Contaminated sediments

Wilbert Lick, Ph.D.
University of California, Santa Barbara

Wednesday, November 20, 2002
3:00 p.m. Pacific Forum

Contaminated sediments are a major problem in rivers, lakes, estuaries, and near-shore areas of the oceans. If the problem 
is severe enough, these sediments must be remediated. In eval-uating potential remedial actions, the most significant problem is usually the quantitative prediction of the fluxes of contam-inants between the sediments and the overlying water under present and future conditions. This involves the consideration 
of big events, such as large storms and floods, and long-term predictions—typically 10, 20, and 50 years. The flux of contam-inants between sediments and overlying water is due to sedi-ment resuspension and deposition, bioturbation, molecular diffusion, pore-water convection, and gas transport. When chemicals have large partition coefficients, time- dependent, non-equilibrium sorption continuously modifies the concentra-tions and fluxes of these chemicals in the sediments. The various flux processes as modified by time-dependent sorption will be described. Experimental results and models of these processes will be used to estimate and compare the mag-nitudes of these fluxes for different realistic conditions.

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