The Stress On The Wetland Plants Of Zinc Oxide Nano Particles

Zinc Oxide nanoparticles ?ZnO NPs? are being widely applied in catalysis, optoelectronics, paint and other aspects due to their unique nature of the small size effect, large specific surface area effect and quantum effects. Throughout the whole nano materials market, the proportion of ZnO NPs has exceeded 5%. ZnO NPs has become one of the most promising nano materials. However, with the widely application of ZnO NPs, it bound to flow into the body of water and it will directly or indirectly affect the ecosystems. We research the stress effect of ZnO NPs to wetland plants, which will make us know that ZnO NPs have influence on wetland plants and transport and migration in ecosystems explicitly. It will have an important practical significance and provide a theoretical basis and technical support for removing the pollution of ZnO NPs.In the study, we choosed different kinds of wetland plant ?Ryegrass, Schoenoplectus tabernaemontani, Arundo donax var? as our objects and investigated the impact of different concentrations of ZnO NPs on their seeds germination rate. The results indicated that ZnO NPs almost have no impact on the Ryegrass, Schoenoplectus tabernaemontani, and Arundo donax var seeds germination rate at its low concentration ?0.1 mg/L,1 mg/L?; but it caused a downward trend at its high concentration on Ryegrass and Schoenoplectus tabernaemontani ?100mg/L?. The degree of ZnO NPs inhibited wetland plants seeds germination:Schoenoplectus tabernaemontani> Ryegrass> Arundo donax var. The seeds of Arundo donax var germination rate were not obviously different when compared to the control group at different concentrations of ZnO NPs, but the root and steam length of Arundo donax var was significantly shorter comparing with the control group at high ZnO NPs concentration ?100mg/L?.Eichhornia crassipes was selected to explore the absorption and translocation of ZnO NPs ?0.1mg/L?500mg/L? in the hydroponic system According to our research findings, there were different decline of the content of Zn under different intial concentrations of ZnO NPs. Under different concentrations of ZnO NPs, there was a significant positive correlation between the intial concentration of ZnO NPs and the concentration of Zinc accumulation in stems and leaves ?r=0.99, p=0.01<0.05?. The accumulation of zinc was greater in roots than in stems and leaves. Comparing the accumulation of zinc among ZnO NPs, Zn²⁺ and ZnO MPs experiment group, we found that Eichhornia crassipes easily absorbed Zn²⁺, but there is no big difference between the absorption of ZnO NPs and ZnO MPs. Within the range of the experiment, there was a significant difference between the intial concentrations of ZnO NPs and the control group in the moisture content of the roots system ?p<0.05?, but there was no significant different between the moisture content of the stems and leaves system comparing to the control group.Acorus calamus was selected for investigating hydroponic system and soil system under the stress of ZnO NPs to observe the change of antioxidant enzymes ?SOD?POD?CAT? and MDA. It turned out that the change of antioxidant enzymes was small at the low concentrations ?0.01 g/kg? in soil system, but the activity of the antioxidant enzymes was induced with the trend of increasing first and then slowed down at the high concentrations ?0.1g/kg, lg/kg,2g/kg?, the change of antioxidant enzymes in ZnO NPs experiment was smaller than Zn²⁺, but it was bigger than the experiment of ZnO MPs in soil system. The activity of the antioxidant enzymes was induced with the trend of increasing first and then slowed down or just in flat trend at 10mg/L-50mg/L in hydroponie system, it showed that anti-oxidation mechanism was aroused by ZnO NPs. The activity of the antioxidant enzymes was significantly reduced when the concentrations of ZnO NPs was 100Omg/L or Zn²⁺ was 50mg/L. SOD of Acorus calamus was activated at first, POD was active after that and CAT was caused in the end. The MDA of Acorus calamus was accrued in high concentrations in soil system ?lg/kg,2g/kg? and in hydroponic system ?50mg/L-500mg/L?, it indicated that high concentrations of ZnO NPs would have some toxic effect on Acorus calamus.