Toxicidade de cádmio e zinco em Danio rerio: comparação entre valores permitidos em legislação para proteção da vida aquática e a potencial atuação como interferentes endócrinos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Propriedades estruturais e espectroscópicas de WO3 e WO3:Eu3+

Used as catalysts even in organic and inorganic molecules, as additives on catalysts, electrochromic films on smart windows the tungsten trioxide have been largely studied on the lasts decades, but there is just a few about it's luminescence. Using as precursors nitric acid and sodium tungstate the tungsten trioxide were been prepared thru wet process then treating on thermic and hydrothermal treatments. Where been evaluated the effects of methodology, nitric acid concentration, duration and temperature of treatments. The samples were characterized by X-ray diffraction (XRD), Raman scattering spectroscopy (RSS), Fourier transformed infrared spectroscopy, photoluminescence spectroscopy (PLS) and X-ray excited optical luminescence (XEOL). Hydrated phases of tungsten trioxide were obtained through hydrothermal treatments and the non-hydrated phases occur with thermic treatments. The acid concentration has the ability to determine the major phase formed as well the temperature determine the hydratation of the product. With lower temperatures dihydrate phase were preferable formed and with the rise of temperature, the water molecules were lost up to the fractionary hydratation and then the non-hydrated phase with higher temperatures depending on the atmosphere used on the thermal treatment. Doping the system with europium ions even substituting tungsten or in the interstices of the matrix were not been successful, as well the XEOL spectroscopy intensity were null and quite low for ultraviolet and visible excitation photoluminescence because of oxygen defect levels localized into the prohibited band.

RB30-246 Testing Ice Cream for Butterfat

Butterfat is usually the most expensive ingredient of ice cream; hence, great care is necessary in controllng its use. The manufacturer of ice cream, whether doing a large or a small volume of business, must manufacture a product that will comply with the established fat standard. Some means of determining the percentage of butterfat in the product must be available in order to establish this control. This 1930 research bulletin discusses the different testing equipment used to test butterfat in ice cream.

Propriedades estruturais e espectroscópicas de WO3 e WO3:Eu3+

Used as catalysts even in organic and inorganic molecules, as additives on catalysts, electrochromic films on smart windows the tungsten trioxide have been largely studied on the lasts decades, but there is just a few about it's luminescence. Using as precursors nitric acid and sodium tungstate the tungsten trioxide were been prepared thru wet process then treating on thermic and hydrothermal treatments. Where been evaluated the effects of methodology, nitric acid concentration, duration and temperature of treatments. The samples were characterized by X-ray diffraction (XRD), Raman scattering spectroscopy (RSS), Fourier transformed infrared spectroscopy, photoluminescence spectroscopy (PLS) and X-ray excited optical luminescence (XEOL). Hydrated phases of tungsten trioxide were obtained through hydrothermal treatments and the non-hydrated phases occur with thermic treatments. The acid concentration has the ability to determine the major phase formed as well the temperature determine the hydratation of the product. With lower temperatures dihydrate phase were preferable formed and with the rise of temperature, the water molecules were lost up to the fractionary hydratation and then the non-hydrated phase with higher temperatures depending on the atmosphere used on the thermal treatment. Doping the system with europium ions even substituting tungsten or in the interstices of the matrix were not been successful, as well the XEOL spectroscopy intensity were null and quite low for ultraviolet and visible excitation photoluminescence because of oxygen defect levels localized into the prohibited band.

