following surface application in the field. Laboratory trials were carried out for 15 days using a pilot scale device. Samples of 5 kg slurry were used. At the end of the storage period, distributions of dry matter, pH, total ammoniacal nitrogen and total Kjeldahl nitrogen in slurry were characterized. In the field, ammonia volatilisation was measured for three days using a wind tunnel system. Oil and plastic film retained all ammoniacal nitrogen forms in the slurry, whereas the others reduced ammonia volatilisation by reducing the emitting surface or by adsorbing/absorbing ammonia. Over the whole process studied (storage plus application) ammonia emissions were reduced by 40% by oil up to 65-71% by zeolites with different particle sizes.

Air Pollution↗
PubMed2004

The influence of diet crude protein level on odour and ammonia emissions from finishing pig houses.

Feed trials were carried out to assess the influence of crude protein content in finishing pig diets on odour and ammonia emissions. Eight pigs (4 boars and 4 gilts), average initial weight 70.8 kg (s.e. 3.167) were housed in two pens that were isolated from the rest of a pig house at University College Dublin Research Farm, Newcastle, Dublin, Ireland. Four diets containing 130, 160, 190 and 220 g x kg(-1) crude protein were fed during six four-week feeding periods (one treatment per room). The first week of the feeding periods served to allow odour build up in the pens and as a dietary adjustment period. The pens had partially slatted floors that were cleaned and had all the manure removed after each four-week period. Odour and ammonia concentrations were measured on days 9, 14, 16, 21 and 23 of each trial period. Odour samples were collected in Nalophan bags and analysed for odour concentration using an ECOMA Yes/No olfactometer. The odour threshold concentration was calculated according to the response of the olfactometry panel members and was displayed in Ou(E)m(-3), which referred to the physiological response from the panel equivalent to that elicited by 40 ppbv(-1) n-butanol evaporated in 1 m(3) of neutral gas. Ammonia concentrations in the ventilation air were measured using Dräger tubes. The odour emission rates per animal for the 130, 160, 190 and 220 g x kg(-1) crude protein diets were 12.1, 13.2, 19.6 and 17.6 Ou(E)s(-1)animal(-1), respectively (P<0.01). The odour emission rate per livestock unit (500 kg) for the 130, 160, 190 and 220 g x kg(-1) crude protein diets were 77.6, 80.0, 115.8 and 102.9 Ou(E)s(-1)LU(-1), respectively (P<0.01). The ammonia emission rates per animal for the 130, 160, 190 and 220 g x kg(-1) crude protein diets were 3.11, 3.89, 5.89 and 8.27 g x d(-1)animal(-1), respectively (P 0.05). Manipulation of dietary crude protein levels would appear to offer a low cost alternative, in relation to end-of-pipe treatments, for the abatement of odour and ammonia emissions from finishing pig houses.

Air Pollutants↗
PubMed1999

Mechanism of nitrogen-13-labeled ammonia formation in a cryogenic water target.

Methods for producing N-13 ammonia via the 16O(p,alpha)13N nuclear reaction utilizing a cryogenic target have been investigated. These targets included frozen carbon dioxide and pure frozen water. Results from these targets were compared with the more traditional liquid water target with and without additives. A very dramatic difference was found between the pure water target in the frozen state when compared with the liquid state. When frozen, more than 95% of the nitrogen-13 activity is in the chemical form of ammonia at all radiation doses. In contrast, the liquid water target yielded predominately nitrates and nitrites at high radiation doses. When frozen carbon dioxide was irradiated under these conditions, more than 95% of the nitrogen-13 activity was in the form of nitrate and nitrite. The nitrogen oxides remained on the surface of the target and could be easily removed from the surface with pure water. The wash solution was converted to [13N]ammonia using the DeVarda's alloy method for reduction. It was determined that levels of [13N]ammonia sufficient for diagnostic medical procedures could be produced directly using the frozen water targets or from frozen carbon dioxide with a wet chemical reduction. These results have significance particularly in the design of targetry for low-energy, high-beam current accelerators, because targets of this design can be used with either no vacuum isolation window or a very thin window. The substitution of carbon-13-enriched carbon dioxide for natural carbon dioxide gives access to the 13C(p,n)13N nuclear reaction, which allows protons energies as low as 6 MeV to be used to produce useable quantities of N-13 ammonia. The mechanism of these reactions has been explored to determine why there are such dramatic differences in the product distribution between the frozen state and the liquid or gaseous state.

Ammonia↗
PubMed2003

Structural changes in gills of Lost River suckers exposed to elevated pH and ammonia concentrations.

