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Upwelling in the Atlantic sector of the Southern Ocean

Das Projekt "Upwelling in the Atlantic sector of the Southern Ocean" wird vom Umweltbundesamt gefördert und von Universität Bremen, Institut für Umweltphysik, Abteilung Ozeanographie durchgeführt. Upwelling is an important process in setting the characteristic of the mixed layer. Upwelling also provides a pathway for gases, nutrients, and other compounds from the ocean's interior into the mixed layer and ultimately into the atmosphere. Since the upwelling velocities are small, they cannot be measured directly. Recently, Rhein et al. (2010) exploited the helium isotope disequilibria found in the equatorial eastern Atlantic to infer upwelling speeds, upwelling rates, and vertical heat fluxes between the mixed layer and the ocean's interior. The disequilibrium in the mixed layer is caused by upwelling of 3He-enriched water from the interior. The surplus 3He is introduced into the deep ocean by hydrothermal activities.A first survey of historical Helium isotope data in the Antarctic Circumpolar Current (ACC) and the Weddell Sea showed, that the mixed layer is also enriched with 3He, which in summer months is supplied by upwelling of water from below the mixed layer. Although the first estimates of upwelling velocities from the historical data set look promising, the present Helium data lack a sufficient resolution in the upper 200-300m to determine the horizontal and vertical He gradients, necessary for the compilation of the upwelling velocity and of the contribution of diapycnal mixing. Here we propose to take the historical He data, and a new dedicated He data sets to be taken in November 2010 - February 2011 during the POLARSTERN cruise ANT 27/2 and January- February 2012 during POLARSTERN cruise ANT28/3 to calculate upwelling speeds and -rates in the Weddell Sea and the ACC, as well as heat fluxes between the interior and the mixed layer.This proposal is part of the Cluster ' Eddies and Upwelling: Major Factors in the Carbon Budget ofthe Southern Ocean'

ACSYS: Arctic Climate System Study

Das Projekt "ACSYS: Arctic Climate System Study" wird vom Umweltbundesamt gefördert und von Universität Hamburg, Zentrum für Meeres- und Klimaforschung, Institut für Meereskunde (IfM) durchgeführt. Within the international ACSYS project the formation and the export of dense bottom waters from the Barents Sea into the Arctic Ocean and the Norwegian Sea is studied using shipborne and moored instrumentation. The work so far focused on the Storfjord in the southern Svalbard archipelago where earlier measurements have indicated an outflow of brine enriched bottom water that could be traced to the northern Fram Strait to water depths above 2000 m. As part of the summer 1997 experiment three autonomous profiling CTD systems, developed at the University of Kiel, were deployed in the outflow. The only partly successful work with this new instrument lead to a redesign of the system which is currently being implemented.