Determination of trace elements in bovine semen samples by inductively coupled plasma mass spectrometry and data mining techniques for identification of bovine class

The reproductive performance of cattle may be influenced by several factors, but mineral imbalances are crucial in terms of direct effects on reproduction. Several studies have shown that elements such as calcium, copper, iron, magnesium, selenium, and zinc are essential for reproduction and can prevent oxidative stress. However, toxic elements such as lead, nickel, and arsenic can have adverse effects on reproduction. In this paper, we applied a simple and fast method of multi-element analysis to bovine semen samples from Zebu and European classes used in reproduction programs and artificial insemination. Samples were analyzed by inductively coupled plasma spectrometry (ICP-MS) using aqueous medium calibration and the samples were diluted in a proportion of 1:50 in a solution containing 0.01% (vol/vol) Triton X-100 and 0.5% (vol/vol) nitric acid. Rhodium, iridium, and yttrium were used as the internal standards for ICP-MS analysis. To develop a reliable method of tracing the class of bovine semen, we used data mining techniques that make it possible to classify unknown samples after checking the differentiation of known-class samples. Based on the determination of 15 elements in 41 samples of bovine semen, 3 machine-learning tools for classification were applied to determine cattle class. Our results demonstrate the potential of support vector machine (SVM), multilayer perceptron (MLP), and random forest (RF) chemometric tools to identify cattle class. Moreover, the selection tools made it possible to reduce the number of chemical elements needed from 15 to just 8.

Evaluation of Inductively Coupled Plasma Mass Spectrometry for Determining Ca, Cu, Fe, Mg, Mn, Se and Zn in Bovine Semen Samples using a Simple Sample Dilution Method

A simple and fast method for the determination of Ca, Cu, Fe, Mg, Mn, Se and Zn in bovine semen by quadrupole inductively coupled plasma spectrometry (q-ICP-MS) is described. Prior to analysis, samples (200 mu L) were diluted 1:50 in a solution containing 0.01% v/v Triton (R) X-100 and 0.5% v/v nitric acid and directly analyzed by ICP-MS. The limits of detection of the method are 0.3, 0.03, 0.2, 0.04, 0.04, 0.03 and 0.03 mu g L-1 for Ca-44, Cu-63, Fe-57, Mg-24, Zn-64, Se-82 and Mn-55, respectively. For purposes of comparison and method validation, four ordinary bovine semen samples were directly analyzed by ICP-MS and by flame atomic absorption spectrometry (FAAS) or graphite furnace atomic absorption spectrometry (GF AAS), with no statistical difference between the techniques at the 95% level when applying the t-test. Then, the proposed method was applied in the determinations of Ca, Cu, Fe, Mg, Mn, Se and Zn in collected samples of bovine semen from different breeds, which are used in reproduction programs and artificial insemination.

Avaliação de ICP OES com configuração axial ou radial para determinação de iodo em sal de cozinha

The performance of inductively-coupled plasma optical emission spectrometers with axial and radial views for determination of iodine in table salt was evaluated. Interference and memory effects in nitric acid and water-soluble tertiary amines (CFA-C) media were studied. Based on a factorial experiment, one optimum instrument operational condition for axial configuration, and two optima conditions for radial configuration was established. The ICP OES with axial view was 5-fold more sensitive than the radial view. Both matrix matching and standard addition methods were used for iodine quantification and for most samples, both strategies of calibration led to similar results. Recoveries ranged from 104 to 114%.

Evaluation of inductively coupled plasma mass spectrometry for determining Ca, Cu, Fe, Mg, Mn, Se and Zn in bovine semen samples using a simple sample dilution method

A simple and fast method for the determination of Ca, Cu, Fe, Mg, Mn, Se and Zn in bovine semen by quadrupole inductively coupled plasma spectrometry (q-ICP-MS) is described. Prior to analysis, samples (200 µL) were diluted 1:50 in a solution containing 0.01% v/v Triton® X-100 and 0.5% v/v nitric acid and directly analyzed by ICP-MS. The limits of detection of the method are 0.3, 0.03, 0.2, 0.04, 0.04, 0.03 and 0.03 µg L-1 for 44Ca, 63Cu, 57Fe, 24Mg, 64Zn, 82Se and 55Mn, respectively. For purposes of comparison and method validation, four ordinary bovine semen samples were directly analyzed by ICP-MS and by flame atomic absorption spectrometry (FAAS) or graphite furnace atomic absorption spectrometry (GF AAS), with no statistical difference between the techniques at the 95% level when applying the t-test. Then, the proposed method was applied in the determinations of Ca, Cu, Fe, Mg, Mn, Se and Zn in collected samples of bovine semen from different breeds, which are used in reproduction programs and artificial insemination.

