Atmospheric Chemist: Kristie Boering

Awareness of atmospheric chemistry has grown with the tremendous publicity surrounding such important phenomena as the ozone hole and global warming. Assistant Professor Kristie Boering recently received a coveted Packard Foundation Fellowship to study atmospheric processes on different temporal and spatial scales.

Q: What attracted you to atmospheric chemistry?
KB: My background is in physical chemistry, and the photochemical isotope effects that occur in the stratosphere (the upper part of the atmosphere that extends from seven miles to thirty-one miles above the earth's surface) are very interesting. They represent a new class of isotope effects arising from subtleties in reaction dynamics. Yet physical chemists did not study them until these dramatic differences in reaction rates for different isotopic species were discovered by scientists making measurements in the stratosphere, rather than in the laboratory. Thus we are discovering new microscopic phenomena in the atmosphere and then testing how these molecular scale details integrate back onto a global scale.

Q: How is the publicity surrounding some of the big issues in environmental chemistry affecting the students who enter graduate school?
KB: We've seen the number of graduate students interested in atmospheric chemistry increase dramatically in the last few years. This year eight incoming graduate students (out of eighty) indicated an interest in and are working in atmospheric chemistry labs­the most ever for one year. The environment is of great concern to the younger generation, and they feel that if they can get a Berkeley Ph.D., they can become world-class scientists and apply their knowledge and skills to an environmental problem.

Q: How do you perform your research?
KB: My research breaks traditional disciplinary boundaries by focusing on the molecular-level details of atmospheric processes, global atmospheric composition, and biosphere-atmosphere coupling. We measure the isotopic composition of trace gases in the stratosphere on air collected from high-altitude aircraft and balloon instruments, perform laboratory experiments to isolate and study the fractionation step, and use computer models of the atmosphere to determine whether the molecular level details from the lab experiments can be extrapolated to the globe. For example, my recent work showed that the unusual isotopic signature created in O3 when O3 is formed is transferred to CO2 and O2, molecular species that act as chemical "integrators". O3 is short-lived but CO2 and O2 are not, hence integrated ozone production rates can be derived from our observations of stratospheric CO2. Furthermore, information on rates of carbon fixation by the biosphere (which produces isotopically normal O2 and destroys the isotopic signature created in the stratosphere) can be obtained through isotopic measurements of O2 in today's atmosphere and back in time through measurements on gases trapped in bubbles in ice from Greenland and Antarctica-a record that goes back 400,000 years!

The new information obtained from CO2 and O2 will help us make significant steps forward in quantifying details of ozone depletion over the last twenty years and in understanding the response of the biosphere to global environmental change.

Q: What do you hope to accomplish as a scientist?
KB: I am particularly interested in the relationships and feedbacks between atmospheric chemistry and composition and climate changes-both over time and as a means of making sound predictions for the future. One of the biggest challenges facing atmospheric chemists today is whether we can accurately define the feedbacks between the biosphere, geosphere, and atmosphere as well as transformations that happen solely within the atmosphere as the Earth is subjected to both natural and human-induced perturbations. It could turn out that a very minor chemical reaction under the present conditions could become very important as climate changes.

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