Influence of Biogenic Surfactants on Gas Exchange in the AirSea Interface

本研究将确定海水中表面活性剂影响海气界面气体交换速率的基本机制。表面活性剂通过改变近表面湍流的流体动力结构而不是通过形成单分子屏障来减少气体交换。在从合成表面活性剂到浮游植物渗出物的各种样品中，气体交换减少高达50%，这种减少发生在湍流条件下。本研究旨在对表面活性剂的化学和表面性质进行两步检查，因为它们与气体交换过程有关。首先，将在实验室风浪箱中探索气体交换系数Kw与表面膨胀模量、施密特数Sc和摩擦速度U*w之间的实验模型。其次，将描述海洋浮游植物渗出物的表面化学和有机化学及其对气体交换的阻碍作用。总体结果应该提高我们对生物来源的表面活性剂如何影响海洋中气体交换等物理过程的理解。

This research will define the basic mechanisms by which surfactants in marine waters affect the rate of gas exchange at the air-sea interface. Surfactants reduce gas exchange by altering the hydrodynamic structure of near-surface turbulence, and not by the formation of a monomolecular barrier. Reductions in gas exchange up to 50% have been observed in a variety of samples from synthetic surfactants to phytoplankton exudates and this reduction occurs under turbulent flow conditions. This research is aimed at a two step examination of the chemical and surface properties of surfactants as they relate to gas exchange processes. First, an experimental model relating the gas exchange coefficient Kw to the surface dilational modulus , the Schmidt number Sc and the friction velocity U*w, will be explored in a laboratory wind-wave tank. Second, the surface and organic chemistry of marine phytoplankton exudates will be described in relationship to their retarding effect on gas exchange. The overall results should improve our understanding of how surfactants of biogenic origin influence physical processes such as gas exchange in the ocean.