胶州湾滨海湿地中的Li、Rb、Cs、Sr、Ba及碱蓬（Suaeda salsa）对其的“重力分馏”

摘要

In this paper,we report the distributions of alkali metals（Li,Rb,and Cs） and alkaline-earth metals（Sr and Ba） in saline soils and Suaeda salsa and the accumulation characteristics of these elements in S.salsa from the northeastern coastal wetland of the Jiaozhou Bay.The variations in both the alkali metal and alkaline-earth metal concentrations were relatively small.Among these metals,the concentrations of Li,Sr,and Ba were higher than the background values of China＇s soils,whereas the concentrations of Rb and Cs,especially that of Cs,were lower than the background values.Li/Cs ratio was close to Ba/Sr ratio.Moreover,there were significant positive correlations between Li and Cs and between Sr and Ba,suggesting that the soils in this area mainly came from weathering of minerals that had high potassium content（e.g.,potash feldspar）,which was coincident with the parent materials（i.e.,granite） widely distributed in the Qingdao area.Although the accumulation of alkaline-earth metals by S.salsa was more than that of alkali metals,all enrichment factors（EFs） were less than one,suggesting that S.salsa posed no accumulative ability for either alkali metals or alkaline-earth metals.The order of EFs was：Sr Li Rb Cs Ba,and the EFs in aboveground tissues of S.salsa were less than one,suggesting that S.salsa had no general characteristics of accumulation plants.Transfer efficiencies of Li,Rb,and Sr by S.salsa were large and most of them were transferred into the aboveground tissues,and Li accumulation was high in leaves.The accumulation of Cs and Ba by S.salsa was low and most of the accumulation was limited in roots.A new conclusion is that S.salsa may cause ＂gravity fractionation＂ of Li,Rb,Cs,Sr,and Ba,e.g.the larger the atomic number,the less of the migrated amount to the aboveground tissues in S.salsa.%通过对胶州湾东北部滨海湿地5个站点盐渍土壤和其上生长的碱蓬中的微量碱金属、碱土金属Li、Rb、Cs、Sr、Ba的系统研究,发现盐渍土壤中Li、Sr和Ba的含量高于我国土壤背景值,Rb、Cs的含量特别是Cs的含量低于我国土壤的背景含量,盐渍土壤中Li/Cs比值和Ba/Sr比值较为接近,并且Li和Cs、Sr和Ba之间具有显著的正相关关系,表明这一区域的盐渍土壤有相似的成土母质。碱蓬对碱土金属的积累量明显高于碱金属,但对它们的富集系数都小于1,碱蓬生物富集系数Sr〉Li〉Rb〉Cs〉Ba,碱蓬对这五种元素从盐渍土壤中迁出的能力随着它们原子序数的增加明显降低,即越重的元素越不易被迁离地面移出盐渍土壤,相反,越轻的元素越易被迁离地面移出盐渍土壤,碱蓬可造成盐渍土壤Li、Rb、Sr、Cs、Ba明显的＂重力分馏＂。