动水条件下重金属在沉积物-水之问的迁移规律

摘要

借助自主开发的不同水动力模拟水槽,选择4.01 cm/s(小流速,A槽)、12.70 cm/s(中流速,B槽)、20.23 cm/s(大流速,C槽)3种流速条件,研究15d运行周期内,3个水槽中沉积物重金属Cd、Cr及类金属As在沉积物-间隙水-上覆水之间的迁移规律.结果表明:1)流速的增加能促进重金属的释放；2)间隙水中As的浓度远远大于上覆水中浓度,为其向上覆水迁移提供了条件；3)沉积物再悬浮是上覆水中重金属浓度增加的主要原因.同时,与静水条件相比,动水条件对沉积物中重金属的迁移有显著影响,但不同重金属受自身特性的影响显示不同的迁移规律.另一方面,3种水流条件对不同介质中重金属含量变化产生的影响过程和结果也不相同,但其影响程度总体为上覆水＞沉积物＞间隙水.%The mobility of heavy metals including Cd,Cr and As,among sediment,pore water and overlying water under different hydrodynamic conditions in 15 d was analyzed with hydrodynamic flumes.Three velocities were designed as 4.01 cm/s for slow flow in Flume A,12.70 cm/s for middle flow in Flume B,and 20.23 cm/s for fast flow in Flume C.Results show that; 1) Increasing the velocities of flow can promote the release of heavy metals; 2) As of pore water presented higher concentration,which shows the mobile trends of As are from pore water to overlying water; 3) Sediments suspended are the main reason for the increase of concentration of heavy metals in the overlying water.Compared with the static condition,hydrodynamic conditions significantly affect the mobility of heavy metals.And the changing characters in each flume are different for each kind of metals in different kinds of medium (overlying water,pore water,and surface sediment).Moreover,the extent of hydrodynamic impacts on the mobility of heavy metals is overlying water>sediment>pore water.