Study On Screening Of Tolerance To Kenaf And Jute Under Improved Lead-Zinc Slag And Preliminary Research On Tolerance Mechanism

In view of the low biomass,low economic value,and secondary pollution of most hyperaccumulators in phytoremediation,30 kenaf and jute varieties with large biomass and certain economic value were selected as lead-zinc slag-resistance for this project.Plant screening objects,preliminary screening of tolerance plants and their mechanisms.An outdoor pot experiment was conducted with peat soil as the improver(control:0,improved group 1:10%,improved group 2:20%),and the plant survival,biomass,and Pb,Zn content and absorption in various parts of the plant were studied.The characteristics were analyzed in order to screen out the plant species that could be used in the rehabilitation of abandoned mine sites.Then,the relationship between the characteristics of Pb and Zn subcellular distribution and chemical forms and the mechanism of tolerance was explored.To provide technical reference for the treatment of heavy metal pollution in lead-zinc mines.The main results of the study are as follows:(1)Preliminary screening of kenaf and jute under improved lead-zinc slag.30 kenaf and jute varieties can survive under the improvement of lead-zinc slag exceptfor 2,4,6,7 and 25,indicating that kenaf and jute had certain tolerance to high lead and zinc combined stress.The biomass growth rate of kenaf and jute ranged from 3%to 720%,indicating that the application of modifier peat soil increased plant biomass.Different varieties of hemp have certain adsorption ability to Pb and Zn but the absorption and accumulation of different heavy metals in different varieties of plants are quite different.Under each treatment,the contents of heavy metals in all parts of the plant were larger than those in the control group,except for the content of zn in the aboveground part of the plant,and mainly accumulated in the root of the plant.From the analysis of two factors,plant biomass,Pb and Zn in Kenaf and jute in all parts of the enrichment and distribution of the varieties(P<0.01),adding peat(P<0.01)and the interaction between the two(P<0.01)significantly affect the effect,which is mainly affected by varieties of peat soil,and the influence of the amount of peat soil added was secondary.(2)Optimization and screening of kenaf tolerant plants with improved lead-zincslag.Due to the small biomass harvested in the first year,it is possible that the heavy metal content in the substrate is too high.In the second year,the proportion of peat soil was adjusted to 0,15%and 30%,and according to the first year plantthe average membership function values for Pb and Zn accumulations were selectedand the top 10 plants were selected for further testing.The biomass of plants harvested in the second year was mostly higher than the first year.Under the improved two treatment,the average biomass of the aboveground and underground part was 23.06 g and 10.79 g,and the heavy metal accumulation also increased.Analyzing the plant heavy metal accumulation and transfer coefficient,it was found that the plant's ability to enrich and transport Zn is stronger than that of Pb,which may be because Zn is an essential element for plant growth.The content of heavy metals in the substrate after harvest was lower than before.The average removal rates of Pb in control,improved one,and improved two treatments were 7.49%,6.93%,and 7.58%,respectively,and the average removal rates of Zn were 6.19%,10.65%,and 14.76%,respectively.Among them,No.19 and No.30 plant have higher Pb and Zn removal rates.Based on the average membership function values of Pb and Zn in the plants under each substrate,10 varieties selected in the first year were classified into high,medium and low Pb and Zn accumulation types by cluster analysis.(3)Pb in kenaf is mainly distributed in the cell wall,accounting for 32%to 82%of the total,Zn is mainly distributed in cell walls and cell fluids,the compartmentalization of heavy metals by cell walls and vacuoles is one of the heavy metalmechanisms of Kenaf,Pb is mainly present in the leaves and roots of plants with the deionized water and sodium chloride extracts.The stems are mainly extracted with acetic acid.Zn was mainly extracted by ethanol and sodium chloride in the leaves.The stem was mainly extracted by sodium chloride,while the root was mainly extracted by acetic acid.Pb and Zn mainly exist in the weak activity of sodium chloride and acetic acid in the roots of plants,which may be an important mechanism of tolerance to Pb and Zn in theroots of plants.