Citation

Sanchez-Espana J, Boehrer B, Yusta I. Environ. Sci. Technol. 2014; 48(8): 4273-4281.

Copyright

(Copyright © 2014, American Chemical Society)

DOI

10.1021/es5006797

PMID

24628479

Abstract

We quantify the gas pressure and concentration of a gas-charged acidic pit lake investigated in SW Spain. We measured total dissolved gas pressure, CO2 concentration, major ion concentration, isotopic composition of dissolved inorganic carbon (13CDIC) and other physico-chemical parameters. Carbon dioxide (CO2) is the dominant dissolved gas in this lake and mainly results from carbonate dissolution during the interaction of acidic water with wall rocks, followed by diffusive and advective transport through the water column. The 13CDIC values suggest that the biological contribution is comparatively small. Maximum CO2 concentrations higher than 0.1 molar (~5,000 mg/L) have been measured, which are only comparable to those found in volcanic crater lakes. The corresponding gas pressures of CO2 alone (pCO2~3.6 bar) imply 60% saturation relative to local pressure at 50m depth. High CO2 concentrations have been observed in other pit lakes of the region. We recommend gas-specific monitoring in acidic pit lakes and, if necessary, the design of feasible degassing strategies.

Language: en