Degradation and Microbial Uptake of C₆₀ Fullerols in Contrasting Agricultural Soils

The environmental fate of functionalized carbon nanomaterials (CNM) remains poorly understood. Using ¹³C-labeled nanomaterial we present the results of a study investigating the mineralization and microbial uptake of surface-functionalized C₆₀ (fullerols) in agricultural soils with contrasting properties. Soil microcosms rapidly mineralized fullerol C, as determined by ¹³C-content in the respired CO₂, with higher fullerol mineralization in an organic, clay-rich soil versus a silty, low C soil (∼56.3% vs ∼30.9% fullerol C mineralized over 65 days). By tracking the enriched ¹³C from fullerol into microbial phospholipid fatty acids (PLFA) we also report, for the first time, the incorporation of nanomaterial-derived C into soil microbial biomass, primarily by fungi and Gram-negative bacteria. While more fullerol C was incorporated into PLFA in the organic C-rich soil (0.77% vs 0.19% of PLFA C), this soil incorporated fullerol C into biomass less efficiently than the silty, low C soil (0.13% and 0.84% of assimilated fullerol C, respectively). These results demonstrate that, in contrast to pristine C₆₀, surface functionalized C₆₀ are unlikely to accumulate in surface soils and are readily mineralized by a range of soil microorganisms