ASSESSMENT OF THE MOLECULAR COMPOSITION OF PARTICULATE ORGANIC-MATTEREXCHANGED BETWEEN THE SAEFTINGHE SALT-MARSH (SOUTHWESTERN NETHERLANDS) AND THE ADJACENT WATER-SYSTEM

In this study the chemical composition of seston, transported by tidal water between an estuarine salt marsh and the adjacent water system, was assessed. The analytical techniques used are Pyrolysis in combinat ion with Gas Chromatography and/or Mass Spectrometry. Interpretation o f the Py-MS data was aided by discriminant analysis. The presented res ults indicate that throughout the year a dominant refractory fraction is present in the seston, but that seasonal additions can be distingui shed, Apart from this seasonal pattern, differences between ebb and fl ood can be visualized by the use of discriminant analysis. During summ ertime, flood seston is enriched with lipids and recently synthesized polysaccharides, while during the rest of the year the flood tide samp les contain more (remains of) lignin and polysaccharides than their eb b tide counterparts, The lignin markers comprise only fragments with e xtremely altered (reduced) character, These results, which highlight t he molecular composition of the exchanged seston but do not offer exac t quantitative budget estimations, provide no evidence for export of l ignin-rich particulate halophytic material from the marsh to the water system. On the contrary, based on seston compositions, the water syst em seems to supply lignin-rich particles to the marsh during a conside rable part of the year.