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Das Thema dieser Arbeit war die Untersuchung der natürlichen Variationen von den zwei primordialen Uranisotopen (238U und 235U) mit einem Schwerpunkt auf Proben, die (1) die kontinentale Kruste und ihre Verwitterungsprodukte (d.h. Granite, Shales und Flusswasser) repräsentieren, (2) Produkte der hydrothermalen Alteration vom mittelozeanischen Rücken widerspiegeln (d.h. alterierte Basalte, Karbonatgänge und hydrothermales Wasser) und (3) aus abgegrenzten euxinischen Becken (d.h. Proben aus der Wassersäule und den dazugehörigen Sedimenten) stammen. Das allgemeine Ziel war das Verständnis, unter welchen Bedingungen und Mechanismen eine Fraktionierung der zwei häufigsten Uranisotope (238U und 235U) in der Natur erfolgt, zu verbessern.
Die untersuchten Haupt- und Nebenflüsse unterscheiden sich sowohl in Ihrer Urankonzentration (c(U)) als auch in Ihrer Uranisotopenzusammensetzung (δ238U), wobei die Nebenflüsse eine geringere Urankonzentration (0.87 nmol/kg bis 3.08 nmol/kg) und eine schwerere Uranisotopenzusammensetzung aufweisen (-0.29 ‰ bis +0.01 ‰ im δ238U) im Vergleich zu den Hauptflüssen (c(U) = 5.19 nmol/kg bis 11.69 nmol/kg und d238U = -0.31 ‰ bis +0.13 ‰) aufweisen. Die untersuchten Gesteinsproben fallen alle in einen recht schmalen Bereich von δ238U, zwischen -0.45 ‰ und -0.21 ‰, mit einem Durchschnittswert von -0.30 ‰ ± 0.04 ‰ (doppelte Standardabweichung). Deren Uranisotopenvariationen sind unabhängig von der Urankonzentration (11.8 µg/g bis 1.3 µg/g), dem Alter (3.80 Ga bis 328 Ma), der Probenlokalität und Grad der Differenzierung. Basierend auf den Ergebnissen der Hauptflüsse, die die Uranhauptquelle für den Ozean darstellen, schlagen wir für zukünftige Berechnungen in der Massenbilanz des Urans einen neuen Wert als beste Abschätzung für die Quelle des Urans im Ozean vor, δ238U = -0.23 ‰.
Die Produkte der hydrothermalen Alteration, alterierte Basalte und Kalziumkarbonatgänge, zeigten etwas stärkere Isotopenvariationen (δ238U zwischen -0.63 ‰ und +0.27 ‰) als erwartet und die hydrothermalen Fluide wiesen eine etwas leichtere Uranisotopenzusammensetzung als Meerwasser ((-0.43 ± 0.25) ‰ vs. (-0.37 ± 0.03) ‰) auf. Diese Ergebnisse sind in Übereinstimmung mit einem Modell, dass annimmt, dass die beobachtete Isotopenfraktionierung hauptsächlich ein Ergebnis von Redoxprozessen ist, z.B. die partielle Reduktion von löslichem UVI aus dem Meerwasser während der hydrothermalen Alteration, was zu einer Anreicherung der schweren Uranisotope in der reduzierten Uranspezies (UIV) führt und 2) das bevorzugte Entfernen von UIV aus den hydrothermalen Fluid und der Einbau in die alterierte ozeanische Kruste. Durch diesen Prozess wird das hydrothermale Fluid an schweren Uranisotopen verarmt und somit würden auch die alterierten Basalte und Karbonate ein niedriges δ238U aufweisen, wenn sie mit dem isotopisch leichten hydrothermalen Fluid in Kontakt gekommen sind.
Die Untersuchung von Wasser- und Sedimentproben aus der Ostsee und dem anoxischen Kyllaren Fjord (Norwegen) auf deren Uran- und Mo-Isotopenzusammensetzung zeigte, dass die Uranisotopenzusammensetzung der Sedimente abhängt von (1) dem Ausmaß des Uranaustrags aus der Wassersäule (in einer ähnlichen Art und Weise wie bei den Molybdänisotopen) und (2) der Sedimentationsrate, d.h. der Fraktion von authigenem- relativ zum dedritischen Uran in den Sedimenten. Aufgrund der hohen Sedimentationsrate zeigen die Sedimente aus dem Kyllaren Fjord nur eine moderate authigene Urananreicherung und eine leichtere Uranisotopenzusammensetzung als Sedimente aus dem Schwarzen Meer. In den anoxischen Becken der Ostsee erfolgt dagegen eine starke Mo- und schwache U-Isotopenfraktionierung zwischen Wasser und Sediment. Durch die regelmäßigen auftretenden Spülereignisse mit sauerstoffreichem Wasser wurden vermutlich die ursprünglichen anoxischen Mo- und U-Isotopensignaturen der Sedimente verändert. Demzufolge müssen die Sedimente durchgehend anoxischen Bedingungen ausgesetzt sein, um eine Mo- und U-Isotopensignatur von den Redoxbedingungen während der Ablagerungen zu speichern.
Der Vergleich zwischen Molybdän- und Uranisotopen in der Ostsee und dem anoxischen Kyllaren Fjord zeigte, dass sich Uran- und Molybdänisotope in stark euxinischen Wassersäulen (c(H2S) > 11 µmol/L) entgegengesetzt verhalten. Dementsprechend ergänzen sich die beiden Isotopensysteme und können genutzt werden, um die Ablagerungsbedingungen in abgeschlossenen Becken und die Redoxentwicklung des Paläoozeans zu untersuchen.
Die Anwendung der WKB-Theorie zur Simulation der schwach nichtlinearen Dynamik von Schwerewellen
(2014)
Es ist schon seit Längerem bekannt, dass Schwerewellen die Zirkulation der mittleren Atmosphäre beeinflussen. Sie werden fast ausschließlich in der Troposphäre durch Prozesse wie Gebirgsüberströmung, Konvektionen, Frontogenese etc. erzeugt. Sie propagieren von ihrem Entstehungsort in der Troposphäre in die höheren Schichten der Atmosphäre und transportieren dabei ihre Energie und ihren Impuls. Unter der Voraussetzung, dass die Energie von Schwerewellen erhalten bleibt und die Dichte der Atmosphäre mit der Höhe exponentiell abnimmt, wächst die Amplitude der Schwerewellen so stark an, dass sie brechen und ihren Impuls in Stratosphäre und Mesosphäre deponieren. Als Folge davon beeinflussen Schwerewellen die großräumige Zirkulation der Atmosphäre und sind damit ein wichtiges Bindeglied, welches die Troposphäre mit anderen Atmosphärenbereichen verbindet. Folglich ist es wichtig, dass die Klima- und Wettermodelle in der Lage sind, die Schwerewellendynamik zu beschreiben. Bedauerlicherweise können diese Modelle nicht das komplette Schwerewellenspektrum auflösen. Somit müssen Schwerewellen in den Modellen parametrisiert werden. Viele Parametrisierungsschemen basieren auf Wentzel-Kramer-Brillouin(WKB)-Theorie. Die WKB-Gleichungen, die sogenannten Strahlengleichungen, beschreiben die räumliche und zeitliche Variation der Welleneigenschaften wie Wellenzahl, Wellenamplitude und Wellenfrequenz entlang der Charakteristiken, welche durch die lokale Gruppengeschwindigkeit vorgegeben sind. Die numerische Modelle, die auf den Strahlengleichungen basieren, werden als Strahlenmodelle bezeichnet. In Strahlenmodellen werden Schwerewellen durch Wellenteilchen dargestellt. Zur Zeit verwenden die Strahlenmodelle stationäre Strahlengleichungen, da die Wechselwirkung eines zeitabhängigen Schwerewellenfeldes mit einem zeit- und ortsabhängigen Hintergrund zu Problemen in Strahlenmodellen führen kann. Die Strahlengleichungen basieren auf der Annahme, dass sich nie zwei Wellenteilchen mit den unterschiedlichen Welleneigenschaften an einer Position befinden können. Wenn an einer Position zwei Wellenteilchen mit den unterschiedlichen Wellenzahlen befinden, entsteht sogenannte Kaustik: ein Punkt im Raum, an dem sich mehrere Charakteristiken kreuzen. Wenn eine Kaustik entsteht, kann die Wellenamplitude nicht mehr bestimmt werden. Ziel der vorliegenden Arbeit ist es mithilfe der WKB-Theorie die Ausbreitung von Schwerewellenpaketen in einer raum- und zeitabhängigen Hintergrundströmung zu beschreiben und ein numerisches Modell zu entwickeln, welches die Schwerewellen parametrisieren und ihre Wechselwirkung mit der raum- und zeitabhängigen Hintergrundströmung beschreiben kann.
Einfachheitshalber wird in dieser Arbeit nur die Wechselwirkung zwischen horizontal periodischen, vertikal lokalisierten Schwerewellenpaketen und der raum- und zeitabhängigen Hintergrundströmung betrachtet.
Interpretation magnetotellurischer Messungen auf Island und 3D-Modellierungen des Island-Plumes
(2014)
Die Lage und der geologische Aufbau Islands sind eine einmalige geologische und geophysikalische Besonderheit - nur hier liegt der Mittelatlantische Rücken deutlich oberhalb des Meeresspiegels. Eine Theorie ist, dass unter Island ein sogenannter Hotspot existiert - ein aufsteigender Mantelplume (oder eine andere Temperatur- und Schmelzanomalie). Das bedeutet, dass die Tektonik, die Petrologie und die (geo)physikalischen Parameter von der Wechselwirkung der Meeresbodenspreizung mit dem aufsteigenden Mantelplume bestimmt werden. Die magnetotellurischen Untersuchungen auf Island und die magnetotellurischen Modelle der vorliegenden Arbeit lassen sich nach Zieltiefen unterteilen. Im ersten Teil steht vor allem die Untersuchung der Leitfähigkeitsstruktur des oberen Erdmantels im Vordergrund, wobei der Schwerpunkt auf Modellstudien liegt. Hier wird die Theorie des aufsteigenden Mantelplumes aufgegriffen und hinsichtlich der Möglichkeiten der Magnetotellurik (MT) diesen zu detektieren, untersucht. In dieser Arbeit werden deshalb verschiedene synthetische 3D-Modelle untersucht. Diese sollen klären, unter welchen Bedingungen, d.h. bei welcher Tiefenlage, Ausdehnung und Leitfähigkeit, ein Mantelplume in der Magnetotellurik messbare Signale liefert. Da Temperatur und Schmelzanteil hierbei eine entscheidende Rolle spielen, werden auch Ergebnisse von geodynamischen Modellierungen verwendet. Die verschiedenen Modellierungen machen deutlich, dass der Plume in Modellen mit maximal 1% Schmelzanteil nur sehr schlecht mit der MT aufgelöst werden kann. Ein weiteres Problem ist die relativ geringe laterale Ausdehnung des Bereichs hoher Leitfähigkeit. Insbesondere bei Berücksichtigung des Krustenleiters liegen die Effekte des Plumes im Bereich der Messfehler bei realen Daten. Erst bei 3% Schmelzanteil im Plume ergeben sich Charakteristiken in den Sondierungskurven, die eindeutig dem Plume zugeordnet werden können. Im zweiten Teil liegt das Augenmerk auf der Leitfähigkeitsstruktur der isländischen Kruste, für deren Untersuchung ca. 200 Datensätze aus zahlreichen deutsch-isländischen Messkampagnen zur Verfügung stehen. In dieser Arbeit werden sie ganzheitlich ausgewertet und interpretiert. Hier steht im Speziellen der in verschiedenen früheren Untersuchungen gefundene gute Leiter in ca. 10 km Tiefe im Vordergrund. Seine Ausdehnung, Tiefenlage und Leitfähigkeit sowie laterale Änderungen werden genauer untersucht. Dazu werden aus den gemessenen Daten und den daraus ermittelten magnetotellurischen Impedanztensoren nicht nur die Sondierungskurven, sondern weitere Parameter wie Phasentensoren und Rotationsinvarianten abgeleitet und diskutiert. Um einen Überblick über die räumliche Verteilung der Untergrundstrukturen zu erhalten, werden die einzelnen Messpunkte charakterisiert und Stationen mit ähnlichem Verhalten in Gruppen zusammengefasst. 1D- und 2D- Inversionsmodelle liefern einen direkten Hinweis auf die Leitfähigkeitsverteilung. Diese zeigt ausgeprägte laterale Änderungen. Aus den 2D-Modellen ergeben sich Hinweise, die darauf schließen lassen, dass diese Zone niedrigen Widerstands nicht durchgängig oder geschlossen sein muss, um die gemessenen Daten zu erklären. Der gute Leiter scheint weniger mit der Aufwölbung durch den vermuteten Mantelplume oder eine andere tiefer liegende Schmelzanomalie korreliert zu sein. Die lateralen und vertikalen Variationen lassen auf einen Zusammenhang mit den Vulkansystemen auf Island schließen. Darauf deuten auch die Induktionsvektoren hin, die lateral betrachtet stark variieren. Ein weiteres Ergebnis ist das Fehlen dieses Krustenleiters in einem mindestens 20km breiten Streifen entlang der Südküste.
