Page 31 - Engineering Penn State Magazine: Fall/Winter 2020

Research
ENVIRONMENT
Photo credti: Lauren E. McPhillips
Optimizing detention basins
by A’ndrea Elyse Messer
Stormwater detention basins intended to control the flow of rainwater and runoff might help in controlling nitrogen runoff into rivers and lakes, according to Lauren E. McPhillips, assistant professor of civil and environmental engineering at Penn State.
Speaking in August at the annual meeting of the Ecological Society of America in Louisville, Kentucky, she explained that she and colleagues at Cornell University looked at stormwater detention basins in the area around Ithaca, New York.
Controlling runoff from rain and trapping sediment has always been a goal
of these ubiquitous basins, but new techniques may make them suitable for removing nitrate from the water as well. The basins the researchers examined are in urban and suburban areas, and nitrate comes from atmospheric deposition on roads, car combustion, and lawn fertilizers.
“Typically, the basins are designed to be dry, but as sediment from runoff and vegetation that grows in the basins builds up, they can become wet basins,” McPhillips said.
They found that the capability of producing gaseous nitrogen was higher in wet basins than dry basins. However, they also found that partial conversion produced nitrous oxides and that consumption of organic matter produces methane, both greenhouse gases. The wet basins showed higher levels of the gene that allows complete conversion of nitrate to gaseous nitrogen.
According to McPhillips, designing the basins to hold water from the beginning could decrease production of nitrous oxides, because the longer the basins hold the water, the more complete the conversion from nitrate to gaseous nitrogen. n
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Expedition explores ocean carbon dioxide
by Erin Cassidy Hendrick
Matthew Rau, assistant professor of mechanical engineering at Penn State, spent 10 days cruising north of Oahu, Hawaii, in the summer of 2019. But it wasn’t for a vacation— Rau was conducting foundational research that could aid the understanding of carbon dioxide absorption within the Pacific Ocean and its potential impact on climate change.
“The ocean is full of particulate matter, like clay, sand, microplastics, but it’s mostly organic matter like plankton,” he said. “These particulates often end up clumping together and the bigger they get, the deeper they can settle in the water.”
This has some benefits, mainly that the carbon dioxide naturally absorbed into these particulates also sinks further into the ocean. An effect of this phenomena is carbon sequestration, which is the long-term storage of the gas that can help moderate climate change and ocean acidification.
“This is a small piece of a really
big puzzle,” Rau said. “Through this work, if we can make better predictions on how the ocean sequesters carbon, our predictions for carbon dioxide uptake from
the atmosphere and its role in our changing climate will be better.” n
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Matthew Rau (left), assistant professor of mechanical engineering, and his fellow scientists conduct field work north of Oahu, Hawaii.
FALL/WINTER 2020 31
DRY BASIN
WET BASIN