Photo-induced degradation and toxicity change of decabromobiphenyl ethers (BDE-209) in water: Effects of dissolved organic matter and halide ions

• Published in: Journal of hazardous materials Vol. 416; p. 125842
• Main Authors: Cheng, Fangyuan, He, Jiale, Li, Chao, Lu, Ying, Zhang, Ya-nan, Qu, Jiao
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15-08-2021
• Subjects: Decabromobiphenyl ethers; Dissolved organic matter; Halide ions; Photodegradation; Toxicity effect; Photodegradation; Decabromobiphenyl ethers; Halide ions; Toxicity effect; Dissolved organic matter
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2021.125842

BDE-209 is a widely used brominated flame retardant that is ubiquitous in the aquatic environment, especially in marine water. However, photodegradation of BDE-209 in seawater is still not fully understood. In this work, the photodegradation kinetics of BDE-209 in water was studied and the effects of seawater dissolved organic matter (S-DOM) and halide ions (Cl−, Br−) were evaluated. S-DOM inhibited the degradation of BDE-209 through dynamic quenching and light shielding effect. However, with the coexistence of S-DOM, Cl− and Br−, the photodegradation of BDE-209 was significantly promoted. The promotional effect is attributed to the generation of excited triplet state S-DOM, singlet oxygen, and reactive halogen radicals. The results of density functional theory calculation showed that •Cl addition reaction on C-Br sites of BDE-209 is the main reaction pathway of BDE-209 with chlorine radical, which leads to the generation of mixed Cl/Br substituted intermediates. The acute toxicity and estrogenic effects of BDE-209 solution were enhanced during simulated sunlight irradiation. These results indicate that the environmental factors in seawater play important roles in the photodegradation of BDE-209, and contribute to the potential ecological risks of PBDEs in the marine environment.
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•S-DOM alone inhibited the photodegradation of BDE-209.•The coexistence of S-DOM and halide ions promoted the photodegradation of BDE-209.•Mixed Cl/Br intermediates can be generated in the •Cl addition reaction with BDE-209.•Acute toxicity and estrogenic effect of BDE-209 were enhanced during photodegradation.