Das Projekt "Critical Limits and Effect Based Approaches for Heavy Metals" wird vom Umweltbundesamt gefördert und von Eidgenössische Forschungsanstalt für Wald, Schnee und Landschaft durchgeführt. Heavy metals are emitted in the atmosphere by industrial activities, transported through long distances, they deposit and accumulate in terrestrial ecosystems. The problem of Long-Range Transboundary Air Pollution of Terrestrial Ecosystems (LRTAP) includes cadmium (Cd), mercury (Hg) and lead (Pb) and are priority metals in the United Nations / Economic Commission for Europe (UN/ECE) Convention from 1998. Increased accumulation of Cd, Hg and Pb from anthropogenic and geogenic sources in soils especially of forest soils has led to exceedances of the current guide values defined by the environmental legislation. Especially, Hg as a global pollutant is of high ecotoxicological concern. However, little information is available on rates of atmospheric deposition, distribution, mobility of Hg compounds (methylmercury) in soils and their transfer functions in the biosphere (bioaccumulation). An impact of current Hg (Cd and Pb) concentrations on the soil ecosystem is possible but still unknown. Aims: This study is part of a comprehensive investigation to determine Hg (Cd and Pb) levels in the soil matrix, soil solution, fungi, earthworms and their food sources (soil, leaf and root litter) and to evaluate the ecotoxicological effects of Hg on the soil microbial communities. What is the current situation of Cd, Hg and Pb in Swiss forest soils? What are the transfer functions of Cd, Hg and Pb from soil to earthworms and mushrooms? Which microbial parameters (microbial activities and/or bacterial community structures) are most suitable to reveal effects of Cd, Hg and Pb on forest soils? Which heavy metal species in soil can be considered as appropriate predictors of Cd, Hg and Pb bioavailability to microbial communities in soils? Which soil bacterial groups are affected by Cd, Hg and Pb? Are the current critical limits for the total dissolved Cd, Hg and Pb, suggested by the UN/ECE, in accordance with the values estimated for Swiss forest soils? Methods: - Determination of reactive heavy metal pool in soil: Water-extractable HM; Heavy metal specific bacterial biosensors (quantification of lux-gene); Modeling of free ions (WHAM 6). - Determination of microbial activity: - Soil respiration; Nitrification; Phosphatase, beta-Glycosidase. - Changes of total bacterial communities: T-RFLP and DGGE fingerprinting of 16S rRNA gene; Cloning and sequencing; Design of specific primers for detecting HM tolerant bacterial groups.
Das Projekt "Ozone Risk Assessment - O3FLUX" wird vom Umweltbundesamt gefördert und von Eidgenössische Forschungsanstalt für Wald, Schnee und Landschaft durchgeführt. Rationale: Within the frame work of the UNECE Convention on Long-Range Transboundary Air Pollution, the WSL investigates the assessment of ozone risk for forest ecoystems on the basis of ozone fluxes on a European-wide level. The scientific community agrees that from a plant physiological point of view a flux-based approach is superior over the currently applied concentration based (AOT) approach. However, for forest trees, the current state of knowledge allows a simplified and so far not-validated flux approach only. In order to improve the accuracy of the flux approach, it was suggested - to establish a European-wide network of sites where dose-response relationships can be studied to validate the suggested EMEP-photooxidant flux model, - to establish experimental free air fumigation systems to allow mechanistic studies excluding influencing factors as they may occur in chamber studies, - to consider further plant physiological plant response parameters - in addition to the so far applied growth parameter - for the investigation of dose-response relationships. Objectives: Based on the current discussions and the identified gaps of knowledge from the most recent workshops on the establishment of critical levels for ozone at Level II and the application and development of a flux-based concept to protect European forest ecosystems from tropospheric ozone, the WSL aims to contribute towards the development of a scientifically robust flux-based model parameterization to quantify the flux-response relationships under real field conditions. In particular, the WSL aims - to increase our understanding of the effective ozone flux, - to quantify the flux-response relationships for physiological response parameters and the development of ozone visible injury to determine the respective critical flux, - to foster the bio-indicator approach on the Swiss Level II plots, - to produce a tree species specific ozone risk map for Switzerland based on determined critical fluxes, - to take advantage of already existing data-bases for validation of the model parameterization for Norway spruce (Picea abies), - to provide new data for validation of the stomatal flux model for seedlings of main tree species, native to the central European regions, - to utilize field data available in the ICP-Forests data-base (assessment of ozone visible injury on the Swiss Level II plots since 1999), - to provide additional data for parameterization of the EMEP stomatal uptake model, with emphasize on the regional variation. Expected results: Our findings and results are expected to be used for the parameterization and validation of the EMEP-photooxidant flux model which is currently being refined within the framework of the UNECE Convention on Long-Range Transboundary Air Pollution, leading to a revised version of the Gothenborg Protocol to abate acidification, eutrophication and ground-level ozone.