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What’s in your water?

For a scholar whose research focuses on aquatic environmental chemistry, Philip Larese-Casanova spends little time doing research in the environment. “I don’t take water samples and I don’t go to drinking water plants or wastewater treatment plants,” said the assistant professor of civil and environmental engineering.

That’s because most of the pollutants Larese-Casanova is interested in haven’t been around long enough to make that kind of work feasible. Or, if the materials themselves aren’t brand new, the processes he’s investigating are.

“If we know how a material is going to behave, then we can design cleanup strategies,” he said. Understanding the behavior has to come first. That is, how will this new material—when dispersed in water and exposed to sunlight, for example—react with the nearby minerals and organic material. Will it dissolve in the water and be ingested by fish, or will it leach out into the soil?

Backed by funding from a recently awarded National Science Foundation CAREER grant, Larese-Casanova is expanding his research in metallic water pollutants to include quantum dots—mixed-metal materials that are used in energy production and electronics and are smaller than even the smallest nanomaterials. As researchers learn more about quantum dots, they are primed to become a ubiquitous material in modern technologies. Understanding their impact on the environment is therefore critical, Larese-Casanova said.

“We have a good idea of how metallic nanoparticles behave in water because there’s a large body of research,” Larese-Casanova explained, “but now quantum dots are at even a smaller size.” By virtue of their size, the same metals can display drastically different properties in the environment.

The NSF grant has enabled Larese-Casanova’s team to acquire a device that blasts molecules apart into their component elements. “The goal is to use this instrument for simultaneous measurement of dissolved and particulate metals,” he said. The method will allow the team to investigate the aquatic behavior of quantum dots at a variety of levels, meaningful once they reach our actual rivers and streams.

Quantum dots are already being researched in laboratories around the globe and may soon power our cell phones. Larese-Casanova wants to know what impact these tiny particles will have on the aquatic systems in which they end up. But that question cannot be answered without first understanding the very basic level of quantum dot behavior in water.

“I want to protect our water resources,” he said. “There are so many aspects to the discussion from drinking water to waste waters. I’d like to do my part.” While his part takes place in a series of beakers and vials on the laboratory bench top, it is clear that his work lays the necessary foundation for other researchers to build upon.