Quantifying the Possible Short- and Long-term Impacts of Superoxide Redox Chemistry on Seawater pH

We show here that the redox chemistry of superoxide (dismutation, oxidation and reduction), involving exchange of H+upon reaction with some metals and organic compounds, is potentially able to alter the pH of seawater at time scales of several months to some years. The relevant pH effect could be locally significant in river-impacted coastal areas, where lower alkalinity compared to the open ocean combines with inputs of terrestrial matter that might produce imbalances in superoxide redox chemistry. The related effect may act as a local confounding factor in the assessment of seawater acidification.