Cerium oxide nanoparticles influence the life cycle of spontaneous plant species

The tumultuous development of nanotechnology, a new emerging field of science, and the consequent increasing use of engineered nanomaterials (ENMs) in different products and applications are considered a potential threat not only for human health but also for the environment. Studies regarding the impacts of such materials on living organisms and biota and their potential transfer through the food web are analyzed in very few studies and are still at an early stage. Released ENMs could accumulate into environmental compartments where they could establish complex interactions with different abiotic and biotic components, especially in terrestrial ecosystems. Different studies, regarding ENMs, focus the attention on crops, but the effects of these new materials on common and spontaneous species are quite completely unknown and poorly investigated. This aspect could be important in view of a future possible Ecological Risk Assessment. Cerium oxide nanoparticles (nCeO2) are one of the most widely utilized ENMs in Europe and have a great potential to accumulate and affect the environment because of their widespread applications in commercial products. The remarkable and rapid increase in the use of CeO2 nanoparticles in many application areas caused the spread of these materials even in the different environmental matrices. For example, when CeO2 reached the soil, it could be absorbed by vegetation, it could go down deeper into the soil layers, contaminating aquatic groundwater, or it could also enter into the food chain. A germination experiment and a pot soil study were carried out in order to observe the response of 3 spontaneous plant species (Holcus lanatus L., Diplotaxis tenuifolia L. DC. and S. flos cuculi L.) and to different concentrations of nCeO2 having different dimensions (25 nm and 50 nm, respectively). Germination and root elongation, plant growth parameters and nCeO2 uptake and bioaccumulation were investigated. In the 3 pecies, nCeO2 treatments increase the percentage of germination and stimulate root elongation in the first stages of plants. Moreover, they increase the development of roots if it is compared with control and the same comparison could be done for leaf area, with higher values in treated plants than in control ones. ICP – MS analysis highlight that, at the same high concentration of nCeO2, plants absorb more 25 nm particles than 50 nm, because nCeO2 50 nm tend to agglomerate and their uptake becomes more difficult.