| For a long time, people have been irrationally exploiting heavy metal resources excessively, such as lead, zinc or other minerals,which inevitably caused much heavy metal pollution in the local environment, and further threat to crop developing,water quality and human health. Phytoremediation is an eco-friendly technology that could be used to restore heavy metal contaminated soils and sites with both economic and ecological benefit. While making use of the charcters of the weeds, for lage biomass, hardiness, rapid growth, can make up current phytoremediation for the deficiency ulteriorly, and promote further widely use of phytoremediation.In this paper, dominant plants form Lead-znic polluted farmland in Lead-zine mine of Hanyuan County, Sichuan Province are sampled and analyzed,and Selaginella pulvinata Maxim is found. Furthermore, accumulation characteristics and tolerance mechanism of S. pulvinata Maxim under the stress of Pb-Zn are studied with the pot experiment.The main results are summarized as follows:(1) The soil aroud the Lead-zine mine of Hanyuan County are polluted seriously, and the content of Lead and Zinc of soil in the tailings are much higher than other place.The total Lead content are222.40-1883.66mg/kg, the available Lead content are30.85-302.15mg/kg; The total Znic content are187.43-413.46mg/kg, the available Znic content are26.07-71.23mg/kg.(2) The research area has rich vegetation types, the content of Lead of14dominant plants in shoots and roots are6.95-672.10mg/kg and10.78-820.49mg/kg, respectively.the content of Znic of14dominant plants in shoots and roots are26.10-249.51mg/kg and13.06-260.62mg/kg, The content of Lead in shoots of Selaginella pulvinata Maxim is672.10mg/kg, and is the highest in the14dominant plants. The Pb translocation coefficients and bioconcentration coefficients of S. pulvinata Maxim are2.144、0.357and0.728; The content of Znic in shoots of S. pulvinata Maxim is249.51mg/kg.(3) The highest content of Lead in shoots and roots of S. pulvinata Maxim under the stress of Pb-Zn are1150.52mg/kg and539.53mg/kg, respectively. The highest content of Znic in shoots and roots of S. pulvinata Maxim under the stress of Pb-Zn are275.87mg/kg and273.15mg/kg, respectively. The highest Pb bioconcentration coefficients in shoots and roots of S. pulvinata Maxim under the stress of Pb-Zn are2.79and1.68, The highest Zn bioconcentration coefficients in shoots and roots of S. pulvinata Maxim under the stress of Pb-Zn are1.76and1.65, respectively.The highest Pb and Zn translocation coefficients of S. pulvinata Maxim under the stress of Pb-Zn are5.74and1.24. For the reason that, S. pulvinata Maxim is a Pb hyperaccumulators.(4) The leaves of S. pulvinata Maxim turn yellow and shriveled under the different concentration of Pb-Zn.The plants biomass of S. pulvinata Maxim under the stress of Pb-Zn are increased with the different concentration of Pb-Zn,but then reduced, and the maximum is11.81g/plant.(5) The total chlorophyll of S. pulvinata Maxim goes down with the climbing lead density, decreasing progressively, and its peak data is4.69mg/g.FW under the condition of CK(P0Z0).(6) The MDA concentration in the shoots is higher than it in roots of S. pulvinata Maxim in our experiment, and the average total amount goes high in different levels by the higher contentration of lead. The peak datas are respectively1.36μmol/g-FW and0.95μmol/g-FW under the condition of P4Z3and P4Z1.(7) The activity of SOD,POD and CAT in the shoots of S.pulvinata Maxim are all higher than those in the roots,and the total activity under the stress of Pb-Zn are increased with the different concentration of Pb-Zn,but then reduced, while the total activity in the roots has similar but faint pattern.(8) Soluble saccharide in the shoots are more than those in the roots, and the average total amount under the stress of Pb are increased with the different concentration of Pb-Zn,but then reduced.the peak datas are8.81mg·DW and5.12mg/g-DW relatively under the contion of P2Z3,and P1Z2.(9) The average total amount of soluble protein in the shoots and roots of S. pulvinata Maxim goes high and then goes down by the higher contentration of lead. The peak datas are0.14mg/g-FW and0.18mg/g-FW under the condition of P1Z2.This research shows that S. pulvinata Maxim can still grow robust under the stress of Lead and Zinc, which is to say, it has preferable tolerance and resistance; and that it has high Pb-Zn content, and other essential features of hyperaccumulators, belonging to lead hyperaccumulators. Therefore, this research provide a new material to remend and resotre heavy metal contaminated soils, and it could be used in very bad environment, putting up high practical advantage. |
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