Das Projekt "Impact of colloidal organic matter on toxic metal bioavailability in urban water cycle" wird vom Umweltbundesamt gefördert und von Ecole Polytechnique Federale de Lausanne (EPF), Environmental Biophysical Chemistry Group durchgeführt. Urban waters are important vectors of xenobiotics (e.g. heavy metals and organic pollutants) towards aquatic environments and their potential toxicity to the receiving waters is of concern. Although it is accepted that pollutant chemical forms have different fate and environmental impact, there are paucity of data concerning the chemical speciation and biouptake of toxic metals in the urban waters. The present project therefore addresses the key issue of linking the speciation and biouptake of priority metal pollutants in urban waters, and in particular the role of the colloidal orga-nic matter (COM). Binding of metals by COM was examined by ion exchange speciation technique in parallel to bioassays with green microalga Chlorella kesslerii. To explore how the size and molar mass distribitions of COM affect their behaviour and metal binding properties, COM and associated toxic metals were also fractionated and characterized by Flow field flow fractionation - multidetection platform, including on-line detection with multiangle laser light scattering, UV, RI and ICP-MS. Final effluents of the waste water treatment plants (WWTP) of Duebendorf, Hinwill and Zurich were sampled in two field trips organized in January 2007 and in February 2008. In both campaigns, determined total and dissolved metal concentrations were below the limits fixed by the water quality directives for surface waters in Switzerland (Oeaux). Humic - like substances of low specific ab-sorption properties and average molar masses between ca. 1000 and 3600 Da were identified as the major colloidal fraction components of the WWTP COM. Significant proportions of metals such Cu, Ni, Zn and Cr were associated to the low molar mass colloidal fractions, and are thus expected to have longer residence time in water than particulate fraction. Interestingly Pb binds preferentially to high molar mass COM, also containing Fe and Al. Furthermore, the uptake of Cd and Cu by alga Chlorella kesslerii was consistent to the speciation analysis and measured free metal ion concentrations, while Pb uptake was larger than that expected from the speciation measurement. These results suggest that the uptake (and potential toxic effect) of Cd and Cu in urban waters can be predicted by the speciation measurements and modelling (e.g. by the biotic ligand model that is currently been used by EPA in USA). In the case of Pb, the interactions of the colloidal organic matter with algae should be taken into account in addition to the chemical speciation.
Das Projekt "Nutzung und Schutz der Wasservorraete im Victoria-See durch nachhaltige Bewirtschaftung der Feuchtgebiets-Uebergangszonen" wird vom Umweltbundesamt gefördert und von Universität Zürich, Institut für Pflanzenbiologie durchgeführt. The project investigates the filtering capacity of wetland-ecotones and the resource use practices and management arrangements of wetland users with regard to different stages of urbanization. The aim of the study is to define options wich will allow to integrate sustainably managed wetlands into urban and rural water and sanitation planning. This will protect wetlands and contribute to the improvement of the inshore water quality. Significance for the partner country: The project contributes to protect wetlands as habitants rich in biodiversity and as resource base mainly for poor people and it contributes to an adequate use of natural wetland-ecotones in wastemaster treatment schemes and thus helps to improve the inshore water quality. The project improves the capacity of the Fisheries Research Institute in its task to monitor the national water resources through improvement of its infrastructure and through training of its staff (short term training of laboratory technicians, M.A., M.Sc. and Ph.D. degrees of research personel). The project helps to enforce the environmental policies of Jinja town through the collaboration of the Environmental Department of the Jinja Municipal Council with the water quality laboratory set up at the Fisheries Research Institute. Accomodation of the project to the research policies of the Partner country: The project is part of the National Wetlands Management Programme which itself follows the guidelines of the National Environmental Action Plan (NEAP). The research project focuses on the sustainable use of surface water, a steadily increasing problem in the densely populated areas around lake Victoria. The Ugandan Freshwater Fisheries Research Organisation (FIRI) and the Institutes of Plant Biology and Ethnology of the University of Zurich will collaborate in an interdisciplinary approach to investigate lake shore ecotones, the potential waste water treatment plant barriers along the lake shore. It is our aim to study the efficiency and the regeneration capacity of ecotones and to find options for sustainable management of wetlands as an integral part of water supply schemes through peoples participation.