Evaluation of concentration of some heavy metals in ground water resources of Qahavand Plain-Hamedan

Given the increasing pollution and decreasing quality of water resources due to agricultural، industrial and urban development activities، this study was conducted to evaluate the concentration of As، Zn، Pb and Cu in groundwater resources of Qahavand Plain and to prepare the zoning map using GIS. Groundwater samples were collected from 20 selected wells during two spring and summer in 2012. The concentrations of elements in the samples were determined by ICP after laboratory preparations. All statistical analyses were performed using the SPSS statistical package. Also، spatial distribution map of elements was prepared by ArcGIS software using Kriging Method. The results showed that mean concentrations of As، Zn، Pb and Cu in groundwater samples in the spring were 7. 5±1. 2، 13. 7±2. 1، 2. 5±0. 4 and 9. 2±2 ppb، respectively، and mean concentrations of these elements in groundwater samples in the summer were 9±1. 2، 7. 1±1. 9، 2. 8±0. 65 and 9. 3±1. 2 ppb، respectively. Also، the results of one-sample t-test، comparing the mean concentrations of evaluated metals in groundwater samples with WHO and ISIRI showed a significant difference with permissible limit (P<0. 001)، so that the mean concentration of all metals was lower than the standard limit. The mean concentration of Zn was significantly lower in the summer than in the spring (P=0. 003). Although، the current groundwater resources of Qahavand Plain are not exceedingly polluted with heavy metals، long-term and excessive use of agricultural inputs and construction of polluting industries can threaten the groundwater resources of this area، followed by irreversible consequences such as health-related risks for consumers.