SP1.1 Dynamische Anreicherungsprozesse von organischer Substanz in der SML

Das Projekt "SP1.1 Dynamische Anreicherungsprozesse von organischer Substanz in der SML" wird vom Umweltbundesamt gefördert und von Helmholtz-Zentrum für Ozeanforschung Kiel (GEOMAR) durchgeführt. Der Oberflächenfilm (SML) ist die oberste dünne Schicht des Ozeans und Teil jeglicher Wechselwirkung zwischen Luft und Meer, wie Gasaustausch, atmosphärische Deposition und Aerosolemission. Die Anreicherung von organischer Materie (OM) in der SML modifiziert die Luft-Meer-Austauschprozesse, aber welche OM-Komponenten selektiv angereichert werden, sowie warum und wann sie dies tun, ist weitgehend unbekannt (Engel et al., 2017). Unsere bisherige Forschung hat gezeigt, dass Biopolymere aus photoautotropher Produktion wichtige Komponenten der SML sind und den Luft-Meer-Austausch beeinflussen, indem sie als Biotenside (Galgani et al., 2016; Engel et al., 2018) und als Quelle primärer organischer Aerosole (Trueblood et al., 2021) wirken. Die Motivation unseres Projektes ist es daher, die dynamischen Anreicherungsprozesse von OM in der SML aufzuklären und zu beschreiben, wobei ein besonderer Schwerpunkt auf der Auflösung der OM-Quellen liegt. Mit unserem Modellierungsansatz ist es das Ziel, unser mechanistisches Verständnis der Zusammenhänge zwischen den Wachstumsbedingungen des Planktons, der Produktion und der Freisetzung von Biomolekülen, einschließlich potentieller Tenside, und der Akkumulation von OM in der SML zu konsolidieren. Eine solche Modellentwicklung wird in hohem Maße von den Ergebnissen und Erkenntnissen der verschiedenen Teilprojekte des BASS-Konsortiums profitieren. Umgekehrt ist es unsere Motivation, ein Modell zu etablieren, das als Synthesewerkzeug für die Interpretation und Integration von Feld-, Mesokosmen- und Labormessungen der OM-Anreicherung in der SML anwendbar wird.Relevanz für die Forschungsgruppe BASS - SP1.1 wird die Quellen, die Menge und die biochemische Zusammensetzung von OM in der SML entschlüsseln und damit wichtige Informationen für alle BASS-Teilprojekte liefern. Der primäre Ursprung von OM im Oberflächenozean ist die photosynthetische Produktion und die wichtigsten biochemischen Komponenten von frisch produzierter OM, d.h. Kohlenhydrate, Aminosäuren und Lipide, unterliegen der mikrobiellen Verarbeitung (SP1.2) und Photoreaktionen innerhalb der SML (SP1.3, SP1.4) und füllen auch den Pool der gelösten organischen Substanz (DOM) auf (SP1.5). Die Modellentwicklung in SP1.1 stellt eine Verbindung zwischen der Produktion von OM und ihrer Anreicherung innerhalb der SML her und zielt darauf ab, die entsprechenden Auswirkungen auf den Luft-Meer-Gasaustausch (SP2.1) zu bestimmen, indem Änderungen des Impulsflusses auf den Ozeanoberflächenschichten (SP2.2) sowie des Auftriebs (SP2.3) berücksichtigt werden. Das vorgeschlagene SML-Submodell wird auf der Grundlage der Ergebnisse aus SP1.4 und SP2.3 verfeinert. Ergebnisse aus den Modellsensitivitätsanalysen werden ergänzende Informationen über oberflächenaktive Eigenschaften verschiedener OM Komponenten und deren Auswirkungen auf Luft-Meer-Austauschprozesse liefern, die innerhalb von BASS ausgewertet werden.

Das Verhalten von Platingruppenelementen während oberkrustaler in situ - Fraktionierung in Magmen der Ferrar Plateaubasaltprovinz, Antarktis

Das Projekt "Das Verhalten von Platingruppenelementen während oberkrustaler in situ - Fraktionierung in Magmen der Ferrar Plateaubasaltprovinz, Antarktis" wird vom Umweltbundesamt gefördert und von Friedrich-Schiller-Universität Jena, Institut für Geowissenschaften durchgeführt. The PGE-patterns of shallow intrusive rocks of the Ferrar Large Igneous Province studied within our previous project are fractionated with respect to primitive mantle, R and Pd being strongly enriched over Ir and Ru (IPGE), correlating with the degree of magma differentiation. While the compatible IPGE are uniformly depleted like Ni and the chalcophile element Cu is uniformly enriched with further differentiation, R and Pd either exhibit enrichment or depletion. The coupled enrichment trend with Cu is unknown from any other volcanic field in MORB-, ocean island- or flood basalt environments. Based on the existing data set on rock chemistry and petrography we are unable to deduce physicochemical differences that may explain the compatible or incompatible behaviour of Pt and Pd during differentiation. Within the project applied here for, we will test the model that internal physicochemical variations in shallow upper crustal magma bodys during in situ - differentiation are responsible for the observed fractionation patterns. Aside from whole-rock analyses we will identify the PGE-bearing mineral phases. These studies will be performed exclusively on already taken samples from sills and the Dufek Intrusion provided by Prof. Woerner, Goettingen, and Prof. Mukasa, Univ. of Michigan, USA and taken by the applicant during the expedition GANOVEX IX in 2005/06. The project is intended to be the initiation of detailed investigations on the PGE internal stratigraphy in the Dufek Intrusion within the framework of two IPY-projects (MESCHEDE et al. 2004, MUKASA 2004

Remote Sensing and Geo informatio n processing in the assessment and monitoring of land degradation and desertification in support of the UNCCD. State of the art and operational perspectives (DESERTSTOP)

