SUBMICRON PARTICLES IN THE RHINE RIVER .1. PHYSICOCHEMICAL CHARACTERIZATION

This paper describes a complete sampling, fractionation and characteri zation scheme for submicrometer particles isolated from the Rhine Rive r. Decreasing particle size fractions were obtained by means of gravit ational sedimentation, cascade centrifugation/ultracentrifugation and cascade filtration. These size fractions were analyzed by photon corre lation spectroscopy (PCS), micro-electrophoresis (ME), transmission el ectron microscopy (TEM), light scattering (LS), inductively coupled pl asma-atomic emission spectrometry (ICP-AES) and total organic carbon ( TOC), which gave complementary results concerning the nature of the pa rticles. The data indicated that submicron particles contribute only a small proportion of the total particle mass and volume, but an import ant proportion of the total particle number. Moreover, their specific surface area may be quite large. Associations of submicrometer particl es with organic macromolecules and fibrils, which may have maintained such particles in suspension, were observed.