Dissolved oxygen is a common parameter measured in groundwater. It can be used for baseline measurements, to help determine when to take a sample during low flow purging, and to help understand pollution plume movement and remediation. Over the last 50 years, there have been many technological advances in the measurement of dissolved oxygen beginning with the invention of the Clark Electrode by Dr. Leland Clark in 1956. This invention allowed for rapid detection of dissolved oxygen in an aqueous solution for the first time. Over the years, the Clark Electrode was much improved upon culminating in the invention of a stirring independent Rapid PulseTM Polarographic sensor. Other advancements of the Clark Electrode include the availability of several different types of membranes and electrode material options for steady-state sensors that enhance an electrode’s overall performance. In the last few years, the method for measuring dissolved oxygen has advanced even further with the introduction of optical-based sensors packaged in portable sampling devices.
Today, there are several different types of Dissolved Oxygen sensors available for groundwater sampling and monitoring applications. The sensor options include steady-state electrochemical - both Polarographic and Galvanic, Rapid Pulse Polarographic, and Optical which is also referred to as luminescent. Each sensor type detects dissolved oxygen using different methodologies; therefore, there are advantages and disadvantages associated with each sensor. An understanding of how these sensing methods differ can help determine which option is best suited for a particular application and potentially lower project costs. This session will describe and compare the different DO sensing technologies.
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