Fig. 3.

Percent change in modeled chemical species after removing denitrification coupled to methane and sulfur oxidation from the optimized model. After calibrating the model to match the chemical and gene distributions with the additional processes, denitrification coupled to methane and sulfur oxidation rate constants were set to zero, but all other parameters remained constant. Chemical concentrations were summed over all depths and time points. Removing these processes most substantially impacts iron speciation likely because of the competition with iron oxidation for nitrate