Separation and characterization of high molecular weight organic matter dissolved in freshwaters by TFF ultrafiltration.

Abstract

Tangential flow ultrafiltration (TFF) was applied to separation of high molecular weight organic matter (HMW-DOM, MW>1kD) dissolved in freshwaters. Tens to hundreds mg of HMW-DOM were separated from 80-100 l of waters in yields of 30-70% of total DOC. In a eutrophic lake, stable isotope ratios of C and N tend to be heavier than those in meso to dystrophic lake waters. The C/N atomic ratio is low in the eutrophic lake. Both parameters appear to indicate that thte productivity within the lake should reflect also on tne nature of HMW-DOM. On the contrary, lipid analyses showed that C29 stigmasterol is the major sterol associated with this size of DOM.