Investigations into the manganese release and content of the sediment upper layers in lake constance west germany
Ostendorp, W.; Frevert, T.
Archiv fur Hydrobiologie, Supplementband 55(3-4): 255-277
ISSN/ISBN: 0365-284X Accession: 005748983
An investigation into Mn distribution in Lake Constance, West Germany (Obersee and Untersee-Gnadensee) upper sediment layers was carried out using dry sediment from 112 sediment cores (each 35 mm long). The analysis showed a vertical and lateral differentiation only in Obersee. The mechanisms of Mn increase in the upper sediment layers and the horseshoe-shaped accumulation zone in the middle of the lake are discussed. In a complementary pe(redox)/pH-controlled laboratory experiment with a natural sediment-water-system it is shown that Mn can be mobilized out of the Obersee sediment at an O2 concentration of 4.5-3.5 mg/l and a corresponding pe > 3.9 < 5.0 (pH = 7.1). The pe-value (electron activity) as a Mn mobilization parameter is discussed. The distribution of Mn in the Obersee sediment is a result of interacting hydromechanical and redox-chemical effects.