Vetiveia ZizanoidesAdaptability Of Lead-zinc Mine Tailings On The Growth Under Different Treatments

The exploitation of mineral resources not only destroys the ecological environment but also brings serious heavy metal pollution.Because of its advantages of low investment,no damage to the site structure,and no secondary pollution,phytoremediation is increasingly becoming an important treatment technology for the repair and reconstruction of heavy metal contaminated soil.Vetiveia zizanoides is a perennial grassy herb with enrichment for heavy metals,and it has the characteristics of large biomass,long growing period,multiple castration and strong adaptability.The adaptability of growth on mine tailings is of great significance for the rapid restoration of vegetation using tailings of vetiver.In this paper,the growth adaptability of lead-zinc mine tailings under different treatments was studied.The experiment consisted of four treatments:(1)lead-zinc tailings(LT);2)lead-zinc tailings + compound fertilizer(LTC);(3)pure lead-zinc mine tailings +humus and NPK compound fertilizer(lead-zinc tailings + humus + compound fertilizer:LTHC)(4)Normal zonal red soil(CK),with 5 replicates per sample design.In this study,the determination of chemical properties of tailings,soil and matrix,as well as the analysis of the growth characteristics and physiological characteristics of vetiver plants in lead-zinc mine tailings,and the determination of the absorption characteristics of heavy metals,the soil Based on the difference of chemical properties of tailings,the effects of different treatments on the culture,growth and physiological characteristics of vanilla root plants,the absorption characteristics of heavy metals,and the interaction between vanilla root growth adaptability and environmental factors were discussed.Mechanism,finally comprehensive evaluation of the adaptability of vanilla roots under different treatments,so as to screen out the best treatment measures to alleviate the effects of lead-zinc mine tailings on the growth of vanilla roots,and obtain the following important conclusions;(1)There is a very significant difference between the soil chemical properties oflead-zinc mine tailings and red soil samples.The soil pH,organic matter,total nitrogen,total phosphorus and total potassium in red soil samples were significantly higher thanthose in lead-zinc mine tailings.The contents of heavy metals Cd,Pb,Zn and Cu inlead-zinc mine tailings were significantly higher than those in control red soil.Comparedwith normal soil,the tail soil has lower soil fertility and higher heavy metal content.(2)The contents of pH,organic matter,total nitrogen,total phosphorus and total potassium in the three treatments of LTC,LTHC and CK were significantly higher than those of LT pure lead-zinc mine tailings;and LT pure lead-zinc mine tailings The contents of heavy metals such as Cd,Pb,Zn and Cu were significantly higher than those of the other three treatments.It shows that the use of NPK compound fertilizer can effectively improve soil fertility,but it can not improve the problem of excessive heavy metal content in lead-zinc mine tailings.(3)The plant height,tiller number and biomass of four groups of vetiver were determined in different growth stages,and the order was:CK>LTHC>LTC>LT.It indicated that the growth of vetiver on pure tailings was inhibited by heavy metals.Although all physiological processes could be completed,the growth was poor.After adding NPK fertilizer,the growth of vetiver grass was promoted,but the effect was not significant.After adding NPK fertilizer and humus,vetiver grows vigorously,and the indexes such as plant height,tiller number and growth rate are close to those of normal soil vetiver.(4)The photosynthesis rate,transpiration rate and the resistance index of vetiver to heavy metals in LTHC treatment were significantly increased and close to normal soil levels.The content of soluble protein,superoxide dismutase(SOD)and malondialdehyde(MDA)under LT treatment were higher than other treatments,and the content in CK treatment was the lowest.The physiological body type of vetiver showed:LTHC>LTC>LT>CK,indicating that vetiver planting on tailings can promote its growth by applying NPK fertilizer,especially after adding humus,the adaptability of vetiver is significantly enhanced...(5)Among the four different treatments,the concentrations of Cd,Zn and Pb in the roots were higher than those in the leaves,indicating that the roots of vetiver had stronger enrichment ability for Cd,Zn and Pb.From the indicators of transport coefficient and retention rate,it can be seen that vetiver has certain migration,transport and enrichment ability to Cd,Zn and Pb.It is a pioneer plant suitable for repairing heavy metal contaminated soil,especially after adding humus to fragrant root.The enrichment and absorption characteristics of grass are obviously affected,and the heavy metals are more partially migrated to the vetiver grass.(6)The comprehensive evaluation values of vetiver for the growth of lead-zinc mine tailings were significantly different under the four treatments.Among them,CK treatment was significantly higher than LTHC treatment,LTHC treatment was significantly higher than LTC treatment,and LTC treatment was significantly higher.Processing in LT.Compared with the LT treatment,the comprehensive evaluation values of the other three treatments of vetiver on the growth of lead-zinc mine tailings increased by 20.1%,113.58%and 171.66%,and the order of the evaluation values was:CK(94.34)%)>LTHC(74.17%)>LTC(41.67%)>LT(34.73%).It indicated that the addition of NPK fertilizer and humus could effectively alleviate the growth adaptability of vetiver plants to lead-zinc mine tailings.This treatment can be used as the best way to grow vetiver in lead-zinc mine tailings.In summary,different treatments can significantly affect the chemical properties of the substrate and the adaptability of vetiver plant growth.The addition of NPK fertilizer and humus is the closest to the soil,and the effect is most significant.Therefore,in the process of phytoremediation of vetiver plants in the lead-zinc mine tailings area,the treatment of adding NPK fertilizer and humus should be selected as much as possible to provide a theoretical basis for improving the environment of the mining area.