Fate of radiolabeled C60 fullerenes in aged soils

Fullerenes (e.g. C-60, C-70, etc.) present in soil may undergo changes in its retention with aging. In this study, the partitioning behavior of (C-14)-C-60 aged up to 12 weeks was investigated in biosolids-amended soil. Spiked samples were subjected to sequential partitioning using water, methanol, and toluene followed by total combustion of solids; the distribution of C-14 across solvents and matrices were used to provide insights on C-60 behavior. In most samples, C-14 only partitioned in toluene with the remaining (non-extractable) activity detected in the solid phase. In all biosolids-amended soil samples, an increase in non-extractable C-14 were observed for those exposed to light (vs dark) with the greatest difference observed in biosolids + sand samples. Possible processes that contribute to the observed C-14 distribution, i.e. retention and potential transformation of C-60, were discussed. Over-all, results suggest that environmental exposure to C-60 and potentially transformed C-60 species, as a result of their release from soils, is likely to be low. Crown Copyright (C) 2016 Published by Elsevier Ltd. All rights reserved.