Development of the optimal estimation method for inversion of stratospheric emission spectra and validation of HNO3 profiles

This doctoral thesis focuses on ground-based measurements of stratospheric nitric acid (HNO3)concentrations obtained by means of the Ground-Based Millimeter-wave Spectrometer (GBMS). Pressure broadened HNO3 emission spectra are analyzed using a new inversion algorithm developed as part of this thesis work and the retrieved vertical profiles are extensively compared to satellite-based data. This comparison effort I carried out has a key role in establishing a long-term (1991-2010), global data record of stratospheric HNO3, with an expected impact on studies concerning ozone decline and recovery. The first part of this work is focused on the development of an ad hoc version of the Optimal Estimation Method (Rodgers, 2000) in order to retrieve HNO3 spectra observed by means of GBMS. I also performed a comparison between HNO3 vertical profiles retrieved with the OEM and those obtained with the old iterative Matrix Inversion method. Results show no significant differences in retrieved profiles and error estimates, with the OEM providing however additional information needed to better characterize the retrievals. A final section of this first part of the work is dedicated to a brief review on the application of the OEM to other trace gases observed by GBMS, namely O3 and N2O. The second part of this study deals with the validation of HNO3 profiles obtained with the new inversion method. The first step has been the validation of GBMS measurements of tropospheric opacity, which is a necessary tool in the calibration of any GBMS spectra. This was achieved by means of comparisons among correlative measurements of water vapor column content (or Precipitable Water Vapor, PWV) since, in the spectral region observed by GBMS, the tropospheric opacity is almost entirely due to water vapor absorption. In particular, I compared GBMS PWV measurements collected during the primary field campaign of the ECOWAR project (Bhawar et al., 2008) with simultaneous PWV observations obtained with Vaisala RS92k radiosondes, a Raman lidar, and an IR Fourier transform spectrometer. I found that GBMS PWV measurements are in good agreement with the other three data sets exhibiting a mean difference between observations of ~9%. After this initial validation, GBMS HNO3 retrievals have been compared to two sets of satellite data produced by the two NASA/JPL Microwave Limb Sounder (MLS) experiments (aboard the Upper Atmosphere Research Satellite (UARS) from 1991 to 1999, and on the Earth Observing System (EOS) Aura mission from 2004 to date). This part of my thesis is inserted in GOZCARDS (Global Ozone Chemistry and Related Trace gas Data Records for the Stratosphere), a multi-year project, aimed at developing a long-term data record of stratospheric constituents relevant to the issues of ozone decline and expected recovery. This data record will be based mainly on satellite-derived measurements but ground-based observations will be pivotal for assessing offsets between satellite data sets. Since the GBMS has been operated for more than 15 years, its nitric acid data record offers a unique opportunity for cross-calibrating HNO3 measurements from the two MLS experiments. I compare GBMS HNO3 measurements obtained from the Italian Alpine station of Testa Grigia (45.9° N, 7.7° E, elev. 3500 m), during the period February 2004 - March 2007, and from Thule Air Base, Greenland (76.5°N 68.8°W), during polar winter 2008/09, and Aura MLS observations. A similar intercomparison is made between UARS MLS HNO3 measurements with those carried out from the GBMS at South Pole, Antarctica (90°S), during the most part of 1993 and 1995. I assess systematic differences between GBMS and both UARS and Aura HNO3 data sets at seven potential temperature levels. Results show that, except for measurements carried out at Thule, ground based and satellite data sets are consistent within the errors, at all potential temperature levels.

