en تخصصي Special مقاله اصیل Original Article <p dir="ltr" style="text-align: justify;"><strong>Background: </strong>Iran is located within the dry and semi dry regions, thus almost 90% of the required water is secured via the use of groundwater. Owing to the increasing pollution of water resources, this study was performed to evaluate water quality pollution indices for heavy metals (As, Zn, Pb and Cu) contamination monitoring in Toyserkan Plain during spring and summer in 2012.</p> <p dir="ltr" style="text-align: justify;"><strong>Methods: </strong>A total of 20 ground water wells were chosen randomly. The samples were filtered (0.45 &mu;m) and kept cool in polyethylene bottles. Samples were taken for the analysis of metals, the former was acidified with HNO3 to pH lower than 2. Metal concentrations were determined using ICP-OES.</p> <p dir="ltr" style="text-align: justify;"><strong>Results: </strong>The results revealed that the mean values of contamination index (Cd), heavy metal pollution index (HPI) and heavy metal evaluation index (HEI) in samples for spring season were -2.81, 9.74 and 1.20, respectively and were -2.67, 9.51 and 1.32, respectively in samples for summer season and this indicates low contamination levels. Comparing the mean concentrations of the evaluated metals with WHO permissible limits demonstrated a significant difference (<em>P </em>< 0.05). Thus, the mean concentrations of the metals were significantly lower than the permissible limits.</p> <p dir="ltr" style="text-align: justify;"><strong>Conclusion: </strong>Although the heavy metal pollution of the ground water in Toyserkan Plain is not higher than permissible limits, the irregular and long-term utilization of agricultural inputs, use of wastewater and sewage sludge in agriculture, over utilization of organic fertilizers and establishment of pollutant industries can threaten the ground water, and cause irreversible damages in this area.</p> Heavy metals, Groundwater, Water quality pollution indices, Toyserkan Plain 21 27 http://ehemj.com/browse.php?a_code=A-10-1-72&slc_lang=en&sid=1 Soheil Sobhanardakani s_sobhan@iauh.ac.ir 10031947532846002806 10031947532846002806 Yes Department of the Environment, College of Basic Sciences, Hamedan Branch, Islamic Azad University, Hamedan, Iran Lobat Taghavi 10031947532846002807 10031947532846002807 No Department of the Environmental Pollution, College of Environment and Energy, Science and Research Branch, Islamic Azad University, Tehran, Iran Behzad Shahmoradi 10031947532846002808 10031947532846002808 No Kurdistan Environmental Health Research Center, Kurdistan University of Medical Sciences, Sanandaj, Iran Amin Jahangard 10031947532846002809 10031947532846002809 No Young Researchers & Elite Club, Hamedan Branch, Islamic Azad University, Hamedan, Iran