Soil microbial response to photo-degraded C60 fullerenes. (April 2016) - Berry, Timothy D.
Abstract: Recent studies indicate that while unfunctionalized carbon nanomaterials (CNMs) exhibit very low decomposition rates in soils, even minor surface functionalization (e.g., as a result of photochemical weathering) may accelerate microbial decay. We present results from a C60 fullerene-soil incubation study designed to investigate the potential links between photochemical and microbial degradation of photo-irradiated C60 . Irradiating aqueous 13 C-labeled C60 with solar-wavelength light resulted in a complex mixture of intermediate products with decreased aromaticity. Although addition of irradiated C60 to soil microcosms had little effect on net soil respiration, excess 13 C in the respired CO2 demonstrates that photo-irradiating C60 enhanced its degradation in soil, with ∼0.78% of 60 day photo-irradiated C60 mineralized. Community analysis by DGGE found that soil microbial community structure was altered and depended on the photo-treatment duration. These findings demonstrate how abiotic and biotic transformation processes can couple to influence degradation of CNMs in the natural environment. Highlights: 13 C enriched C60 fullerene was photo-irradiated for 0, 10, 30, or 60 days before being added to soil microcosms. Approximately 0.78% of the 60 day irradiated C60 was degraded in soils during incubation. C60 altered microbial community differently depending on photo-irradiation duration. Abstract : Prolonged photo-oxidation of 13 C enriched labeled C60 fullerene was found to enhance mineralization of the nanomaterials during a 90 day incubation in soil.