Concentrations Of Minor Constituents Research Articles

A 1-D model to retrieve the vertical profiles of minor atmospheric constituents for cloud microphysical modeling: I. Formulation and validation

Determining the number concentration of minor constituents in the atmosphere is very important as it determines the whole tropospheric chemistry process. These constituents may act as cloud condensation nuclei (CCN) and ice nuclei (IN), impacting heterogeneous nucleation inside the cloud. However, the estimations of the number concentration of CCN/IN in cloud microphysical parameters are associated with uncertainties. In the present work, a hybrid Monte Carlo Gear solver has been developed to retrieve profiles of CH4, N2O, and SO2. The idealized experiments have been carried out using this solver for retrieving vertical profiles of these constituents over four megacities, viz., Delhi, Mumbai, Chennai, and Kolkata. Community Long-term Infrared Microwave Coupled Atmospheric Product System (CLIMCAPS) dataset around 0800 UTC (2000UTC) has been used for initializing the number concentration of CH4, N2O, and SO2 for daytime (nighttime). The daytime (nighttime) retrieved profiles have been validated using 2000 UTC (next day 0800 UTC) CLIMCAPS products. ERA5 temperature dataset has been used to estimate the kinematic rate of reactions with 1000 perturbations determined using Maximum Likelihood Estimation (MLE). The retrieved profiles and CLIMCAPS products are in very good agreement, as evidenced by the percentage difference between them within the range of 1.3 × 10−5–60.8 % and the coefficient of determination mainly within the range between 81 and 97 %. However, during the passage of tropical cyclone and western disturbance, its value became as low as 27 and 65 % over Chennai and Kolkata, respectively. The enactment of synoptic scale systems such as western disturbances, tropical cyclone Amphan, and easterly waves caused disturbed weather over these megacities—the retrieved profiles during disturbed weather cause large deviations of vertical profiles of N2O. However, the profiles of CH4 and SO2 have less deviation. It is inferred that incorporating this methodology in the dynamical model will be useful to simulate the realistic vertical profiles of the minor constituents in the atmosphere.

Effects of Monoacylglycerols on the Cold Flow Properties of Biodiesel

AbstractBiodiesel is a renewable alternative fuel made from plant oils and animal fats that may be burned in a compression–ignition (diesel) engine. It is composed of mono‐alkyl fatty acid esters made from plant oils or animal fats mainly by transesterification with methanol or ethanol. This process leaves behind small concentrations of minor constituents including monoacylglycerols (MAG). Saturated MAG have low solubility in biodiesel and may form solid residues during storage in cold weather. Soybean oil‐fatty acid methyl esters (SME) were mixed with up to 1.0 mass% MAG to evaluate the effects on cloud point (CP), freezing point (FP), cold filter plugging point (CFPP), and wax appearance point (WAP). Differential scanning calorimetry (DSC) results showed that MAG with only 27.6 mass% total long chain (C16–C18) saturated fatty acid content had melting transitions between 54 and 59.0 °C. Furthermore, DSC analysis indicated that pure monoolein may be problematic with respect to melting transitions between 25.4 and 33.4 °C. Solubility data for SME–MAG mixtures indicated a broad transition temperature range from solid at low temperature to liquid at temperatures exceeding 60 °C. Increasing the added MAG content from 0.10 to 1.0 mass% increased both CP and FP. Cold filter plugging point demonstrated higher sensitivity than CP or FP at added MAG content below 0.10 mass%, though it was not affected by increasing MAG concentration above 0.50 mass%. Wax appearance point showed no effects until added MAG content exceeded 0.25 mass%. Kinematic viscosity measured at 5 °C similarly showed no effects until added MAG concentration exceeded 0.20 mass%. Specific gravity at 15.6 °C and refractive index at 25 °C were not greatly affected by added MAG except at concentrations greater than 0.10 mass%.

Laser-induced breakdown spectroscopy of molten aluminum alloy.

