Uptake Pathway, Translocation, and Isomerization of Hexabromocyclododecane Diastereoisomers by Wheat

發(fā)布時間：2018/3/1 點擊次數(shù)：432

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.（研究小麥中3種對映體六溴環(huán)十二烷二體異構(gòu)物的吸收途徑,結(jié)果顯示HBCDs能通過根從土壤中和通過葉子從空氣中吸收。Rt值從14.4到29.8%說明小麥的頂葉易位是有限的。在HBCDs的非對映體發(fā)現(xiàn)了logRt和logKow 的負(fù)線性關(guān)系。在葉子中沒有發(fā)現(xiàn)這種相關(guān)性,hbcd主要來自于空氣傳播。對映體的比例說明對映體α-&γ-HBCDs和β-HBCDs是有選擇性積累的,而且小麥中β-and γ-HBCDs可以轉(zhuǎn)換成α-HBCDs）

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Uptake Pathway, Translocation, and Isomerization of Hexabromocyclododecane Diastereoisomers by Wheat