Iron (III) bioavailability during anaerobic biodegradation of organic pollutants in groundwater

摘要

The biodegradation of organic pollutants coupled to iron(III) reduction is an important and frequently observed process in the natural attenuation of anaerobic plumes in contaminated aquifers. However, microbial access to this oxidising capacity is limited since iron(III) mineral phases cannot be transported to or across bacterial cell walls. A brief review of current literature on iron reduction in groundwater reveals three hypotheses for electron transfer between microbe and iron(III) mineral surfaces. Iron reducing activity is 1) linked to attached growth, 2) depends on transport of dissolved iron(III) from the groundwater to the cell surface before enzymatic reduction and 3) electron transfer between the cell membrane and iron(III) sites is mediated by electron shuttles. This conceptual framework suggests that prediction and enhancement of the potential for natural attenuation by microbial iron(III) reduction will require assessment of the relative importance and interaction of cell wall physiology, the physical chemistry of cell-mineral surface interactions as well as the general geochemistry of the groundwater environment.