植物根部对铅的富集及其固铅作用的研究

本文以含Pb2+的水溶液培养植物,使其根部富集重金属铅,然后分析比较富集铅前后植物根部元素及其含量变化,由此推测可能参与固铅的物种,并通过模拟沉降固着和吸附实验进行验证.结果显示:所选植物长药景天(Hylotelephium spectabile(Bor.)H.Ohba)在加铅总量为80 mg的200 mL水溶液中培养4周后,其根部铅含量可高达30.18×103mg/kg,而叶片中的铅含量很低;其根部在含铅离子的蒸馏水培养液中的固铅量最大,在不同培养液中其根部固铅量的递减顺序为:蒸馏水培养液(D)>无磷培养液(B)>基础培养液(A)>无硫培养液(C);植株根部随着铅的富集,钙和磷的含量都有一定的增加.通过模拟沉降固着和吸附实验证实植物根部是通过形成铅的磷酸盐来固定铅的,钙的存在有助于加快铅的固着.

Accumulation and fixation of lead by plants' roots

In order to find out the key species possessing a strong fixation of heavy metals and the relevant species assisting in the fixation,a novel method was proposed that plants were cultivated in a heavy-metal-containing aqueous solution,their roots’ were compelled to accumulate the heavy metals,and then the chemical elements and their content in the roots were analyzed.And sedimentation and adsorption experiments were followed to confirm the speculated species.According to this method,the investigation of fixation of lead by plant’s roots was made.The results showed that after 4-week exposure to 200 mL of lead-containing aqueous solution(containing a total amount of 80 mg of Pb2+),an accumulation of lead in a tested plant’s roots(Hylotelephium spectabile(Bor.) H.Ohba) was as high as 30.18×103mg·kg-1,and,on the contrary,almost no lead was detected in the plant’ leaves.In terms of fixation amount of lead by the roots in different solution,the descending order in terms of the amount of lead fixation was: in distilled water(D)> in phosphate-free medium(B)> in basic culture medium(A)> in sulfur-free medium(C).It is observed that the contents of phosphorus and calcium were increased as lead in plant’s roots was accumulated.By sedimentation and adsorption experiments,it is confirmed that the fixation of lead by plant’s roots are via the formation of lead phosphate,and the presence of calcium can accelerate this process.