Principal Investigator Philip Gschwend
We are working to develop means to estimate the fluxes of organic pollutants (e.g., PAHs and PCBs) from harbor sediments. For highly sorptive compounds, we hypothesize that processes in the water column (diffusion across a bottom boundary layer of water, flushing of the overlying mixed water column) control the overall transfer in quiescent harbors, while episodic resuspension events control releases in more exposed harbors. We are assessing the accuracy of this view by: (1) estimating fluxes from site information (e.g., chemical concentrations, solid-water partition coefficients, boundary layer thickness', water column flushing rates, frequencies and intensities of resuspension), and (2) testing the estimates of transport rates by performing mass balance calculations and three-dimensional model simulations of two harbor systems. The combined focus on sediment-water exchange processes and estuarine exchange processes will provide much-needed constraints on contaminant transport rates. We are using Inner Boston Harbor as a representative of very sheltered harbors and New York Harbor as a test site to reveal the importance of sediment resuspension.