锰矿修复区泡桐与栾树生长与重金属积累特性

在湘潭锰矿废弃地种植泡桐和栾树,建立了4hm²生态修复示范区.工程区基质Mn平均含量高达20041mg/kg,Pb、Zn、Cu、Cd含量也远超过湖南省和全国的背景值,属复合型重度污染.污染区不覆土,苗木移植前每株根际定量施用了含有自污染区矿渣分离出的抗性菌株的专用有机肥.种植两年后,泡桐和栾树成活率均达到83%以上.泡桐生长状况明显优于栾树,两种植物叶的重金属含量均大于根和茎,泡桐Mn、Cu、Zn的浓度和积累量显著高于栾树.5年生泡桐Mn积累量达到2295g/hm²,转运量系数为2.32.试验证明,采用有机菌肥改良根际环境后,泡桐与栾树均可作为锰污染区的修复树种,而泡桐的生长速率和重金属的耐受和积累性能优于栾树.

Growth and heavy metal accumulation of Paulownia fortunei and Koelreuteria bipinnata in an ecological restoration site of the manganese-ore tailing

A four hectare ecological restoration plot using wood species P. fortunei and K. bipinnata as phytoremediation plants was established in the Xiangtan manganese-ore tailing. The total average content of Mn at the project site was 20041mg/kg. The total average contents of Pb, Zn, Cu and Cd at the site were also much higher than the background values of Hunan province and China, showing a high level of multiple heavy metal contamination. The metal contaminated site was not sealed with normal soil. Before transplanting the seedlings, the rooting areas of the wood species at the experimental site were amended with organic manure containing a tolerant bacterium strain isolated from the mining wastes. In the second year after transplanting, the survival rates of both P. fortunei and K. bipinnata were higher than 83%. Species P. fortunei had apparently a higher growth rate than K. bipinnata. The contents of all measured metal elements were higher in leaves than in roots and stems of both species. The contents and uptake of Mn, Cu and Zn of P. fortunei were significantly higher than those of K. bipinnata. The total manganese uptake of five years old P. fortunei reached 2295g/hm²with a quantity transfer coefficient (the ratio of above to below ground uptake) of 2.32. In combination with the application of organic manure to improve the root growth environment, both P. fortunei and K. bipinnata could be used as phytoremediation tree species for manganese contaminated soil. In comparison, P. fortunei was superior to K. bipinnata as accounted for by their growth rates and nature in metal tolerance and uptake.