Towards accurate in situ dissolved gas concentration estimations in gas-charged groundwater using field measured total dissolved gas pressure (PTDG)

Date
2017
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Abstract
To date, there are currently no dissolved gas sampling standard operating procedures and total dissolved gas pressure (PTDG) is seldom utilized in dissolved gas sampling. This study assessed the accuracy of dissolved gas concentrations from common sampling approaches in eight gas-charged groundwater monitoring wells in central and southern Alberta, and investigated how measurement of groundwater PTDG can improve their success. Measurement of real-time, downhole PTDG while pumping was necessary in gas-charged groundwater to obtain in situ gas pressure that represented the formation around the well screen. Gas mass loss occurred by drawdown-induced ebullition and was unavoidable in the standing water column or pump tubing when gas-charged groundwater was pumped to surface for sampling. All four dissolved gas sampling approaches, but particularly gas-water separation, were susceptible to atmospheric contamination, which was sometimes associated with methane oxidation. This study highlights the need for improved gas sampling methodology to obtain accurate dissolved gas concentrations.
Description
Keywords
Geochemistry, Geology, Hydrology, Environmental Sciences
Citation
Evans, R. (2017). Towards accurate in situ dissolved gas concentration estimations in gas-charged groundwater using field measured total dissolved gas pressure (PTDG) (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/28476