Photochemical transformation of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) in surface coastal waters: effects of chloride and ferric ions.

The effects of several aquatic environmental factors on the photochemical transformation of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) have been investigated. Ferric ion (Fe(III)) has been found to promote the phototransformation of BDE-47, and this process is further enhanced with the added chloride ion (Cl(-)), while it is suppressed with increasing pH. Electron spin resonance results show that the formation of hydroxyl radical, and the added Cl(-) could influence the generation of hydroxyl radical in Fe(III) solution. Hence, Cl(-) enhances the phototransformation of BDE-47 most probably because of the reaction with Fe(III) species under irradiation, yielding hydroxyl and chloride radicals. These radicals can not only decompose PBDEs, but also lead to their photodebromination and photochlorination. These results indicate that the aquatic environmental factors and Cl(-) in particular played an important role in the photochemical transformation process of PBDEs, providing insight into the likely fate of PBDEs in the marine environment.