Biosorption Characteristics Of Mercury In Paspalum Distium L. And The Migration Distribution Characteristics

In this study,Paspalum distichum.L was selected as the research object for phytoremediation of Hg contaminated water.A series of indoor hydroponic experiments were carried out to study the influencing factors of adsorption kinetics,the different forms of mercury enrichment and conversion degree,and its mechanism.The purpose is try to find the the mechanism and application value of Paspalum distichum.L for the remediation of Hg contaminated environment.The main results obtained in this paper are as follows:?1?The adsorption process of Paspalum distichum L for Hg²⁺followed Pseudo Second-order Kinetic Model,all the numerical range of linear coefficient R² ranged from 0.996 to 0.999.The linear coefficient R² of Intraparticles Diffusion Model ranged from 0.912 to 0.989 and 0.947-0.988,and the change of rate constant k3 was opposite with the Pseudo Second-order Kinetic rate constant k2.This implies that the intraparticle diffusion also influence the two adsorption processes.?2?After Paspalum distichum L exposed to Hg²⁺contamination,high concentrations of total mercury were detected in the plant tissues.The maximum value is 2129 mg·kg^-1.MeHg were determined in plant samples during the cultivation of Paspalum distichum L in Hg²⁺solution.The higher of initical Hg²⁺concentration,the higher of MeHg contents in plant samples with the maximum value of 230±157 ng·g^-1.Both cultivation time and concentration affect the methylation capacity of Hg in vivo of Paspalum distichum L:higher Hg²⁺concentration and longer cultivation period would promote the methylation ability of Hg²⁺.?3?After Paspalum distichum L exposed to MeHg⁺contamination,THg for Paspalum distichum L were significantly higher than that exposed to MeHg⁺contamination,the highest value was 9.88±14.3.However,the transfer ability was significantly lower than that in Hg²⁺solution,the lowest value was 0.329±0.165.This resulted in a large number of Hg are accumulated in root of Paspalum distichum.L and it is difficult to transfer to shoot.In addition,the initical MeHg concentration in solution could affect Hg concentration in plant samples increased,but not for the enrichment and transformation ratios.?4?Iron plaque in roots was benefit for the accumulation of THg and MeHg in Paspalum distichum.L in Hg²⁺solution,but was against for the transportation of Hg in plant.And iron plaque promoted Hg methylation in Paspalum distichum.L.The incubation time is a major factor for MeHg accumulation in Paspalum distichum.L in MeHg⁺solution.In the short period?<200 hours?,iron plaque inhibited the accumulation of MeHg by Paspalum distichum.L.However,this phnenomenen disapped follow the cultured time,and this change was later observed for the shoots than roots.?5?The results of Fourier infrared spectroscopic analysis and Hg concentration in different tissues of Paspalum distichum.L's cytoderm demonstred that Hg mainly bound to hemicellulose 1?HC1?.However,the binding parts was changed to pectin when the iron plaque exsited.The amino and triple bonds in pectin are the major binding sites of Hg.In comparison,the carboxyl group was the major binding sites for HC1.