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The control and ban of man-made long-lived ozone-depleting substances (ODSs) by the Montreal Protocol is expected to result in the recovery of the stratospheric ozone layer in the course of the 21st century. However, short-lived ODSs, which belong to the very short-lived substances (VSLSs), are not controlled and also participate in stratospheric ozone depletion through catalytic cycles. VSLSs are produced naturally from macroalgae and phytoplankton, and anthropogenically as disinfection by-products (DBPs) from chemical treatment of industrial water. Chemical treatment of seawater, e.g. cooling water of coastal power plants, mainly produces brominated VSLSs, with bromoform as the major DBP. Bromoform is also the largest source of organic bromine from biological marine sources to the atmosphere. However, the contribution of anthropogenic VSLSs to the global bromine budget is still unclear. Industrial water treatment has increased substantially over the last years due to strong economic growth and progressing industrialisation in East Asia and India. The increasing input of anthropogenic VSLSs from emerging industries to the environment has not been quantified yet. Given the growing importance of brominated VSLSs in the face of declining long-lived ODSs, a quantification of anthropogenic VSLS sources is urgently needed. The aim of this thesis is to quantify the environmental input of anthropogenic brominated VSLSs from industrial water treatment, their distribution in the ocean and atmosphere, and their entrainment into the stratosphere. The assessment focusses on the major DBP bromoform. The global distribution of anthropogenic bromoform sources serves as the initial release field for Lagrangian simulations of bromoform pathways in the ocean and atmosphere, and as the basis for air-sea flux calculations. Oceanic trajectory simulations are performed with the ARIANE software to analyse seasonal to annual variations of bromoform distribution. Atmospheric bromoform mixing ratios are simulated with the FLEXPART model in order to analyse the tropospheric and stratospheric distribution. Combining the climatological bottom-up air sea flux estimate with the bromoform flux from coastal power plants, the global bromine budget increases by 8–35 % to 1.9–2.2 Gmol Br a-1. Over 96 % of treated cooling water originate from the regions East-Southeast Asia, Europe, North America, India and Arabia. Bromoform is usually released close to its oceanic source. An effective transport into the stratosphere mainly takes place in the tropics, whereas in extratropical regions the majority of bromoform stays in the lower troposphere and is rapidly removed by deposition, e.g. in Europe. About half of the global anthropogenic bromoform is released in the region around East-Southeast Asia. The majority of this is discharged in the extratropics along the coasts of the Yellow, Japan and East China Seas. Still about 20 % of the bromoform from this region is entrained into the stratosphere during boreal winter due to transport towards the tropical West Pacific by northeasterly winds. The tropical West Pacific, as well as the Indian Ocean are the most efficient regions for stratospheric entrainment of bromoform. Over the Indian Ocean, tropical convection and the monsoon circulation during boreal summer transport 40–50 % of bromoform from the marine boundary layer to the stratosphere. Thereby, anthropogenic emissions contribute 10–43 % to stratospheric bromoform entrainment over the Indian Ocean, and 4–25 % over the global inner tropics. The anthropogenic sources of brominated VSLSs are predicted to increase in the future. In particular, increased bromoform emissions from growing industries in tropical regions will likely lead to more bromine input into the stratosphere. In order to reduce the uncertainties of DBP concentration in treated seawater, as well as the number of missing sources in the bromoform air-sea flux estimate, additional observations along the coasts close to the industrial areas are necessary. A better understanding of all natural and anthropogenic sources of brominated VSLSs and their future trends will thus improve estimates of the global atmospheric bromine input.

Properties of seawater in the ocean are not uniformly distributed. Characteristics in different regions and depths are significantly different. Understanding of the distribution and variation of seawater plays an important role in investigating the thermohaline circulation of the world ocean or predicting climate changes. A body of seawater that originates in a particular area and shares a common formation history always has similar properties and such a water body is defined as a water mass. Source water type defines the properties of the original water mass in the formation area. The properties of water masses do not stay constant but change along the flow path due to biogeochemical changes and also due to the mixing with surrounding water masses so that the OMP method is required to investigate the distribution of water masses. The OMP method is to calculate the best components and fractions of more water masses by analyzing water properties (potential temperature, salinity, oxygen, phosphate nitrate and silicate in this study) and solving the equations of linear mixing without assumptions. With the applications of transient tracers (such as: CFC-12 and SF6), water masses can be labeled and their mean ages (consuming time during the pathway from formation area) are calculated. Combining the distributions and mean ages, the transport time and velocities of water masses can be estimated. Die Eigenschaften des Meerwassers im Ozean sind nicht gleichmäßig verteilt. Merkmale in verschiedenen Regionen und Tiefen unterscheiden sich erheblich. Das Verständnis der Verteilung und Variation von Meerwasser spielt eine wichtige Rolle bei der Untersuchung der thermohalinen Zirkulation des Weltmeers oder der Vorhersage von Klimaänderungen. Ein Meerwasserkörper, der aus einem bestimmten Gebiet stammt und eine gemeinsame Formationsgeschichte aufweist, hat immer ähnliche Eigenschaften, und ein solcher Wasserkörper wird als Wassermasse definiert. Der Quellwassertyp definiert die Eigenschaften der ursprünglichen Wassermasse im Formationsbereich. Die Eigenschaften der Wassermassen bleiben nicht konstant, sondern verändern sich entlang des Fließweges aufgrund biogeochemischer Änderungen und auch aufgrund der Vermischung mit umgebenden Wassermassen, so dass die Optimal Multiparameter (OMP)-Methode zur Untersuchung der Verteilung der Wassermassen erforderlich ist. Bei der OMP-Methode werden die besten Komponenten und Anteile von mehr Wassermassen berechnet, indem die Wassereigenschaften (potentielle Temperatur, Salzgehalt, Sauerstoff, Phosphatnitrat und Silicat in dieser Studie) analysiert und die Gleichungen des linearen Mischens ohne Annahmen gelöst werden. Mit den Anwendungen von transienten Tracern (wie: CFC-12 und SF6) können Wassermassen markiert und ihr mittleres Alter (Zeitaufwand während des Pfads vom Formationsbereich) berechnet werden. Durch die Kombination der Verteilungen und des Durchschnittsalters können die Transportzeit und die Geschwindigkeiten der Wassermassen geschätzt werden.

Eddy covariance is a technique to measure air-sea gas exchange directly. A direct flux measurement has the advantage that, without parameterizations or major simplifications of processes. Section 3 focuses on the efflux of these aerosol predecessors together with aerosol numbers in the atmosphere. The oceanic emissions are tracked using the FLEXPART forward trajectory model, which provides the locations and the times for the satellite remote sensing. The averaged satellite aerosol numbers along the 12 h downwind trajectory were correlated with the magnitude of the oceanic sources, which was found to be a significant positive correlation. The results point to a local influence of air-sea fluxes on the aerosol number, which could give rise to local feedbacks. My investigation in Section 4 uses gas transfer velocities derived from DMS and CO2 eddy covariance measurements to describe gas transfer limitations which is caused by a wind-wave interaction. This process is parameterized using the transformed Reynolds number Retr. Below a threshold of |Retr

The North Atlantic Ocean plays a major role in climate change not least due to its importance in CO2 uptake and thus natural carbon sequestration. The CO2 concentration in its surface waters, which determines the ocean's CO2 sink/source function, varies on seasonal and interannual timescales and is mainly driven by air-sea gas exchange and biological production/respiration. However, the quantification of these processes is still afflicted with a high degree of uncertainty. In this thesis, a cavity ringdown spectrometer (G2131-i, Picarro, USA), which is able to measure the CO2 mole fraction and it's stable carbon isotope composition, was installed on a VOS line that regularly sails across the subpolar North Atlantic between North America and Europe. From summer 2012 to the end of 2014, two and a half years of d13C(CO2) underway data was obtained along with continuous measurements of temperature, salinity and fCO2. Combined with a discrete sampling program (consisting of DIC, TA, nutrients, Chl a, POM, DOC, d13C(POC) and d15N(PON) samples), the dynamics of the upper North Atlantic Ocean were studied. This analysis comprises interannual variations of fCO2 and d13C(CO2), relative changes of nutrient concentration in comparison with C:N ratios of suspended particle matter, biologically and mixing driven variability in DIC and d13C(DIC) and the fractionation between dissolved CO2 and particulate matter. Based on the variations in DIC, fCO2, DIC, fCO2, d13C(DIC), nitrate, phosphate and silicate, the respective change rates and overall inventory changes due to air-sea gas exchange, net community production and convective mixing were calculated utilizing a box model.

