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Probing the microscopic life found in the submerged recesses of an abandoned Wisconsin lead and zinc mine, scientists from Argonne and the University of Wisconsin-Madison have found compelling evidence that microorganisms play a key role in the formation of mineral deposits.
The finding not only sheds light on biology's role in the formation of some metal ores, but could help jump-start new remediation efforts for contaminated mining sites.
Writing in the Dec. 1 issue of the journal Science, the researchers describe the discovery and characterization of natural biofilms that seem to concentrate zinc sulfide. The biofilms, found deep in an abandoned mine, are heavily populated with bacteria, some of which help convert sulfate or sulfuric acid, a pervasive contaminant associated with the mining of metal ores, and zinc from groundwater into zinc sulfide.
"These results show how microbes control metal concentrations in groundwater and wetland-based remediation systems and suggest biological routes for formation of some low-temperature zinc sulfide deposits," the researchers write in Science, the nation's leading scientific journal.
In their paper, the researchers described a process by which tiny zinc sulfide crystals rapidly accumulate within natural biofilms populated by species of sulfate-reducing bacteria. The reduction of sulfate to sulfide, according to Matthias Labrenz, the lead author of the Science paper, is linked to the oxidation of organic matter: as the microbes metabolize organic material, they release sulfide ions into the solution around the biofilm. This leads to saturation in the neighborhood of the biofilm and, as a result, zinc sulfide rapidly accumulates as microscopic crystals in the biofilm.
That very process is "what has been envisaged for acid-mine drainage treatment using constructed wetlands that are rich in organic matter. Maybe our work can be used to refine development of these strategies," according to Jillian Banfield, a University of Wisconsin-Madison professor of geology and geophysics and the leader of the research effort. Acid mine drainage is a threat to ground- and surface water near mines.
Working at the Advanced Photon Source, the research team used the most finely focused high-energy X-ray beam in the world to date to show that small but significant quantities of other toxic ions, arsenic and selenium, for example, as well as zinc, are extracted from groundwater and concentrated in the biofilms.
Another group, led by UW-Madison physics professor Gelsomina De Stasio, used a novel X-ray microscope to perform a chemical analysis showing that the sulfur compounds found in the biofilms were indeed sulfides.
"The capability of the microscope enabled us to determine that there are a lot of sulfates in the sample, everywhere, whereas localized on the bacterium was sulfide," De Stasio said.
What the researchers have found is a natural process by which microbes -- bacteria from a family known as Desulfobacteriaceae -- produce sulfide that scavenges zinc and other toxic metals from the surrounding groundwater.
In some cases, the newly discovered biofilms can bring zinc-rich solutions of groundwater "down to values well below safe drinking water levels," said Banfield.
At a more fundamental level, the discovery broadens scientific understanding of the role microbes play in the formation of mineral deposits.
"This is not just a skip forward," said Argonne's Ken Kemner (ER). "We've taken a very large step in understanding mineral-microbe interactions. The interaction of bacteria with solids is ubiquitous and has implications not just in geochemistry but in other areas from astrobiology to environmental science."
Other Argonne contributors to the Science paper include Barry Lai (XFD) and Shelly Kelly (ER). The work was primarily funded through the U.S. Department of Energy's Basic Energy Science Program. Funding was also provided by DOE's Office of Biological and Environmental Research.
Argonne-West's annual "Christmas for Families," taking place through Friday, Dec. 8, will help make holiday wishes come true for families throughout southeastern Idaho. There are three ways for employees to help those in need.
A tree on display in the Laboratory and Office Building Lobby is decorated with ornaments representing children who will be supported with Argonne-West donations. Each ornament has information about a child's sizes and needs. Employees are invited to remove an ornament and purchase the goods needed. Unwrapped gifts, along with the ornament, should be brought to Shelley Wray (RPS), Bldg. 710, no later than Friday, Dec. 8.
Each area representative has a large, colorful Christmas card designed to take the place of individual cards that employees might purchase for co-workers. Employees can donate the money that would have gone to cards to the Christmas for Families program.
A decorative box will be placed near the cafeteria cash register for employees to donate extra change.
Last year, Argonne-West employees donated $5,550 to 12 families and 37 children.
"Writing Research and Development Proposals," a two-day seminar, will be held at Argonne-East Monday and Tuesday, Jan. 29-30.
Participants will learn a systematic approach to creating a "winning" proposal using a successful, flexible process. The strategies are custom-designed for federally funded research and development centers.