Gridded maps of meteorological variables are needed for the evaluation of weather and climate models and for climate change monitoring. In order to produce them, values at locations where no observing stations are available need to be estimated from point-wise observations. For the interpolation of meteorological observations deterministic and stochastic methods are often combined. Deterministic methods can account for ancillary information such as elevation, continentality or satellite observations. Stochastic methods such as kriging reproduce observed values at the station locations and also account for spatial variability. In the first two studies of this thesis, a flexible interpolation method for the gridding of locally observed daily extreme temperatures is developed that also provides an optimal estimate of the interpolation ncertainty. In the third study, an observational dataset is created using this interpolation method and then applied to evaluate a climate simulation for Africa.
In the first study, the Regression-Kriging-Kriging (RKK) method is tested for the interpolation of daily minimum and maximum temperatures (Tmin and Tmax) in different regions in Europe. RKK accounts for elevation, continentality index and zonal mean temperature and is applicable in regions of differing station density and climate. The accuracy of RKK is compared to Inverse Distance Weighting, a common deterministic interpolation method, and to Ordinary Kriging, a common stochastic interpolation method. The first step in RKK is to use regression kriging, in which multiple linear regression accounts for topographical effects on the temperature field and kriging minimizes the regression error, to interpolate climatological means. In the second step daily deviations from the monthly climatology are interpolated using simple kriging. Owing to the large climatological differences across the investigation area the interpolation is performed in homogeneous subregions defined according to the Köppen-Geiger climate classification. Cross validation demonstrates the superiority of RKK over the simpler algorithms in terms of accuracy and preservation of spatial variability. The interpolation performance however strongly varies across Europe, being considerably higher over Central Europe (highest station density) than over Greenland (few stations along the coast line). This illustrates the strong impact of the station density on the accuracy of the interpolation result. Satellites provide comprehensive observations of climate variables such as land surface temperature (LST) and cloud cover (CC). However, LST is associated with high uncertainty (standard error ~ 1-2°C), preventing its direct application in meteorology and climatology. The second study investigates the usefulness of LST and CC as predictors for the gridding of daily Tmin and Tmax. The RKK algorithm is compared with similar interpolation methods that apply LST and CC in addition to the predictors used with the RKK algorithm. The investigation is conducted in two regions, Central Europe and the Iberian Peninsula, which differ strongly in average cloud cover (Central Europe is approximately 30% cloud free and the Iberian Peninsula approximately 60 % cloud free). RKKLST (in which monthly mean LST is used as an additional predictor) yields for Central Europe no clear improvement over RKK, yet it reduces the interpolation error over the Iberian Peninsula. This finding can be explained by the higher percentage of cloud free pixels over that region in summer which enables a more robust determination of monthly mean LST. Adding a regression step for daily anomalies (using the predictor CC) yields the RKRK method and improves the preservation of spatial variability over the Iberian Peninsula. Moreover, a successive reduction of the station number (from 140 to 10 stations) reveals an increasing superiority of RKKLST and RKRK over RKK in both regions.
The application of a gridded observational dataset for climate monitoring or climate model validation requires knowledge of the uncertainties associated with the dataset. The estimation of the interpolation uncertainty, here the inter quartile range is the used uncertainty measure, is therefore an important issue within the frame of this thesis. By means of cross validation it is shown that the largest uncertainties occur in regions of low station density (e.g. Greenland), in mountainous regions and along coastlines (in these regions model evaluation results should be interpreted carefully). The magnitude of the interpolation error mainly depends on the station density, while the complexity of terrain has substantially less influence. On average over all regions and investigation days the target precision of the uncertainty estimate is reached. However, on local scales and for single days it can be clearly over- or underestimated. The application of satellite-derived predictors (LST and CC) yields no noteworthy improvement of the uncertainty estimate.
In the last study two regional climate simulations for Africa using the ERA-Interim driven COSMO-CLM (CCLM) model at two different horizontal resolutions (0.22° and 0.44°) are validated. It is assessed whether observed patterns and statistical properties of daily Tmin and Tmax are correctly represented in the model. The ERA-Interim reanalysis and a specially created observational dataset are used as reference. The observational dataset is generated by applying the RKRK algorithm (developed within the second study). The investigations show an occasionally large bias in Tmin and Tmax. The hemispheric summers are generally too warm and the temporal variability in temperature is too high, particularly over extra tropical Africa. The diurnal temperature range is overestimated by about 2°C in the northern subtropics but underestimated by about 2°C over large parts of the African tropics. CCLM reproduces the observed frequency distribution of daily Tmin and Tmax in all African climate regions, and the extreme values in the lower percentiles (5, 10, 20%) for Tmin are well simulated. The higher percentiles (80, 90, 95%) for Tmax are however overestimated by 2-5°C. For both Tmin and Tmax the 0.22° simulation is on average 0.5°C warmer than the 0.44° simulation. Additionally, the higher percentiles are about 1°C warmer for both Tmin and Tmax in the higher resolution run, while the lower percentiles in both runs match very well. Although the temperature pattern is represented in more detail along the coastlines and in topographically complex regions, the higher resolution simulation yields no qualitative improvement.
To summarize, the choice of the appropriate algorithm mainly depends on the interpolation conditions. In cases where the station density is high across the target region and the predictor space is adequately covered by observing stations, the computationally less demanding RK algorithm should be preferred. In regions where the station density is low the more robust RKRK algorithm should be the first choice. Due to the strong physical relation of both CC and LST to Tmin and Tmax the missing information is at least partially compensated for. The estimation of the interpolation uncertainty could be improved by applying a normal score transformation to the data prior to a kriging step. This is because the kriging assumption that the increments of the variable of interest are second order stationary can be approximately met by a normal score transformation.
The objective of the present doctoral thesis was to investigate the occurrence, distribution, and behaviour of six hydrophilic ethers: ethyl tert-butyl ether (ETBE), 1,4-dioxane, ethylene glycol dimethyl ether (monoglyme), diethylene glycol dimethyl ether (diglyme), triethylene glycol dimethyl ether (triglyme), and tetraethylene glycol dimethyl ether (tetraglyme) in surface-, waste-, ground- and drinking water samples. Solid phase extraction and gas chromatography/mass spectrometry were used to analyze the six hydrophilic ethers. Altogether more than 150 surface water samples, almost 100 of each groundwater and wastewater samples, and 10 raw and drinking water samples were analyzed during the research project.
Initially, the method was validated in order to simultaneously determine the analytes of interest in various aquatic environments. A solid phase extraction method that uses coconut charcoal (Resprep® activated coconut charcoal, Restek) or carbon molecular sieve material (SupelcleanTM Envi-CarbTM Plus, Supelco) for analyte absorption were found suitable for determination of ETBE, 1,4-dioxane, and glymes in surface-, drinking-, ground- and wastewater samples. Precision and accuracy of both methods was demonstrated for all analytes of interest. The recovery of target compounds from the ultrapure water spiked at 1.0 µg L−1 was between 86.8 % and 98.2 %, with relative standard deviation below 6 %. The samples spiked at 10.0 µg L−1 gave slightly higher recovery of 90.6 % to 112.2 % with a relative standard deviation below 3.4 % for each analyte. Detection and quantification limits in ultrapure water and surface waters were furthermore established. The limit of quantitation (LOQ) in ultrapure water ranged between 0.024 µg L−1 to 0.057 µg L−1 using Restek cartridges, and 0.030 µg L−1 to 0.069 µg L−1 using Supelco cartridges. In the surface water samples the calculated LOQ was 0.032 µg L−1 to 0.067µg L−1 using coconut charcoal material and 0.032 µg L−1 to 0.052 µg L−1 using the carbon molecular sieve material. Moreover, stability of the unpreserved and preserved water samples as well as the extracts was determined. Preservation of samples with sodium bisulfate (at 1 gram per Liter) resulted in much better stability of the ethers in water samples. Subsequently, 27 samples obtained from seven surface water bodies in Germany (Rivers Rhine, Lippe, Main, Oder, Rur, Schwarzbach and Wesel-Datteln Canal) were analyzed for the six hydrophilic ethers. ETBE was present in only two surface waters (Rhine River and Wesel-Datteln Canal) with concentrations close to the LOQ (up to 0.065 µg L−1). 1,4-Dioxane was detected in all of the water samples at concentrations reaching 1.93 µg L–1. Monoglyme was identified only in the Main and Rhine Rivers at the maximum concentration of 0.114 µg L–1 and 0.427 µg L–1, respectively. Very high concentrations (up to 1.73 µg L−1) of diglyme, triglyme, and tetraglyme were detected in the samples from the Oder River. These glymes were also detected in the Rhine River; however the concentrations did not exceed 0.200 µg L–1. Furthermore, tetraglyme was detected in the Main River at an average concentration of 0.409 µg L–1 (n = 6) and in one sample from the Rur River at 0.192 µg L–1.
