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Transport of EINP through soil affected by the dynamics of infiltration flux and particle properties

Das Projekt "Transport of EINP through soil affected by the dynamics of infiltration flux and particle properties" wird vom Umweltbundesamt gefördert und von Helmholtz-Zentrum für Umweltforschung GmbH - UFZ, Department Bodenphysik durchgeführt. In this project we experimentally explore the transport of engineered inorganic nanoparticles (EINP) through soils. This is done for original EINPs and some pre-aged form. Transport of NPs in soil is expected to be different from that of reactive solutes, in that hydrodynamic drag, inertial and shear forces as well as the affinity to water-gas interfaces are expected to be more relevant. Hence, the mobility of EINPs in soil is highly sensitive to the morphology of the porous structure and the dynamics of water saturation.This project provides the pore network structure for natural soils using X-ray micro-tomography to allow for an up-scaling of pore-scale interactions explored by project partners to the scale of soil horizons. The pore structure is represented by a network model suitable for pore scale simulations including the dynamics of water-gas interfaces.Pore network simulations will be compared to column experiments for conservative tracers as well as for unaltered and pre-aged EINPs (obtained from INTERFACE). This includes steady state flow scenarios for saturated (ponding) and unsaturated conditions as well as for transient flow to explore the impact of moving water-gas interfaces. The final goal is to arrive at a consistent interpretation of experimental findings and numerical simulations to develop a module for modelling EINP transfer through soil as a function of particle properties, soil structural characteristics and external forcing in terms of flux boundary conditions.

From subsurface structures to functions and texture - linking virtual realities and experiments at the plot and hillslope scales

Das Projekt "From subsurface structures to functions and texture - linking virtual realities and experiments at the plot and hillslope scales" wird vom Umweltbundesamt gefördert und von Karlsruher Institut für Technologie (KIT), Institut für Wasser und Gewässerentwicklung, Bereich Hydrologie durchgeführt. This project will explore the interplay between soil water, tracer and soil heat budgets depending on the prevailing context and develop advanced approaches for their coupled treatment within the subsurface domains of an EFU (the least entity of the CAOS model). Based on an improved understanding of the fingerprints of vertical preferential flow in the water, mass and heat transport in the unsaturated zone we will derive suitable closure relations that account for these fingerprints in the unsaturated subsurface domain of an EFU during rainfall driven conditions. We will furthermore derive descriptions for water, mass and heat budgets in the unsaturated subsurface domain during energy driven conditions and derive the necessary constitutive relations that account for the effect of soil heterogeneity on storage of water, mass and energy based on virtual experiments. Next we will explore coupled water and heat transport in the saturated subsurface domain with special emphasis on groundwater surface water exchange and derive process descriptions of minimum adequate complexity. Furthermore we will contribute to an optimal combination of soil physical and geophysical methods for exploring near subsurface lateral structures at the hillslope scale in joined work task with Project F.

Model coupling and complex structures - Evaporation-driven transport and precipitation of salts in porous media

Das Projekt "Model coupling and complex structures - Evaporation-driven transport and precipitation of salts in porous media" wird vom Umweltbundesamt gefördert und von Universität Stuttgart, Institut für Wasser- und Umweltsystemmodellierung durchgeführt. Degradation of the soil productivity due to salt accumulation (salinization) is a major concern in arid, semi-arid and coastal regions. Soil salinization is an old issue but encouraged irrigation practices have been rapidly increasing its intensity and magnitude in the past few decades. Studies have shown that excess of the irrigated water contributes significantly to evaporation from the bare soil surface and therefore to the salinization. In some parts of the world soil salinity has grown so acute that the agricultural lands have been abandoned. Evaporation salinization is mainly influenced by interaction between the flow and transport processes in the atmosphere and the porous-medium. On the atmosphere side, wind velocity, air temperature and radiation have a strong impact on evaporation. Furthermore, turbulence causes air mixing, influences the vapor transport and creates a boundary layer at the soil-atmosphere interface which indeed influences evaporation. On the porous-medium side, dissolved salt is transported under the influence of viscous forces, capillary forces, gravitational forces and advective and diffusive fluxes. The water either directly evaporates from the water-filled pores or it is transported to air due to diffusive processes. Continuous evaporation promotes salt accumulation and precipitation resulting in soil salinization. In the scope of this work we attempt to develop a model concept capable of handling flow, transport and precipitation processes related to evaporative salinization of an unsaturated porous-medium.

