High Concentrations Of Ammonium Ions Research Articles

Chemical Fractionation Modeling of Plumes Indicates a Gas-rich, Moderately Alkaline Enceladus Ocean

Enceladus harbors an ocean beneath its ice crust that erupts spectacular plumes from fissures at the south pole. The plume composition was measured by the Cassini spacecraft, and provides evidence for the ocean’s gas content, salinity, pH, and potential for life. Understanding the ocean’s composition is complicated by physicochemical processes that alter the plume composition during eruption, such as water vapor condensation in the icy fissures and gas exsolution from the ocean surface. We developed a model that includes key fractionation processes, in particular fractionation during gas exsolution, which has not been previously considered. Our model predicts a moderately alkaline (pH 7.95–9.05), gas-rich ocean (∼10−5–10−3 molal) with high concentrations of ammonium ions (10−2–10−1 molal). Our derived dissolved gas concentrations are higher than in recent studies because we account for gas exsolution, which depletes gases in the plume compared to the ocean, and because our model conserves mass flow rates between gas exsolution from the ocean and eruption from the tiger stripe fissures. We find carbon dioxide and hydrogen concentrations that could provide sufficient chemical energy for oceanic life in the form of hydrogenotrophic methanogens. Carbon dioxide concentrations of 10−5–10−3 molal indicate a more Earth-like pH than the pH ∼8.5–13.5 in previous studies. The inferred bulk ammonium and total inorganic carbon concentrations are consistent with cometary levels. This corroborates evidence from cometary deuterium-hydrogen (D/H) ratios that Enceladus formed from comet-like planetesimals. Our results suggest a gas-rich ocean that inherited its high volatile concentrations from comet-like building blocks.

Chemical and ecological quality of water and bottom sediments in small rivers of Belgorod oblast

Belgorod Oblast has limited water resources. The paper explores the chemical and ecological characteristics of water and bottom sediments in the Oskol River tributaries. In samples of water taken from small rivers, Maximum Allowable Concentrations (MAC) for pollutants was excessive, including suspended matter, ammonium ions, nitrite ions, phosphate ions, BOD5 and mineral elements. A hydrochemical water pollution index (WPI6) ranges from 1.0 to 1.9, which characterizes water bodies in the categories from clean to moderately polluted watercourses. A comparatively high WPI6 index is recorded in summer for the Kotel River – 1.4, for the Belenkaya River – 2.3, which is attributed to a high concentration of ammonium ions, nitrites and phosphates found to be present in the water. This indicates recent pollution and a changing trophic status of the reservoir. The amount of metals in river water exceeds the MAC norms: for iron – 1.7 -6 MAC; for copper – 1.6 - 8 MAC; for manganese – 0.8 - 22 MAC; for zinc – 1.9 - 9.9 MAC. Concentrations of micronutrients are subject to significant seasonal fluctuations. No excess of lead is found to be present in surface waters. In the samples of bottom sediments taken from the Oskol River tributaries, no excess of MAC values is found, except for lead (1.1 - 2.9 MAC), manganese (1.6 - 2.2 MAC), copper (1.2 - 1.6 MAC) and phosphate ions (1.3 - 2.3 MAC). It is obvious that the sources of pollution for small rivers are runoffs from agricultural land, livestock farms and household wastewater of nearby settlements.

The state of Cu2+ ions in concentrated aqueous ammonia solutions of copper nitrate

Stabilization of Cu2+ ions in concentrated aqueous ammonia solutions of copper nitrate in a wide range of ammonium ion concentrations has been studied by EPR and electronic absorption spectroscopy. Three types of Cu2+ associates with different types of orbital ordering have been identified. The ammonium ion concentration in a solution has a decisive effect on the type of orbital ordering of Cu2+ ions in associates. In all cases, Cu2+ ordering in associates is caused by the existence of bridging OH groups in the axial and equatorial positions of [Cu(NH3)n(H2O)6 − n]2+ complexes (n < 6). At a high concentration of ammonium ions, weakly bound associates of tetramminecopper with the \(d_{x^2 - y^2 }\) ground state are formed. In solutions with low ammonium concentrations, bulky associates with the \(d_{y^2 }\) and \(d_{x^2 - z^2 }\) ground states and associates of Cu2+ ions with the \(d_{x^2 - y^2 }\) ground state with hydroxyl groups in the equatorial plane and axial water molecules are formed.

