Studies On The Physiological Response Of Cyclosorus Acuminatus To Cu And Zn Pollution

As one of the effective ways with its low cost and environmental friendliness, the phytoremedition cansolve the problem of soil heavy metal pollution which is one of worldwide environmental problems. Thispapper discusses Cu (copper) and Zn (znic) pollution in soil though two single-factors and one complex-factors by pot experiments. The current study investigated the antioxidant systems, compartmentalizationeffects, leaf ultra-structure, accumulation, transportation and enrichment characterictic of the Cyclosorusacuminatus under Cu and Zn single and combined stress. The major results are summarized as follows:(1) When C. acuminatus was exposed to single copper or znic stress, with the heavy metal contentincreasing, the inhibition of root growths were enhanced. Chlorophyll contents also showed a downwardtrend, and the level of chlorophyll b decreased more significance than chlorophyll a. Under combined copperand znic stress, inhibition effects of root growth mainly reflected in mature roots. Both copper and znic hadsignificant stress effects in contents of chlorophyll a, while copper factor was more influential to chlorophyllb.(2) When C. acuminatus was exposed to single copper or znic stress, the antioxidant systems enhancedwith heavy metal contents and processing time. The contents of MDA (malondialdehyde) and SP (solubleprotein) increased with copper contents, while in the znic stress, MDA and SP showed a trend that increasedfirst and then decreased. In combined stress, copper had more significant effects in antioxidant systems thanthe znic factor, both copper and znic were the common factors in changes of MDA and SP.(3)When treated for28days, transportation and accumulation of C. acuminatus were positivelycorrelated with copper and znic contents. Bioaccumulation factor （BCF） and transfer factor（TF）forcopper positively related to metal contents, while BCF and TF for znic were negetivly correlated withmetal contents. Through TFs for both metals maintained a high level (＞1). The relationship oforganizational level was that roots contents were the highest, petioles followed, and finally were leavescontents. Under the composite treatments of copper and zinc, in leaf, petiole and root, copper uptaked amountand concentration was positively related, zinc absorption was also positively correlated with theconcentration. Under the composite processing of copper and zinc, C. acuminatus exhibitedcompartmentation phenomena. Heavy metal concentration was of the order of cell wall components, cytoplasmic component, and cell components, with more than50%of total accumulation occurring in cellwall and cytoplasm components. The compartmentation mechanism effectivly reduced the harm of heavymetal to plants.(4)When C. acuminatus exposed to copper and znic single stresses, the chloroplasts were twisted andextruded more and more seriously, plasmolysis phenomena became more and more clear, and density andcontents of cell wall decreased. Leaf ultra-structure showed a dose effect. Under the combined stress, cellstructure showed similar abnormal phenomenon, but, copper had a more serious effect on destruction of cellsthan zinc did.The results prove that C. acuminatus is a kind of ideal plant metarials to treat Cu and Zn single andcombined stress.