红树植物秋茄对PCBs污染沉积物的修复

通过盆栽试验,研究了红树植物秋茄(Kandelia candel)对污染沉积物中系列浓度的PCB47(2,2′,4,4′-tetrachlorobiphenyl)和PCB155( 2,2′,4,4′,6,6′, -hexachlorophenyl)的修复作用与累积机理.结果表明:(1)经过180d处理,栽种了秋茄的沉积物中PCB47的残留浓度为53.99～528.37μg·kg-1,PCB155的残留浓度为68.25～682.90μg·kg-1,分别比对照1(加二氯化汞)低10.40%～15.46% 和6.10%～11.94%;比对照2(无二氯化汞)低7.70%～12.85% 和5.28%～8.27%;(2)秋茄对沉积物中PCB47和PCB155均具有较强的吸收积累作用,并随沉积物中PCB47和PCB155含量的增加而增大,不同种类PCBs在秋茄体内不同部位的积累趋势相同,不论是PCB47还是PCB155的累积量均是根> 叶> 茎.秋茄叶片中多氯联苯来自根部传输和空气吸收两部分,较低浓度的处理中,主要来自空气吸收,较高浓度的处理中,主要来自根部传输;(3)秋茄根对PCBs的生物富集系数(BCFs) 随着沉积物中PCB47和PCB155含量的增加而减小.不同种类PCBs 以及植物不同部位间BCFs 差异较大, PCB47的生物富集系数大于PCB155, 秋茄不同部位对PCBs生物富集系数大小不同,无论是PCB47还是PCB155,生物富集系数均是根＞叶＞茎.总体看来,秋茄能积累与去除污染沉积物中的PCB47和PCB155,表明用红树植物秋茄修复PCBs污染沉积物是一种有效、可行的方法.

The phytoremediation of the sediments contaminated with PCBs by mangrove species Kandelia candel

In this study, mangrove (Kandelia candel) seedlings were planted in sediments contaminated with a series of concentrations of PCB47(2,2′,4,4′-tetrachlorobiphenyl)and PCB155( 2,2′,4,4′,6,6′, - hexachlorophenyl). The ability and mechanisms of Kandelia candel to remediate PCB47 and PCB155 were studied. At the end of a 180-day experiment, the residual concentrations of PCB47 and PCB155 were lower in the sediments planted with Kandelia candel than in non-planted sediments. The residual concentrations of PCB47 and PCB155 in planted sediments were 53.99-528.37μg · kg~(-1) and 68.25-682.90μg · kg~(-1), respectively,which were 10.40%-15.46% and 6.10%-11.94% lower than control 1 (with addition of HgCl2), and 7.70%-12.85% and 5.28%-8.27% lower than control 2 (without HgCl2). Kandelia candel could take up PCBs from the sediments, and generally took up more PCBs when PCB concentrations were higher. The concentrations of PCB47 and PCB155 in Kandelia candel were highest in the root, followed by the leaves, and lowest in the shoot. The accumulation of PCBs in Kandelia candel leaves was from two pathways. Root uptake and transport to the leaves was the main uptake pathway in the sediments with higher level concentrations of PCB47 and PCB155. Volatilization from soil and uptake by aerial plant part was the main uptake pathway in the sediments with lower level concentration of PCB47 and PCB155; Root bioconcentration factors (BCFs) of Kandelia candel for PCB47 and PCB155 tended to decrease with increasing concentrations of the contaminants in sediment, and the BCFs for PCB47 were larger than those for PCB155. The BCFs for PCB47 and PCB155 in Kandelia candel was highest in the root, followed by the leaves, and lowest in the shoot. Results from this experiment indicated that removal of PCBs from contaminated sediments by mangrove species Kandelia candel may be a feasible approach to sediment remediation.