CHESS lecture series is launched with a discussion of toxic pollution

By Larry Klaes

Since the late 1970s, the Cornell High Energy Synchrotron Source (CHESS) has been a National Science Foundation facility that uses the X-rays produced by the Wilson Laboratory particle accelerator for interdisciplinary studies in all fields of science. Over the past five years, more than 50 Cornell faculty members have used CHESS in their research efforts, and well over 150 Cornell doctoral degrees have resulted.

But CHESS Director Sol Gruner and Assistant Director Ernie Fontes want more people to know about more far-reaching and high-impact applications of X-rays.

The result: CHESS, with support from Provost Biddy Martin, has created a Frontier Applications in Synchrotron Radiation Lecture Series to highlight pioneering scientists who are using X-rays in areas ranging from biology to the environment.

Brown

The first lecturer in this new series is Gordon E. Brown Jr., the Kirby Professor of Earth Sciences and professor and chair of the Stanford University Synchrotron Radiation Laboratory. He is presenting three lectures this week; two have already been given, with the third and final lecture scheduled for noon today in G10 Biotechnology Building.

"Gordon Brown is a terrific scientist and world leader in environmental applications of X-ray techniques," said Fontes.

Brown was the lead author of a landmark Department of Energy 2003 report that assessed the accomplishments and needs of synchrotron radiation facilities across the nation. Fontes and William Bassett, now Cornell professor emeritus of earth and atmospheric sciences, were co-authors of the report.

In his first lecture, "From Subduction to Mercury in Tuna: Hg Mining and Contamination in the California Coast Range, U.S.A.," Nov. 30 in Snee Hall, Brown explored mercury contamination in California resulting from a legacy of extensive gold mining.

Eager for every available bit of the precious metal, miners used liquid mercury to extract gold from the Sierra Nevada region from 1850 to 1981. The mercury combined with gold particles so that the amalgamated pieces could be heated to remove the gold. The resulting mercury vapor created by this process from over 2,000 mines in California found its way into the air, water and soil across the state as well as into San Francisco Bay, contaminating aquatic life.

In certain forms, mercury can be a toxin affecting the nervous system, causing everything from tremors to death. The Environmental Protection Agency says that no more than one part per billion (ppb) of mercury is the acceptable level of safe ingestion of the element by humans. In contrast, one study has found that a typical can of albacore (white) tuna contains 250 ppb of mercury, and swordfish can have up to 950 ppb. As one example, said Brown, such amounts could cause harm to the developing fetal nervous system.

Since the combining of mercury with other elements in the environment can create certain molecules that are more or less harmful than others, it is important to know exactly what kind of contaminants are present in the environment, noted Brown.

"The key to understanding the environmental impact of mercury is in understanding molecular level of speciation, or its chemical form," said Brown, who uses X-ray absorption spectroscopy to determine the types of molecules found in contaminated regions.

The Stanford professor's second lecture, "Interfaces, Heavy Metals, Microbes and Plants: Shedding New Light on Environmental Science at the Molecular Level," was presented Dec. 1 in Riley-Robb Hall. Brown examined specific case studies of environmental contamination, such as zinc in the soils of northern France, chromium and uranium contamination from the nuclear facilities at Hanford, Wash., and arsenic in Bangladesh. He explored the role of synchrotron radiation-based methods to identify these problems.

Brown's third and final lecture, "Applications of Hard and Soft X-ray Spectroscopy, Scattering and Imaging Methods to Model Environmental Systems: A Reductionist Approach to Complex Environmental Processes," will be given today, Dec. 2, at noon in G10 Biotechnology Building. The campus community is invited to attend.

The lecture will focus on recent applications of various synchrotron radiation methods to complex environmental materials and processes.

Details of the lecture series are at http://www.chess.cornell.edu/lectures.