颤蚓及其生物扰动对表层沉积物微环境 pH 和溶解氧的影响

摘要

以颤蚓为扰动生物，通过室内模拟实验，借助微电极研究颤蚓孔穴附近沉积物微环境pH 和溶解氧(DO)的高分辨率分布及变化规律.结果表明：沉积物的 pH 值随扰动时间延长先升高后降低，颤蚓扰动对 pH 值的降低有抑制作用；当扰动时间相同时，颤蚓使沉积物表面的 pH 值以颤蚓孔穴为中心出现下降(最多达0.3 pH 单位)，该下降作用可影响孔穴周围半径1 mm 的范围；无生物体系中的水-沉积物界面附近 DO 值随时间延长逐渐降低，但颤蚓的扰动作用使孔穴附近沉积物表面的 DO 值在水平方向上升高(可升高9.2~17.0μmol/L)，并增加 DO 的渗透深度，使最大渗透深度从3 mm 增加到5 mm.因此，沉积物中的颤蚓可通过改变沉积物微环境 pH 和 DO 的分布特征，进而影响水-沉积物界面附近污染物的环境行为.%Tubificid was selected as the bioturbator.High-resolution distribution and variation of pH and dissolved oxygen (DO)in the microenvironment of sediment near the tubificids’burrows were investigated by laboratory simulation experiments via microelectrodes.The results indicate that the pH value of sediment increased with time going at first,and then decreased.The bioturbation of tubificids had an inhibitory effect on this decrease of pH value.At the same bioturbation time,the surface pH value of the sediment around the tubificid burrows declined (up to 0.3 pH units).This effect of declining could become effective in an area of 1 mm radius around the burrows.Without tubificids,DO value level of the microenvironment near water-sediment interface decreased with time going.In the presence of tubificids,the DO value level near the water-sediment interface around the tubificid burrows increased (increased by 9.2—17.0 μmol/L ) in the horizontal direction. The penetration depth of DO also increased,and the maximum penetration depth increased from 3 mm to 5 mm.Therefore,the presence of tubificids would affect the contaminants in the water-sediment interface by changing the distribution and variation pattern of pH and DO of the sediment microenvironment.