NANOREM · A novel isotope tool to assess nanoparticle toxicity in wetland plants

A novel isotope tool to assess nanoparticle toxicity in wetland plants

NANOREM is a research project aiming to provide the first comprehensive insight into the toxicity of zinc oxide nanoparticles (ZnO-NPs) in wetland plants. This information is essential to evaluate correctly the risk of releasing large quantities of NPs to the environment. In this project we made use of cutting edge isotope techniques to trace the sources of NP pollution, and to understand how NPs might change the current paradigm of metal cycling and assimilation by plants. Furthermore, NPs were synthesized from plants and plant extracts using novel methods and characterized. The four research objectives designed were the following: i) To evaluate the uptake, accumulation and toxicity of ZnO-NPs in Phragmites australis and Iris pseudacorus as compared with bulk ZnO and free Zn2+. ii) To purify ZnO-NPs from Iris pseudacorus extracts and characterize them iii) To determine the effect of urban run-off water on the solubility, stability, aggregation, assimilation and phytotoxicity of ZnO-NPs iv) To measure the Zn isotopic effects associated with the response of macrophytes to ZnO NPs, bulk ZnO and free Zn2+. The conclusions of this action were the following. Zinc oxide is toxic to wetland plants, and the smallest NPs pose a greater environmental risk. NPs smaller than 50 nm released more Zn in solution, and this was taken up by plant roots. Plants treated with NPs<50 nm showed higher Zn concentration in their tissues and more toxic effects than in response to other ZnO materials. Isotope data indicated that a significant portion of NPs < 50 nm reaches the aerial parts of the plant undissolved and could potentially be transmitted through the food chain. Zinc stable isotope analysis was established as a useful technique for the study of NP metabolization by plants. In addition, this action demonstrated that ZnO-NP can be obtained from plant extracts of I. pseudacorus. This development opens the possibility of recovering metals from polluted plant biomass. Finally, a green system for the remediation of run-off water was developed, which effectively removed Zn and Cu. Carex vulpina was the best species in this system, showing the highest biomass production and Zn concentration.

Data: CORDIS, © European Union