The seminar will be useful for program directors and managers, engineers and scientists, technical support employees and legal, work-for-others and technology transfer employees.
The seminar, sponsored by Human Resources, will be held from 8:30 a.m. to 5 p.m. each day in Building 402, Room E1100. Cost is $750.
Registration deadline is Monday, Dec. 18. Register through a Training Management System representative.
Meteorologists are predicting a "normal" winter this year, colder and snowier than the last few. Winter weather has the potential to affect operations at both Argonne sites.
If heavy snow falls at Argonne-East during the work day, the chief operations officer, in conjunction with DOE management, may decide to close the site early. If this happens, employees should use extra caution when leaving the site since traffic is likely to be heavy and visibility poor.
When heavy snow falls early in the morning, Argonne-East employees may want to delay travel to the laboratory until roads have been cleared. Employees should discuss their options with their supervisors in advance and monitor broadcast weather reports.
If in doubt, Argonne-East employees can call the Argonne Info-Line at (630) 252-INFO. Employees with Internet connections at home may also check the Argonne home page, which will be updated as necessary with the latest information.
On arrival at the site, drivers may be directed to park in a designated area to allow the parking lots to be cleared.
Chicago-area radio stations will not be provided with late opening or laboratory closing information for Argonne-East.
Argonne-West
The Idaho National Engineering and Environmental Laboratory (INEEL) has a toll-free phone number employees can call to find out about changes in bus routes or schedules due to weather: (877) 424-4635. INEEL Bus Operations will record weather-related changes as soon as they are made.
The number was established because radio and television broadcasts have been unreliable. The phone number has been made available to broadcast stations so they can broadcast bus-operation information if they choose.
Winter footwear
Each year employees at both sites suffer injuries due to slips and falls. This is the time of year to anticipate that walkways may be icy. The use of non-slip shoes may prevent a painful injury.
Drivers at Argonne-East should use extra caution this time of year, as the arrival of winter increases risk of colliding with a deer on the site's roads.
Both fallow and white-tailed deer are more active during mating season, especially bucks.
The early arrival of darkness reduces visibility and drivers' reaction times. Falling snow may further reduce visibility and make it harder to stop in time to avoid a collision.
Northgate and Westgate roads, where trees line both sides of the pavement, can be especially hazardous.
The Argonne Pioneers will sell snowbrush-scrapers Wednesday, Dec. 13, through Monday, Dec. 18, in Argonne-East's Building 213 Cafeteria at lunchtime.
The brushes are white with the stylized "running deer" logo of the Pioneers. Brushes are $5 each.
The Pioneers are an organization of retirees and employees who have worked at Argonne 30 years or more.
An open meeting to inform the public about proposed changes to the State of Illinois' permit for hazardous-waste handling at Argonne-East will be held Thursday, Dec. 7, at 7:30 p.m. in the Advanced Photon Source Auditorium.
The focus of the meeting is a proposal by Argonne and DOE to move some containers of hazardous waste from a concrete pad in the 317-319 area, which is undergoing environmental remediation, to a pad near Building 331. This use of the Building 331 pad requires a change in the lab's hazardous-material-handling permit from the Illinois Environmental Protection Agency.
After the meeting, DOE and Argonne experts will be available to answer questions about the permit and all other aspects of Argonne's programs in environmental cleanup, waste handling and management, and emergency preparation and response.
More information is available on the Web or by contacting Brian Quirke (DOE-CH) at ext. 2-2423.
A Fannie May candy sale will be held in the Argonne-East Building 213 Cafeteria at lunchtime Tuesday, Dec. 5, through Thursday, Dec. 7.
Sponsored by Sodexho Marriott, the sale will feature candy priced at 15 percent off the retail price.
The Argonne Choral Group will sing holiday carols Thursday, Dec. 7, at noon in Argonne-East's Building 213 Cafeteria and at 2 p.m. in the lobby of Building 201.
The group marks its 20th anniversary this year.
A representative from MetLife will visit Argonne-East Tuesdays, Dec. 5, 12 and 19, to meet with employees individually for insurance comparisons and quotes for the "METPAY" group automobile and homeowners insurance program.
To schedule an appointment with the MetLife representative, call Craig Riddick at (630) 810-0346, ext. 143. Before each meeting, Argonne employees should fax their auto policy renewal statements to (630) 810-1628.
The METPAY program is voluntary. Participants can obtain group automobile and homeowners coverage at rates not available for similar policies purchased through the individual insurance market.
