不同底栖生物扰动对沉积物渗透性的影响

Influences of Bioturbations on Vertical Hydraulic Conductivity Diversity of Sediments

[目的]探讨不同生物扰动对沉积物成分、粒径分布和渗透性的影响,为河流污染治理与潜流带修复提供科学依据。[方法]通过室内模拟沉积物中摇蚊幼虫（Chironomid larvae）,颤蚓（Tubificid）和尖膀胱螺（Physa acuta）的生物扰动过程,研究不同底栖生物扰动对河流潜流带沉积物渗透系数的影响。[结果]混合生物组中,摇蚊幼虫和尖膀胱螺组合为渗透性能加强最大的一组。生物扰动作用通过改变沉积物的物理特性促使其结构疏松,孔隙增大,从而对沉积物颗粒粒径大小和分布区域产生明显干预作用,从而影响沉积物的渗透性。摇蚊幼虫对沉积物成分变化及粒径分布影响最大,使沉积物渗透性增强;颤蚓的淤塞作用主要发生在水-沉积物界面以下3～9cm,导致渗透性减弱;尖膀胱螺对沉积物粒径分布的影响不明显。[结论]在同一沉积物环境条件下,单一物种组中摇蚊幼虫和尖膀胱螺对沉积物的渗透性呈促进作用,摇蚊幼虫的促进效果比尖膀胱螺更显著,颤蚓对沉积物渗透性呈削弱作用。

[Objective]We analyzed the impact of bioturbations on sediment composition,particle size distribution and permeability in order to provide a scientific basis for river pollution control and undercurrent belt repair.[Methods]We investigated the effects of different invertebrates on vertical hydraulic conductivity（VHC）through simulating sediments distrubed by Chironomid larvae,Tubificid and Physa acuta in laboratory conditions.[Results]C.larvae and P.acutahad the greatest impact on permeability.The clogging effect by Tubificid mainly occurred in 3—9cm under water-sediment interface,resulted in reducing hydraulic conductivity.The granularity effect and distribution characteristics by P.acuta were barely discernible.[Conclusion]Bioturbation of both Chironomid larvae and Physa acuta improves the VHC of sediments,while bioturbation of C.larvaeis more remarkable,comparatively.In contrast,Tubificidweakens the permeability of sediment.Bioturbation can modify the structure of sediment deposits,and thereby promote the permeability of streambed sediments.