颤蚓生物扰动对Cu和Cd从上覆水向沉积物迁移的影响

通过实验室模拟沉积物/水体系中颤蚓的生物扰动过程,研究颤蚓密度和上覆水pH对颤蚓生物扰动效应及其对Cu和Cd向沉积物迁移速率的影响.实验结果表明:颤蚓扰动作用可显著提高Cu和Cd向沉积物迁移的速率,且Cu受影响的作用大于Cd;随着颤蚓密度的增加,Cu和Cd的迁移速率均增大;酸碱胁迫均可促进生物扰动,碱性条件下生物扰动作用更显著;生物扰动促进的物质交换作用可显著增强实验体系对酸碱的缓冲能力,使体系pH趋于中性、均一;Cu和Cd的迁移速率同时受体系pH和扰动强度的影响,总体随上覆水pH值的增大而增加;生物扰动对Cd迁移的促进作用更大.

Effect of Tubificid Bioturbation on Migration of Cu and Cd from Overlying Water to Sediment

We studied the effect of tubificid density and overlying water pH on the behavior of tubificid bioturbation and on migration of Cu and Cd from overlying water to the sediment through laboratory simulation of sediment/water system in tubificid bioturbation processes. The results show that bioturbation can significantly increase the migration rate of both Cu and Cd to the sediment, and the effect increases with increased density of tubificid. The influence of bioturbation on migration rate of Cu is greater than Cd. Acid and alkali induced stress can enhance the bioturbation. This enhancement of bioturbation is more significant under alkaline conditions. The presence of tubificid bioturbation can significantlyenhance the acid base buffering capacity of the experimental systems, and makethe pH of systems to be uniform and neutral. Both the changes of pH and the bioturbation in the systems affect the migration rate of Cu and Cd.
Generally, the migration rate of the metals increases with the increase of overlying water pH. The promotion effect of bioturbation on migration rate of Cd is greater than Cu.