Factors controlling mobility of I and I species in an acidic groundwater plume at the Savannah River Site

Otosaka, Shigeyoshi  ; Schwehr, K. A.*; Kaplan, D. I.*; Roberts, K. A.*; Zhang, S.*; Xu, C.*; Li, H.-P.*; Ho, Y.-F.*; Brinkmeyer, R.*; Yeager, C. M.*; Santschi, P. H.*

Spatial distributions of concentrations and speciation of radioiodine (I) and stable iodine (I) in groundwater in the vicinity of the F-area seepage basin at the U.S. Department Energy of Savannah River Site were investigated. I concentration in groundwater was 8.6 Bq/L immediately downstream of the seepage basin (well FSB-95DR), and decreased with distance from the infiltration basin. I concentration decreased similarly to that of I. Although there was no potential I source in wastes in the basin, I also showed a similar gradient to that of I. High concentrations of I or I were not detected in groundwater collected from wells located outside of the mixed waste plume of this area. The high iodide concentrations in groundwater near the basin were presumed to be caused by dissolution of iodide from soil due to gradually increasing of pH values in the last decade.