Application of comprehensive gas chromatography (GCxGC) to measurements of volatile organic species in ambient air

The focus of this thesis was the in-situ application of the new analytical technique "GCxGC" in both the marine and continental boundary layer, as well as in the free troposphere. Biogenic and anthropogenic VOCs were analysed and used to characterise local chemistry at the individual measurement sites. The first part of the thesis work was the characterisation of a new set of columns that was to be used later in the field. To simplify the identification, a time-of-flight mass spectrometer (TOF-MS) detector was coupled to the GCxGC. In the field the TOF-MS was substituted by a more robust and tractable flame ionisation detector (FID), which is more suitable for quantitative measurements. During the process, a variety of volatile organic compounds could be assigned to different environmental sources, e.g. plankton sources, eucalyptus forest or urban centers. In-situ measurements of biogenic and anthropogenic VOCs were conducted at the Meteorological Observatory Hohenpeissenberg (MOHP), Germany, applying a thermodesorption-GCxGC-FID system. The measured VOCs were compared to GC-MS measurements routinely conducted at the MOHP as well as to PTR-MS measurements. Furthermore, a compressed ambient air standard was measured from three different gas chromatographic instruments and the results were compared. With few exceptions, the in-situ, as well as the standard measurements, revealed good agreement between the individual instruments. Diurnal cycles were observed, with differing patterns for the biogenic and the anthropogenic compounds. The variability-lifetime relationship of compounds with atmospheric lifetimes from a few hours to a few days in presence of O3 and OH was examined. It revealed a weak but significant influence of chemistry on these short-lived VOCs at the site. The relationship was also used to estimate the average OH radical concentration during the campaign, which was compared to in-situ OH measurements (1.7 x 10^6 molecules/cm^3, 0.071 ppt) for the first time. The OH concentration ranging from 3.5 to 6.5 x 10^5 molecules/cm^3 (0.015 to 0.027 ppt) obtained with this method represents an approximation of the average OH concentration influencing the discussed VOCs from emission to measurement. Based on these findings, the average concentration of the nighttime NO3 radicals was estimated using the same approach and found to range from 2.2 to 5.0 x 10^8 molecules/cm^3 (9.2 to 21.0 ppt). During the MINATROC field campaign, in-situ ambient air measurements with the GCxGC-FID were conducted at Tenerife, Spain. Although the station is mainly situated in the free troposphere, local influences of anthropogenic and biogenic VOCs were observed. Due to a strong dust event originating from Western Africa it was possible to compare the mixing ratios during normal and elevated dust loading in the atmosphere. The mixing ratios during the dust event were found to be lower. However, this could not be attributed to heterogeneous reactions as there was a change in the wind direction from northwesterly to southeasterly during the dust event.

The release of zinc and lead from mine tailings

Mining and processing of metal ores are important causes of soil and groundwater contamination in many regions worldwide. Metal contaminations are a serious risk for the environment and human health. The assessment of metal contaminations in the soil is therefore an important task. A common approach to assess the environmental risk emanating from inorganic contaminations to soil and groundwater is the use of batch or column leaching tests. In this regard, the suitability of leaching tests is a controversial issue. In the first part of this work the applicability and comparability of common leaching tests in the scope of groundwater risk assessment of inorganic contamination is reviewed and critically discussed. Soil water sampling methods (the suction cup method and centrifugation) are addressed as an alternative to leaching tests. Reasons for limitations of the comparability of leaching test results are exposed and recommendations are given for the expedient application of leaching tests for groundwater risk assessment. Leaching tests are usually carried out in open contact with the atmosphere disregarding possible changes of redox conditions. This can affect the original metal speciation and distribution, particularly when anoxic samples are investigated. The influence of sample storage on leaching test results of sulfide bearing anoxic material from a former flotation dump is investigated in a long-term study. Since the oxidation of the sulfide-bearing samples leads to a significant overestimation of metal release, a feasible modification for the conduction of common leaching tests for anoxic material is proposed, where oxidation is prevented efficiently. A comparison of leaching test results to soil water analyzes have shown that the modified saturation soil extraction (SSE) is found to be the only of the tested leaching procedures, which can be recommended for the assessment of current soil water concentrations at anoxic sites if direct investigation of the soil water is impossible due to technical reasons. The vertical distribution and speciation of Zn and Pb in the flotation residues as well as metal concentrations in soil water and plants were investigated to evaluate the environmental risk arising from this site due to the release of metals. The variations in pH and inorganic C content show an acidification of the topsoil with pH values down to 5.5 in the soil and a soil water pH of 6 in 1 m depth. This is due to the oxidation of sulfides and depletion in carbonates. In the anoxic subsoil pH conditions are still neutral and soil water collected with suction cups is in equilibrium with carbonate minerals. Results from extended x-ray absorption fine-structure (EXAFS) spectroscopy confirm that Zn is mainly bound in sphalerite in the subsoil and weathering reactions lead to a redistribution of Zn in the topsoil. A loss of 35% Zn and S from the topsoil compared to the parent material with 10 g/kg Zn has been observed. 13% of total Zn in the topsoil can be regarded as mobile or easily mobilizable according to sequential chemical extractions (SCE). Zn concentrations of 10 mg/L were found in the soil water, where pH is acidic. Electron supply and the buffer capacity of the soil were identified as main factors controlling Zn mobility and release to the groundwater. Variable Pb concentrations up to 30 ��g/L were observed in the soil water. In contrast to Zn, Pb is enriched in the mobile fraction of the oxidized topsoil by a factor of 2 compared to the subsoil with 2 g/kg Pb. 80% of the cation exchange capacity in the topsoil is occupied by Pb. Therefore, plant uptake and bioavailability are of major concern. If the site is not prevented from proceeding acidification in the future, a significant release of Zn, S, and Pb to the groundwater has to be expected. Results from this study show that the assessment of metal release especially from sulfide bearing anoxic material requires an extensive comprehension of leaching mechanisms on the one hand and on weathering processes, which influence the speciation and the mobility of metals, on the other hand. Processes, which may change redox and pH conditions in the future, have to be addressed to enable sound decisions for soil and groundwater protection and remediation.

