Document Type : Original Article
Master of Rangeland and Watershed Management University of Gonbad Kavous
Rangeland and Watershed Professors Gonbadkavus University
faculty member / Gonbad Kavous University
Professor of Geology Department of Golestan University
Rangeland and Watershed Professors of Gonbadkavos University
This study was conducted to evaluate the quality of groundwater resources in Gorgan using heavy metal indices. For this purpose, the chemical analysis results of 63 drinking water wells were used in the two seasons of spring and autumn. Concentration of four heavy metals (arsenic, lead, iron, and manganese) in groundwater was measured by ICP in the Golestan Provincial Water and Wastewater Department laboratory. To evaluate the groundwater contamination by heavy metals, Heavy Metal Pollution Index (HPI), Degree of Contamination (Cd), and Heavy Metal Evaluation Index (HEI), were used. Results revealed that the concentration of heavy metals did not change much in spring and autumn. Also, the results of paired t-test showed that there is no significant difference between heavy metal concentrations in spring and autumn. Heavy metal distribution map shows that average value of heavy metals in the western part of the aquifer is increasing from south to north. The highest concentration of these metals in residential areas with high population density and the old texture of the city increased dramatically. Results revealed that the average values of HPI, Cd, and HEI index in the spring and fall of are less than the critical amount of contamination for drinking water. Although, Gorgan groundwater is currently not contaminated in terms of metal indices, but essential operations should be taken for the proper disposal of municipal wastewater and industrial and agricultural effluents. It is also recommended to monitor the groundwater resources of study area periodically in terms of heavy metal concentrations.