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Long term behaviour and seasonal cycling of Cs-137 in a eutrophic lake in southern Germany (Kongressschrift / Tagungsband) - Detailansicht

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Grunddaten

Titel der Arbeit (title) Long term behaviour and seasonal cycling of Cs-137 in a eutrophic lake in southern Germany
Erscheinungsjahr 2014
Publikationsart Kongressschrift / Tagungsband
Inhalt
Abstract Lake Vorsee is a small and shallow eutrophic lake with a swampy watershed about 25 km north of Lake Constance in southern Germany which is intensely used for fishing by local fishermen. It is completely overgrown by watermilfoil (Myriophyllum spicatum) which produces thick watery organic sediment layers when it decomposes in late autumn and winter. In 1986 the watershed of Lake Vorsee had a Cs-137 Chernobyl inventory of about 30 kBq/m2. The Cs-137 activity concentration in the water was monitored for more than 25 years and it can be well described by a sum of two exponential functions superimposed by some seasonal cycling.

To analyze the seasonal cycling of the Cs-137 activity concentration in water and in suspended matter, samples were collected with a Large Volume Water Sampler (Midiya-System) on a monthly base and measured gamma-spectrometrically by HPGe-detectors. Also the Cs-137 distribution coefficient kD was determined.

Additionally, in the lake water the concentration of the competing ions K+ and NH4+ was determined by ion-chromatography, total organic carbon (TOC) with a combustion catalytic oxidation / NDIR detection method as well as the dissolved O2-concentration and the pH and temperature of the water by handheld probes. Information on the amount of precipitation was taken from nearby weather stations.

In this project the following hypothesis will be checked: In late autumn the decomposing watermilfoil produces NH4+-ions which exchange Cs+-ions from their binding places, thereby increasing the Cs-137 activity concentration in the water. In spring the watermilfoil starts growing which leads to a larger O2-concentration in the water and helps to disintegrate the NH4+-ions in this way decreasing the Cs-137 concentration again. A possible influence of the other measured parameters on the seasonal cycling will also be discussed.

Zugeordnete Projekte

Wissenschaftliche Veröffentlichungen

Beteiligte Personen (intern)

Klemt, Eckehard, Professor Dr. rer. nat.  
 
 
 

Einrichtungen

Bachelorstudiengang Energie- und Umwelttechnik
Fakultät Technologie und Management
Hochschule Ravensburg-Weingarten
Institut für Angewandte Forschung (IAF)
Masterstudiengang Umwelt- und Verfahrenstechnik
Schwerpunkt Energie und Umwelt (IAF)
Impressum      Erklärung zur Barrierefreiheit