某铀尾矿库土壤核素污染与优势植物累积特征

Soil Radionuclide Contamination and Radionuclide Accumulation Characteristics of Competitive Plants in a Uranium Tailings Repository in South China

采用野外采样和电感耦合等离子体质谱仪分析法,测定某铀尾矿库内自然生长的14种优势植物及其根系土壤中核素的含量,并针对植物对核素的耐受性和富集性能进行分析.结果表明:双穗雀稗(Paspalum distichumL.)、圆果雀稗(Paspalumorbiculare Forst.)、水莎草〔Juncellus serotinus(Rottb.)C.B.Clarke〕、水蜈蚣(Kyllinga brevifolia Rottb)和碎米莎草(Cyperus iriaL.)的地上部分及金毛狗〔Cibotium barometz(Linn.)J.Sm.〕的地下部分对铀(U)和钍(Th)均有不同程度的累积.莎草科的碎米莎草的地上部分对U的富集系数高达6.04,其余植物的富集系数均小于1;一部分植物样对U的转移系数小于1.莎草科的水蜈蚣对Th的转移系数为2.56,其他植物的转移系数均小于0.50.莎草科植物对U的吸收富集性能明显优于其他科植物,碎米莎草对U则表现出超耐受性和超富集性.

Site sampling and inductively coupled plasma mass spectrometry analysis were used to determine the contents of U and Th in the rhizosphere soil and plant of 14 kinds of competitive plants which grow naturally in a uranium tailings repository.The resistances to the radionuclide and radionuclide accumulation capabilities of these plants were analyzed.The results showed that Paspalum distichum L.,Paspalum orbiculare Forst.,Juncellus serotinus（Rottb.） C.B.Clarke,Kyllinga brevifolia Rottb and Cyperus iria L.have some U and Th in their shoots,and Cibotium barometz（Linn.） J.Sm.has some U and Th in its roots.The bioconcentration factor of uranium in the shoot of Cyperus iria L.amounts to 6.04,while the bioconcentration factors of the other plant species are less than 1.Some plant species have transfer factors for U smaller than 1.Kyllinga brevifolia Rottb has a transfer factor of 2.56 for Th,while the other plants have transfer factors less than 0.50.The uptake of Cyperus iria L.to uranium is superior to the other families of plants;it is a potential hyperaccumulator for uranium.