ABSTRACT: PROJECT 4 Project 4 seeks to better understand the factors that result in solubilization of iAs and related oxyanion-forming trace elements (V, Cr) in well water. It is generally accepted that biogeochemical processes (rock weathering, redox transformations) control solubilization of these contaminants from aquifer materials. However, detailed mechanistic understanding of subsurface processes and an ability to apply biogeochemical parameters as predictors of contamination are lacking, and as a result, drinking-water wells may be susceptible to contamination. The central hypothesis is that the concentrations of specific rock- and groundwater- hosted chemical oxidants can be used to predict the risks of iAs, V, and Cr contamination in drinking- water wells, guide remediation strategies for co-contaminated sites, and facilitate health interventions. This topic is particularly relevant in North Carolina, which has 20 Superfund sites with documented As, as well as significant population utilizing drinking-water wells with elevated iAs, V, and Cr from geogenic sources. We thus propose a multipronged plan that integrates field, laboratory, and spectroscopic measurements with mechanistic and geospatial modeling to (1) develop a comprehensive multiscale understanding of the contrasting redox-driven mechanisms of iAs, V, and Cr solubilization, and (2) derive tools for predicting current and future contamination of well water. The use of fundamental research to develop geochemical predictors of contamination is aligned with the theme of the center “Identifying novel methods to reduce iAs exposure and elucidating mechanisms underlying iAs-induced metabolic dysfunction with a vision for disease prevention.” proposed research will facilitate disease prevention by guiding future well placement and monitoring efforts, potentially increasing awareness and decreasing exposure to naturally occurring toxic trace elements. Furthermore, this research will motivate novel interventions for responding to contaminants in the environment, including geogenically impacted sites in North Carolina, as well as in anthropogenically impacted locations such as Superfund sites.