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Chasing the plume

Civil and environmental engineering "TREX" course allows students to examine firsthand the effects of volcanic emissions on air and soil quality.
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TREX 2015 students and leaders
TREX 2015 students and leaders
Photo courtesy of the 2015 TREX team.

As residents of the Big Island of Hawaii feel the adverse effects from the volcanic smog, or "vog," from the Kilauea volcano, a group of civil and environmental engineering (CEE) students are working to better understand exactly how the emissions are affecting the local air quality and ecology.

On Jan. 13, a team of 22 MIT CEE undergraduates and seven advisors embarked on a two-week journey to Hawaii to analyze the effects of the vog on the local environment. The subject, 1.092 (Traveling Research Environmental Experiences, or TREX), is part of the 1-ENG core in the environmental track offered during the Independent Activities Period, followed by a second part in the spring semester. TREX provides students with dynamic and direct fieldwork experience in the study of environmental engineering, as well as exposure to in-depth analysis of data, interpretation of results, and research presentations.

“This is an exciting opportunity for our students to go out into the field, build equipment, set up a real-world experimental campaign, and take the data back to MIT to dig deep into the analysis, interpretation, and formulate engineering solutions,” says Professor Markus Buehler, CEE department head. “Our new 1-ENG undergraduate program emphasizes such hands-on experiences that connect science, engineering, and active learning in problems of societal relevance.”

The group of students, led by CEE Associate Professor Jesse Kroll, performed a variety of studies related to Kilauea’s effects on the surrounding air and soil quality. Located on the southeastern side on the Big Island, Kilauea is the most active Hawaiian shield volcano and thus a monumental source of sulfur dioxide pollution in the region.

Sulfur dioxide (SO2) is a poisonous gas that is also highly toxic to plants; therefore, the volcano can have major negative impacts on human and ecological health. In addition, SO2 will oxidize to become sulfuric acid in both the atmosphere and soil, leading to a number of different negative effects, such as acid rain and leaching of heavy metals in the soils.

“This volcano has been erupting since the 80s,” Kroll says. “But the vent close to where we were staying only opened up in 2008 and drastically increased the amount of vog that people and plants on the island get exposed to.”

For the past three trips, CEE undergraduates have traveled to the volcano to study its impact on the immediate environment. The students worked in groups to collect data on the surrounding ecosystem’s air and soil quality. Their experience included a mixture of “in-the-trenches” fieldwork, as well as opportunities to present their findings to different audiences.

In the first part of their work, the undergraduates used portable, homemade sulfur dioxide sensors to monitor the vog levels in real time and create high-resolution pollution maps. They also scattered sensors at multiple locations at different distances from the volcano to interpret the extent to which the vog can reach, and ultimately influence, different regions. “The students basically knocked on doors and asked people if they would ‘host’ a sensor for a couple weeks,” Kroll explains.

“Vog has become a significant public health concern on the Big Island,” adds co-instructor and CEE Associate Professor Colette Heald. “The kind of high-resolution pollution maps that the students produced provide exciting new insights into the variability of sulfur dioxide exposure, and the power of small sensor technologies for understanding our environment.”

For the study of the chemical analyses of the air, the students joined forces with University of Toronto Professor Jennifer Murphy and utilized more advanced instruments at a fixed site downwind of the volcano. These were installed within a Hawaii Department of Health air quality monitoring station in order to determine how the particle chemical composition of the volcanic smog changes during its time in the atmosphere.

The third part of the project, under the guidance of TREX co-instructor and CEE Assistant Professor Benjamin Kocar, centered on the examination of soil quality as a function of distance away from the volcano. After choosing a selection of spots downwind of the crater, students collected soil samples and analyzed their properties, including acidity, sulfur, and ammonia levels, as well as aluminum concentration.

One of the more surprising elements found in the soil, says Kocar, was the high level of fluorine — a measurable consequence of the vog that is directly responsible for the notable surge of fluorosis in the population’s livestock.

While the poor air quality surrounding the volcano has been noted in the past, Kocar says the effects on the soil have not been examined in this particular fashion.

“What we are going to do now, in the lab at MIT, is measure the amount of fluorine in the soil samples,” Kocar explains. “ Is fluorine making its way into the food chain from the vog? This is the question we haven’t answered yet, but we will this semester.”

In conjunction with their hands-on research, the students had two opportunities to orally present their findings: once to the scientists at the U.S. Geological Survey’s Hawaiian Volcano Observatory as well as in a public talk, sponsored by the University of Hawaii, that was attended by approximately 60 members of the community.

Approximately half of the TREX students will participate throughout the spring semester in the analysis of the collected data. Using their field measurements, they will continue to explore the air quality and ecological impacts of Kilauea on the local environment and gain a fuller exposure to the scientific process.

“The main goal of this [program] is to give students experience in environmental fieldwork,” Kroll says. “Going out into the field is a central part in the study of environmental science and engineering, and the fact that students get to take part in a full-on field study, involving important questions and state-of-the-art techniques, is something that I think is very special about our department.”

According to Kocar, the opportunity for students to experience “real-world research” in all of its imperfections is the most fascinating piece of the TREX process. To think in the field, compile a set of results, and try to find the right answer is an essential challenge for the students, he says.

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