The Analysis Of Microbial Population In The Rhizosphere And Potassium And Calcium During The Prossess Of As-accumulation By Pteris Vittata

Heavy metals contamination of soil poses a major environmental and human health problem, which is still in need of effective and affordable remediation. Phytoremediation, a low cost alternative to traditional contaminant physical and chemical removal/disposal techniques. This technique uses hyperacumulator plants that have the ability to accumulate very high metal concentrations from contaminated soil in their shoots. Hyperacumulator plants are the basis and premise of phytoremediaton. The rhizosphere provides a complex and dynamic microenvironment where microorganisms, in association whit roots, form unique communities. A number of researchers have reported that some microbes that were in rhizosphere of hyperaccumulators such as Zn-accumulating plant Thlaspi caerulescens, Ni-accumulating Alyssum murale and so on, were able to increase heavy metals accumulation by hyeraccumulators. These research suggested that not only phytoremediation depended on accumulation capabilities of hyperaccumulators, but also rhizomicrobes played an important role in phytoremediation. However, considerably less information is available on rhizomicrobial processes and characteristics of hyperaccumulators. Brake fern {Pteris vittata L.) is the first kind of hyperaccumulator discovered by our nation's scientists. The discovery of Pteris vittata offers the feasibility for phytoremediation of As-contaminated soil. Potassium and calcium are all necessary elements to plants. They play an important role in growth and development of plants. Some reports have revealed that arsenic was compartmentalized mainly in the upper and lower epidermal cells, probably in the vacuoles. Arsenic and potassium have similar distribution in the fronds of hyperaccumulator P. vittata. Their distributing characteristics have prominent relevance. The distribution of calcium was different from the distribution of arsenic in fronds. The avaiable information, however, about the correlations of contents between potassium, calcium and arsenic in fronts of Pteris vittata is less.The first phytoremediation demonstration base of As-contaminated soil in Chenzhou city, Hunan Province, was founded by The Environmental Remediation Center in Institute of Geographical Sciences and Natural Resources Research, CAS. This study was caught out in the phytoremediation base. The changing characteristics of microbial populations in rhizosphere of Pteris vittata and the correlations between potassium, calcium and arsenic content in buck soil and fronts of Pteris vittata growing phytoremediation was studed. In addition, the balance of potassium and calcium in phytoremediation base soil was analysed. It will be helpful to reasonably apply fertilizer, supplement the losses of potassium and calcium in right time, guarantee the equilibrium of the soil potassium and calcium, imcrease the efficiency of phytoremediation.Analysis of microbial pollutions in rhizosphereThe analysis of microbial populations in the rhizosphere of P. vittata demonstrated that the number of bacteria was significantly higher than ones of actinomycetes and fungi, and the number variation of bacteria was most significant. Bacterial ratioes of number of rhizomicrobe to number of...