Impact Of Copper Oxide Engineered Nanoparticles On Eichhornia Crassipes: Toxicity, Uptake And Distribution, Existing Speciation

With the rapid development of nanotechnology, engineered nanoparticles(ENPs)are widely used in verious aspect of our life because of their unique properties.ENPs will enter into the aquatic system through atmospheric deposition, surfacerunoff and sewage disposal, thus causing potential damage to aquatic environmentand aquatic organism especially aquatic plant-the primary producer. CuO ENPs havebeen widely applied to gas sensor, photovoltaic cell, heat transfer nanofluids, catalystand semiconductorv, the ecotoxic effects of which can not be ignored. This studyinvestigated the phytotoxic effects, uptake, distribution and existing speciation ofCuO ENPsto Eichhornia crassipesvia TEM, EDS and synchrotron radiation. Themain results as follows:(1) Toxicity of CuO ENPs to Eichhornia Crassipes is significantly greater thanthat of BPs, and the released ion fromENPs also shows certain inhibitory to plantgrowth, but not as obvious as ENPs, which means that the biotoxicity effect of CuOENPs is mainly caused by the particle itself.(2) Toxicity of CuO ENPs to Eichhornia Crassipesis concentration-dependant,the higher concentration, the more obvious toxic effect, and with the concentration of50mg/L, the ENPs can significantly inhibit the roots elongation and the emergence ofnew roots, which leads to the decrease of the roots biomass, and the inhibition effectis more significant over time.(3) After CuO NPexposure, the root cap and meristematic zone of EichhorniaCrassipes are serious damaged, with the cell loosely arranges disorderly, root captends to spin off root, and the protection function serious damaged. Root-cuttingappears in root tip elongation zone, but there is no significant effect to the maturationzone.(4) CuO ENPs induced stomatal closure is related to the production of H2O2andthe resulting [Ca2]Iincreases which is an signal transduction material and necessaryfor stomatal closure. As a result, photosynthesis and respiration are inhibited. Leavesof Eichhornia crassipes turn yellow, even rot.(5) CuO ENPs can be absorbed by both roots and the submerged leaves and existin cell wall, cytoplasm, central vacuole. CuO ENPs that uptaken in cells partiallychange into CuS and Cu3(PO4)2. The absorptivity of submerged leaves is about3times higher than that of roots. Thus the submerged leaves are the main way thatENPs enter into Eichhornia crassipes.This research suggests that the submerged leaves are the main pathway thatENPs enter Eichhornia crassipes. Also, it is clear that the phytotoxicity, uptake anddistribution, exsiting speciation of CuO ENPs to large floating aquatic plants. Those results areof importance to analyze the risk of ENPs to water environment.