Phytotoxicity and accumulation of copper oxide nanoparticles to the Cu-tolerant plant Elsholtzia splendens

Abstract

The release of nanoparticles (NPs) to the environment poses an increasing potential threat to biological systems. This study investigated the phytotoxicity and accumulation of copper oxide (CuO) NPs to Elsholtzia splendens (a Cu-tolerant plant) under hydroponic conditions. The 50% effective concentration (EC₅₀) of CuO NPs to E. splendens was about 480 mg/L, implying the tolerance of E. splendens to CuO NPs. The Cu content in the shoots treated with 1000 mg/L CuO NPs was much higher than those exposed to the comparable 0.5 mg/L soluble Cu and CuO bulk particles. CuO NPs-like deposits were found in the root cells and leaf cells. Cu K-edge X-ray absorption near-edge structure analysis further revealed that the accumulated Cu species existed predominantly as CuO NPs in the plant tissues. All these results suggested that CuO NPs can be absorbed by the roots and translocated to the shoots in E. splendens.

Keywords::

• CuO NPs
• toxicity
• dissolution
• tolerant
• translocation

Acknowledgments

The work was supported by the National Natural Science Foundation of China (21177109, 11179025) and Program for New Century Excellent Talents in University (NCET-11-0455). We would like to express our gratitude to Lirong Zheng, Jing Zhang at the Beijing Synchrotron Radiation Facility (BSRF) XAFS beamline station for their generous help.