Die Rolle der Globalstrahlung im Klimasystem S��dwestdeutschlands

Die Untersuchungen umfassen die Periode 1981 ��� 2000 und basieren haupts��chlich auf Daten des Deutschen Wetterdienstes (DWD). Relativwerte der Globalstrahlung beziehen sich auf die Rayleigh-Atmosphäre. Das Regressionsmodell nach Angstr��m erm��glicht die Erweiterung des Me��netzes. In linearer und nichtlinearer Regression und Korrelation ist die Globalstrahlung entweder abh��ngige (Sonnenscheindauer, Bew��lkung) oder unabh��ngige Variable (Lufttemperatur, Bodentemperatur). Ihre Intensit��t in Abh��ngigkeit von Gro��wetterlagen, Gro��wettertypen und Luftmassen wird diskutiert. Diesbez��glich werden mit der Linearen Diskriminanzanalyse ��hnliche Gro��wetterlagen und Stationen in signifikant unterschiedenen Gruppen zusammengefa��t, getrennt nach Sommer- und Winterhalbjahr. Abh��ngig von der Zeit betrachtet, enthalten Globalstrahlung, direkte und diffuse Sonnenstrahlung, Lufttemperatur, Bew��lkung und Niederschlag signifikante zyklische Variationen, die gegebenenfalls klimatologisch relevant sind. Weiteren Aufschlu�� ergeben deshalb die Zeitreihenanalysen. Autokorrelation-Spektralanalysen (ASA) der genannten Variablen werden in integrierten Spektren dargestellt. Hinweise auf die zeitliche Konstanz signifikanter Varianzmaxima enthalten die Spektren der dynamischen (gleitenden) ASA.

Characterization of inclusions and their distribution in natural and artificial samples by synchrotron cryo-micro-tomography (SCXRT)

Zur geometrischen Vermessung und Beschreibung von Einschl��ssen in nat��rlichen sowie im Labor geschaffenen Eispartikeln wurde ein neuartiger Versuchaufbau an der Tomographie-Endstation der Material Science Beam Line an der Swiss Light Source (SLS, Paul Scherrer Institut, Villigen, Schweiz) entwickelt. Dieser besteht aus einer Plexiglas-Tasse und einem doppelwandigen Kaptonfolien-K��fig, der wiederum auf die D��se eines CryojetXL (Oxford Instruments) montiert wurde. Abgesehen von dem hohen Ma�� an Flexibilit��at bez��uglich der Installation erlaubt es dieser Aufbau, die Temperatur des Experiments mit einer Genauigkeit von �� 1 K ��ber einen Bereich von 271 K bis 220 K zu regeln. In den hier beschriebenen Experimenten wurde eine r��umliche Aufl��sung von 1.4 ��m erzielt.

Diffusivity and enzymatic activity control the exchange of carbonyl sulfide (COS) between soils and the atmosphere

Carbonylsulfid (COS) ist eines der stabilsten reduzierten schwefelhaltigen Spurengase in der Atmosphäre. In der gut durchmischten Troposph��re bewegt sich seine Konzentration um 500 ppt. COS spielt eine wichtige Rolle in der Produktion von stratosph��rischem Aerosol und im Ozon Zyklus. Dieses Spurengas hat eine Vielfalt an nat��rlichen und anthropogenen Quellen, denen gleichstarke Senken, darunter die dominanten wie Vegetation und Boden, gegen��ber stehen. Die St��rke der Senken ist trotz langj��hriger Forschungen immer noch Gegenstand der Diskussionen. Daher ist es wichtig die kontrollierenden Parameter zu charakterisieren. Alle Austauschmessungen vor 1990 vermuteten B��den als Quelle von COS, was aber durch Castro and Galloway (1991) klar widerlegt wurde. Heute werden B��den in Erg��nzung zur Vegetation grunds��tzlich als Senke betrachtet. Vor diesem Hintergrund wurden Bodenproben auf den Austausch von Carbonylsulfid mit der Atmosphäre unter verschiedenen Umgebungsbedingungen untersucht. Drei Ackerb��den aus Deutschland, China und Finnland und zwei Waldb��den aus Sibirien und Surinam konnten parametrisiert werden in Relation zur atmosph��rischen Umgebungskonzentration, Temperatur und Bodenfeuchte (WC). Neben Umgebungskonzentration und Bodenfeuchte, scheinen Bodenstruktur und enzymatische Aktivit��t die Richtung und Gr����e des Austauschflusses zu kontrollieren. Die ��bereinstimmenden Optima f��r boreale B��den in Relation zum wassergef��llten Porenvolumen des Bodens (WFPS) und die Linearit��t zwischen Depositionsgeschwindigkeit (Vd) und Bulk density lassen auf eine Dominanz der Abh��ngigkeit der COS-Aufnahme von der durch WFPS bestimmten Diffusionsf��higkeit schlie��en. WFPS ist abh��ngig von WC, Bodenstruktur und Bodenporosit��t. In Erg��nzung zu diesen eher physikalischen Parametern konnte die Carboanhydrase (CA) als kontrollierendes Enzym in B��den identifiziert werden. Erste Versuche zur direkten Bestimmung der CA in den untersuchten B��den erlaubten eine erste, aber noch sehr ungenaue Absch��tzung der Enzymaktivit��t.

