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Follow the pesticides, clean the environment

To protect human health, civil and environmental engineer Felipe de Barros tries to predict how pollutants travel in subsurface water

Felipe de Barros believes his work will provide reliable predictions of how pollutants travel in the subsurface. (Photo/courtesy of Felipe de Barros)

Felipe de Barros wants to mitigate the environmental hazards caused by chemicals leaching into the soil and reaching the water table.

Through his research, the Brazilian native and USC Viterbi School of Engineering assistant professor aims to model subsurface water flows and figure out how chemicals travel in subterranean conditions.

Felipe’s work has implications in many fields, from sustainability to human health.

Lucio Soibelman

“Water is scarce, and it is known that we can’t find a replacement for it,” said Lucio Soibelman, chair of the Sonny Astani Department of Civil and Environmental Engineering. “Felipe’s work has implications in many fields, from sustainability to human health.”

Chemical contaminants

De Barros’ latest research studies scalar mixing: a process by which substances mix at the molecular level to produce a new compound.

Depending on their individual properties, particles that reach the subsurface can potentially dissolve into the water table — the level below the ground where water gathers due to the pull of gravity. By addressing the chemical contaminants that filter through the soil and travel underground, such as the pesticides used in agriculture, the study of scalar mixing could improve both health and ecological risk analysis.

De Barros, who earned a Ph.D. at the University of California, Berkeley, believes his work will provide reliable predictions of how pollutants travel in the subsurface and what the contamination risks for humans may be. This information will help decision-makers mitigate and better manage the corresponding risks.

“Creating models that realistically predict how pollutants travel in the subsurface will help us protect human health and allocate financial resources toward aquifer remediation,” de Barros said.

From theory to practice

Say that you spray your crop with agro-toxics to stop bugs from eating it. The chemicals contained in the spray will leach into the soil and reach subsurface water. Then they will begin to travel and eventually become part of the hydrologic cycle, better known as the water cycle.

“Studying how subsurface water flows gives us an idea of how long a contaminant will take to reach an environmentally sensitive target,” de Barros said. “If we could understand and characterize the behavior of subsurface water flows, this knowledge could help us keep our environment sustainable and predict contaminant pathways.

However, modeling this process sounds much simpler than it actually is. Unlike superficial water bodies, subsurface water doesn’t follow a defined course. It is completely mixed with the soil, which acts as a filter.

“We cannot see what is happening below the ground,” de Barros said. “Collecting information about the subsurface is extremely expensive, and predictions always include uncertainty bounds.”

No boundaries

The study of ground water involves different fields of engineering and science. If you think about a chemical spill as an extreme event that needs to be mitigated, it becomes a sustainability issue that integrates public health, geology, hydrology and hydrodynamics.

In the end, everything in science is related.

Felipe de Barros

“The way I see it, even if there are divisions in the broader field of engineering, there is always a connection between them,” de Barros said. “In the end, everything in science is related.”

Apart from the obvious link between engineering and other sciences, de Barros also sees a connection between engineering and art. In his opinion, developing a model requires a conceptual background, such as envisioning a painting or a sculpture.

“The existing perception of engineers is that we are all very methodic,” he said. “But in reality, there is a lot of creativity involved in our work.”

Like father, like son

De Barros’ father played a key role in developing his interest in engineering. A researcher himself, he dedicated his life to translating complex problems into predictable mathematical forms.

“I grew up watching my father solve very challenging problems,” de Barros said. “I remember looking at him and thinking ‘maybe I should do this,’ so I went to school for engineering.”

After earning his Ph.D., de Barros conducted ground water-related research in Brazil and Spain, in addition to actively collaborating with colleagues in Germany and Italy. He joined USC in 2013.

“The department and the people in it are simply fantastic,” he said. “USC Viterbi is inspiring in every possible way.”

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