Studio di nuovi processi catalitici per la produzione di Acido Adipico

Adipic Acid (AA) is one of the most important chemicals in the actual worldwide Industrial Chemistry, because of his environmental and economical issues a lot of research challenge are open in this context. The main issue is regarding the substitution of Nitric Acid as oxidant in the last step of the industrial synthesis. This step, in fact, cause the production of various kind of nitrogen oxides that are gaseous pollutant and must be removed from the emissions. The substitution of Nitric Acid with molecular Oxygen or air as oxidant can avoid the production of nitric oxides reducing, in this way, the environmental and economic sustainability of the process. In this work is presented an alternative pathway for the synthesis of the AA. This concern a first step of oxidation with hydrogen peroxide that involve the transformation of ciclohexene into trans-1,2-cyclohexanediole than, the latter, is transformed into AA through a catalyzed oxidative cleavage with molecular Oxygen as oxidant. The first step has been already optimized by a work did in the past. This thesis is focused on the second step, here is presented an experimental work based on the study of the catalytic activity of three kind of catalyst, a Keggin heteropoliacid Mo-V, a Ru - based catalyst and an Au NP - based catalyst.

Simulations of physics and chemistry of polar stratospheric clouds with a general circulation model

A polar stratospheric cloud submodel has been developed and incorporated in a general circulation model including atmospheric chemistry (ECHAM5/MESSy). The formation and sedimentation of polar stratospheric cloud (PSC) particles can thus be simulated as well as heterogeneous chemical reactions that take place on the PSC particles. For solid PSC particle sedimentation, the need for a tailor-made algorithm has been elucidated. A sedimentation scheme based on first order approximations of vertical mixing ratio profiles has been developed. It produces relatively little numerical diffusion and can deal well with divergent or convergent sedimentation velocity fields. For the determination of solid PSC particle sizes, an efficient algorithm has been adapted. It assumes a monodisperse radii distribution and thermodynamic equilibrium between the gas phase and the solid particle phase. This scheme, though relatively simple, is shown to produce particle number densities and radii within the observed range. The combined effects of the representations of sedimentation and solid PSC particles on vertical H2O and HNO3 redistribution are investigated in a series of tests. The formation of solid PSC particles, especially of those consisting of nitric acid trihydrate, has been discussed extensively in recent years. Three particle formation schemes in accordance with the most widely used approaches have been identified and implemented. For the evaluation of PSC occurrence a new data set with unprecedented spatial and temporal coverage was available. A quantitative method for the comparison of simulation results and observations is developed and applied. It reveals that the relative PSC sighting frequency can be reproduced well with the PSC submodel whereas the detailed modelling of PSC events is beyond the scope of coarse global scale models. In addition to the development and evaluation of new PSC submodel components, parts of existing simulation programs have been improved, e.g. a method for the assimilation of meteorological analysis data in the general circulation model, the liquid PSC particle composition scheme, and the calculation of heterogeneous reaction rate coefficients. The interplay of these model components is demonstrated in a simulation of stratospheric chemistry with the coupled general circulation model. Tests against recent satellite data show that the model successfully reproduces the Antarctic ozone hole.

Aufbau eines flugzeuggetragenen Massenspektrometers zur Messung von HNO 3 und HONO und Quantifizierung der HNO 3-Aufnahme in Eispartikel in Kondensstreifen und Zirren

