Das Projekt "Improving the verification of non-CO2 greenhouse gas emissions in Europe by the Rn-222 tracer method" wird vom Umweltbundesamt gefördert und von Universität Basel, Department Umweltwissenschaften, Humangeographie , Stadt- und Regionalforschung durchgeführt. Non-CO2 greenhouse gases (CH4, N2O, SF6, halocarbons) are responsible for 37 Prozent of the anthropogenic contribution to global warming. Some of these gases (N2O, SF6, chlorinated and brominated halocarbons) are in addition destructive to the stratospheric ozone layer. Regional emission estimates of non-CO2 greenhouse gases are currently much more uncertain than for CO2. Mostly, they are based on 'bottom-up' approaches relying on inventories of known sources and expected emission functions. The 222Rn flux map of Europe produced in the preceding project permits today a more reliable real-world assessment by the 222Rn tracer method, a so-called 'top-down' approach. In previous studies, source strength of 222Rn has been a major uncertainty. Substantial reduction of uncertainty has been achieved so far and further improvements are aimed for in the present project. Future improvements include in particular a better temporal resolution of the 222Rn flux map. Current developments within the EU-driven European Radiological Data Exchange Platform (EURDEP) open the possibility for quasi real-time updates of the European 222Rn source term. The source strength of 222Rn is a key parameter for estimating the source strength of any gas of interest, based on concentration differences observed in the atmospheric boundary layer over time in both, the gas of interest and 222Rn. There are two ways to obtain concentration differences over time. One is during pollution events at otherwise remote 'background' stations. This approach is followed in an associated project at Jungfraujoch (main applicant: Stefan Reimann, EMPA), where we will contribute the 222Rn related parameters. The other approach is to obtain concentration differences during changes in mixing layer height as observed during nocturnal inversions. This aproach will be applied to the measurement of non-CO2 greenhouse gases in the central part of Eastern Europe (Hungary). Emissions from this region just east of the Alpine Ridge are highly uncertain and can not be detected at Jungfraujoch using the first approach.
Das Projekt "Mercury fluxes and reductive processes in the Alps" wird vom Umweltbundesamt gefördert und von Universität Basel, Umweltgeowissenschaften durchgeführt. Mercury emitted to the atmosphere is a topical issue as it poses a threat to human health and the environment. Recent studies have demonstrated that elemental mercury (Hg0) can be emit-ted in significant amounts not only from anthropogenic sources but also from vegetated terres-trial ecosystems, suggesting that natural sources of mercury are highly underestimated. Other than that, soils are considered effective sinks for atmospheric mercury mainly due to deposition of oxidised mercury species. Studies with terrestrial soils have indicated that geogenic or depos-ited mercury can be (re-)emitted to the atmosphere mainly in its elemental form. However, due to the lack of direct measurements the importance of mercury emissions from vegetated soil surfaces is still controversial. Our gradient measurements of the last five months at Zugerberg indicate slight nocturnal depo-sition of Hg0. The same was observed during another campaign at the Seebodenalp. However, our incubation studies with bare soil from Zugerberg revealed contrasting results. When amended with glucose or dried and rewetted, the incubated soil samples responded with veri-table Hg0 emission boosts. Although this reaction could be largely ascribed to microbiological activity, the role of plants growing on the soil surface is still unclear. We therefore need to in-vestigate how and to which extent Hg0 exchange between soils and the atmosphere is governed by vegetation. We intend to tackle this question with a combined approach of controlled labora-tory experiments with vegetated soil samples and Hg0 gradient measurements at Zugerberg, Oensingen (SO) and the Stubai Valley in Austria. These studies will enable us to describe and quantify the long-term dynamic of Hg0 exchange in uncontaminated terrestrial ecosystems.