Quantifying the OH radical by global scale NMHC measurements from the NOAA - ESRL cooperative flask sampling network

Summary PhD Thesis Jan Pollmann: This thesis focuses on global scale measurements of light reactive non-methane hydrocarbon (NMHC), in the volatility range from ethane to toluene with a special focus on ethane, propane, isobutane, butane, isopentane and pentane. Even though they only occur at the ppt level (nmol mol-1) in the remote troposphere these species can yield insight into key atmospheric processes. An analytical method was developed and subsequently evaluated to analyze NMHC from the NOAA ��� ERSL cooperative air sampling network. Potential analytical interferences through other atmospheric trace gases (water vapor and ozone) were carefully examined. The analytical parameters accuracy and precision were analyzed in detail. It was proven that more than 90% of the data points meet the Global Atmospheric Watch (GAW) data quality objective. Trace gas measurements from 28 measurement stations were used to derive the global atmospheric distribution profile for 4 NMHC (ethane, propane, isobutane, butane). A close comparison of the derived ethane data with previously published reports showed that northern hemispheric ethane background mixing ratio declined by approximately 30% since 1990. No such change was observed for southern hemispheric ethane. The NMHC data and trace gas data supplied by NOAA ESRL were used to estimate local diurnal averaged hydroxyl radical (OH) mixing ratios by variability analysis. Comparison of the variability derived OH with directly measured OH and modeled OH mixing ratios were found in good agreement outside the tropics. Tropical OH was on average two times higher than predicted by the model. Variability analysis was used to assess the effect of chlorine radicals on atmospheric oxidation chemistry. It was found that Cl is probably not of significant relevance on a global scale.

Chemie an funktionalen Polymer-Opalen

In dieser Arbeit wird die Herstellung und Anwendung von funktionalen Polymer-Opalen beschrieben. F��r die Synthese von funktionalen monodipsersen Kolloiden, den Bausteinen der Opale, wird die emulgatorfreie Emulsionspolymerisation (SFEP) verwendet. Je nach einzubauendem funktionalem Molek��l werden verschiedene Varianten der SFEP verwendet, wie z. B. Homopolymerisation, Copolymerisation, Polymerisation mit Fremdstoffen und die Herstellung von Kern-Schale-Kolloiden. Die so hergestellten monodispersen Kolloide formen durch Selbstorganisation ��ber horizontale (Aufpipettieren, Rakeln, Spr��hen) oder vertikale Kristallisation (Ziehmaschine)hochqualitative k��nstliche Opale. Die eingebauten Funktionalit��ten ��ffnen den Weg zu einer Vielzahl von Anwendungen. ��ber die Spaltung von funktionalen Estergruppen kann eine lichtinduzierte Strukturierung durchgef��hrt werden. Der Einbau von Epoxidgruppen erm��glicht eine makroskopische Vernetzung wodurch die mechanische Stabilit��t der Struktur erh��ht wird. Der Einsatz von Reaktivestern kann zur Oberfl��chen- funktionalisierung verwendet werden. Durch Replizierung der Struktur zum inversen Opal k��nnen weitere funktionale Materialien eingef��hrt werden, was die Einsatzm��glichkeiten noch erweitert.

