DETERMINATION OF A HYDRO-PNEUMOGRAPH IN A KARST SPRING

Many karst springs have been observed to ebullate (bubbling of free phase gases). However, scarce research has been conducted to quantify the rate and mechanisms of gas evolution. Presented in this work is the construction of a hydro-pneumometer (HPM) to simultaneously measure water and gas discharge from an ebullating (though non-effervescent) spring fed from the Arbuckle-Simpson aquifer. The construction of the HPM involves several sub-systems including a weir, gas capture system, gas conditioning system, and a thermal mass flow sensor. The gas system simultaneously measures the gas flux from the interfacial area of the water supersaturated with excess air under the capture shroud as well as the observable ebullating gas. The resulting data are plotted on a hydro-pneumograph allowing for the quantification of the mass flow of both phases of the spring discharge. Interestingly, the rate of gas discharge is higher during base flow conditions, consistent with previous observations related to dissolved phase excess air. Utilizing the hydro-pneumograph data in combination with dissolved and free gas chemical analysis, we hope to better define the mechanisms for the development of excess air over the flowpath to the springs.