The Source of Natural Arsenic Contamination in Groundwater, West of Iran

Geochemical characteristics and arsenic content of groundwater in the Kurdistan and West Azerbaijan provinces (west of Iran) were analyzed. Groundwater is the local source of drinking water and travertine springs are mainly used for bathing and balneological purposes. The results indicate that total arsenic in travertine springs and groundwater range between 212 to 986.9 and 0.4 to 688.9 mu g/L, respectively. Speciation of arsenic suggests arsenite the dominant arsenic species in travertine spring (68.2 to 98.9%). The variations of Br/Cl and B/Cl ratio, negative ORP (Oxygen Redox Potential) and high concentrations of Cl, Na, Cs, Li, Rb, Sr, B, Br and Rb in travertine spring samples confirm deep groundwater circulation in the volcanic basement. The results of saturation indices show that groundwater samples are supersaturated with respect to iron oxides, calcite, dolomite and aragonite and undersaturated with respect to gypsum and halite. In spite of gold mineralization, dissolution of arsenic-containing sulfide minerals is not the main source of arsenic contamination in groundwater. Spatial coincidence between the arsenic anomaly in groundwater and the travertine springs distribution illustrates they are the main source of arsenic in groundwater. The present study is useful in addressing future measures in groundwater resource management, in the volcanic regions in the west of Iran.