Four sampling campaigns were conducted at the Oderbruch polder between October 2009 and May 2012, in order to study the behavior of the hydrophilic ethers and organophosphates during riverbank filtration and in the anoxic aquifer. Moreover the suitability of these target compounds was assessed for their use as groundwater organic tracers. At the time of each sampling campaign, concentrations of triglyme and tetraglyme in the Oder River were between 20–185 ng L–1 (n = 4) and 273¬–1576 ng L–1 (n = 4). Monoglyme, diglyme, and 1,4-dioxane were analyzed only during the two last sampling campaigns. At that time, the concentration of diglyme in Oder River was 65¬–94 ng L-1 (n = 2) and 1,4-dioxane 1610¬–3290 ng L–1 (n = 2). In the drainage ditch, following bank filtration, concentrations of ethers ranged between 1090 ng L–1 and 1467 ng L–1 for 1,4-dioxane, 23¬ng L–1 and 41 ng L–1 for diglyme, 37 ng L–1 and 149 ng L–1 for triglyme, and 496 ng L–1 and 1403 ng L–1 for tetraglyme. In the anoxic aquifer, 1,4-dioxane showed the greatest persistence during the groundwater passage. At the distance of 1150 m from the river and an estimated groundwater age of 41.9 years, a concentration above 200 ng L−1 was detected. A positive correlation was found for the inorganic tracer chloride (Cl−) with 1,4-dioxane and tetraglyme. Similarities in the behavior of Cl− and the organic compound suggested that 1,4-dioxane and tetraglyme are controlled by the same hydraulic process and therefore can be used as additional tracers to study the dynamics of the groundwater system. These results show that high concentrations of ethers are present in the surface water and are not removed during bank filtration processes. Moreover, the hydrophilic ethers persist in the anoxic aquifer and little or no degradation is expected, supporting, their possible application as organic tracers.
A separate sampling project was conducted for 1,4-dioxane that focused primarily on its fate in the aquatic environment. This study provided missing information on the extent of water pollution with 1,4-dioxane is Germany. Numerous waste-, surface-, ground- and drinking water samples were collected in order to determine the persistence of 1,4-dioxane in the aquatic environment. The occurrence of 1,4-dioxane was determined in wastewater samples from four municipal sewage treatment plants (STP). The influent and effluent samples were collected during weekly campaigns. The average influent concentrations in all four plants ranged from 262 ± 32 ng L−1 to 834 ± 480 ng L−1, whereas the average effluents concentrations were between 267 ± 35 ng L−1 and 62,260 ± 36,000 ng L−1. The source of increased 1,4-dioxane concentrations in one of the effluents was identified to originate from impurities in the methanol used in the postanoxic denitrification process. Spatial and temporal distribution of 1,4-dioxane in the river Main, Rhine, and Oder was also examined. Concentrations reaching 2,200 ng L−1 in the Oder River, and 860 ng L−1 in both Main and Rhine River were detected. The average load during the sampling was estimated to be 6.5 kg d−1 in the Main, 34.1 kg d−1 in the Oder, and 134.5 kg d−1 in the Rhine River. In all of the sampled rivers, concentrations of 1,4-dioxane increased with distance from the mouth of the river and were found to negatively correlate with the discharge of the river. In order to determine if 1,4-dioxane can reach drinking water supplies, samples from a Rhine River bank filtration site and potable water from two drinking water production facilities were analyzed for the presence of 1,4-dioxane in the raw water and finished potable water. The raw water (following bank filtration) contained 650 ng L−1 to 670 ng L−1 of 1,4-dioxane, whereas the concentration in the finished drinking water fell only to 600 ng L−1 and 490 ng L−1, respectively.
During the final project, investigations of the source identification of high glyme concentrations in the Oder River were carried out. During four sampling campaigns between January, 2012 and April, 2013, 50 samples from the Oder River in the Oderbruch region and Poland were collected. During the first two samplings in the Oderbruch polder, glymes were detected at concentration reaching 0.07 µg L-1 (diglyme), 0.54 µg L−1 (triglyme) and 1.73 µg L−1 (tetraglyme) in the Oder River. The extensive sampling campaign of the Oder River (about 500 km) in Poland helped to identify the area of possible glyme entry into the river. During that sampling the maximum concentrations of triglyme and tetraglyme were 0.46 µg L−1 and 2.21 µg L−1, respectively. A closer investigation of the identified area of pollution, helped to determine the possible sources of glymes in the Oder River. Hence, the final sampling focused on the Kaczawa River, a left tributary of the Oder River and Czarna Woda, a left tributary of Kaczawa River. Moreover, samples from an industrial wastewater treatment plant were collected. Samples from Czarna Woda stream and Kaczawa River contained even higher concentrations of diglyme, triglyme, and tetraglyme, reaching 5.18 µg L−1, 12.87 µg L−1 and 80.81 µg L−1, respectively. Finally, three water samples from a wastewater treatment plant receiving influents from a copper smelter were analyzed. Diglyme, triglyme, and tetraglyme were present at an average concentration of 569 µg L−1, 4300 µg L−1, and 65900 µg L−1, respectively in the wastewater. Further research helped to identify the source of the glymes in the wastewater. The gas desulfurization process – Solinox implemented in the nearby copper smelter uses glymes as physical absorption medium for sulfur dioxide.
Results of this doctoral research provide important information about the occurrence, distribution, and behavior of hydrophilic ethers: 1,4-dioxane, monoglyme, diglyme, triglyme, and tetraglyme in the aquatic environment. A method capable of analyzing a wide range of ether compounds: from a volatile ETBE to a high molecular weight tetraglyme was validated. 1,4-Dioxane and tetraglyme were found to be applicable as organic tracers, since they are not easily attenuated during bank filtration and the anoxic groundwater passage. The extent of water pollution with 1,4-dioxane was shown in waste-, surface-, ground-, and drinking waters. One source of extremely high concentrations of 1,4-dioxane in a municipal sewage treatment plant applying postanoxic denitrification was identified, however more information is needed on the entry of 1,4-dioxane into surface waters. Moreover, 1,4-dioxane was present in drinking water samples from river bank filtration, which demonstrates its persistence in the aquatic environment and its low degradation potential during bank filtration and subsequent water treatment. Furthermore, this was the first study that focused primarily on identifying sources of glymes in surface waters. Glymes find a widespread use in industrial sectors, hence establishing their origin in the surface water is difficult (as with 1,4-dioxane). In this work, a gas desulphurization process was identified to be a dominating source of glyme pollution in the Oder River.
This thesis aims to analyse in a first step the physical and chemical properties of soil profiles along pedomorphological transects in different land used conditions (protected, partly protected as well as cultivated and pastured areas) in North West Benin and in South East Burkina Faso. The information about soils, which are carried out in consideration of the pedogenesis processes like weathering types, saprolitisation, formation of laterite crusts and denudation within the planation surfaces are therefore correlated in a second step with the structure and dynamic of woody plant around individual soil profiles. The relationship soil properties and woody plant is investigated in order to assess the reciprocal influence between the diversity of woody plants and soil characteristics within a small scale study and under different land use conditions.
A common vertical and lateral differentiation of physical and chemical properties regardless of the partly protected, protected and cultivated status of the sites can be noticed. Thus, in the cultivated site of Kikideni and in the partly protected zone of Natiabouani (South East Burkina Faso) sandy loam and sandy clay loam soil surfaces are widespread because of the occurrence of similar erosion processes like sheet wash, rill and gully erosion while in the central part of the Pendjari National Park loamy soil textures are prevailing. In fact, the steepness of the relief and the length of the slopes in the Pendjari Park seem to limit the development of some erosion forms as gully. Furthermore, the classification of soils reflects the variation of pedological processes along the transects and thus the occurrence of different soil types. The status of the sites may play an insignificant role in the differentiation of soil properties within the scale of small pedomorphological transects. A direct comparison of the vegetation type in the land use respectively partly protected and in the total protected sites (National Park of Pendjari) reveals a transition from the shrub savanna to the tree savanna. In conclusion it is important to insist on the fact that the variations of soil parameters within small slopes and the different sites are more conditioned by varying erosion processes and drainage conditions than the status protected or land use sites while the composition and diversity of plants is influenced by the status of the sites, the prevailing management tools, the pedogenetic conditions as well as the presence of wild animals like elephants. The ordination diagram shows that the organic matter is better correlated to the subgroup representing principally the sites of the hunting zone of the Pendjari Park and might be an explaining factor to the distribution of these sample sites groups. CEC ratios in the partly protected site of Natiabouani represent the highest measured in all sites. Nevertheless, statistical analysis of the CCA (canonical correspondence analysis) indicates generally a low correlation. This tendency is consolidated by the Monte Carlo test (p=0.14) which is a good indicator of species and environmental conditions. The detailed analysis of soil properties and the vegetation dynamic as well as their relationship within small pedomorphological transects represent an important pedological and botanical data collection involving different compartments. This thesis contributes to the better understanding of the savanna landscapes of West Africa and may provide essential scientific background for each development project directed towards interdisciplinary and integrative researches.
In dieser Arbeit wird die Richtungsabhängigkeit seismischer Geschwindigkeiten im Erdmantel unterhalb Deutschlands und angrenzender Gebiete durch die Analyse der teleseismischen Kernphase SKS auf Doppelbrechung untersucht (Scherwellen-Splitting). Die Anisotropie wird durch die Splittingparameter Φ und δt beschrieben und erlaubt Rückschlüsse auf geodynamische Prozesse.
Untersucht werden Aufzeichnungen des Deutschen Seismologischen Regionalnetzes (GRSN) und assoziierter Stationen aus dem Zeitraum von 1993 bis 2009. Für drei Stationen des Gräfenberg-Arrays (GRF-Array) sind Wellenformen ab 1976 verfügbar, welche damit einen weltweit einmaligen Datensatz liefern.
Auf Grund des stetigen Ausbaus der seismologischen Netze und des langen Beobachtungszeitraumes können über 3.000 Seismogramme ausgewertet werden. Der Hauptteil dieser Arbeit besteht daher in der Entwicklung einer automatischen Methodik zur Analyse von SKS-Splitting: ADORE ("Automatische Bestimmung von DOppelbrechnungsparametern in REgionalseismischen Netzwerken"). Für regionale Netze wie das GRSN gewährleistet ADORE eine objektive Bestimmung der Splittingparameter. Zunächst wird das seismologische Netzwerk als seismisches Array aufgefasst, um durch eine Frequenz-Wellenzahl-Analyse den Einsatz der SKS-Phase ohne manuellen Eingriff zu bestimmen. Die Berechnung der Splittingparameter erfolgt durch eine Inversion nach der Methode der Minimierung des transversalen Energieanteils. Automatisch wird das optimale Fenster um den SKS-Einsatz positioniert, für jede Beben-Stations-Kombination werden dazu 3.600 Einzelinversionen durchgeführt.
Um diese Vielzahl von Auswertungen in akzeptabler Zeit zu berechnen, nutzt ADORE moderne Rechnerarchitekturen aus, verteilt die Berechnungen auf mehrere Computer im lokalen Netzwerk und erzielt damit eine Beschleunigung um einen Faktor 60.
Die Analyse des gesamten Datensatzes ergibt folgende Ergebnisse: An allen analysierten Stationen wurde ein Scherwellen-Splitting festgestellt, der Stationsuntergrund weist somit überall Anisotropie auf. Für 240 Erdbeben können insgesamt 494 Wertepaare mit höchster Qualität bestimmt werden.
Unter der Annahme einer homogenen ungeneigten anisotropen Schicht unterhalb der jeweiligen Station können die Einzelmessungen pro Station gemittelt werden. Damit sind Regionen mit ähnlichen Merkmalen gut zu identifizieren: Im Norden Deutschlands herrschen NW-SO-, in der Mitte W-O-Richtungen und im Süden SW-NO-Richtungen vor.
