The effect of water parameters on the corrosion of iron and iron recharge under anaerobic conditions was studied for all three sediment site waters. It was determined that a combination of factors like composition of water and pH significantly affects the corrosion of iron in water. In the case of Lake Hartwell site water, a gradual increase in pH and a cessation in H2 generation is observed after 4 months whereas the recharge systems continue generating H2 with each amendment. In the case of New Bedford Harbor site water, a similar trend is observed with the recharge systems sustaining H2 production and a cessation in H2 generation in the no recharge system. The Roxana Marsh site water exhibits higher pH values and greater H2 generation in the recharge sets when compared to Lake Hartwell and New Bedford Harbor. This suggests that iron corrosion occurred at a faster rate in the Roxana Marsh site water than the other two sites. In the case of Lake Hartwell, corrosion of iron is initially enhanced by the presence of HCO3- ions which gradually transform into CO32- ions at higher pH therefore passivating the surface of iron by precipitating as FeCO3. Research has shown the presence of sulfides to be associated with an increase in the corrosion rate of iron. Since relatively higher rates of sulfate reduction was observed in New Bedford and Roxana Marsh site water, the formation of FeS would have enhanced iron corrosion. At the same time, the presence of Cl- has been shown to be inhibitory to iron corrosion. Therefore, Roxana Marsh site water exhibits higher H2 generation via corrosion of iron when compared to New Bedford Harbor site water due to the presence of high concentrations of inhibitory Cl- ions in New Bedford Harbor. The effect of sulfides in enhancing corrosion is also evident in the lag times observed preceding a decrease in the alkalinity in the New Bedford Harbor and Roxana Marsh site waters.
In summary, the periodic amendment of iron to the site waters from three sediments sustained the corrosion of iron in water and resulted in continuous generation of H2, which is the primary electron donor for dehalorespiration. The periodic amendment of iron also resulted in a partial decrease in sulfate concentrations and soluble iron by the formation of insoluble sulfides, which aids in removing toxic HS- from the system.