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As a child, Pablo Pastén used to accompany his father to rivers in Chile’s Atacama Desert. His father worked for the General Directorate of Water and would wade into the waterways to measure their flow. Pastén waited for him on the riverbank.
Vitals
Hometown: Calama, Chile
Education: Civil engineer, hydraulic engineering, and MSc, civil engineering, Pontifical Catholic University of Chile, 1995; PhD, environmental engineering, Northwestern University, 2002
Current position: Principal researcher of the Healthy Watersheds project, Center for Sustainable Urban Development
Favorite molecule: H2O. Water is life.
Favorite music: Symphonic metal
Recent project: A stained-glass lamp with Charles Rennie Mackintosh designs
I am: Latino
“I would spend hours observing and asking myself questions about the rivers here in Chile,” Pastén says. “It was a very special moment.” Having grown up in Calama, a municipality deeply linked to the copper industry, he became especially interested in the waterways that flowed through mining environments.
These childhood expeditions with his father marked the start of Pastén’s journey to become a lead researcher of the Center for Sustainable Urban Development (CEDEUS) in Chile, where he uses geochemistry to address societal challenges and influence public policy. One of the main issues that Pastén is working on through CEDEUS is the environmental impact of mining, an industry that accounts for over 11% of the country’s gross domestic product, according to Statista. Tailings, or waste created after the ore is processed, often contain toxic elements, including heavy metals and other chemicals that can leach into water and soil.
According to Pastén, one of CEDEUS’s most consequential projects began when he and his team visited Copiapó, another city in the Atacama region. They were organizing a seminar when they learned that the community was concerned about some nearby tailings. Pastén remembers being struck by a photo from a journalistic investigation that showed a playground slide right next to a pile of mining waste.
The article that accompanied the photo told the story of Viñita Azul, an urban development in Copiapó that was built next to abandoned tailing ponds dating back to 1990. Construction continued despite warnings from Chile’s National Geology and Mining Service about the potential for hazardous contaminants.
Pastén wondered what would happen to his daughters if they were to play on that slide. He knew he had to do something about the situation.
He and his team analyzed samples of road dust from Copiapó with a portable X-ray fluorescence spectrometer, which could identify metals and measure their concentrations in the area. Their findings were alarming: levels of copper, lead, and zinc exceeded international guidelines for residential soil.
They published their findings in 2022, which helped revive the discussion of a soil framework law for Chile that had been inactive for years (Appl. Geochem., DOI: 10.1016/j.apgeochem.2022.105230). The impact of this work also led Pastén to write a book about public policies for sustainable urban development and discuss his pollution research with Chilean legislators.
Looking back on his time as a graduate student at Northwestern University, where he used a synchrotron to study the minerals formed by aquatic bacteria, he never thought that this introduction to the field of chemistry would lead him to inform policy on soil management in his country. In fact, he didn’t even want to be a chemist. He originally trained as a civil engineer at the Pontifical Catholic University of Chile (UC) to follow in his father’s footsteps and preserve the health of Chile’s rivers.
It’s interesting how the need to work with the community and for the community suddenly changes our lives.
Jean-François Gaillard, an environmental chemist at Northwestern University, remembers that when Pastén joined his laboratory, he was reticent about chemistry and wanted to focus on computational modeling instead.
“A lot of engineering students want to get out of chemistry because it’s too complicated. It has a bad reputation,” Gaillard says. But he managed to spark Pastén’s interest. Although Pastén was not a chemist by training, Gaillard thought he had gained the title after the hours they spent together in the lab doing research for Pastén’s PhD.
Pastén then returned to UC and became a lead researcher at CEDEUS. He also began teaching chemistry to students in the Department of Hydraulic and Environmental Engineering.
Credit: Tamara Merino
Pablo Pastén takes samples from Las Amarillas creek, which feeds into the water supply of Santiago, Chile. Long term, his lab is monitoring how climate change affects the creek.
Alejandra Soledad Vega Contreras, who took one of Pastén’s courses as an undergraduate, remembers him as a strict and demanding professor. “But he is so motivated when he teaches that I think he is one of the reasons I actually got my PhD in environmental engineering,” she says. She now works as a researcher at CEDEUS.
Pastén also taught his students how to use chemistry to address problems afflicting the people of Chile. Sara Ester Acevedo Godoy, who worked in Pastén’s lab as an undergraduate, says he has a knack for scientific outreach. In January, for example, Pastén participated in a roundtable with a senator from the National Congress of Chile to discuss ways to link science to public policy. Now, Acevedo is trying to do the same as one of the chemists working on CEDEUS’s Healthy Watersheds project, which aims to study the natural and human stressors on Chile’s urban water sources in an effort to protect them.
Beyond noting Pastén’s contributions to science, Acevedo describes him as “the axis of many stories” because of the many lives he has affected. She and Vega highlight how Pastén actively promotes gender equality in engineering research, a field they both describe as currently dominated by men. Although women make up only 30% of enrollments in UC’s School of Engineering in 2020, Vega says Pastén supervises roughly equal numbers of men and women.
“Pablo is a total siete. In Chile, when we say someone is a seven, it means he is the best,” Acevedo says.
Robert Nerenberg, an environmental engineer at the University of Notre Dame who met Pastén when they were PhD students at Northwestern, recalls the key role that he and Pastén played in an agreement between Notre Dame and UC that allows students to enroll at both universities and earn a dual degree. This university collaboration gives UC students access to lab equipment not available in Chile, like the synchrotron Pastén used as a grad student.
Pastén believes in the power of the legacy that teachers can leave their students. For him, part of his legacy is teaching applied chemistry in Chile and getting more engineers like him into the lab. “It’s been a long road since the synchrotron,” Pastén says. “It’s interesting how the need to work with the community and for the community suddenly changes our lives.”
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