Die Verzögerungszeiten liegen im Bereich zwischen 1.0 (Station Taunus) und 2.2 Sekunden (Tannenbergsthal, TANN). Auf Grund des hohen Wertes sind die Ursachen für die hier beobachteten Zeiten dem Erdmantel und nicht der Kruste zuzuordnen. Die bevorzugte Ausrichtung von anisotropen Kristallen auf Grund von Fließprozessen von Mantelmaterial ist Quelle der beobachteten Anisotropie. Rezente Fließprozesse von Mantelmaterial sind vor allem an der Unterkante der Lithosphäre wahrscheinlich. Durch Gebirgsbildungsprozesse, vorhandene Gebirgswurzeln oder regionale Veränderungen in der Mächtigkeit der Lithosphäre entstehen Barrieren für viskoses Mantelmaterial.
Als tektonische Ursachen für die hier gemessenen Orientierungen ist im Norden die Tornquist-Teisseyre-Linie (TTZ), in der Mitte die Variszische Gebirgsbildung und im Süden Einflüsse des Alpenbogens anzusehen. Ausnahmen bilden die Stationen Clausthal-Zellerfeld (CLZ), Rügen und Black-Forest-Observatory (BFO). Während bei letzterer ein Einfluss der Spreizungszone des Oberrheingrabens zu vermuten ist, scheint die Intrusion des Brockengranits die Beobachtungen an CLZ zu prägen. Rügen liegt in einer Übergangszone zwischen Sorgenfrei-Tornquist-Zone und TTZ.
Durch die Vielzahl von vorhandenen Einzelmessungen lassen sich an manchen Stationen komplexe Modelle untersuchen. Dazu zählen neben Gradientmodellen auch die geneigte Schicht und Zwei-Schicht-Modelle. Für sechs Stationen kann ein Zwei-Schicht-Modell erstellt werden: BFO, Gräfenberg A1, Fürstenfeldbruck (FUR), Rüdersdorf (RUE), TANN und Unterbreitzbach (UBBA). Die Interpretation der Richtungen von oberer und unterer Schicht gelingt für einen Teil der genannten Stationen: An BFO liegt die Orientierung der unteren Schicht parallel zur Vorzugsrichtung der variszischen Gebirgsbildung, jene der obere Schicht antiparallel zur Spreizungsrichtung des Rheingrabens. Für die Station FUR ist eine Überlagerung mit der Streichrichtung des Alpenmassivs zu beobachten. An GRA1 wird die untere Schicht offenbar durch rezente oder eingefrorene Anisotropie des Böhmischen Massivs bzw. des Eger-Riftsystems beeinflusst. Eine vergleichbare Wirkung ist durch die TTZ an der Station RUE zu erkennen.
ADORE wurde weiterhin auf einen Datensatz des temporären RIFTLINK-Projektes angewandt.
Forty two samples of the Late Eocene Kiliran oil shale, Central Sumatra Basin, Indonesia were collected from a 102 m long drill core. Palynofacies and geochemical analyses have been carried out to reconstruct the paleoenvironmental conditions and paleoecology during deposition of the oil shale. Amorphous organic matter (AOM) is very abundant (>76%). B. braunii palynomorph is present (3-16%) as the only autochtonous structured organic matter and generally more abundant in middle part of the profile. The stable carbon isotopic composition of organic matter (δ13C) varies from -27.0 to -30.5‰ and is generally more depleted in middle part of the profile. The ratio of total organic carbon to sulfur (TOC/S), used as salinity indicator, ranges from 2.5 to 15.8 and shows variations along the profile. Relatively less saline environments are observed in the middle part profile. Fungal remains are generally present only in middle part of the profile with distinct peak of abundances. The presence of fungal remains is regarded as an indication for a relatively warmer climate during deposition of middle part of the profile. The warmer climate is thought to influence the establishment of a thermocline, limiting the supply of recycled nutrients to the epilimnion. Consequently, the primary productivity in the Kiliran lake decreased during deposition of the middle part of the profile as indicated by the relatively depleted δ13C and the blooming of B. braunii. The chemocline was also shoaling during deposition of the middle part of the profile according to the higher abundance of isorenieratene derivatives of green sulfur bacteria origin. The warmer climate affected also to increase of water supply and thus less saline environments.
Tectonic subsidence is also thought to be a significant factor for the development of the Kiliran lake. The Zr/Rb ratio, an indicator for grain size, ranges from 0.4 to 1.3 and generally increases upwards along the profile. Three sudden decreases of the ratio are observed, indicating rapid change to finer grain size. These decreases are interpreted to indicate rapid deepening events of the lake due to mainly periodic subsidence. During deposition of lower part of the profile, the subsidence rates might have been relatively higher than sediment and water supply rates, resulting in a higher autochtonous fraction in the oil shale. During deposition of middle part of the profile, the sediment and water supply rates were relatively higher promoting distinct progradational sedimentation. Subsequently, the lake became more shallow and smaller during deposition of the upper part of the profile, leading to a relatively higher terrigenous input to the oil shale.
Norneohop-13(18)-ene and neohop-13(18)-ene derived from methanotrophic bacteria are the dominant hopanoid hydrocarbons. The sum of their concentrations varies from 40.6 to 360.0 μg/g TOC. The δ13C of these compounds are extremely depleted (-45.2 to -50.2‰). The occurrence of abundant bacteria including methanotrophic bacteria was responsible for the recycling of carbon below the chemocline of the lake. The effect of the recycling of carbon is observed by the presence of a concomitant depletion (about 7-9‰) in 13C of some specific biomarkers derived from organisms dwelling in the whole phototrophic zone.
4-Methylsterane and 4-methyldiasterene homologues occur in the oil shale as the predominant biomarkers. The sum of the concentrations of all homologues are about 40.3-1,009.2 μg/g TOC with generally higher values in uppermost and lower parts of the profile. Ca accounts as the predominant element in the oil shale, ranging from 5.0 to 16.7%. This element shows generally parallel variation with the 4-methylsterane homologues along the profile. This suggests that the 4-methylsteranes were derived from biological sources favoring more alkaline and more trophic environments. On the other hand, these compounds were less abundant in middle part of the profile which is consistent with less alkaline and less trophic environments promoting B. braunii to bloom.
The 4-methylsterane homologues are considered to originate from Dinoflagellates. Alternation between Dinoflagellates and B. braunii in Paleogene lake systems due to water chemistry changes are known from previous studies. Moreover, freshwater Dinoflagellates have been frequently reported to occur in the basin depocenters. In the present case, distinct alternation between B. braunii abundances and concentrations of 4-methylsterane homologues along the studied oil shale profile suggest that the 4-methylsterane homologues were derived from freshwater Dinoflagellates although dinosterane is not present in the sediment extracts. Water alkalinity and trophic level changes were most likely responsible for the alternation of Dinoflagellates and B. braunii blooming.
The mantle xenoliths collected by kimberlites indicate that the subcratonic mantle underneath the Archean crust is mostly a residue of high degrees of partial melting which was subsequently reenriched. The majority of the xenoliths show cryptic metasomatism and only few modal metasomatism.
Much effort has been put into deciphering different kinds of enrichment processes within the mantle. Here, we take the approach to look into the inventory of subcalcic garnets which stem from cpx-free harzburgites and dunites. These subcalcic garnets, commonly with sinusoidal REE patterns, carry the major budget of the trace elements of their host rock. Thus, they are promising objects to study both depletion and enrichment. Most importantly, the analysis of a single grain subcalcic garnetwill provide almost all important information of the bulk rock. Our aim is to gain detailed information mainly on metasomatism on a craton wide scale by combining major, trace elements and Lu-Hf and Sm-Nd isotopic signatures from subcalcic garnets. Eventually, we will summarize the metasomatic agent(s) and processes and possibly the timing of the enrichment within the lithospheric mantle underneath the Kaapvaal craton.
This research was conducted in the Rwenzori Region of the Western Branch, East African Rift System (EARS). The EARS is a tectonic structure extending over a length of more than 3000 km from the Afar Triple Junction, in Ethiopia, to Lake Malawi in the south. The Western Rift System is a roughly NE to ENE trending sector of the EARS, which runs along the western boundary of Uganda and the neighboring Democratic Republic of Congo (D.R.C). It stretches 2100 km from Nimule, NW on Uganda-Sudan border, extending to Lake Malawi in the SE of Africa. The unusual uplift of the Rwenzori Mountains within an extensional regime and the mechanisms associated with the high frequency of seismic activity in the region was hardly understood and therefore, had remained a subject of contention that needed to be critically addressed in detail. To my knowledge, this was probably the first study to be performed and documented in great depth within the domains of seismic noise variation, seismic anisotropy and b value analyses beneath the Rwenzori Region. After about six years of operation (2006-2012), the seismology group of the RIFTLINK Research Project (www.riftlink.org) acquired a vast amount of high-quality, digital data that were collected using a seismic network of well calibrated seismic equipment. The project was divided into two phases. Phase I, that operated between February 2006 - September 2007, consisted of thirty-two temporary seismic stations, which were selectively spread out in the Rwenzori Region on the Ugandan side, to detect and record extremely weak as well as strong naturally occurring earthquakes. The seismic equipment used included EDL and REFTEK digitizers, which were coupled with Güralp and MARK sensors respectively (REFTEKS: only short-period MARK sensors, EDLs: short-period MARK plus few broadband Güralp Sensors). Exactly 22375 earthquakes were recorded. The data were processed using the SEISAN software package. About 14413 earthquakes were carefully localized using the velocity model of Bram (1975) that implements a Vp=Vs ratio fixed at 1.74. Phase II, that extended between 2009-2012 consisted of thirty-two seismic stations, which were spread out around the Rwenzori Mountains, both on the Ugandan side and the neighboring D.R.C. Only Taurus digitizers that were coupled with Trillium sensors were used in the D.R.C. On the Ugandan side however, both EDL and Taurus digitizers, which were coupled with Trillium and Güralp sensors were used. ...
