Uptake Pathway, Translocation, and Isomerization of Hexabromocyclododecane Diastereoisomers by Wheat in Closed Chambers

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• 作者：Hongkai Zhu ; Hongwen Sun ; Yanwei Zhang ; Jiayao Xu ; Bing Li ; Qixing Zhou
• 刊名：Environmental Science & Technology
• 出版年：2016
• 出版时间：March 1, 2016
• 年：2016
• 卷：50
• 期：5
• 页码：2652-2659
• 全文大小：461K
• ISSN：1520-5851

文摘

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 R_t 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 R_t and log K_ow 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 K_ow 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.