Iodine speciation in atmospheric aerosols in the marine boundary layer

Iodine chemistry plays an important role in the tropospheric ozone depletion and the new particle formation in the Marine Boundary Layer (MBL). The sources, reaction pathways, and the sinks of iodine are investigated using lab experiments and field observations. The aims of this work are, firstly, to develop analytical methods for iodine measurements of marine aerosol samples especially for iodine speciation in the soluble iodine; secondly, to apply the analytical methods in field collected aerosol samples, and to estimate the characteristics of aerosol iodine in the MBL. Inductively Coupled Plasma ��� Mass Spectrometry (ICP-MS) was the technique used for iodine measurements. Offline methods using water extraction and Tetra-methyl-ammonium-hydroxide (TMAH) extraction were applied to measure total soluble iodine (TSI) and total insoluble iodine (TII) in the marine aerosol samples. External standard calibration and isotope dilution analysis (IDA) were both conducted for iodine quantification and the limits of detection (LODs) were both 0.1 ��g L-1 for TSI and TII measurements. Online couplings of Ion Chromatography (IC)-ICP-MS and Gel electrophoresis (GE)-ICP-MS were both developed for soluble iodine speciation. Anion exchange columns were adopted for IC-ICP-MS systems. Iodide, iodate, and unknown signal(s) were observed in these methods. Iodide and iodate were separated successfully and the LODs were 0.1 and 0.5 ��g L-1, respectively. Unknown signals were soluble organic iodine species (SOI) and quantified by the calibration curve of iodide, but not clearly identified and quantified yet. These analytical methods were all applied to the iodine measurements of marine aerosol samples from the worldwide filed campaigns. The TSI and TII concentrations (medians) in PM2.5 were found to be 240.87 pmol m-3 and 105.37 pmol m-3 at Mace Head, west coast of Ireland, as well as 119.10 pmol m-3 and 97.88 pmol m-3 in the cruise campaign over the North Atlantic Ocean, during June ��� July 2006. Inorganic iodine, namely iodide and iodate, was the minor iodine fraction in both campaigns, accounting for 7.3% (median) and 5.8% (median) in PM2.5 iodine at Mace Head and over the North Atlantic Ocean, respectively. Iodide concentrations were higher than iodate in most of the samples. In the contrast, more than 90% of TSI was SOI and the SOI concentration was correlated significantly with the iodide concentration. The correlation coefficients (R2) were both higher than 0.5 at Mace Head and in the first leg of the cruise. Size fractionated aerosol samples collected by 5 stage Berner impactor cascade sampler showed similar proportions of inorganic and organic iodine. Significant correlations were obtained in the particle size ranges of 0.25 ��� 0.71 ��m and 0.71 ��� 2.0 ��m between SOI and iodide, and better correlations were found in sunny days. TSI and iodide existed mainly in fine particle size range (< 2.0 ��m) and iodate resided in coarse range (2.0 ��� 10 ��m). Aerosol iodine was suggested to be related to the primary iodine release in the tidal zone. Natural meteorological conditions such as solar radiation, raining etc were observed to have influence on the aerosol iodine. During the ship campaign over the North Atlantic Ocean (January ��� February 2007), the TSI concentrations (medians) ranged 35.14 ��� 60.63 pmol m-3 among the 5 stages. Likewise, SOI was found to be the most abundant iodine fraction in TSI with a median of 98.6%. Significant correlation also presented between SOI and iodide in the size range of 2.0 ��� 5.9 ��m. Higher iodate concentration was again found in the higher particle size range, similar to that at Mace Head. Airmass transport from the biogenic bloom region and the Antarctic ice front sector was observed to play an important role in aerosol iodine enhancement. The TSI concentrations observed along the 30,000 km long cruise round trip from East Asia to Antarctica during November 2005 ��� March 2006 were much lower than in the other campaigns, with a median of 6.51 pmol m-3. Approximately 70% of the TSI was SOI on average. The abundances of inorganic iodine including iodine and iodide were less than 30% of TSI. The median value of iodide was 1.49 pmol m-3, which was more than four fold higher than that of iodate (median, 0.28 pmol m-3). Spatial variation indicated highest aerosol iodine appearing in the tropical area. Iodine level was considerably lower in coastal Antarctica with the TSI median of 3.22 pmol m-3. However, airmass transport from the ice front sector was correlated with the enhance TSI level, suggesting the unrevealed source of iodine in the polar region. In addition, significant correlation between SOI and iodide was also shown in this campaign. A global distribution in aerosol was shown in the field campaigns in this work. SOI was verified globally ubiquitous due to the presence in the different sampling locations and its high proportion in TSI in the marine aerosols. The correlations between SOI and iodide were obtained not only in different locations but also in different seasons, implying the possible mechanism of iodide production through SOI decomposition. Nevertheless, future studies are needed for improving the current understanding of iodine chemistry in the MBL (e.g. SOI identification and quantification as well as the update modeling involving organic matters).

Interactions between the hydrological cycle and atmospheric chemistry

The land-atmosphere exchange of atmospheric trace gases is sensitive to meteorological conditions and climate change. It contributes in turn to the atmospheric radiative forcing through its effects on tropospheric chemistry. The interactions between the hydrological cycle and atmospheric processes are intricate and often involve different levels of feedbacks. The Earth system model EMAC is used in this thesis to assess the direct role of the land surface components of the terrestrial hydrological cycle in the emissions, deposition and transport of key trace gases that control tropospheric chemistry. It is also used to examine its indirect role in changing the tropospheric chemical composition through the feedbacks between the atmospheric and the terrestrial branches of the hydrological cycle. Selected features of the hydrological cycle in EMAC are evaluated using observations from different data sources. The interactions between precipitation and the water vapor column, from the atmospheric branch of the hydrological cycle, and evapotranspiration, from its terrestrial branch, are assessed specially for tropical regions. The impacts of changes in the land surface hydrology on surface exchanges and the oxidizing chemistry of the atmosphere are assessed through two sensitivity simulations. In the first, a new parametrization for rainfall interception in the densely vegetated areas in the tropics is implemented, and its effects are assessed. The second study involves the application of a soil moisture forcing that replaces the model calculated soil moisture. Both experiments have a large impact on the local hydrological cycle, dry deposition of soluble and insoluble gases, emissions of isoprene through changes in surface temperature and the Planetary Boundary Layer height. Additionally the soil moisture forcing causes changes in local vertical transport and large-scale circulation. The changes in trace gas exchanges affect the oxidation capacity of the atmosphere through changes in OH, O$_3$, NO$_x$ concentrations.

