Pooling Expertise to Combat Pollution

Fall 2008

Alan T. Stone and Justine  P.  Roth
Researchers Alan T. Stone and Justine P. Roth bridge the School of Engineering and the School of Arts & Sciences to jointly explore pollutant reactions.

Two Johns Hopkins chemists—one environmental and the other bioinorganic—have joined forces to create a new approach for studying pollutant reactions in the environment. By drawing on their different areas of expertise, researchers Alan T. Stone and Justine P. Roth hope to develop a better way to predict the behavior of previously unexplored pollutants, including some hazardous metals.

The Krieger School of Arts and Sciences’ Roth, an assistant professor in the Department of Chemistry, develops methods to examine how enzyme-bound metals gain or lose electrons, most notably in response to reactions with oxygen. A number of elements, including oxygen, exist as two or more natural isotopes, meaning their atoms possess the same number of protons but different numbers of neutrons. Molecules made up of different isotopes react at slightly different rates when the electrons move from one position to another. By comparing these rates, Roth is able to collect important information about the reactions and interpret the results using computational chemistry.

Stone, an environmental chemist in the Whiting School of Engineering, realized that Roth’s approach could uncover critical new data about how pollutant molecules react with chemicals that are naturally present in water, soils, and sediments.

Their decision to pool resources recently received a key endorsement from the Camille and Henry Dreyfus Foundation, which allocated a $120,000 fellowship grant that will sup- port two years of research by a postdoctoral scientist who will be supervised by both faculty members. The researcher will seek to develop fundamental models that describe the transfer of electrons to and from dissolved chemicals and mineral surfaces.

Roth and Stone are especially interested in gains or losses of electrons that occur when pollutants react with naturally occurring minerals. For example, manganese oxide minerals, which appear black, and iron oxide minerals, with red, yellow, orange and brown hues, are believed to play a particularly important role when they make contact with some hazardous metals. When these minerals take electrons away from the toxic metal chromium, the metal is less likely to stick to soils and is often carried away by water. In contrast, taking electrons away from the toxic metal lead causes the metal to precipitate, forming solid particles that separate from the water instead of dissolving in it.

The Johns Hopkins scientists say the Dreyfus Foundation funding should bolster their efforts to use advanced chemistry lab techniques to help remedy real-world concerns.

“We need a better understanding of what kind of chemical reactions occur when hazardous metals and other waste materials come in contact with minerals that are already there in the environment,” says Stone.

Adds Roth: “In the past, these types of questions haven’t been addressed because the tools weren’t available. This is a chance to apply some of our new lab techniques to practical problems encountered in the Chesapeake Bay and other ecosystems. We’re really forging a new field in environmental science by focusing on the fundamental reactions that are taking place when contaminants are present in soil and water.”