Eriksson Johan, Green Nicholas, Marsh Göran, Bergman Ake
Department of Environmental Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden.
Environ Sci Technol. 2004 Jun 1;38(11):3119-25. doi: 10.1021/es049830t.
Among all brominated flame retardants in use, the polybrominated diphenyl ethers (PBDEs) have been identified as being of particular environmental concern due to their global distribution and bioaccumulating properties, as observed in humans and wildlife worldwide. Still there is a need for more data on the basic characteristics of PBDEs to better understand and describe their environmental fate. Hence, the aim of this study was to investigate the photochemical degradation of PBDEs with different degrees of bromination. The photochemical degradation of 15 individual PBDEs substituted with 4-10 bromine atoms was studied in methanol/water (8:2) by UV light in the sunlight region. Nine of these were also studied in pure methanol, and four of the nine PBDEs were studied in tetrahydrofuran. The photochemical reaction rate decreased with decreasing number of bromine substituents in the molecule but also in some cases influenced by the PBDE substitution pattern. The reaction rate was dependent on the solvent in such a way that the reaction rate in a methanol/water solution was consistently around 1.7 times lower than in pure methanol and 2-3 times lower than in THF. The UV degradation half-life of decaBDE (T1/2 = 0.5 h) was more than 500 times shorter than the environmentally abundant congener 2,2',4,4'-tetraBDE (T1/2 = 12 d) in methanol/water. The quantum yields in the methanol/water solution ranged from 0.1 to 0.3. The photochemical reaction of decaBDE is a consecutive debromination from ten- down to six-bromine-substituted PBDEs. Products with less than six bromines were tentatively identified as brominated dibenzofurans and traces of what was indicated as methoxylated brominated dibenzofurans.
在所有正在使用的溴化阻燃剂中，多溴二苯醚（PBDEs）因其在全球范围内的分布以及生物累积特性而被视为具有特殊环境影响的物质，这在全球范围内的人类和野生动物中都有体现。然而，仍需要更多关于多溴二苯醚基本特性的数据，以便更好地理解和描述它们在环境中的归宿。因此，本研究的目的是调查不同溴化程度的多溴二苯醚的光化学降解情况。在甲醇/水（8:2）体系中，利用太阳光区域的紫外线研究了15种分别带有4至10个溴原子取代基的多溴二苯醚单体的光化学降解。其中9种还在纯甲醇中进行了研究，9种中的4种在四氢呋喃中进行了研究。光化学反应速率随着分子中溴取代基数量的减少而降低，但在某些情况下也受多溴二苯醚取代模式的影响。反应速率取决于溶剂，甲醇/水溶液中的反应速率始终比纯甲醇中低约1.7倍，比四氢呋喃中低2至3倍。在甲醇/水中，十溴二苯醚的紫外线降解半衰期（T1/2 = 0.5小时）比环境中含量丰富的同系物2,2',4,4'-四溴二苯醚（T1/2 = 12天）短500多倍。甲醇/水溶液中的量子产率范围为0.1至0.3。十溴二苯醚的光化学反应是一个连续脱溴过程，从十个溴取代基降至六个溴取代基的多溴二苯醚。初步鉴定出溴原子数少于六个的产物为溴代二苯并呋喃以及痕量的甲氧基化溴代二苯并呋喃。