Soil biogenic emissions of nitric oxide from arid and semi-arid ecosystems

The biogenic production of NO in the soil accounts for between 10% and 40% of the global total. A large degree of the uncertainty in the estimation of the biogenic emissions stems from a shortage of measurements in arid regions, which comprise 40% of the earth���s land surface area. This study examined the emission of NO from three ecosystems in southern Africa which cover an aridity gradient from semi-arid savannas in South Africa to the hyper-arid Namib Desert in Namibia. A laboratory method was used to determine the release of NO as a function of the soil moisture and the soil temperature. Various methods were used to up-scale the net potential NO emissions determined in the laboratory to the vegetation patch, landscape or regional level. The importance of landscape, vegetation and climatic characteristics is emphasized. The first study occurred in a semi-arid savanna region in South Africa, where soils were sampled from 4 landscape positions in the Kruger National Park. The maximum NO emission occurred at soil moisture contents of 10%-20% water filled pore space (WFPS). The highest net potential NO emissions came from the low lying landscape positions, which have the largest nitrogen (N) stocks and the largest input of N. Net potential NO fluxes obtained in the laboratory were converted in field fluxes for the period 2003-2005, for the four landscape positions, using soil moisture and temperature data obtained in situ at the Kruger National Park Flux Tower Site. The NO emissions ranged from 1.5-8.5 kg ha-1 a-1. The field fluxes were up-scaled to a regional basis using geographic information system (GIS) based techniques, this indicated that the highest NO emissions occurred from the Midslope positions due to their large geographical extent in the research area. Total emissions ranged from 20x103 kg in 2004 to 34x103 kg in 2003 for the 56000 ha Skukuza land type. The second study occurred in an arid savanna ecosystem in the Kalahari, Botswana. In this study I collected soils from four differing vegetation patch types including: Pan, Annual Grassland, Perennial Grassland and Bush Encroached patches. The maximum net potential NO fluxes ranged from 0.27 ng m-2 s-1 in the Pan patches to 2.95 ng m-2 s-1 in the Perennial Grassland patches. The net potential NO emissions were up-scaled for the year December 2005-November 2006. This was done using 1) the net potential NO emissions determined in the laboratory, 2) the vegetation patch distribution obtained from LANDSAT NDVI measurements 3) estimated soil moisture contents obtained from ENVISAT ASAR measurements and 4) soil surface temperature measurements using MODIS 8 day land surface temperature measurements. This up-scaling procedure gave NO fluxes which ranged from 1.8 g ha-1 month-1 in the winter months (June and July) to 323 g ha-1 month-1 in the summer months (January-March). Differences occurred between the vegetation patches where the highest NO fluxes occurred in the Perennial Grassland patches and the lowest in the Pan patches. Over the course of the year the mean up-scaled NO emission for the studied region was 0.54 kg ha-1 a-1 and accounts for a loss of approximately 7.4% of the estimated N input to the region. The third study occurred in the hyper-arid Namib Desert in Namibia. Soils were sampled from three ecosystems; Dunes, Gravel Plains and the Riparian zone of the Kuiseb River. The net potential NO flux measured in the laboratory was used to estimate the NO flux for the Namib Desert for 2006 using modelled soil moisture and temperature data from the European Centre for Medium Range Weather Forecasts (ECMWF) operational model on a 36km x 35km spatial resolution. The maximum net potential NO production occurred at low soil moisture contents (<10%WFPS) and the optimal temperature was 25��C in the Dune and Riparian ecosystems and 35��C in the Gravel Plain Ecosystems. The maximum net potential NO fluxes ranged from 3.0 ng m-2 s-1 in the Riparian ecosystem to 6.2 ng m-2 s-1 in the Gravel Plains ecosystem. Up-scaling the net potential NO flux gave NO fluxes of up to 0.062 kg ha-1 a-1 in the Dune ecosystem and 0.544 kg h-1 a-1 in the Gravel Plain ecosystem. From these studies it is shown that NO is emitted ubiquitously from terrestrial ecosystems, as such the NO emission potential from deserts and scrublands should be taken into account in the global NO models. The emission of NO is influenced by various factors such as landscape, vegetation and climate. This study looks at the potential emissions from certain arid and semi-arid environments in southern Africa and other parts of the world and discusses some of the important factors controlling the emission of NO from the soil.

Untersuchungen zum Austausch von Stickstoffdioxid (NO 2) zwischen Pflanzen und Atmosphäre

Der Austausch der NO2-Konzentration zwischen der Atmosphäre und verschiedenen B��umen (Betula pendula, Fagus sylvatica, Quercus robur, Quercus ilex und Pinus sylvestris) wurde mit einer Dynamischen K��vette gemessen. Die NO2-Konzentrationen wurden mit einem CLD 780 TR Analysator in Verbindung mit einem PLC 762 gemessen. Die experimentellen Untersuchungen wurden im Dunkeln und unter zwei Lichtintensit��ts-Niveaus (PAR, 450 und 900 ��mol m-2 s-1) und sechs verschiedene NO2-Konzentrationen zwischen 0 - 5.0 ppb durchgef��hrt. Der stomat��re Einfluss wurde unter Einsatz des Hormons Abscisins��ure untersucht. Die Umgebungsparameter (Lufttemperatur und Luftfeuchtigkeit) wurden konstant gehalten. Die Daten zeigten klar und deutlich den dominanten Einfluss der jeweiligen Baumspezies auf die NO2-Konzentrationen innerhalb der K��vette. Die Ergebnisse dieser Arbeit belegen bei allen Spezies eine lineare Abh��ngigkeit der NO2-Austauschrate mit der NO2-Umgebungskozentration und mit der stomat��ren Leitf��higkeit. Das Vorhandensein eines Kompensationspunkt wird nicht best��tigt.

