HA1 Contaminated Harbour and River Sediment
256 Portland Ballroom
8:00 AM - 12:00 PM, Thursday
() Transport and Fate of Hazardous Substances in a Capped Sediment System.
Valsaraj, Kalliat1, Yuan, Qingzhong1, 1 Louisiana State University, Baton Rouge, LA, USA
ABSTRACT- Two kinds of capping materials (sand and Florida phosphate) were used to investigate the transport and fate of several PAHs and metals from two sediments (Anacostia river , Washington, D.C and University Lake, Baton Rouge, LA). Using diffusion chambers, flux data and concentration profiles of 3 PAHs and 18 metals have been measured. From the data, the effectiveness of both conventional and active caps were ascertained. The influence of sediment consolidation on contaminant diffusion through the cap and its effect on the mass transfer coefficients at the interface between water and sediment were ascertained using a gypsum-wafer method. A two-layer diffusion model was employed to fit the data for the PAHs, and satisfactory results were obtained. At the same time, oxygen diffusion in both cap and sediment were studied. Oxygen probes and an SOD chamber were used to measure the sediment oxygen demand. Redox potentials in the sediment and cap were determined with platinum electrodes and calomel reference electrodes. With the help of microelectrodes, oxygen profiles in the sediment were measured and simulated by a steady state diffusion/reaction model. Satisfactory match was observed between the oxygen profiles and the redox potential data at different depths in the contaminated sediment and cap material.
Key words: Capping, Sediment, Active, Remediation