Multimedia fate modeling of polycyclic aromatic hydrocarbons (PAHs) in Lake Small Baiyangdian, Northern China

A QWASI (Quantitative Water Air Sediment Interaction) fugacity model was developed to characterize the fate and transfer of fifteen priority PAHs in Lake Small Baiyangdian. The PAH concentrations in the air (air, particulates), water (water, suspended solids, plants and fishes) and sediment (water and solids) as well as the transfer fluxes between adjacent compartments were derived under the steady-state assumption. Sensitivities of the model estimates to input parameters were tested. Monte Carlo simulation was conducted for the uncertainty analysis. The results indicate that there was generally good agreement between the modeled and measured concentrations with the differences within an order of magnitude for the majority of PAH components. The fluxes into and out of the lake as well as each compartment were well-balanced. The average bioaccumulation flux of PAHs by plants was four times higher than that by fishes. The transfer directions of PAHs were from air to water and to sediment. Temperature was the most influential parameter, and was more sensitive to the modeled concentrations of middle- and high-molecular-weight PAHs that were considered as the source of the model uncertainty. The model developed in this study could well characterize the fate and transfer of PAHs in the lake.