April 2007, Vol. 19, No.4

Research Notes

Ecosystem of Vanishing Lake Yields Valuable Bacterium

A never-before-seen bacterium found in the salt flats near a slowly vanishing lake may be instrumental in removing polluting nitrates from wastewater.

A team of researchers from Montana State University (MSU; Bozeman) have a bacterium that could clean up some pollution, according to an MSU news release. In three scientific papers currently being written, chemical engineering professor Brent Peyton, his students, and collaborators are describing the unique qualities of Halomonas campisalis, a bacterium Peyton discovered in 1995 near Soap Lake, Wash.

At the time of discovery, Peyton worked for the Pacific Northwest National Laboratory (Richland, Wash.), which wanted to develop a treatment to remove nitrate contaminants from alkaline and saline radioactive wastewater. Such a treatment also could be used to clean up wastewater from fertilizer- and explosive-manufacturing plants, which is 10 to 15 times saltier than the ocean and laden with polluting nitrates, according to the press release.

Peyton hoped the salty ecosystem of Soap Lake might be home to a bacterium that could live in such high-salt waters and also find nitrates appetizing.

Soap Lake is one of only 11 known meromictic lakes in the United States. Meromictic lakes have separated layers of differing mineral concentrations. The upper layer of Soap Lake is a little less than half the saltiness of the ocean but more than 100 times saltier than river water. The bottom layer is more than twice as salty as the ocean and more than 700 times saltier than river water. These two layers are thought to have remained unmixed in any significant way for the past 2000 to 10,000 years, according to the news release.

Soap Lake is located near salt flats, and water seeping through these flats finds its way into the lake, carrying salt with it. Peyton collected some mud from these flats in 1995, and in the lab, he tried to make something grow, and something did — the bacterium he would later name Halomonas campisalis.

Making its home in super-salty water, Halomonas campisalis eats nitrates, and when it has digested its meal, it gives off nitrogen as waste, the news release states. The bacterium was ideal for the treatment of salty, nitrate-bearing wastewater, as well as wastewater from the production of explosives and fertilizers.

“You could pour that salty wastewater in a tank with Halomonas campisalis, add sugar or vinegar for food, and let it perk away to create nitrogen,” Peyton said.

It could take years more for the bacterium to be turned into an industrial process, something Peyton hopes a company will attempt in the future, the news release states.

For more information, contact Peyton at bpeyton@coe.montana.edu.

USGS Study Reveals Endocrine-Disrupting Compounds in Fish

The U.S. Geological Survey (USGS) recently completed a study of the water quality of the Potomac River after noting a high incidence of intersex smallmouth bass — male fish exhibiting female characteristics. According to a USGS news release, scientists found pesticides, flame retardants, and personal-care products containing known or suspected endocrine-disrupting chemicals in several tributaries to the Potomac River and in the smallmouth bass that inhabit them.

According to USGS, endocrine disrupters in the environment include pharmaceuticals in untreated wastewater and agricultural runoff. Endocrine disrupters of this type may contribute to the high percentage of male smallmouth bass found in the Potomac that exhibit female characteristics, USGS said.

“We analyzed samples of 30 smallmouth bass from six sites, including male and female fish without intersex and male fish with intersex,” said Douglas Chambers, USGS scientist and lead investigator. “All samples contained detectable levels of at least one known endocrine-disrupting compound, including samples from fish without intersex.”

Known or suspected endocrine-disrupting chemicals from pesticides, flame-retardants, and personal-care products were also present in water samples taken from all eight sites, including those where fish did not exhibit intersex, the news release states.

Wastewater from several sites that discharge municipal effluent or from sites contributing runoff was examined to identify point sources of these compounds. Antibiotics were found in wastewater samples, with municipal effluent having at least seven such compounds, but were not detected in water from other sites, scientists found.

The report, A Reconnaissance for Emerging Contaminants in the South Branch Potomac River, Cacapon River, and Williams River Basins, West Virginia, April–October 2004, is available at pubs.usgs.gov/of/2006/1393.

‘Hidden Hero’ Microbes in Soil, Water May Help Clean Toxic Sites

The Oak Ridge (Tenn.) National Laboratory’s Y-12 National Security Complex is about to get a good cleaning.

Since the 1950s, toxic waste dating from a weapons manufacturing facility has been leaching into groundwater that extends in radioactive plumes for miles from the contaminated site. Florida State University (FSU; Tallahassee) associate professor Joel Kostka and his FSU oceanography department team, during the course of a 5-year study funded by the U.S. Department of Energy (DOE), will test a natural method called bioremediation at the Oak Ridge site, according to an FSU news release.

Bioremediation involves the stimulation of naturally occurring microbes, which Kostka calls “hidden heroes,” to promote bacterial growth in the soil subsurface that scrubs it of potentially deadly radioactive metal.

If bioremediation proves successful on uranium, technetium, and nitrate at the Oak Ridge site, the process should help mitigate contamination at more than 7000 other sites nationwide — and, according to FSU, it will do so more economically and effectively than most conventional methods.

“The stakes are high and the impact potentially huge,” Kostka said. Together, those 7000 U.S. sites encompass an estimated 6.4 billion m3 (1.7 trillion gal) of contaminated water — about four times the nation’s daily water consumption — and about 41 billion m3 (11 trillion gal) of contaminated soil.

Kostka has a 5-year, $1 million share of the total $15 million in DOE funding for the project. With research teams from FSU as well as the lead institution on the project — the Oak Ridge National Laboratory — the project partners will develop models to help predict the rate at which contamination levels drop when using both bioremediation and artificial techniques, such as chemical additions and pH adjustments. Subsurface changes are monitored using geophysical methods that send acoustic, electric, and other signals into the ground.

Kostka’s research team will lead the subsurface microbiology portion of the project.

“As it now stands, bioremediation, which is potentially much cheaper than current technologies, has not been used much at all, but it should be,” Kostka said. “Subsurface aquifers, where most of the radioactive contamination resides, are primary sources of groundwater used for drinking, and contaminated aquifers tend to be extreme environments where microorganisms dominate. These microbes are the ‘hidden heroes’ that do the work of bioremediation. Our new project will provide the basic science necessary to deploy bioremediation technologies at the scales necessary for them to be effective at U.S. DOE sites.”

More information on Kostka’s bioremediation research is available at www.joelkostka.net/biorem.cfm.