October 2001

From Virginia Tech

Humboldt awarded for study of acid-mine drainage in Germany

Blacksburg, Va., — Michael F. Hochella Jr., professor of geochemistry and mineralogy at Virginia Tech, has received the prestigious Humboldt Research Award to work in Germany on acid-mine drainage.

"Acid-mine drainage is an environmental problem of vast proportion," said Hochella, professor of geological sciences. In a 1998 collaboration when Hochella was a Fulbright Senior Scholar, he and Andrew Putnis from Universität Münster gained a detailed understanding — the first time this had been done — of the way toxic metals can be transported so far from the mining sites, sometimes hundreds of kilometers.

They also studied where acid-mine drainage originates and is most acute. With the Humboldt award, the two researchers will continue the most critical phase of this work by collecting and interpreting data from drainages coming from two major acid-mine drainage sites, one in Germany and one in the United States.

"Mineral-water interfacial interactions associated with working and abandoned sulfide-bearing mines and mining wastes are among the most complex, dynamic, and environmentally important of all near-surface rock-water systems," according to Hochella.

"These mining sites, numbering more than 200,000 in the United States and Germany alone, typically release large amounts of metals into the environment, ranging up to hundreds of kilometers along hydrologic gradients in a relatively short time. Contamination occurs when high solute concentrations of iron and other more toxic metals form during the weathering of pyrite and associated metal sulfides. These acidic effluent flows, from mine entrances and waste piles, mix with air and oxygenated surface water and precipitate metal oxides, oxyhydroxides, and/or hydroxysulfates."

These phases form mineral/rock coatings and sediments down to the nanometer scale that may contain very high concentrations of contaminating metals—up to percent levels of, for example, copper, zinc, and lead—and can be transported long distances. Hochella and Putnis first described these associated phenomena after finding an effective way to collect and prepare critical samples from natural environments.

For the study using the Humboldt award, the researchers will use two sets, or suites, of samples from acid-mine drainage sites. The first is in the vicinity of Narz-Gebirge on the border of the former East and West Germany, and the second is near Butte-Anaconda in Western Montana.

"Both of these sites are world-class acid-mine drainage sites in terms of size and environmental importance," Hochella said. The instruments the scientists will use to analyze the samples are at the Institüt für Mineralogie and Interdisciplinary Center for Electron Microscopy and Microanalysis at the Universität Münster.

Hochella and Putnis hope their work will enable them to develop better models of metal transport. Subsurface and surface-water reactive transport models that attempt to describe the distribution of toxic metals away from contaminant sources have been generated over the years, Hochella said. "However," he said, "these models cannot describe systems far from equilibrium nor systems where greatly varying microenvironments dominate. In this study, by identifying toxic-metal-bearing phases and determining their distribution in the drainage system using the equipment in Germany, and combining this information with thermodynamic considerations, it will be possible to develop much more robust metal-transportation models than currently exist."

Hochella also leads a project that was recently awarded a $1-million award from the National Science Foundation’s newest initiative, Nanoscale Science and Engineering. The project is entitled "Nanoscale Processes in the Environment: Nanobiogeochemistry of Microbe/Mineral Interactions."

Team members include Susan Eriksson, Madeline Schreiber, and Chris Tadanier, all from Virginia Tech’s Department of Geological Sciences, as well as Steven Lower at the University of Maryland.

PR CONTACT: Sally Harris 540-231-6759, slharris@vt.edu Learn more about Dr. Hochella's work at http://www.geol.vt.edu/profs/mfh/mfh-r.html

Learn more about Dr. Putris work at http://www.uni-muenster.de/Mineralogie/individuelle%20Forschungsvorhaben/putnisresearch-e.html. Reach him at:

Prof. Dr. Andrew Putnis
Institut fur Mineralogie
Universitat Münster
Corrensstrasse 24
D-48149 Münster
Tel: 0251-833-3451
E-Mail: putnis@nwz.uni-muenster.de











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