镉污染土壤对潜在能源植物生长的影响

利用重金属污染土壤种植能源植物是一种同时解决环境问题和能源问题的新理念,但目前相关研究成果并不多。通过盆栽试验研究人工镉污染土壤中象草Pennisetumpurpureum和亚香茅Cymbopogonnardus两种植物植株的生长状况和两种植物对土壤镉的吸收和富集能力。结果表明,当外源可溶性镉加入到土壤后,其主要是以生物有效性较高的状态存在。土壤镉对象草和亚香茅生长的影响作用有很大的不同,亚香茅比象草具有更强的镉耐受力,其生物量受镉污染影响小。两种植物植株镉含量均随土壤镉添加量的增加而增加。除高镉处理象草外,植物地下部分含镉量比地上部分高很多。高镉处理象草地下部分含镉量比地上部分低的现象可能反映出根系已积累了太多的镉,因而加速了向地上部的转移,从而加剧了植物中毒的程度。赤泥添加剂具有降低土壤酸度,减少植物对镉的吸收和增加象草和亚香茅生物量的作用。

Effects of soil cadmium on the growth of two potential energy plants

The use of heavy metal-contaminated soils for growing energy crops provides a possible solution to both environmental hazards and bio-energy production in the affected areas.Yet relevant research has been relatively limited.In this work,a pot experi-ment was conducted to examine the effects of soil Cd on the growth of two potential energy plants:napiergrass(Pennisetum pur-pureum)and nardus lemongrass(Cymbopogon nardus)and their capacity to extract Cd from the soils.The results show that soil Cd has differing effects on the growth of these two different plant species.Nardus lemongrass was more tolerant to Cd stress than napiergrass and its biomass was less affected by soil Cd contamination.There is a trend that Cd concentration in the tissues of both plants increased with increasing amount of Cd being added to the soil.Except for napiergrass in the high Cd treatments,Cd was higher in the underground portion than in the above-ground portion.The opposite observed for the high Cd-treated napiergrass re-flects that there was too much Cd accumulated in the roots which might caused accelerated translocation of Cd from the roots to the shoots,leading to stronger toxicity to the plant.Addition of red mud reduced soil acidity and Cd uptake by the plants and therefore enhanced the growth of the plants.