COI Funded Project: Surface Processes Controlling Aquatic-Atmospheric Gas Transfer in Estuarine Systems

Eugene Terray, Applied Ocean Physics and Engineering
Wade McGillis, Applied Ocean Physics and Engineering
Christopher Zappa, Applied Ocean Physics and Engineering

Proposed Research

Knowledge of air-water gas transfer velocities in aquatic and marine systems is essential to estimating the exchange of dissolved gases with the atmosphere. The magnitude of the gas flux for slightly soluble gases is dependent on the concentration difference across the air-water interface and the gas transfer velocity. Whereas concentration differences are readily measurable, it is only recently that advances in the understanding of surface boundary-layer transport processes have been applied to directly measure transfer velocities in the field. To date, this work has focused on horizontally homogeneous systems such as oceans and lakes, and has led to improved parameterizations of gas transfer velocity as a function of environmental forcing.

In contrast, estuaries and rivers are characterized by spatial and temporal inhomogeneity, which translates into a high degree of variability in the gas transfer velocity. As a result, to apply small-scale techniques developed for ocean use, mobile operations are required for estuaries.

The goal of this study is to develop the instrumentation and methodologies necessary for measuring estuarine and riverine gas exchange over a range of conditions. In connection with this effort, we will make field measurements of gas exchange in the Parker River estuary using gradient flux and controlled flux techniques from a mobile platform. These observations will be compared with an integrative measure derived from a deliberately injected tracer (SF6) to be carried out by the Ecosystems Group of the Marine Biological Laboratory.