| In the current study,more and more herbaceous plants were used in phytoremediation,but there were some deficiencies about herbs, such as small biomass, low utilization, secondary pollution problem and other issues. In this research,4categories of native plants in Hunan province including industrial raw materials plants, timber plants, landscape plants and energy plants were choosed as experimental plants to screen for tolerant plants in lead-zinc mining area and explore the tolerance mechanism of these plants. A pot experiment was conducted by using18species plants and improved lead-zinc slag in Hunan Zixing for plants screening, the treatments were as follows:1) Control group:100%lead-zinc slag,2)Improved group1:85%lead-zinc slag+10%peat soil+5%organic manure;3)Improved group2:75%lead-zinc slag+20%peat soil+5%organic fertilizer. The growth condition, biomass, plant height, chlorophyll concentration, heavy metals content, accumulation characteristics of heavy metals were analyzed. The aim is to select lead-zinc tolerant plants and explore the relationship between chemical forms of heavy metals in plants, subcellular distribution and tolerance mechanisms.The object is to provide technical reference for the treatment of heavy metal pollution in lead-zinc mining area. The research results are as follows:(1) After7months cultivation (March to September,2013),except for pinus massoniana, Castanopsis fissa and Daphniphyllum calycinum, the other15species of experimental plants were survived,including Nerium indicum, Koelreuteria paniculata, Hibiscus syriacus, paulownia, Cunninghamia, Cinnamomum camphora, Salix matsudana, Populus，Swida wilsoniana, Sapium sebiferum, Acer elegantulum Fang, Cor chorus capsularis,Ricinus communis,Hibiscus cannabinus and Boehmeria nivea.(2) The plant growth condition were as follows:in control group, plants growth is slowly, shorter and with low biomass, while the plant biomass and plant height were improved obviously in improved treatments. Differencees of plant height were showed in different plant species. However, plant heights of all species were showed Control group<improved group1<improved group2,the most obvious difference of plant height were Hibiscus cannabinus and Corchorus capsularis in improved group2,, respectively which increased230cm and220cm,and the plant height of Hibiscus cannabinus in improved group2is more than330cm. The biomass change trends of most plants are similar to plant height, showed Control group<improved group1<improved group2, and the dry weight of Corchorus capsularis in improved group2was the highest in all plants which had reached180.2g. The rule of chlorophyll in plants in improved groups were group2> group1.(3)The uptake and accumulation characteristics of heavy metals in plants:Heavy metal concentrations of most plants showed Control group> Improved group1> Improved group2. The highest concentrations of Pb, Zn, Cu, Cd in plants aboveground parts were Boehmeria nivea (142.2mg/kg, Improved group2), Cunninghamia (514.8mg/kg, in Control group), Paulownia (21.28mg/kg, in Control group) and Hibiscus cannabinus (69mg/kg, in Control group). The heavy metal concentration, biological concentration factor (BCF) and translocation factor (TF) were not reach the critical values of hyperaccumulators. The uptake of heavy metals in plants showed a significant difference in different heavy metal type and plant species.(4)The heavy metal cumulant of plants:considering the impact of biomass, heavy metal cumulant in most plants showed opposite variation trend with concentration:Control group<improved group1<improved group2. The highest total accumulation amounts of Pb, Zn, Cu and Cd in plant aboveground were: Hibiscus cannabinus (2.70mg, in Improved group2), Salix matsudana (25.62mg, in Improved group2), Salix matsudana (0.44mg,in Improved group2), Populus (1.78mg, in Improved group2). Therefore, the biomass showed high correlation with heavy metal accumulation cumulant, we could screening large biomass plants to compensate for the deficiency of heavy metal concentration in plants.(5) Chemical forms of heavy metals in plants were different in different plant species,heavy metal kinds and concentrations. Ethanol-extractable and Hcl-extractable Zn were predominated forms in Paulownia and Nerium indicum. The distribution of Zn is different in different cell compositions and Zn mainly located in the cell wall fractions and the soluble parts, cell wall plays an important role in plant tolerance to heavy metal stress. |
PDF Full Text Request