Geochemistry of High Arsenic Groundwaters in the Yinchuan Basin, P.R. China

High As groundwaters have been usually found in inland basins of north-west China. However, few data are available on groundwater As in the Yinchuan basin. Ninety-eight groundwater samples were taken from the alluvial fans, basin center, and fluvial plain of the Yellow River in the basin. Results showed that low As groundwater occurred in the alluvial fans and the basin center, while high As groundwater was present near the Yellow River. The redox potential was the key factor controlling the groundwater As concentrations. Arsenic was mobilized in reducing conditions via reductive dissolution of Fe oxides, which was supported by the positive correlation between As and Fe. In comparison to the Hetao basin, the Yinchuan groundwater had lower As concentration, lower pH, and higher redox potential.