In the Earth, the dynamo action is strongly linked to core freezing. There is a solid inner core, the growth of which provides a buoyancy flux that drives the dynamo. The buoyancy in this case derives from a difference in composition between the solid inner core and the fluid outer core. In planetary bodies smaller than the Earth, however, this core differentiation process may differ - Fe may precipitate at the core-mantle boundary (CMB) rather than in the center and may fall as iron snow and initially remelt with greater depth. A chemical stable sedimentation zone develops that comprises with time the entire core - at that time a solid inner core starts to grow. The dynamics of this system is not well understood and also whether it can generate a magnetic field or not. The Jovian moon Ganymede, which shows a present-day magnetic dipole field, is a candidate for which such a scenario has been suggested. We plan to study this Fe-snow regime with both a numerical and experimental approach. In the numerical study, we use a 2D/3D thermo-chemical convection model that considers crystallization and sinking of iron crystals together with the dynamics of the liquid core phase (for the 3D case the influence of the rotation of the Fe snow process is further studied).The numerical calculations will be complemented by two series of experiments: (1) investigations in metal alloys by means of X-ray radioscopy, and (2) measurements in transparent analogues by optical techniques. The experiments will examine typical features of the iron snow regime. On the one hand they will serve as a tool to validate the numerical approach and on the other hand they will yield important insight into sub-processes of the iron snow regime, which cannot be accessed within the numerical approach due to their complexity.
Aktuelle wissenschaftliche Studien legen nahe, dass die aktuelle Erderwärmung durch Treibhausgasemissionen hervorgerufen wird, die vom Menschen verursacht sind. Um gegen diese Entwicklung geeignete Maßnahmen ergreifen zu können bzw. um zu überprüfen, ob solche Maßnahmen von Erfolg gekrönt sind, ist es notwendig, die Schadstoffkonzentrationen inklusive der zugehörigen Emissionsquellen genau zu kennen. Diese Informationen sind bisher jedoch sehr lückenhaft und beruhen auf sogenannten 'bottom-up' Berechnungen. Da diese Kalkulationen nicht auf direkten Messungen beruhen, weisen sie große Ungenauigkeiten auf und sind außerdem nicht in der Lage, bisher unbekannte Emissionsquellen zu identifizieren. In dem hier vorgestellten Projekt soll ein mesoskaliges Netzwerk für die Überwachung von Luftschadstoffen wie CO2, CH4, CO, NO2 und O3 aufgebaut werden, das auf dem neuartigen Konzept der differentiellen Säulenmessung beruht. Bei diesem Ansatz wird die Differenz zwischen den Luftsäulen luv- und leewärts einer Stadt gebildet. Diese Differenz ist proportional zu den emittierten Schadstoffen und somit eine Maßzahl für die Emissionen, welche in der Stadt generiert werden.Mithilfe dieser Methode wird es in Zukunft möglich sein, städtische Emissionen über lange Zeiträume hinweg zu überwachen. Damit können neue Informationen über die Generierung und Umverteilung von Luftschadstoffen gewonnen werden. Wir werden u.a. folgende zentrale Fragen beantworten: Wie verhält sich der tatsächliche Trend der CO2, CH4 und NO2 Emissionen in München über mehrere Jahre? Wo sind die Emissions-Hotspots? Wie akkurat sind die bisherigen 'bottom-up' Abschätzungen? Wie effektiv sind die Maßnahmen zur Emissionsreduzierung tatsächlich? Sind vor allem für Methan weitere Maßnahmen zur Reduzierung der Emissionen notwendig? Zu diesem Zweck werden wir ein vollautomatisiertes Messnetzwerk aufbauen und passende Methoden zur Modellierung entwickeln, welche u.a. auf STILT (Stochastic Time-Inverted Lagrangian Transport) und CFD (Computational Fluid Dynamics) basieren. Mithilfe der Modellierungsresultate werden wir eine Strategie entwerfen, wie städtische Netzwerke zur Überwachung von Luftschadstoffen aufgebaut werden müssen, um repräsentative Ergebnisse zu erhalten. Außerdem können mit den so gewonnenen städtischen Emissionszahlen z.B. dem Stadtreferat, den Stadtwerken München oder der Bayerischen Staatsregierung Möglichkeiten zur Beurteilung der Effektivität der angewandten Klimaschutzmaßnahmen an die Hand gegeben werden. Das hier vorgestellte Messnetzwerk dient somit als Prototyp, um die grundlegenden Fragen zum Aufbau eines solchen Sensornetzwerks zu klären, damit objektive Aussagen zu städtischen Emissionen möglich werden. Dieses Projekt ist weltweit einmalig und wird zukunftsweisende Ergebnisse liefern.