A new, near-coastal background site was established for observations of greenhouse gases (GHGs) and atmospheric oxygen in the central Namib Desert near Gobabeb, Namibia. The location of the site was chosen to provide observations in a data-poor region in the global sampling network for GHGs. Semi-automated, continuous measurements of carbon dioxide, methane, nitrous oxide, carbon monoxide, atmospheric oxygen, and basic meteorology are made at a height of 21 m a.g.l., 50 km from the coast at the northern border of the Namib Sand Sea. Atmospheric oxygen is measured with a differential fuel cell analyzer. Carbon dioxide and methane are measured with an early-model cavity ring-down spectrometer; nitrous oxide and carbon monoxide are measured with an off-axis integrated cavity output spectrometer. Instrument-specific water corrections are employed for both instruments in lieu of drying. The representativity of the site was assessed within the context of atmospheric transport. During austral summer, strong equatorward winds are present as a result of the Hadley circulation. This brings marine boundary layer air inland to Gobabeb. In austral winter, the descending branch of the southern Hadley cell is at the same latitude as NDAO, which encourages the establishment of anticyclonic conditions over southern Africa. The variability of air mass history during this time of year is quite high, alternating between marine and terrestrial air masses, as well as air that was recently in contact with the surface and air that had descended from heights greater than 2 km. NOAA ask samples taken at Gobabeb from 1996 to the present appeared to respond to these seasonal patterns in atmospheric dynamics, when compared to other marine background sites at the same latitude as NDAO. Two years of data are presented from the observatory. Diurnal variability was noted at times for all species, particularly for atmospheric oxygen. Through stoichiometry and phasing, this was attributed primarily to the local wind system, which features a prominent sea breeze, and daily boundary layer oscillations. Large anomalies in carbon monoxide and methane were observed in the time series on a synoptic time scale, during the ascending portion of the seasonal cycle. These were attributed to an alternation between polluted air masses from the continental interior and marine boundary layer air. The continental air masses were progressively in uenced by biomass burning as the fire season developed. The concentration of re activity close to the station increased throughout the year, peaking in September, a fact re ected in the enhancement ratio of CH4 to CO. During such synoptic events the molar exchange ratio of O2 to CO2 also supported this interpretation. Finally, the NDAO time series was used to make top-down estimates of air-sea fl uxes of the main measurands from the Lüderitz and Walvis Bay upwelling cells in the Benguela Current region, during upwelling events. Flux densities were evaluated using shipboard measurements within the study area, showing good agreement with the top-down estimates. Average flux densities for CO2 were 0.450.4 µmol m-2 sec-1, -3.92.6 µmol m-2 sec-1 for O2, 6.05.0 nmol m-2 sec-1 for CH4, 0.50.4 nmol m-2 sec-1 for N2O, and 2.71.7 nmol m-2 sec-1 for CO. N2O uxes were fairly low, in accord with previous work, suggesting that the evasion of this gas from the Benguela is smaller than in other upwelling systems. Conversely, methane release was very high for the marine environment, which adds to mounting evidence of a large sedimentary source of methane in the Walvis Bay area. Carbon dioxide and oxygen uxes were substantial and probably not accounted for in current budgets.

This thesis includes three manuscripts. The first describes the ventilation of the Mediterranean Sea in 2011 based on multiple transient tracer measurements. The second evaluates the application of different transient tracers and the IG-TTD model by using several data sets from the South Atlantic and Southern Ocean. The third manuscript intorduces a new theory about saturation states of transient tracers and provides a flux estimate of anthropogenic carbon through Fram Strait in 2012. Diese Dissertation besteht aus drei Manuskripten. Das erste Manuskript beschreibt die Ventilation des Mittelmeeres in 2011 basierend auf mehreren Spurengasmessungen. Das zweite Manuskript evaluiert die Anwendung von Spurengasen und dem IG-TTD Modell anahand diverser Datensätze aus dem Südatlantik und dem Südlichem Ozean, Das dritte Manuskript führt eine neue Theorie über Sättigungszustände der Spurengase ein und beeinhaltet eine Flussabschätzung von anthropogenem Kohlenstoff durch die Fram Straße in 2012.

Oceanic bromoform (CHBr3) and dibromomethane (CH2Br2) are the largest contributors to organic bromine in the atmosphere, while atmospheric organoiodine is significantly influenced by marine methyl iodide (CH3I) and diiodomethane (CH2I2). Halogenated hydrocarbons (halocarbons) and their degradation products are involved in ozone chemistry in both the troposphere and stratosphere. With decreasing anthropogenic atmospheric halocarbons, the impact of naturally produced halocarbons on atmospheric processes will likely increase. Many uncertainties still exist with regard to their production and degradation in the ocean, as well as to their emissions. While macroalgae have been identified as important sources of them, microalgae were shown to be halocarbon producers as well. Hence, oceanic upwelling systems might play a crucial role for open ocean emissions. The tropical ocean has not only been hypothesized to contribute largely to global halocarbon emissions, but it also may contribute to their transport into upper atmospheric layers. They may be transported in significant amounts into the tropical stratosphere by tropical deep convection. This thesis aims at reducing some of the uncertainties regarding halocarbon emissions from the tropical ocean to understand their role in a future climate. Two campaigns are covered here: MSM18/3 onboard RV Maria S. Merian investigating the Eastern tropical equatorial Atlantic during the cooling season in June and July 2011, and DRIVE (Diurnal and RegIonal Variability of halogen Emissions) onboard RV Poseidon, which focused on the Mauritanian upwelling region in June 2010. Oceanic and atmospheric halocarbon data, biological, meteorological and oceanographic parameters were collected to investigate impact factors on halocarbon emissions. The oceanic and atmospheric data were also included in the most complete halocarbon database so far, HalOcAt (Halocarbons in the Ocean and Atmosphere). Manuscripts, prepared and published on the basis of this data set, include the first manuscript (Hepach et al., in prep) that focuses on the first measurements of CHBr3, CH2Br2, CH3I and CH2I2 in the surface and the water column of the equatorial Atlantic during the Atlantic Cold Tongue (ACT) season. The second (Hepach et al., 2014) and third manuscript (Fuhlbrügge et al., 2013) cover oceanic and atmospheric abundances of CHBr3, CH2Br2 and CH3I in the Mauritanian upwelling region on a diel and regional scale. While the second manuscript investigates impact factors on emissions of these compounds, the third manuscript analyzes meteorological constraints on atmospheric halocarbons. The fourth manuscript (Ziska et al., 2013) uses the HalOcAt database to determine global emissions of CHBr3, CH2Br2 and CH3I, and estimates global contributions from different regions. In the fifth manuscript (Stemmler et al., 2013), depth profiles of CH3I measured during the DRIVE campaign are used to validate modeled profiles from the tropical open ocean using the General Ocean Turbulence Model (GOTM). The transport of emissions of CH3I into the stratosphere is calculated in the sixth manuscript (Tegtmeier et al., 2013), indicating that CH3I from the DRIVE campaign is entrained in small amounts into the stratosphere. Both upwelling systems, the Mauritanian upwelling and the equatorial Atlantic, were shown here to be source regions for CHBr3 and CH2Br2, contributing to the large emissions of these compounds from the tropical ocean. While CH3I has been found to be ubiquitously distributed in the Mauritanian upwelling region hinting towards photochemical formation there, strong implications for biological formation were found in the ACT. This agrees well to the modeled depth profiles of CH3I indicating they may be influenced both by photochemical and biological formation of this compound. Although it has been hypothesized that the tropical ocean may not contribute to CH2I2 emissions to the atmosphere due to its very rapid photolysis, CH2I2 could be detected in low concentrations in the surface water of the ACT. The first determination of diapycnal fluxes of CHBr3, CH2Br2, CH3I and CH2I2 in the ACT indicate that their production takes place within the mixed layer regardless of deeper biomass maxima, which may be very important for their emissions. In the Mauritanian upwelling, oceanic halocarbon production was identified as the main driver of halocarbon emissions with wind speed having impact on a diel scale. For the first time, the height of the Marine Atmospheric Boundary Layer (MABL) has been found to indirectly impact halocarbon emissions due to its decreasing and increasing effect on atmospheric halocarbons. Together with enhanced emissions of halocarbons, the largely elevated atmospheric halocarbons above the Mauritanian upwelling could be explained solely by local emissions in contrast to previous hypotheses. This process could be of importance in other coastal upwelling systems as well.

