ARSENIC SOURCE TERMS FOR REACTIVE TRANSPORT MODELS

Release of arsenic (As) from naturally-occurring minerals is the primary source of As-contaminated groundwater worldwide. However, there is not a simple correlation between the As content of the aquifer solids and the As concentration in the coexisting groundwater. Quantifying the rate of transfer of As from aquifer materials into groundwater is a key step toward creating models suitable for managing As-contaminated groundwater. We have developed a methodology to derive As source terms for common As-bearing minerals, including arsenopyrite, realgar, scorodite, and pyrite, for use in reactive transport models. In addition, we apply a shrinking particle model to examine how the rates of As release decline over time. This methodology for constructing reactive transport models for As in groundwater can be modified to derive source terms for other trace elements of environmental interest.