Illinois groundwater scientists have found microbial communities thriving in the slag dumps of the Lake Calumet region of southeast Chicago where the water can reach extraordinary alkalinity of pH 12.8. That's comparable to caustic soda and floor strippers -- far beyond known naturally occurring alkaline environments.
The closest known relatives of some of the microbes are in South Africa, Greenland and the alkaline waters of Mono Lake, California.
"Other alkaline communities have been found at pHs up to 11," says Illinois State Water Survey hydrogeologist George Roadcap. "That's sort of the high end of known natural communities."
Roadcap and his colleagues at the University of Illinois Champaign Urbana came upon the microbes while studying contaminated groundwater created by more than a century of industrial iron slag dumping in southern Illinois and northern Indiana. Roadcap will present details of what appear to be the most alkaline-tolerant life known to date on Tuesday, Nov. 4 at the annual meeting of the Geological Society of America in Seattle, WA.
Genetic analyses at one site revealed bacteria related to Clostridium and Bacillus species. These are found in highly alkaline waters of Mono Lake, tufa columns in Greenland, and cement-contaminated groundwater in a deep gold mine in Africa. Some RNA sequences appeared most closely related to thermophilic, or "heat loving," bacteria found in other parts of the world. The temperatures of the slag dumps are not extraordinary at all, of course. In fact they get pretty cold in the winter, driving the pH even higher, says Roadcap.
At five other sites the dominant microbes belonged to the Proteobacteria class including a large number from the Comamonadacea family of the beta subclass. "In high-pH microcosms experiments, one of these microbes
Contact: Ann Cairns
Geological Society of America