ENZYMATIC RELEASE OF PHOSPHATE IN SEDIMENTS OF VARIOUS ORIGINS

Enzymatic liberation of molybdate reactive phosphorus (MRP) (equivalent to orthophosphate) from sediment extracts, obtained from sediments sampled from different parts of a subwatershed of Lake Leman, was investigated. Several hydrolytic enzymes; alkaline phosphatase, phosphodiesterase, RNase. DNase and phytase were used alone or in combination. As expected the release of MRP by combination of alkaline phosphatase with the other enzymes was more efficient than by alkaline phosphatase alone. in all cases, MRP enzymatically released accounted for less than 4% of the total phosphorus in the sediment but represented between 5 and 23% of the organic phosphorus. The highest percentage was obtained with the sediments polluted by domestic sewage. Traces of MRP were liberated by phytase only with the sediment of forest and agricultural origin. Phosphomonoesters were detected in each sediment as well as nucleic acids (except in the natural sediment). This study has shown that it seems possible to characterize organic phosphorus of sediments using this procedure.