Im Zuge dieser Arbeit ist ein Massenspektrometer zur flugzeuggetragenen Messung von HNO3 und HONO auf dem neuen deutschen Forschungsflugzeug HALO aufgebaut worden (AIMS - Atmospheric chemical Ionization Mass Spectrometer). Die Ionisation der HNO3- und HONO-Moleküle erfolgt chemisch durch Reaktion mit SF5- -Ionen. Basierend auf den Ergebnissen von Laborversuchen wurden die Betriebsparameter optimiert, die Einzelkomponenten im HALO-Rack zusammengestellt und eine Einlassleitung entworfen, die Wandeffekte minimiert und Untergrundmessungen und HNO3-Kalibrationen im Flug ermöglicht. Die Empfindlichkeit der Messung von HNO3 und HONO wurde ebenso im Labor untersucht wie Interferenzen mit Wasserdampf und Ozon. Die HONO-Vergleichskampagne FIONA am Europäischen Photoreaktor (EUPHORE) in Valencia war die erste Messkampagne mit AIMS. Bei den offenen Vergleichsmessungen stimmten die von AIMS gemessenen HONO-Mischungsverhältnisse innerhalb +-20% mit dem Median von 9 weiteren HONO-Messungen überein. Die ersten flugzeuggetragenen Messungen mit AIMS werden im Verlauf der HALO-Missionen ML-CIRRUS und TACTS stattfinden. Neben dem Aufbau und der Charakterisierung von AIMS war die Analyse der Aufnahme von HNO3 in Eispartikel von Kondensstreifen und Zirren Gegenstand dieser Arbeit. Die Aufnahme von HNO3 in Kondensstreifeneispartikel wurde erstmals systematisch anhand einer Flugzeugmesskampagne (CIRRUS-III) untersucht. Während CIRRUS-III im November 2006 wurden Zirren und zufällig knapp 40 persistente Kondensstreifen über Deutschland und Nordeuropa beprobt. Die Messungen fanden in Höhen zwischen 10 und 11.5 km und bei Temperaturen zwischen 210 und 230 K statt. Die HNO3-Konzentration wurde mit Hilfe von NOy-Messungen bestimmt. Im Mittel war in Kondensstreifen ein größerer Anteil des Gesamt-HNO3 in den Eispartikeln gebunden (6 %) als in Zirren (3 %). Das Gasphasenäquivalent des eisgebundenen HNO3 betrug in Zirren durchschnittlich 6 pmol/mol, in Kondensstreifen 14 pmol/mol und in jungen Kondensstreifen (Alter<1 h) 21 pmol/mol. Das Mischungsverhältnis von HNO3 zu H2O in Eispartikeln war in Kondensstreifen leicht höher als in Zirren unter ähnlichen meteorologischen Bedingungen. Ursächlich für die höheren Werte in persistenten Kondensstreifen sind wahrscheinlich die hohen HNO3-Konzentrationen in den Abgasfahnen der Flugzeuge bei der Kondensstreifenbildung. Die beobachtete Abnahme des HNO3/H2O-Molverhältnisses mit zunehmendem Effektivdurchmesser der Eispartikel deutet an, dass die HNO3-Konzentrationen in Eispartikeln von jungen Kondensstreifen durch die Aufnahme von Abgas-HNO3 in die gefrierenden Aerosolpartikel bestimmt wird. Die Konzentrationen in älteren Kondensstreifen werden zunehmend durch das Vergraben von Umgebungs-HNO3 in wachsenden Eispartikeln kontrolliert. Diese Studie leistet einen Beitrag zu einem besseren Prozessverständnis der HNO3-Aufnahme in atmosphärische Eispartikel. Sie motiviert die Nutzung persistenter Kondensstreifen als atmosphärisches Labor zur Untersuchung der Spurengasaufnahme in wachsende Eispartikel.

Exchange of nitrogen dioxide (NO 2) between plants and the atmosphere under laboratory and field conditions

