Research On The Enrichment Rule,Tolerance And Repairing Effect Of The Kalanchoe Daigremontiana On Lead And Zinc

After the lead-zinc mine has been mined,the drainage and tailings accumulation in the mining area have caused serious heavy metal pollution to the water and soil in the basin,and endangered the life and production activities of the residents near the mining area.Phytoremediation is a clean technology that can transfer pollutants such as heavy metals in water or soil to plants.Crassulaceae plants have broad prospects and advantages in remediating heavy metal pollution,and have a good absorption effect on heavy metals,for example,Sedum alfredii Hance is a hyperaccumulator of cadmium and zinc,and Sedum plumbizincicola is a hyperaccumulator of cadmium.Kalanchoe daigremontiana is a perennial succulent herb belonging to the genus Galenia of Crassulaceae.It has the advantages of asexual reproduction and short growth cycle,and has great potential in ecological restoration.In this paper,the lead and zinc pollution hydroponic experiments and the lead-zinc composite pollution soil culture experiments were used to explore the enrichment rules,physiological responses,tolerance and repair effects of Kalanchoe daigremontiana plants on lead and zinc under different conditions,provide theoretical basis for repairing lead-zinc mines.The main findings of the study are as follows:1.In the hydroponic and soil culture experiments,the enrichment rules of lead in different parts of the two experimental plants are: root>stem>leaf;the enrichment rules of zinc in different parts of the two experimental plants have two situations: 1)roots >stem>leaf,all appeared in the early stage of the two experiments;2)Root>leaf>stem,all appeared in the middle and late stage of the two experiments.The transport coefficient(TF)of lead in both experiments was less than 1,and the TF of lead in the soil cultured with lead-zinc composite pollution was greater than that in the hydroponic culture,indicating that the presence of zinc was beneficial to the transport of lead in the large-leaf and rooting plants.The enrichment factor(BCF)of the low concentration of lead(10mg/L hydroponics)is greater than 1;the enrichment factor(BCF)of the low concentration of zinc(10mg/L,30mg/L hydroponics)is greater than 1,indicating that the plants are not sensitive to medium and low concentrations Lead and zinc have better enrichment effect.2.In the soil culture experiment,the chlorophyll and carotenoid content of plant leaves decreased significantly with the increase of lead and zinc concentration in the early stage of the experiment(P<0.05),and there was no significant difference between different concentrations in the middle and later stages of the experiment.In the early stage of the experiment,the content of malondialdehyde(MDA)increased significantly with the increase of lead and zinc concentration(P<0.05),and there was no significant difference under different concentrations in the middle and late stages of the experiment,indicating that plants have a certain tolerance under adversity.In the hydroponic experiment,chlorophyll and carotenoids were negatively correlated with the concentrations of lead and zinc in the solution,and the content of malondialdehyde was positively correlated.3.In the soil culture experiment,the plants were greatly affected by lead and zinc in the early stage of growth.The leaf length,root length,stem length and fresh weight of the experimental groups with different concentrations decreased significantly with the increase of soil lead and zinc concentration(P<0.05).There were no significant differences in leaf length,root length,stem length and fresh weight of plants in the middle and late stages of the experiment,indicating that plants had a certain tolerance to lead and zinc stress after adapting to the environment.4.In the soil culture experiment,the removal rate of large-leafed rooting plants after enriching zinc in the soil reached a maximum of 32.88%,and the removal rate of lead enrichment in the soil reached a maximum of 18.77%.In the hydroponic experiment,the maximum removal rates of lead and zinc in the culture solution were 25.10% and 27.09%,respectively.It is proved that the Kalanchoe daigremontiana have the actual repair effect on the soil contaminated by composite lead and zinc,and have the enrichment effect on lead and zinc in the water body,and have a good adsorption effect on zinc at medium and low concentrations.5.In the soil culture experiment,there is a positive correlation between the zinc enrichment in the aerial part of the plant and the relative water content of the plant.Under the same culture condition,the aboveground zinc content is also higher when the relative water content of the plant is high.