Comparative Effects of Nitrogen Fertigation and Granular Fertilizer Application on Growth and Availability of Soil Nitrogen during Establishment of Highbush Blueberry

A 2-year study was done to compare the effects of nitrogen (N) fertigation and granular fertilizer application on growth and availability of soil N during establishment of highbush blueberry (Vaccinium corymbosum L. “Bluecrop”). Treatments included four methods of N application (weekly fertigation, split fertigation, and two non-fertigated controls) and four levels of N fertilizer (0, 50, 100, and 150 kg·ha−1 N). Fertigation treatments were irrigated by drip and injected with a liquid urea solution; weekly fertigation was applied once a week from leaf emergence to 60 d prior to the end of the season while split fertigation was applied as a triple-split from April to June. Non-fertigated controls were fertilized with granular ammonium sulfate, also applied as a triple-split, and irrigated by drip or microsprinklers. Weekly fertigation produced the smallest plants among the four fertilizer application methods at 50 kg·ha−1 N during the first year after planting but the largest plants at 150 kg·ha−1 N in both the first and second year. The other application methods required less N to maximize growth but were less responsive than weekly fertigation to additional N fertilizer applications. In fact, 44–50% of the plants died when granular fertilizer was applied at 150 kg·ha−1 N. By comparison, none of the plants died with weekly fertigation. Plant death with granular fertilizer was associated with high ammonium ion concentrations (up to 650 mg·L−1) and electrical conductivity (>3 dS·m−1) in the soil solution. Early results indicate that fertigation may be less efficient (i.e., less plant growth per unit of N applied) at lower N rates than granular fertilizer application but is also safer (i.e., less plant death) and promotes more growth when high amounts of N fertilizer is applied.

Prevention of Progressive Mask Defects through Residual Ammonium and Sulfuric Ion Control

Progressive defect generation has been a serious issue in wafer lithography, as illumination wavelength becomes shorter with the introduction of the 248 and 193 nm wavelengths. Several research groups have reported that cleaning residues, mostly ammonium and sulfate ions, on a mask surface are critical sources of progressive defect generation. A new cleaning process has been developed and studied to minimize progressive defect generation sources. The new cleaning process consists of dehydration baking, dry etching, and H2O2 treatment. Dehydration baking was proposed to reduce the concentration of sulfate residues while H2O2 treatment and dry etching are proposed to control ammonium ions. Dehydration baking is employed at 230 °C for 600 s to reduce the sulfate ion concentrations from 32 to 1.6 ppb on chrome on glass (COG) or binary intensity mask (BIM). ArF embedded attenuate phase shift mask (EAPSM) is associated with a high concentration of ammonium ions (>5000 ppb), and is easily susceptible to progressive defect generation under ArF illumination. More than 90% ammonium extraction (removal) efficiency was achieved by H2O2 treatment for ArF EAPSM. Moreover, the optimized new cleaning process has reduced the concentration of ammonium ions up to 50 ppb compared with the 1500 ppb reported by conventional RCA cleaning in ArF EAPSM. In a strictly controlled sulfate environment (less than 6 ppb), threshold defect energy has improved from 25 to 100 kJ by reducing the concentration of ammonium ions down to 45 ppb and below. Therefore, the concentration of residual ammonium ions along with residual sulfate ions should be strictly controlled to improve wafer and photomask yields.

Response of 19 Azolla strains to a high concentration of ammonium ions

The response of 19 Azolla strains from five species to 20 mM ammonium ions was examined. The response varied even among strains of the same species. The tolerance indexes of both relative growth rate and nitrogen fixation [(values for plants grown in the presence of ammonium ions)/(values for plants grown in the absence of ammonium ions)] showed that ammonium ions did not always simultaneously inhibit growth and nitrogen fixation of individual strains. The tolerance of each Azolla–Anabaena association to ammonium ions is assumed to be determined separately by both the host fern and the symbiotic Anabaena. The inhibitory effects of ammonium appeared predominantly in the mature region of Azolla–Anabaena associations. In the sensitive strains, both chlorophyll content and the number of cyanobionts were reduced only in the mature region when ammonium ions were present. Possible strains for treatment of wastewater, which contains a high concentration of ammonium ions, are discussed.