Die vorliegende Arbeit wurde im Rahmen des Forschungsprojekts „Integrierte Analyse von mobilen, organischen Fremdstoffen in Fließgewässern“ (INTAFERE) am Institut für Physische Geographie an der Goethe-Universität Frankfurt erstellt. In INTAFERE wurde das Gefährdungspotenzial von mobilen, organischen Fremdstoffen (MOF) für aquatische Ökosysteme und die natürlichen Wasserressourcen in integrierter und partizipativer Art und Weise untersucht. MOF sind chemische Substanzen, die in Alltagsprodukten enthalten sind und durch unterschiedliche Eintragsfade in unbekannten Mengen in Oberflächengewässer eingetragen werden. Problematisch sind aus Umweltgesichtspunkten ihre Eigenschaften: sie besitzen im Wasser eine hohe Mobilität und sind schwer abbaubar. Dies führt zu einer Persistenz über lange Zeiträume. Für einige dieser Substanzen wurde zudem gezeigt, dass sie in sehr geringen Konzentrationen biologisch aktiv sind und für aquatische Ökosysteme eine Gefahr darstellen. In INTAFERE wurden drei zentrale Ziele verfolgt: Charakterisierung des Problemfeldes MOF, Erzeugung von praxisrelevantem Wissen für das Management von MOF und Entwicklung einer Softwareanwendung, die gesellschaftliche Aushandlungsprozesse durch eine transparente Darstellung der Wirkungszusammenhänge im Problemfeld unterstützt. Um einen Beitrag für die Erfüllung der Ziele zu leisten, war es die Aufgabe der Verfasserin, eine Akteursanalyse und -modellierung durchzuführen sowie Zukunftsszenarien im Bereich der MOF zu entwickeln. Dafür existierte keine adäquate Methodik, daher verfolgt die Dissertation zum einen die Entwicklung einer Methodik und zum anderen deren Anwendung im Kontext des Projektes INTAFERE. Da im Forschungsprozess die Durchführung von Analysen, die wissenschaftliche und gesellschaftliche Sichtweise der Problematik sowie die Erarbeitung von praktischen Lösungen im Mittelpunkt standen, wurde eine transdisziplinäre Herangehensweise gewählt. Ziel war es, eine Methodik zu entwerfen, die sowohl eine Entwicklung von Szenarien als auch eine Modellierung von Handlungsentscheidungen umfasst. Eine Modellierung und Visualisierung von Handlungsentscheidungen ist notwendig, um Strategien für ein Umweltproblem für verschiedene Szenarien zu ermitteln, und damit einen Lernprozess der Stakeholder zu initiieren. Dies wurde mit der transdisziplinären Methode „Akteursbasierte Modellierung“ umgesetzt. Hierbei wurden insbesondere Aspekte der Problemwahrnehmung von Akteuren und deren Darstellung, der partizipativen Szenarienentwicklung sowie der semi-quantitativen Modellierung von Handlungsentscheidungen berücksichtigt. Die Verfasserin hat mit der semi-quantitativen akteursbasierten Modellierung eine Methode erarbeitet und getestet, die bisher unverbundene Komponenten (wie die Software Dynamic Actor Network Analysis (DANA) und die Szenarienentwicklung) zusammenführt. Um Handlungsentscheidungen unter verschiedenen Szenarien zu modellieren hat die Autorin eine sequentielle Modellierung entwickelt, die mit der Software DANA durchgeführt werden kann. Die dafür notwendige Weiterentwicklung von DANA wurde von Dr. Pieter Bots (TU Delft) umgesetzt. Die akteursbasierte Modellierung läuft in drei methodischen Schritten ab: 1. Modellierung von Akteurs-Sichtweisen in Form von Wahrnehmungsgraphen und deren Analyse, aufbauend auf Ergebnissen von qualitativen, leitfaden-gestützten Expertengesprächen (= Akteursmodellierung), 2. partizipative Szenarienentwicklung mit den Akteuren und 3. Zusammenführung der Ergebnisse der Akteursmodellierung und der Szenarienentwicklung und darauf aufbauend eine sequentielle Modellierung von Handlungsentscheidungen und deren Auswirkungen auf Schlüsselfaktoren. Im Zuge der Anwendung auf das Problemfeld der MOF wurde für folgende Akteure jeweils ein Wahrnehmungsgraph modelliert: Obere Wasserbehörde, Umweltbundesamt, Umwelt- und Verbraucherschutzorganisationen, Wasserversorger sowie für die Hersteller von verschiedenen MOF, weiterhin für die European Flame Retardants Association und die Weiterverarbeitende Industrie. Das Ergebnis der Szenarienentwicklung waren vier Szenarien: ein Gesundheitsszenario, unter der Annahme von hohen lokalen Umweltstandards durch nachhaltigkeitsorientierte KonsumentInnen, ein Umweltszenario, in dem eine starke Regulierung und nachhaltigkeitsorientierter Konsum Hand in Hand gehen, ein Globalisierungsszenario, in dem Wirtschaftsmacht und preisbewusste KonsumentInnen statt staatliche Regulierung vorherrschen und ein Technikszenario, unter der Annahme, dass Kläranlagen, bedingt durch eine starke Regulierung, aufgerüstet werden. Bei der Modellierung von Handlungsentscheidungen wurden die Wahrnehmungsgraphen und die vier Szenarien miteinander verknüpft. Pro Substanz wurde ein Modell entwickelt, welches die wichtigsten Systemkomponenten in einer angemessenen Komplexität umfasst und die von den Akteuren gemeinsam getragene Einschätzung der Wirkungsbeziehungen darstellt. Insgesamt wurden 16 Modelle entwickelt. Basierend auf den simulierten Akteurshandlungen wurden relativen Veränderungen der Schlüsselfaktoren Produktion, Import und Leistungsfähigkeit der Kläranlagen für die vier genannten Szenarien berechnet. In Zusammenarbeit mit Pieter Bots konnten algorithmische Beiträge zur Analyse- und Modellierungssoftware DANA getestet und verbessert werden. Da keine vollständige und zugleich leicht verständliche Einführung zu DANA vorlag, wurde für Nutzer im Rahmen dieser Dissertation eine Anleitung verfasst, die die Modellierung von Wahrnehmungsgraphen und deren Analyse sowie alle Schritte der akteursbasierten Modellierung mit DANA erläutert.
In dieser Arbeit werden Schmelz- und Anreicherungsprozesse des Erdmantels, sowie Kristallisationsereignisse der Erdkruste zweier ausgewählter Gebiete in Namibia und Spanien mithilfe geochemischer Methoden rekonstruiert und in einen zeitlichen Zusammenhang gebracht. Ein Vergleich der gewonnenen Ergebnisse beider Kompartimente soll dabei weitere Informationen liefern inwieweit Prozesse des Erdmantels und der Erdkruste miteinander verknüpft waren. Insbesondere soll ein weitere Beitrag zur aktuellen Diskussion geliefert werden, bei der sich das sogenannte „pulsed growth“ und „steady accumulation“ Modell gegenüberstehen (siehe Zusammenstellung Pearson et al., 2007). Zudem tragen die neu gewonnenen Daten dazu bei, die regionalen geologischen Gegebenheiten im besonderen Hinblick auf die geotektonische Geschichte besser zu verstehen.
Das Gibeon Kimberlit Feld befindet sich in der tektonischen Einheit des Rehoboth Terranes in Namibia und ist gekennzeichnet von Vulkanismus vor etwa 72.5 Ma (Davies et al., 2001), der Granat Peridotite und krustale Xenolithe mit an die Oberfläche beförderte. Eine klare Einordnung des Rehoboth Terranes in die Gesamtheit des Süd Afrikanischen Plattenverbunds ist noch nicht vollständig geklärt.
Die Südöstliche vulkanische Provinz in Spanien (SEVP) mit besonderem Hinblick auf die Region um Casas de Tallante stellt das zweite Probengebiet für diese Arbeit dar. Vor etwa 2.6 Ma (Bellon et al., 1983) kam es zur Extrusion von alkali-basaltischen Schmelzen, die zahlreiche Spinell / Plagioklas Peridotite mit sich brachten. Tufflagen, sowie die Matrix der Basalte ermöglichen einen Einblick in die untere Kruste der Region.
Untersuchungen der Erdmantelproben aus Namibia auf ihre Haupt- und Spurenelementchemie, sowie Lu-Hf und Sm-Nd Isotopie zeigten, dass zwei verschiedene Manteltypen vorliegen („N“ und „σ“ Typ), die zu einem Zeitpunkt um etwa 850 Ma („N“) und 1.9 Ga („σ“) angereichert wurden. Eine letzte Anreicherung beider Typen fand vermutlich während der Pan–Afrikanischen Orogenese um etwa 450 Ma statt. Die Reinterpretation eines zuvor publizierten Datensatzes (Pearson et al., 2004), suggeriert, dass es zu einer ersten Verarmung der σ Peridotite um etwa 2.9 Ga kam.
Untersuchungen der U-Pb und Hf Isotopie an Zirkonen aus der unteren Kruste des Probengebiets in Namibia ergaben, dass es zur Bildung von juvenilem Krustenmaterial vermutlich bereits im Archaikum kam (wie bereits vorgeschlagen durch z.B. Hoal et al., 1995; Franz et al., 1996), sowie in den Zeiträumen von 2.3 bis 2.7 und 1.5 bis 1.6 Ga, mit jeweils anschließendem krustalem Recycling und Krustenmischung. Eine Übereinstimmung von Mantel- und Krustenevents konnte für die Zeiträume von etwa 1.8, 0.8 - 0.9 Ga und 0.4 – 0.5 Ga gefunden werden. Eine mögliche erste Verarmung des σ Mantels wird bestätigt durch Zirkonalter im Bereich von 2.7 bis 2.9 Ga.
Die Analyse ausgewählter Spinell / Plagioklas Peridotite aus der SEVP, ergaben, dass ein heterogener Mantel mit mindestens 3 verschiedenen Typen vorliegt. Eine Korrelation der Lu-Hf Isotopie von 3 Proben dieses Probensatzes, sowie den Hf Isotopien einer weiteren Probe von Bianchini et al. (2011) suggerieren, dass es eventuell zu einem Verarmungsereignis zu einem Zeitpunkt von etwa 550 Ma kam. Sr Isotopien von Klinopyroxenen und Plagioklasen im Vergleich ergaben, dass die Sr Isotopie der Plagioklase, im Gegensatz zu den Klinopyroxenen, von denen der Alkali Basalte überprägt wurden.
Zirkonanalysen aus Lokalitäten innerhalb der SEVP (U-Pb, Hf) ergaben ein weitreichendes Altersspektrum, beginnend bei etwa 2-3 Ma bis hin ins Archaikum (2.7 bis 2.9 Ga) mit Provenance Ursprung aus Gondwana und dem Arabisch-Nubischen Schild. Die Kombination der U-Pb Altersinformationen mit den entsprechenden Hf Isotopien, zeigten, dass es vermutlich bereits im Archaikum zu juveniler Krustenbildung kam. Zirkone > 100 µm datieren den Zeitpunkt der Eruption der Alkali Basalte mit Altern um etwa 2.6 Ma und Hf Isotopien, die einem leicht verarmten Mantel entsprechen. Ein mögliches Verarmungsereignis im Erdmantel zu einem Zeitpunkt von etwa 550 Ma, ist im Einklang mit Krustenrecycling zu selbigem Zeitpunkt.
Die neugewonnenen Daten dieser Arbeit unterstützten das „pulsed growth“ Modell.
Literatur
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Die Wechselwirkung zwischen zwei verschiedenartigen Wellenphänomenen in einer Höhe von ca. 10 bis 100 km, der mittleren Atmosphäre, ist das zentrale Thema der vorliegenden Arbeit. Schwerewellen entstehen durch Oszillationen der Luft in einer stabil geschichteten Atmosphäre. Durch die Vielzahl von Schwerewellen-Paketen, die in der Troposphäre durch Gebirge, Gewitter, Fronten und andere dynamische Prozesse angeregt werden, wird Energie und Impuls in die mittleren Atmosphäre transportiert. Durch den turbulenten Zerfall von brechenden Schwerewellen wird auf die mittlere Strömung eine Kraft ausgeübt, welche im Bereich der Mesopause bei ca. 90 km maximal wird. Daraus resultiert die sogenannte interhemispherische residuelle Zirkulation, die in der Mesosphäre den Sommer- mit dem Winterpol verbindet und die beeindruckend kalte Sommer-Mesopause mit Temperaturen von unter −140°C verursacht. Thermische Gezeiten sind ein weiterer wichtiger Teil in der Dynamik der mittleren Atmosphäre. Sie werden durch die Erwärmung der Tagseite der Erde angeregt und sind globale Schwingungen mit Perioden von 24 Stunden und harmonischen Vielfachen. Mit Wind- und Temperatur-Amplituden von bis zu 50 m/s und 30 K dominieren sie die Tagesvariabilität im Mesopausen-Bereich.
