Visualization of oxygen concentration in water bodies using a fluorescence technique

Spatial variations of oxygen concentration were measured instantaneously in water body using the fluorescence intensity image technology. The movement of a fluorescent solution was visualized according to the oxygen concentration difference. Pyrenebutyric acid (PBA) was used as a fluorescence and a charge coupled-device (CCD) camera as an image detector. The calibration of fluorescence intensity as a function of oxygen concentration and temperature was utilized for a direct measurement of oxygen concentration at every pixel in an image of light intensity. Light intensity decreased about 40% while the amount of oxygen in water increased from zero to the air-saturated concentration (8.5 mg/l at 21°C), suggesting that the technique is sufficiently sensitive to determine the variation of oxygen concentration. Consecutive images of the oxygen content of a submerged jet solution were provided to quantify the spatial variation of oxygen in a water body. Analysis of these images also described the movement of solution, suggesting that the visualization technique could be applied more widely for research in experimental fluid flow and chemical transport in water bodies.