多氯联苯在水稻田中的迁移行为

Transport of PCBs in contaminated paddy fields

对典型污染地区水稻田土壤及作物中多氯联苯的含量和分布特征进行了研究 .结果表明 ,土壤中以 4- 6氯取代的PCBs同类物 (congeners)为主 ,三者占PCBs总量的 85 %以上 ;多氯联苯在土壤中的横向和纵向迁移行为很弱 ,同类物之间表现出不同的迁移特性 ;水稻对多氯联苯没有明显的生物富集作用 ;水稻不同组织中多氯联苯的含量相差很大 ,其中浓度分布顺序为稻叶 >稻壳 >稻杆 >糙米 ;

PCBs transport in paddy field was investigated. The soil and rice samples were analyzed for PCBs contamination. Tetra to hexa chlorinated polychlorinated biphenyl were dominant in soil samples from paddy field. These three homolog groups accounted for >85% of PCBs in the soil samples. The distribution of PCBs in different depths of soil showed that high chlorinated PCB congeners barely migrate to deeper layer through pore water. It was showed that rice grown in the field appeared somewhat contamination by PCBs, but it was not likely subjected to significant bioconcentration of PCBs from contaminated soil directly. The PCB concentrations in the different tissues were different from each other. The maximum concentration was observed in leaves. The volatilization of PCBs from soil and subsequent adsorption onto the plant was suggested to be the predominant mechanism of PCBs contamination.