Importance of colloids in the transport within the dissolved phase (<450 nm) of artificial radionuclides from the Rhône river towards the Gulf of Lions (Mediterranean Sea)
Résumé
The significance of colloidal fractions regarding the transport of artificial radionuclides in
natural water systems is underlined by using sequential ultrafiltration both in the Rhoˆne
freshwater and the marine area under and outside the influence of the river outflow. Indeed,
the Rhodanian aquatic system represents an interesting test site as various artificial radionuclides are released into the Rhoˆne river by several nuclear installations. We focused our
study on 137Cs, 106Ru, 60Co, 238Pu and 239+240Pu. Our results show that Fe, Al and Organic
carbon (OC) are the main components of colloidal matter. Colloids represent about 15% of
dissolved (<450 nm) OC and 25% of dissolved Fe and Al exported towards the sea. Within
the dissolved (< 450 nm) phase, these colloidal compounds are shown to account for the
transport of 40% for both Co and Ru, 60% for 238Pu and 239+240Pu and have no significance
on 137Cs flux