Identification of effective process formulations for evaporation of water from bare soil

Das Projekt "Identification of effective process formulations for evaporation of water from bare soil" wird vom Umweltbundesamt gefördert und von Technische Universität Braunschweig, Institut für Geoökologie, Abteilung Bodenkunde und Bodenphysik durchgeführt. Describing the evaporative movement of soil water towards the soil-atmosphere interface with one-dimensional effective continuum-scale process models can be a valid approach under some conditions, but may lead to erroneous flow predictions under certain circumstances. The aim of this subproject is to explore validity limits of the Richards equation for describing bare soil evaporation in particular during stage-two evaporation, where the soil's unsaturated hydraulic conductivity and vapor diffusion in soil dominate the evaporation process. To analyze limitations arising from neglect of coupled heat and water vapor flow processes and to assess the importance of using a correct hydraulic conductivity function for liquid phase flow, we will evaluate data from a variety of evaporation scenarios by inverse modeling with effective process models. Scenarios cover experiments under transient conditions and include flow interruptions to study dynamic effects. Data will be provided by virtual realities obtained by comprehensive forward modeling by SP2, small lysimeter experiments under laboratory and field conditions, and a joint lysimeter experiment (SP3). In the inverse evaluations, we will start with the full Philip-de Vries model and extensions for non-equilibrium water flow and simplify it stepwise towards the Richards equation in order to assess which model complexity is necessary to adequately describe the measurement data. Our particular interest lies in (i) identifying the relative contributions of liquid and vapor water flow to the total water flow near the surface, (ii) determining the time at which evaporation shifts from stage-one to stage-two, (iii) determining the position of the vaporization plane during stage-two evaporation, and (iv) quantifying the range of conditions where effective process descriptions can be used in practical situations to correctly predict the water fluxes to the atmosphere.

Quantification of active interfaces with respect to dissolved chemicals in unsaturated structured soil

Das Projekt "Quantification of active interfaces with respect to dissolved chemicals in unsaturated structured soil" wird vom Umweltbundesamt gefördert und von Helmholtz-Zentrum für Umweltforschung GmbH - UFZ, Department Bodenphysik durchgeführt. During the first project period we developed a general approach to quantify soil pore structure based on X-ray micro-tomography Vogel et al. (2010) which is applicable at various scales to cover soil pores larger that 0.05 mm in a representative way. Based on this method we generated equivalent network models to numerically simulate flow and transport of dissolved chemicals. The existing network model was extended to handle reactive transport and infiltration processes which are especially critical for matter flux in soil. The results were compared to experimental findings. The original research question 'what does a particle see on its way through soil' could be answered quantitatively for various boundary conditions including steady state flux and infiltration. However, we identified various critical aspects of the proposed modeling concept which will be in the focus of the second period. This includes 1) the spatial arrangement of interfaces having different quality which is crucial for chemical interactions and pore scale water dynamics, 2) the realistic multiphase dynamics at the pore scale which need to reflect the dynamic pressure and movement of trapped non-wetting phase and 3) the parametrization of structural complexity which need to be developed beyond the measurement of continuous Minkowski functions to allow the development of quantitative relations between structure and function. These aspects will be explored in a joint experiments in cooperation with partners within the SPP.

Groundwater Artificial recharge Based on Alternative sources of wateR: aDvanced INtegrated technologies and managEment 8GABARDINE)

Das Projekt "Groundwater Artificial recharge Based on Alternative sources of wateR: aDvanced INtegrated technologies and managEment 8GABARDINE)" wird vom Umweltbundesamt gefördert und von Georg-August-Universität Göttingen, Geowissenschaftliches Zentrum, Abteilung Angewandte Geologie durchgeführt. Aquifers are the main source of water in most semi-arid areas of the Mediterranean basin. As a result of over-exploitation hydrologic deficits of varying acuity prevail in these areas. Seawater intrusion and pollution have been identified as the primary factors for quality degradation. Further deterioration can be expected based on trends in the precipitation regime attributed to climate change. The objective of this project is to identify alternative sources of water and to investigate the feasibility, both environmental and economic of their utilization. Alternative water sources to be artificially recharged comprise: surface water runoff, treated effluent, and imported water. Furthermore, brackish water bodies, present in many aquifers could be utilised after desalination. The project structured into eight work-packages comprehensively addresses all issues related to the problem: expected precipitation rates, recharge and water budgets, identification of potential alternative water sources and technologies for their utilization, development of tools for the management of groundwater resources under artificial recharge conditions, aquifer vulnerability assessment, characterization of the unsaturated zone, and mixing effects. Four test sites have been selected for practical application of the approach. Substantial field testing, integration of technologies and findings to ensure optimal implementations of aquifer recharge alternatives, quantification of socio-economic impacts and development of dissemination platform are planned. Finally a carefully designed project management shall drive and accompany the project execution in order to ascertain consistency and efficiency.

