The role of sediment resuspension duration in release of PAHs

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants. Due to their low water solubility and high hydrophobicity, PAHs are rapidly sorbed onto particles and subsequently deposit in sediments once introduced into aquatic environment. In such a way, sediments become a huge sink for PAHs. During sediment resuspension, the potential exists for PAHs to be released from sediments into water. Sediment resuspension plays an important role in the transportation and fate of PAHs in the aquatic environment. In this study, release behavior of PAHs on Yangtze River sediment during resuspension was investigated using a particle entrainment simulator (PES). The role of resuspension duration on release of 16 PAHs was measured by resuspending sediment for 12 h at 0.2 and 0.5 N/m², respectively. Results indicated that PAH concentrations in TSS increase over time with more increase of phenanthrene and 4-ring PAHs. Comparing with 0.2 N/m² (30%), ΣPAHs concentrations in TSS demonstrated remarkable increase during 0.5 N/m² resuspension (37%). Dissolved PAH concentrations increased throughout the duration with more increase of 2–3 ring PAHs (50%–88%). Dissolved PAH concentrations showed remarkable increase during 0.5 N/m² resuspension (50%). Moreover, PAH concentrations in overlying water throughout the duration of resuspension were higher than toxic effects threshold values in drinking water developed by WHO, which may cause toxic effect on ecosystem. Supported by the National Basic Research Program of China (973 Project) (Grant No. 2003CB415204) and National Natural Science Foundation of China (Grant No. 40701166)