The Lost River sucker (Deltistes luxatus) is a federally listed, endangered fish that occurs primarily in Upper Klamath Lake-a hypereutrophic lake in southern Oregon, USA. A decline of the sucker population in the lake over the past few decades has been partly attributed to adverse water quality conditions, including elevated pH and ammonia concentrations that occur during summer cyanobacterial blooms. We quantitatively analyzed structural changes in gills of larval Lost River suckers after they were exposed to elevated pH and ammonia concentrations for 30 d. Exposure to pH as high as 10 caused no observed structural changes. However, lamellar thickness and O(2) diffusion distance increased significantly (P<0.05) at ammonia concentrations that did not significantly decrease survival, growth, whole-body ion concentrations, or swimming performance. Additionally, we qualitatively observed increases in the frequency of hyperplasic and hypertrophic mucous cells, tissue damage, epithelial lifting, and infiltration of white blood cells into paracellular lymphatic spaces at the highest sublethal ammonia concentration. These observed gill changes typically indicate compromised respiratory and ionoregulatory capacity, although such effects were not manifested in the assays we performed. Regardless, these structural gill changes appear to be a more sensitive indicator of exposure to elevated ammonia concentrations than are more traditional sublethal indices. Therefore, gill histopathology might be a relevant early-warning monitoring tool of the health of Lost River suckers in Upper Klamath Lake, and other species in similar eutrophic systems.

Ammonia↗
PubMed1995

Effects of intraruminal infusion of propionate on the concentrations of ammonia and insulin in peripheral blood of cows receiving an intraruminal infusion of urea.

To test the hypothesis that propionate can reduce hepatic capacity to detoxify ammonia, effects of the inclusion of propionate in intraruminal infusions of urea on the concentrations of ammonia, other metabolites and insulin in peripheral blood were investigated in two experiments with non-lactating dairy cows. Both experiments were of a 4 x 4 Latin square design with four animals, four treatments and four experimental periods of 7 d; feed was given in two equal meals each day, all intraruminal infusions were given for 1 h at the time of the morning feed, and propionic acid was partly neutralized with NaOH. In Expt 1, the treatments were a basal diet of pelleted lucerne and chopped hay alone or with the following infusions (g/d): urea 80, propionic acid 350, urea 80 plus propionic acid 350. The inclusion of propionate in the urea infusion markedly increased (P < 0.001) the concentration of ammonia in plasma compared with infusion of urea alone. Moreover, the inclusion of urea with the propionate infusion abolished (P < 0.01) the increase in blood insulin level seen with the infusion of propionate alone. In Expt 2, less severe treatments were imposed, the aim being to reproduce metabolic loads of propionate and ammonia that might be expected from a diet of high-protein grass silage rich in lactic acid. The treatments were a basal diet of grass silage alone or with the following infusions (g/d): NaCl 145, NaCl 145 plus urea 50, propionic acid 200, urea 50 plus propionic acid 200. Effects were less pronounced than in Expt 1 but, in the period immediately after infusion, similar effects were seen. It is concluded that propionate-ammonia interactions may have potentially important effects on milk production especially for diets with high proportions of grass silage containing high levels of protein and lactic acid.

Ammonia↗
PubMed2004

Enhanced bromate control during ozonation: the chlorine-ammonia process.

Potentially carcinogenic bromate forms during the ozonation of bromide-containing waters. Some water treatment facilities have had to use ammonia addition and pH depression to minimize bromate formation, but these processes may prove to be insufficient to comply with upcoming regulations. The chlorine-ammonia process (Cl2-NH3), consisting of prechlorination followed by ammonia addition priorto ozonation is shown to cause a 4-fold decrease in bromate formed when compared to the ammonia-only process. Experiments revealed three key mechanisms: (i) oxidation by HOCl of Br- to HOBr and its subsequent masking by NH3 as NH2Br; (ii) decrease of HO- exposure through halogenation of Dissolved Natural Organic Matter (DNOM) by HOCI and scavenging of HO by NH2Cl; and (iii) DNOM acting as a bromine sink after oxidation of Br- to HOBr. At an ozone exposure of 6 mg/L x min and pH 8, conventional ozonation of Lake Zurich water spiked with 560 microg/L Br- formed 35 microg/L BrO3-, whereas the application of the Cl2-NH3 process resulted in 5 microg/L BrO3-. Additional pH depression to pH 6 further decreased bromate formation by a factor of 4. Trihalomethanes (THM) and cyanogen chloride (CNCl), that mayform during prechlorination and monochloramination, respectively, were well below regulatory limits. The chlorine-ammonia process holds strong promise for water treatment facilities struggling with a bromate formation problem during ozonation.