Outbreaks of foodborne illness linked to consumptions of fresh, or partially processed, agricultural products are a growing concern in industrialized and developing countries. The incidence of human pathogens on fresh fruits and vegetables is often related to the use of recycled wastewaster in surface irrigation as well as high amounts of animal manure in agricultural management practice. Thereby the soil inhabiting fauna plays an important role in the transport and dissemination of microorganisms. The focus of the proposed project is on nematodes, well known vectors for bacteria and viruses in soil. The major goals are to: (1) survey human pathogens in soil and on/in free-living and plant parasitic nematodes in agriculture field sites irrigated with recycled wastewater or fertilized with fresh animal manure in Israel and the Palestinian Authority, (2) assess the function of nematodes as vectors in transmitting bacteria from microbial hot spots to plants, and (3) localize bacteria on and/or within the nematode and identify bacterial factors required for survival in the nematode host. Understanding the mechanisms involved in dissemination of human pathogens by nematodes will enhance the ability to develop practical means to minimize contamination of fresh produce and increase safety in food production.
Background and Objectives: The project area is located in the Ashanti Region of Ghana / West Africa in the transition zone of the moist semideciduous forest and tropical savannah zone. Main land use in this region is subsistence agriculture with large fallow areas. As an alternative land-use, forest plantations are under development by the Ghanaian wood processing company DuPaul Wood Treatment Ltd. Labourers from the surrounding villages are employed as permanent or casual plantation workers. Within three forest plantation projects of approximately 6,000 ha, DuPaul offers an area of 164 ha (referred to as Papasi Plantation) - which is mainly planted with Teak (Tectona grandis) - for research purposes. In return, the company expects consultations to improve the management for sustainable timber and pole production with exotic and native tree species. Results: In a first research approach, the Papasi Plantation was assessed in terms of vegetation classification, timber resources (in qualitative and quantitative terms) and soil and site conditions. A permanent sampling plot system was established to enable long-term monitoring of stand dynamics including observation of stand response to silvicultural treatments. Site conditions are ideally suited for Teak and some stands show exceptionally good growth performances. However, poor weed management and a lack of fire control and silvicultural management led to high mortality and poor growth performance of some stands, resulting in relative low overall growth averages. In a second step, a social baseline study was carried out in the surrounding villages and identified landowner conflicts between some villagers and DuPaul, which could be one reason for the fire damages. However, the study also revealed a general interest for collaboration in agroforestry on DuPaul land on both sides. Thirdly, a silvicultural management concept was elaborated and an improved integration of the rural population into DuPaul's forest plantation projects is already initiated. If landowner conflicts can be solved, the development of forest plantations can contribute significantly to the economic income of rural households while environmental benefits provide long-term opportunities for sustainable development of the region. Funding: GTZ supported PPP-Measure, Foundation
The present-day configuration of Indonesia and SE Asia is the results of a long history of tectonic movements, volcanisms and global eustatic sea-level changes. Not indifferent to these dynamics, fauna and flora have been evolving and dispersing following a complicate pattern of continent-sea changes to form what are today defined as Sundaland and Wallacea biogeographical regions. The modern intraannual climate of Indonesia is generally described as tropical, seasonally wet with seasonal reversals of prevailing low-level winds (Asian-Australian monsoon). However at the interannual scale a range of influences operating over varying time scales affect the local climate in respect of temporal and spatial distribution of rainfall. Vegetation generally reflects climate and to simplify it is possible to distinguish three main ecological elements in the flora of Malaysia: everwet tropical, seasonally dry tropical (monsoon) and montane. Within those major ecological groups, a wide range of specific local conditions caused a complex biogeography which has and still attract the attention of botanists and biogeographers worldwide. Being one of the richest regions in the Worlds in terms of species endemism and biodiversity, Indonesia has recently gone through intensive transformation of previously rural/natural lands for intensive agriculture (oil palm, rubber, cocoa plantations and rice fields). Climate change represents an additional stress. Projected climate changes in the region include strengthening of monsoon circulation and increase in the frequency and magnitude of extreme rainfall and drought events. The ecological consequences of these scenarios are hard to predict. Within the context of sustainable management of conservation areas and agro-landscapes, Holocene palaeoecological and palynological studies provide a valuable contribution by showing how the natural vegetation present at the location has changed as a consequence of climate variability in the long-term (e.g. the Mid-Holocene moisture maximum, the modern ENSO onset, Little Ice Age etc.). The final aim of my PhD research is to compare the Holocene history of Jambi province and Central Sulawesi. In particular: - Reconstructing past vegetation, plant diversity and climate dynamics in the two study areas Jambi (Sumatra) and Lore Lindu National Park (Sulawesi) - Comparing the ecological responses of lowland monsoon swampy rainforest (Sumatra) and everwet montane rainforests (Sulawesi) to environmental variability (vulnerability/resilience) - Investigating the history of human impact on the landscape (shifting cultivation, slash and burn, crop cultivation, rubber and palm oil plantation) - Assessing the impact and role of droughts (El Niño) and fires - Adding a historical perspective to the evaluation of current and future changes.