We have demonstrated that a fiber-optic laser-induced breakdown spectroscopy (LIBS) probe is suitable for measuring the concentration of minor constituents of a molten Al alloy in a laboratory furnace. For the first time to our knowledge we are able to record the LIBS spectra in several spectral regions of seven different molten Al alloy samples by inserting the LIBS probe inside the molten alloys, allowing us to obtain a ratio calibration curve for minor constituents (Cr, Mg, Zn, Cu, Si, etc.), using Fe as a reference element. A ratio calibration curve for Fe with a major element (Al) can also be obtained with which the concentration of Fe in the alloy can be determined. The effects of the surrounding atmosphere on the LIBS spectra of the molten alloy were investigated. Effects of focal length of the lens on the LIBS signals were also studied. LIBS spectra of a solid Al alloy recorded with the same LIBS probe were compared with the LIBS spectra of the molten alloy. Our results suggest that the LIBS probe is useful for monitoring the elemental composition of an Al melt in an industrial furnace at different depths and different positions inside the melt.

The feasibility of monitoring CO2 from high‐resolution infrared sounders

Satellite instruments specifically designed to monitor atmospheric carbon dioxide concentrations have not been flown to date but, high‐resolution infrared sounders, being launched in the next few years, may offer the possibility of at least a basic carbon dioxide monitoring capability. This paper explores the sensitivity of this new generation of advanced infrared sounders to changing carbon dioxide concentrations and also compares this with uncertainties due to the atmospheric temperature, water vapor, and minor constituent concentrations using the current background errors in numerical weather prediction models as a baseline. The sensitivity results shown are computed for the Infrared Atmospheric Sounding Interferometer (IASI), which is due to fly on the European METOP platform from 2005. We show that although the carbon dioxide signal is below or at the instrument noise for IASI and that uncertainties in temperature and water vapor errors can dominate, a careful averaging of the retrieved carbon dioxide fields over areas of 500 × 500 km2 and 2 weeks should be able to extract changes at the level of 1% or less in the total column carbon dioxide amount. We also show results of an information content study for the Atmospheric InfraRed Sounder, AIRS, data, which suggests 50 channels are adequate for inferring the tropospheric carbon dioxide amounts but that they are not sensitive to CO2 changes in the boundary layer.

Minor constituent concentrations measured from a high altitude aircraft using high resolution far-infrared Fourier transform spectroscopy.

Far-infrared emission spectroscopy has beendemonstrated to be a valuable method for remotesensing of trace species in the stratosphere, with theability to simultaneously detect a number of keychemical species. SAFIRE-A is a new far-infraredFourier Transform (FT) spectrometer which has beenspecifically designed to operate on board of a highaltitude aircraft in the lower stratosphere and uppertroposphere regions where relatively few remotesensing measurements have been made. Using newtechnology, the sensitivity of the FT spectrometermethod has been substantially improved for the longwavelength region. Results are reported formeasurements of O3, HNO3 and N2O at 17and 19 km using a detection window near 23 cm-1.Geographical and altitude variability of the volumemixing ratio of these constituents and their relativecorrelation are discussed. Ozone measurements agreewell with in situ measurements, except in regions ofstrong stirring and mixing associated with deformationof the northern vortex edge. Whilst SAFIREmeasurements of trace gases do not capture all of thelocal variability seen by rapid in-situ techniques,they can indicate horizontal variability close to, butnot intercepted by, the aircraft's flight path. Apossible detection of ClO at the low background levelsexpected outside the polar vortex is also reported.

