April 2002
Patenting Human Genes

Putting it All Together

Measuring Cosmic X-ray Fireworks

Understanding Gene Functions Through Mutation

New Fellowships Integrate Teaching and Research

Pursuing Answers to Big Questions

Commentary: The Mentoring Mindset

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Al Dorof, Editor

© 2003


Bryn Mawr College
A quarterly newsletter on research, teaching, management, policy making and leadership in Science and Technology

(left to right)
John Freeman
Jill Dill Pasteris ’74
Brigitte Wopenka

Pulling It All Together
by Dorothy Wright

When Jill Dill Pasteris ’74 studies a rock or mineral, she is reading the synopsis of a complex story that pulls together elements from biology, chemistry, physics and mathematics. A professor of earth and planetary sciences at Washington University in St. Louis, Pasteris explains, "An incredible sense of time and cycles is captured by rocks. The study of earth science is a powerful way to bring together what otherwise might have seemed disjointed facts."

It is a lesson she learned well from her geology teachers at Bryn Mawr. "Professor Weecha Crawford was great at conveying that lesson," Pasteris recalls. "We’d be studying factual information, and then on a homework assignment or exam, she’d pose a question that would ask us to pull it all together.

"This pulling process could be painful," Pasteris says, laughing, "But I have realized that there is a higher-order understanding in addition to all the factual information. For me that’s really the power of science."

Over the years, Pasteris’ interest in discovering how things come together has led her to cross the boundaries between the sciences. An economic geologist (one who studies ore deposits), Pasteris takes a mineralogic-geologic approach to studying both traditional and nontraditional materials — from fluid inclusions in minerals and glasses to nanocrystalline precipitates and biological minerals in bacteria and humans.

Pebbles in Her Pockets

Pasteris was captivated by earth science at an early age. "I was always fascinated with rocks," she recalls. "My mother would complain that when she’d go to throw my clothes in the washer, the pockets would be full of pebbles."

Her ninth-grade geology class intensified her interest. "We went on a field trip to a boulder field," Pasteris says. "I was so excited! It was just amazing to find all these rocks wherever I looked!" She says her family knew she would become a geologist even before she announced her intentions one day. "They said, ‘Sure, what else would you be?’"

When Pasteris was searching for a college, she discovered Bryn Mawr. "That was the place for me," she says. "Of course I knew I wanted to be a geology major and ended up taking a huge number of courses. Professors Weecha and Bill Crawford were my mentors, and all of my professors were great."

Pasteris recalls taking an introductory geology class with Edward Watson. "He was from the old school," she says. "He would come in to lecture with his suit on underneath his white lab coat — the quintessential scientist. He had marvelous stories to tell about his experiences as an expert witness on quarrying."

For her senior project, Pasteris studied the formation of very old marbles — which are calcium carbonate rocks — collected from local outcrops. "The other day I opened an old book and out popped a letter from Weecha Crawford identifying me as a Bryn Mawr geology student. I carried it around in the field so that when I knocked on people’s doors to ask if I could walk across their fields to look for marble outcrops, they wouldn’t think I was loony!"

A Bold Idea

A 1974 Fulbright Scholarship took Pasteris to the University of Heidelberg, Germany, where she studied ore-deposit rocks. The next year she began her Ph.D. work at Yale. "I became intrigued with the tiny inclusions of fluid within minerals. That was not part of my thesis, but I kept it in the back of my mind."

After completing her doctoral degree at Yale in 1980, Pasteris joined the faculty of Washington University, where she pursued the study of fluid inclusions. "Some of the most important past and ongoing geologic processes are chemical reactions among melts, aqueous fluids and rocks," she explains. "One key to the nature of the fluids involved in these processes is the composition and density of minute fluid inclusions that are trapped within minerals.

"I talked with Weecha and she told me about a new technique that the French were beginning to use to study these fluid inclusions: laser Raman spectroscopy," Pasteris recalls. Laser Raman microprobes enable spatial imaging and spectroscopic analysis of sample areas as small as one micrometer in diameter.

"I looked into it further, and for some crazy reason — I wonder now how I could be so bold — I thought I would like to purchase one of these instruments. In this country, the technology really got going in the semiconductor industry," Pasteris explains. "But at that time, none was in use in a university geology department."

Nevertheless, Pasteris convinced the university, corporate donors and the National Science Foundation to fund her purchase of the first laser Raman microprobe for a geology department in the United States.

The Instrument Guides the Interest

After meticulously testing and validating the data generated by the instrument, Pasteris and two of her Washington University colleagues, chemists Brigitte Wopenka and John Freeman, put it to work to study natural fluid inclusions and experimental analogs.

As they learned more about the instrument’s capabilities, it began to guide their interest in new directions. For example, they used the technique to shed light on the dynamics of the 1991 eruption of Mt. Pinatubo in the Philippines. By the mid-1990s, scientists in other disciplines — from mechanical engineers to oceanographers — became interested in Pasteris’ work with the Raman microprobe.

Among the diverse studies her group has worked on are the identification of microcrystalline substances in human breast tissue adjacent to silicone implants, the effectiveness of fluoride treatments to decrease bone failure in osteoporotic patients, and the feasibility of stably incorporating greenhouse gases into solid materials — essentially, carbonated ices — for permanent storage on the sea floor.

Pasteris is sharing these new insights with her graduate and undergraduate students. In addition to teaching Earth materials, mineralogy, economic geology and Earth resources, she developed a new course in environmental mineralogy. It covers such topics such asbestos/fibrous minerals and their health effects, the mineralogy of arsenic poisoning and remediation, clathrate hydrates as sources and sinks for greenhouse gases, and materials for nuclear waste storage.

The Human Element

Pasteris contemplates the implications for human health of her group’s recent research in biomineralization and medical mineralogy. "The positive side is that we might provide additional information leading to better knowledge of how to fight a disease," she muses. "I never saw myself in a role like that before. That’s the gratifying part.

"The scary part — and I say that only half jokingly — is that if we made a mistake in a calculation or analysis on a rock sample, it wouldn’t matter to most people. Nobody’s life is hanging in the balance. We are always meticulous about our analyses, but we never before had to think about somebody’s medical treatment being based on our knowledge. That is in the back of our minds now."

Pasteris’ tone lightens perceptibly when she considers the fact that her research on storing greenhouse gases relates to carbonate rocks. One could say that she has come a long way since her Bryn Mawr days, when she collected her first marble samples. On the other hand, she says, laughing, "I’m back to carbonates, so maybe I should think about having come full circle!"

About the Author:

Dorothy Wright contributes news and feature articles on science, technology, engineering and general interest topics to a variety of publications, including Civil Engineering, Engineering News Record and Bryn Mawr Now.

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