Das Projekt "Remote Sensing and Geo informatio n processing in the assessment and monitoring of land degradation and desertification in support of the UNCCD. State of the art and operational perspectives (DESERTSTOP)" wird vom Umweltbundesamt gefördert und von Universität Trier, Fach Umweltfernerkundung und Geoinformatik, Abteilung Fernerkundung durchgeführt. In the past years, the persisting threat of desertification and degradation of natural resources has resulted in a large number of initiatives and research efforts on a global scale, including the United Nations Convention to Combat Desertification. Despite significant progress, knowledge still remains fragmented in many fields, especially with respect to the definition of related indicators or early warning systems. The specific support activity 'Remote Sensing and Geoinformation processing in the assessment and monitoring of land degradation and desertification in support of the UNCCD. State of the art and operational perspectives', intends to serve as a platform to bring together leading scientists working in the fields of remote sensing and geoinformatics with a focus on desertification and land degradation with potential users. A dedicated conference striving for attention on a world wide level will be the core around which various other activities are assembled. Commissioned studies in specific target fields will provide an overview on the state of the art, being complemented through methodological and application studies. Besides taking care of a sound scientific management and logistic organisation of the conference, major efforts will be dedicated towards the international visibility of the event and its results by providing for a high-level dissemination following different pathways (abstract book/CDROM, special issues of scientific journals, printed conference proceedings). A web site will provide further dissemination of the project as well as dynamic elements. Following principles set forth by the Commission under the ENRICH initiative and the quest to strengthen the European Research Area, the project will address renowned scientific experts, and support the participation of experts and stakeholders from third world and developing countries, which are often among the regions most affected from desertification and land degradation.

Die Rolle intermediärer Schwefel-Spezies für Isotopenfraktionierungsprozesse während abiotischer und chemolithoautotropher Sulfidoxidation in natürlichen Systemen

Das Projekt "Die Rolle intermediärer Schwefel-Spezies für Isotopenfraktionierungsprozesse während abiotischer und chemolithoautotropher Sulfidoxidation in natürlichen Systemen" wird vom Umweltbundesamt gefördert und von Helmholtz-Zentrum für Umweltforschung GmbH - UFZ, Department Catchment Hydrology durchgeführt. Sulfur isotope fractionation (34S/32S) has been used since the late 1940s to study the chemical and biological sulfur cycle. While large isotope fractionations during bacterial sulfate reduction were used successfully to interpret, e.g., accumulation of sulfate in ancient oceans or the evolution of early life, much less is known about fractionation during sulfide oxidation. The fractionation between the two end-members sulfide and sulfate is commonly much smaller and inconsistencies exist whether substrate or product are enriched. These inconsistencies are explained by a lack of knowledge on oxidation pathways and rates as well as intermediate sulfur species, such as elemental sulfur, polysulfides, thiosulfate, sulfite, or metalloid-sulfide complexes (e.g. thioarsenates), potentially acting as 34S sinks.In the proposed project, we will develop a method for sulfur species-selective isotope analysis based on separation by preparative chromatography. Separation of Sn2- and S0 will be achieved after derivatization with methyl triflate on a C18 column, separation of the other sulfur species in an alkaline eluent on an AS16 column. Sulfur in the collected fractions will be extracted directly with activated copper chips (Sn2-, S0), or precipitated as ZnS (S2-) or BaSO4 and analyzed by routine methods as SO2. Results of this species-selective approach will be compared to those from previous techniques of end-member pool determinations and sequential precipitations.The method will be applied to sulfide oxidation profiles at neutral to alkaline hot springs at Yellowstone National Park, USA, where we detected intermediate sulfur species as important species. Determining 34S/32S only in sulfide and sulfate, our previous study has shown different fractionation patterns for two hot spring drainages with sulfide oxidation profiles that seemed similar from a geochemical perspective. The reasons for the different isotopic trends are unclear. In the present project, we will differentiate species-selective abiotic versus biotic fractionation using on-site incubation experiments with the chemolithotrophic sulfur-oxidizing bacteria Thermocrinis ruber as model organism. For selected samples, we will test whether 33S and 36S further elucidate species-selective sulfide oxidation patterns. We expect that lower source sulfide concentrations increase elemental sulfur disproportionation, thus increase redox cycling and isotope fractionation. We also expect that the larger the concentration of intermediate sulfur species, including thioarsenates, the larger the isotope fractionation. Following fractionation in species-selective pools, we will be able to clarify previously reported inconsistencies of 34S enrichment in substrate or product, elucidate sulfide oxidation pathways and rates, and reveal details about sulfur metabolism. Our new methodology and field-based data will be a basis for more consistent studies on sulfide oxidation in the future.