Ammonia↗
PubMed2006

Mitigation of ammonia and hydrogen sulfide emissions by stable aqueous foam-microbial media.

Stable aqueous foam-microbial media consisting of protein-based foams and odor-degrading bacteria were developed to control the emissions of odorous compounds. The optimum foam formulation was determined based on foam characteristics including 50% drainage time, foam lifetime, and foam expansion ratio. When only the aqueous foam was applied onto the surface of a test odor source (i.e., swine manure), ammonia emission was completely suppressed for about 177, 225, 265, 297, and 471 min when the height of foam barrier was 2.5, 5, 10, 15, and 30 cm, respectively. According to the increasing foam height, ammonia emission rates after breakthrough points decreased to 0.16, 0.13, 0.09, 0.07, and 0.02 mg/m3/min, and thus volatilized ammonia concentrations decreased significantly after 600 min. Hydrogen sulfide was similarly suppressed. Ammonia emission was better controlled by incorporating odor-degrading bacteria into the aqueous foam. The odor suppression capacity of the 5-cm foam barrier with microbes was more than eight times greater than that of the barrier only and was similar to that of 30-cm foam barrier without microbes after 1440 min. A significant amount of dinitrogen gas was evolved by the foam-microbial media, indicating a successful biological transformation of ammonia.

Air Pollutants↗
PubMed1998

Anaerobic ammonia oxidation by cell-free extracts of Nitrosomonas eutropha.

Cell-free extracts of Nitrosomonas eutropha oxidized ammonia to nitrite with NO2 (N2O4) as electron acceptor. The ammonia oxidation activity was shown to be sensitive against oxygen. In the absence of oxygen ammonia and NO2 were consumed in a ratio of approximately 1:2 and hydroxylamine occurred as an intermediate. NO was released in amounts equimolar to the consumption of NO2. After passing the cell suspension through a French pressure cell and fractionating it by density gradient centrifugation using a linear sucrose gradient, two soluble and two membrane fractions were detectable. Highest ammonia oxidation activity was measured in the membrane fractions and highest hydroxylamine oxidation activity in the soluble fractions. The KS values of the ammonia oxidizing system in cell-free extracts was about 20 microns NH3 and remained unchanged between pH 7.25 to 8.25.

Ammonia↗
PubMed2001

A comparison of ammonia-oxidiser populations in eutrophic and oligotrophic basins of a large freshwater lake.

A combination of PCR amplification and oligonucleotide probing was used to investigate the populations of ammonia-oxidisers of the beta-Proteobacteria in the eutrophic and oligotrophic basins of Lake Windermere, a large temperate lake in the English Lake District. Numbers of ammonia-oxidisers (MPN) in the Windermere lakewater were low (< 100 cells ml(-1)) throughout the year with the exception of peaks in August, which coincided with stratification, and November in the South Basin where overturn may have introduced ammonia-oxidising bacteria into the water column. Sediment samples contained larger populations of ammonia oxidisers, usually ca. 10(4) per g. dry weight, which remained relatively constant throughout the seasonal cycle in both Basins. DNA was recovered from lakewater and sediment samples and Nitrosospira and N. europaea-eutropha lineage 16S rRNA genes amplified in a nested PCR reaction, with confirmation of identity by oligonucleotide hybridisation. Nitrosospira 16S rDNA was readily detected in all samples and therefore found to be ubiquitous. In contrast, nitrosomonad DNA of the N. europaea-eutropha lineage could only be detected in the oligotrophic North Basin. Enrichment cultures of lakewater samples only exhibited nitrification at low (0.67 mM) and medium (5 mM) ammonium concentrations, whilst sediment enrichments nitrified at all concentrations tested including high (12.5 mM) ammonium medium. These data suggest that ammonia-oxidiser populations may be physiologically distinguished between lakewater and sediment, and that species distribution in a single lake is non-uniform.

Ammonia↗
PubMed2001

Effects of gaseous NO2 on cells of Nitrosomonas eutropha previously incapable of using ammonia as an energy source.

Cells of Nitrosomonas eutropha grown under anoxic conditions with hydrogen as electron donor and nitrite as electron acceptor were initially unable to oxidize ammonia (ammonium) and hydroxylamine when transferred to oxic conditions. Recovery of ammonia and hydroxylamine oxidation activity was dependent on the presence of NO2. Under oxic conditions, without addition of NO2, ammonia consumption started after 8 - 9 days, and small amounts of NO and NO2 were detectable in the gas atmosphere. Removing these nitrogen oxides by intensive aeration, ammonia oxidation activity decreased and broke off after 15 days. Addition of gaseous NO2 (25 ppm1) led to a fast recovery of ammonia oxidation (3 days). Simultaneously, the arrangement of intracytoplasmic membranes (ICM) changed from circular to flattened vesicles, the protein pattern revealed an increase in the concentration of a 27 and a 30 kDa polypeptide, and the cytochrome c content increased significantly.