Metabolic Characteristics of the Mutant Yarrowia lipolytica Strain 1 Producing α-Ketoglutaric and Citric Acids from Ethanol and the Effect of [NH+4] and [O2] on Yeast Respiration and Acidogenesis

The comparative studies performed in this work showed that overproduction of α-ketoglutaric acid (KGA) and citric acid (CA) from ethanol by the mutantYarrowia lipolyticastrain 1 requires both a deficiency of thiamine and a relatively high concentration of ammonium ions in the medium, whereas CA overproduction requires an almost zero concentration of ammonium ions. The threshold value of the dissolved oxygen concentration in the medium, pO2, for CA overproduction is considerably higher than for KGA overproduction. The respiration rate of CA-overproducing cells was 2–3.5 times higher than that of KGA-overproducing cells. The main terminal electron carrier functioning in the KGA-overproducing cells was cytochrome oxidase. In the CA-overproducing cells, the main terminal oxidase was presumably o-type cytochrome.

New aerobic ammonium-dependent obligately oxalotrophic bacteria: description of Ammoniphilus oxalaticus gen. nov., sp. nov. and Ammoniphilus oxalivorans gen. nov., sp. nov.

The genus Ammoniphilus is proposed for aerobic endospore-forming Gram-variable rod-shaped bacteria, which are ammonium-dependent, obligately oxalotrophic and haloalkalitolerant, oxidase- and catalase-positive, mesophilic and motile by peritrichous flagella. Cell wall contained two electron-dense layers. The external layer consists of a chain of electron-dense granules morphologically resembling the cellulosomes of Clostridium thermocellum. Two species are described, Ammoniphilus oxalaticus gen. nov., sp. nov. and Ammoniphilus oxalivorans gen. nov., sp. nov. The type strains of these species are strains RAOx-1 (= DSM 11538) and RAOx-FS (= DSM 11537), respectively. Ammoniphilus strains were isolated from the rhizosphere of sorrel (Rumex acetosa) and from decaying wood. The strains require a high concentration of ammonium ions and use oxalate as the sole organic source of carbon and energy for growth; no growth factors were required. Growth occurred at pH 6.8-9.5. The optimum temperature and pH for growth were 28-30 degrees C and 8.0-8.5. All strains grew in a saturated solution of ammonium oxalate, and tolerated 3% NaCl. Whole-cell hydrolysates contain meso-diaminopimelic acid and glucose. The menaquinone of the strains was MK 7, and the major cellular fatty acids were 12-methyl tetradecanoic, cis-hexadec-9-enoic and hexadecanoic acids. The G + C content of the DNA was 45-46 mol% for A. oxalaticus and 42 mol% for A. oxalivorans. The almost complete 16S rDNA sequence of three strains of the two species of Ammoniphilus shows that the genus falls into the radiation of the Clostridium-Bacillus subphylum of Gram-positive bacteria. The closest phylogenetic neighbour of Ammoniphilus is Oxalophagus oxalicus. The DNA-DNA hybridization value between strains RAOx-1 and RAOx-FS was 39.7%.

Aspartate aminotransferase and tylosin biosynthesis in Streptomyces fradiae

Aspartate aminotransferase as well as valine dehydrogenase and threonine dehydratase was required for the biosynthesis of tylosin in Streptomyces fradiae NRRL 2702. The biosynthesis of these enzymes and tylosin production were repressed by high concentrations of ammonium ions. The change in specific tylosin production rates in batch cultures with different initial concentrations of ammonium ions showed patterns similar to those of the specific production rates of aspartate aminotransferase, valine dehydrogenase, and threonine dehydratase. Aspartate aminotransferase has been purified by acetone precipitation, DEAE-cellulose, hydroxyapatite, and preparative electrophoresis chromatographies. The purified enzyme (120 kDa) consisted of two subunits identical in molecular mass (54 kDa) and showed homogeneity, giving one band with a pI of 4.2 upon preparative isoelectric focusing. The enzyme was specific for L-aspartate in the forward reaction; the Km values were determined to be 2.7 mM for L-aspartate, 0.7 mM for 2-oxyglutarate, 12.8 mM for L-glutamate, and 0.15 mM for oxaloacetate. The enzyme was somewhat thermostable, having a maximum activity at 55 degrees C, and had a broad pH optimum that ranged from 5.5 to 8.0. The mode of action was a ping-pong-bi-bi mechanism.

High Concentrations of Ammonium Ions at Low pH Decrease the Number of Cyanobionts in Apical Portions of &lt;italic&gt;Azolla&lt;/italic&gt;

When Azolla plants (Azolla filiculoides vax.japonica) were grown in media with high concentrations of ammonium ions at pH 3.5, numbers of cyanobionts in apical portions were very much reduced. Microscopic observations revealed that cyanobionts in these plants were preferentially damaged, with resultant death and lysis.

