Ammonium sulfate

About: Ammonium sulfate is a research topic. Over the lifetime, 7913 publications have been published within this topic receiving 107703 citations. The topic is also known as: ammonium sulphate & (NH4)2SO4.

Organics alter hygroscopic behavior of atmospheric particles

Abstract: The optical and chemical properties of atmospheric particles and their ability to act as cloud condensation nuclei (CCN) depend strongly upon their affinity for water. Laboratory experiments have shown that water soluble substances such as ammonium sulfate, ammonium nitrate, and sodium chloride, which are major inorganic components of atmospheric particles, absorb water in an amount proportional to water vapor pressure. Analogous information about the interactions between water and organics, which are another major component of atmospheric particles, is lacking. Here we analyze concurrent observations of particle chemical composition and water content from a continental nonurban (Grand Canyon) and an urban (Los Angeles) location to determine whether the water content of atmospheric particles is influenced by the presence of organics. By comparing the observed water content with the water content expected to be associated with the inorganic fraction, we find that the aggregate hygroscopic properties of inorganic particles are altered substantially when organics are also present. Furthermore, the alterations can be positive or negative. For the nonurban location, organics enhance water absorption by inorganics. In the relative humidity (RH) range of 80–88% organics account for 25–40% of the total water uptake, on average. For the urban location, on the other hand, the net effect of organics is to diminish water absorption of the inorganics by 25–35% in the RH range of 83–93%.

Methane and nitrous oxide emissions from rice paddy fields as affected by nitrogen fertilisers and water management

Abstract: Methane and N2O emissions affected by nitrogen fertilisers were measured simultaneously in rice paddy fields under intermittent irrigation in 1994. Ammonium sulphate and urea were applied at rates of 0 (control), 100 and 300 kg N ha-1. The results showed that CH4 emission, on the average, decreased by 42 and 60% in the ammonium sulphate treatments and 7 and 14% in the urea treatments at rates of 100 and 300 kg N ha-1, respectively, compared to the control. N2O emission increased significantly with the increase in the nitrogen application rate. N2O emission was higher from ammonium sulphate treatments than from the urea treatments at the same application rate. A trade-off effect between CH4 and N2O emission was clearly observed. The N2O flux was very small when the rice paddy plots were flooded, but peaked at the beginning of the disappearance of floodwater. In contrast, the CH4 flux peaked during flooding and was significantly depressed by mid-season aeration (MSA). The results suggest that it is important to evaluate the integrative effects of water management and fertiliser application for mitigating greenhouse gas emissions in order to attenuate the greenhouse effect contributed by rice paddy fields.

A three-dimensional model of the global ammonia cycle

Abstract: Using a three-dimensional (3-D) transport model of the troposphere, we calculated the global distributions of ammonia (NH3) and ammonium (NH 4 + ), taking into account removal of NH3 on acidic aerosols, in liquid water clouds and by reaction with OH. Our estimated global 10°×10° NH3 emission inventory of 45 Tg N-NH3 yr− provides a reasonable agreement between calculated wet NH 4 + deposition and measurements and of measured and modeled NH 4 + in aerosols, although in Africa and Asia especially discrepancies exist. NH3 emissions from natural continental ecosystems were calculated applying a canopy compensation point and oceanic NH3 emissions were related to those of DMS (dimethylsulfide). In many regions of the earth, the pH found in rain and cloud water can be attributed to acidity derived from NO, SO2 and DMS emissions and alkalinity from NH3. In the remote lower troposphere, sulfate aerosols are calculated to be almost neutralized to ammonium sulfate (NH4)2SO4, whereas in the middle and upper troposphere, according to our calculations, the aerosol should be more acidic, as a result of the oxidation of DMS and SO2 throughout the troposphere and removal of NH3 on acidic aerosols at lower heights. Although the removal of NH3 by reaction with the OH radical is relatively slow, the intermediate NH2 radical can provide a substantial annual N2O source of 0.9 −0.4 +0.9 Tg, thus contributing byca. 5% to estimated global N2O production. The oxidation by OH of NH3 from anthropogenic sources accounts for 10% of the estimated total anthropogenic sources of N2O. This source was not accounted for in previous studies, and is mainly located in the tropics, which have high NH3 and OH concentrations. Biomass burning plumes, containing high NO x and NH3 concentrations provide favourable conditions for gas phase N2O production. This source is probably underestimated in this model study, due to the coarse resolution of the 3-D model, and the rather low biomass burning NH3 and NO x emissions adopted. The estimate depends heavily on poorly known concentrations of NH3 (and NO x ) in the tropics, and uncertainties in the rate constants of the reactions NH2 + NO2 → N2O + H2O (R4), and NH2 + O3 → NH2O + O2 (R7).

A Critical Evaluation of the Nitrogen Assimilation Tests Commonly Used in the Classification of Yeasts

Abstract: The ability of some groups of closely related yeasts to use potassium nitrate as a source of nitrogen was applied successfully by Stelling-Dekker (1931) to the classification of the sporogenous yeasts. Later, Lodder (1934) added other nitrogen compounds, namely, ammonium sulfate, urea, asparagine, and peptone, in diagnostic tests for her classification of the nonsporogenous, nonfilamentous yeasts. She employed a modification of Beijerinck's (1889) auxanographic technique in the following manner: About 2 ml of a dense suspension of the yeast to be tested were placed in a petri dish. It was assumed on the basis of Wildiers' (1901) work that the use of such a heavy inoculation of cells would provide adequate growth factors. An agar medium consisting of 2 per cent glucose, 0.1 per cent potassium dihydrogen phosphate, 0.05 per cent magnesium sulfate, and 2.0 per cent washed agar was cooled to 40 C and poured into the dish. The medium and yeast were quickly mixed. After the medium had solidified, the plate was placed in an incubator to dry for a few hours at 30 C. Then small portions of the nitrogen-containing compounds were placed on the solid surface of the inoculated agar. On incubation at 25 C, an area of growth was produced around those compounds that were assimilated. Lodder's study disclosed that a majority of the yeasts with which she worked were capable of utilizing all the compounds that she had introduced. However, some species of Torulopsis and all species of Kloeckera failed to assimilate ammonium sulfate, urea, and asparagine. These facts were subsequently incorporated in her descriptions of species and genera. These nitrogen compounds, as well as the use of the auxanographic plate method, were generally adopted for diagnostic purposes by succeeding workers in Europe and South America. Langeron and Guerra (1938) used Lodder's medium and technique for their study of filamentous yeasts belonging to the genus Candida. Because they found that urea diffused through the medium so rapidly that it sometimes overlapped the diffusion zones of other nitrogen sources, only one other test substance was placed in the same plate. Langeron and Guerra found that 2 of their 16 species of Candida, C. pelliculosa and C. zeylanoides, utilized peptone only, but 6 assimilated urea. At variance with these results were the findings of Diddens and Lodder (1942) with respect to the assimilation reactions of the Candida species. They found that C. pelliculosa and C. zeylanoides utilized ammonium sulfate, urea, and asparagine in addition to peptone, and that the species C. tropicalis, C. guil-