The Alnus-problem and the exceedance of critical loads for nitrogen in the Alps

Das Projekt "The Alnus-problem and the exceedance of critical loads for nitrogen in the Alps" wird vom Umweltbundesamt gefördert und von Universität Basel, Botanisches Institut, Abteilung Pflanzenökologie durchgeführt. Large areas of abandoned pasture land in the Alps are currently encroached by shrub at a breathtaking speed, with green alder (Alnus viridis) playing the most prominent role. Dense Alnus thickets reduce plant diversity in former species-rich upper montane grassland, prevent natural forest succession, change the water relations at the landscape scale by reducing runoff, contribute through symbiotic N2 fixation substantially to eutrophication by leaching nitrate to the river system and exert risks to local drinking water springs. Paradoxically, this conversion into species-poor, nitrogen enriching and releasing Alnus thickets occurs in mountain regions considered particularly rich in biodiversity and essential for the continuing provision of many ecosystem goods and services, particularly for clean and plentiful water. Except from local sources, critical loads for nitrogen by atmospheric deposition are only rarely exceeded in these high elevation regions. The project ALNEX is designed (1) to quantify the water quality impact of Alnus by measuring the nitrogen pools and fluxes from single alder shrub to catchment-wide landscapes, (2) to elaborate land management guidelines towards preserving of open, centuries-old pasture land and (3) to assess the policy implications in a critical load and biodiversity context.

Alpine ecosystems in a changing climate: experimental CO2 enrichment and warming

Das Projekt "Alpine ecosystems in a changing climate: experimental CO2 enrichment and warming" wird vom Umweltbundesamt gefördert und von Eidgenössische Forschungsanstalt für Wald, Schnee und Landschaft, Eidgenössisches Institut für Schnee- und Lawinenforschung durchgeführt. Within the next decades, a two-fold increase in CO2 concentrations and a rise in temperatures by 1.4 to 5.8 C can be expected (IPCC 2001). Temperature changes in the past decades have been more pronounced in alpine and high-latitude ecosystems than in most other regions of the world (IPCC 2001). Alpine ecosystems are particularly sensitive to environmental changes because they represent a boundary ecosystem that is subjected to extreme climatic conditions. Since temperature and CO2 are key factors that regulate many ecosystem processes, the changing climate will have large effects on vegetation and soils. In this proposal, we intend to analyze effects of manipulated temperature and CO2 in alpine ecosystems at treeline. Our major aim is to study potential feedbacks between climate change, plant growth and ecosystem processes. Although the European Alps are certainly the most studied of all high mountain ranges in the world, predictions of potential impacts of climate change on ecosystems are mainly based on modeling studies or on observations of inter-annual and spatial variability. There are only a few attempts to manipulate climatic conditions in situ. A combination of an experimental increase in CO2 and temperatures in the Alps has not been carried out before. In the proposed project, we enrich experimental plots with CO2 using a FACE approach and increase temperatures with heating cables at the soil surface. The experiment has already been set up at a treeline site near Davos. The CO2 enrichment was started in 2001 and increased CO2 concentration to 550 ppm. During the 6th year of operation, as part of a co-operation with a French team, a parallel soil warming treatment was installed on half of the test plots in a crossed design with the CO2 treatment, which successfully increases soil and air temperatures by 3K. We aim at investigating the interactive effects of elevated CO2 and warming on plant growth, biodiversity and ecosystem responses. Our proposed study addresses the following key questions: Will effects of elevated CO2 persist in the longer term and will these effects change under increased temperatures? How does biodiversity and the dominant vegetation, i.e. dwarf shrubs vs. trees, react to elevated CO2 and warming? How does elevated CO2 and warming affect key ecosystem functions such as nutrient uptake and decomposition? The focus will be on the two major tree species European larch and Mountain pine and on the dominant dwarf shrub species, especially Vaccinium myrtillus and V. uliginosum. Measurements of plant growth will include length increment, productivity, phenology and reproduction. Changes in biodiversity will be monitored

Interactive effects of global warming and nutrient enrichment on litter decomposition in freshwater marshes