The trace metal manganese (Mn) plays a significant role in seawater as it is bio-essential for phytoplankton. Mn plays a critical role as a redox center in Photosystem II (PSII) during the conversion of water to oxygen in photosynthesis. It is also essential in other redox related enzymatic processes; in particular Mn is important as the active metal center in superoxide dismutase (SOD) which provides intracellular protection against oxidative stress due to photochemically produced superoxide (O2 ). Mn exists in seawater in three redox states: soluble and prevalent Mn(II), insoluble Mn(III) and Mn(IV)-oxides. In the euphotic zone the biogeochemical cycling of Mn is strongly influenced by reactive oxygen species (ROS). The highly reactive and short-lived superoxide (O2 ) and hydrogen peroxide (H2O2) can both act as oxidants and reductants, and they play a key role in the Mn processes in seawater. For example the dominant Mn sources to the open ocean are the Mn-oxides which are present in atmospheric dust which are reduced to soluble Mn(II) by photochemically produced H2O2. While these processes have been crudely identified, the dominant reactions and mechanisms of Mn and ROS in seawater are poorly understood. This lack of knowledge demands investigations into the in-situ dissolution processes of Mn from dust and into studying the exact reaction mechanisms between Mn and ROS in the euphotic zone. This thesis comprises four manuscripts. Manuscripts 1 and 2 (Wuttig et al., subm., 2013a; Wuttig et al., subm., 2013b) focus on the cycling and reaction mechanisms of Mn and ROS. Manuscript 3 (Wuttig et al., in prep., 2013) addresses differences in the input and distribution of cadmium (Cd), iron (Fe) and Mn in the Eastern Tropical Atlantic Ocean off Cape Verde, and manuscript 4 (Wuttig et al., 2013) describes Mn cycling after dust additions in a trace metal clean mesocosm experiment in the Mediterranean Sea. This study has conclusively shown that Mn and organic matter are the dominant sinks for O2 in the Eastern Tropical North Atlantic (manuscripts 1; Wuttig et al., subm., 2013a). Mn dominates this decay especially in the surface waters which are influenced by high atmospheric dust deposition and near the sediment/water interface due to Mn sediment resuspension. This contrasts with current knowledge based on findings from the Mn poor Southern Ocean where copper (Cu) was shown to be the major sink. In manuscript 2 it is demonstrated that O2 decays by reaction with inorganic Mn(II) in seawater following a first order loss rate which appears to involve a catalytic reaction involving the Mn(II)/MnO2+ couple, in which MnO2+ is a manganous superoxide complex (Wuttig et al., subm., 2013a). Thus in sunlit and oxygenated waters Mn(III) is unlikely to be found in significant concentrations when strong Mn(III) binding ligands are not present. In other studies Mn(III) was found under anoxic conditions in the presence of unknown strong Mn(III) binding ligands. Therefore, in contrast to the Mn(II)/MnO2+ pair, Mn(III) cannot act as a SOD in the oxygenated surface ocean. In the Eastern Tropical North Atlantic Ocean atmospheric dust is the main source of Mn to surface waters (manuscript 3; Wuttig et al., in prep., 2013). However this study provides clear evidence that equatorial upwelling and sediment resuspension are important Mn sources in this region. In contrast to findings from the Eastern Tropical Pacific, where unexpected high surface concentrations were observed, no secondary Mn(II) maximum was found in the Eastern Tropical North Atlantic Ocean. This could have been introduced by a combination of lateral transport of Mn rich waters from the coastal margins and reduction of Mn-oxides. While Aeolian sources were predominantly influencing Mn and also Fe cycling in the Eastern Tropical Atlantic, Cd was not controlled by dust deposition (manuscript 3; Wuttig et al., in prep., 2013). These biologically relevant elements exhibited contrasting distribution patterns. For Fe and Mn, atmospheric depositions masked a classical nutrient type profile, while Cd was very depleted at the surface and concentrations steadily increased with depth. Cd was highly correlated to Phosphate (hereafter referred to as P). The Cd/P ratio was mainly controlled by P with elevated concentrations at depth resulting in strongly differing ratios in surface and subsurface layers of 16.6 pmol / µmol and 237 pmol / µmol, respectively. The complex photochemical processes during the dissolution of Mn dust are also subject of manuscript 4. This paper describes a mesocosm project in the Mediterranean with two consecutive additions of evapocondensed dust conducted. The data also show that the dissolution and loss rates of Mn were comparable during both seedings. The calculated fractional solubilities for the first and the second dust addition were 41 ± 9 % and 27 ± 19 %, respectively. The results presented in this thesis have significantly improved our understanding of Mn distribution and especially cycling in the euphotic zone. An insight into the mechanisms between Mn and ROS and into the dissolution processes from dust is given. Das Spurenelement Mangan (Mn) ist von zentraler Bedeutung im Meer, da es ein essenzieller Mikronährstoff für Phytoplankton ist. Es spielt eine wichtige Rolle im Photosystem II (PSII) bei der Sauerstoffbildung aus Wasser in der Photosynthese. Des Weiteren ist Mn wichtig für weitere enzymatische Redoxprozesse, insbesondere als aktives Metallzentrum in Superoxiddismutase (SOD), welche als intrazelluläre Schutzmechanismen vor oxidativem Stress durch photochemisch produziertes Superoxid (O2 ) fungieren. Im Meerwasser kommt Mn in drei Oxidationsstufen vor: in erster Linie als lösliches Mn(II), als unlösliches Mn(III) und als Mn(IV)-Oxide. Der biogeochemische Kreislauf von Mn im lichtdurchfluteten Ozean ist signifikant durch reaktive Sauerstoffspezies (ROS) beeinflusst. Hierbei können das stark reaktive und kurzlebige Superoxid (O2 ) und seine Tochterprodukt Wasserstoffperoxid (H2O2) gleichermaßen eine oxidierende als auch eine reduzierende Wirkung haben und spielen somit eine Schlüsselrolle für Mn Prozesse im Meerwasser. Im offenen Ozean beispielsweise ist atmosphärischer Staub die Haupteintragsquelle für Mn und das in oxidierter Form vorliegende Mn im Staub kann durch photochemisch gebildetes H2O2 reduziert und als Mn(II) im Wasser gelöst werden. Obwohl die groben Zusammenhänge dieser Prozesse bekannt sind, sind die Hauptreaktionen und Mechanismen des Zusammenspiels von Mn und ROS im Meerwasser kaum verstanden. Die Dissertation umfasst vier Manuskripte. Manuskripte 1 (Wuttig et al., subm., 2013a) und 2 (Wuttig et al., subm., 2013b) konzentrieren sich auf Kreisläufe und Reaktionsmechanismen von Mn und ROS. Manuskript 3 beschreibt die Unterschiede zwischen den Eintragsprozessen und der Verteilung von Cd, Fe und Mn im östlichen tropischen Atlantik nahe den Kapverdischen Inseln (Wuttig et al., in prep., 2013). Manuskript 4 (Wuttig et al., 2013) widmet sich der Untersuchung des Mn Kreislaufs in Folge der wiederholten Staubzugabe in das oligotrophe Oberflächenwasser von spurenmetall-sauberen Mesokosmen im Mittelmeer. Im Gegensatz zu früheren Beobachtungen im Südpolarmeer, konnte in dieser Studie klar gezeigt werden, dass im östlichen tropischen Atlantik Mn und organische Substanzen als vorwiegende Senken für O2 darstellen (Manuskript 1; Wuttig et al., subm., 2013a). Mn dominiert diesen Zerfall besonders im Oberflächenwasser, welches stark durch atmosphärischen Staubfluss beeinflusst ist, und nahe dem Meeresboden durch die Resuspension aus dem Sediment. Zudem konnte gezeigt werden, dass der Abbau von O2 durch Reaktion mit anorganischem Mn(II) in Seewasser einer Zerfallsrate erster Ordnung folgt (Manuskript 2, Wuttig et al., subm., 2013b). Diese scheint eine katalytische Reaktion des Mn(II)/MnO2+ Paars zu beinhalten, wobei MnO2+ der Superoxidkomplex ist. Des Weiteren ist es in der euphotischen und sauerstoffreichen Zone unwahrscheinlich, nennenswerte Mn(III) Konzentrationen aufzufinden, welche ohne starke Mn(III) bindende Liganden nur unter anoxischen Bedingungen erwartet werden. Somit kann Mn(III) im Gegensatz zum Mn(II)/MnO2+ Paar im sauerstoffreichen Oberflächenwasser nicht als SOD agieren. Atmosphärischer Staub ist die Haupteintragsquelle von Mn im Oberflächenwasser des östlichen tropischen Atlantiks (Manuskript 3; Wuttig et al., in prep., 2013). Jedoch wurden in dieser Region zusätzlich auch Einträge von Mn durch äquatorialen Auftrieb und Resuspension aus dem Sediment beobachtet. Zusätzlich wurde hier kein sekundäres Mn(II) Maximum gefunden, welches bei gleichen Untersuchungen im östlichen tropischen Pazifik in 200 m Tiefe der Fall war und vermutlich durch eine Kombination aus Einträgen durch atmosphärischen Staub und laterale Transportprozesse verursacht wurde. Während atmosphärische Quellen dominierend den Mn und Fe Kreislauf beeinflussen, sind Cd Konzentrationen im tropischen Atlantik nicht durch Staubeintrag kontrolliert (Manuskript 3; Wuttig et al., in prep., 2013). Generell zeigten diese Spurenelemente unterschiedliche Verteilungsmuster. Während die für biologisch relevante Elemente zu erwartenden typischen nährstoffähnlichen Tiefenprofiele durch den atmosphärischen Eintrag von Fe und Mn überlagert wurden, waren die Cd Konzentrationen im Oberflächenwasser sehr niedrig und nahmen mit der Tiefe zu. Das Cd/P Verhältnis wurde dabei in erster Linie durch die in der Tiefe erhöhten P Konzentrationen bestimmt und wies dort ein Cd/P Verhältnis von 237 pmol / µmol gegenüber 16.6 pmol / µmol im Oberflächenwasser aus. Auch im Manuskript 4 (Wuttig et al., 2013), welches sich mit der Löslichkeit und dem Kreislauf von Mn nach zwei Zugaben prozessierten Staubs während eines Mesokosmen Projektes im Mittelmeer beschäftigt, spielen die komplexen photochemischen Experimente eine zentrale Rolle. Hinzukommend zeigen die Daten, dass die Mn Löslichkeits- und Verlustraten nach den beiden Staubzugaben vergleichbar sind. Die anteilige Löslichkeit von Mn aus dem Staubmaterial betrug 41 ± 9 % für die erste Staubzugabe und 27 ± 19 % für die zweite Staubzugabe.

