In order to investigate plant reacting mechanism with heavy metal stress in organ and tissue level ,synchrotron radia-tion micro X-ray fluorescence(μ-SRXRF) was used to determine element distribution characteristics of K ,Ca ,Mn ,Fe ,Cu ,Zn , Pb in an Arabidopsis thaliana seedling grown in tailing dam soil taken from a lead-zinc mine exploration area. The results showed a regular distribution characters of K ,Ca ,Fe ,Cu and Zn ,while Pb appeared not only in root ,but also in a leaf bud which was beyond previously understanding that Pb mainly appeared in plant root. Pb competed with Mn in the distribution of the whole seedling. Pb may cause the increase of oxidative stress in root and leaf bud ,and restrict Mn absorption and utilization which ex-plained the phenomenon of seedling death in this tailing damp soil. Speciation of Pb in Arabidopsis thaliana and tailing damp rhi-zosphere soil were also presented after using PbL3 micro X-ray absorption near edge structure(μ-XANES). By comparison of PbL3 XANES peak shape and peak position between standard samples and rhizosphere soil sample ,it was demonstrated that the tailing dampsoilwasmainlyformedbyamorphousformslikePbO(64.2% ),Pb(OH)2(28.8% )andPb3O4(6.3% )ratherthanmineral or organic Pb speciations. The low plant bioavailability of Pb demonstrated a further research focusing on Pb absorption and spe-ciation conversion is needed ,especially the role of dissolve organic matter in soil which may enhance Pb bioavailability.%为了从组织和器官水平研究植物在铅锌矿山开采区尾矿坝土壤中植物中毒和胁迫机制，使用同步辐射微束X射线荧光技术（μ-SRXRF）研究了K ，Ca ，Mn ，Fe ，Cu ，Zn ，Pb等元素在云南某铅锌矿区尾矿坝土壤中生长的拟南芥幼苗中的分布特征。发现Pb易富集于植物根部，也容易富集在植物顶端叶芽部位，这是很多研究没有发现的。整株幼苗中Pb都与M n形成明显的竞争分布特征。导致植株中毒凋亡的原因可能是Pb造成的拟南芥顶端幼芽的氧化压力，以及Pb分布对M n等植物必需元素的吸收和分布的抑制。为研究Pb在土壤中的形态和植物可利用性，针对拟南芥及其根际土壤中开展了Pb L3边X射线吸收近边精细结构谱（XANES）研究，发现尾矿坝土壤种植的拟南芥根际土壤Pb主要以PbO（64.2％），Pb（OH）2（28.8％）， Pb3 O4（6.3％）形式存在，而非Pb矿物矿石或有机 Pb形式存在，本尾矿坝土壤中 Pb的植物可利用水平不高。进一步开展土壤中Pb进入植物的过程以及该过程中Pb的形态发生的变化，尤其是溶解性有机质在其中的角色，是开展重金属胁迫下植物中毒和解毒机制研究的重要前提。
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