Research Areas
Microsparger Probe for Real-Time Measurement of Volatile Compounds in Groundwater
The Microsparger, a groundwater probe capable of measuring groundwater concentrations of volatile compounds in the field in real time, is designed to fit in standard groundwater monitoring wells (U.S. Patent 6,420,187). The principle of the Microsparger probe is to equilibrate the groundwater containing dissolved volatile compounds with a small volume of air. Equilibrium is promoted by continuously spraying (vaporizing) the groundwater through the volume of air. The volatile compound concentrations are measured in samples collected from the gas phase contained within the headspace of the device, using commercially available gas analyzers such as a photo-ionizing detector gas chromatograph or photoacoustic infrared spectrophotometer for analysis. The concentration of the volatile organic compounds in the vapor can then be used to calculate the equilibrium concentration in the dissolved phase (Henry's Law). To calculate the equivalent concentration in water, the gas phase concentration, temperature, and the Henry's law constant for the constituent must be known. The temperature is measured directly (with a thermocouple attached to the Microsparger) and the Henry's law constant can be obtained from reference sources. The probe has a simple, straightforward design, is inexpensive, and easy to operate in the field.