In der Mesosphäre wird die Wechselwirkung zwischen Schwerewellen und thermischen Gezeiten wichtig. Dort wird durch die Gezeitenwinde das Brechen von Schwerewellen zeitlich moduliert und eine periodische Kraft erzeugt, welche auf die Gezeiten rückwirkt. Doch selbst unter Zuhilfenahme modernster Hochleistungsrechner kann in komplexen Zirkulationsmodellen nur ein Bruchteil des turbulenten sowie des Wellen-Spektrums aufgelöst werden. Der Effekt der nichtaufgelösten Skalen, wie Turbulenz und Schwerewellen, muss somit in effizienter Weise parametrisiert werden. Üblicherweise wird in Schwerewellen-Parametrisierungen die horizontale und zeitliche Variation des Hintergrundmediums vernachlässigt. Es entsteht eine vertikale Säule, in der sich stationäre Schwerewellen-Züge instantan nach oben ausbreiten. Es ist jedoch äußerst fraglich, inwieweit eine solche Beschreibung, auf der ein Großteil früherer Untersuchungen basiert, für das Ergründen der Schwerewellen-Gezeiten-Wechselwirkung hinreicht. Für diese Arbeit wurde deswegen das Ziel gesetzt, die Defizite der konventionellen Beschreibung der Schwerewellen-Ausbreitung in realistischen Gezeiten zu quantifizieren.
Die "Ray Tracing"-Methode wird auf die Problemstellung der Schwerewellen-Gezeiten-Wechselwirkung angewendet. In der "Ray Tracing"-Methode werden Schwerewellen-Pakete entlang ihrer Ausbreitungspfade explizit verfolgt und Veränderungen der Schwerewellen-Eigenschaften durch den Einfluss der Hintergrundströmung berücksichtigt. Vom Autor wurde das globale "Ray Tracing"-Modell RAPAGI (RAy PArameterization of Gravity-wave Impacts) entwickelt und mit realistischen Gezeitenfeldern aus dem Zirkulationsmodell HAMMONIA (HAmburg MOdel of the Neutral and Ionized Atmosphere) betrieben. In verschiedenen "Ray Tracing"-Experimenten wird für ein einfaches Schwerewellen-Ensemble gezeigt, wie horizontale Gradienten des Hintergrundmediums sowie dessen Zeitabhängigkeit wesentlichen Einfluss auf die Ausbreitung und Dissipation von Schwerewellen nehmen. Zum einen führt die durch Gezeitenwellen hervorgerufene Transienz zu einer tageszeitlichen Modulation der absoluten Schwerewellen-Frequenz.
Die dadurch induzierten Variationen der horizontalen Phasengeschwindigkeit der Schwerewellen können die anfängliche Phasengeschwindigkeit um bis zu eine Größenordnung übertreffen und folgen dem Verlauf des Hintergrundwindes. Die kritische Filterung von Schwerewellen wird durch diese Modulation abgeschwächt, was im Vergleich zu konventionellen Schwerewellen-Parametrisierungen zu einer im Mittel um 30 % geringeren Kraftwirkung auf die Gezeiten führt. Zum anderen werden durch horizontale Gradienten in der gesamten Hintergrundströmung Schwerewellen-Pakete horizontal abgelenkt. Wellen, die gegen die Hintergrundströmung laufen, werden in der Stratosphäre in die Maxima der Wind-Jets hineingeführt. Durch dieses Verhalten wird analog zum Fermatschen Prinzip der geometrischen Optik die Laufzeit der Schwerewellen in der mittleren Atmosphäre minimiert. Es entsteht eine Fokussierung von Schwerewellen-Feldern, bei gleichzeitiger Zunahme der horizontalen Wellenzahl in den Experimenten im Mittel um ca. 10 %. Dadurch reduziert sich der Schwerewellen-Impulsfluss und die mittlere und ebenfalls die periodische Kraft auf die Hintergrundströmung im Mittel um weitere 20 % bis 30 %. Konventionelle Schwerewellen-Parametrisierungen scheinen somit die Kraftwirkung von brechenden Schwerewellen zu uberschätzen. Aus den Ergebnissen der Arbeit wird klar, dass Schwerewellen-Parametrisierungen nicht "blind" für jede Untersuchung genutzt werden können. Alle Annahmen und Näherungen in Parametrisierungen müssen je nach Zielstellung neu getestet werden.
Occurrence and sources of 2,4,7,9-tetramethyl-5-decyne-4,7-diol (TMDD) in the aquatic environment
(2011)
The aim of the present study was to identify the sources of 2,4,7,9-tetramethyl-5-decyne-4,7-diol (TMDD) into the aquatic environment and to investigate its occurrence in rivers and wastewater treatment plants (WWTPs). Therefore, TMDD was analyzed in 441 wastewater samples from influents and effluents of 27 municipal WWTPs, in 6 sludge samples, in 52 wastewater samples from 3 sewage systems of municipal WWTPs, in 489 surface samples from 24 rivers, in 9 wastewater samples of 3 paper-recycling industries and in 65 groundwater samples. TMDD was also analyzed in household paper products, in 23 samples of toilet
papers, in 5 types of paper towels and in 12 types of paper tissues. The samples were collected between 2007 and 2011. The water samples were extracted with solid phase extraction (SPE) and the household paper samples with Soxhlet extraction. Gas chromatography-mass spectrometry (GC-MS) was used for quantification purposes. Between November 2007 and January 2008, TMDD was detected in the river Rhine at Worms with permanent high concentrations (up to 1330 ng/L). The results showed that TMDD is uniformly distributed across the river at Worms. An increase of the mean TMDD concentration from approximately 500 ng/L to 1000 ng/L was registered in January 2008. Due to the minor fluctuations of the TMDD concentration during the sampling period it is expected that the input of TMDD into the river is continuous. Therefore, TMDD might rather originate from effluents of municipal WWTPs than from temporal sources. The mean TMDD load based on the analysis of 147 water samples collected in the River Rhine was 62.8 kg/d which is equivalent to 23 t/a suggesting that TMDD must be used and/or produced in high quantities in order to be found in those high concentrations. To determine if TMDD is discharged by effluents of municipal WWTPs into the rivers, 24 hours influent and effluent samples of four municipal WWTPs in the Frankfurt/Rhine-Main metropolitan region were collected during November 2008 and February 2010 and analyzed for TMDD. The TMDD influent concentrations varied between 134 ng/L and 5846 ng/L and the effluent concentrations between <LOQ (limit of quantitation) and 3539 ng/L. The TMDD elimination rates in the four WWTPs varied between 33% and 68%. The results showed that effluents of municipal WWTPs are an important source of TMDD in the aquatic environment because TMDD is not completely removed from the sewage during the wastewater treatment. Weekly and daily variations of the TMDD concentration in the influents of two municipal WWTPs indicated that both private households and indirect industrial dischargers contribute to the introduction of TMDD into the municipal sewage systems. A more detailed study of the TMDD elimination rate in the different wastewater treatment stages was carried out in the WWTP Niederrad/Griesheim in Frankfurt am Main. The results showed that the removal of TMDD is mainly carried out during the aerobic biological treatments, where the elimination rate was 46%. In contrast, during the anoxic treatment the removal efficiency was only 1.4% and during the mechanical treatment the elimination rate was 19%. To determine the sources of TMDD in the sewage, household paper products (paper tissues, toilet papers and paper towels) were analyzed for TMDD using Soxhlet extraction. TMDD was detected in 83% of the samples (n=40). The highest mean TMDD concentrations were found in recycled toilet paper (0.20 μg/g) and in paper towels (0.11 μg/g). In paper tissues and non-recycled toilet paper the mean TMDD concentrations were lower 0.080 μg/g and 0.025 μg/g respectively. According to these results the high TMDD influent concentrations found previously in municipal WWTPs (mean 1.20 μg/L) cannot be explained due to migration of TMDD from the household paper products into the sewage. Thus indirect industrial dischargers are the cause of the high influent TMDD concentrations. Effluents of municipal WWTPs with different indirect industrial dischargers (textile-, metal processing-, food processing-, electroplating-, paper-recycling- and printing ink factories) were analyzed. The highest mean TMDD concentrations were found in the effluents of municipal WWTPs that have paper-recycling (71.3 μg/L) and printing ink factories (138 μg/L) as indirect industrial dischargers. These results were confirmed by analyzing process wastewater of three paper-recycling factories located in Germany. High TMDD concentrations were detected and fluctuated between 1.83 μg/L and 113 μg/L. TMDD was also analyzed in the wastewater of a non-recycling-paper factory but its concentration was much lower (0.066 μg/L) indicating that TMDD is introduced into the processing water during the papermaking process due to the use of waste paper. Analyses of wastewater samples from different parts of the sewage pipes of a municipal WWTP in Hesse, which receives the wastewater from a printing ink factory, were carried out. The TMDD concentration in the wastewater sample from the sewage pipe of the printing ink factory was much higher (3,300 μg/L) than the TMDD concentration detected in the other wastewater samples from the sewage system (0.030 μg/L – 0.89 g/L). These results confirm the printing ink production as one of the principal sources of TMDD in the sewage. Analysis of surface water samples of the River Modau downstream from the effluent of the WWTP Nieder-Ramstadt showed TMDD concentrations of up to 28.0 μg/L. These high TMDD concentrations might be caused by the indirect wastewater discharges of a paint factory connected to the municipal sewage system. These results indicate that TMDD is introduced into the municipal WWTPs principally by indirect industrial dischargers and they are mainly paint and printing ink factories. The paper-recycling factories also represent an important source of TMDD in municipal WWTPs but indirectly. According to statements given by the representatives of two paper recycling factories neither TMDD or any other TMDD containing product is used or added during the papermaking process. Therefore, TMDD is washed out from the printing inks of the coloured waste paper and concentrated in the process wastewater in the closed water circuits of paper-recycling factories reaching rivers and municipal WWTPs. The occurrence and distribution of TMDD in surface waters in Germany was also studied. The results showed that TMDD is widely distributed across different rivers systems in the federal states of Hesse, North-Rhine-Westphalia, Bavaria, Baden-Wuerttemberg and Rhineland-Palatinate. In Hesse, TMDD was detected in the some of main rivers with mean concentrations of 812 ng/L (Schwarzbach, Hessian Ried), 374 ng/L (Kinzig), 393 ng/L (Main, at Frankfurt), 539 ng/L (Werra), 326 ng/L (Fulda), 151 ng/L (Emsbach) and 161 ng/L (Nidda). In small rivers (creeks) the mean TMDD concentrations varied between <LOQ (Diemel, Urselbach) and 1890 ng/L (Darmbach). The results showed that the TMDD concentrations in creeks are highly influenced by both effluents of WWTPs and by the distance between the sampling point and the nearest WWTP. Surface samples from sampling locations downstream from WWTPs dischargers showed higher TMDD concentrations (mean 518 ng/L) than sampling locations upstream from WWTPs dischargers (mean 35.1 ng/L). The behavior of TMDD during bank filtration was investigated at two locations, at a water utility company at the Lower River Rhine (urban area) and at the Oderbruch polder (rural area). The results indicated that TMDD is removed from the surface water by bank filtration at both sampling locations. The removal process is probably carried out in the first meters of the aquifer (hyporheic zone) by biodegradation processes, since TMDD does not tend to be absorbed by sediments and it was not found in the groundwater of monitoring wells. In groundwater samples from the Hessian Ried (n=23) TMDD was found only in five samples and the highest TMDD concentration was 135 ng/L. According to these results, TMDD does not represent a concern for drinking water in Germany, since it does not reach the groundwater with high concentrations and it has a low toxicity potential. The input of TMDD into the North Sea was estimated to be 60.7 t/a by considering the mean transported loads of TMDD by the River Rhine at Wesel (58.3 t/a) and Meuse in the Netherlands (2.40 t/a). The estimated discharge of TMDD by German municipal WWTPs (8.19 t/a) and paper-recycling factories (9.24 t/a) into rivers seems to be too low considering that the mean TMDD load in the River Rhine downstream from Wesel is 58.3 t/a. However, due to the high density of population and industries at the Lower Rhine it is expected that more relevant sources of TMDD are located along the Rhine River increasing the transported load. According to the results of this PhD project TMDD is a non-ionic surfactant contained in products, which are applied on surfaces (printing inks and paints) and has the potential to reach the aquatic environment. Therefore, TMDD should fulfill the requirement of a biodegradability of 80% established by the “Law on the Environmental Impact of Detergents and Cleaning Products” in Germany. However, due to the partial elimination rates of TMDD obtained in municipal WWTPs (between 33% and 68%) and to the absence of information about the execution of the biodegradation test on TMDD, it is unknown if TMDD is in accordance with this law. Otherwise, its use as surfactant in such products is questionable.