Aerobiosis↗
PubMed2002

An attempt to decrease ammonia levels after portacaval anastomosis in dogs: hepatic periarterial neurectomy.

Hepatic encephalopathy and elevated serum ammonia levels occur commonly after portacaval shunt and are hypothesized to be, in part, due to decreased hepatic blood flow. Prior work has demonstrated increased blood flow to the liver following hepatic periarterial neurectomy. In this experimental study, we investigated the functional, hemodynamic, and histopathological changes in the liver and kidney occurring after the addition of hepatic periarterial neurectomy to side-to-side portacaval shunt in dogs. It is our hypothesis that the addition of hepatic periarterial neurectomy to portacaval shunt will decrease postshunt ammonia levels. Side-to-side portacaval shunt was performed in 12 dogs (group I). Hepatic periarterial neurectomy was added to portacaval shunt in 9 dogs (group II). Serum levels of ammonia, urea, creatinine, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, albumin, and bilirubin together with hepatic blood flow were determined in both groups preoperatively and on postoperative day 21. The pre- and postoperative histopathologic changes of the liver and kidney were evaluated. There was significantly less postoperative elevation of serum ammonia and aspartate aminotransferase when hepatic periarterial neurectomy was added to the portacaval shunt procedure. Hemodynamic studies of hepatic artery and hepatic tissue indicated better blood flow in group II. The histopathologic evaluation of group II showed expansion of sinusoids, portal vessels, and portal areas and increased portal fibrosis as compared to group I. The results of this experimental study show that adding hepatic periarterial neurectomy to the portacaval shunt procedure improves postoperative serum levels of ammonia and aspartate aminotransferase and hepatic artery and tissue blood flow.

Ammonia↗
PubMed1998

Nitroarginine, an inhibitor of nitric oxide synthase, prevents changes in superoxide radical and antioxidant enzymes induced by ammonia intoxication.

Injection of large doses of ammonium salts leads to the rapid death of animals. However, the molecular mechanisms involved in ammonia toxicity remain to be clarified. We reported that injecting ammonium acetate (7 mmol/kg) to rats increases the production of superoxide and reduces the activities of some antioxidant enzymes in rat liver and brain. We proposed that these effects induced by ammonia intoxication would be mediated by formation of nitric oxide. To test this possibility we tested whether injection of nitroarginine, an inhibitor of nitric oxide synthase, prevents the effects of ammonia intoxication on antioxidant enzymes and superoxide formation. Following injection of ammonia, glutathione peroxidase, superoxide dismutase and catalase activities were decreased in liver by 42%, 54% and 44%, respectively. In brain these activities were reduced by 35%, 46% and 65%, respectively. Glutathione reductase remained unchanged. Superoxide production in submitochondrial particles from liver and brain was increased by more than 100% in both tissues. Both reduction of activity of antioxidant enzymes and increased superoxide radical production were prevented by previous injection of 45 mg/kg of nitroarginine, indicating that ammonia induces increased formation of nitric oxide, which in turn reduces the activity of antioxidant enzymes, leading to increased formation of superoxide.

Ammonia↗
PubMed1977

Relationship of renal ammonia production and potassium homeostasis.

Renal ammonia production appears to be intimately related to potassium homeostasis, and the two may comprise the components of a closed loop regulatory system. Studies with both intact organisms and in vitro systems indicate that potassium depletion stimulates and chronic potassium-loading suppresses renal ammonia production. An increase in ammoniagenesis has been shown to decrease potassium excretion. These observations suggest that changes in potassium modulate ammonia production, which in turn maintains hydrogen ion homeostasis and influences potassium excretion. Potassium depletion increases rat renal cortical ammonia production by altering metabolism in fashion identical to metabolic acidosis, but there is no convincing evidence that both processes are mediated by similar changes in either cellular hydrogen ion or potassium concentration. By contrast, potassium-loading, which depresses ammonia production, appears to affect primarily the outer medulla, a region that is not influenced by potassium depletion. Thus, potassium-loading apparently affects different portions of the renal tubule than depletion does, but the specific mechanism and physiologic significance of the different sites of action is unknown.

Ammonia↗