Distribution of fullerenes (nC60) between sediment and water in freshwaters

Depending on environmental conditions, fullerenes (nC60) have the potential to settle to the bottom sediments. In this study the distribution of nC60 was investigated in the labile zone between sediment and water. Three freshwater-sediment systems representing oligohumic, mesohumic, and polyhumic lakes with varying sediment composition and structure were used to investigate the target of fullerenes. The largest portion of water suspended fullerenes was found in the sediment, but a part re-suspended relatively quickly to water-stabile particles associated with natural particles. Rapid initial re-suspending was followed by a slower one offering a continuous pathway to the water phase. Re-suspending was highest from the sediment with a high amount of amorphous matter, small particles and a highly aliphatic character, amounting to 9±1% of the initial amount of fullerenes, whereas it was 4±1% in aromatic sediments with larger particles and less amorphous matter. These results indicate that bottom sediments can retain fullerenes but a portion may remain mobile depending on sediment character. Re-suspended fullerenes may again be available to aquatic species-this knowledge should thus be taken into account in the environmental risk assessment of fullerenes.