The Amazing Isotope Machine
It can analyze your fingernail clippings to tell how high in the food chain you eat, or identify the migration path of a butterfly. You might call it (drum roll, please), The Amazing Isotope Machine.
One of the treasures of the Science Center is a piece of equipment about the size of a small refrigerator. Called an isotope ratio mass spectrometer (IRMS), this sophisticated instrument has placed Keene State College in the forefront of scientific research in northern New England, attracting graduate students from regional universities and enabling Keene State undergrads to ask – and answer – complex questions in areas ranging from biology, geology, and environmental studies to forensics and anthropology.
The IRMS was purchased in 2002 after professors Renate Gebauer, Tim Allen, and Steven Bill received a $90,000 matching grant from the National Science Foundation, the first grant ever awarded a public college for this piece of equipment. The instrument was initially installed in a tiny closet in the old science building; once the new Science Center opened last fall, its full capabilities could be explored.
The principle at work is that stable isotopes (elements identical in atomic number but different in mass) of carbon, nitrogen, oxygen, and hydrogen are natural storytellers. They act as tracers, enabling scientists to differentiate between, for example, a water molecule from ground water and one from rainwater. A plant might take up both molecules, but a biologist with access to an IRMS can analyze the stable isotopes in the plant to tell how much of each water source the plant uses.
In a recent interview with Professor Gebauer, she described some of the work KSC students can do with the help of the IRMS, a real-world Wizard of Oz that reveals the answers without the smoke and mirrors.
1. KSC students are working with the National Park Service to determine why some streams in the Santa Monica Mountains in California now run year-round, enabling invasive species to thrive along the riparian corridor. (Hint: run-off water from lawn sprinklers and leaky pipes has a different isotopic signature than rain- or groundwater.)
2. Is your maple syrup from Vermont or New Hampshire? More importantly, is it adulterated with corn syrup? The IRMS knows a Vermont sugar maple when it sees it. Best of all, it can detect corn syrup’s heavy carbon isotope 13C in a flash.
3. Is your expensive bottle of ice wine really made the traditional way, or did someone just add cheap sugar to cheap wine? Again, the IRMS knows its sugars by the carbon isotopes.
4. Anthropologists asked, When did corn become an important part of the diet of Native Americans in the Desert Southwest? They analyzed carbon isotopes in the skeletons and found that corn wasn’t introduced to North America until about A.D. 500; by A.D. 1200, Native Americans relied on corn for 60 percent of their diet.
5. Are you a vegan, a vegetarian, or on the Atkins diet? The IRMS knows the answer through your fingernail clippings. The higher you eat on the food chain, the more of the heavier nitrogen isotopes (15N) you accumulate.
6. Where do migratory birds spend the winter? Biologists use the IRMS to analyze a feather for hydrogen, carbon, and nitrogen isotopes to figure out where the bird was when the feather was growing. The analysis of wings of monarch butterflies in other laboratories has shown that most monarchs overwintering in Mexico are from the Midwest, and their decline is likely due to pesticide use.
7. How unusual are our global temperature fluctuations compared to those of the past? To answer this, climatologists took core samples in Greenland and analyzed the air bubbles trapped in the ice. The IRMS measured carbon and oxygen isotopes in the CO2 to determine temperatures thousands of years in the past.
8. Anti-terrorism investigators can use the IRMS to track down the source of explosives; those engaged in stopping drug trafficking can determine the geographic source of heroin and cocaine with the IRMS and target their efforts.
9. What decomposes faster, an orange peel or a banana skin? KSC biology students analyzed the process of decomposition by tracking nitrogen isotopes: the more decomposed a substance, the richer it is in 15N.
10. Can you tell an organic cow from a conventional cow? Professor Sally Jean’s chemistry students can. The 13C in the bones reflected different cattle feeds.
These projects are just the start, as Keene State undergraduates take advantage of a rare opportunity to use state-of-the-art technology to explore the natural world.