Enrichment Process And Mechanism Of Arsenic In Pteris Vittata Around Lead-Zinc Mining Area

With the development and utilization of mineral resources,arsenic pollution caused by mining is becoming more and more serious.The arsenic in the soil from mining can enter the human body through the food chain,which is harmful to human health.Therefore,the soil arsenic pollution control appears very important.The discovery of arsenic hyperaccumulator plant Pteris vittata provides a new idea for the treatment of arsenic contamination in soils.Studying on the mechanism of arsenic hyperaccumulator Pteris vittata can provide a theoretical basis for phytoremediation of arsenic contaminated soil.This paper takes Pteris vittata,Bracken,Cyclosorus parasiticus,dicranopteris pedata in Yunnan lead zinc mining area and the growth environment as the research medium.The pollution problem in mining area was investigated.Besides,aiming at the current problems that the location AsV reduction to AsIII is unclear in Pteris vittata,and the problems that the mechanism of arsenic detoxification of Pteris vittata is unknown,this paper experiments on micro area,speciation and subcellular extraction.XRF experiments focused on the microdistribution of As and K,Mn,Fe,Cu,Zn and S.XANES experiments put emphasis on the speciation of As in rhizome,stem and leaf of Pteris vittata.Through subcellular extraction experiments,the speciation of As at the subcellular level in the rhizome,stems and leaves of Pteris vittata was analyzed.Detailed conclusions are listed below:(1)The content of arsenic in the surveyed soil exceeded the standard,and the most serious pollution was 10.08 times that of the national three grade quality standard.(2)This study also confirms that the Cyclosorus parasiticus and dicranopteris pedata are not hyperaccumulator via accumulation of As in plants and bioaccumulation factor of plants to As.(3)Micro area XRF results show that the micro area distribution of As and K,Mn,Fe,Cu,Zn,S in Pteris vittata's whole seedlings is similarity.In the fronds,the balance of anion and cation in plant perhaps can explain the similarity of distribution between As and K,Mn,Fe,Cu,Zn.The similarity between As and S indicates that PCs plays a very important role in Pteris vittata.(4)The speciation analysis with XANES shows that the main location AsV is conversioned to AsIII in Pteris vittata is root.(5)The experimental results of subcellular distribution suggests that the As combination with hydrophobic protein in fronds is as little as 2.4% and arsenic is mainly stored in vacuoles in the fronds.