再悬浮作用下长江河口沉积物中Hg的迁移与释放  

Transfer and Release of Hg from the Yangtze Estuarine Sediment During Sediment Resuspension Event

作　　者：毕春娟[1] 陈振楼[1] 沈军[1] 孙玮玮[1] 

机构地区：[1]华东师范大学资源与环境科学学院,地理信息科学教育部重点实验室,上海200062

出　　处：《环境科学》2009年第11期3256-3261,共6页Environmental Science

基　　金：国家自然科学基金项目(40701164);“十一五”上海市重大科技攻关项目(07DZ12037);“十一五”国家重大水专项(2008ZX07317-006)

摘　　要：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 resuspension energy and duration on release and subsequent redistribution of sediment bound Hg in Yangtze Estuary was measured experimentally using a particle entrainment simulator. Concentrations of HgD （Dissolved Hg） and Hgv （Particulate Hg） in the overlying water were 34-268 ng·L^-1 and 25-195 μg·kg^-1 respectively, and sensitive to disturbance energy and time during sediment resuspension. There is no significant correlation between HgD and Hgp concentration. After the first disturbance intensity experiment for 3 h, Hg was released to the overlying water in general, with HgD and Hgp concentrations increasing from 179 ng·L^-1to 268 ng·L^-1 and from 116 μg·kg^-1to 139 μg·kg^-1respectively. And then concentrations of HgD and Hgpdecreased after the overlying water was disturbed for 3 h at the second intensity, while after the third disturbance intensity experiment for 3 h, a slight increase was observed in HgD , and Hgp concentration increased from 89μg·kg^-1 to 162 μg·kg^-1in overlying water. The distribution coefficient （lg Kd ） of Hg in overlying water had no significant correlations with the water column pH, Eh, DO and TSS, but influenced by the combined physical and chemical conditions of the water column. In each disturbance energy treatment, both the content of suspended particles and lg Kd for Hg increased rapidly in the overlying water in the early stage, especially the first 5 min, indicating a strong absorption of Hg on the suspended particles. After that, a decrease of the lg Kd for Hg occurred with the time and content of suspended particles increased. It can be explained that the released Hg by oxidation of sulfide was bounded by the newly generated colloidal material such as the hydrate iron-manganese oxide. In relatively strong disturbance energy treatment, part of the coarse particles settled with time. The concentrations of Hgp increased in some resuspension stage in the overlying water due to the ＂fine particle concentration effect＂.

关 键 词：再悬浮 HG 沉积物 河口 物理扰动 

分 类 号：X143[环境科学与工程—环境科学]