A novel approach for obtaining bubble dissolution measurements at sea: results

Abstract

A hybrid system for measuring the dissolution of gas bubbles in an oceanic environment was developed utilizing the Coastal Systems Station's Light Scattering Bubble Counter (LSBC). The LSBC independently measures flow velocity and bubble size, and is capable of distinguishing bubbles from particulate matter. In the hybrid system, the dynamic range of the LSBC measurements is 50 microns to about 300 microns in radius. The system is filled at depth in the sea, purged of all gas, and then closed from the outside environment. A steady now is established and clean air is forced through a porous ceramic disk to create the initial bubble population. This bubbly mixture is recirculated through the system at a constant flow rate of 22 liters per minute (LPM), or 33 LPM, corresponding to velocities of 30 cm/s and 45 cm/s through the LSBC aperture, respectively. The bubble radii are measured continuously using the LSBC, resulting in time-dependent bubble-size distributions. A numerical technique has been developed to estimate the dissolution rate from the bubble distribution time series.