MONOSACCHARIDE COMPOSITION OF SUSPENDED ORGANIC PARTICULATE MATTER INRELATION TO ITS ORIGIN

Samples of phytoplankton cultures and of suspended particulate matter from continental, brackish and marine waters were examined by HPLC for the monosaccharide content of their hydrolysable sugar fraction. Eigh t monosaccharides were currently assayed and their weight compared to HPLC-assayed chlorophyll a concentrations. With the exception of oligo trophic waters, these two variables are well correlated in the various prospected environments. Glucose was always the strongly dominant for m, not only in fresh and brackish waters but also in marine samples wi th high phytoplanktonic biomass. If samples are compared on a salinity basis, only four monosaccharides showed significant differences in th eir relative concentrations, as a consequence of sampling location: ri bose, galactose and mannose contents were higher in marine waters (sal inity > 35) and arabinose in brackish or fresh waters (salinity < 25). On the other hand, no significant difference appears between the two respective average glucose relative concentrations. No direct relation ship could be established between the origin of organic matter (marine or continental) and monosaccharide ratios or an order of monosacchari de predominance in hydrolysable sugar fraction. But the occurrence of phytoplanktonic bloom was frequently associated with an enhancement of glucose relative concentrations as compared to other monosaccharide f orms. Moreover, ribose and galactose relative values can provide valua ble information and appear to be linked to phytoplanktonic biomass in marine waters.