Scientists at the Idaho National Engineering and Environmental Laboratory are developing a chemical tracer technique to map the underground abundance of iron oxide-rust-that provides the ideal home for pollution-eating bacteria.

Their technique represents an important step toward better harnessing the bacteria to clean up heavy metals, organic chemicals, and radioactive contaminants polluting soils and aquifers and threatening water supplies.

Biogeochemist Robert W. Smith has been awarded a three-year $600,000 grant by the Department of Energy's Natural and Accelerated Bioremediation Research (NABIR) Program to develop a method to determine subterranean surface areas available to feed and house microbes. This mapping method will also enable researchers to track how bacteria move through the earth.

Harnessing the activity of microbes in contaminant clean-up is the basis for bioremediation. Bacteria can immobilize or destroy hazardous chemicals in polluted environments. To use microbes effectively, researchers need a greater understanding of how they interact with their environment.

Measuring available surface area will allow researchers to assess the bioactivity and movement of the microbes. "If you take organisms that do specialized bioremediation activities and inject them into the ground," Smith said, "how do they move to the places you want them to?"

The key to measuring surface area for microbes is measuring iron oxide, a common mineral found layered in soil everywhere. Iron oxide not only provides a surface for the microbes, but contaminants and bacterial nutrients interact with it in various ways. Microbes that travel through the ground--and potentially remediate soil contamination--stick to iron oxide, and certain kinds of bacteria use iron oxide like we use oxygen, said Smith.

Currently, researchers use averaged information about the extent of iron oxide layers derived from core samples, he said. The core samples are removed from
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Contact: Mary Beckman
beckmt@inel.gov
208-526-0061
DOE/Idaho National Laboratory
28-Oct-1998