Farm-scale Methane Fluxes (FasMeF)

Das Projekt "Farm-scale Methane Fluxes (FasMeF)" wird vom Umweltbundesamt gefördert und von Eidgenössische Technische Hochschule Zürich, Institut für Agrarwissenschaften, Departement Biologie durchgeführt. The release of the IPCC's Fourth Climate Assessment Report has once more drawn the public attention to the important role that agriculture plays in the global greenhouse gas budgets, namely in the case of CH4 and N2O. In Switzerland, 80.5Prozent of all national CH4 emissions stem from the agricultural sector (year 2007 values). However, these numbers so far lack direct experimental validation in the field and are based on expert knowledge. We thus propose to investigate the CH4 emission processes leading to a clear increase in CH4 concentrations within the nocturnal atmospheric boundary layer. This project will thus aim at validating CH4 emissions at the farm scale as a first step towards a validation at the national scale. We hypothesize that the diurnal cycle in CH4 concentration is the combination of the local surface exchange of CH4 with oxidation by the soil if it is unsaturated or emissions from the soil if saturated, plus a much larger component attributable to emissions from cattle (ruminants). Our specific aim is to quantify CH4 emissions at the farm scale (0.5-5km2) of the ETH Research Station Chamau and relate this to estimates reported in the Swiss National Inventory Report under the Kyoto Protocol. We plan to employ a boundary-layer budgeting method (BLBM) by focusing on the nocturnal boundary layer conditions where steadily increasing CH4 concentrations can be observed during most of the nights. To achieve this, we need the following four components of our experiment: - Eddy covariance flux and concentration measurements to quantify the surface exchange of CH4 (soil production or consumption); - Vertical CH4 concentration profiles to know the vertical distribution of CH4 in the incompletely mixed stable nocturnal boundary layer (NBL), to determine the NBL height and its temporal evolution which are essential information required by the BLBM; - Spatial variation of near-surface CH4 concentrations to address the question how spatially representative our near-surface CH4 concentration measurements actually are. Measurements of stable isotopes, in particular d13C ratios in CH4 will provide additional information about the processes responsible for the CH4 fluxes obtained via the BLBM aproach. Our project will contribute to develop and test a potentially useful method for validating CH4 emissions at the farm scale and larger scales. This project will contribute to our scientific understanding by bridging the spatial and temporal gap in our efforts to quantify and validate CH4 emission estimates at the farm scale to regional scale.

Experimental investigations of soils in the context of underground nuclear waste disposal

Das Projekt "Experimental investigations of soils in the context of underground nuclear waste disposal" wird vom Umweltbundesamt gefördert und von Ecole Polytechnique Federale de Lausanne, Institut des sols, roches et fondations, Laboratoire de mecanique des sols durchgeführt. This request R'Equip is within the context of a research project dealing with an experimental investigation of unsaturated soils behavior under very high temperature, suction, and pressure loadings. The aims of this research program require the development of a new specific apparatus adapted to these extreme testing conditions for LMS-EPFL. Defining the thermo-hydro-mechanical behavior of materials is one of the main modern issues in soil mechanics. In recent years, thermal-geomechanical problems have strongly increased as a result of the demand for new and enlarged types of applications such as high-level nuclear waste disposal, energy extraction from pressurized geothermal reservoirs, heat storage, zones around buried high-voltage cables, geothermal structures, and so on. For sure, one of the fundamental challenges in this field is an insight in the understanding of unsaturated soil behavior at high pressures and temperatures for host rocks and buffer materials for radioactive waste. Several of the leading research teams around the world have now implemented research programs in this area. The aim of the proposed research is therefore the development of a new multi-purpose triaxial cell able to perform tests on unsaturated materials for wide ranges of temperature (20-150 C) and cell pressure (up to 30 MPa) along with suction control. The LMS-EPFL is already involved in two important research projects in the field of the safety study of disposal for vitrified High Level Wastes. The TIMODAZ (Thermal Impact on the Damaged Zone around a Radioactive Waste Disposal in Clay Host Rocks) European project investigates the behavior of two host rocks (Boom Clay from Mol (Belgium) and Opalinus Clay from Mont Terri (Switzerland)) for high level waste repository and a collaboration with the NAGRA (National Cooperative for the Disposal of Radioactive Waste - Switzerland) characterizes the thermo-hydro-mechanical behavior of granular bentonite as a buffer material. To conduct these experimental programs in the best way, the laboratories need to acquire such a triaxial cell adapted for very high thermo-hydro-mechanical loadings. The decisiveness of these experimental programs is to use the test results to define for each material the parameters of ACMEG-TS (Advanced Constitutive Model for Environmental Geomechanics) model developed by the LMS, which takes into account at the same time the temperature and the suction effects on soil behavior. This model will permit to predict the evolution of the clay host rocks or the granular bentonite in order to take into account all the thermo-hydro-mechanical processes in the safety study of disposal for vitrified High Level Wastes.

