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利用PES(particle entrainment simulator)装置,实验测定了不同的扰动强度和时间对长江口沉积物结合Hg释放和再分布的影响.在再悬浮过程中,上覆水中HgD(溶解态Hg)和HgP(颗粒态Hg)随扰动强度和扰动时间发生变化,含量分别在34~268ng.L-1和25~195μg.kg-1之间,HgD和HgP含量相关性不显著.经一级扰动强度扰动近3 h后,上覆水中的Hg总体上存在释放,HgD含量从扰动前的179 ng.L-1增加到了268 ng.L-1,HgP含量仅有略微增加,从116μg.kg-1增加到了139μg.kg-1.经二级扰动强度扰动近3 h后,上覆水中HgD和HgP总体上减少了,而经三级扰动强度扰动近3 h后,上覆水中HgD又有略微增加,HgP含量也从89μg.kg-1增加到了162μg.kg-1.上覆水中Hg分配系数(lgKd)与水体的pH、Eh、DO、TSS均没有显著的相关性,而是受水体中各种物理、化学性质的综合影响.当扰动强度增大后,在再悬浮初期尤其前5 min之内,上覆水中悬浮颗粒含量迅速增加,Hg的lgKd也迅速增大,悬浮颗粒对溶解态Hg产生了强烈的吸附作用.之后随扰动时间的延长和悬浮颗粒含量的增加,Hg的lgKd值降低,由硫化物氧化释放的Hg被新近生成的铁锰水合氧化物等胶体物质结合.在较强动力条件下,随扰动时间延长,部分粗颗粒会发生沉降,“细颗粒浓缩效应”使上覆水中HgP含量增加.
The effect of different disturbance intensity and time on the release and redistribution of Hg in the sediments of the Yangtze Estuary was experimentally determined by means of a particle entrainment simulator (PES). During the resuspension, HgD (dissolved Hg) and HgP The particle size Hg changed with the disturbance intensity and the disturbance time, and the contents of HgD and HgP were 34 ~ 268ng.L-1 and 25 ~ 195μg.kg-1 respectively.The correlation between HgD and HgP content was insignificant After 3 h, Hg in the overlying water was generally released, and the content of HgD increased from 179 ng.L-1 before disturbance to 268 ng.L-1. The content of HgP increased only slightly from 116 μg.kg-1 to HgD and HgP in the overlying water decreased generally after disturbed by the intensity of second-order disturbance for nearly 3 h, while the HgD in the overlying water slightly increased after the third-order disturbance intensity perturbed for nearly 3 h, while HgP The content of Hg partition coefficient (lgKd) in overlying water was not significantly correlated with the pH, Eh, DO and TSS of water bodies, but was affected by various physical , The chemical properties of the integrated impact.When the disturbance intensity increases, in the initial resuspension, especially within the first 5 min, the suspended particles in the overlying water rapidly increased LgKd of Hg and Hg increased rapidly, and suspended particles strongly adsorbed Hg dissolved in Hg. After that, the lgKd of Hg decreased with the increase of disturbance time and the content of suspended particles. Hg Newly formed ferromanganese hydrate oxide and other colloidal substances.Under the conditions of strong dynamic, with the disturbance time prolonged, part of the coarse particles will settle, “fine particle concentration effect ” in the overlying water HgP content increased.