CHEMICAL AND MICROBIAL BINDING FORMS OF PHOSPHORUS CONSIDERING THE AVAILABILITY OF NITRATE IN SEDIMENT-WATER SYSTEMS

An analytical registration of P-transport processes in intact sediment cores from the shallow reservoir Radeburg II (near Dresden, Saxonia, Germany) was possible by application of (KH2PO4)-P-32 and followed by sequential P-fractionation (PSENNER et al. 1984). Under oxygen free conditions and sufficient nitrate supply an activity accumulation was found in the uppermost sediment horizon. Nitrate influences above all the BD-fraction (reductant soluble P), so that an interaction between nitrate and the iron binding system could be proved. It could be shown by means of activated sludge (a model object for microbial polyphosphate accumulation from a lab plant qualified for biological P- and N-elimination) that added (KH2PO4)-P-32 was bound within 5 h to about 75% in the NaOH-fraction. The saturation of iron compounds in the activated sludge took place immediately after (KH2PO4)-P-32 had been added. In the same time the portion of the microbial immobilization of added P-32 amounted to 7% in the high-iron sediment from the Radeburg reservoir, whereas evidently in the heat- and HgCl2-sterilized sediments this portion was additionally ascertained in the BD-fraction, too.