Sediment-water Flux of Hydrophobic Organic Chemicals Due to Molecular Diffusion and Bioturbation

Résumé du livre

In order to investigate the flux of HOCs due to molecular diffusion as modified by sorption, experiments have been conducted in two different sediments with HOCs which have a range of partition coefficients, Kp, from 5 x 104 to 10 L/kg. Lengths of the experiments ranged from 32 d to 256 d. For large Kp's, the results demonstrate that (1) significant changes in HOC concentrations are limited to a few millimeters near the sediment-water interface, (2) measured values of the HOC concentration are generally much less than their equilibrium value, and (3) the flux depends on Kp and is much greater than that for a non-sorbing chemical. As Kp decreases, the results reduce to those expected for pure molecular diffusion without sorption. A theoretical model has been developed which is uniformly valid for all HOCs tested. Good agreement between the numerical calculations and experimental results is obtained.