Bioturbation-driven transport of hydrophobic organic contaminants from bedsediment

Compared to molecular diffusion the bioturbation-driven soluble fraction tr ansport for hydrophobic organic chemicals (HOCs) from bed sediment is rapid , and it increases with increasing partitioning on the particle phase. This behavior is supported by three sets of data: one is PCB from the Hudson Ri ver, NY, and the other two sets are PAHs and chlorinated benzenes in labora tory microcosms. The proposed mechanisms for this behavior are: (1) biotuba tion of particle-bound HOCs from depth through the upper decimeter of the b ed to the interface, (2) rapid chemical desorption at the sediment-water in terface followed by (3) transport through the benthic boundary layer to the water column. Based on this mechanism, a simple transport equation is deve loped, then used to correlate the data and extract intrinsic transport coef ficients. These in-bed particle biodiffusivities and benthic boundary layer coefficients are comparable to other reported measurements.