Polycyclic aromatic hydrocarbons (PAHs) in river bank soils

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous and found in the atmosphere, aquatic environment, sediments and soils. For environmental risk assessments and the allocation of the polluter it is important to know the PAH sources. PAH contamination sites are usually the result of anthropogenic processes. Three major sources are known: i) petroleum, including crude oil and its refined products and coals (petrogenic PAHs), ii) burning of organic matter (pyrogenic PAHs) and iii) transformation products of natural organic precursors present in the environment (diagenetic processes). In one case elevated PAH concentrations were found in river bank soils when building a retention area along the Mosel River. The source of the PAHs in this area was unclear and required the investigation of possible sources. To evaluate the PAH distribution along the Mosel River, a section of ~ 160 km along the river and a short section along the Saar River were investigated within this study. Concentrations of the ��16 EPA PAHs were as high as 81 mg kg-1 dry weight (dw). Additionally, coal particles were identified in some soils, which originated from mining activities in the Saarland region. PAH distribution patterns of the 16 EPA PAHs suggest a mainly pyrogenic origin and in some cases a mixture of pyrogenic and petrogenic origin. For a comprehensive investigation five sampling sites were selected. Two sites were located before the confluence of the Mosel and Saar River, one site at the confluence and two sites after the confluence. The examination included typical forensic methods such as PAH distribution patterns of 45 PAHs (including alkylated PAHs), calculation of PAH ratios, determination of PAH alkyl homologues, n-alkanes, principal component analysis (PCA) and coal petrography. The results revealed a mainly pyrogenic source at sampling sites before the confluence of the two rivers. At and after the confluence, a mixture of pyrogenic and petrogenic inputs were present. With the help of coal petrography, coal derived particles could be identified in these soils. Therefore, coal was suggested to be the petrogenic source. It could be shown that sites with diffuse sources of contaminants, like the bank soils of the Mosel River, are difficult to characterize. As previously mentioned for detailed source identifications, the use of various forensic methods is essential. Determination of PAH alkyl homologue series, biomarkers and isotopes are often recommended. Source identification was evaluated using three different methods (i.e. PAH distribution patterns of an extended PAH spectrum, PAH ratios and analyses of n-alkanes). It was assessed if these methods were sufficient for the initial steps in identifying sources of PAHs in selected samples, and if they could be used for decision-making purposes. Point- and non-point sources were identified by applying the three methods and it could be shown that these relatively simple methods are sufficient in determining the primary source. In a last step of this study two soils (one before the confluence of the Mosel and Saar rivers and one after the confluence), and one sediment of the Mosel River were evaluated by investigating the mutagenic potential of the soils and the sediment with a fluctuation version of the Ames-test. The study showed that coal bearing soils at the Mosel River do not exhibit a greater mutagenic potential than other soils or sediments without coal particles.

Massenspektrometrische Untersuchungen und Nachweise von organischen Hydroperoxiden und h��hermolekularen Verbindungen im biogenen sekund��ren organischen Aerosol

