Im Rahmen des gemeinsames Bund/Länder-Messprogramm für die Nord- und Ostsee + weitere Überwachungsprogramme wurde der Parameter "Druck " im Meerwasser bestimmt.
Im Rahmen des gemeinsames Bund/Länder-Messprogramm für die Nord- und Ostsee + weitere Überwachungsprogramme wurde der Parameter "Druck " im Meerwasser bestimmt.
Im Rahmen des gemeinsames Bund/Länder-Messprogramm für die Nord- und Ostsee + weitere Überwachungsprogramme wurde der Parameter "Druck " im Meerwasser bestimmt.
Im Rahmen des gemeinsames Bund/Länder-Messprogramm für die Nord- und Ostsee + weitere Überwachungsprogramme wurde der Parameter "Druck " im Meerwasser bestimmt.
Im Rahmen des gemeinsames Bund/Länder-Messprogramm für die Nord- und Ostsee + weitere Überwachungsprogramme wurde der Parameter "Druck " im Meerwasser bestimmt.
Im Rahmen des gemeinsames Bund/Länder-Messprogramm für die Nord- und Ostsee + weitere Überwachungsprogramme wurde der Parameter "Druck " im Meerwasser bestimmt.
Im Rahmen des gemeinsames Bund/Länder-Messprogramm für die Nord- und Ostsee + weitere Überwachungsprogramme wurde der Parameter "Druck " im Meerwasser bestimmt.
Das Projekt "B 5.1: Fate of agrochemicals in integrated farming systems in Son-La province, Northern Vietnam" wird vom Umweltbundesamt gefördert und von Universität Hohenheim, Institut für Bodenkunde und Standortslehre, Fachgebiet Biogeophysik durchgeführt. In Son La province, Northern Vietnam, many irrigated farming systems include ponds in which small-scale farmers raise fish to produce additional food and income. The main field crops in this area are paddy rice and maize. Often, irrigation water is first used in paddy fields, before it flows to the fishponds. Because farmers regularly apply considerable amounts of agrochemicals, mainly insecticides, to field crops fish production suffers. Moreover, agrochemicals may enter the human food chain. Subproject B5.1 will study the fate of agrochemicals applied in two subcatchments near Yen Chau, Son La province. Investigations will be carried out in close collaboration with A1.3, B4.1, C4.1, D5.2, and G1.2. In the two subcatchments, fishponds have been investigated by D5.1 since 2003. We will carry out a survey of the subcatchments with special emphasis on the water distribution systems (fields, ponds, canals, brooks). The data will be linked to the GIS (Geographical Information System) set up by B4.1. In one subcatchment, B5.1 will install a weather station as well as five TDR (time do-main reflectometry) probes and tensiometers. Water flow through the system will be recorded by means of water meters and V-shaped (Thompson) weirs equipped with automatic pressure sensors. Soil and water samples from selected fields sites, pond inflows, and ponds will be regularly screened for agrochemicals using the procedure developed by B2.1 (Ciglasch et al., 2005; see below). Soil and sediment characteristics that determine water regime and soil-agrochemical interaction, e.g. texture, organic carbon content, hydraulic conductivity, partitioning coefficients, and half-life times will be measured in laboratory and field experiments in cooperation with B4.1. In preparation for the next phase, discharge will be assessed and agrochemical concentrations monitored in the main catchment.
Das Projekt "The role of turgor in rain-cracking of sweet cherry fruit" wird vom Umweltbundesamt gefördert und von Leibniz Universität Hannover, Institut für Biologische Produktionssysteme, Fachgebiet Obstbau durchgeführt. Rain-cracking limits the production of many soft and fleshy fruit including sweet cherries world wide. Cracking is thought to result from increased water uptake through surface and pedicel. Water uptake increases fruit volume, and hence, turgor of cells (Pcell) and the pressure inside the fruit (Pfruit) and subjects the skin to tangential stress and hence, strain. When the strain exceeds the limits of extensibility the fruit cracks. This hypothesis is referred to as the Pfruit driven strain cracking. Based on this hypothesis cracking is related to two independent groups of factors: (1) water transport characteristics and (2) the intrinsic cracking susceptibility of the fruit defined as the amount of cracking per unit water uptake. The intrinsic cracking susceptibility thus reflects the mechanical constitution of the fruit. Most studies focussed on water transport through the fruit surface (factors 1), but only little information is available on the mechanical constitution (i.e., Pfruit and Pcell, tensile properties such as fracture strain, fracture pressure and modulus of elasticity of the exocarp; factors 2). The few published estimates of Pfruit in sweet cherry are all obtained indirectly (calculated from fruit water potential and osmotic potentials of juice extracts) and unrealistically high. They exceed those measured by pressure probe techniques in mature grape berry by several orders of magnitude. The objective of the proposed project is to test the hypothesis of the Pfruit driven strain cracking. Initially we will focus on establishing systems of widely differing intrinsic cracking susceptibility by varying species (sweet and sour cherry, Ribes and Vaccinium berries, plum, tomato), genotype (within sweet cherry), stage of development and temperature. These systems will then be used for testing the hypothesis of Pfruit driven strain cracking. We will quantify Pfruit und Pcell by pressure probe techniques and compression tests and the mechanical properties of the exocarp using biaxial tensile tests. When the presence of high Pfruit and Pcell is confirmed by direct measurements, subsequent studies will focus on the mode of failure of the exocarp (fracture along vs. across cell walls) and the relationship between failure thresholds and morphometric characteristics of the exocarp. However, when Pfruit und Pcell are low, the hypothesis of Pfruit driven strain cracking must be rejected and the mechanistic basis for low pressures (presence of apoplastic solutes) clarified on a temporal (in the course of development) and a spatial scale (exocarp vs. mesocarp). We focus on sweet cherry, because detailed information on this species and experience in extending the short harvest period is available. Where appropriate, other cracking susceptible species (sour cherry, plum, Vaccinium, Ribes, tomato) will be included to further extend the experimental period and to maximize the range in intrinsic cracking susceptibility.
Das Projekt "Soil-gas transport-processes as key factors for methane oxidation in soils" wird vom Umweltbundesamt gefördert und von Universität Freiburg, Institut für Geo- und Umweltnaturwissenschaften, Professur für Bodenökologie durchgeführt. Methane (CH4) is a major greenhouse gas of which the atmospheric concentration has more than doubled since pre-industrial times. Soils can act as both, source and sink for atmospheric CH4, while upland forest soils generally act as CH4 consumers. Oxidation rates depend on factors influenced by the climate like soil temperature and soil moisture but also on soil properties like soil structure, texture and chemical properties. Many of these parameters directly influence soil aeration. CH4 oxidation in soils seems to be controlled by the supply with atmospheric CH4, and thus soil aeration is a key factor. We aim to investigate the importance of soil-gas transport-processes for CH4 oxidation in forest soils from the variability the intra-site level, down to small-scale (0.1 m), using new approaches of field measurements. Further we will investigate the temporal evolution of soil CH4 consumption and the influence of environmental factors during the season. Based on previous results, we hypothesize that turbulence-driven pressure-pumping modifies the transport of CH4 into the soil, and thus, also CH4 consumption. To improve the understanding of horizontal patterns of CH4 oxidation we want to integrate the vertical dimension on the different scales using an enhanced gradient flux method. To overcome the constraints of the classical gradient method we will apply gas-diffusivity measurements in-situ using tracer gases and Finite-Element-Modeling. Similar to the geophysical technique of Electrical Resistivity Tomography we want to develop a Gas Diffusivity Tomography. This will allow to derive the three-dimensional distribution of soil gas diffusivity and methane oxidation.