On Krassovsky's ratio for ter-diurnal hydroxyl oscillations in the winter polar mesopause

Past observations of ter-diurnal oscillations in hydroxyl brightness and rotational temperature of the winter polar mesopause have revealed two apparently conflicting facets. The 8 h wave is a commonly observed feature, possibly the most recurring tide of that region. On the other hand, temperature changes were observed to lead changes in brightness, implying a negative phase of Krassovsky's ratio. (Krassovsky's ratio is the ratio of normalized airglow brightness variation to normalized temperature variation.) This qualitatively supports a gravity wave explanation according to predictions of current dynamical-chemical models of fluctuations in airglow emissions. But the ter-diurnal oscillations are not likely due to gravity waves because of the persistence of the oscillations. Here a statistically-significant sample (23 individual days) of clear ter-diurnal waves of the winter polar mesopause over Eureka, NWT (80°N), is considered in order to establish the range of observed amplitude and phase of Krassovsky's ratio and compare with the predicted values. The observed amplitude of Krassovsky's ratio was 2.6–8.1 with the majority of cases (74%) at 4±1. The phase of Krassovsky's ratio was negative for all 23 cases, i.e. changes in temperature led changes in brightness. In the majority of cases the negative phase was significantly different from zero. Theoretical calculations for two different model atmospheres (both isothermal and non-isothermal) were performed using a current model of tidally driven hydroxyl airglow fluctuations. The predicted phase of Krassovsky's ratio was slightly positive (≤ +30°) for an 8 h gravitational zonally symmetric tide of meridional index 2–5 and a migrating tide of meridional index 3–7. It is concluded that the theoretical predictions of Krassovsky's ratio of oscillations in hydroxyl emission induced by zonally symmetric tides and migrating tides as applied to the two model atmospheres do not agree with the above observations of the winter polar mesopause. Neither do the theoretical predictions of Krassovsky's ratio for gravity wave-driven fluctuations in OH nightglow from an extended, dissipative emission region match the observed value for the vast majority (87%) of days with clear ter-diurnal oscillations. The consistently negative phases over Eureka probably reflect unique conditions in the very high latitude winter mesopause region characterized by strong lapse rates in the emission layer or background minor constituent concentrations that differ significantly from model predictions.

Characterization of Gas Reburning-Sorbent Injection Technology By-Products

ABSTRACTThree samples of fly ashes from pilot-scale tests of gas reburning and sorbent injection (GR-SI) technology were characterized physically, chemically, and mineralogically. Texturally, the samples consist of approximately 97% by weight of silt-size particles. Total chemical analysis showed that Al, Ca, C, Fe, Si, and S were the major elements, making up 56% of the total mass of the sample on average. Approximately 3% of the sample mass consisted of the elements Cl, Mg, P, K, Na, and Ti, and 0.4% consisted of trace elements. Major crystalline compounds found in these samples were lime (CaO), anhydrite (CaSO4), and calcium carbonate (CaCO3). Calculations show that these compounds constituted from 56 to 76% of the mass of the samples. The morphology and chemistry of particles in GR-SI samples were similar to those of particles in conventional coal fly ashes. The particles in the GR-SI samples consisted of fragments and spheres of varying sizes. Most of the particles were calcareous. Silicate and alumino-silicate particles were fewer in number, and iron-rich particles were rare. The EP test indicated that extract concentrations of Ag, As, Ba, Cd, Cr, Pb, and Se were well below the EPA regulatory levels. Predictions of leachate compositions from these types of fly ashes, if disposed of as a landfill at a midwestern U.S. site indicate, that during the first ten years the concentrations of Ca, SO4, Na, B, and OH would remain high. The concentrations of minor constituents (As, Ba, Cd, Cd, Cu, Cr, Fe, Ni, and Se) in the leachate are predicted to be at trace levels.

Minor and trace elemental contents of cancerous breast tissue measured by instrumental and radiochemical neutron activation analysis

Many minor and trace elements influence the permeability of cell membranes by competing for binding sites, and exert direct or indirect action on the carcinogenic process. Instrumental and radiochemical neutron activation analysis has been employed for the determination of more than 20 elements in normal and cancerous breast tissues of 6 patients. Most trace elements, viz., Zn, Cu, Mn, Co, Se, Br, As, Sb and Cd, are elevated in cancerous tissue, whereas lower levels are observed for Fe, Cs, I, and Sr. Similarly, concentrations of minor constituents, such as Na, K, P, Cl, and Mg, are enhanced compared to normal tissue. Several elements incorporate into the normal cell, change its enzymatic activity, and accelerate the growth of tumor.

