Effects Of Graphene Oxide And/or Cd On Piant Growth

As one of graphene family,graphene oxide(GO)has excellent properties and extensive application prospects.With the increase of GO applications,it is inevitable to enter into environment,and thus it may cause negative impacts on environmental organisms.In addition,because of great adsorption capacity,GO may change environmental behavior and eco-toxicity of existing pollutants in the environment,and thus exhibit indirect impacts.However,it is little known about this subect.In this study,GO and cadmium(Cd)were used as target pollutants and maize was as target organism to investigate effects of GO or/and Cd on maize growth.The aim is to elucidate the direct and indirect effects of GO on environmental organisms,and provide reference for scientific evaluation on GO impact of GO on environment.The main results are as follows:(1)Hydroponics experiments showed that GO and Cd alone treatment reduced the biomass of maize;When two pollutants coexisted,a certain concentration of GO caused the maize to absorb more Cd.For example,the GO 500+Cd 20 coexistence experiment group increased the Cd content of maize root absorption by 66.46%compared to single 20 mg/L Cd treatment.(2)Pot culture experiment shoed that GO and Cd alone inhibited the photosynthesis of maize leaves;however,when GO and Cd coexisted,GO reduced the negative impacts of Cd on biomass and net photosynthetic rate,while GO increased the negative effects of Cd on stomatal conductance,transpiration,and intercellular CO2 concentration in maize leaves.GO and Cd alone caused increase in MDA content and SOD activity in the leaves of maize,and decreased in the chlorophyll content.When GO and Cd coexisted,GO decreased the trend of MDA content and SOD activity caused by Cd,and also reduced the adverse effects of Cd on chlorophyll.The presence of GO in soil culture significantly promoted the uptake of Cd by maize.The Cd content absorbed by corn leaves in the coexistence experiment group of GO 1500+Cd 5 was increased by 54.84%compared with the treatment with 5 mg/kg Cd alone.(3)Pot culture experiment showed that high concentrations of GO((?)500 mg/kg)increased urease activity in rhizosphere,while Cd inhibited urease activity.In the coexistence of GO and Cd,Cd showed greater inhibition on urease activity than its single.GO also increased phosphatase activity in rhizosphere,while Cd decreased phosphatase activity.When two pollutants coexisted,the presence of GO reduced the inhibitory effect of Cd on phosphatase activity.GO or/and Cd caused a significant change in microbial biomass and community structure in rhizosphere,and the presence of GO changed effects of Cd on microbial biomass and community structure in rhizopshere.(4)The main Cd speciation was change from residual speciation to acid-soluble and reducible speciations in rhizosphere soil.The presence of GO changed the distribution of Cd in the rhizosphere soil,for example,in the treatment of 5 mg/kg Cd,the acid-soluble state in the rhizosphere soil was the largest proportion.The addition of high-concentration GO(= 500 mg/kg)increased the proportion of reduced state,which accounted for the largest proportion.