氯代苯在叶菜和根菜类蔬菜中的分布与富集

Distribution and accumulation of chlorobenzenes in vegetables

分析了邻二氯苯(o-DCB)、间二氯苯(m-DCB)、对二氯苯(p-DCB)和1,2,4-三氯苯(1,2,4-TCB)4种典型低分子量氯代苯(CBs)在几种典型叶菜类和根菜类蔬菜及土壤中的含量,研究其在土壤-蔬菜间的分配关系,并运用分配限制模型进行机理探讨.结果表明,低分子量的CBs主要以m-DCB和1,2,4-TCB形式在叶菜类和根菜类蔬菜中累积;CBs在蔬菜中的富集表现为菠菜、白菜和芹菜中根>叶>茎,而白萝卜和胡萝卜为叶>茎>根,符合分配限制模型,表明根部吸收是低分子量CBs进入植物的主要途径,其生物富集主要与蔬菜脂肪含量、污染物Kow有关.

Five seasonal vegetables and the soils in three different districts were investigated with respect to levels of chlorobenzenes(CBs), including 1,2-DCB(o-DCB), 1,3-DCB(m-DCB), 1,4-DCB(p-DCB), 1,2,4-TCB. The partition relationship in different parts of vegetables was analyzed and the partition-limited model was used to explain the bioaccumulation of CBs by vegetables. As shown by our result, m-DCB and 1,2,4-TCB,which have relatively low molecular weight, were the predominant CBs in vegetables. The accumulation of CBs in spinach (Spinacia oleracea), Chinese cabbage (Brassica rapavar. pekinensis), and celery (Apium graveolensvar. dulce), expressed as concentration of CBs in discending order was root > leaf > stem. While in radish (Raphanus sativus) and carrot (Daucus carota subsp. sativus) it was leaf > stem > root. This was suitable for the partition-limited model, and this implied that root was the main pathway thorugh which CBs enter vegetable plants and the accumulation was well related with Kow, the lipid content of the vegetable.