Reactive Transport Modeling of Arsenic Mobilization in Groundwater of the Red River Floodplain, Vietnam☆

The arsenic content in groundwater of the Red River floodplain decreases with the burial age of the aquifer sediment over a 6000 year period. This decrease is caused by diminishing reactivities of both sedimentary organic carbon, Fe-oxides as well as CaCO3. Here we present a 1-D reactive transport model developed in PHREEQC-3 that quantifies the resulting changes in groundwater bulk chemistry as well as arsenic content over the last six millennia.