May 5, 2010
Media contact: Anne Russell
Cell: 604-798-3709
Office: 604-795-2826
anne.russell@ufv.ca
UFV’s Justine Cullen wins international
geology student award
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Justine Cullen and Dr. Olav Lian |
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A student who works at a university near the heart of the west coast rainforest has won a prestigious international geology award for studies related to desert environments.
Justine Cullen is a third-year BSc Honours geography student at the University of the Fraser Valley who is working in Dr. Olav Lian’s Luminescence Dating Laboratory, where she often works in total darkness, analyzing tiny grains of sand at the atomic level. She was recently notified that she has won the Geological Society of America’s 2010 Farouk El-Baz student award.
Students from all over the world compete for this award, and only two are given each year, usually to a student at the master’s or doctoral level. Cullen is the first undergraduate student to ever receive the award, and one of only two Canadians. The award is named for Dr. Farouk El-Baz, a veteran of NASA’s Apollo program, who is renowned for pioneering research in the applications of satellite images to study deserts.
The award is for students conducting fundamental research in desert and dryland environments, and Justine’s application was based on her proposed honours research in the Luminescence Dating Laboratory. Her research will focus on developing dating protocols for sand dunes in the Canadian prairies that serve as indicators of long-term climate change.
Cullen, who hails from Mission and graduated from Hatzic Secondary, has caught the research bug since enrolling at UFV. She initially wanted to become a high school teacher, but now plans to pursue graduate studies in the field of geology.
“Once I learned more about the opportunities available to me by working in the lab, I got excited about the prospect of research, travel, and a variety of career options,” she says.
UFV is home to one of the few luminescence dating laboratories in North America, and the only Canadian laboratory of its kind west of Ontario. Lian says that his lab’s research is of great interest to climate scientists.
“They are very interested in knowing when the sand dunes in the prairies were last active,” he notes. “We are attempting to perfect a method of getting the precise age of the sand dunes by analyzing long-buried grains of sand and isolating and studying electrons trapped within them. The light given off by the trapped electrons when they are stimulated in the laboratory gives us clues about the timing of dune activity.”
The UFV researchers have used their luminescence dating techniques successfully at other sites. The site that Cullen plans to study further as part of her BSc Honours thesis project is proving more challenging, in that these sand dunes contain charcoal and tephra (volcanic ash) beds that have defined independent ages. But the luminescence dating results are showing a younger age result than the other independent dating techniques.
“We need to better understand and account for this age-reporting variance before the method can be applied more widely in the region. To be able to obtain accurate age results using our luminescence dating techniques, we need to perform a series of laboratory experiments to determine the best protocol for working with quartz sediment particular to the region,” Cullen says.
Cullen will travel to the Geological Society of America Annual meeting ― where thousands of earth scientists from all over the world gather to discuss their research ― in Denver, Colorado, next fall to receive her award, which will amount to approximately $2,500 in addition to the prestige that comes with it.
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More about the UFV Luminescence Dating Laboratory
Dr. Olav Lian and his students specialize in exploring how the earth’s surface has changed over time by analyzing long-buried grains of sand.
“By examining grains of sand at the atomic level, and the character of the sedimentary landforms in which they are found, we can find out more about environmental change over long periods of time,” says Lian.
“Studying landforms is one of the best ways to find out what has happened at the surface of our earth in the past. We now know that there have been several periods of abrupt climate change since the last ice age ended.”
Doing so involves adventurous forays out into the field to collect samples, but also long hours in the near-total darkness of UFV’s Luminescence Dating Laboratory, as they prepare granular sand specimens for analysis, and run the data through analytical software.
In essence, the process is about finding and counting tiny electrons that have become trapped in structural defects and impurities that occur within quartz grains (or other minerals). These electrons have become freed from their normal places in atoms by exposure to naturally occurring radiation in the environment.
The researchers do this by isolating quartz grains from the bulk sediment sample collected from the landform of interest. The process involves adding acids and other chemicals to the bulk sample to get rid of unwanted minerals and organic material. The separated quartz grains, each no more than a fraction of a millimetre across, are then mounted onto the surface of tiny aluminum disks, which are in turn placed in a carousel within an instrument.
“We can’t see the electrons, but we can make them give their identity up by forcing them out of where they are trapped,” explains Lian. A computer instructs the instrument to turn the carousel to a position within the instrument where intense blue-green light of a specific wavelength is shone on the quartz grains. The blue-green light serves to stimulate or “jiggle” the electrons out of their traps. The freed electrons promptly find themselves at another kind of site in the quartz grain where excess energy is given off as light of a different colour, ultraviolet in this case. It is this light which is the luminescence that is measured.
“Simply put, the brighter the measured luminescence, the more time has passed since the quartz grains were last exposed to sunlight, and the older the landform from which the grains were collected,” explains Lian.
The instrument is also used to determine exactly how the brightness of the luminescence measured from the sand grains increases with burial time.
“We want to know whether leaving the sand grains buried in a sand dune, for example, for twice as long doubles the intensity of the luminescence measured, or whether the response is more complicated than that,” notes Lian. “To determine this, the instrument turns the carousel so that the disk holding the quartz grains is under a radioactive source (strontium-90). The grains are exposed to the radiation, and then the luminescence is measured as before; this is done for various doses of radiation. Exposing the sand grains to radiation in the instrument essentially makes them ‘older’, thus simulating a long burial time.”
The laboratory’s equipment needs to measure the extremely low intensities of light that the quartz grains emit when the electrons trapped within them are stimulated, without getting overwhelmed by normal room light. Moreover, exposing the quartz grains to normal room light would empty the electron traps before they can be measured. That’s why the laboratory’s rooms must remain in almost total darkness when the experiments are in progress. Entering the laboratory is like going into Batman’s cave, with a special portal door that prevents external light from shining in. Lian and his student assistants live a bit of a mole’s life, working with only very low-emission lights in their darkened environment.
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