Phenanthrene sorption to tidal sediments from the Yangtze River Estuary

Phenanthrene was chosen as a probe compound and representative of PAHs to determine equilibrium sorption isotherms for tidal sediments from the Yangtze River Estuary. To study the factors that influence the sorption process, sorption experiments were performed at different salinities, nutrient salt concentrations and temperatures and with different sediment fractions. The results showed that the Freundlich model fit the experimental data well. With the increased TOC contents, K_Fr values increased, while n values decreased. Salinity had slight impact on the sorption, but no influence was seen for samples with low TOC. Moreover, nutrient concentrations did not show significant influence on the sorption isotherms. Sorption capacities grew slightly higher at higher temperature, but the n values were stable. Samples were treated sequentially to remove inorganic and organic carbon. Sorption experiments with treated samples showed that the contribution of the inorganic carbon to the total sorption was insignificant, while organic carbon (OC) played an important role in the total sorption. OC controlled the whole sorption in Wusongkou(WSK)samples with TOC>1%; whereas for Laogang(LG) samples with 0.1%<TOC<1%, OC dominated the sorption at relatively high C_w, while it contributed less than 50% of the total sorption at lower C_w concentrations.