Anaerobic Degradation of Benzene was Enhanced through Sulfate Addition Substantially Increasing the HC Degradation Rate at a Central Indiana Site

摘要

At this Central Indiana site, dissolved BTEX levels were relatively high fifteen years after the service station closed. Despite the facts that the UST source area had been over excavated at the time the facility closed and a pump and treat system had operated for a period of time, concentrations were still too high to qualify for MNA. In 2004, dissolved benzene levels near the source area hovered at 1000 ppb. The dissolved plume was neither growing nor shrinking. If the source area could be addressed, the plume should shrink. Excavation was not an option because the site had already been redeveloped. Inorganic analyses showed that dissolved sulfate was present naturally in the aquifer outside the hydrocarbon plume with a mean concentration of 78 mg/1. In the dissolved phase BTEX plume area, however, sulfate concentrations were substantially reduced to concentrations less than 10 mg/1. Additionally, a shadow of reduced sulfate concentration extended downgradient of the plume area.