再悬浮过程中河流底泥PAHs的迁移与释放

Delivery and Release of Sediment PAHs During Resuspension

利用再悬浮模拟(particle entrainment simulator,PES)装置模拟了河流底泥在受到上层扰动力后的再悬浮过程.结果表明,沉积物性质如粒径组成及PAHs含量对沉积物再悬浮过程中PAHs的释放影响显著.再悬浮过程中上覆水体总悬浮颗粒物(total suspended solids,TSS)含量与颗粒态PAHs之间存在极显著相关关系.切应力对再悬浮过程中PAHs释放的影响体现在两方面.一方面,单位体积的颗粒态PAHs随切应力增大而增大;另一方面,悬浮颗粒上PAHs的富集效应随切应力增大而减弱,是由于切应力强烈导致吸附作用弱的大颗粒进入水体.上覆水体中的PAHs总量在一段时间上升后于120 min或240min趋于稳定,而颗粒态与溶解态之间具有良好响应.高低环PAHs释放行为差异显著,由于中高环PAHs的疏水性,上覆水体中检测到的多为3~4环个体.

The resuspension of sediment after being disturbed is simulated by particle entrainment simulator( PES). The conclusions came out as follows. Sediment nature like granulometric composition and sediment PAHs richness markedly affected the release of PAHs. During the resuspension experiment,the total suspended solids( TSS) content of the overlying water showed significant correlation with particulate PAHs. The influence of the shear stress on the release of PAHs was reflected on two aspects. On one hand,its increase was accompanied with the increase of particulate PAHs. On the other hand,the PAHs enrichment effect of TSS decreased with the increase in the shear stress,since the stronger shear stress could draw more coarse particles with fewer PAHs into overlying water. The total PAHs in the overlying water continued to raise before stabilization at 120 min or 240 min. The particulate PAHs and dissolved PAHs answered each other very well. The release behavior among PAHs of different weight varied significantly. Due to the hydrophobic property of heavy weight PAHs,PAHs detected in overlying water were mostly 3-ring or 4-ring.