Around the world, over 100 million people routinely consume well water with naturally occurring arsenic concentrations that exceed safe drinking-water guidelines. Although the global scale, health impacts, and extreme societal costs of arsenic contamination are apparent, it is less well understood to what extent arsenic may threaten groundwater that is currently arsenic-free. This issue is critical because arsenic contamination of previously uncontaminated aquifers has been observed to occur over timescales of decades. The overall goal of this research is to quantify the potential for future arsenic contamination of groundwater from sources that are both internal and external to aquifers. To achieve this goal, we will conduct a suite of field, laboratory and spectroscopic analyses on sediment samples from a well-characterized aquifer in Cambodia, where groundwater is potentially at risk for future arsenic contamination. In particular, this work will take advantage of natural sediment variability to investigate how the quantities and chemical reactivities of specific minerals govern arsenic concentrations in well water.
Results from this project will advance fundamental concepts in biogeochemistry by providing a new conceptual model for the coupled cycling of elements that impact arsenic distributions in the subsurface. Research outcomes will have direct implications for the sustainability and safety of water resources, and to maximize benefits of project results, informational briefs about risks for arsenic contamination will be widely disseminated to policy makers and people who consume well water. The project will galvanize a developing collaboration between two early-career scientists, and train a postodoctoral scholar, a Ph.D. student, and undergraduates in advanced approaches for assessing biogeochemical processes impacting contaminants in the environment. Project materials will be harnessed to develop programs for K-12 students that highlight local water quality issues, motivate understanding of basic science concepts, and provide hands-on exposure to aspects of environmental science outside the realms of typical classroom curricula.
