Dissolved Oxygen and Oxidation-Reduction Potentials in Ground Water

摘要

Water samples were collected from various depths in a pristine sand and gravel water table aquifer at monthly intervals over a period of one year. Dissolved oxygen concentrations were near saturation 9 feet below the water table and decreased to nearly zero at 78 feet below the water table. Changes in the Eh values were consistent with changes in the dissolved oxygen concentrations. Hydrogen peroxide was detected in nanomolar concentrations at all depths, but not on every sampling run. Of all oxidation-reduction potentials calculated from substituting analytical results into the Nernst equation, only the Fe(3+)/Fe(2+) couple in the deepest well agreed with the measured Eh within 50 millivolts. The concentration profiles of many solutes, including dissolved oxygen, suggest mixing of shallow and deep ground waters. The observed concentration profiles were relatively constant over the duration of the sampling.