Using Polyethylene Passive Samplers To Study the Partitioning and Fluxes of Polybrominated Diphenyl Ethers in an Urban River

In the aquatic environment, the behavior of hydrophobic organic contaminants (HOCs), such as polybrominated diphenyl ethers (PBDEs), depends on the congeners' physicochemical properties, environmental conditions and the presence of competing natural sorbents, including particulate and dissolved organic carbon (DOC) and black carbon (BC). Although BC is known as an important sedimentary sorbent for HOCs, its affinity for PBDEs has been poorly constrained. To better understand the biogeochemical controls on PBDEs, 12 PBDE congeners were measured in air, water, sediment and porewater of the lower Passaic River. BDE-47 and BDE-99 dominated in all media. In sediments and water, the dual OC + BC approach better predicted PBDE partitioning compared to the simple OC isotherm. Field-derived K-BC values for PBDEs were inversely correlated with aqueous solubility [log KBC sediments(water) = -log C-w(sat) * 0.95 (1.2) + 0.36 (-0.69)]; they reflected near background to highly contaminated regions across the Passaic River. In the water column, PBDEs appeared at equilibrium partitioning between particles and colloids: OC + BC were responsible for the sorption of 65% of PBDEs, followed by colloids (30%); only 5% of PDBEs were truly dissolved. Calculated sediment-water diffusive fluxes greatly overwhelmed the atmospheric depositional flux to the river.