Mary Neu is intrigued by actinides

"It is human nature to believe that the phenomena we know are the only ones that exist, and whenever some chance discovery extends the limits of our knowledge, we are filled with amazement," Marie Curie wrote when she pondered the lack of knowledge about radioactivity in Century Magazine, January 1904. "We cannot become accustomed to the idea that we live in a world that is revealed to us only in a restricted portion of its manifestations Š how numerous and varied may be the phenomena which we pass without a suspicion of their existence until the day when a fortunate hazard reveals them."

It was this intrigue that interested Mary Neu in actinide chemistry as a graduate student and later prompted her to come to Los Alamos. "Actinide chemistry," Neu says, "is very complicated and underexplored. There is much room for many important discoveries."

Neu performed her undergraduate work at the University of Alaska at Fairbanks, starting out as a geology major. She soon discovered that other physical sciences were also interesting to her and switched her major to inorganic chemistry and mathematics.

She completed her doctorate at the University of California-Berkeley with her dissertation, "Coordination Chemistry of Two Heavy Metals: Ligand Preferences in Lead Complexation, Toward the Development of Therapeutic Agents for Lead Poisoning; Plutonium Solubility and Speciation in the Environment."

Working on her doctorate, Neu conducted a wide range of synthetic inorganic chemistry and solution thermodynamic studies.

She conducted the lead chemistry on the UC Berkeley campus under the direction of Professor Ken Raymond and did plutonium chemistry at Lawrence Berkley and Lawrence Livermore National Laboratories under the direction of Professor Darleane Hoffman and in collaboration with Bob Silva, Heino Nitsche, and Richard Russo.

She completed her doctorate at the first Glenn Seaborg Institute established at Livermore in the early 1990s.

As a UC President's postdoctoral fellow, she came to Los Alamos in 1993 and worked with Dave Clark in a group that was then in the Inorganic and Nuclear Chemistry (INC) Division. Her early research here was on the synthesis and characterization of actinide carbonate species. Neu studied the processes and means that actinides form chemical bonds with other molecules.

Currently, Neu is deputy group leader of the Actinide, Catalysis, and Separations Chemistry Group (C-SIC) and is conducting research in three general areas. In the first research area, fundamental coordination chemistry, Neu is studying ligand preferences of actinides in different oxidation states and the resulting geometries of actinide compounds that may be used in new separations and processing technologies.

A second area of research is environmental speciation and behavior-studying and predicting the nature of contaminant plutonium. Neu's research, performed in collaboration with several colleagues at Los Alamos, helped identify the common oxide of plutonium(IV) as the chemical species that is prevalent in soils at Rocky Flats.

To determine how important and stable particular species are, Neu studies the formation and thermodynamics of plutonium complexes of carbonate, hydroxide, chloride, and other ligands under environmental conditions. These studies, together with actinide-mineral interactions and geochemical calculations, support the development of predictive contaminant mobility models and new cleanup technologies.

Neu's third area of research is actinide interactions with microorganisms and microbial chelators‹with the goal of using those microorganisms to stabilize or otherwise transform plutonium. For these research projects Neu works in close collaboration with colleagues in the Biosciences (B) Division, primarily Larry Hersman.

Her most exciting recent research results involve the reduction of plutonium(VI) and (V) by a common bacteria, shewanella putrifaceans. Although the exact mechanism is not well understood, these are the first results that indicate plutonium can be reduced through bacterial respiration to less environmentally mobile forms. Neu plans to further study this relationship and will submit a paper to the journal Science. She also has applied for Laboratory Directed Research and Development funds for the project.

An outcome of this research with bacteria is that she and her team have found that the toxicity of plutonium and uranium to microorganisms is generally less than that of some of the more common hazardous metals, such as zinc, nickel, and cadmium.

Her work brought her to Los Alamos because it is one of the few places in the country where she can research what she enjoys-fundamental actinide science.

She sees real difficulties in the future of actinide research and radiochemistry because there arenąt many professors teaching these topics any more. The biggest challenge to actinide science, Neu believes, is that bureaucracy, old equipment, and aging facilities impede actinide research here as well as at other facilities.

Most of her work is done in the fifty-year-old Chemistry, Metallurgy, and Research (CMR) Building. Hope is on the horizon: A new facility is planned. Neu is enthusiastic about the CMR Replacement project and hopeful that research space will be included and improved in the new facility, which is scheduled to be built around 2010.

"There is a tremendous need for modern radiological facilities across the Department of Energy complex and especially at Los Alamos, where such facilities are essential to both our core missions and to our research excellence," Neu said.

She has a passion for actinides, and doesnąt do it any differently than she did ten years ago. "I wanted to be safe ten years ago and I want to be safe now," Neu said. "I'm optimistic about the science and the incredible information we have yet to discover, but I'm also knowledgeable of the nontechnical challenges associated with actinide research."

-Kathy DeLucas

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