六溴環(huán)十二烷（HBCD）是一類用于電子、電器產(chǎn)品和建筑材料的重要溴系阻燃劑,，其使用量在所有溴系阻燃劑中處于第三位。HBCD已在環(huán)境介質(zhì)和生物樣品中廣泛檢出,。雖然其在工業(yè)用HBCD產(chǎn)品中以γ-HBCD為主,，但已有研究發(fā)現(xiàn),，在大部分生物樣品中α-HBCD是其主要組分，同時,，也有一些底棲水生生物及人體組織樣品中的HBCD以g-HBCD異構(gòu)體為主,。然而,，對造成這種組成差異的原因，目前尚不清楚,。
中科院所廣州地球化學(xué)研究所有機(jī)地球化學(xué)國家重點實驗室麥碧嫻研究組對采自廣東清遠(yuǎn)電子垃圾區(qū)的各種鳥類及其食物和相關(guān)環(huán)境樣品中的HBCD進(jìn)行了系統(tǒng)分析，發(fā)現(xiàn)HBCD在鳥體內(nèi)的異構(gòu)體組成與其棲息環(huán)境和食源存在較大的關(guān)聯(lián)性,。在水生鳥類池鷺體內(nèi)α-HBCD是主要甚至唯一被檢出組分；在陸生鳥內(nèi)中則發(fā)現(xiàn)γ-HBCD是主要組分,；而在一些濕地水鳥體內(nèi),，則沒有統(tǒng)一的選擇性富集α-或者γ-HBCD的現(xiàn)象,。結(jié)合穩(wěn)定碳同位素分析,，并與鳥類相應(yīng)食物和環(huán)境樣品的比對,，該研究組發(fā)現(xiàn)這種生物體內(nèi)選擇性富集某一HBCD立體異構(gòu)體的現(xiàn)象,，既受生物體內(nèi)代謝作用影響,，也受其食源影響,。
同時,，該研究還發(fā)現(xiàn)捕食者與被捕食者之間具有相似的手性組成，這表明生物體內(nèi)發(fā)現(xiàn)的HBCD手性選擇性富集現(xiàn)象,，并不必然是生物體內(nèi)發(fā)生手性選擇性代謝的結(jié)果，從食物中繼承也是一個重要原因,。
這一研究成果對解釋生物體內(nèi)HBCD的選擇性富集現(xiàn)象,，提供了新的視角,，也為正確認(rèn)識HBCD的生物富集與轉(zhuǎn)化提供了科學(xué)依據(jù),。（生物谷Bioon.com）
生物谷推薦英文摘要：
Environ. Sci. Technol. DOI: 10.1021/es1032597
Tetrabromobisphenol-A and Hexabromocyclododecane in Birds from an E-Waste Region in South China: Influence of Diet on Diastereoisomer- and Enantiomer-specific Distribution and Trophodynamics
Ming-Jing He, Xiao-Jun Luo, Le-Huan Yu, Juan Liu, Xiu-Lan Zhang, She-Jun Chen, and Bi-Xian Mai
Tetrabromobisphenol-A (TBBPA) and three diastereomers of hexabromocyclododecane (HBCD) were examined in the muscles of six bird species and their diet collected from an e-waste recycling region (Qingyuan) in South China. Stable isotope ratios (δ15N and δ13C) were analyzed to measure the diet source and trophic levels (TLs) of the birds. The median TBBPA and HBCD concentrations in the birds ranged from 28 to 173 and not detectable to 1995 ng/g lipid weight, respectively. The diastereoisomeric pattern shows the predominance of α-HBCD in birds feeding in an aquatic environment and that of γ-HBCD in birds feeding in a terrestrial environment, whereas no clear preference for α isomer or γ isomer was found in birds that inhabited freshwater wetland. A significant positive correlation between δ13C and percentage of α-HBCD was observed, indicating the importance of diet exposure pathways in the determination of HBCD diastereoisomer pattern. The enantiomer fractions (EFs) for α-HBCD differed substantially between aquatic and terrestrial bird species with a significant enrichment of (+) α-HBCD enantiomer for aquatic birds and a preferential enrichment of (?) α-HBCD enantiomer for terrestrial birds. The similarity in diastereoisomer profiles of HBCD and the EFs of α-HBCD between prey (fish) and predator (Chinese pond heron) also suggested that dietary exposure is an important contributor for the observed diastereoisomer- and enantiomer-specific distribution of HBCD in birds. Trophic magnification was observed for α-HBCD and TBBPA as concentrations increased with the TLs of the birds defined by δ15N, but only α-HBCD showed a strong positive relationship (p = 0.001). The biomagnification factors for α- and γ-HBCD and TBBPA were calculated based on individual predator/prey feeding relationships for two species.
