Efficiency of Capping Contaminated Bed Sediments in Situ. 1. Laboratory-Scale Experiments on Diffusion–Adsorption in the Capping Layer

A laboratory study was performed on the transport of the hydrophobic organic compound, 2, 4, 6-trichlorophenol (TCP), through a layer of clean sediment placed over contaminated sediment inoculated with TCP. A capped simulator cell (CSC) was designed for the study and four capping materials of 0.7-cm depth with different organic carbon contents and textures were used. A conceptual model of TCP fate combining molecular diffusion in interstitial porewater and partitioning onto fresh sediment was developed to assess the data. TCP breakthrough times and effective diffusivities for the various capping materials gave good comparisons with theoretical predictions.