Nitrogen is an essential nutrient. It is for human, animal and plants a constituent element of proteins and nucleic acids. Although the majority of the Earth’s atmosphere consists of elemental nitrogen (N2, 78 %) only a few microorganisms can use it directly. To be useful for higher plants and animals elemental nitrogen must be converted to a reactive oxidized form. This conversion happens within the nitrogen cycle by free-living microorganisms, symbiotic living Rhizobium bacteria or by lightning. Humans are able to synthesize reactive nitrogen through the Haber-Bosch process since the beginning of the 20th century. As a result food security of the world population could be improved noticeably. On the other side the increased nitrogen input results in acidification and eutrophication of ecosystems and in loss of biodiversity. Negative health effects arose for humans such as fine particulate matter and summer smog. Furthermore, reactive nitrogen plays a decisive role at atmospheric chemistry and global cycles of pollutants and nutritive substances.rnNitrogen monoxide (NO) and nitrogen dioxide (NO2) belong to the reactive trace gases and are grouped under the generic term NOx. They are important components of atmospheric oxidative processes and influence the lifetime of various less reactive greenhouse gases. NO and NO2 are generated amongst others at combustion process by oxidation of atmospheric nitrogen as well as by biological processes within soil. In atmosphere NO is converted very quickly into NO2. NO2 is than oxidized to nitrate (NO3-) and to nitric acid (HNO3), which bounds to aerosol particles. The bounded nitrate is finally washed out from atmosphere by dry and wet deposition. Catalytic reactions of NOx are an important part of atmospheric chemistry forming or decomposing tropospheric ozone (O3). In atmosphere NO, NO2 and O3 are in photosta¬tionary equilibrium, therefore it is referred as NO-NO2-O3 triad. At regions with elevated NO concentrations reactions with air pollutions can form NO2, altering equilibrium of ozone formation.rnThe essential nutrient nitrogen is taken up by plants mainly by dissolved NO3- entering the roots. Atmospheric nitrogen is oxidized to NO3- within soil via bacteria by nitrogen fixation or ammonium formation and nitrification. Additionally atmospheric NO2 uptake occurs directly by stomata. Inside the apoplast NO2 is disproportionated to nitrate and nitrite (NO2-), which can enter the plant metabolic processes. The enzymes nitrate and nitrite reductase convert nitrate and nitrite to ammonium (NH4+). NO2 gas exchange is controlled by pressure gradients inside the leaves, the stomatal aperture and leaf resistances. Plant stomatal regulation is affected by climate factors like light intensity, temperature and water vapor pressure deficit. rnThis thesis wants to contribute to the comprehension of the effects of vegetation in the atmospheric NO2 cycle and to discuss the NO2 compensation point concentration (mcomp,NO2). Therefore, NO2 exchange between the atmosphere and spruce (Picea abies) on leaf level was detected by a dynamic plant chamber system under labo¬ratory and field conditions. Measurements took place during the EGER project (June-July 2008). Additionally NO2 data collected during the ECHO project (July 2003) on oak (Quercus robur) were analyzed. The used measuring system allowed simultaneously determina¬tion of NO, NO2, O3, CO2 and H2O exchange rates. Calculations of NO, NO2 and O3 fluxes based on generally small differences (∆mi) measured between inlet and outlet of the chamber. Consequently a high accuracy and specificity of the analyzer is necessary. To achieve these requirements a highly specific NO/NO2 analyzer was used and the whole measurement system was optimized to an enduring measurement precision.rnData analysis resulted in a significant mcomp,NO2 only if statistical significance of ∆mi was detected. Consequently, significance of ∆mi was used as a data quality criterion. Photo-chemical reactions of the NO-NO2-O3 triad in the dynamic plant chamber’s volume must be considered for the determination of NO, NO2, O3 exchange rates, other¬wise deposition velocity (vdep,NO2) and mcomp,NO2 will be overestimated. No significant mcomp,NO2 for spruce could be determined under laboratory conditions, but under field conditions mcomp,NO2 could be identified between 0.17 and 0.65 ppb and vdep,NO2 between 0.07 and 0.42 mm s-1. Analyzing field data of oak, no NO2 compensation point concentration could be determined, vdep,NO2 ranged between 0.6 and 2.71 mm s-1. There is increasing indication that forests are mainly a sink for NO2 and potential NO2 emissions are low. Only when assuming high NO soil emissions, more NO2 can be formed by reaction with O3 than plants are able to take up. Under these circumstance forests can be a source for NO2.

