Carbonate Equilibria and Groundwater Sample Collection: Implications for Estimated Average Subsurface Properties in Continental North America

摘要

The geochemistry of carbon dioxide in oxygenated groundwater may have a profound impact on analytical results obtained from efforts to measurein situgroundwater pH conditions and on the speciation, partitioning behavior and potential transport of inorganic contaminants in aquifers. Based on the observation that an estimate of the mean, national-average groundwater pH changes from 6.65 to 6.83, depending on the delay time before analysis, a mechanism of pH alteration resulting from CO2degassing is examined to provide an estimate of the ratio between groundwater and atmospheric partial pressures of CO2(PCO2.GW/PCO2atm.= 1.5).