The aim of this study is a better understanding of radiation processes in regional climate models (RCMs) in order to quantify their impact and to reduce possible errors. A first important task in finding an answer to this question was to examine the accuracy of the components of the radiation budget in regional climate simulations. To this end, the simulated radiation budgets of two regional climate simulations for Europe were compared with a satellite-based reference. In the simulations with the RCM COSMO-CLM there were some serious under- and overestimations of short- and long-wave net radiation in Europe. However, taking into account the differences in the reference datasets, the results of the COSMO-CLM were quite satisfactory.
Using statistical methods, the influence of potential sources of uncertainties was estimated. Uncertainties in the cloud cover and surface albedo had a significant impact on uncertainties in short-wave net radiation, the explained variance of uncertainties in cloud cover was two to three times higher than that of uncertainties in surface albedo. Uncertainties in the cloud cover resulted in significant errors in the net long-wave radiation. However, the influence of uncertainties in soil temperature on errors in the long-wave radiation budget was low or even negligible. These results were confirmed in a comparison with simulations of the REMO and ALADIN regional climate models. It is reasonable to expect that a better parameterization of relatively simple parameters such as cloud cover and surface albedo is a means of significantly improving the simulation of radiation budget components in the COSMO-CLM.
An important question for the application of RCMs is to examine whether the results of radiation uncertainties and their impact factors are comparable if the model is applied in a region that is not the one for which it was originally created. Comparisons of the simulated radiation budgets of different RCMs for West Africa showed that problems in the simulation of short- and long-wave radiation fluxes were a widespread problem. Most of the tested models showed some considerable under- or overestimation of the short- and long-wave radiation fluxes.
Similar to Europe uncertainties in cloud cover were also in the simulations for Africa a significant factor affecting uncertainties in the simulated radiation fluxes. However, for the African simulations uncertainties in the parameterization of surface albedo were much more important than in Europe. On average, overland uncertainties in the cloud cover and surface albedo were of similar importance. Uncertainties in soil temperature simulations were of higher importance in Africa, and reached overland similar values of the mean explained variance (R2 ≈ 0.2) such as uncertainties in the cloud cover. This indicates a geographical dependence of the model error. This study confirmed the assumption that an improved parameterization of relatively simple parameters such as the surface albedo in RCMs leads to a significant improvement in the modeled radiation budget, particularly in Africa.
The influence of errors in the simulated radiation budget components on the simulation of climate processes, such as the West-African monsoon (WAM), was investigated in a next step. The evaluation of ERA-Interim and ECHAM5 driven COSMO-CLM simulations for Africa showed that the main features of the WAM were well reproduced by the model, but there were only slight improvements compared to the driving data. The index of convective activity in the model simulations was much too high and precipitation was underestimated in large parts of tropical Africa. The partly considerable differences between the ERA-Interim and ECHAM5 driven simulations demonstrated the sensitivity of the RCM to the boundary conditions and in particular to the sea surface temperature. An excessive northwards shift of the monsoon in the model was influenced by the land-sea temperature gradient and the strength of the Saharan heat low. Consequently, a part of the error was due to the driving data and the model itself produced another part.
By modifying the parameterization of the bare soil albedo the errors in the radiation budget and 2 m temperature in the Sahara region were significantly reduced. Similarly, the overesti-mation of precipitation and convection has been reduced in the Sahel. The effect of this modifi-cation on the examined WAM area was low. This confirmed that especially in desert regions, errors in the surface albedo were a driving factor for errors in the radiation budget. However, there are other important factors not yet sufficiently understood that have a strong influence on the quality of the simulation of the WAM.
The analysis of the actual state, the quantification of error sources and the highlighting of connections made it possible to find means to reduce uncertainties in the simulated radiation in RCMs and to have a better understanding of radiation processes. However, the magnitude of the errors found, the number of possible influencing factors, and the complexity of interactions, indicate that there is still a need for further research in this area.
Owing to long-term similarities with regard to orbital climate forcing (i.e., low eccentricity and a dampened influence of precession), Marine Isotope Stage (MIS) 11 represents one of the closest astronomical analogues for present and future climate. Hence, insights into the climate variability of MIS 11 can contribute to a better understanding of the climatic evolution of the present (Holocene) interglacial as it would occur without human interference. In order to elucidate the natural climate variability during MIS 11, this study examines predominantly annually laminated lake sediments of Holsteinian age from Dethlingen, northern Germany. The Holsteinian interglacial is widely accepted to be the terrestrial equivalent of MIS 11c in central Europe and can be biostratigraphically correlated with the Hoxnian, Mazovian and Praclaux interglacials on the British Isles, in Poland and in France, respectively. These correlations yield the potential to cross-check the results from individual sites on a regional scale. This study is based on a multi-proxy approach including palynological, micropaleontological, sedimentological, geochemical and time series analyses within a wellconstrained chronological framework that has been established through varve counting and regional bio-stratigraphic correlations with other annually laminated archives of Holsteinian age. In particular, the here-presented study aims at (i) fingerprinting the long-term (centennial- to millennial-scale) and short-term (sub-decadal- to decadal-scale) climate variability during the Holsteinian interglacial, (ii) deciphering the nature, tempo and trigger mechanisms of abrupt climate change under interglacial boundary conditions, and (iii) assessing its impact on terrestrial ecosystems. With regard to long-term climate variability, the vegetation succession at Dethlingen as inferred from pollen data provides insights into the mesocratic to telocratic forest phases of a glacial-interglacial cycle spanning ~11500 (± 1000) years of the 15-16-ka-long Holsteinian interglacial. The development of temperate mixed forests suggests a general prevalence of mild climatic conditions during the Holsteinian. The older parts of the interglacial are characterised by the strong presence of boreal tree taxa (e.g., Picea), whereas the younger parts of the interglacial are marked by the expansion of sub-Atlantic to Atlantic forest elements (e.g., Abies, Buxus, Ilex, Quercus) and the decline of boreal tree taxa. This vegetation succession suggests a general warming trend and decreasing seasonality over the course of the Holsteinian interglacial. Based on the maximum pollen abundances of indicator tree taxa (e.g., Buxus and Quercus), peak warmth was reached during the later stages of the interglacial; it was accompanied by high humidity. The forest succession of the Holsteinian interglacial was punctuated by abrupt and gradual changes in the abundances of temperate plant taxa. These vegetation changes indicate considerable intra-interglacial climate variability. In particular, two marked declines of temperate taxa leading to the transient development of boreal and sub-boreal forests were triggered by centennial-scale climate oscillations, here termed Older and Younger Holsteinian Oscillations (OHO and YHO). These oscillations occurred ~6000 and ~9000 years after the onset of the interglacial pioneer forestation in central Europe, respectively. To assess the impact of abrupt climate change on terrestrial ecosystems during the Holsteinian and to investigate the underlying driving mechanisms, the intervals spanning the OHO and the YHO at Dethlingen were subjected to decadal-scale palynological and sedimentological analyses. Based on these data, the OHO comprises a 90-year-long decline of temperate taxa associated with expansion of Pinus and non-arboreal pollen, and a subsequent 130-year-long recovery of temperate taxa marked by the pioneer expansion of Betula and Alnus. Owing to its highly characteristic imprint on vegetation dynamics, the OHO can be identified in pollen records from the central European lowlands north of 50º latitude, from the British Isles to Poland. A close inspection of individual pollen records from that region reveals the prevalence of colder winters during the OHO, with a gradient of decreasing temperature and moisture availability, and increased continentality towards eastern Europe. This climate pattern points to a weakened influence of the westerlies and/or stronger influence of the Siberian High connected to the OHO. The vegetation dynamics during the YHO are characterised by a decline of temperate taxa (particularly of Carpinus) and the expansion of pioneer trees (mainly Betula). In contrast to the OHO, frost-sensitive taxa (e.g., Ilex, Buxus and Hedera) continued to thrive. This suggests that mean winter temperatures remained relatively high (>0 ºC) during the YHO pointing to a decrease of summer warmth related to the climatic deterioration. The YHO, which has a duration on the order of 300 years, is centered within a long-term (~1500-year) decline and subsequent, millennial-scale recovery of temperate taxa. Because the impact of the OHO and the YHO on the vegetation at Dethlingen was markedly different, both short-term climate oscillations may have been caused by different trigger mechanisms. For the OHO, the inferred regional-scale winter cooling over central Europe lasting for several decades points to a decrease in ocean heat transport, most likely related to a transient slowdown in North Atlantic Deep Water formation. This view is supported by the strong resemblance of the OHO to the 8.2 ka event of the Holocene with regard to the duration, imprint on terrestrial ecosystems, spatial pattern of the climatic impact, timing within the respective interglacial, and prevailing interglacial boundary conditions. In contrast, the presence of frost-sensitive taxa during the YHO appears to exclude a reduction in oceanic heat transport as postulated for the OHO. Instead, the long-lasting, gradual changes in the abundances of temperate taxa suggest a connection to orbital forcing, with the triggering mechanism causing the centennial-scale vegetation setback itself remaining unclear. The characteristics of short-term climate variability were investigated based on microfacies and time series analyses of a ~3200-year-long, annually laminated window of the Dethlingen record. The annual laminations at Dethlingen comprise biogenic varves consisting of two discrete sub-layers. The light layers, which are controlled by the intensity of diatoms blooms during spring/summer, reflect changes in the productivity of the Dethlingen palaeolake. In contrast, the dark layers, which consist predominantly of amorphous organic matter and fragmented diatom frustules, represent sediment deposition during autumn/winter. Spectral analyses of the thicknesses of the light and dark layers have revealed several peaks exceeding the 95% and 99% confidence levels that are near-identical to those known from modern instrumental data and Holocene records. Decadal-scale signals at periods of 90, 25, and 10.5 years are likely associated with the 88-, 22- and 11-year solar cycles; hence, solar activity appears to have been a forcing agent in productivity changes of the Dethlingen palaeolake. Sub-decadal-scale signals at periods between 3 and 5 years and ~6 years may reflect an influence of the El Niño-Southern Oscillation (ENSO) and the North Atlantic Oscillation (NAO) on varve formation during winter.