Atmosph��rische Aerosole beeinflussen den Strahlungshaushalt und damit das Klima der Erde. Dies geschieht sowohl direkt (Streuung und Absorption), als auch indirekt (Wolkenkondensationskeime). Das sekund��re organische Aerosol (SOA) bildet einen wichtigen Bestandteil des atmosph��rischen Aerosols. Seine Bildung erfolgt durch Reaktionen von Kohlenwasserstoffen mit atmosph��rischen Oxidationsmitteln (z.B. Ozon, OH-Radikalen). Eine Klasse dieser Kohlenwasserstoffe sind die Terpene. Sie werden in gro��en Mengen durch die Vegetation emittiert und gelten als wichtige Vorl��ufersubstanzen des biogenen SOAs. In den Reaktionen von Monoterpenen und Sesquiterpenen mit atmosph��rischen Reaktionspartnern wird eine gro��e Vielfalt an multifunktionellen Reaktionsprodukten gebildet, von denen bis heute nur ein Bruchteil identifiziert werden konnte. In der vorliegenden Arbeit soll im Speziellen die Bildung von organischen Peroxiden und oligomeren Verbindungen im biogenen SOA untersucht und Nachweise einzelner Molek��le erbracht werden.rnF��r eine Identifizierung von organischen Peroxiden aus der Oxidation einzelner Monoterpene und Sesquiterpene mit Ozon wurden die Reaktionsprodukte direkt in eine bei Atmosphärendruck arbeitende chemische Ionisationsquelle ��berf��hrt und massenspektrometrisch untersucht (online-APCI-MS). Hierdurch konnten organische Hydroperoxide in der Partikelphase nachgewiesen werden, welche sich durch eine signifikante Abspaltung von H2O2 im Tandem-Massenspektrum (MS/MS) auszeichneten. Des Weiteren sollte die Bildung von h��hermolekularen Verbindungen (���Dimere���) im SOA des ��-Pinens untersucht werden. Hierf��r wurden zun��chst die Reaktionsprodukte des Cyclohexens, das als einfache Modellverbindung des ��-Pinens dient, mittels online-APCI-MS und offline durch Fl��ssigkeitschromatographie und Elektrospray-Ionenfallenmassenspektrometrie (HPLC/ESI-MS) untersucht. Verschiedene Produkte der Cyclohexen-Ozonolyse konnten hierbei als Esterverbindungen identifiziert werden, wobei eigens synthetisierte Referenzsubstanzen f��r die Identifizierung verwendet wurden. In einem weiteren Experiment, indem gleichzeitig Cyclohexen und ��-Pinen mit Ozon umgesetzt wurden, konnten ebenfalls eine Bildung von h��hermolekularen Estern nachgewiesen werden. Es handelte sich hierbei um ���Mischester���, deren Struktur aus Reaktionsprodukten der beiden VOC-Vorl��ufermolek��le aufgebaut war. Durch diese neuen Erkenntnisse, ��ber die Bildung von Estern im SOA des Cyclohexens, wurden die Dimer-Bildung einer reinen ��-Pinen/Ozon-Reaktion online und offline massenspektrometrisch untersucht. Hier stellten sich als Hauptprodukte die Verbindungen mit m/z 357 und m/z 367 ([M-H]--Ionen) heraus, welche zudem erstmals auf einem Filter einer Realprobe aus Hyyti��l��, Finnland nachgewiesen werden konnten. Aufgrund ihrer Fragmentierung in MS/MS-Untersuchungen sowie den exakten Summenformeln aus FT-MS Messungen konnte f��r die Struktur der h��hermolekularen Verbindung mit m/z 367 ebenfalls ein Ester und f��r m/z 357 ein Peroxyhemiacetal vorgeschlagen werden. Die vorgeschlagene Struktur der Verbindung m/z 367 konnte im Anschluss ��ber eine Reaktion aus Hydroxypinons��ure mit Pins��ure best��tigt werden. Die Identifizierung der Esterverbindung des ��-Pinen-SOA erfolgte ebenfalls mit Hilfe von LC-MSn-Messungen.rnDie bisher diskutierten Ergebnisse, sowie die meisten in der Literatur beschriebenen Studien befassen sich jedoch mit einzelnen Vorl��uferverbindungen, im Gegensatz zu den komplexen SOA-Proben aus den Emissionen der Vegetation. Im Rahmen einer Messkampagne am Forschungszentrum J��lich erfolgte eine massenspektrometrische Charakterisierung (online-APCI-MS) des SOAs aus direkten VOC-Emissionen von Pflanzen. Durch einen Vergleich der Produktverteilung dieser erhalten online-Massenspektren mit denen aus den Reaktionen einzelner VOCs, konnten Aussagen ��ber die in den Reaktionen umgesetzten VOCs gemacht werden. Es konnte gezeigt werden, dass in stressbedingten Situationen die untersuchten Exemplare der Betula pendula (Birke) haupts��chlich Sesquiterpene, Picea abies (Fichte) eher Monoterpene und Eucalyptus (Eukalyptus) sowohl Sesquiterpene als auch Monoterpene emittieren. Um die atmosph��rischen Prozesse, die zur Bildung der Produkte im SOA f��hren vollst��ndig zu verstehen, m��ssen jedoch noch weitere Anstrengungen unternommen werden.rn

Reactive halogen compounds in the marine boundary layer: method developments and field measurements

Reactive halogen compounds are known to play an important role in a wide variety of atmospheric processes such as atmospheric oxidation capacity and coastal new particle formation. In this work, novel analytical approaches combining diffusion denuder/impinger sampling techniques with gas chromatographic���mass spectrometric (GC���MS) determination are developed to measure activated chlorine compounds (HOCl and Cl2), activated bromine compounds (HOBr, Br2, BrCl, and BrI), activated iodine compounds (HOI and ICl), and molecular iodine (I2). The denuder/GC���MS methods have been used to field measurements in the marine boundary layer (MBL). High mixing ratios (of the order of 100 ppt) of activated halogen compounds and I2 are observed in the coastal MBL in Ireland, which explains the ozone destruction observed. The emission of I2 is found to correlate inversely with tidal height and correlate positively with the levels of O3 in the surrounding air. In addition the release is found to be dominated by algae species compositions and biomass density, which proves the ���hot-spot��� hypothesis of atmospheric iodine chemistry. The observations of elevated I2 concentrations substantially support the existence of higher concentrations of littoral iodine oxides and thus the connection to the strong ultra-fine particle formation events in the coastal MBL.

Water-soluble organic compounds in air particulate matter analyzed by HPLC-DAD-MS and HPLC-MS/MS: abundance, sources and transformation of carboxylic acids, nitrophenols and nitrated proteins

