基于平面光极技术研究颤蚓生物扰动对水中Cd2+向沉积物迁移的影响

制备了一种能够选择性识别Cd~(2+)的平面传感膜;该膜具有响应速度快(20 s)、准确性高及稳定性好等特点。利用该传感膜制备的Cd~(2+)平面光极系统,应用于生物扰动存在的水/沉积物体系中,根据体系垂直剖面Cd~(2+)的分布及迁移情况,研究颤蚓生物扰动对上覆水中Cd~(2+)向沉积物迁移的影响。研究发现:制备的Cd~(2+)平面光极系统可以反映出上覆水中Cd~(2+)向沉积物迁移的过程。无生物扰动时,沉积物仅表层及水/沉积物界面下2 cm深度范围内第1~3 d的Cd~(2+)浓度略有升高,随后趋于稳定;深度超过2 cm的沉积物Cd~(2+)浓度几乎不变(同背景浓度)。有生物扰动时,深度约5 cm范围内的沉积物中Cd~(2+)浓度显著增加,深度越浅的沉积物中的Cd~(2+)浓度增加越快,深度超过5 cm的沉积物中Cd~(2+)浓度基本不变。与无生物相比,颤蚓扰动可以显著促进Cd~(2+)由上覆水中向沉积物的迁移。

Effects of Tubificid Bioturbation on Migration of Cd2+from Water to Sediment Using Planar Optode

A Cd₂₊ plane sensing membrane has been developed in this study, and the membrane has advantages including a short response time (<20 s), precise and good stability. With the help of camera, the sensor can directly show the variability in the distribution and migration of Cd₂₊ vertical profile in Water/Sediment System. The research indicates that the planar Optode applied to a simulated water/sediment microcosm can reflect the migration of Cd₂₊ from Water to Sediment. In addition, in the absence of bioturbation, the concentration of Cd₂₊distributed in the interface and the district within the depth of 2 cm from the interface of water/sediment was slightly increased in the first three days, and then tended to be stable. The concentration of Cd₂₊distributed in the district deeper than 2 cm from the interface of water/sediment remained constantly. Under the bioturbation, the concentration of Cd₂₊ distributed in the district deeper than 5 cm from the interface of water/sediment was increased dramatically. The amount of the Cd₂₊increased was inversely proportional with the depth, the concentration of Cd₂₊ distributed in the district deeper than 5 cm from the interface of water/sediment was remained constantly. Compared with the absence of bioturbation, tubificid biological disturbance can significantly promote the migration of Cd₂₊from water to sediment.