Uptake, transportation, and accumulation of C fullerene and heavy metal ions (Cd, Cu, and Pb) in rice plants grown in an agricultural soil.

The mutual influences of C fullerene (C) and heavy metal ions (Cd, Cu, and Pb) on the uptake, transportation, and accumulation of these coexisting pollutants in four rice cultivars planted in agricultural soil were investigated during the whole life cycle of rice. The biomass of the rice plants was not affected significantly by the presence of C. C exposure exerted different impacts on the bioaccumulation of Cd, Cu, and Pb in various rice tissues. For example, the bioaccumulation of Cd in rice 9311 panicles was significantly decreased (p < .05) when it was exposed to 1000 mg/kg C, whereas the changes of Cu and Pb levels in panicles were not statistically significant. C was absorbed by rice roots and transported to the stems and panicles, and it tended to form aggregates in rice tissues. C concentrations in the roots, stems, and panicles of the four rice cultivars that were harvested after a 130-day exposure to 600 mg/kg C were 40-292, 4.4-24.5 and 0.077-1.2 mg/kg (dry weight), respectively. C and heavy metal ions exhibited different uptake and transportation mechanisms, which depended on the rice cultivar, soil heavy metal ion concentration, and C exposure time and concentration. For example, the average C in the four rice cultivars was increased sharply, from 47.4 to 196.3 mg/kg from the tillering to booting stages, whereas Cd levels increased only slightly, from 23.1 to 25.9 mg/kg. The study demonstrated that the bioaccumulation of C and heavy metal ions under co-contamination scenario differs from under single contaminant. The accumulation of C in rice panicles may increase the concern of food safety.