Effects of Different Enhancing Agents on Extraction of Soil Heavy Metals by JUNCAO Lvzhou No.1
[Objective]The effects of different enhancers on the extraction of heavy metals from soil by the JUNCAO Lvzhou No.1 were studied to provide a reference for the remediation of heavy metal-contaminated soil and the safe utilization of the JUNCAO Lvzhou No.1.[Method]Taking the JUNCAO Lvzhou No.1 as the study object,the content of lead(Pb),cadmium(Cd)and arsenic(As)contaminated soil treated with seven different enhancing agents were investigated in pot experiments with no enhancer application as the control(CK).The seven enhancing agents were as follows:rhamnolipid(RHA),citric acid(CA),ethylenediamine disuccinic acid(EDDS),polyacrylic acid(PAA),polyacrylic acid grafted with humic acid(PAA-HA),2-diethylaminoethyl-3,4-dichlorophrylether(DCPTA),diethylaminoethyl-3,4-dichlorophrylether grafted with choline chloride(DCPTA-ChCl).The enrichment characteristics of Lvzhou No.1 to Pb,Cd,and As at different growth stages were also analyzed.[Result]DCPTA-ChCl and RHA showed promoting effects on the synthesis of plant nutrients of Lvzhou No.1,with a significant increase in the relative content of chlorophyll by 3.32 and 3.07,respectively,compared to CK,and an increase in nitrogen content by 1.15 mg/g and 1.05 mg/g,respectively.PAA showed an inhibitory effect,with a significant decrease in the relative content of chlorophyll by 5.98,and a significant decrease in nitrogen content by 1.65 mg/g compared to CK.The content of Pb,Cd,and As in the above-ground parts of Lvzhou No.1 treated with DCPTA,RHA,and CA increased by 25.7%to 37.7%,54.3%to 55.6%,and 35.0%to 56.4%,respectively,compared to CK.Compared with CK,DCPTA-ChCl promoted the enrichment of Cd and As in Lvzhou No.1;DCPTA significantly promoted the enrichment of Pb and Cd;PAA significantly promoted the enrichment of As,but not Pb,and showed an inhibitory effect on the enrichment of Cd;PAA-HA significantly promoted the enrichment of Pb and As,but not Cd;EDDS had no significant effect on the enrichment of Pb,Cd,and As in Lvzhou No.1.From May to September,the content of Pb,Cd,and As in the stems and leaves of Lvzhou No.1 showed an increasing trend with time and with a larger increase;From September to December,the increase was smaller.Throughout the entire growth stage,the content of Pb,Cd,and As in the leaves was higher than in the stems,with Pb＞As＞Cd in the leaves,and the content of Pb and Cd in the stems was similar in May,June,and July,which were all greater than As,with Pb＞Cd＞As from August to December.[Conclusion]Adding DCPTA at 0.5 mg per plant,RHA at 2 mmol/kg,and CA at 2 mmol/kg can effectively promote the enrichment of Pb,Cd,and As in Lvzhou No.1,thereby enhancing its ability to remediate Pb,Cd,and As contaminated soil.At the end of June,the content of Pb in the stems and leaves of harvesting Lvzhou No.1 is 0.445 mg/kg and 4.57 mg/kg,Cd is 0.405 mg/kg and 0.537 mg/kg,and As is 0.128 mg/kg and 1.329 mg/kg,respectively,all of which are less than the limits set by Hygienical Standard for Feeds(GB 13078-2017),indicating that it is suitable for forage in animal husbandry.After July,the content of Cd in the leaves of harvesting Lvzhou No.1 exceeded 1 mg/kg,which is above the hygienical standard for feeds and not suitable for forage.Its application in fields such as composite materials and biomass energy can be explored.
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