Dynamic behaviors of water levels and arsenic concentration in shallow groundwater from the Hetao Basin, Inner Mongolia

► Groundwater level temporally fluctuated during 4 years. ► Slight increasing trends in As concentration were observed over 4 years. ► Iron concentrations generally kept relatively constant. ► Increasing As concentrations would be associated with increasing water levels. ► Decoupling of temporal variation in As with Fe should be reductive desorption of As.