Das Projekt "Interactive effects of global warming and nutrient enrichment on litter decomposition in freshwater marshes" wird vom Umweltbundesamt gefördert und von Eawag - Das Wasserforschungsinstitut des ETH-Bereichs durchgeführt. Many human activities have repercussions that are profoundly altering natural ecosystems at large-scales. The physical interference by humans with the climate systems has been intensively studied and has become increasingly clear. Significant progress has also been made in assessing range shifts of species and various other ecological responses such as altered species interactions. However, the consequences for ecosystem functioning and possible feedbacks on climate are still poorly understood. This is particularly true for aquatic ecosystems. In addition, information is exceedingly scant on the interactive effects of multiple environmental factors that are changing simultaneously. The proposed project builds on our previous experiments in a freshwater marsh to assess the combined effects of elevated temperature and nutrient loading on litter decomposition, a critical component of carbon cycling at the local and global scale in a variety of ecosystems. The general hypothesis is that impacts of elevated temperature, nutrient loading and the interaction of both are not readily predictable from current theory or through simple laboratory experiments, and that the magnitude of effects is such that important ramifications for elemental flows both within wetlands and across their boundaries are likely to result. I propose testing at this stage a series of specific hypotheses derived from our previous findings and relating to the effects of temperature and nutrients on decomposition. The focus will be on three priorities: (1) testing whether the lack of stimulation of litter decomposition by nitrogen enrichment that we observed is due to the limiting role of phosphorus in the marsh; (2) testing whether a shift in life-history patterns of specific detritivore taxa is responsible for the observed dramatic acceleration of litter decomposition in spring under simulated global warming; and (3) assessing whether the observed lack of effects by elevated temperature and nutrient loading on stem litter decomposition may be related to changes in O2 regimes during long-term operation of enclosures. The backbone of the proposed experiments to address these questions is a unique manipulative field experiment in enclosures installed in a littoral marsh dominated by Phragmites australis. Enclosures are heated to 4 C above ambient water temperature or enriched with Ca(NO3)2 or both. The experiment is set up as a randomized block design (N = 4) with two factors (temperature and nitrate enrichment), each with two levels. An open-marsh control is also included. The first two questions will be addressed in combined field enclosure and laboratory microcosm experiments, while the third question will be addressed in a field enclosure experiment only. The processes considered in different experiments include litter decomposition, nutrient immobilization, microbial respiration and productivity, enzymatic activity, and various measures of detritivore performance.

AsFeP0 - A model concept for in situ investigation or arsenic and phosphate adsorption to predefined iron minerals and to characterize transformation processes of iron minerals

Das Projekt "AsFeP0 - A model concept for in situ investigation or arsenic and phosphate adsorption to predefined iron minerals and to characterize transformation processes of iron minerals" wird vom Umweltbundesamt gefördert und von Eidgenössische Anstalt für Wasserversorgung, Abwasserreinigung und Gewässerschutz, Abteilung Wasserressourcen und Trinkwasser durchgeführt. Shallow groundwater of the huge deltaic systems of Asia like the Red River Delta in Vietnam is often enriched in inorganic arsenic (As), threatening the health of millions of residents. The massive abstraction of groundwater in these areas locally causes an irreversible mixing of arsenic-free groundwater resources with arsenic-rich groundwater. Increased concentrations of competitive anions, especially phosphate (PO43-), decrease the immobilization capacity of the sediments. During transport, the mobility of dissolved As in local aquifers is strongly influenced by adsorption to sedimentary and ubiquitously occurring iron(oxyhydr)oxides. Additionally, arsenic-rich groundwater is often enriched in reduced iron (Fe2+) as well, which is capable to react with iron(oxyhydr)oxides, thereby inducing mineral transformations. Such transformations permanently affect the arsenic adsorption and immobilization capacity of the sediments.Within the scope of this research project, the underlying mechanisms related to As transport and the resulting threat to arsenic-free groundwater resources will be characterized in cooperation with the Swiss Federal Institute of Aquatic Science and Technology (Eawag). The research concept aims at assessing the complex interactions within the arsenic-iron-phosphate-system under field conditions at a study site next to the Red River. First, filtration experiments using local groundwater enriched in As and PO43- will be used to determine the As adsorption capacity of different and previously geochemically characterized iron(oxyhydr)oxides. In a second step, sample carrier containing As loaded iron(oxyhydr)oxides will be introduced into surface near aquifer parts of the study site (via existing groundwater monitoring wells). These samples will be exposed to local groundwater characterized by increased As, Fe2+ and PO43- concentrations for the following nine months. Using the in situ exposition of predefined iron(oxyhydr)oxides, it will be possible to distinguish potential mineral transformations and their influences on the As immobilization capacity of the respective iron(oxyhydr)oxides. By combining the results and outcomes of the field experiments, new and important conclusions regarding the mobility of As can be drawn. The data can be used to create a hydrochemical transport model describing reactive As transport within the investigation area. In addition, the results of the in situ exposition experiments will allow to draw conclusions in respective to the long term As immobilization capacity of different iron(oxyhydr)oxides, which is an essential information regarding in situ decontamination techniques.

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