Two Types Of Repair Agent Effect On The Translocation And Accumulation Of Copper In Amaranthus Retroflexus L.System

Copper is environmental pollution of heavy metal,but also one of the necessary trace elements in plant growth and development.Copper with the production of human life was discharged into the environment and accumulated in water and soil.The biological remediation of heavy metal contaminated soil is a key problem the prevention and control of environmental pollution.Phytoremediation is an in situ remediation technology,has little effect on soil structure and microorganisms,and has the characteristics of the economy,the current and adding a chelating agent,chemical remediation methods of exogenous organic acids combined used in the repair of heavy metal pollution.Biochars as a new material repair soil pollution.Pot experiments were conducted to study the effects of biochar,ethylene diamine tetraacetic acid?EDTA?and citric acid?CA?on copper accumulation and translocation in Amaranthus retroflexus L.,with exogenous copper concentrations of 0,100,200,400 and 800 mg·kg^-1.We determined the soil physical and chemical properties,Cu chemical forms,Amaranthus retroflexus growth indicator and tissue Cu concentration in contaminated soil under by applying biocar.The major sesults obtained were summarized as follow:?1?Willow branch were used to prepare biochar using 400 ?oxygen-limited pyrolysis method.The results showed that the biochar had rich specific surface area,high porosity and rich surface functional groups.Biochar has very high adsorption capacity of Cu²⁺ and the Langmuir equation can describe the biomass carbon of Cu²⁺ adsorption effect very well.pH is an important factor affecting the adsorption of biochar.The adsorption of Cu²⁺ on the biochar included electrostatic and non electrostatic adsorption.The pseudo two order kinetic equation can describe the adsorption kinetics of Cu²⁺,which indicated that the adsorption fo biochar including physical adsorption and chemical adsorption.?2?We adopt the pot experiment to understand the influence of the biochar?BC?in the migration of Cu in soil-Amaranthus retroflexus system.The results showed that the biomass charcoal can significantly increase the soil pH,organic matter content and cation exchange capacity;Greatly reduced the soil bioavaility state,including exchangeable state?Exch?and carbonate state?Carb?,and increased iron and manganese oxidation state?Fe,Mn?ratio,with Cu in the soil-crop system excessive enrichment of blocking effect,and significantly improve survival rates Amaranthus retroflexus and biomass,increase average of 30%.Adding 10 mg·kg^-1 after the biomass carbon,Amaranthus retroflexus root,stem and leaf Cu content were significantly reduced,the biggest drop in root,stem and leaf were 78%,67%and 52%,respectively,can be guaranteed in soil Cu content is less than 100 mg·kg^-1 of security.Biomass carbon is abundant in raw materials,can slow down the greenhouse effect,and can effectively block the enrichment of heavy metals in the food chain,has applied to the soil pollution repair prospects.?3?Pot experiments were conducted to study the effects of ethylene diamine tetraacetic acid?EDTA?and citric acid?CA?on copper accumulation and translocation in Amaranthus retroflexus L.The concentrations of Cu with different speciations in both rhizosphere and bulk soil,and its enrichment characteristics in plant tissue were determined after adding 2.5 mmol·kg^-1 CA or EDTA to different copper treatment.Results showed that the ability of copper accumulation in different plant tissues followed the sequence of roots>leaves>stems when copper contents were less than 400 mg·kg^-1,while roots>stems>leaves when copper contents were 400 mg·kg^-1.BCFs and TFs of A.retroflexus were both less than 1,which indicated that A.retroflexus was not a copper hyperaccumulation plant under the present experiment condition.Both EDTA and CA can effectively improve enrichment ability of the plant for copper and enhance the transportation of copper from roots to shoots;EDTA was more effective,causing 3512.71 mg·kg^-1 of shoots uptake under the 800 mg·kg^-1 copper content condition.The contents of total copper and exchangeable speciation inrhizosphere soil were increased for the EDTA amendment,while the content of Fe-Mn oxidizable speciation of copper decreased.The addition of CA promoted the chemical conversion of copper from Fe-Mn oxidizable speciation to carbonate speciation in rhizoshpere soil.It concluded that EDTA significantly improved the copper uptake of A.retroflexus and increased the content of total copper in rhizosphere soil,which resulted from the joint effects of the increasing migration activity of Cu-EDTA and the copper exclusion mechanisms of A.retroflexus.