Development and evaluation of micro push-pull tests to investigate rhizosphere processes

Das Projekt "Development and evaluation of micro push-pull tests to investigate rhizosphere processes" wird vom Umweltbundesamt gefördert und von Eidgenössische Technische Hochschule Zürich, Institut für terrestrische Ökosysteme, Ökosystemmanagement durchgeführt. The rhizosphere, the soil under the direct influence of active plant roots, differs in many aspects from the bulk soil due to root, microbial and fungal activities. Most mechanistic rhizosphere research has been undertaken in microcosms, often in the absence of soil. The understanding of mechanistic processes in the rhizosphere soil is therefore highly fragmented. The use of micro-techniques for the collection of soil solution enables non-destructive in situ observation of soil solution chemistry at high spatial and temporal resolution. Micro suction cups were used successfully in conjunction with rhizoboxes that allow observing the development of root systems through a transparent front plate and allow a localized sampling of soil solution. Suction cups cannot only be used to extract solution from soils but also to inject small amounts of solution. Single-well injection-withdrawal tests, called 'push-pull' tests, have been used since many years for the quantitative determination of a wide rang of aquifer physical, biological and chemical characteristics. In a push-pull test a prepared solution containing one or more solutes and a non-reactive tracer is injected into the aquifer using an existing well; the test solution/ groundwater mixture is then extracted from the same location. Similar to investigations of subsurface microbial activity in aquifers, the scientific community agrees that in situ techniques are needed for rhizosphere research. This project aims to combine micro-suction cups with the push-pull test to create a miniaturized system that will be applicable to study reactions in the rhizosphere. It also aims for the first time to apply a push-pull test to investigate soil solution under unsaturated conditions. These micro-push-pull tests will allow us to get not only concentrations of solutes in the rhizosphere but to study in situ reactions in the rhizosphere at defined distances from the root. This project is based on the combined expertise on rhizosphere sampling and reactions in the Soil Protection Group and the expertise of the Soil Biology group on aquifer push-pull tests and the in situ investigation of microbial activity. The new micro push-pull test is expected to yield new in situ information not only of concentrations in solution but especially of reaction and exudation rates under conditions as undisturbed as possible.

BIOVENTING zur in-situ Sanierung von Mineralöl-kontaminierten Standorten

Das Projekt "BIOVENTING zur in-situ Sanierung von Mineralöl-kontaminierten Standorten" wird vom Umweltbundesamt gefördert und von Universität für Bodenkultur Wien, Department für Agrarbiotechnologie, IFA-Tulln, Institut für Umweltbiotechnologie durchgeführt. BIOVENTING ist ein sehr kosteneffizientes Verfahren zur Entfernung von schwerflüchtigen organischen Schadstoffen (Diesel, Heizöle, Schmieröle, etc.) aus der ungesättigten Bodenzone. Durch Sauerstoffanreicherung im Untergrund (Absaugung der Bodenluft, Eintrag von Umgebungsluft) wird der mikrobielle Schadstoffabbau angeregt. Durch Mineralisation werden die abbau- und verfügbaren Kontaminanten (Kohlenwasserstoffe) aus dem Boden entfernt. Im Rahmen dieses Projektes wurden Methoden zur Ermittlung der Einsatzgrenzen dieses in-situ Verfahrens entwickelt. Neben einer Überprüfung der physikalisch-chemischen Voraussetzungen (Durchlässigkeit, Wassersättigung, Alkalinität, Nährstoffgehalt) werden am Standort Untersuchungen (Bodengasanalysen, in-situ Repirationstests) zur Bestimmung der biologischen Abbaubarkeit der Kontaminanten durchgeführt. Anhand dieser Methoden kann überprüft werden, ob ein kontaminierter Standort durch Einsatz des BIOVENTING-Verfahrens sanieren werden kann.

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