George Roadcap
Harold Henderson: Where were you working?
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GR: We started out looking at groundwater chemistry and contamination. The Water Survey has been studying that for years. I started in the early 1990s. We want to know what controls that chemistry–why some contaminants move and others don’t, especially the metals in the slag. I don’t want to give all slag a bad name. Iron slag left over from making pig iron is fairly innocuous. Steel slag is more reactive and contains more metals that are left over from making pig iron into steel. For instance, some steel slag can have as much as 2 percent chromium.
GR: If conditions are right they can consume metals and release them in forms that are soluble in water, thus potentially having a toxic effect on aquatic life. So I got interested in what bacteria might be growing there, if anything. The conventional wisdom was that little or no life could exist there because the pH is so high.
At first we didn’t have any good matches in the database with known alkaliphiles, but over the next couple of years researchers from California and Africa added new sequences, and we got some better matches. Some of the bacteria we found are related to Clostridium [e.g., tetanus] and Bacillus [e.g., anthrax] species, others are in the Proteobacteria class [a phylum that includes iron and sulfur bacteria].
HH: So they’re basically eating rust?
GR: Clearly some of them were imported from other places, because they’re closely related to bacteria in the other alkali areas. Others we found are related to bacteria you’d find in any wetland. They may be local bacteria that have adapted.