Charakterisierung von optischen Partikelspektrometern und in-situ Messungen zur Mikrophysik der polaren Stratosphärenwolken

Polare Stratosphärenwolken (PSC), die unterhalb einer Temperatur von etwa -78 °C in polaren Regionen auftreten, üben einen starken Einfluss auf die stratosphärische Ozonschicht aus. Dieser Einfluss erfolgt größtenteils über heterogene chemische Reaktionen, die auf den Oberflächen von Wolkenpartikeln stattfinden. Chemische Reaktionen die dabei ablaufen sind eine Voraussetzung für den späteren Ozonabbau. Des Weiteren verändert die Sedimentation der Wolkenpartikel die chemische Zusammensetzung bzw. die vertikale Verteilung der Spurengase in der Stratosphäre. Für die Ozonchemie spielt dabei die Beseitigung von reaktivem Stickstoff durch Sedimentation Salpetersäure-haltiger Wolkenpartikeln (Denitrifizierung) eine wichtige Rolle. Durch gleichen Sedimentationsprozess von PSC Elementen wird der Stratosphäre des weiteren Wasserdampf entzogen (Dehydrierung). Beide Prozesse begünstigen einen länger andauernden stratosphärischen Ozonabbau im polaren Frühling.rnGerade im Hinblick auf die Denitrifikation durch Sedimentation größerer PSC-Partikel werden in dieser Arbeit neue Resultate von in-situ Messungen vorgestellt, die im Rahmen der RECONCILE-Kampagne im Winter des Jahres 2010 an Bord des Höhenforschungs-Flugzeugs M-55 Geophysica durchgeführt wurden. Dabei wurden in fünf Flügen Partikelgrößenverteilungen in einem Größenbereich zwischen 0,5 und 35 µm mittels auf der Lichtstreuung basierender Wolkenpartikel-Spektrometer gemessen. Da polare Stratosphärenwolken in Höhen zwischen 17 und 30 km auftreten, sind in-situ Messungen vergleichsweise selten, so dass noch einige offene Fragen bestehen bleiben. Gerade Partikel mit optischen Durchmessern von bis zu 35µm, die während der neuen Messungen detektiert wurden, müssen mit theoretischen Einschränkungen in Einklang gebracht werden. Die Größe der Partikel wird dabei durch die Verfügbarkeit der beteiligten Spurenstoffe (Wasserdampf und Salpetersäure), die Sedimentationsgeschwindigkeit, Zeit zum Anwachsen und von der Umgebungstemperatur begrenzt. Diese Faktoren werden in der vorliegenden Arbeit diskutiert. Aus dem gemessenen Partikelvolumen wird beispielsweise unter der Annahme der NAT-Zusammensetzung (Nitric Acid Trihydrate) die äquivalente Konzentration des HNO 3 der Gasphase berechnet. Im Ergebnis wird die verfügbare Konzentration von Salpetersäure der Stratosphäre überschritten. Anschließend werden Hypothesen diskutiert, wodurch das gemessene Partikelvolumen überschätzt worden sein könnte, was z.B. im Fall einer starken Asphärizität der Partikel möglich wäre. Weiterhin wurde eine Partikelmode unterhalb von 2-3µm im Durchmesser aufgrund des Temperaturverhaltens als STS (Supercooled Ternary Solution droplets) identifiziert.rnUm die Konzentration der Wolkenpartikel anhand der Messung möglichst genau berechnen zu können, muss das Messvolumen bzw. die effektive Messfläche der Instrumente bekannt sein. Zum Vermessen dieser Messfläche wurde ein Tröpfchengenerator aufgebaut und zum Kalibrieren von drei Instrumenten benutzt. Die Kalibration mittels des Tröpfchengenerators konzentrierte sich auf die Cloud Combination Probe (CCP). Neben der Messfläche und der Größenbestimmung der Partikel werden in der Arbeit unter Zuhilfenahme von Messungen in troposphärischen Wolken und an einer Wolkensimulationskammer auch weitere Fehlerquellen der Messung untersucht. Dazu wurde unter anderem die statistische Betrachtung von Intervallzeiten einzelner Messereignisse, die in neueren Sonden aufgezeichnet werden, herangezogen. Letzteres ermöglicht es, Messartefakte wie Rauschen, Koinzidenzfehler oder „Shattering“ zu identifizieren.rn

