Some Studies on the Problem of “Treibmudde” in Steinhuder Meer

Abstract

Steinhuder Meer is an extremely shallow lake (mean depth 1.35m). The autochthonous sediments are frequently suspended by waves and then drifted by currents (“Treibmudde”). It is usually only the upper few millimetres of the mud which are disturbed. The transportation of suspended matter by the outflow is calculated to be about 500 t dry wt. per year. Due to the phenomenon of “Treibmudde” there may be a heavy silting in the wind-sheltered parts of the lake, with up to 25 cm per year being recorded in seston samplers.

There is a rapid decomposition of nitrogen containing compounds in the “Treibmudde” being even detectable in the seston samplers. In contrast the mineralisation of phosphorus compounds is slower. Indirect evidence is presented for a vertical distribution of phosphorus and iron within the sediments with maxima of concentrations at the surface. The calcium contents of the “Treibmudde” and of the sediments are very low, although probably a biogenic precipitation of lime occurs during summer time.