四溴双酚A在近岸海水中的光降解动力学研究

Photodegradation kinetics of tetrabromobisphenol A in coastal water

四溴双酚A(TBBPA)是水环境中被经常检出的一种新型污染物,因其具有潜在的生态与健康风险而备受关注.本研究考察了模拟日光照射下,TBBPA在纯水、淡水和海水中的光降解行为.结果表明,TBBPA在海水中的光降解慢于其在纯水和淡水中的光降解,海水中溶解性物质对TBBPA的光降解总体表现为抑制作用.选用提取自黄海水中的溶解性有机质(H-DOM)和Suwannee河天然有机质(SRNOM),研究了DOM对TBBPA光降解的影响,发现DOM主要通过竞争光吸收抑制TBBPA的光降解,但H-DOM的抑制作用弱于SRNOM.还考察了Cl^-和Br^-对TBBPA光降解的影响,发现Cl^-通过淬灭单线态氧和激发三线态TBBPA而抑制TBBPA的光降解;Cl^-的离子强度效应及Br^-对TBBPA的光降解没有显著影响.基于测定的数据,预测了TBBPA在黄河三角洲区域的淡水、河口水和海水中的光降解速率常数.结果表明,TBBPA在表层海水中的光降解速率最慢,但当水深超过0.05 m时,其在海水中的光降解速率会超过在淡水和河口水中的光降解速率.本研究对评价TBBPA在近岸海水中的归趋具有重要意义.

Tetrabromobisphenol A（ TBBPA） is an emerging pollutant that has been frequently detected in the aquatic environment. TBBPA has attracted extensive attention due to its potential ecological and health risks. In this study,we investigated photodegradation kinetics of TBBPA in pure water,freshwater and seawater under the irradiation of simulated sunlight. The results show the photodegradation rate of TBBPA in seawater was slower than in pure water and freshwater. Water constituents in seawater inhibited the photodegradation. Dissolved organic matter extracted from the Yellow Sea seawater（ H-DOM） and the Suwannee River natural organic matter（ SRNOM） were selected to investigate the effects of DOM on the photodegradation of TBBPA. It was found that DOM inhibited the photodegradation via competitive light absorption,and the inhibition of H-DOM wasweaker than that of SRNOM. The photodegradation was inhibited by Cl- via quenching of singlet oxygen and triplet excited TBBPA. Br- and the ionic strength had no obvious effects on the photodegradation. Based on the determined parameters,photodegradation rate constants of TBBPA in the Yellow River Delta freshwater,estuarine water and seawater were estimated. The rate in the surface seawater was the slowest; Nevertheless,the rate constants in seawater became higher than those in the freshwater and estuarine water at a depth of 0. 05 m. The results are important in elucidating the fate of TBBPA in coastal waters.