Futile cycling of ammonium ions via the high affinity potassium uptake system (Kdp) of Escherichia coli

Escherichia coli Frag1 was grown under various nutrient limitations in chemostat culture at a fixed temperature, dilution rate and pH both in the presence and the absence of a high concentration of ammonium ions by using either ammonium chloride or DL-alanine as the sole nitrogen source. The presence of high concentrations of ammonium ions in the extracellular fluids of potassium-limited cultures of E. coli Frag1 caused an increase of the specific rate of oxygen consumption of these cultures. In contrast, under phosphate-, sulphate- or magnesium-limited growth conditions no such increase could be observed. The presence of high concentrations of ammonium ions in potassium-limited cultures of E. coli Frag5, a mutant strain of E. coli Frag1 which lacks the high affinity potassium uptake system (Kdp), did not increase the specific rate of oxygen consumption. These results indicate that ammonium ions, very similar to potassium ions both in charge and size, are transported via the Kdp leading to a futile cycle of ammonium ions and ammonia molecules (plus protons) across the cytoplasmic membrane. Both the uptake of ammonium ions and the extrusion of protons would increase the energy requirement of the cells and therefore increase their specific rate of oxygen consumption. The involvement of a (methyl)ammonium transport system in this futile cycle could be excluded.

Taurine release from brain slices in thioacetamide-induced hepatic encephalopathy in rats

The possible involvement of taurine in the pathogenesis of hepatic encephalopathy was studied in rats injected with thioacetamide. Spontaneous release of exogenous labeled taurine was not affected in any brain area studied, but the potassium-stimulated release was enhanced in the striatum in thioacetamide-treated rats. High concentrations of ammonium ions also evoked greater release of taurine from striatal slices in rats with thioacetamide-induced hepatic encephalopathy.

Structure spatiale des sels nutritifs au sein d'un ecosysteme lagunaire: l'etang de thau

The present studies were undertaken to assess the geographical distribution of the nutritive richness in the Thau lagoon (Hérault, France). Three descriptors of nutrients in this ecosystem were studied: ammonium, nitrates and phosphates. A systematic sampling strategy was adopted (Frontier, 1983): 63 sampling points described the lagoon; the distance between two contiguous sampling points was 1 km (Fig. 1). The variables were evaluated at each point, during 1 year, at four sampling periods. Analytical methods for nutrient determination were described by Aminot and Chaussepied (1983) and Parsons et al. (1984). The automatic procedure for nitrates and phosphates determination proposed by Tréguer and Lecorre (1975) was used. The following statistical methods were applied: 1. (1) descriptive statistics for each period 2. (2) contiguous grouping linked to: ◦ - hierarchical classification, the similarity between the two points was calculated by the Gower coefficient (Legendre and Legendre, 1984); ◦ - k is a classification method using the later partition as an initial one. Both programs using these computations were part of an R package (Legendre, 1985) 3. (3) discriminant analysis for testing geographical zones obtained by grouping methods (Romeder, 1973). The stepwise discriminant analysis gives the most discriminant period in the different groups. The neighbor discriminant procedure indicates the percent of well-classified sampling points. Statistical characterization of periods for nitrates is shown in Table 1. The two winter periods have high nitrate concentrations. Grouping methods give seven geographical zones (Fig. 2). Statistical characterization of these zones is indicated in Table 2. The most discriminant period for this zonation is February (Table 3), June was not included. February explains 70% of well-classified sampling points (Table 4). Combining February with other periods explains specific groups, i.e. group 4 is confirmed by adding the May period and group 1 by adding the October period. The zonation results from two gradients due one to winter nitrates inflow, and one to summer nitrates consumption. Four sampling points were never well-classified, because of the geographical constraint. Statistical characterization of periods for ammonium ion is given in Table 5. As for nitrates, the two winter periods have high ammonium ion concentrations and summer periods have low ammonium ion concentrations. Grouping methods give six geographical zones (Fig. 3). Statistical characterization of these zones is given in Table 6. The correlation coefficients of the four periods are approximately equal (Table 7), therefore the combination of the four periods give a very good percent of well-classified sampling points (Table 8). October period explains group 2, May period group 4 and February period confirms the percent of groups 1 and 3 given by the June period. For ammonium ion, discriminant analysis shows the contribution of the four periods, each period has a different gradient concentration due to different ecological phenomena (sediment release, inflow, consumption, regeneration). Eleven sampling points are never well classified (Fig. 3), they are on groups borders. Statistical characterization of periods for phosphates is given in Table 9. Grouping methods give five geographical zones (Fig. 4). Statistical characterization of these zones is given in Table 10. The correlation coefficients of the four periods are high (Table 11). Table 12 shows that only group I has always a high percent of well-classified sampling points. The geographical zonation of phosphates seems inadequate. The data collected during 1 year, analysed by classification methods, gave the spatial structure of the lagoon appropriate to any period. Our studies showed different spatial distribution for the three nutrients during 1 year. An attempt was made to link these spatial patterns to environmental changes. In addition the discriminant analysis revealed three kinds of singular sampling points: • - located on the lagoon border • - located between two adjacent groups • - located near waste water treatment plant.