This thesis describes the development and field evaluation of new methods and instruments for autonomous measurements of CO2 partial pressure (pCO2) in the ocean. An autonomous profiling float conducted for the first time high resolution pCO2 measurements in the water column and at the surface in the tropical eastern North Atlantic. Along with time series data from the Cape Verde Ocean Observatory (CVOO) seasonal variability of CO2 and O2 air-sea fluxes was examined. Furthermore, episodic mesoscale oceanographic structures in the vicinity of CVOO were for the first time detected and described by means of different autonomous measurement approaches. These structures carried an extreme biogeochemical environment (subsurface anoxia), which has not been observed before in this region. Diese Arbeit beschreibt die Entwicklung und Evaluierung neuer Methoden und Instrumente für die autonome Messung von CO2 Partialdruck (pCO2) im Ozean. Ein autonom profilierender Tiefendrifter hat zum ersten Mal hochaufgelöste Messungen für pCO2 sowohl in der Wassersäule als auch im Oberflächenozean des östlichen tropischen Nordatlantiks durchgeführt. Zusammen mit Zeitserien Daten von dem Kapverdischen Ozean Observatorium (CVOO) wurde die saisonale Variabilität von CO2 und O2 Ozean-Atmosphäre-Flüssen genauer untersucht. Weiterhin konnten mittels der Kombination von unterschiedlichen autonomen Beobachtungsansätzen episodisch auftretende, mesoskalige Strukturen im Ozean bei CVOO erstmals detektiert und beschrieben werden. Diese Strukturen besitzen eine extreme biogeochemische Signatur (Anoxie unterhalb der durchmischten Deckschicht), welche in dieser Region so noch nie beobachtet werden konnte.

