Occurrence, distribution, and release mechanism of arsenic in aquifers of Yinchuan Plain in China

Major and trace elements in the forty-four core sediment samples from Yinchuan Plain were analyzed by polarized energy dispersive X-Ray Fluorescence (XRF) and inductively coupled plasma mass spectrometry (ICP-MS). Arsenic concentration in groundwater was determined using Hydride Generation-Atomic Fluorescence Spectrometry (HG-AFS). Arsenic concentration in core sediments of Yinchuan Plain is well correlated with Cu (R = 0.582), total iron oxide (R = 0.483), Mn (R = 0.564), Ba (R = 0.548), Zn (R = 0.542), F (R = 0.512), N (R = 0.491) and organic carbon (R = 0.592). Arsenic contents in the sediments range from 3.7 to 49.8 mg/kg, with an average of 9.2 mg/kg. High As is released from sediment samples during reduction of the iron oxides/oxyhydroxides. For groundwater table increases in shallow aquifer and Oxidation-Reduction Potential (ORP) value decreases in irrigation period, arsenic can be much easier to release into groundwater of Yinchuan Plain.