N-Acetyl-6-hydroxytryptophan oxidase, a developmentally controlled phenol oxidase from Aspergillus nidulans

We have purified a specific phenol oxidase which is produced during conidiophore development in the fungus Aspergillus nidulans. Two active forms (A and B) have molecular masses of 50 and 48 kDa respectively; they have identical N-termini (24 residues). We have analysed the metal ion content of the B form; it is unusual in consisting of one zinc and two copper atoms per molecule. A temperature-sensitive mutant (ivoB192) produces a thermolabile enzyme, implying that ivoB is the structural locus. The natural substrate of the enzyme is N-acetyl-6-hydroxytryptophan, but it can be assayed colorimetrically or polarographically using hydroquinone monomethyl ether (HME) as substrate. It will also oxidize p-cresol, but not tyrosine, 3,4-dihydroxyphenylalanine or o-methoxyphenol. Colour development with HME substrate is strongly enhanced by high ammonium ion concentrations. Activity against HME is inhibited by 2,3-dihydroxynaphthalene, phenylhydrazine, diethyl dithiocarbamate and 8-hydroxyquinolene.

Evaluation of the Jokoo‐ION 150 AC: Guidelines for the evaluation of analysers by ion‐selective electrodes

The Jokoo-ION 150 AC is an automatic sodium, potassium and chloride analyser which uses ion-selective electrodes. The sample mode can be whole-blood, serum or urine. To evaluate a urine sample, a previous dilution (1:6) with the standard 1 solution is required. For three concentrations of control materials, the total precision (CV) ranged from 0.17 to 1.22% for sodium, 0.22 to 1.69% for potassium and 0.16 to 0.74% for chloride. The system demonstrated acceptable performance in detection limit, linearity, drift and carry-over. Patients' results from ION 150 AC correlated well with those from a SMAC II and an IL 943. In a study on potential interferences, a slightly negative interference with potassium was found with increases in lithium; and only high ammonium ion concentrations caused a positive interference on the potassium ion. A slightly positive interference of bromide on the chloride ion was also found. The electrode slope, electrode response, sample temperature and pH effect, effects of high concentrations of proteins or lipids, and haematocrit influence on the sodium, potassium and chloride ion concentration were also evaluated. The strategy adopted in this study provides an ideal framework for future evaluations of ionselective electrode analysers.

Effect of ammonium ions on the composition of fatty acids inStreptomyces fradiae, producer of tylosin

The regulation of fatty acid composition by ammonium ions and amino acids was studied in Streptomyces fradiae, a tylosin producer. The quantity of branched-chain fatty acids in S. fradiae cells decreased significantly in cultures cultivated in a medium containing high concentrations of ammonium ions, in which the biosynthesis of tylosin was also strongly inhibited. Amino acids stimulating the tylosin production most pronouncedly, also substantially modified the composition of cell fatty acids.

Influence of ammonium on the biosynthesis of the macrolide antibiotic tylosin

The effect of ammonium ions on growth and tylosin biosynthesis in Streptomyces fradiae NRRL 2702 cultured on a chemically defined medium was studied. Mycelial growth and tylosin production were not affected when ammonium sulphate was added to idiophase cultures to a final concentration of 10 m m or 20 m m; however, when ammonium sulphate was added to tylosin cultures to a final concentration of 20 m m before the onset of antibiotic biosynthesis (trophophase), tylosin production was severely suppressed while mycelial growth was stimulated. The activities of propionyl-coenzyme A carboxylase (EC 6.4.1.3) and methylmalonyl-coenzyme A carboxyltransferase (EC 2.1.3.1), enzymes involved in the synthesis of tylonolide precursors, were depressed in high ammonium cultures. The activity of macrocin 3′- o-methyltransferase, which catalyses the methylation of macrocin to form tylosin, was also affected by high concentrations of ammonium ions added in the trophophase.