太平洋諸島産コーラルアラゴナイト中の少量成分含量

太平洋諸島産コーラルアラゴナイト中の少量成分含量

Middle atmosphere tides

Recent progress in the study of middle atmosphere tides is reviewed. Specific areas where recent progress has occurred include: development of more realistic thermal excitation and numerical simulation models; the role of tides in accelerating and heating the mean flow at the base of the thermosphere; observational efforts which delineate average seasonal, latitudinal and vertical structures of tides, and shorterterm variations of tides about these values; theoretical and observational studies concerning the importance of non-migrating tidal components; the effects of tides on minor constituent concentrations in the upper mesosphere and lower thermosphere. The review concludes with a summary of key problems to be addressed in the future.

Preliminary results and validation of a 2D model employing a residual circulation formalism

A two-dimensional, photochemical model of the atmosphere has been developed and valitated with existing experimental data. The reason to develop this model is to predict the concentrations of minor constituents of the atmosphere to be compared with data obtained in an articulate measurement compaign. The originality of our approach is to use a residual mean calculation and a set of eddy diffusion coefficients obtained from a general circulation model of the stratosphere. The advantage of this approach, based on more sound physical basis, is to reduce the importance of the eddy diffusion coefficients. Results are presented for NO x (NO+NO2), odd hydrogen, HNO3, HCl, ClO. They show that the quality of our predictions is comparable to existing parametrized two-dimensional model. We attribute the disagreements to the simplicity of the chemical scheme. Improvements on this scheme and on the treatment of the diurnal variations are planned for this model.

Detection of minor constitutents of the stratosphere by far infrared emission spectroscopy

The far infrared (30–110 cm−1) emission spectrum of the lower stratosphere has been measured from balloon altitudes with a high resolution (0.06 cm−1) rapid-scanning Michelson interferometer on two flights in 1976. The quality and resolution of the spectra obtained from two altitudes have permitted a careful search for emission lines from environmentally important molecules such as HCl, NO2, OH, H2O2, and CO, among the more prominent and well-known features due to H2O, O3 and O2. Column densities have been determined for H2O and O3 and upper limit estimates have been made from tentative identifications of several other constituents. However, the large angular field of view observed by the instrument prevented the determination of concentration profiles from atmospheric limb scans to the horizon. The possible future directions of this technique are outlined on the basis of operating experience over a 6 year programme. The viability of this method of monitoring the concentrations of minor constituents in the stratosphere is discussed with respect to other equivalent techniques.

The hydrogeochemistry of the Jurassic limestones in Gloucestershire, England

Summary This study is a review of the major and minor chemical constituents in groundwater in the Jurassic limestones of Gloucestershire, England. Particular emphasis has been placed on the identification of hydrogeochemical processes. Groundwaters in the limestones of the Great Oolite Series and the Inferior Oolite Series, where they are unconfined, are of the Ca, HCO 3 type. In areas where both limestone series are confined beneath clays there is a gradual change in the chemistry to a Na, HCO 3 type. Deep within the confined limestones, particularly in the Great Oolite series, an Na, Cl component has been identified. Natural heavy metal concentrations are generally very low except where old pipework has influenced the Pb or Zn content. Significant down-dip chemical changes in terms of redox conditions, pH, dissolved oxygen content, ion-exchange and the concentrations of minor constituents are exhibited by groundwaters in the limestones of both series. An oxidation-reduction zone has been defined in each limestone unit. In the Inferior Oolite the zone occurs some 8 km down-gradient from the onset of confined conditions. In the Great Oolite a similar zone occurs 1–2 km into the confined area. The delay in the onset of reducing conditions in the Inferior Oolite is tentatively attributed to leakage of Great Oolite water through the intervening Fullers Earth.

