MASS-TRANSFER OF TCDD F FROM SUSPENDED SEDIMENT PARTICLES/

Experimentally determined mass transfer rates for the non-polar hydrop hobic compounds known as tetra-chlorinated dibenzo-dioxin/furans (TCDD /F) were obtained by exposing contaminated sediment materials of two k nown size classes to a high grade distilled water in a completely mixe d state for periods of up to 90 days. Water samples were removed at fo ur time intervals, filtered through 1.2 mum and 0.7 mum glass fiber fi lters and subsequently analyzed for aqueous TCDD/F content using high resolution GC-MS methods. The results suggest that the mass transfer r ates of highly hydrophobic compounds (log K(ow) > 6) are affected prim arily by the release of dissolved and colloidal size organic carbon ma terials and to a lesser degree by exposure time. The experimental data also suggest that the unquestioned use of equilibrium partitioning (E P) theory assumptions in water quality models may not be justified. An empirical model is presented that can predict water column TCDD/F con centrations due to chemical release from suspended solids.