Super Squid Lies in State

It The giant squid in legends grabs sailors and clutches hapless ships; in real life it seldom comes to surface of sea. But visitors to Smithsonian Institution's Museum of Natural History can now view a 450pound preserved in 125 gallons of alcohol. Clyde F. E. Roper, Smithsonian zoologist who studies squid and its other cephalopod relatives octopi, cuttlefish and chambered Nautili says Smithsonian is the only U. S. museum with an actual specimen of giant squid on display. The particular giant squid that is on display was washed ashore on Plum Island off coast of Massachusetts in February 1980. It was first giant squid to be found stranded on a U.S. beach in 20 years. Tossed about by waves, squid's two long feeding tentacles and most of arm tips were broken off, and much of its maroon-colored skin was rubbed away. But otherwise still 12 feet long and with 10-inch-diameter eyes intact, is in very good shape, Roper says. Scientists surmise that this squid was half-grown at time of its death, only about 30 feet long. The largest giant squid are 60 feet, tip of tentacles to tip of tail. It took four men to carry squid off Plum Island beach on a stretcher. Then specimen was displayed at New England Aquarium in Boston before being moved to Smithsonian. After it is displayed in Washington for a year, Roper plans to dissect giant squid to learn more about its anatomy. We have a tremendous number of unanswered questions about giant he says. Roper estimates there are millions of giant squid in oceans, and number is probably increasing as population of whales, which eat giant squid, decreases. But they are seldom caught in fishing nets, so there are only about a hundred specimens or parts available to scientists. Most of these specimens were washed ashore, dying or dead. Others were picked up as they floated on ocean surface or were removed from stomachs of stranded sperm whales. Roper believes it unlikely that a giant squid will soon be captured alive or observed in its natural habitat, so those who study creatures must make do with rare remains. Our objective [in displaying specimen] is to try to show people that giant squid are real, Roper says. Biology is more interesting than fables. Although myths of monstrous animals are exaggerated, these animals truly are giants, he says. Adults are 60 times length and 1,000 times weight of commonplace squid, which are served Italian-style as calamari and Japanesestyle as ika (for example in a type of sushi). Roper reports from bitter experience that taste of giant squid is chiefly that of ammonia. Subsequent to that disappointment, he discovered buoyancy of heavy animal is due to high concentration of ammonium ions in its muscles. When Smithsonian's giant squid specimen goes off display, Roper plans to map digestive, circulatory and reproductive systems. haven't been worked out before, he says. He and colleagues also hope to learn what animal ate, its sex and state of maturity and whether it harbored any parasites. They plan to do dissection so that outer form of specimen remains intact, and it may continue to fill previous gap in Smithsonian's cephalopod collection. Meeting with reporters day before squid went on display, and day of President Reagan's State of Union address, Roper was asked to describe the state of squid. His squid assessment was far more positive than Reagan's national one. It's fabulous, a wonderful specimen, Roper replied. It's valuable both scientifically and for public. D E

Influence of contamination on the analysis of precipitation samples

Liquid precipitation samples, collected in a standard open gauge, are often contaminated by biological debris, which can give rise to unusually high ammonium ion concentrations. In order to prevent this kind of contamination a 1-mm fibreglass teflon coated grid was mounted in the neck of the collection bottle. Collection characteristics of this gauge were compared with a standard open gauge by a parallel sampling of precipitation in the two gauges. 34 parallel samples were collected during 6 months (May–October. 1979) in a rural area. The results indicate that biological contamination has no effect on the concentration of chloride, nitrate, and sulphate ion in the liquid precipitation samples. As expected, biological contamination has a very strong influence on concentrations of ammonium ion, strong acid, and on pH.

The role of tetraalkylammonium salts in the electro‐reduction of ketones. Part II: The reduction of acetophenone in an aprotic environment

AbstractA polarographic study of the electro‐reduction of acetophenone in dry acetonitrile has revealed that under strictly anhydrous conditions the carbonyl compound can be reduced only if tetraalkylammonium ions are present. The role played by these ammonium ions is discussed. It is concluded that the catalytic effect of the ammonium ions has to be related to an increased polarization of the carbonyl double bond being induced during collision of the ammonium ions with the carbonyl compound. At high ammonium ion concentrations, however, the effect of this catalysis becomes smaller due to preferential adsorption of the ammonium ions on the electrode surface, as a result of which the carbonyl compound is displaced from the direct vicinity of the electrode.