Using disposable solid-phase microextraction (SPME) to determine the freely dissolved concentration of polybrominated...

Polybrominated diphenyl ethers (PBDEs) are brominated flame retardants (BFRs). The ubiquity and persistence of PBDEs in sediment have raised concerns over their environmental fate and ecological risks. Due to strong affinity for sediment organic matter, environmental fate and bioavailability of PBDEs closely depend on their phase distribution. In this study, disposable polydimethylsiloxane (PDMS) fiber was used to derive the freely dissolved concentration (C(free)) of PBDEs in sediment porewater as a measurement of bioavailability. The PDMS-to-water partition coefficient (log K(PDMS)) was 5.46-5.83 for BDE 47, 99, and 153. In sediments, PBDEs were predominantly sorbed to the sediment phase, with C(free) accounting for <0.012% of the total chemical mass. The C(free) of PBDEs decreased as their bromination or sediment organic carbon content increased. The strong association with dissolved organic matter (DOM) implies a potential for facilitated offsite transport and dispersion in the environment that depends closely on the stability of sediment aggregates.