Four Ways Your DO Measurements Are Being Affected

By Kevin Westerling,
@KevinOnWater

There are several factors that affect the measurement of dissolved oxygen.  Some of these variables include temperature, salinity, flow or stirring dependence and barometric pressure.

Temperature and salinity are compensated for during instrument calibration and field use with the use of additional sensors and/or instrument software settings.  The effect of flow dependence has been overcome by advances in measurement technologies. Newer, optical dissolved oxygen sensors have no flow dependence.  For electrochemical based sensors, users need to provide sample movement to overcome flow dependence or the measurements could be artificially low.  Barometric pressure primarily affects the calibration of dissolved oxygen sensors as it defines the pressure of oxygen in the calibration environment.  If calibrated properly, there is generally no need to be concerned about changes in barometric pressure that take place after calibration or to recalibrate during the day.

All of these variables can have an effect on your DO readings and we’ll explore them further in this article.