This study was carried out to assess the groundwater pollution in the northern Develi Closed Basin by using the heavy metal pollution index (HPI). Samples from 10 wells and 5 springs were collected in dry and wet seasons and concentrations of Pb, Zn, Cr, Mn, Fe, Cu, Cd, As and B were determined. In both seasons, for more than half of the samples, As, B and Fe concentrations exceeded the Turkish drinking water guideline values. Due to the occurrence of these metals in high concentrations in some samples HPI values are up to 1740. The source of these metals is geogenic and attributed to the interaction of these waters with highly altered volcanic and pyroclastic rocks. The overall HPI for wet and dry periods are reported as 360 and 440, respectively. Accordingly, the pollution level in the groundwater of this area is unacceptable.
Keywords: Geogenic water pollution; Groundwater; Heavy metal pollution index; Kayseri; Turkey.