Das Projekt "Improving the verification of non-CO2 greenhouse gases" wird vom Umweltbundesamt gefördert und von Universität Basel, Umweltgeowissenschaften durchgeführt. Non-CO2 greenhouse gases (CH4, N2O, SF6, halocarbons) are responsible for 37 Prozent of the anthropogenic contribution to global warming. Some of these gases (N2O, SF6, chlorinated and brominated halocarbons) are in addition destructive to the stratospheric ozone layer. Regional emission estimates of non-CO2 greenhouse gases are currently much more uncertain than for CO2. Mostly, they are based on 'bottom-up' approaches relying on inventories of known sources and expected emission functions. The 222Rn flux map of Europe produced in the preceding project permits today a more reliable real-world assessment by the 222Rn tracer method, a so-called 'top-down' approach. In previous studies, source strength of 222Rn has been a major uncertainty. Substantial reduction of uncertainty has been achieved so far and further improvements are aimed for in the present project. Future improvements include in particular a better temporal resolution of the 222Rn flux map. Current developments within the EU-driven European Radiological Data Exchange Platform (EURDEP) open the possibility for quasi real-time updates of the European 222Rn source term. The source strength of 222Rn (FRn) is a key parameter for estimating the source strength of any gas of interest (Fx), based on concentration differences observed over time in both, gas X (Dx) and 222Rn (DRn): Fx = FRn Dx DRn-1 There are two approaches to obtain values for Dx and DRn . One is during pollution events at otherwise remote 'background' stations. This approach is followed in an associated project at Jungfraujoch (main applicant: Stefan Reimann, EMPA), where we will contribute the parameters FRn and DRn. The other approach to obtain values for Dx and DRn relies on changes in mixing layer height as observed during nocturnal inversions and will be applied to the measurement of non-CO2 greenhouse gases in the central part of Eastern Europe (Hungary). Emissions from this region just east of the Alpine Ridge are highly uncertain and can not be detected at Jungfraujoch using the first approach.
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.
Das Projekt "Transfer over Ecosystems of Reduced nitrogen by Mass Spectrometry (TERMS)" wird vom Umweltbundesamt gefördert und von Forschungsanstalt Agroscope Reckenholz-Tänikon ART durchgeführt. The project 'Transfer over Ecosystems of Reduced Nitrogen by Mass Spectrometry' (TERMS) proposes to adopt Proton Transfer Reaction Mass Spectrometry (PTR-MS) to measure ambient concentrations of ammonia and selected volatile organic nitrogenous compounds. The project also aims at measuring turbulent ammonia fluxes using eddy covariance approaches by taking advantage of the fast time resolution of PTR-MS. The project consists of the following three parts: a) Instrument development: The PTR-MS instrument will be operated in a new mode, using O2+ as the reagent ion instead of H3O+. Because NH3 is a very sticky molecule, memory effects in the inlet system -- including the sampling line and the transfer into the drift tube of the instrument -- limit the time resolution and present major challenges to the application in an eddy covariance approach. A series of optimizations will be performed to lower memory effects to a degree that the losses can be corrected for. b) Concentration measurements of ammonia and other volatile organic nitrogen species: Measurements will be carried out at the NitroEurope grassland site Oensingen in Switzerland. The focus of the ammonia measurements is the characterization of the temporal dynamics of ambient concentrations at diurnal to seasonal time scales, with a special focus on the morning breakup of the nocturnal boundary layer. In addition the concentrations of selected volatile organic nitrogen compounds will be measured in order to assess their relevance for atmospheric chemistry processes. c) Ammonia exchange flux measurements at NitroEurope sites: The modified and improved PTR-MS system will be applied to measure ammonia exchange fluxes with an eddy covariance approach over several months. We focus on temperate grasslands systems that dominate agricultural production in Switzerland, covering about 69Prozent of the agricultural land. On the European scale this fraction amounts to 49Prozent, representing 30Prozent of the total land area. Grasslands are alternately important sinks and sources for reduced nitrogen, and thus influence the fraction of total emitted reduced nitrogen that is deposited downwind onto semi-natural and natural areas. The quantification of exchange fluxes is crucial for the evaluation of the ecological problems related to the N-cycle. The core of the project is a dissertation focusing on the characterization of the concentrations and fluxes of reduced nitrogen compounds over grassland systems. The PhD candidate can build on the large experience of our group both in field measurements and in the application of eddy covariance techniques for flux measurements of reactive trace gases.