Windkanalstudien zum Graupelwachstum und Bestimmung von Retentionskoeffizienten verschiedener Spurengase während der Bereifung

Am vertikalen Windkanal der Johannes Gutenberg-Universität Mainz wurden physikalische und chemische Bereifungsexperimente durchgeführt. Dabei lagen die Umgebungstemperaturen bei allen Experimenten zwischen etwa -15 und -5°C und der Flüssigwassergehalt erstreckte sich von 0,9 bis etwa 1,6g/m³, typische Bedingungen für Mischphasenwolken in denen Bereifung stattfindet. Oberflächentemperaturmessungen an wachsenden hängenden Graupelpartikeln zeigten, dass während der Experimente trockene Wachstumsbedingungen herrschten.rnZunächst wurde das Graupelwachstum an in einer laminaren Strömung frei schwebenden Eispartikeln mit Anfangsradien zwischen 290 und 380µm, die mit flüssigen unterkühlten Wolkentröpfchen bereift wurden, studiert. Ziel war es, den Kollektionskern aus der Massenzunahme des bereiften Eispartikels und dem mittleren Flüssigwassergehalt während des Wachstumsexperimentes zu bestimmen. Die ermittelten Werte für die Kollektionskerne der bereiften Eispartikel erstreckten sich von 0,9 bis 2,3cm³/s in Abhängigkeit ihres Kollektorimpulses (Masse * Fallgeschwindigkeit des bereifenden Graupels), der zwischen 0,04 und 0,10gcm/s lag. Bei den Experimenten zeigte sich, dass die hier gemessenen Kollektionskerne höher waren im Vergleich mit Kollektionskernen flüssiger Tropfen untereinander. Aus den aktuellen Ergebnissen dieser Arbeit und der vorhandenen Literaturwerte wurde ein empirischer Faktor entwickelt, der von dem Wolkentröpfchenradius abhängig ist und diesen Unterschied beschreibt. Für die untersuchten Größenbereiche von Kollektorpartikel und flüssigen Tröpfchen können die korrigierten Kollektionskernwerte in Wolkenmodelle für die entsprechenden Größen eingebunden werden.rnBei den chemischen Experimenten zu dieser Arbeit wurde die Spurenstoffaufnahme verschiedener atmosphärischer Spurengase (HNO3, HCl, H2O2, NH3 und SO2) während der Bereifung untersucht. Diese Experimente mussten aus technischen Gründen mit hängenden Eispartikeln, dendritischen Eiskristallen und Schneeflocken, bereift mit flüssigen Wolkenlösungströpfchen, durchgeführt werden.rnDie Konzentrationen der Lösung, aus der die Wolkentröpfchen mit Hilfe von Zweistoffdüsen erzeugt wurden, lagen zwischen 1 und 120mg/l. Für die Experimente mit Ammoniak und Schwefeldioxid wurden Konzentrationen zwischen 1 und 22mg/l verwendet. Das Schmelzwasser der bereiften hängenden Graupel und Schneeflocken wurden ionenchromatographisch analysiert und zusammen mit der bekannten Konzentration der bereifenden Wolkentröpfchen konnte der Retentionskoeffizient für jeden Spurenstoff bestimmt werden. Er gibt die Menge an Spurenstoff an, die bei der Phasenumwandlung von flüssig zu fest in die Eisphase übergeht. Salpetersäure und Salzsäure waren nahezu vollständig retiniert (Mittelwerte der gesamten Experimente entsprechend 99±8% und 100±9%). Für Wasserstoffperoxid wurde ein mittlerer Retentionskoeffizient von 65±17% bestimmt. rnDer mittlere Retentionskoeffizient von Ammoniak ergab sich unabhängig vom Flüssigwassergehalt zu 92±21%, während sich für Schwefeldioxid 53±10% für niedrige und 29±7% für hohe Flüssigphasenkonzentrationen ergaben. Bei einigen der untersuchten Spurenstoffe wurde eine Temperaturabhängigkeit beobachtet und wenn möglich durch Parametrisierungen beschrieben.rn