• 关键词：沉积物  铅  释放  扩散梯度膜(DGT)  扩散通量模型(DIFS)

• 基金项目：国家自然科学基金资助项目(No4067100)

• 范英宏
• 北京交通大学土木建筑工程学院, 北京 100044

• 高亮
• 北京交通大学土木建筑工程学院, 北京 100044

• 赵国堂
• 北京交通大学土木建筑工程学院, 北京 100044

• 刘永娟
• 南京晓庄学院生物化工与环境工程学院, 南京 211171

• 摘要：采用扩散通量模型(DIFS)模拟了沉积物中Pb从固相向液相释放的动力学过程.模拟结果表明,对于扩散梯度膜(DGT)测定的Pb浓度C_DGT与孔隙水Pb浓度比值(R)接近1的S1样品,靠近DGT的液相Pb被消耗后,固相吸附态Pb迅速补给消耗;其解吸速率常数k_-1较大,而且非稳态Pb含量较大,在放置时间(t)内,DGT表面孔隙水Pb浓度一直维持在初始浓度.而对于R接近0的S2样品(无补给情况),靠近DGT孔隙水Pb被消耗后,固相的补给很少,反映在相关参数上便是非稳态Pb含量较低,而且解吸速率常数k_-1很小,DGT表面处孔隙水Pb浓度随放置时间的增加而降低.对于R值等于0.39的S3样品(部分补给情况),非稳态Pb含量和解吸速率常数k_-1介于S1和S2样品之间,固相的补给能力介于S1和S2之间.由以上模拟结果可知,沉积物中重金属释放动力学过程受到非稳态Pb含量和释放动力学参数共同影响.

• Abstract：A DIFSmodel was used to investigate the kinetics of release of Pb from sediments.The simulation results show that in a sustained case(sample S1,R→1),when the dissolved Pb adjacent to DGT(diffusive gradient in thin films) was depleted,the re-supply from the sediment was sufficiently fast to maintain the Pb concentration in the pore water to its initial level as the labile content of Pb and the desorption coefficient,k_-1 were high.For sample S2(R→0,a non-sustained case),the re-supply from sediment was very low,as the labile content of Pb was low and Pb concentration in the pore water adjacent to the DGTdevice was progressively depleted.For sample S3(a partial sustained case,R=0.39),the re-supply from sediment was between S1 and S2,as the intermediate labile Pb content and k_-1.As a result,the release of Pb from the sediments was influenced by the pool of labile Pb and the kinetic parameters of the release.

• Key words：sediment  Pb  release  DGT  DIFS

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