Featured Student Stories

It is no secret that carbon dioxide is building up in our atmosphere, threatening our planet and environment if we do not begin to seriously reduce our carbon emissions. However, Adrianna Trusiak studies an unexpected contributor to the growing levels of carbon dioxide: arctic soil.

Adrianna Trusiak is a fifth year PhD student in Dr. Rose Cory’s lab in the Earth and Environmental Sciences Department studying chemical reactions in the soil that lead to carbon dioxide emissions. As a senior graduate student, her days now focus mostly on final analyses of her data and writing her dissertation. However, her earlier years were spent doing a lot of active research both at the bench and in the environment. Adrianna spends her summers in the field in Alaska, collecting soil and water samples from many different locations and analyzing them on site. Factors such as landscape or vegetation lead to huge variations in the soil, so she says there’s never a dull day in the field. In collaboration with Stanford, she used a brand new technique to identify iron levels in the soil and whether the iron was bound to carbon.

In soil, iron can be either reduced or oxidized. When the iron becomes oxidized, it produces reactive oxygen species. These species can oxidize the carbon in the soil, turning it into carbon dioxide that then gets into our air and environment. Work in laboratory settings has already shown that oxidized iron creates reactive oxygen species, but Adrianna’s work is the first to show that these interactions lead to carbon dioxide production in the environment. However, she says there are still a lot of questions left.

“I’m trying to understand how this reaction works, how fast it happens, how much carbon dioxide is being produced, and how much of the reactive oxygen species there is in the soil.” Since carbon dioxide is a greenhouse gas, it is critical to understand how these reactions in the soil are increasing carbon dioxide levels in the environment, but Adrianna is most interested in the chemistry of it all. Her research on arctic soil is an entirely novel discovery, and the chemical reactions that lead to this increase in carbon dioxide still remain a mystery. However, she thinks these questions will be answered in our lifetime.

Since the arctic is warming twice as quickly as the rest of the planet, many scientists realize how critical it is to understand how the changes in the arctic ecosystem may lead to increases in carbon dioxide. “It’s more than just ice melting or water levels rising - it’s all of this carbon needing to go somewhere when these chemical reactions occur.” And that rise in carbon dioxide will affect the rest of the planet as well.

Apart from her own groundbreaking and relevant research, Adrianna believes that her department is addressing all sorts of critical questions in environmental science. Part of the program’s productivity comes from the support given to graduate students - while most choose a question in which their lab is already interested, they have the creative freedom to answer them in their own ways. This supportive environment allows for more ideas to be explored, and to Adrianna, that has made all the difference in her graduate career.

Maria Alejandra Rodriguez Mustafa has always been attracted to minerals. In preschool, she would dig in the playground sand pit in search of rocks. She brought a favorite home each day to show her mother: “Look, Mom, I found a new rock!” Her mother would teasingly reply that it was the same as the one she brought home yesterday. To Maria they were all different. She took note of different speckles in the rocks as she grouped them by patterns. She later advanced to using a guide to identify the minerals in the rocks she found. When enrolling in college, a geology major was an easy choice for Maria as it offered an opportunity to explore her interest in minerals and conduct exciting field research.

As a Ph.D. student in the Earth and Environmental Sciences Department, Maria now focuses on Economic Geology - a subdiscipline that seeks to understand how minerals accumulate in the Earth’s crust to optimize mining practices. She uses geochemical analysis to study magnetite, an iron oxide mineral, from iron ore deposits near Copiapó, Chile. Rock cores about 2-3 inches in diameter that can be more than 1 kilometer long are collected from Chilean iron ore mines. Maria selects small samples from those cores, each weighing about a pound. She cuts, crushes, and picks specific parts from the rock sample. She then polishes those selected fragments for a slide mount and places the mount under an electron beam. The beam hits a point on the sample that is only one to two microns wide and outputs the chemical composition of the magnetite. She uses the measured ratios of trace elements alongside iron and oxygen isotopes to fingerprint each sample in order to understand where the metals and the fluids that transported those metals came from in the Earth’s profile (i.e. shallow in the crust or deep in the mantle). “It’s like if you had an old soup in a pot,” Maria describes. “These analyses would help you figure out if the potatoes in the soup are from Michigan or elsewhere or if you used milk or water.”

Maria enjoys understanding how things formed whether it’s an iron ore deposit or a petroleum system. She’s driven by curiosity to discover and understand the big picture processes taking place in the Earth. Understanding how deposits form will help to improve exploration techniques the mining industry uses today. As the Earth’s population grows, the demand for minerals continues to grow as well. We need to efficiently find new deposits and conduct mining operations in a sustainable way to meet the growing demand. Maria compares searching for mineral deposits to finding a needle in a haystack. “Except there are no more needles on the surface, they’re all buried deep.” Exploration is progressively more difficult, so we must find more sophisticated ways to search for deposits.

“Understanding the processes that form mineral deposits is like finding your grandma’s cookie recipe,” Maria describes. “If you have the recipe, you can make grandma’s cookies in any kitchen with the proper ingredients.” Similarly, if we have the recipe for iron ore deposits, we can find them in areas we have never explored before. Maria’s research will contribute to the effort to responsibly supply minerals to the world for generations to come.