Studies of brominated flame retardants have raised awareness of their potential environmental impact as toxic compounds.  Because these compounds are now globally distributed, including in the Polar Regions, it is important to assess their potential fate in the environment. It has been shown that active photochemistry occurs in sunlit snow and ice, but there is little information regarding potential photochemical degradation of brominated flame retardants in snow and ice.  We have conducted field-based experiments in Barrow, Alaska to investigate the potential photochemical degradation of TBBPA in snow and ice under environmentally-relevant conditions.  Field-based results show that TBBPA is efficiently degraded under direct photolysis conditions in frozen aqueous samples under natural Barrow sunlight.  In aqueous solution the light absorption properties of TBBPA are pH dependent.  Therefore, the photodegradation of TBBPA in snow and ice will be highly pH dependent.  Reactions that are pH dependent may be affected by the nature of the liquid-like layers in snow/ice as well as the presence of other solutes that may indirectly affect the local pH experienced by TBBPA in snow and ice samples.  In order to establish how the effective pH of liquid-like regions in ice might impact the degradation of TBBPA, various salts were added to aqueous solutions of TBBPA.  Upon freezing, these different salts will induce pH differences in the liquid-like regions of the sample due to a phenomenon known as the freezing potential.  Observed reactivity differences upon addition of these salts will be discussed.  Additionally, the presence of dissolved organic matter (DOM), an effective environmentally-relevant photosensitizer, has the potential to cause indirect photochemical degradation of TBBPA and this degradation pathway was also evaluated under laboratory conditions.

Photochemical degradation of a brominated flame retardant (tetrabromobisphenol A) in ice under field and laboratory conditions

248th National Meeting (2014)

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