Influence of Biogenic Surfactants on Gas Exchange at the Air-Sea Interface

点击翻译按钮获取中文摘要

FREW 9301334 Surface-active organic matter produced by marine phytoplankton is known to reduce the exchange of gases at the air-water interface. Surfactants have a first-order effect on the gas transfer velocity- wind speed relationship up to moderate wind speeds and the mean square wave slope offers a parameterization of transfer velocity Kw at different wind speeds and surface viscoelastic conditions. The objective in this continuing research is to further refine this parameterization for gas exchange in the presence of natural surfactants and to use surfactants as a tool to examine the role of small-scale waves and turbulence as agents affecting gas exchange. New techniques for characterizing 3-dimensional wave spectra and for measurement of viscoelastic damping will be applied to measurements of Kw in two circular wind-wave tanks of different scales. A range of surface-active compounds, including synthetic and natural surfactants, which yield films with different elastic and viscous contributions to the dynamic surface viscoelasticity will be used to modify the wave field during measurements of Kw and the three-dimensional wave spectra and gas transfer and to discriminate between mechanisms involving viscoelastic (marangoni) damping of either small scale wave or near-surface turbulence. The research is relevant to models of upper ocean biogeochemical processes in which gas exchange is an important component.