This study intends to use a petroleum contaminated site with Fe-Mn nodules in Henan oil field as a study area, study on the environmental geochemical evolutionary mechanism of the Fe-Mn nodule as electron acceptor, take the spatial analysis, adsorption/desorption experiments, column simulation test system, microbial identification and testing methods, reveal the mechanism of heavy metal ions leaching from Fe-Mn nodules and petroleum pollutants degradation, clarify the transition and transform rule in the interaction process, evaluate the control function and contribution rate of microorganism in the process.
We carried out microcosm experiments to examine the capacity of iron--manganese nodules to remove petroleum compounds at 15°C, which is close to the temperature of the aquifer. In the experiments about 81% of the crude oil disappeared, the nodules released at highest 90.14, 8.27, and 0.006 mg/L of Fe, Mn, and As, respectively, almost 16% of the iron--manganese nodules dissolved. Contrasted with the autoclaved controls, the microbial reduction of Fe and Mn and release significant amounts of As, Ba. The results indicate that iron--manganese nodules maintain rich, distinct bacterial communities under oil exposure that have the potential to remove petroleum compounds in anoxic conditions, while released Fe, Mn, As, etc, which has a potential hazard to groundwater.