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Athena Nghiem, Columbia University and Lamont-Doherty Earth Observatory (New York, US)

Abstract

Naturally occurring contamination of groundwater by arsenic threatens the health of millions who rely on groundwater for drinking water. Arsenic is typically sorbed onto the surface of iron (Fe) minerals and is believed to be released by microbial dissolution under reducing conditions, coupled to the oxidation of organic carbon. However, arsenic release is affected by many other factors, including recharge source into the groundwater aquifer and Fe mineralogy within the aquifer. Here, these two factors will be presented where data-driven, statistical approaches have provided further insight into how they affect arsenic release. In the first case, a novel end‐member mixing model is used to determine fraction recharge from various sources to an aquifer. Here, we find that groundwater arsenic and dissolved organic carbon concentrations are controlled by the dominant source of recharge. In the second case, machine learning is performed on Fe mineralogy data to delineate past change where an uncontaminated aquifer has become contaminated. We also show that another extent of the uncontaminated aquifer may be susceptible to future arsenic release. These data-driven approaches both contribute to an understanding of arsenic release that threatens water resources worldwide and demonstrate how to derive more information from our data as current research continues to produce more data.

Bio

Athena Nghiem is a PhD candidate in geochemistry at Columbia University and Lamont-Doherty Earth Observatory (New York, US). Her research focuses on groundwater arsenic contamination and investigating biogeochemical mechanisms for arsenic release. She is a trainee in the Columbia University Superfund Research Program and is also involved in a worldwide collaborative effort through the United States Geological Survey Powell Center to compile and explore the large volume of published groundwater arsenic datasets. She holds an M.Phil. & MA from Columbia University in geochemistry and a BA from the University of California, Berkeley in geophysics and statistics.

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