Characterisation of riverine particulate organic matter by pyrolysis-gas chromatography-mass spectrometry

Particulate matter samples were collected in the mountainous section and river mouth at the Tech River basin, south France, during flood (December 1996) and summer (September 1997) periods. Suspended material was analysed by pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) and 23 identified pyrolysis products were divided into five main fractions: aminosugars, aromatic hydrocarbons, polysaccharides, phenols and nitrogenous compounds. Analysis of relative amounts of these fractions revealed neither significant spatial nor temporal changes in the particulate organic matter composition. Nevertheless, their specific composition showed that during flooding there is a certain homogeneity in the composition of the riverine particulate organic matter, with more degraded material of pedogenic (allochthonous) character, and during the summer the results suggest the presence of two components, allochthonous and autochthonous.