M6 PM Fate and Transport of Pollutants from Dredging and Placement
Monday, 14 November 2005: 1:50 PM - 5:30 PM in 324-326

(ZAH-1118-072753) Quantifying the Fate of Organic Contaminants Released due to Dredging Operations.

Zahakos, H¹, ¹ Quantitative Environmental Analysis, LLC, Montvale, NJ, USA

ABSTRACT- The dispersal of contaminated sediments during dredging operations is a major concern. Material lost to the water column has the potential to adversely impact water quality and aquatic life over a much broader area than the immediate vicinity of the dredging operation. Hydrodynamic conditions and sediment properties determine the fate of resuspended sediments and particulate-bound contaminants. Contaminant desorption during resuspension results in greater dispersal and bioavailability of contaminants. Conventional fate models assume equilibrium partitioning between sorbed and aqueous phases. This is often adequate to assess long-term contaminant fate, for example as part of remedial investigations. During dredging resuspension and redeposition, however, short time scales dominate. This can invalidate the equilibrium assumption. A new mechanistic modeling framework has been developed. This model integrates laboratory studies on contaminant sorption/desorption dynamics with hydrodynamic and sediment transport processes that affect contaminant fate from dredge losses. The model accommodates multiple sediment classes and desorption rates. Simulations illustrate the importance of local hydrodynamic conditions and sediment properties on the fate and bioavailability of contaminants.

Key words: pcb, dredging, modeling, desorption