Increasing atmospheric CO2 concentrations equilibrate with the surface water of the oceans and thereby increase seawater pCO2 and decrease [CO32-] and pH. This process of ocean acidification is expected to cause a drastic change of marine ecosystem composition and a decrease in calcification ability of various benthic invertebrates. The studied area, Kiel Fjord, is characterized by high pCO2 variability due to upwelling of O2 depleted and CO2 enriched bottom water. Within less than 50 years, eutrophication of the Baltic Sea has drastically increased the mean pCO2 in the fjord. The observed increase and also the rate of this acidification process is much higher than it is expected for the global ocean as a consequence of increasing atmospheric CO2 concentrations. In contrast to other areas subjected to elevated pCO2, calcifying invertebrates inhabit Kiel fjord and the benthic community is dominated by the blue mussel Mytilus edulis. Mussel larvae settle in the period of the year when highest pCO2 (800-2300 µatm) are encountered, which is, at the same time, the main growth period due to highest phytoplankton densities. In laboratory experiments, calcification rates of M. edulis are maintained at elevated pCO2 levels which are expected to occur by the year 2300. Only at high pCO2 above 3000 µatm, calcification is significantly reduced. One possible reason for this tolerance is the fact that even under control conditions, the extracellular body fluids (haemolymph and extrapallial fluid, EPF) of M. edulis are characterized by low pH and [CO32-] and high pCO2. Therefore, the EPF which is in direct contact with the shell is undersaturated with calcium carbonate also at current, low seawater pCO2. Under elevated pCO2, mussels do not buffer the extracellular acidosis by means of bicarbonate accumulation. Thus haemolymph pH and [CO32-] are reduced even further. Calcification might not be affected by the extracellular acidosis, as an amorphous calcium carbonate (ACC) precursor is most probably formed in intracellular vesicles. Since mussels are able to efficiently regulate the intracellular pH, reduced extracellular pH might therefore have only little impact on the initial calcification process. On the other hand, the production of the organic shell components, e.g. the periostracum, consumes high amounts of energy. Especially in young thin shelled life stages with a higher organic shell content most of the energy allocated to growth is required for shell production. Under elevated pCO2, mussels initially (two months acclimation) up - regulate their metabolic rates which may indicate higher energy demand for ion regulatory processes. Long-term acclimated animals (12 months acclimation) probably switch to an energetically less expensive compensation and do not exhibit elevated aerobic metabolism. However, long-term acclimated mussels are characterized by lower filtration rates. As consequence, after both intermediate and long-term exposure, the scope for growth is reduced in high pCO2 acclimated animals. Additionally, after intermediate and also long-term acclimation to elevated pCO2, protein metabolism is increased, as indicated by an elevation of ammonia excretion rates. This mode of energy generation is less efficient than oxidation of lipid or carbohydrate and may contribute to lower energy availability for growth and calcification. Similar to other aquatic animals, ammonia excretion in mussels seems to be facilitated by NH3 diffusion through Rhesus (Rh) and ammonium transporter (Amt) protein channels and subsequent acid-trapping by separate proton excretion. In order to test the importance of energy supply and elevated pCO2 on mussel calcification, juvenile M. edulis were exposed to a crossed experimental design for seven weeks. Higher food supply enables mussels to calcify also under highly elevated pCO2. In general food supply is the most important factor which determines the growth rates of mussels whereas pCO2 has only a minor effect. In a simultaneous field study, mussels were transplanted to the energy rich high pCO2 inner fjord and to the outer parts of the fjord at lower pCO2 and particulated organic carbon concentrations. Similar to the laboratory experiment, mussels exhibit much higher growth rates in the high pCO2 inner fjord with its higher particulate organic carbon concentrations. This reveals the importance of energy availability impacting CO2 tolerance of M. edulis. Mussels seem to be relatively tolerant to elevated pCO2 both in laboratory experiments and under current high pCO2 conditions in Kiel Fjord. The high energy availability present in the eutrophicated habitat may support the tolerance to elevated pCO2. In the future, increasing atmospheric CO2 concentrations will drastically elevate pCO2 level in this habitat. The benthic life stages seem to be able to cope with the expected levels but plantonic larvae might be vulnerable. However, M. edulis exhibit a high adaptation potential to the rate of acidification in the recent past and might be able to adapt also to higher levels in future. In order to predict the success of M. edulis in future, also effects of elevated temperature and the response of their main predators to these conditions needs to be considered. Increasing atmospheric CO2 concentrations equilibrate with the surface water of the oceans and thereby increase seawater pCO2 and decrease [CO32-] and pH. This process of ocean acidification is expected to cause a drastic change of marine ecosystem composition and a decrease in calcification ability of various benthic invertebrates. The studied area, Kiel Fjord, is characterized by high pCO2 variability due to upwelling of O2 depleted and CO2 enriched bottom water. Within less than 50 years, eutrophication of the Baltic Sea has drastically increased the mean pCO2 in the fjord. The observed increase and also the rate of this acidification process is much higher than it is expected for the global ocean as a consequence of increasing atmospheric CO2 concentrations. In contrast to other areas subjected to elevated pCO2, calcifying invertebrates inhabit Kiel fjord and the benthic community is dominated by the blue mussel Mytilus edulis. Mussel larvae settle in the period of the year when highest pCO2 (800-2300 µatm) are encountered, which is, at the same time, the main growth period due to highest phytoplankton densities. In laboratory experiments, calcification rates of M. edulis are maintained at elevated pCO2 levels which are expected to occur by the year 2300. Only at high pCO2 above 3000 µatm, calcification is significantly reduced. One possible reason for this tolerance is the fact that even under control conditions, the extracellular body fluids (haemolymph and extrapallial fluid, EPF) of M. edulis are characterized by low pH and [CO32-] and high pCO2. Therefore, the EPF which is in direct contact with the shell is undersaturated with calcium carbonate also at current, low seawater pCO2. Under elevated pCO2, mussels do not buffer the extracellular acidosis by means of bicarbonate accumulation. Thus haemolymph pH and [CO32-] are reduced even further. Calcification might not be affected by the extracellular acidosis, as an amorphous calcium carbonate (ACC) precursor is most probably formed in intracellular vesicles. Since mussels are able to efficiently regulate the intracellular pH, reduced extracellular pH might therefore have only little impact on the initial calcification process. On the other hand, the production of the organic shell components, e.g. the periostracum, consumes high amounts of energy. Especially in young thin shelled life stages with a higher organic shell content most of the energy allocated to growth is required for shell production. Under elevated pCO2, mussels initially (two months acclimation) up - regulate their metabolic rates which may indicate higher energy demand for ion regulatory processes. Long-term acclimated animals (12 months acclimation) probably switch to an energetically less expensive compensation and do not exhibit elevated aerobic metabolism. However, long-term acclimated mussels are characterized by lower filtration rates. As consequence, after both intermediate and long-term exposure, the scope for growth is reduced in high pCO2 acclimated animals. Additionally, after intermediate and also long-term acclimation to elevated pCO2, protein metabolism is increased, as indicated by an elevation of ammonia excretion rates. This mode of energy generation is less efficient than oxidation of lipid or carbohydrate and may contribute to lower energy availability for growth and calcification. Similar to other aquatic animals, ammonia excretion in mussels seems to be facilitated by NH3 diffusion through Rhesus (Rh) and ammonium transporter (Amt) protein channels and subsequent acid-trapping by separate proton excretion. In order to test the importance of energy supply and elevated pCO2 on mussel calcification, juvenile M. edulis were exposed to a crossed experimental design for seven weeks. Higher food supply enables mussels to calcify also under highly elevated pCO2. In general food supply is the most important factor which determines the growth rates of mussels whereas pCO2 has only a minor effect. In a simultaneous field study, mussels were transplanted to the energy rich high pCO2 inner fjord and to the outer parts of the fjord at lower pCO2 and particulated organic carbon concentrations. Similar to the laboratory experiment, mussels exhibit much higher growth rates in the high pCO2 inner fjord with its higher particulate organic carbon concentrations. This reveals the importance of energy availability impacting CO2 tolerance of M. edulis. Die steigenden CO2 Konzentration der Atmosphäre und die folgende Äquilibrierung mit dem Oberflächenwasser der Ozeane führen zu erhöhten pCO2 und sinkenden Karbonationen Konzentrationen ([CO32-]) und pH Werten. Die sogenannte Ozeanversauerung hat vermutlich weitreichende Auswirkungen auf die marinen Ökosysteme und führt möglicherweise dazu, dass die Kalzifizierungsraten insbesondere benthischer Wirbelloser abnimmt. Das Untersuchungsgebiet der Kieler Förde weist, durch den Auftrieb bodennahen Wassers mit niedriger O2 Sättigung und hohen CO2 Konzentrationen, bereits heutzutage hohe und variable pCO2 Werte auf. Innerhalb der letzten 50 Jahre hat die Eutrophierung zu einer deutlichen Erhöhung der pCO2 Werte in der Förde geführt. Damit ist sowohl das Ausmaß als auch die Geschwindigkeit der Versauerung höher, als es für die weltweiten Ozeane im Zuge des zukünftigen CO2 Anstiegs zu erwarten ist. Im Gegensatz zu anderen Gebieten, die vergleichbar erhöhten pCO2 Werten ausgesetzt sind, leben zahlreiche kalzifizierende Wirbellose in der Förde und die Miesmuschel Mytilus edulis dominiert die benthische Gemeinschaft. Die Larven der Muscheln siedeln insbesondere in der Jahreszeit in der die höchsten pCO2 Werte (800-2300 µatm) auftreten. Aufgrund der hohen Phytoplanktonkonzentrationen ist dies ebenfalls die Zeit der höchsten Wachstumsraten. In Laborversuchen ist M. edulis in Lage die Kalzifizierungsraten unter erhöhten pCO2 Werten, die für das Jahr 2300 erwartet werden, aufrechtzuerhalten. Extrazelluläre Flüssigkeiten (Hämolymphe und extrapalliale Flüssigkeit, EPF) weisen auch unter Kontrollbedingungen hohe pCO2 Werte und niedrige pH und [CO32-] auf. Die EPF, die in direktem Kontakt zur Schale steht, ist demnach auch bei niedrigem Meerwasser pCO2 mit Kalziumkarbonat untersättigt. Bei erhöhtem Meerwasser pCO2 säuert sich die Hämolymphe an und wird nicht durch Bikarbonat gepuffert. Die Ansäuerung des extrazellulären Raumes hat vermutlich deshalb nur geringe Auswirkungen auf die Kalzifizierung, da ein amorpher Kalziumkarbonatvorläufer bereits in intrazellulären Vesikeln gebildet wird. Muscheln können den intrazellulären pH weitestgehend unabhängig vom Außenmedium regulieren, weshalb die extrazelluläre Ansäuerung die Schalenbildung nur geringfügig beeinflusst. Allerdings benötigt die Synthese der organischen Schalenbestandteile sehr viel Energie. Insbesondere in jungen, dünnschaligen Lebensstadien, die Schaleen mit einem höheren Organikanteil aufweisen, wird der größte Teil der für das Wachstum benötigten Energie in die Schalenbildung investiert. Unter erhöhtem pCO2, weisen Muscheln zunächst höhere metabolische Raten auf, was möglicherweise auf einen erhöhten Energiebedarf für aktive Ionentransportprozesse hinweist. Nach langer Akklimation scheinen sie auf eine effizientere Regulation zu wechseln und der aerobe Stoffwechsel ist nicht mehr erhöht. Allerdings nimmt die Filtrationsleistung ab. In beiden Fällen ist demnach die Energie, die für das Wachstum zur Verfügung steht, reduziert. Außerdem ist nach mittlerer und Langzeit-Akklimierung der Proteinstoffwechsel erhöht, erkennbar an der höheren Ammoniumexkretion. Diese Art der Energiegewinnung ist weniger effizient als Lipid- und kohlenhydratstoffwechsel und könnte zu einer verminderten Energieverfügbarkeit beitragen. Wie auch in anderen aquatischen Tieren scheint die Ammoniumexkretion in Muscheln durch Rhesus (Rh) und Ammoniumtransporter (Amt) Kanalproteine und eine anschließende Protonierung gefördert zu werden. Die Bedeutung von Energieversorgung und erhöhtem pCO2 auf die Kalzifizerung ist in einem gekreuzten Versuchsansatz getestet worden. Höhere Futterzugabe ermöglicht den Muscheln die Kalzifizierung auch unter hohen pCO2. Generell ist die Futterzufuhr von größerer Bedeutung für das Wachstums während pCO2 nur einen geringen Effekt hat. In einem zeitgleich durchgeführten Feldexperiment sind junge Muscheln in die Innenförde mit ihren hohen pCO2 und in die Außenförde mit niedrigeren pCO2 und partikulären organischen Kohlenstoffkonzentrationen verpflanzt worden. In Übereinstimmung mit dem Laborexperiment, weisen die Tiere in der inneren Förde trotz des höheren pCO2 deutlich höhere Wachstumsraten als die in der Außenförde auf. Dieses Ergebnis betont die Bedeutung der Energieverfügbarkeit für die Toleranz von M. edulis gegenüber der Ozeanversauerung. Muscheln scheinen gegenüber erhöhten pCO2 Werten in Laborexperimenten aber auch innerhalb der Kieler Förde relativ tolerant zu sein. Die hohe Energieverfügbarkeit in dem eutrophierten Habitat der Kieler Förde könnte die Toleranz gegenüber hohen pCO2 Werten fördern. Allerdings werden die steigenden CO2 Konzentrationen der Atmosphäre die pCO2 Werte der Förde zukünftig deutlich erhöhen. Während die benthische Lebensphase gegenüber den erwarteten Werten tolerant zu sein scheint, könnten the planktischen Larven sensibler sein. Allerdings wies M. edulis eine hohe Anpassungsrate an die Versauerung der jüngeren Vergangenheit auf und könnte dementsprechend auch in der Lage sein, sich an zukünftige Bedingungen anzupassen. Um verlässlich vorherzusagen, ob M. edulis auch in Zukunft erfolgreich sein wird, ist es notwendig auch die Effekte erhöhter Temperaturen und die Auswirkungen solcher Bedingungen auf die Haupträuberorgansismen zu berücksichtigen.

