Description: Das Projekt "DYTRAC: Dynamik des Transports und der Transforamtion von Colloiden und Partikeln im Lago Ceresio (Lugano-See)" wird vom Umweltbundesamt gefördert und von Universite de Geneve, Institut F.-A. Forel durchgeführt. Removal rates of many pollutants in lake water are controlled by their partition between dissolved, colloidal and particulate fractions. We are investigating this partition using natural radioactive Be isotopes as surrogates for these pollutants. A new particle separation system for big lake water samples (1000 liters) consisting of a continuous flow centrifuge and an ultra filtration device has been developed. In epilimnion of Lake Lugano we are able to measure Be-7 in all 3 fractions. The largest part is found in the dissolved fraction. This may explain the relatively long residence time of Be in lakes. The work has been accompanied by a series of methods aimed at characterising the physico-chemical conditions in the lake at the time of sampling, the nature of the recovered particles, as well as the performance of the system. Electron microscope observations show decreasing number of particles and their sizes from raw to centrifuged and to ultra filtered water. Pilot measurements to study particle dynamics in the deep water have been carried out including tritium-helium water age measurements. Leading Questions: - What is the role of colloids in removal of metals and radionuclides from lake water? - Can Be-7 be used to determine coagulation rate in lakes? - What is the importance of Fe and Mn cycling at redox interface in permanently stratified lake for phosphorous transport? Other objectives of this project are the following: - Determine the role and importance of Fe and Mn cycling at the oxic-anoxic interface for phosphorous fluxes, - assess the nature of fine particles in lower hypolimnion and their transport mechanism (coagulation, settling, resuspension, focusing)?
Types:
SupportProgram
Origin: /Bund/UBA/UFORDAT
Tags: Lugano ? Beryllium ? Mangan ? Seen ? Eisen ? Phosphor ? Rohwasser ? Tracer ? Kolloid ? Gewässerverunreinigung ? Hypolimnion ? Radionuklid ? Radiotracer ? Metall ? Epilimnion ? Gelöste Stoffe ? Flockung ? Wasserströmung ? Hydrochemie ? Isotop ? Koagulation ? Limnologie ? Messverfahren ? Studie ? Wasserprobe ? Filtration ? Partikel ? Schadstoffbeseitigung ? Stofftransport ? Entwässerung ? Lugano-See ? Be-7 ? redox ? scavenging ? See [Binnengewässer] ?
License: cc-by-nc-nd/4.0
Language: Deutsch
Time ranges: 1994-04-01 - 1998-03-31
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