Polycyclic aromatic hydrocarbons partition in particle-water interface in the Yangtze Estuarine and nearby coastal areas

Based on polycyclic aromatic hydrocarbons (PAHs) field data of particle phase and dissolved phase, partition coefficients K_p in particle-water interface from the Yangtze Estuarine and nearby coastal areas were obtained. The results show partition coefficients of PAHs in dry season were higher than those in flood season, and all of them ranged from 507 L/kg to 10 179 L/kg, increasing with the rise of PAH compounds. The linear free-energy relationship coefficients between K_oc value and octanol-water partition coefficients K_ow in dry season and flood season were 0.82 and 0.68, respectively. These relationships inferred that suspended particle matters in the Yangtze Estuarine and coastal areas had weakly lipophilic characteristics and adsorption ability. lgK_oc values of PAH compounds in the different sampling sites were higher than the upper limit value predicted by the classic equilibrium partition model. The partition processes of PAHs were not controlled by concentrations of suspended particle matters, particle grain sizes, overlying water salinity and dissolved organic carbon (R² <0.1), but influenced by particle organic carbon and heterogeneous mixtures of particle soot carbon. The expanded partition model which included soot partitioning could well predict in situ partition processes of PAH compounds whose octanol-water partition coefficients lgK_ow was lower than 6.