Variations in electron density in the middle latitude D-region above Urbana, Illinois

Electron density measurements made with the partial reflections technique above Urbana, Illinois (44°10′N, 88°10′W) were analysed for day-to-day variations, seasonal variations, magnetic storm after-effects and stratosphere-ionosphere coupling effects. As well as showing a winter anomaly, the electron densities near 76 kilometres were significantly lower in fall than in spring. Magnetic storm after-effects of the type predicted by models of energetic electron precipitation at middle latitudes were observed. No strong correlations were found between stratospheric and D-region time series, or between the occurrence of stratospheric warmings and D-region changes. It is likely that most of the electron density variation was due to variations in the transport of minor neutral constituents. The spring-fall differences were also probably caused by differences in minor constituent concentrations rather than the effect of temperature changes on the recombination coefficient.

Chemical response of the middle atmosphere to changes in the ultraviolet solar flux

Time variations in the solar flux between 1000 and 4000 Å induce changes in the concentrations of minor constituents in the upper stratosphere and mesosphere. The response of mesospheric ozone to variations in the Lyman α line over the course of several solar rotations may be of measurable magnitude. Large Lyman α fluxes lead to small O 3 densities above 65 km due to the enhanced dissociation of H 2O and resultant destruction of odd oxygen by odd hydrogen. An increase in continuum and Lyman α fluxes causes a slight enhancement in both the odd oxygen and hydrogen concentrations in the upper stratosphere.

Far infrared emission spectrum of the stratosphere from balloon altitudes

WE present here observations of the far infrared emission spectrum of the stratosphere taken with a balloon-borne interferometer from an altitude of 22 km above Churchill, Manitoba, Canada (latitude 58.7°N, longitude 94° W) in July, 1974. The instrument was part of a composite Atmospheric Environment Service of Canada gondola whose overall aim was the measurement, by several complementary methods, of the concentrations of minor constituents of the atmosphere and the monitoring of their changes with altitude and time during the flight. Many of the minor constituents of particular interest in the current debate on stratospheric pollution (O3, H2O, NO2, N2O, NO, HNO3, HCl, SO2) exhibit pure rotation spectra in the far infrared and are expected to contribute to the stratospheric emission spectrum. O2, a well known and well behaved constituent of the stratosphere emits a series of weak magnetic dipole lines in this wavelength region, with intensities matching those of intrinsically stronger ones from less abundant species, and which can be used for spectral normalisation (see ref. 3).

High temperature plasticity of lithium zinc silicate glass-ceramics

A plasticity model involving dilatancy and stress-induced dissolution of crystalline material has been formulated to qualitatively account for the high temperature constant strain-rate and steady state creep data obtained for a glass-ceramic derived from the SiO=Li20-ZnO system and reported previously. To test the model further, high temperature stress relaxation experiments have been carried out on the same material. Also, by altering the concentrations of minor constituents, including the nucleating agent, it has been possible to examine the effects on mechanical properties of both the grain size and the viscosity of the non-crystalline material.

The concentration and transport of minor constituents in the mesosphere and lower thermosphere (70–110 km) during periods of anomalous absorption

The concentration of minor constituents which are required to produce the winter ‘anomaly’ of midlatitude radio wave absorption are evaluated. Between 85 and 100 km increases above presently measured values are by a factor of 30–150 for nitric oxide or ~10 3 for metastable oxygen ( O 2( 1Δ g ). Nitric oxide transported from the auroral zone has been suggested as a possible source of minor constituent; such a process would require ratios there of n(NO) n( 2 ) > 0.1 near 115km. The January 1963 stratospheric warmings and associated ionospheric and thermospheric (90–100 km) changes are consistent with this hypothesis.