In dieser Arbeit wird die Entwicklung hochgenauer autonomer Messsysteme für den pH-Wert und die Gesamtalkalinität zur vollständigen Charakterisierung des Carbonatsystems in Meerwasser aufgezeigt. Es wurde die Carbonatchemie in der Nordsee vollständig beschrieben und gezeigt, wie durch eine Überstimmung des Carbonatsystems systematische Fehler der Messungen identifiziert und eliminiert werden können und somit eine Qualitätssicherung der gemessenen Daten erfolgen kann. This study presents the development of high quality measurement systems for pH and total alkalinity for a full characterization of the carbonate system in seawater. The carbonate chemistry in the North Sea has been described on the basis of an over determined carbonate system. It has been shown how systematic errors can be identified and eliminated to provide quality assured data.

The present thesis investigates the potential suitability of surface water dissolved titanium (Ti) concentrations as complementary dust tracer to dissolved aluminium (Al). Both metals reflect variations in the dust deposition into the surface ocean over different time scales, with seasonal timescales for Al and longer temporal scales for Ti. In order to lay the basis for future estimations of dust deposition from surface water concentrations of both metals, the behavior of Al and Ti is examined in the upper water column of the Atlantic Ocean. Detailed insights are given into the size distribution, removal processes and residence times of Al and Ti, in regions that largely differ in atmospheric inputs and biological productivity. Die vorliegende Dissertation untersucht die potentielle Eignung von gelösten Titan (Ti) Konzentrationen im Oberflächenozean als komplementärer Staubtracer zu gelöstem Aluminium (Al). Beide Metalle spiegeln Variationen im Staubeintrag in den Oberflächenozean über unterschiedliche Zeitskalen wieder, mit saisonalen Zeiskalen im Fall von Al und längeren Zeitskalen im Fall von Ti. Um eine Grundlage für zukünftige Abschätzungen des Staubeintrags anhand der Konzentrationen beider Metalle im Oberflächenwasser zu schaffen, wird das Verhalten von Al und Ti in der oberen Wassersäule des Atlantischen Ozeans betrachtet. Detaillierte Einblicke in die Größenverteilung, Entfernungsprozesse und Verweilzeiten von Al und Ti werden für Regionen gegeben, die sich deutlich hinsichtlich der atmosphärischen Einträge und der biologischen Produktivität unterscheiden.

The coast of Paraná State contains several ecosystems that are under permanent environmental protection, of which Paranaguá and Guaratuba bays stand out due to the great economical and ecological importance. Notwithstanding, the increase of conflicts in this area has been observed in the past years related to the failure and/or lack of appropriate government policies. The main divergences are observed between the urban and harbour development and the conservation of national ‘patrimony’ areas; between traditional and industrial fishermen; between the aquaculture and the discharge of untreated sewage to the estuaries. In this sense, there is an urgent need of supplying information and strategies for the sustainable environmental development of the area, especially concerning nutrient enrichment and the negative impacts of eutrophication. This work proposes a compilation of approaches to assess the estuarine water quality in the coast of Paraná through descriptive interpretations, definition of the trophic status by indices and the experience of performing long term monitoring for several parameters. Die Küste von des Staates Paraná vereint mehrere, unter Naturschutz stehende Ökosysteme miteinander, von denen sich Paranauá und Guaratuba wegen des hohen ökonomischen und ökologischen Interesses hervorheben. Dennoch nahmen in den letzten Jahren die Konflikte bezüglich fehlender oder ungeeigneter Regierungspolitik zu. Die wichtigsten Konfliktpunkte bestehen zwischen der Stadt- und Hafenentwicklung und der Erhaltung der Naturschutzgebiete, zwischen Traditions- und Industriefischerei, sowie zwischen Aquakultur und dem Einleiten unbehandelter Abwässer in die Ästuare. Demzufolge gibt es einen dringenden Bedarf, Informationen und Strategien für ein nachhaltiges Umweltmanagement für diese Region zu erarbeiten. Dies gilt besonders für Nährstoffanreicherungen und deren negativen Folgen.