Irrigation in the Yanqi Basin, Sinkiang, China has led to water table rise and soil salination. A model is used to assess management options. These include more irrigation with groundwater, water saving irrigation techniques and others. The model relies on input data from remote sensing.The Yanqi Basin is located in the north-western Chinese province of Xinjiang.This agriculturally highly productive region is heavily irrigated with water drawn from the Kaidu River. The Kaidu River itself is mainly fed by snow and glacier melt from the Tian Mountain surrounding the basin. A very poor drainage system and an overexploitation of surface water have lead to a series of environmental problems: 1. Seepage water under irrigated fields has raised the groundwater table during the last years, causing strongly increased groundwater evaporation. The salt dissolved in the groundwater accumulates at the soil surface as the groundwater evaporates. This soil salinization leads to degradation of vegetation as well as to a loss of arable farmland. 2. The runoff from the Bostan Lake to the downstream Corridor is limited since large amount of water is used for irrigation in the Yanqi Basin. Nowadays, the runoff is maintained by pumping water from the lake to the river. The environmental and ecological system is facing a serious threat.In order to improve the situation in the Yanqi Basin, a jointly funded cooperation has been set up by the Institute of Environmental Engineering, Swiss Federal Institute of Technology (ETH) , China Institute of Geological and Environmental Monitoring (CIGEM) and Xinjiang Agricultural University. The situation could in principle be improved by using groundwater for irrigation, thus lowering the groundwater table and saving unproductive evaporation. However, this is associated with higher cost as groundwater has to be pumped. The major decision variable to steer the system into a desirable state is thus the ratio of irrigation water pumped from the aquifer and irrigation water drawn from the river. The basis to evaluate the ideal ratio between river and groundwater - applied to irrigation - will be a groundwater model combined with models describing the processes of the unsaturated zone. The project will focus on the following aspects of research: (...)
Organic matter (OM) composition and dynamic in subsoils is thought to be significantly different from those in surface soils. This has been suggested by increasing apparent 14C ages of bulk soil OM with depth suggesting that the amount of fresh, more easily degradable components is declining. Compositional changes have been inferred from declining ä13C values and C/N ratios indicative for stronger OM transformation. Beside these bulk OM data more specific results on OM composition and preservation mechanisms are very limited but modelling studies and results from incubation experiments suggest the presence and mineralization of younger, 'reactive carbon pool in subsoils. Less refractory OM components may be protected against degradation by interaction with soil mineral particles and within aggregates as suggested by the very limited number of more specific OM analysis e.g., identification of organic compound in soil fractions. The objective of this project is to characterize the composition, transformation, stabilization and bioavailability of OM in subsurface horizons on the molecular level: 1) major sources and compositional changes with depth will be identified by analysis of different lipid compound classes in surface and subsoil horizons, 2) the origin and stabilization of 'reactive OM will be revealed by lipid distributions and 14C values of soil fractions and of selected plant-specific lipids, and 3) organic substrates metabolized by microbial communities in subsoils are identified by distributional and 14C analysis of microbial membrane lipids. Besides detailed analyses of three soil profiles at the subsoil observatory site (Grinderwald), information on regional variability will be gained from analyses of soil profiles at sites with different parent material.
Introduction: In Malaysia, excessive nutrients from livestock waste management systems are currently released to the environment. Particularly, large amounts of manure from intensive pig production areas are being excreted daily and are not being fully utilised. Alternatively, the excess manure can be applied as an organic fertiliser source in neighbouring cropping systems on the small landholdings of the pig farms to improve soil fertility so that its nutrients will be available for crop uptake instead of being discharged into water streams. Thus, there is a need for better tools to analyse the present situation, to evaluate and monitor alternative livestock production systems and manure management scenarios, and to support farmers in the proper management of manure and fertiliser application. Such tools are essential to quantify, and assess nutrient fluxes, manure quality and content, manure storage and application rate to the land as well as its environmental effects. Several computer models of animal waste management systems to assist producers and authorities are now available. However, it is felt that more development is needed to adopt such models to the humid tropics and conditions of Malaysia and other developing countries in the region. Objectives: The aim is to develop a novel model to evaluate nutrient emission scenarios and the impact of livestock waste at the landscape or regional level in humid tropics. The study will link and improve existing models to evaluate emission of N to the atmosphere, and leaching of nutrients to groundwater and surface water. The simulation outputs of the models will be integrated with a GIS spatial analysis to model the distribution of nutrient emission, leaching and appropriate manure application on neighbouring crop lands and as an information and decision support tool for the relevant users.
