The aim of this study was to investigate the influence of humic substances (HS) on volumetric oxygen‐transfer coefficient (K _La) under different turbulence intensities at the air–water interface. The experiments were carried out in an oscillating grid tank which provided three levels of turbulence intensities (Reynolds numbers of 5,116, 10,316, and 15,433). For each turbulence level, 15 different HS concentrations were tested and the K _La was estimated. The results showed that, regardless of the turbulence level in the tank, HS reduces K _La. The maximum reduction was 17%. The barrier effect, produced by the occupation of HS molecules at the interface, was the main phenomenon responsible for the reduction in the oxygen transfer. A relationship between the oxygen transfer velocity and turbulent kinetic energy showed that in the presence of HS, the air–water interface behaves like an immobile surface, reducing the oxygen diffusion and surface renewal.

中文翻译：

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腐殖质减少了空气-水界面中的氧气质量转移

这项研究的目的是研究在空气-水界面处不同湍流强度下，腐殖质（HS）对体积氧传递系数（K _L a）的影响。实验是在一个振荡式网格储罐中进行的，该储罐提供了三个水平的湍流强度（雷诺数分别为5,116、10,316和15,433）。对于每个湍流水平，测试了15种不同的HS浓度，并估计了K _L a。结果表明，无论罐中的湍流程度如何，HS都会降低K _L a 。最大减少量为17％。由HS分子在界面处的占据所产生的屏障效应是导致氧气转移减少的主要现象。氧气传输速度和湍动能之间的关系表明，在存在HS的情况下，空气-水界面的行为就像固定的表面，从而减少了氧气的扩散和表面的更新。