This study presents data from the Mediterranean Sea and the tropical Atlantic Ocean. The TTD method together with tracer measurements is used to estimate water mass ages and anthropogenic carbon concentrations. With the help of alkalinity and dissolved inorganic carbon measurements the carbonate system of the Mediterranean Sea is described and CFC-12 measurements are used to estimate anthropogenic carbon concentrations, inventories and fluxes. For the tropical Atlantic Ocean CFC-12 and SF6 measurements are available and give insight into the distribution of water mass age and anthropogenic carbon in the areas of the Guinea dome and the equator. Differences between the two regions are highlighted. In dieser Arbeit werden Daten aus dem Mittelmeer sowie dem tropischen Atlantik vorgestellt. Mit der TTD Methode und Tracermessungen werden Alter von Wassermassen und anthropogene Kohlenstoffkonzentrationen abgeschätzt. Anhand von Messungen von Alkalinität und gelöstem anorganischem Kohlenstoff wird das Karbonatsystem des Mittelmeers beschrieben und CFC-12 Messungen werden genutzt um Konzentrationen, Inventare und Flüsse von anthropogenem Kohlenstoff abzuschätzen. Für den tropischen Atlantik stehen CFC-12 und SF6 Messungen zur Verfügung und geben Aufschluss über die Altersverteilung der Wassermassen sowie die Verteilung des anthropogenen Kohlenstoffs in den Gegenden des Guinea Doms und dem Äquator. Unterschiede zwischen beiden Regionen werden aufgezeigt.

The aim of this study was to analyze the annual cycle of dissolved oxygen (O2) in the central Labrador Sea on the basis of oxygen data observed by autonomous profiling floats during the period September 2003 and August 2006. The Labrador Sea in one of just a few regions where open-ocean deep winter convecion occurs reaching depths of 2000 m and more. The seasonal and interannual cycles of temperature, salinity, and oxygen are affected by physical and biological factors. The published separation of the seasonal freshwater pulse between March and September into two freshening periods as well as a slight increase of maximum sea surface temperature by 0.3°C to 0.8°C was confirmed. The seasonal oxygen cycle of the mixed layer is highly dynamic varying from moderate undersaturation during late winter to marked supersaturation in spring and early summer. The published climatological picture for oxygen was largely confirmed whereby the smoothing effect of the climatology becomes obvious. The mixed layer depth was determined using an O2 difference criterion of 5 mumol L-1 which seems to be a reasonable threshold for this region. Convective deepening of the mixed layer is associated with a strong increase of the upper ocean O2 inventory which was estimated at 8.3 to 15.1 mol O2 m-2. This inventory increase is correlated with the maximum depth of the winter mixed layer. Hence the increase found during winter 2003/2004 was largest at 15.1 mol O2 m-2. There is indication that the North Atlantic Oscillation (NAO index) affects the deep ventilation in the Labrador Sea as a correlation was found between the NAO index and the winter increase of the deep O2 inventory (710-1350 m) with a time lag of 1 year. Also, an increase of the maximum summer oxygen concentration by 17.4 mumol L-1 in surface waters was observed which is indicative of a stronger or more rapid primary production. The oxygen dataset was also used to estimate the air-sea gas transfer coefficient of oxygen as a function of wind speed. The results in general agree well with prominent published parameterizations. They fall, however, on the high end of the wind speed dependence. Best fits were found using cubic or even biquadratic functions which points at the strong importance of very high wind speed for air-sea gas exchange. Finally, the vertical flux of particulate organic matter (POC) was estimated by vertical integration of carbon remineralization rates. The latter were derived during the summer/fall period for the central Labrador Sea and the adjacent slope region from oxygen utilization rates in the mesopelagial. The data are indicative of more rapid remineralization in the slope region. The "b" parameter of the famous Martin curve for the vertical POC flux was estimated. The value for the central Labrador Sea agrees very well with more recently published values for the North Atlantic Bloom Experiment in the subpolar North Atlantic. Die Zielsetzung dieser Arbeit war es, den Jahresgang von Sauerstoff (O2) in der zentralen Labradorsee mit Hilfe von Daten zu untersuchen, die von autonom profilierenden Tiefendriftern (Floats) über den Zeitraum September 2003 bis August 2006 gewonnen wurden. Die Labradorsee ist eine von wenigen Regionen, in denen Tiefenkonvektion stattfindet, die bis zu 2000 m und tiefer reichen kann. Die jahreszeitlichen und zwischenjährlichen Schwankungen in Temperatur, Salzgehalt und Sauerstoff werden von physikalischen und biologischen Faktoren bestimmt. Die in der Literatur dokumentierte Aufteilung des jährlichen Süßwasserpulses zwischen März und September in zwei Pulse sowie ein leichter Anstieg von 0.3°C bis 0.8°C der Oberflächentemperatur wurden bestätigt. Diese Ergebnisse stimmen mit früheren Arbeiten gut überein. Der O2-Jahresgang in der Deckschicht ist von hoher Dynamik geprägt und variiert zwischen erheblicher winterlicher Untersättigung und kräftiger frühsommerlicher Übersättigung. Das publizierte klimatologische Bild wurde weitgehend bestätigt, wobei der glättende Effekt der Klimatologie offenkundig ist. Die Deckschichttiefe wurde mit Hilfe eines O2-Differenzkriteriums von 5 mumol L-1 bestimmt, was ein angemessener Schwellenwert für diese Region zu sein scheint. Durch Konvektion bedingte Vertiefung der Deckschicht ist mit einer Zunahme des O2-Inventars von jährlich 8.3 bis 15.1 mol O2 m-2 verbunden. Hierbei korreliert die Inventarzunahme in etwa mit der maximalen winterlichen Konvektionstiefe und erreicht somit im Winter 2003/2004 den größten Wert von 15.1 mol O2 m-2. Es gibt Anzeichen dafür, dass die tiefe Ventilation in der Labrardorsee von der Nordatlantischen Oszillation (NAO-Index) beeinflusst wird. So wurde eine Korrelation zwischen dem NAO-Index und der winterlichen Zunahme des tiefen O2-Inventars (710-1350 m) mit einer Zeitverschiebung von einem Jahr gefunden. Ferner wurde ein Ansteig des O2-Konzentrationsmaximums im Sommer um 17.4 mumol L-1 beobachtet, welcher auf erhöhte oder schneller akkumulierende Primärproduktion hinweist. Die gewonnenen Sauerstoffdaten wurden außerdem genutzt, um den Gasaustauschkoeffizienten von Sauerstoff als Funktion der Windgeschwindigkeit zu bestimmen. Im Allgemeinen zeigten unsere Ergebnisse eine gute Übereinstimmung mit prominenten Parameterisierungen. Dabei liegen sie jedoch am oberen Ende der Windgeschwindigkeitsabhängigkeit. Die Daten konnten mit einer kubischen oder sogar biquadratischen Funktion am besten repräsentiert werden, was auf den überproportionalen Einfluss hoher Windgeschwindigkeiten zurückzuführen ist. Im letzten Teil der Arbeit wurde der Vertikalfluss von partikulärem organischen Kohlenstoff (POC) durch vertikale Integration der Kohlenstoffremineralisationsraten bestimmt. Letztere konnten aus den beobachteten sommerlichen Sauerstoffzehrungsraten im Mesopelagial der zentralen Labradorsee und angrenzenden Kontinentalhangregion gewonnen werden. Er gibt Hinweise auf eine raschere Remineralisation des organischen Materials in der Kontinentalhangregion. Es wurde der "b"-Parameter der prominenten Martin-Funktion für den vertikalen POC-Fluss ermittelt. Dieser stimmt für die zentrale Labradorsee hervorragend mit dem in der jüngeren Literatur angegebenen Wert für das North Atlantic Bloom Experiment im subpolaren Nordatlantiküberein.

