New Waves November 2008

Breaking news about water resources research and education in Texas

TWRI grant recipient studies groundwater input to the Brazos River

By Caitlin Churchill

Rice University graduate student Fanwei Zeng is earning her doctorate in biogeochemistry as she works with her advising professor Dr. Carrie Masiello to test using carbon isotopes as a tool to estimate groundwater input from carbonate-containing aquifers to rivers. For this project, she measured dissolved inorganic carbon in the Brazos River.

Zeng, a native of China and graduate from the University of Science and Technology of China, is a recipient of a 2007-08 Texas Water Resources Institute (TWRI) research grant. With the $5,000 research grant, Zeng said she found that carbonate input to rivers can be detected using carbon isotopes. However, she is not yet ready to apply these carbon isotopic techniques to estimate groundwater. More research on the input of carbonate from surface water and interflow runoff and atmospheric carbon dioxide is needed, she said.

According to Zeng's report, she chose the Brazos River as her field site because the natural variation in bedrock carbonate content created near-ideal conditions for initial tests. Studying the area of the lower Brazos from Waco to the river mouth, Zeng concluded that the Brazos is supersaturated with carbon dioxide at all times of the year with different parts of the river having varying sources of carbon.

Zeng hopes her research can help people better understand regional carbon budgets. "Parts of Texas, Louisiana, Mississippi, Alabama, Georgia, South Carolina and all of Florida are in the same ecological region," she said. "It is likely that rivers in these areas behave similarly to the rivers we are studying."

She said results obtained from her study about groundwater discharge to subtropical rivers can be combined with results from other ecosystem types to ultimately model the global carbon cycle.

As Zeng completes her doctorate, she plans to continue working on carbon cycling related research.

Her research was funded by TWRI with funds obtained through the U.S. Geological Survey as part of the National Institutes for Water Research annual research program. TWRI is the designated institute for water resources research in Texas.

For more information on Zeng's research, visit USGS Research Grants.

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