Die Relevanz von Unsicherheitsanalysen in der Hydrogeology ist vergleichsweise groß aufgrund der Tatsache, dass Aquifereigenschaften oft sehr heterogen sind und meist nur wenige in-situ Daten zu deren Charakterisierung zu Verfügung stehen. Die Bayes'sche Statistik ist hervorragend geeignet, um solche Analysen durch zu führen. Verglichen mit klassicher, frequentistischer Statistik lassen sich Unsicherheiten deutlich einfacher modellieren, können Wahrscheinlichkeitsaussagen auch für Einzelfälle getroffen werden und Hintergrundwissen von ex-situ Messungen konsistent mittels der A-priori-Verteilung repräsentiert werden. In der Praxis werden allerdings sowohl Unsicherheitsanalyse wie auch Aquifercharakterisierung nur selten mit Bayes'schen Methoden durchgeführt. Der wahrscheinlich wichtigste Hinderungsgrund ist dabei die Schwierigkeit die A-priori-Verteilung zu bestimmen, welche die (Un)sicherheit bzgl. der Aquifereigenschaften ausdrückt bevor in-situ Daten berücksichtigt wurden. In diesem Projekt werde ich dieses Problem angehen, in dem ich (i) einen Arbeitsablauf zur Bestimmung der A-priori-Verteilung ausarbeite und (ii) den Einfluss solch einer Verteilung untersuche. Im ersten Teil werde ich Gebrauch machen von dem hierarchischem Bayes'schen Modell zur Bestimmung von A-priori-Verteilungen, welches in einer Zusammenarbeit zwischen der Arbeitsgruppe von Prof. Yoram Rubin und mir entwickelt wurde. Um dieses Modell mit einem umfangreichen und repräsentativen Datensatz zu versorgen, werde ich es mit einer etablierten Datenbank hydrogeologischer Messungen koppeln. Dadurch wird es möglich informative A-priori-Verteilungen zu bestimmen, welche das Hintergrundwissen von ex-situ Messungen repräsentieren. Im zweiten Teil werde ich den Einfluss dieser informativen A-priori-Verteilungen auf Fragen der Unsicherheitsreduktion und des resultierenden Datenwertes untersuchen. Dazu werde ich eine Reihe von klassischen Meß- und Interpretationsverfahren mit einem Bayes'schen Aquivalent vergleichen. Dabei wird vor allem die Frage des relativen Datenwertes im Mittelpunkt stehen. Relativ bezieht sich hierbei auf den Einfluss von in-situ Daten verglichen mit den ex-situ Daten, welche in der A-priori-Verteilung enthalten sind. Die Ergebnisse dieses Projektes werden demnach helfen einen konsistenten und reproduzierbaren Arbeitsablauf zur Ableitung hydrogeologischer A-priori-Verteilungen zu etablieren sowie deren Einfluss auf Fragen der Unsicherheitsreduktion und des relativen Datenwertes von in-situ Messungen zu bestimmen. Des Weiteren werden die Ergebnisse dazu dienen die Vorteile sowie mögliche Nachteile Bayes'scher Methoden für die hydrogeologische Unsicherheitsanalyse zu verstehen. Dadurch werden die Herausforderungen klar, die zu überwinden sind, um Bayes'sche Statistik zu einem allgemein genutztem Standard für hydrogeologische Unsicherheitsanalysen werden zu lassen.
Bamboos (Poaceae) are widespread in tropical and subtropical forests. Particularly in Asia, bamboos are cultivated by smallholders and increasingly in large plantations. In contrast to trees, reliable assessments of water use characteristics for bamboo are very scarce. Recently we tested a set of methods for assessing bamboo water use and obtained first results. Objectives of the proposed project are (1) to further test and develop the methods, (2) to compare the water use of different bamboo species, (3) to analyze the water use to bamboo size relationship across species, and (4) to assess effects of bamboo culm density on the stand-level transpiration. The study shall be conducted in South China where bamboos are very abundant. It is planned to work in a common garden (method testing), a botanical garden (species comparison, water use to size relationship), and on-farm (effects of culm density). Method testing will include a variety of approaches (thermal dissipation probes, stem heat balance, deuterium tracing and gravimetry), whereas subsequent steps will be based on thermal methods. The results may contribute to an improved understanding of bamboo water use characteristics and a more appropriate management of bamboo with respect to water resources.
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