Description: Das Projekt "Understanding biomineralization and its implications for the environmental chemistry of selenium" wird vom Umweltbundesamt gefördert und von Fachhochschule beider Basel - Nordwestschweiz durchgeführt. Due to the tendency to bioaccumulate, trace concentrations of selenium in fresh waters have led to disastrous toxicity effects on water birds and fish in the past. Although this adverse impact was first noticed in the early 1980s, to date no sustainable solution has been found for the remediation of selenium contaminated drainage and waste waters. Compared to water soluble forms, elemental selenium is considered less toxic. Therefore, various remediation approaches try to use microorganisms that are highly efficient in reducing selenium oxyanion concentrations by formation of insoluble elemental selenium. Such biogenic elemental selenium, however, does not crystallize to large particles and remains dispersed in solution as a colloidal suspension, thus being subject to re-oxidation, uptake and assimilation by biota. The probable reason for the tendency of biogenic selenium to remain in solution suspended as nanoparticles is an organic polymer layer modifying the surface, preventing crystallization and conferring the selenium core with physico-chemical properties different from particles without such a layer. To date, it is not known, which molecules (proteins, (poly)saccharides, etc.) form this organic polymer layer. Consequently, it is furthermore unknown, if all microbial groups mediating selenium reduction (either via a respiratory or via co-metabolic reduction) produce the same organic polymer layer around the selenium core. The physico-chemical properties of the layer, however, will strongly influence sedimentation and transport processes of selenium in the environment. Due to the complex chemistry and the nanocrystalline character of the selenium particles, uncertainties persist concerning the selenium solid phase, which is formed biogenically. It is not known, if and to which extent selenium that bears such a polymers layer is subject to further biotic and abiotic oxidation and reduction processes, although these processes will largely govern the ecotoxicological effects of selenium. The present project aims at filling the gaps in understanding biogenic selenium formation by systematically investigating the morphology and speciation of the solid phase and the surface modification mechanisms. By direct (spectroscopic) methods we will determine selenium solid phase speciation and its transformations under environmental conditions. We will develop methods allowing the identification of the organic polymer layers modifying selenium nanoparticles by different microbial groups. Thus we will be able to deliver a mechanistic model describing both layer and core of biogenic selenium nanoparticles and the possible impact(s) they have on each other.
Types:
SupportProgram
Origin: /Bund/UBA/UFORDAT
Tags: Bär ? Süßwasserfisch ? Wasservogel ? Basel ? Kohlenhydrat ? Morphologie ? Polymer ? Pflanzensamen ? Schadstoffbelastung ? Selen ? Umweltchemie ? Industrieabwasser ? Kolloid ? Ökotoxikologie ? Ökotoxizität ? Wirkung ? Krankenhaus ? Assimilation ? Bildung ? Abwasser ? Bohrkern ? Dränung ? Kristallisation ? Oxidation ? Redoxreaktion ? Toxizität ? Mikroorganismen ? Reinigung ? Wasser ? Effektkonzentration ? Vermerk ? Nanopartikel ? Wirkungsmodell ? Entwässerung ? Partikel ? Sedimentation ? LOESUNG ? UNGELOEST ? EINSATZ ? VERRINGERUNG ? ZUSCHUETTUNG ? MECHANISMEN ? UNLOESLICH ? METHODE ? NACHHALTIG ? Dispergierung ? NEU ? OBERFLAECHE ? UNTER ? PROJEKT ? SCHICHT ? VERARBEITEN ? SONSTIG ? VERFRACHTUNG ? FORMBLAETTER ? STARK ? GEGENWART ? GEMISCHT ? THEMA ? VERGLEICHEN ? UEBERRESTE ? GRUPPE ? KONTAMINIEREN ?
License: cc-by-nc-nd/4.0
Language: Deutsch
Time ranges: 2009-10-01 - 2011-09-30
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