Wasserl��sliche organische Verbindungen (WSOCs) sind Hauptbestandteile atmosph��rischer Aerosole, die bis zu ~ 50% und mehr der organischen Aerosolfraktion ausmachen. Sie k��nnen die optischen Eigenschaften sowie die Hygroskopizit��t von Aerosolpartikeln und damit deren Auswirkungen auf das Klima beeinflussen. Dar��ber hinaus k��nnen sie zur Toxizit��t und Allergenit��t atmosph��rischer Aerosole beitragen.In dieser Studie wurde Hochleistungsfl��ssigchromatographie gekoppelt mit optischen Diodenarraydetektion und Massenspektrometrie (HPLC-DAD-MS und HPLC-MS/MS) angewandt, um WSOCs zu analysieren, die f��r verschiedene Aerosolquellen und -prozesse charakteristisch sind. Niedermolekulare Carbons��uren und Nitrophenole wurden als Indikatoren f��r die Verbrennung fossiler Brennstoffe und die Entstehung sowie Alterung sekund��rer organischer Aerosole (SOA) aus biogenen Vorl��ufern untersucht. Protein-Makromolek��le wurden mit Blick auf den Einfluss von Luftverschmutzung und Nitrierungsreaktionen auf die Allergenit��t prim��rer biologischer Aerosolpartikel ��� wie Pollen und Pilzsporen ��� untersucht.rnFilterproben von Grob- und Feinstaubwurden ��ber ein Jahr hinweg gesammelt und auf folgende WSOCs untersucht: die Pinen-Oxidationsprodukte Pins��ure, Pinons��ure und 3-Methyl-1,2,3-Butantricarbons��ure (3-MBTCA) sowie eine Vielzahl anderer Dicarbons��uren und Nitrophenole. Saisonale Schwankungen und andere charakteristische Merkmale werden mit Blick auf Aerosolquellen und -senken im Vergleich zu Daten anderen Studien und Regionen diskutiert. Die Verh��tlnisse von Adipins��ure und Phthals��ure zu Azelains��ure deuten darauf hin, dass die untersuchten Aerosolproben haupts��chlich durch biogene Quellen beeinflusst werden. Eine ausgepr��gte Arrhenius-artige Korrelation wurde zwischen der 3-MBTCA-��Konzentration und der inversen Temperatur beobachtet (R2 = 0.79, Ea = 126��10 kJ mol-1, Temperaturbereich 275���300 K). Modellrechnungen zeigen, dass die Temperaturabh��ngigkeit auf eine Steigerung der photochemischen Produktionsraten von 3-MBTCA durch erh��hte OH-Radikal-Konzentrationen bei erh��hten Temperaturen zur��ckgef��hrt werden kann. Im Vergleich zur chemischen Reaktionskinetik scheint der Einfluss von Gas-Partikel-Partitionierungseffekten nur eine untergeordnete Rolle zu spielen. Die Ergebnisse zeigen, dass die OH-initiierte Oxidation von Pinos��ure der geschwindigkeitsbestimmende Schritt der Bildung von 3-MBTCA ist. 3-MBTCA erscheint somit als Indikator f��r die chemische Alterung von biogener sekund��rer organischer Aerosole (SOA) durch OH-Radikale geeignet. Eine Arrhenius-artige Temperaturabh��ngigkeit wurde auch f��r Pin��ure beobachtet und kann durch die Temperaturabh��ngigkeit der biogenen Pinen-Emissionen als geschwindigkeitsbestimmender Schritt der Pins��ure-Bildung erkl��rt werden (R2 = 0.60, Ea = 84��9 kJ mol-1).rn rnF��r die Untersuchung von Proteinnitrierungreaktionen wurde nitrierte Protein��standards durch Fl��ssigphasenreaktion von Rinderserumalbumin (BSA) und Ovalbumin (OVA) mit Tetranitromethan (TNM) synthetisiert.Proteinnitrierung erfolgt vorrangig an den Resten der aromatischen Aminos��ure Tyrosin auf, und mittels UV-Vis-Photometrie wurde der Proteinnnitrierungsgrad (ND) bestimmt. Dieser ist definiert als Verh��ltnis der mittleren Anzahl von Nitrotyrosinresten zur Tyrosinrest-Gesamtzahl in den Proteinmolek��len. BSA und OVA zeigten verschiedene Relationen zwischen ND und TNM/Tyrosin-Verh��ltnis im Reaktionsgemisch, was vermutlich auf Unterschiede in den L��slichkeiten und den molekularen Strukturen der beiden Proteine zur��ck zu f��hren ist.rnDie Nitrierung von BSA und OVA durch Exposition mit einem Gasgemisch aus Stickstoffdioxid (NO2) und Ozon (O3) wurde mit einer neu entwickelten HPLC-DAD-��Analysemethode untersucht. Diese einfache und robuste Methode erlaubt die Bestimmung des ND ohne Hydrolyse oder Verdau der untersuchten Proteine und ern��glicht somit eine effiziente Untersuchung der Kinetik von Protein��nitrierungs-Reaktionen. F��r eine detaillierte Produktstudien wurden die nitrierten Proteine enzymatisch verdaut, und die erhaltenen Oligopeptide wurden mittels HPLC-MS/MS und Datenbankabgleich mit hoher Sequenz��bereinstimmung analysiert. Die Nitrierungsgrade individueller Nitrotyrosin-Reste (NDY) korrelierten gut mit dem Gesamt-Proteinnitrierungsgrad (ND), und unterschiedliche Verh��ltnisse von NDY zu ND geben Aufschluss ��ber die Regioselektivit��t der Reaktion. Die Nitrierungmuster von BSA und OVA nach Beahndlung mit TNM deuten darauf hin, dass die Nachbarschaft eines negativ geladenen Aminos��urerestes die Tyrosinnitrierung f��rdert. Die Behandlung von BSA durch NO2 und O3 f��hrte zu anderend Nitrierungemustern als die Behandlung mit TNM, was darauf hindeutet, dass die Regioselektivit��t der Nitrierung vom Nitrierungsmittel abh��ngt. Es zeigt sich jedoch, dass Tyrosinreste in Loop-Strukturen bevorzugt und unabh��ngig vom Reagens nitriert werden.Die Methoden und Ergebnisse dieser Studie bilden eine Grundlage f��r weitere, detaillierte Untersuchungen der Reaktionskinetik sowie der Produkte und Mechanismen von Proteinnitrierungreaktionen. Sie sollen helfen, die Zusammenh��nge zwischen verkehrsbedingten Luftschadstoffen wie Stickoxiden und Ozon und der Allergenit��t von Luftstaub aufzukl��ren.rn