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Uptake Pathway, Translocation, and Isomerization of Hexabromocyclododecane Diastereoisomers by Wheat
发布时间：2018/3/1 点击次数：583
To study the uptake pathways of 3 main hexabromocyclododecane diastereoisomers (α-, β-, and γ- HBCDs) in wheat, four closed chambers were designed to expose wheat to HBCDs via air and/or soil for 4 weeks. The results showed that HBCDs could be absorbed by wheat both via root from soil and via leaf from air. The Rt values (ratio of HBCDs from root-to-leaf translocation to the total accumulation in leaves) ranging from 14.4 to 29.8% suggested that acropetal translocation within wheat was limited. A negative linear relationship was found between log Rt and log Kow of the HBCD diastereoisomers (p < 0.05). The bioconcentration factors (BCFs, (μg/g wheat tissues)/ (μg/g soil)) were in the order α- > β- > γ-HBCD in wheat roots and stems, being negatively related to their Kow values. No such correlation was found in leaves, where the HBCDs came mainly from air distribution. The results of enantiomeric fractions indicated that the (?)-enantiomer of α- and γ-HBCDs and the (+)-β-enantiomer were selectively accumulated. Furthermore, β- and γ-HBCDs were transformed to α-HBCD in the wheat, with 0.309?4.80% and 0.920?8.40% bioisomerization efficiencies at the end of the experiment, respectively, being the highest in leaves. Additionally, no isomerization product from α-HBCD was found.（研究小麦中3种对映体六溴环十二烷二体异构物的吸收途径,结果显示HBCDs能通过根从土壤中和通过叶子从空气中吸收。Rt值从14.4到29.8%说明小麦的顶叶易位是有限的。在HBCDs的非对映体发现了logRt和logKow 的负线性关系。在叶子中没有发现这种相关性,hbcd主要来自于空气传播。对映体的比例说明对映体α-&γ-HBCDs和β-HBCDs是有选择性积累的,而且小麦中β-and γ-HBCDs可以转换成α-HBCDs）
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