C60 Fullerene Soil Sorption, Biodegradation, and Plant Uptake

Assessments of potential exposure to fullerenes and their derivatives in the environment are important, given their increasing production and use. Our study focused on fate processes that determine the movement and bioavailability of fullerenes in soil. We evaluated the sorption, biodegradation, and plant uptake of C-60 fullerene using RC-labeled C-60 solutions in water produced by either solvent exchange with tetrahydrofuran or sonication/extended mixing in water. Organic carbon appeared to have an important influence on C-60 soil sorption. The log K-oc values for C-14(60) were equivalent for sandy loam and silt loam (3.55 log[mL/g]) but higher for loam (4.00 log[mL/g]), suggesting that other factors, such as pH, clay content and mineralogy, and cation exchange capacity, also influence C-60 soil sorption. There was little (CO2)-C-14 production in the silt loam or the sandy loam soil after 754 and 328 days, respectively, suggesting high resistance of C-60 to mineralization in soil. Plant uptake was generally low (similar to 7%), with most of the uptaken C-14 accumulating in the roots (40-47%) and smaller amounts of accumulation in the tuber (22-23%), stem (12-16%), and leaves (18-22%). Our results indicate that C-60 released to the environment will not be highly bioavailable but will likely persist in soil for extended periods.