Ultrastructure, Morphological Character And Phytoremediation Efficency Of Arsenci Hyperaccumulators

Arsenic contamination and exposure, because of its toxicity ,and carcinogenicity, caused great concern. However, the hazard of soil arsenic contamination, which usually fails to notice and consider, has not became an important environmental issue. Conventional technology has not adapted to remediated arsenic contaminated soil effectively and economically. Phytoremediation of As-contaminated soils with arsenic hypteraccumulator - Pteris vittata L. has been considered to be an economic, fast and little secondary contaminative new remedial technology. In order to pick out the right plants (groups) which can be apply to phytoremediation of As-contaminated farmlands, arsenic in plants and potential risk for human from As-contaminated farmlands in Chenzhou city, Hunan province were assessed, and ultrastructure and morphological character change of arsenic hyperaccumulators after arsenic treatment have been researched.1.Revegetation in As-contaminated soil was significantly affected by contaminated grade, The main factor for controlling the species diversity in the soil was growth of Paspalum sp., a dominated weed. As concentration in edible part of most vegetables exceed the maximal permissible limit. Intake of arsenic from consuming vegetables exceeded the standard (2.1 ng/kg body wt. per day) set by WHO.2.Comparative test of four different plants on As-contaminated farmland, the results showed: hyperaccumulator - P. vittata is the one which adapt to apply to phytoremediation; both remedial efficiency of tolerant plants Miscanthus floridulu Warb. and Boehmeria nivea (L.) Gaud, far lower than P. vittata's, so these two kinds tolerant plants are not fit to apply to phytoremediation; arsenic biotic pyramid of the industrial commercial crop Ricinus communis L. is the lowest one ,and it's crop outputwas very low.3.Ploidies of P. vittata come from three areas have been analyzed, and the results show that they are different. As-accumulate capability trend of different ploidy is: diploid>triploid>tetraploid. Growth and development of P. vittata's gametophyte was significantly affected by arsenic concentration: they can be promoted by the low concentration and be inhibited by high concentration, and the inhibition can be strengthening by lifting of arsenic concentration.4.Ultrastructure character change of leaf after different arsenic and calcium concentration treatment have been research, the results show that structure of P. vittata's chloroplast can be damaged by the high calcium concentration, and P. vittata have the high tolerance to arsenic and calcium. Add proper quantities calcium can lighten arsenic menace to chloroplast and mitochondria of Pteris nevosa. Research of the Ca2+ distribution in cell show that high concentration calcium makes menace to P. vittata, which can adjust itself under high arsenic menace. Calcium maybe related to the arsenic antidotal action of P. nevosa.