十溴二苯醚及其降解产物对浮游生物的毒性

十溴二苯醚(BDE-209)是我国环境中主要的多溴二苯醚(PBDEs)同系物.为研究BDE-209及其降解产物对水环境的影响,以初级消费者浮游动物大型蚤(Daphnia magna)和初级生产者浮游植物水华微囊藻(Microcystis flos-aquae)为染毒对象,研究BDE-209及其降解不同阶段产物对浮游生物的毒性.结果表明,大型蚤方面,繁殖毒性大于生长毒性,48 h半数致死浓度(48h-LC50)大小为:还原降解中间产物(0.80 mg·L~(-1),高毒)BDE-209(8.74 mg·L~(-1),中毒)还原降解终产物(15.27 mg·L~(-1),低毒),还原-氧化降解终产物的死亡率与溶剂空白一致,表明其基本无毒.水华微囊藻方面,染毒物质的毒性大小顺序与大型蚤一致,1 mg·L~(-1)的BDE-209、还原中间产物、还原终产物及还原-氧化终产物对水华微囊藻的抑制率分别为15.7%、93.7%、6.6%和1.3%.BDE-209降解过程中易生成毒性较大的中间产物,彻底还原脱溴可降低其毒性,后续辅以氧化降解,可消除其环境毒性.

Toxicity of decabromodiphenyl ether and its degradation products to plankton

Decabromodiphenyl ether(BDE-209) is the primary congener of polybrominated diphenyl ethers(PBDEs) in the environment in China. In order to investigate the effects of BDE-209 and its degradation products on the aquatic environment, the zooplankton Daphnia magna(a primary consumer), and the phytoplankton Microcystis flos-aquae(a primary producer) were used to study the toxicities of BDE-209 and its degradation products of different stages. In Daphnia magna, the propagation toxicities were higher than that of growth. 48h-LC₅₀ of pollutants followed the order of intermediate reductive products(0.80 mg·L^-1, high toxicity) > BDE-209(8.74 mg·L^-1, moderate toxicity) > reductive final products(15.27 mg·L^-1, low toxicity). The motality of the final reductive-oxidative products was comparable with that caused by the solvent, indicating that it was largely nontoxic. In Microcystis flos-aquae, the toxicity of pollutants followed the same order as in Daphnia magna, under the condition of 1 mg·L^-1 of BDE-209, intermediate products, the final reductive products, or the final reductive-oxidative products, the inhibition rate for Microcystis flos-aquae were 15.7%, 93.7%, 6.6% and 1.3%, respectively. During the BDE-209 degradation process, greater toxic intermediate products were generated. However, their environmental toxicity would be reduced if the reductive debromination process could be completely conducted, and moreover, their environmental toxicity would even be eliminated if the reductive process was followed up by subsequent oxidative degradation process.