The Alborz Mountains are forming a ~100 km wide, E-W trending mountain chain where individual summits are up to 5000 m in elevation. The Alborz Mountains range are part of the Alpine orogen and are straddling a 2000 km wide area S of the Caspian Sea. The rocks of the Alborz Mountains consist of Neogen sediments, which are affected by folding and faulting. In the western part of the Alborz Mountains the folds and faults are trending NW-SE, whereas in the eastern part they are trending NE-SW. GPS data confirm N-S shortening including dextral strike-slip along ESE-WNW trending faults, and sinistral strike-slip along ENE-WSW trending faults. The present thesis is focusing on the active Garmsar salt nappe, the fragmented roof of which is pierced by rock salt which extruded near the front of the Alborz Mountains Range. During the past 5 m.y. the front of the Alborz chain migrated towards SSW on top of the salt of the Garmsar basin. The salt was squeezed towards SSW and took place at the Great Kavir. The extruded salt is forming the Eyvanekey plateau between the cities of Eyvanekey and Garmsar. Both the Garmsar salt nappe and the Eyvanekey plateau are dextrally displaced for ca. 9 km along the Zirab-Garmsar fault. Structural analyses of the Garmsar salt nappe indicate three different groups of joints which are trending perpendicular and parallel to the local mechanical anisotropy. The folds of the study area are congruent (type 2 and 3 after Ramsay) resulting from viscose inhomogeneous flow. InSAR-Investigations suggest the Alborz Mountains to be lifted up by ca. 1 cm/a, while horizontal shortening is active at a rate of 8 ±2 mm/a. These values are consistent with GPS data. Based on nine „Advanced Synthetic Aperture Radar“ (ASAR) scenarios, produced by the ENVISAT satellite of the European space agency between 2003 and 2006, we used interferograms to map the displacement via 22 increments during 2 – 18 months. The results suggest that the topographic height of the surface of the salt is changing at a rate which is controlled by the season. The displacement ranges from subsidence at -40 to -50 mm/a to uplift of 20 mm/a. In order to investigate the time-dependent deformation with high spatial resolution, we used algorithms which are based on data of small base lines (SBAS). The resulting interferometric SAR time series analyses also suggest that the study area is largely subsiding at a rate that is controlled by the seasons. The map with the averaged LOS deformation velocities, on the other hand, suggests the subsidence to increase from the upper part of the salt nappe towards deeper topographic 5 levels of the agricultural lowlands. The major part of subsidence is probably caused by the annual rainfall which results in subrosion of salt. The spatial changes in the subsidence rate are probably controlled by the distribution of fountains, mining activity at the margin of the salt glacier, and faults and fractures inside the salt. Striking seasonal imprints are obvious along the agricultural areas which are surrounding the Garmsar salt nappe. These areas are rapidly subsiding in summer and spring when groundwater is used for irrigations. The maximum rate of subsidence (40-50 mm/a) is located E and W of the Eyvanekey plateau, where large areas are irrigated. The maximum displacement is 20 mm/a in the farmland and 5 mm/a in the center of the salt nappe. Depth estimates using Euler deconvolution method for gravimetric and magnetic data suggest the salt to extrude from a depth less than ca. 2000 m. The gravity field of the study area is characterized by strong anomalies in the SW and weak anomalies in the NE. A considerable negative anomaly in the N indicates that the northern part subsided, whereas the southern part was lifted up. The seismic data show three major horizons inside the Miocene sediments: the Lower Red Formation, the Qom Formation, and the Upper Red Formation. The western part of the study area seems to be free from salt domes. The layers of the upper part of the Qom Formation show thinning along the NE and NW trending faults. In some areas the seismic reflectors indicate steep faults close the saddle of the folds. NE-SW-, NW-SE and E-Wtrending faults prevail. Analogue experiments have been carried out to extend our knowledge about the evolution of the Garmsar salt dome. We used a scaled model (34 cm * 25 cm * 2.5 cm) that was shortened perpendicular to its long side. The wedge shape of the Alborz Mountains was simulated by a wedge consisting of Styrofoam. Rock salt was simulated using Polydimethylsiloxan (PDMS), a linear viscous material with a viscosity of 2.3*104 Pa s and a density of 0.96 g/cm3 at room temperature. Other sediments were modeled using dry quartz sand. The experimental results can be used to simulate the structural evolution of the study area: The Alborz deformation front was emplaced on top of the salt rocks in the Garmsar area while migrating towards SSW. A salt basin and a salt extrusion have also been produced in the model. Cross sections through the wedge shaped analogue model indicate N- and S-dipping reverse faults, which are in line with the wedge shape of the Alborz chain. Moreover, ENE-WSW trending sinistral and ESE-WNW trending dextral strike-slip faults led to N-S shortening during the Miocene. Structural marker horizons, 6 which have been turned into Z-folds on the western fold limbs and to S-folds on the eastern fold limbs, are comparable with the folds of the study area. Solving the problem of waste is one of the central tasks of environmental protection. It is becoming increasingly difficult to find suitable sites that are acceptable to the public. Salt and salt formations have relevant properties to be utilizing as a repository for each kind of waste. The favorable properties make rock salt highly suitable as a host rock, in particular for nonradioactive and radioactive wastes. The Qom and Garmsar basins are the nearest salt diapirs to the Tehran province, and there are suitable repositories for waste disposal. Based on surface and subsurface data, the Garmsar salt diapir has been investigated as a case example for its suitability as a host and repository for various types of waste. The data used are based on field studies, interferometry, and geophysical investigations. The results of this study suggest the deep bedded salt of the Garmsar Salt Basin to be an appropriate host for the deposition of industrial waste. Rock salt of surficial layers or domes, on the other hand, is not regarded as an appropriate candidate for waste disposal.
Die kumulative Dissertation beschäftigt sich mit der atmosphärischen Konzentration von Eiskeimen, einer Unterklasse des atmosphärischen Aerosols, die bei der Eisbildung in Wolken eine zentrale Bedeutung besitzt. Messungen der Eiskeimkonzentration am Taunusobservatorium (Kleiner Feldberg) (nahe Frankfurt am Main) wurden mit dem Verfahren einer Vakuum-Diffusionskammer durchgeführt. Die Arbeit umfasst die Darstellung des angewandten Messverfahrens und die Analyse und Bewertung der Messergebnisse für den Raum Zentraleuropa, anhand von u.a. Rückwärtstrajektorien und Korrelationen zu aerosolphysikalischen Parametern. Ein signifikanter Einfluss von Mineralstaub-Ferntransport aus Wüstengebieten auf die Eiskeimkonzentration in Zentral-Europa wurde ermittelt.
Forty two samples of the Late Eocene Kiliran oil shale, Central Sumatra Basin, Indonesia were collected from a 102 m long drill core. The oil shale core represents the deposition time of about 240.000 years. Palynofacies and geochemical analyses have been carried out to reconstruct the paleoenvironmental conditions and paleoecology during deposition of the oil shale. Amorphous organic matter (AOM) is very abundant (>76%). B. braunii palynomorphs are present (3-16%) as the only autochtonous structured organic matter and generally more abundant in the middle part of the profile. The stable carbon isotopic composition of bulk organic matter (13C) varies from -27.0 to -30.5‰ and is generally more depleted in the middle part of the profile. The ratio of total organic carbon to sulfur (TOC/S), used as salinity indicator, ranges from 2.5 to 15.8 and shows variations along the profile. Slightly less saline environments are observed in the middle part of the profile. Fungal remains are generally present only in this part with a distinct peak of abundance. The presence of fungal remains is regarded as an indication for a relatively warmer climate during deposition of the middle part of the profile. The warmer climate is thought to influence the establishment of a thermocline, limiting the supply of recycled nutrients to epilimnion. Consequently, the primary productivity in the Kiliran lake decreased during deposition of the middle part of the profile as indicated by the relatively depleted 13C values and the blooming of B. braunii. The chemocline was also shoaling during the deposition according to the higher abundance of total isorenieratane and its derivatives originated from green sulfur bacteria dwelling in the photic zone euxinia. The warmer climate is also thought to influence the slightly decrease of water salinity during deposition of the middle part of the profile. The occurrence of B. braunii in Kiliran lake is also recognized from organic geochemical data. The distribution of n-alkanes is characterized by the unusual high amount of C27 n-alkane relative to the other long-chain n-alkanes. The concentrations of C27 n-alkane vary from 30.1 to 393.7 μg/g TOC and are generally in parallel with the abundances of B. braunii palynomorphs along the profile. The 13C values of this compound are about -31‰ and up to 2‰ enriched relative to those of the adjacent long-chain n-alkanes. B. braunii race A can thus be regarded as the significant biological source of the C27 n-alkane. Lower amounts of lycopane are observed in many oil shale samples (0 to 54.7 μg/g TOC). The 13C value of this compound is 17.2‰. This strong enrichment of 13C suggests that the lycopane was derived from B. braunii race L. The concentrations of lycopane develop generally in opposite with those of C27 μalkane. It is likely that both B. braunii races bloomed in alternation in the lake, probably due to changes on specific water chemistry. Norneohop-13(18)-ene and neohop-13(18)-ene derived from methanotrophic bacteria are the dominant hopanoid hydrocarbons. The sum of their concentrations varies from 40.6 to 360.0 μg/g TOC. The 13C of these compounds are extremely depleted (-45.2 to -50.2‰). The occurrence of abundant bacteria including methanotrophic bacteria was responsible for the recycling of carbon below the chemocline of the lake. The effect of the recycling of carbon is observed by the presence of a concomitant depletion (about 7-9‰) in 13C of some specific biomarkers derived from organisms dwelling in the whole phototrophic zone. 4-Methylsterane and 4-methyldiasterene homologues occur in the oil shale as the predominant biomarkers. The sum of the concentrations of all homologues are about 40.3-1,009.2 μg/g TOC with generally higher values in the uppermost and lower parts of the profile. Calcium (Ca) accounts as the predominant element in the oil shale, ranging from 5.0 to 16.7%. This element shows generally parallel variation with the 4-methylsterane and 4-methyldiasterene homologues along the profile. This suggests that these compounds were derived from biological sources favoring more alkaline and more trophic environments. On the other hand, these compounds were less abundant in the middle part of the profile which is consistent with less alkaline and less trophic environments promoting B. braunii to bloom. Alternation between Dinoflagellates and B. braunii in ancient lacustrine environments due to water chemistry changes have been known from previous studies. In the present case, distinct alternation between B. braunii abundances and concentrations of 4-methylsterane and 4-methyldiasterene homologues along the studied oil shale profile suggest a hypothesis that these compounds were derived from freshwater Dinoflagellates although dinosterane is not present in the sediment extracts. Water alkalinity and trophic level changes were most likely responsible for the alternation of Dinoflagellates and B. braunii blooming.