April 17, 2008
Media contact: Anne Russell
Cell: 604-798-3709
Office: 604-795-2826
or 604-504-7441, local 2826
anne.russell@ucfv.ca
A grain of sand reveals a lot to UFV earth scientists
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| Winter Moon (left) and Dr. Olav LIan in the Luminescence Dating Laboratory. |
The poet William Blake mused about seeing all the world in a grain of sand. For University of the Fraser Valley geography professor
Dr. Olav Lian and his student research assistants, it’s more a case of seeing how the world has changed over time by analyzing long-buried grains of sand. And for graduating geography student
Winter Moon, it’s also a case of how analyzing sand grains can lead to a scientific career.
As geologists, Dr. Lian and his associates view time very differently than many of us, studying climate as it has changed over the millennia since the last ice age ended more than 12,000 years ago.
“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 climate 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.”
“And we can use these data to predict what might happen in the future,” adds Moon.
Working together with their paleoecologist colleagues, who study ancient plant material preserved in landforms in order to reconstruct past environments, the researchers can find out what climate was like in the past, and when major changes have occurred.
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, process them, and run the data through analytical software.
Lian, who was a faculty member and director of a luminescence dating facility at University of London (UK), established the luminescence dating laboratory at UFV when he returned to British Columbia in 2005 to join the geography department. Trained as a physicist, Lian was a protégé of Simon Fraser University physics professor David Huntley, who, 25 years ago, invented a new method of counting electrons trapped within grains of sand in order to determine their age (the amount of time that had passed since the sand grains were last exposed to sunlight).
Now 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. The highly specialized instrument used to measure the trapped electrons is made by Risø National Laboratory in Denmark, and is called a Risø TL/OSL DA-20 system. The instrument was purchased through a generous research grant from the National Science and Engineering Research Council of Canada (NSERC). It is of similar design to the prototype invented by Huntley, and it took one year to assemble the instrument in Denmark. In November 2007, Danish technicians traveled to UCFV to set it up and test it.
“If you want to do this kind of research in western Canada, you have to come here,” notes Lian.
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 millimeter across, are then mounted onto the surface of tiny aluminum disks, which are in turn placed in a carousel within the 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.
This is where Winter Moon of Mission wants to spend much of her time for the next two years as she starts work on her master’s degree.
Moon is graduating from UFV with her bachelor’s degree in honours geography this June, and has made UCFV history by successfully applying for graduate earth science studies at Simon Fraser University, with the stipulation that the majority of her laboratory research will be conducted in the Luminescence Dating Laboratory at UCFV. Thus she will be a master’s degree student conducting scientific research at UCFV, a primarily undergraduate institution.
Not only was Moon successful in her application for graduate studies at SFU, she has been awarded a prestigious Alexander Graham Bell Canada Graduate Scholarship. This scholarship is reserved for the highest-ranked applicants to the postgraduate scholarship program administered by the National Science and Engineering Research Council of Canada (NSERC). She will receive $17,500 toward her studies. She is the first UCFV student to win the prestigious Alexander Graham Bell Canada Graduate Scholarship, and is among only four UCFV students to win an NSERC postgraduate scholarship.
As her mentor, Dr. Lian is delighted on many levels with one of his students earning such a prestigious research award.
“When applying for these sorts of highly competitive national awards, students commonly state in their application that if considered for the award they will join a major research group at one of the big Canadian research universities. What makes Winter’s application rather unique is that she stated explicitly in her application that, although she would be based in the Earth Sciences Department at Simon Fraser, she would return to the UCFV Luminescence Dating Laboratory for her research,” Lian says. “The fact that the NSERC awards panel agreed that this was a good strategy, worthy of funding with a significant graduate scholarship, gives further credibility to the strength of UCFV’s Geography Department and also gives strong evidence of the increasing recognition of UCFV by major scientific research funding agencies.”
Moon will return next academic year to UCFV as a graduate student and also serve as colleague-mentor for senior UCFV science students being taught in the Luminescence Dating Laboratory.
“Winter’s example will demonstrate to current UCFV students just what can be done with a UCFV degree,” says Lian.
Moon, a graduate of Mission Senior Secondary, was unsure of what career to pursue until she tried a physical geography course and was hooked by the combination of field work and laboratory work.
“I find Earth processes really interesting,” she says. “I like to go out in the field and collect data, and see how things manifest once we analyze them.”
UCFV recently added a Bachelor of Science (BSc) degree in physical geography to its offerings, complementing the Bachelor of Arts (major and honours) degree in geography; a BSc honours degree in physical geography is soon to follow. To find out more about geography studies at UCFV, go to www.ucfv.ca/geography.
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