Iron solubility and ligand measurements performed during this PhD work showed that strong organic ligands increase iron solubility and therefore the residence time of Fe in seawater. Measurements made during a mesoscale Fe fertilization experiment (EIFeX) in the Southern Ocean showed that both the soluble and colloidal fractions of dissolved organic ligands are thermodynamically stable in seawater. The composition of the ligand pool (in terms of the ratio of soluble to colloidal ligands) in the upper mixed layer (20 - 80 m) shifted towards a greater proportion of soluble ligands after the peak of biomass was reached in the Fe fertilization experiment. Prior to this, the soluble and colloidal ligand fractions were in some sort of equilibrium since dissolved ligand concentrations showed a linear correlation with iron solubility. After the peak of biomass was reached, the same ligand composition as observed below 80 m during the experiment was found in the whole upper mixed layer (20 - 300 m). Organic ligands appeared to have been directly released by bacteria. In contrast to the measurements from the Southern Ocean, measurements made in the Mauritanian upwelling zone showed a significant correlation between indicators of organic matter remineralization (pH, oxygen, and phosphate) and iron solubility in subsurface samples (40 - 80 m). The main increase in iron solubility could be attributed to the remineralization of organic matter. Lab based ultrafiltration experiments on ligand solutions made up in seawater showed that this technique is a powerful tool for separating the particulate and colloidal from the soluble iron fraction. Mass balance calculations showed that a significant portion of the added 55Fe had disappeared from the feed solution before the ultrafiltration was started and yet more disappeared during each cycle of ultrafiltration. Iron was adsorbing onto bottle walls and onto surfaces within the ultrafiltration unit. Future work using trace-metal ultrafiltration needs to recognize that these effects (wall sorption and filter loading) occur and must be taken into account in mass balance calculations. Eisenlöslichkeits- und Ligandenmessungen, welche während dieser Doktorarbeit durchgeführt wurden, zeigten, dass stark bindende organische Liganden die Eisenlöslichkeit und die Verweildauer des Eisens im Meerwasser signifikant erhöhen. Ein mesoskaliges Eisendüngungsexperiment (EIFeX) im Südlichen Ozean zeigte, dass sich im Wasser gelöste organische Liganden aus einer kolloidalen und einer “wirklich” gelösten Phase zusammensetzen, welche beide thermodynamisch stabil sind. Die Zusammensetzung des Ligandenpools in der oberen Mixedlayer (20 - 80 m), welcher sich in einem Gleichgewicht zwischen kolloidal und “wirklich” gelöster Liganden befand, verschob sich zu einem prozentual größeren Anteil “wirklich” gelöster Liganden, nachdem die Biomasseproduktion ihren Höhepunkt erreicht hatte. Das neu eingestellte Gleichgewicht, welches sich nun in der oberen Wassersäule (20 - 300 m) ausgebildet hatte, zeigte eine Ligandenzusammensetzung, die vorher nur unterhalb von 80 m Wassertiefe beobachtet werden konnte. Ebenso konnte nachgewiesen werden, dass die im Meerwasser gelösten organischen Liganden hauptsächlich “absichtlich” von Bakterien in das Meerwasser abgegeben wurden. Ähnliche Messungen, welche in der Mauretanischen-Auftriebs-Zone durchgeführt wurden, zeigten, dass in diesem Meerwasser gelöste organische Liganden hauptsächlich durch den Abbau von organischer Biomasse erzeugt worden sind (lineare Korrelation von pH, Sauerstoff und Phosphat mit der Kapazität von Seewasser f¨ur “wirklich” gelöstes Eisen). Ultrafiltrationsversuche an verschieden Eisenligandenlösungen im Labor zeigten, dass diese Technik sehr gut geeignet ist, um die verschiedenen Größenklassen des Eisen voneinander zu trennen. Später durchgef¨uhrte Massenbilanzrechnungen ergaben, dass ein signifikanter Teil des dazugegebenen 55Fe durch Adsorptionseffekte (Kunststoffwandung und Filtermembran) verloren ging. Diese Nebeneffekte müssen für folgende Ultrafiltrationsexperimente an Spurenmetallen in Betracht gezogen werden, da ansonst Massenbilanzrechnungen nicht erfolgreich durchgeführt werden können.

Three methods to estimate anthropogenic CO2 in the ocean (deltaC* method, TTD (transit time distribution) method and taking the difference of two DIC equilibrium concentrations), which are widely used in observations, were adapted to a coarse resolution (4/3°) ocean general circulation model of the North Atlantic. This is done for testing the methods and comparing them to anthropogenic CO2 modelled directly in this model. Furthermore two methods for modelling anthropogenic CO2 are compared in a climatological forced model run. Modelling anthropogenic CO2 as a passive tracer with a surface flux containing the information of anthropogenic pCO2 perturbation leads to 15% to 20% lower concentrations than the “true” anthropogenic CO2 of the model. This is computed as the difference of DIC concentrations from a model run with realistically prescribed atmospheric pCO2 concentrations minus a model run with a constant preindustrial atmospheric pCO2 concentration, where in both cases a NPZD (nutrient, phytoplankton, zooplankton, detritus) model is coupled to the physical model. For correcting this underestimation by the passive anthropogenic CO2 tracer an improvement to model this tracer is suggested. Adapting a method which uses an age-spectrum (TTD method) or directly modelled water age (difference of two DIC equilibrium concentrations) of a water patch for estimating anthropogenic CO2, leads to concentrations, which are close to the “true” modelled anthropogenic CO2 concentrations. In contrast to that, estimating anthropogenic CO2 by using a method which needs a single chlorofluorocarbon (CFC) derived water age (deltaC* method), leads to high overestimation of the “true” anthropogenic CO2 of the model, especially in the deep ocean. One assumption of the deltaC* method is that anthropogenic CO2 is transported predominantly along isopycnal surfaces. To test this, a sensitivity model run excluding isopycnal mixing was performed. Especially estimating anthropogenic CO2 with the deltaC* method using the output of this model run should fail. However, the results in comparison to the modelled anthropogenic CO2 are differing in nearly the same magnitude as for the model run including isopycnal mixing. The same is the case for the other two methods (TTD method and taking the difference of two DIC equilibrium concentrations) for estimating anthropogenic CO2. Another sensitivity run forced by inter-annual variable surface fluxes was performed in order to determine the influence of inter-annual variability on the estimates of anthropogenic CO2 by using the different methods. In this case the inter-annual variability of anthropogenic CO2 by using the deltaC* method is of the same magnitude as the difference to the “true” modelled anthropogenic CO2 itself. The inter-annual variability of the total amount of anthropogenic CO2 deviates by just about 1% from the climatological reference experiment. Locally variations of up to 10% compared to the climatological mean occur.

Methyl iodide is an atmospheric trace gas and a major source of of atmospheric iodine. The ocaens are the main source of methyl iodide to the atmosphere, but the production pathways of methyl iodide in the ocean are poorly understood. In this thesis the surface seawater concentration of methyl iodide was measured together with air concentrations and the sea-air flux calculated from these measurements. The resulting net flux to the atmosphere was 22 nmol per square meter per day, giving a global oceanic source of 2.9 Gmol methyl iodide per year. Incubation experiments were done in the tropical Atlantic to get more information about the production pathway of methyl iodide in the ocean. The observed production rates were not influenced by filtering or poisoning of the seawater prior to the incubation, but strongly dependent on light. This points to a photochemical production parthway of methyl iodide. Simple model calculations show that the observed photochemical production may be the dominant source of methyl iodide in the ocean.

Die Arbeit beschäftigt sich mit kapillarelektrophoretischen Untersuchungen an Gemischen verschiedener Sulfat- und Nitratlösungen. Hierbei dient die Ramanspektroskopie als Detektor. Nachweisgrenzen, sowie Steigerung der Auflösung durch Einsatz der Kapillarelektrophorese im Vergleich zur herkömmlichen Ramanspektroskopie an Gemischen von Sulfat und Nitrat werden evaluiert.