Institute of Water Security and Science
The evasion of CO2 from terrestrial waters plays a role in the global cycling of carbon but there are few datasets that have an accurate accounting of the flux. It has been shown that discharges from coal mines can have elevated concentrations of CO2 due to sulfuric acid-driven dissolution of carbonate rock. In this study, we compared three methods for calculating the export dissolved inorganic carbon (DIC) and the evaluation of CO2 from an abandoned-mine discharge in West Virginia. In Method #1, the source flux is calculated from the discharge and the concentrations at the portal. In Method #2, the stream flux is calculated over a stream reach and considers both upstream and downstream chemistries. In Method #3, the diffusive-flux model estimates evasion based on transport of CO2 through the water column. Methods #2 and 3 can be compared compared by knowing the area of the stream surface between the two measurement points. In general, the methods based on direct measurement of DIC and CO2 (Methods #1 and 2) were greater than the estimates the diffusive-flux model (Method #3). This comparison demonstrates the need for more direct measurements of CO2 if we are to account for carbon export from streams and mine waters.
Lee, KJ and DJ Vesper. 2021. Comparison of Methods for Estimating Carbon Evasion and Export Associated with a Coal Mine Discharge. IWSS Spring Workshop Series (Virtual).