摇蚊幼虫扰动对沉积物-水微界面氧化还原特征的影响

生物扰动是影响沉积物-水微界面反应的重要因素,为了明确生物扰动作用对沉积物-水微界面氧化还原特征的影响机制,从环境微界面角度出发,以摇蚊幼虫为例,借助高分辨率的微电极系统解析沉积物-水微界面O_2、p H、氧化还原电位(Eh)的垂向分布特征。结果表明,摇蚊幼虫的生物扰动作用显著增加了沉积物-水微界面处的溶解氧浓度;降低了上覆水的p H值,提高了沉积物的p H值,且上覆水p H时空变化较大,沉积物p H值变化较小;廊道里O_2增加,使Eh值也相应地提高,而没有生物扰动到的地方Eh值偏低。摇蚊幼虫通过呼吸和摄食作用将富含氧气的上覆水引进廊道,充入的氧气改变了微界面的氧化还原条件。

Effects of the Chironomus plumosus on the redox characteristics of Sediment-water micro interface

Bioturbation is one of the important influence factors in the sediment-water interface reaction. To identify the influence mechanism of bioturbation on redox characteristics in the sediment-water interface, Chironomus plumosus is selected to examine its effect on the vertical distribution characteristics of O₂, pH and Eh using the high resolution microelectrode system. The result shows that the concentration of dissolved oxygen at the sediment-water interface is significantly increased, and the pH value of the overlying water is reduced together with increased pH value in the sediments. Moreover, due to the bioturbation of the Chironomus plumosus, the temporal and spatial variation of pH value in the overlying water becomes large, which is however less significant in the sediments. The Eh value appears to be significantly increased due to the increment of the Oxygen content in the corridor, which is low instead in the places without bioturbation. In general, the sediment-water micro interface is influenced by changing its redox conditions due to the oxygen, the latter is introduced into the corridor through breathing and ingestion of the Chironomus plumosus.