Roles of multiwall carbon nanotubes in phytoremediation: cadmium uptake and oxidative burst in Boehmeria nivea (L.) Gaudich

Abstract

Multiwall carbon nanotubes (MWCNTs) have been widely used recently and their interaction with heavy metals or plants will influence the phytoremediation of heavy metal contaminated sites. This study aimed to investigate the effects of MWCNTs on cadmium (Cd) accumulation and Cd-induced oxidative damage in plants. Boehmeria nivea (L.) Gaudich (ramie) seedlings were cultivated in Cd-contaminated river sediments with exposure to 100, 500, 1000 and 5000 mg kg⁻¹ MWCNTs. Results showed that MWCNTs at 500 mg kg⁻¹ promoted the accumulation and translocation of Cd in ramie seedlings and alleviated Cd-induced toxicity by stimulating plant growth, reducing oxidative stress, activating antioxidant enzyme activities and increasing specific antioxidant content. In contrast, plant growth inhibition, Cd accumulation reduction and oxidative damage aggravation were observed in ramie seedlings exposed to 5000 mg kg⁻¹ MWCNTs. These findings demonstrated that the application of MWCNTs at suitable levels could improve the phytoremediation efficiency in the restoration of heavy metal contaminated river sediments, and the inevitable release of MWCNTs at high levels would exacerbate metal-induced toxicity to plants. This study provides a novel method to facilitate the phytoremediation of heavy metal contaminated sediments using nanomaterials and explores the potential risks of nanomaterials to the biological system.