基于涡动相关法的沉积物-水界面氧通量与水动力条件响应关系

沉积物-水界面是物质参与环境地球化学循环和生物耦合的"热区",水动力条件是沉积物-水界面物质交换的关键影响因素。溶解氧作为常用的水质评价指标,对调节生物化学进程有重要作用,因此本文采用涡动相关法这种非侵入式通量测量技术开展室内试验研究,探究沉积物-水界面氧通量与水动力条件的响应关系。结果表明:随着水体紊动增加(采用Batchelor尺度表征),扩散边界层厚度减小,氧通量增大。分析室内试验和相关研究中水动力条件、扩散边界层厚度及氧通量的关系,发现扩散边界层厚度与Batchelor尺度呈正相关关系,拟合结果表明可以用Batchelor尺度近似表示扩散边界层厚度;氧通量与扩散边界层厚度呈负相关关系,且当扩散边界层厚度小于0.5 mm时,扩散边界层厚度变化对氧通量影响更强烈,当厚度大于0.5 mm后,氧通量基本保持稳定。

Relationship between oxygen flux of sediment-water interface and hydrodynamic conditions based on eddy correlation method

Sediment-water interface is a "hot zone" in which material participates in environmental geochemical cycles and bio-coupling. Hydrodynamic conditions are the key factors affecting sediment-water interface material exchange. Dissolved oxygen as an important water quality evaluation index plays an important role in regulating biochemical processes. Therefore, to explore the relationship between oxygen flux of sediment-water interface and hydrodynamic conditions,the eddy-correlation technique,a non-invasive flux measurement technique was used in laboratory test. The results showed that diffusive boundary layer thickness decreased with increasing hydrodynamic conditions (characterized by Batchelor scale), while oxygen flux increased. By analysing of the relationship between hydrodynamic conditions, diffusive boundary layer thickness and oxygen flux in laboratory and related studies,there is positive correlation between diffusive boundary layer thickness and Batchelor scale, and the fitting relationship shows that the diffusive boundary layer thickness can be represented by the Batchelor scale. The oxygen flux is in negative correlation with diffusive boundary layer thickness. The diffusive boundary layer thickness variation has a strong influence on the oxygen flux when less than 0.5mm of diffusive boundary layer thickness, while the thickness is more than 0.5mm,the oxygen flux remains basically stable.