多氯联苯在紫花苜蓿体内的积累、分布及形态

Accumulation,Distribution and Chemical Speciation of PCBs in Different Parts of Alfalfa

以紫花苜蓿为材料,研究了多氯联苯(PCBs)在植物根、根瘤、地上部中的积累、分布及存在形态。结果表明,PCBs在紫花苜蓿根、根瘤和茎叶部均有不同程度的积累,其含量为根瘤>根>茎叶,而积累量则表现为根>茎叶>根瘤,其差异均达极显著水平(p<0.01),根系表现为主要富集部位。化学连续提取法结果表明,紫花苜蓿根中PCBs可分为根表弱吸着态、根表强吸着态和根内吸收态等3种形态,根系中富集的PCBs约78%为根表强吸着态,被植物组织紧密吸附;仅2%左右可以进入根系内部被根吸收(即根内吸收态),且全部为2氯代的PCB8,低氯代PCBs组分更易被植物吸收转运。

The accumulation, distribution and chemical speciation of PCBs by different parts of alfalfa from soil were investigated. The results indicated that the total PCBs concentrations in the different parts of alfalfa can be arranged as root nodules〉roots〉shoots, however, the amounts of total PCBs accumulated in the different parts of alfalfa were in the order of roots〉shoots〉root nodules, and the difference reached significant level, alfalfa roots were the main enrichment parts of PCBs in plant. A chemical sequential extraction procedure was developed to measure the adsorbed, strongly adsorbed and interior absorbed fractions of PCBs in alfalfa roots. The results showed that about 78% of the total PCBs detected was strongly adsorbed in the root tissues, only around 2% of the PCBs detected were absorbed by interior alfalfa roots and which all were dichlorobiphenyl （PCB8）, low chlorinated PCB congeners were easily absorbed by plant tissues.